TARGETED ANTIMICROBIAL MOIETIES
This invention provides novel targeted antimicrobial compositions. In various embodiments chimeric moieties are provided comprising an antimicrobial peptide attached to a peptide targeting moiety that binds a bacterial strain or species.
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This application is a divisional of U.S. patent application Ser. No. 12/701,443, filed on Feb. 5, 2010, which claims priority to U.S. Provisional Application No. 61/150,287, filed Feb. 5, 2009; and to U.S. Provisional Application No. 61/224,825, filed Jul. 10, 2009, the disclosures of which are incorporated herein by reference in their entirety for all purposes.
STATEMENT OF GOVERNMENTAL SUPPORT[Not Applicable]
FIELD OF THE INVENTIONThe present invention relates to novel targeting peptides, novel antimicrobial peptides, chimeric moieties comprising novel targeting and/or novel antimicrobial peptides and uses thereof.
BACKGROUND OF THE INVENTIONAntibiotic research at the industrial level was originally focused on the identification of refined variants of already existing drugs. This resulted example, in the development of antibiotics such as newer penicillins, cephalosporins, macrolides, and fluoroquinolones.
However, resistance to old and newer antibiotics among bacterial pathogens is evolving rapidly, as exemplified by extended beta-lactamase (ESBL) and quinolone resistant gram-negatives, multi-resistant gonococci, methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant enterococci (VRE), penicillin non-susceptible pneumococci (PNSP) and macrolide resistant pneumococci and streptococci (see, e.g., Panlilo et al. (1992) Infect. Control Hosp. EpidemioL., 13: 582-586; Morris et al. (1995) Ann Intern Med., 123: 250-259, and the like). An overuse, or improper use, of antibiotics is believed to be of great importance for triggering and spread of drug resistant bacteria. Microbes have, in many cases, adapted and are resistant to antibiotics due to constant exposure and improper use of the drugs.
Drug resistant pathogens represent a major economic burden for health-care systems. For example, postoperative and other nosocomial infections will prolong the need for hospital care and increase antibiotic drug expenses. It is estimated that the annual cost of treating drug resistant infections in the United States is approximately $5 billion.
SUMMARY OF THE INVENTIONIn certain embodiments, novel targeting moieties (e.g., peptides) that specifically/preferentially bind to microorganisms (e.g., certain bacteria, yeasts, fungi, molds, viruses, algae, protozoa, and the like) are provided. The targeting moieties can be attached to effectors (e.g., detectable labels, drugs, antimicrobial peptides, etc.) to form chimeric constructs for specifically/preferentially delivering the effector to and/or into the target organism. In certain embodiments novel antimicrobial peptides that can be used to inhibit (e.g., kill and/or inhibit growth and/or proliferation) of certain microorganisms (e.g., certain bacteria, yeasts, fungi, molds, viruses, algae, protozoa, and the like) are provided. Any targeting moiety disclosed herein can be attached to any one or more effector disclosed herein. Any targeting moiety disclosed herein can be attached to any one or more antimicrobial peptide disclosed herein.
In certain embodiments chimeric moieties are provided where the chimeric moieties comprise an effector attached to a peptide targeting moiety comprising or consisting of the amino acid sequence of a peptide found in Table 2 and/or Table 15. In certain embodiments the targeting peptide comprises or consists of amino acid or retro or inverso or retro-inverso sequence or beta sequence of a peptide found in Table 2 and/or Table 15. In certain embodiments the effector comprises a moiety selected from the group consisting of a detectable label, an antimicrobial peptide, an antibiotic, and a photosensitizer. In certain embodiments the effector comprises an antimicrobial peptide comprising the amino acid sequence of a peptide found in Table 2, and/or Table 8, and/or Table 9, and/or Table 10. In certain embodiments the effector comprises an antibiotic found in Table 7. In certain embodiments the effector comprises a photosensitizer. In certain embodiments the photosensitizer is selected from the group consisting of a porphyrinic macrocycle, a porphyrin, a chlorine, a crown ether, an acridine, an azine, a phthalocyanine, a cyanine, a psoralen, and a perylenequinonoid. In certain embodiments the photosensitizing agent is an agent shown in any of
Also provided is a chimeric construct comprising a targeting moiety attached to an antimicrobial peptide where the antimicrobial peptide comprises or consists of the amino acid or retro or inverso or retro-inverso sequence of a peptide found in Table 2. In certain embodiments the targeting moiety is a peptide that comprises or consists of the amino acid or retro or inverso or retro-inverso or beta sequence of a peptide found in Table 2, and/or Table 3, and/or Table 4, and/or Table 6, and/or Table 15. In certain embodiments, the targeting moiety comprises an antibody (e.g., an antibody identified in Table 5). In certain embodiments the targeting moiety is chemically conjugated to the effector directly or via a linker. In certain embodiments the targeting moiety is chemically conjugated to the effector via a linker comprising a polyethylene glycol (PEG). In certain embodiments the targeting moiety is chemically conjugated to the effector via a non-peptide linker found in Table 11. In certain embodiments the where the targeting moiety is linked to the effector via a peptide linkage. In certain embodiments the chimeric construct is a fusion protein. In certain embodiments the linker is a peptide linker found in Table 11. In certain embodiments the chimeric moiety is functionalized with a polymer (e.g., polyethylene glycol, a cellulose, a modified cellulose, etc.) to increase serum halflife.
Also provided are pharmaceutical compositions comprising the chimeric construct(s)/chimeric moieties described herein in a pharmaceutically acceptable carrier. In certain embodiments the composition is formulated as a unit dosage formulation. In certain embodiments the composition is formulated for administration by a modality selected from the group consisting of intraperitoneal administration, topical administration, oral administration, inhalation administration, transdermal administration, subdermal depot administration, and rectal administration.
Also provided is an antimicrobial composition comprising an isolated antimicrobial moiety comprising or consisting of the amino acid sequence of a peptide found in Table 2. In certain embodiments the peptide comprises or consists of the amino acid or retro or inverso or retro-inverso sequence or beta sequence of a peptide found in Table 2. In certain embodiments the peptide is a peptide selected from the group consisting of a peptide consisting of the amino acid sequence of a peptide found in Table 2 comprising all L residues, a peptide consisting of the amino acid sequence of a peptide found in Table 2 comprising a peptide found in Table comprising all D residues, a peptide comprising the inverse of an amino acid sequence found in Table 2, a peptide comprising the retro-inverso form of a peptide found in Table 2, a peptide found in Table 2 comprising a conservative substitution, and a peptide found in Table 2 comprising a substitution of a naturally occurring amino acid with a non-naturally occurring amino acid. In certain embodiments the peptide comprises no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 conservative substitutions.
Also provided is a composition comprising an isolated targeting moiety comprising or consisting of the amino acid sequence of a peptide found in Table 2 or Table 15. In certain embodiments the peptide comprises or consists of the amino acid or retro or inverso or retro-inverso sequence or beta sequence of a peptide found in Table 2 or Table 15. In certain embodiments the peptide is a peptide selected from the group consisting of a peptide consisting of the amino acid sequence of a peptide found in Table 2 or Table 15 comprising all L residues, a peptide consisting of the amino acid sequence of a peptide found in Table 2 comprising a peptide found in Table comprising all D residues, a peptide comprising the inverse of an amino acid sequence found in Table 2 or Table 15, a peptide comprising the retro-inverso form of a peptide found in Table 2 or Table 15, a peptide found in Table 2 or Table 15 comprising a conservative substitution, and a peptide found in Table 2 or Table 15 comprising a substitution of a naturally occurring amino acid with a non-naturally occurring amino acid. In certain embodiments the peptide comprises no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 conservative substitutions.
In certain embodiments methods are provided for inhibiting the growth and/or proliferation of a microorganism and/or a biofilm comprising a microorganism. The methods typically involve contacting the microorganism or biofilm with a composition comprising an antimicrobial peptide comprising or consisting of the amino acid sequence of a peptide found in Table 2 (e.g., the amino acid or retro or inverso or retro-inverso sequence or beta sequence of a peptide found in Table 2); and/or contacting the microorganism or biofilm with a composition comprising an antimicrobial moiety attached to a targeting peptide comprising or consisting of the amino acid sequence of a peptide found in Table 2 (e.g., the amino acid or retro or inverso or retro-inverso sequence or beta sequence of a peptide found in Table 2). In certain embodiments the microorganism or biofilm is a bacterium or a bacterial film. In certain embodiments the targeting peptide is chemically conjugated to the antimicrobial peptide. In certain embodiments the targeting peptide is linked directly to the antimicrobial peptide. In certain embodiments the targeting peptide is linked to the antimicrobial peptide via a linker comprising a polyethylene glycol. In certain embodiments the targeting peptide is linked to the antimicrobial peptide via a non-peptide linkage in Table 11. In certain embodiments the targeting peptide is linked to the antimicrobial peptide via a peptide linkage. In certain embodiments the targeting peptide linked to the antimicrobial peptide is a fusion protein. In certain embodiments the linker is a peptide linker in Table 11.
In various embodiments methods are provided for detecting a microorganism (e.g., bacteria, yeast, protozoan, virus, algae, fungi, etc.) or biofilm comprising the microorganism. The methods typically involve contacting the microorganism or biofilm with a composition comprising a detectable label attached to a targeting peptide comprising the amino acid sequence of a peptide comprising or consisting of the amino acid or retro or inverso or retro-inverso sequence of a peptide found in Table 2; and detecting the detectable label where the quantity and/or location of the detectable label is an indicator of the presence of the microorganism and/or biofilm film. In certain embodiments the microorganism or biofilm is a bacterium or a bacterial film. In certain embodiments the detectable label is a label selected from the group consisting of a radioactive label, a radio-opaque label, a fluorescent dye, a fluorescent protein, an enzymatic label, a colorimetric label, and a quantum dot.
In certain embodiments compositions are also provided comprising a photosensitizing agent attached to a targeting peptide where the targeting peptide comprising or consisting of the amino acid or retro or inverso or retro-inverso sequence of a peptide found in Table 2 or Table 15. In certain embodiments the photosensitizing agent is an agent selected from the group consisting of a porphyrinic macrocycle, a porphyrin, a chlorine, a crown ether, an acridine, an azine, a phthalocyanine, a cyanine, a psoralen, and a perylenequinonoid. In certain embodiments the photosensitizing agent is an agent shown in any of
In certain embodiments methods are provided for inhibiting the growth or proliferation of a microorganism and/or a biofilm (e.g., a bacterium and/or a bacterial film), where the methods involve contacting the a microorganism and/or a biofilm with a composition comprising a photosensitizing agent attached to a targeting peptide as described herein. In certain embodiments the method further comprises exposing the microorganism or biofilm to a light source. In certain embodiments the microorganism is a microorganism selected from the group consisting of a bacterium, a yeast, a fungus, a protozoan, and a virus. In certain embodiments the biofilm comprises a bacterial film.
In certain embodiments chimeric moieties are provided wherein the chimeric moiety comprises multiple targeting moieties attached to each other. In certain embodiments the targeting moieties are directly attached to each other. In certain embodiments the targeting moieties are attached to each other via a peptide linker. In certain embodiments the targeting moieties are attached to each other via a non-peptide linker. In certain embodiments chimeric moieties are provided wherein the chimeric moiety comprises multiple effectors attached to each other. In certain embodiments the effectors are directly attached to each other. In certain embodiments the effectors are attached to each other via a peptide linker. In certain embodiments the effectors are attached to each other via a non-peptide linker.
In certain embodiments chimeric moieties are provided where the chimeric moiety comprises one or more targeting moieties attached to one or more effectors. In certain embodiments the chimeric moiety comprises one or more of the targeting moieties shown in Table 2, and/or Table 4 and/or Table 6, and/or Table 15 attached to a single effector. In certain embodiments the chimeric moiety comprises one or more effectors attached to a single targeting moiety. In certain embodiments the chimeric moiety comprises one or more effectors comprising one or more of the antimicrobial peptides shown in Table 2, and/or Table 8, and/or Table 9, and/or Table 10 attached to a single targeting moiety. In certain embodiments the chimeric moiety comprises multiple targeting moieties attached to multiple effectors.
DEFINITIONSThe term “peptide” as used herein refers to a polymer of amino acid residues typically ranging in length from 2 to about 50 residues. In certain embodiments the peptide ranges in length from about 2, 3, 4, 5, 7, 9, 10, or 11 residues to about 50, 45, 40, 45, 30, 25, 20, or 15 residues. In certain embodiments the peptide ranges in length from about 8, 9, 10, 11, or 12 residues to about 15, 20 or 25 residues. Where an amino acid sequence is provided herein, L-, D-, or beta amino acid versions of the sequence are also contemplated as well as retro, inversion, and retro-inversion isoforms. Peptides also include amino acid polymers in which one or more amino acid residues is an artificial chemical analogue of a corresponding naturally occurring amino acid, as well as to naturally occurring amino acid polymers. In addition, the term applies to amino acids joined by a peptide linkage or by other, “modified linkages” (e.g., where the peptide bond is replaced by an α-ester, a β-ester, a thioamide, phosphonamide, carbomate, hydroxylate, and the like (see, e.g., Spatola, (1983) Chem. Biochem. Amino Acids and Proteins 7: 267-357), where the amide is replaced with a saturated amine (see, e.g., Skiles et al., U.S. Pat. No. 4,496,542, which is incorporated herein by reference, and Kaltenbronn et al., (1990) Pp. 969-970 in Proc. 11th American Peptide Symposium, ESCOM Science Publishers, The Netherlands, and the like)).
The term “residue”” as used herein refers to natural, synthetic, or modified amino acids. Various amino acid analogues include, but are not limited to 2-aminoadipic acid, 3-aminoadipic acid, beta-alanine (beta-aminopropionic acid), 2-aminobutyric acid, 4-aminobutyric acid, piperidinic acid, 6-aminocaproic acid, 2-aminoheptanoic acid, 2-aminoisobutyric acid, 3-aminoisobutyric acid, 2-aminopimelic acid, 2,4 diaminobutyric acid, desmosine, 2,2′-diaminopimelic acid, 2,3-diaminopropionic acid, n-ethylglycine, n-ethylasparagine, hydroxylysine, allo-hydroxylysine, 3-hydroxyproline, 4-hydroxyproline, isodesmosine, allo-isoleucine, n-methylglycine, sarcosine, n-methylisoleucine, 6-n-methyllysine, n-methylvaline, norvaline, norleucine, ornithine, and the like. These modified amino acids are illustrative and not intended to be limiting.
“β-peptides” comprise of “β amino acids”, which have their amino group bonded to the β carbon rather than the α-carbon as in the 20 standard biological amino acids. The only commonly naturally occurring β amino acid is β-alanine.
Peptoids, or N-substituted glycines, are a specific subclass of peptidomimetics. They are closely related to their natural peptide counterparts, but differ chemically in that their side chains are appended to nitrogen atoms along the molecule's backbone, rather than to the α-carbons (as they are in natural amino acids).
The terms “conventional” and “natural” as applied to peptides herein refer to peptides, constructed only from the naturally-occurring amino acids: Ala, Cys, Asp, Glu, Glu, Phe, Gly, His, Ile, Lys, Leu, Met, Asn, Pro, Gln, Arg, Ser, Thr, Val, Trp, and Tyr. A compound of the invention “corresponds” to a natural peptide if it elicits a biological activity (e.g., antimicrobial activity) related to the biological activity and/or specificity of the naturally occurring peptide. The elicited activity may be the same as, greater than or less than that of the natural peptide. In general, such a peptoid will have an essentially corresponding monomer sequence, where a natural amino acid is replaced by an N-substituted glycine derivative, if the N-substituted glycine derivative resembles the original amino acid in hydrophilicity, hydrophobicity, polarity, etc. Thus, for example, the following pairs of peptides would be considered “corresponding”:
In these examples, “Val*” refers to N-(prop-2-yl)glycine, “Phe*” refers to N-benzylglycine, “Ser*” refers to N-(2-hydroxyethyl)glycine, “Leu*” refers to N-(2-methylprop-1-yl)glycine, and “Ile*” refers to N-(1-methylprop-1-yl)glycine. The correspondence need not be exact: for example, N-(2-hydroxyethyl)glycine may substitute for Ser, Thr, Cys, and Met. N-(2-methylprop-1-yl)glycine may substitute for Val, Leu, and Ile. Note in IIIa and IIIb above that Ser* is used to substitute for Thr and Ser, despite the structural differences: the sidechain in Ser* is one methylene group longer than that of Ser, and differs from Thr in the site of hydroxy-substitution. In general, one may use an N-hydroxyalkyl-substituted glycine to substitute for any polar amino acid, an N-benzyl- or N-aralkyl-substituted glycine to replace any aromatic amino acid (e.g., Phe, Trp, etc.), an N-alkyl-substituted glycine such as N-butylglycine to replace any nonpolar amino acid (e.g., Leu, Val, Ile, etc.), and an N-(aminoalkyl)glycine derivative to replace any basic polar amino acid (e.g., Lys and Arg).
A “compound antimicrobial peptide” or “compound AMP” refers to a construct comprising two or more AMPs joined together. The AMPs can be joined directly or through a linker. They can be chemically conjugated or, where joined directly together or through a peptide linker can comprise a fusion protein.
In certain embodiments, conservative substitutions of the amino acids comprising any of the sequences described herein are contemplated. In various embodiments one, two, three, four, or five different residues are substituted. The term “conservative substitution” is used to reflect amino acid substitutions that do not substantially alter the activity (e.g., antimicrobial activity and/or specificity) of the molecule. Typically conservative amino acid substitutions involve substitution one amino acid for another amino acid with similar chemical properties (e.g. charge or hydrophobicity). Certain conservative substitutions include “analog substitutions” where a standard amino acid is replaced by a non-standard (e.g., rare, synthetic, etc) amino acid differing minimally from the parental residue. Amino acid analogs are considered to be derived synthetically from the standard amino acids without sufficient change to the structure of the parent, are isomers, or are metabolite precursors. Examples of such “analog substitutions” include, but are not limited to, 1) Lys-Orn, 2) Leu-Norleucine, 3) Lys-Lys[TFA], 4) Phe-Phe[Gly], and 5) δ-amino butylglycine-ξ-amino hexylglycine, where Phe[gly] refers to phenylglycine (a Phe derivative with a H rather than CH3 component in the R group), and Lys[TFA] refers to a Lys where a negatively charged ion (e.g., TFA) is attached to the amine R group. Other conservative substitutions include “functional substitutions” where the general chemistries of the two residues are similar, and can be sufficient to mimic or partially recover the function of the native peptide. Strong functional substitutions include, but are not limited to 1) Gly/Ala, 2) Arg/Lys, 3) Ser/Tyr/Thr, 4) Leu/Ile/Val, 5) Asp/Glu, 6) Gln/Asn, and 7) Phe/Trp/Tyr, while other functional substitutions include, but are not limited to 8) Gly/Ala/Pro, 9) Tyr/His, 10) Arg/Lys/His, 11) Ser/Thr/Cys, 12) Leu/Ile/Val/Met, and 13) Met/Lys (special case under hydrophobic conditions). Various “broad conservative substations” include substitutions where amino acids replace other amino acids from the same biochemical or biophysical grouping. This is similarity at a basic level and stems from efforts to classify the original 20 natural amino acids. Such substitutions include 1) nonpolar side chains: Gly/Ala/Val/Leu/Ile/Met/Pro/Phe/Trp, and/or 2) uncharged polar side chains Ser/Thr/Asn/Gln/Tyr/Cys. In certain embodiments broad-level substitutions can also occur as paired substitutions. For example, any hydrophilic neutral pair [Ser, Thr, Gln, Asn, Tyr, Cys]+[Ser, Thr, Gln, Asn, Tyr, Cys] can may be replaced by a charge-neutral charged pair [Arg, Lys, His]+[Asp, Glu]. The following six groups each contain amino acids that are typical conservative substitutions for one another: 1) Alanine (A), Serine (S), Threonine (T); 2) Aspartic acid (D), Glutamic acid (E); 3) Asparagine (N), Glutamine (Q); 4) Arginine (R), Lysine (K), Histidine (H); 5) Isoleucine (I), Leucine (L), Methionine (M), Valine (V); and 6) Phenylalanine (F), Tyrosine (Y), Tryptophan (W).
In certain embodiments, targeting peptides, antimicrobial peptides, and/or STAMPs compromising at least 80%, preferably at least 85% or 90%, and more preferably at least 95% or 98% sequence identity with any of the sequences described herein are also contemplated. The terms “identical” or percent “identity,” refer to two or more sequences that are the same or have a specified percentage of amino acid residues that are the same, when compared and aligned for maximum correspondence, as measured using one of the following sequence comparison algorithms or by visual inspection. With respect to the peptides of this invention sequence identity is determined over the full length of the peptide. For sequence comparison, typically one sequence acts as a reference sequence, to which test sequences are compared. When using a sequence comparison algorithm, test and reference sequences are input into a computer, subsequence coordinates are designated, if necessary, and sequence algorithm program parameters are designated. The sequence comparison algorithm then calculates the percent sequence identity for the test sequence(s) relative to the reference sequence, based on the designated program parameters. Optimal alignment of sequences for comparison can be conducted, e.g., by the local homology algorithm of Smith & Waterman (1981) Adv. Appl. Math. 2: 482, by the homology alignment algorithm of Needleman & Wunsch (1970) J. Mol. Biol. 48: 443, by the search for similarity method of Pearson & Lipman (1988) Proc. Natl. Acad. Sci., USA, 85: 2444, by computerized implementations of these algorithms (GAP, BESTFIT, FASTA, and TFASTA in the Wisconsin Genetics Software Package, Genetics Computer Group, 575 Science Dr., Madison, Wis.), or by visual inspection.
The term “specificity” when used with respect to the antimicrobial activity of a peptide indicates that the peptide preferentially inhibits growth and/or proliferation and/or kills a particular microbial species as compared to other related and/or unrelated microbes. In certain embodiments the preferential inhibition or killing is at least 10% greater (e.g., LD50 is 10% lower), preferably at least 20%, 30%, 40%, or 50%, more preferably at least 2-fold, at least 5-fold, or at least 10-fold greater for the target species.
“Treating” or “treatment” of a condition as used herein may refer to preventing the condition, slowing the onset or rate of development of the condition, reducing the risk of developing the condition, preventing or delaying the development of symptoms associated with the condition, reducing or ending symptoms associated with the condition, generating a complete or partial regression of the condition, or some combination thereof.
The term “consisting essentially of” when used with respect to an antimicrobial peptide (AMP) or AMP motif as described herein, indicates that the peptide or peptides encompassed by the library or variants, analogues, or derivatives thereof possess substantially the same or greater antimicrobial activity and/or specificity as the referenced peptide. In certain embodiments substantially the same or greater antimicrobial activity indicates at least 80%, preferably at least 90%, and more preferably at least 95% of the anti microbial activity of the referenced peptide(s) against a particular bacterial species (e.g., S. mutans).
The term “porphyrinic macrocycle” refers to a porphyrin or porphyrin derivative. Such derivatives include porphyrins with extra rings ortho-fused, or orthoperifused, to the porphyrin nucleus, porphyrins having a replacement of one or more carbon atoms of the porphyrin ring by an atom of another element (skeletal replacement), derivatives having a replacement of a nitrogen atom of the porphyrin ring by an atom of another element (skeletal replacement of nitrogen), derivatives having substituents other than hydrogen located at the peripheral (meso-, .beta.-) or core atoms of the porphyrin, derivatives with saturation of one or more bonds of the porphyrin (hydroporphyrins, e.g., chlorins, bacteriochlorins, isobacteriochlorins, decahydroporphyrins, corphins, pyrrocorphins, etc.), derivatives obtained by coordination of one or more metals to one or more porphyrin atoms (metalloporphyrins), derivatives having one or more atoms, including pyrrolic and pyrromethenyl units, inserted in the porphyrin ring (expanded porphyrins), derivatives having one or more groups removed from the porphyrin ring (contracted porphyrins, e.g., corrin, corrole) and combinations of the foregoing derivatives (e.g. phthalocyanines, porphyrazines, naphthalocyanines, subphthalocyanines, and porphyrin isomers). Certain porphyrinic macrocycles comprise at least one 5-membered ring.
As used herein, an “antibody” refers to a protein consisting of one or more polypeptides substantially encoded by immunoglobulin genes or fragments of immunoglobulin genes. The recognized immunoglobulin genes include the kappa, lambda, alpha, gamma, delta, epsilon and mu constant region genes, as well as myriad immunoglobulin variable region genes. Light chains are classified as either kappa or lambda. Heavy chains are classified as gamma, mu, alpha, delta, or epsilon, which in turn define the immunoglobulin classes, IgG, IgM, IgA, IgD and IgE, respectively.
A typical immunoglobulin (antibody) structural unit is known to comprise a tetramer. Each tetramer is composed of two identical pairs of polypeptide chains, each pair having one “light” (about 25 kD) and one “heavy” chain (about 50-70 kD). The N-terminus of each chain defines a variable region of about 100 to 110 or more amino acids primarily responsible for antigen recognition. The terms variable light chain (VL) and variable heavy chain (VH) refer to these light and heavy chains respectively.
Antibodies exist as intact immunoglobulins or as a number of well characterized fragments produced by digestion with various peptidases. Thus, for example, pepsin digests an antibody below the disulfide linkages in the hinge region to produce F(ab)′2, a dimer of Fab which itself is a light chain joined to VH—CH1 by a disulfide bond. The F(ab)′2 may be reduced under mild conditions to break the disulfide linkage in the hinge region thereby converting the (Fab′)2 dimer into an Fab′ monomer. The Fab′ monomer is essentially an Fab with part of the hinge region (see, Fundamental Immunology, W. E. Paul, ed., Raven Press, N.Y. (1993), for a more detailed description of other antibody fragments). While various antibody fragments are defined in terms of the digestion of an intact antibody, one of skill will appreciate that such Fab′ fragments may be synthesized de novo either chemically or by utilizing recombinant DNA methodology. Thus, the term antibody, as used herein also includes antibody fragments either produced by the modification of whole antibodies or synthesized de novo using recombinant DNA methodologies, including, but are not limited to, Fab′2, IgG, IgM, IgA, scFv, dAb, nanobodies, unibodies, and diabodies.
In certain embodiments antibodies and fragments of the present invention can be bispecific. Bispecific antibodies or fragments can be of several configurations. For example, bispecific antibodies may resemble single antibodies (or antibody fragments) but have two different antigen binding sites (variable regions). In various embodiments bispecific antibodies can be produced by chemical techniques (Kranz et al. (1981) Proc. Natl. Acad. Sci., USA, 78: 5807), by “polydoma” techniques (see, e.g., U.S. Pat. No. 4,474,893), or by recombinant DNA techniques. In certain embodiments bispecific antibodies of the present invention can have binding specificities for at least two different epitopes, at least one of which is an epitope of a microbial organism. The microbial binding antibodies and fragments can also be heteroantibodies. Heteroantibodies are two or more antibodies, or antibody binding fragments (e.g., Fab) linked together, each antibody or fragment having a different specificity.
The term “STAMP” refers to Specifically Targeted Anti-Microbial Peptides. An MH-STAMP is a STAMP bearing two or more targeting domains (i.e., a multi-headed STAMP).
In various embodiments the amino acid abbreviations shown in Table 1 are used herein.
In various embodiments this invention is based on the development of a method for the rapid identification and synthesis of small peptides from sequenced genomes for the purposes of quickly screening these molecules for diverse biological activities. Previously, small secreted peptides had to be identified by direct collection (purification of spent microbial growth medium or biological tissue/fluid), or by identification through differential microarray analysis or as a by-product of genetic operon characterization. Both are multi-step processes that terminate at peptide identification; several separate enterprises are required to synthesize or sequence any peptides for characterization. Additionally, because of their small size and lack of protein domain homologies, small peptides are frequently overlooked when describing biological systems, though many organisms contain numerous peptide-sized open reading frames (ORFs).
Genomic sequence analysis tools already in the public domain and high-throughput solid phase peptide chemistry were used to rapidly identify and synthesize biologically active peptides. Using sequences and sometimes annotated genomes, genomes were scanned, by hand or with a search algorithm, for ORFs predicted to encode peptides of less than for example, 50-60 amino acids (ignoring small tRNA ORFs or other well characterized genes).
Once noted, these peptides were batch synthesized on a multiplex peptide synthesizer, yielding 5-10 mg of each peptide that could readily be screened for biological activity (e.g., binding activity and/or antimicrobial activity.
Accordingly, in certain embodiments, this invention pertains to the identification of novel peptides (see, e.g., Table 2) that specifically or preferentially bind particular microorganisms (e.g., bacteria) and/or that have antimicrobial activity. In certain embodiments these peptides can be attached to effectors (e.g., drugs, labels, etc.) and used as targeting moieties thereby providing a chimeric moiety that preferentially or specifically delivers the effector to a target microorganism, a population of target microorganisms, a microbial film comprising the target microorganism(s), a biofilm comprising the target microorganism(s), and the like.
In certain embodiments these peptides can be exploited for their antimicrobial activity to inhibit the growth or proliferation of a microorganism and/or to inhibit the formation and/or growth of a biofilm comprising the microorganism. These antimicrobial peptides can be used alone, in conjunction with other agents (e.g., antibacterial agents), and/or they can be coupled to a targeting moiety to provide a chimeric moiety that preferentially directs the antimicrobial peptide to a target tissue and/or to a target organism (e.g., a bacterium, a population of target microorganisms, a microbial film, a biofilm, and the like).
In certain embodiments the antimicrobial peptides and/or the chimeric moieties described herein can be formulated with a pharmaceutically acceptable carrier to form a pharmacological composition.
The amino acid sequences of illustrative peptides of this invention having antimicrobial and/or targeting activity against methicillin resistant Streptococcus mutans, Streptococcus pyogenes, and/or Treponema denticola is shown in Table 2. As with the other peptides described herein, it will be recognized that these peptides can comprise all “L” form residues, all “D” form residues, mixtures of “L” and “D” residues, and beta peptide sequences. It will also be appreciated in addition to the D-form and L-form and beta-peptide sequences this invention also contemplates retro and retro-inverso forms of each of these peptides. In retro forms, the direction of the sequence is reversed. In inverse forms, the chirality of the constituent amino acids is reversed (i.e., L form amino acids become D form amino acids and D form amino acids become L form amino acids). In the retro-inverso form, both the order and the chirality of the amino acids is reversed. Thus, for example, a retro form of the of the peptide Smu11 (MKNLIETVEKFLTYSDEKLEELAKKNQALREEISRQKSK, SEQ ID NO:11) has the sequence KSKQRSIEERLAQNKKALEELKEDSYTLFKEVTEILNKM (SEQ ID NO:10). Where the Smu11 peptide comprises all L amino acids, the inverse form will comprise all D amino acids and the retro-inverso (retro-inverse) form will have the sequence of SEQ ID NO:10 and comprise all D form amino acids. Also contemplated are peptides having the amino acid sequences or retro amino acid sequences of the peptides in Table 2 (or the other tables shown herein) and comprising one, two, three, four, five, six, seven, eight, nine, or ten conservative substitutions, but retaining substantially the same binding and/or antimicrobial activity. Also contemplated are peptides having the amino acid sequences or retro amino acid sequences of the peptides in Table 2 (or other tables herein) and comprising one, two, three, four, five, six, seven, eight, nine, or ten deletions, but retaining substantially the same binding and/or antimicrobial activity.
In various embodiments, chimeric moieties comprising one or more of the targeting peptides found in Table 2 attached to one or more effectors (e.g., antimicrobial peptides as described herein) are contemplated. In various embodiments, one or more of the antimicrobial peptides found in Table 2 used as effectors or attached to one or more targeting moieties (e.g., targeting peptides, targeting antibodies, and the like) to form chimeric moieties are contemplated.
When exploited for their targeting activity, the novel targeting peptides described herein (see, e.g., Table 2) can be used to preferentially or specifically deliver an effector to a microorganism (e.g., a bacterium, a fungus, a protozoan, a yeast, an algae, etc.), to a bacterial film comprising the microorganism, to a biofilm comprising the microorganism, and the like. Where the effector comprises an epitope tag and/or a detectable label, binding of the targeting moiety provides an indication of the presence and/or location, and/or quantity of the target (e.g., target microorganism). Thus targeting moieties are thus readily adapted for use in in vivo diagnostics, and/or ex vivo assays. Moreover, because of small size and good stability, the microorganism binding peptides are well suited for microassay systems (e.g., microfluidic assays (Lab on a Chip), microarray assays, and the like).
In certain embodiments the microorganism binding peptides (targeting peptides) can be attached to an effector that has antimicrobial activity (e.g., an antimicrobial peptide, an antibacterial and/or antifungal, a vehicle that contains an antibacterial or antifungal, etc. In various embodiments these chimeric moieties can be used in vivo, or ex vivo to preferentially inhibit or kill the target organism(s).
In certain embodiments the targeting peptides can be used in various pre-targeting protocols. In pre-targeting protocols, a chimeric molecule is utilized comprising a primary targeting species (e.g. a microorganism-binding peptide) that specifically binds the desired target (e.g. a bacterium) and an effector that provides a binding site that is available for binding by a subsequently administered second targeting species. Once sufficient accretion of the primary targeting species (the chimeric molecule) is achieved, a second targeting species comprising (i) a diagnostic or therapeutic agent and (ii) a second targeting moiety, that recognizes the available binding site of the primary targeting species, is administered.
An illustrative example of a pre-targeting protocol is the biotin-avidin system for administering a cytotoxic radionuclide to a tumor. In a typical procedure, a monoclonal antibody targeted against a tumor-associated antigen is conjugated to avidin and administered to a patient who has a tumor recognized by the antibody. Then the therapeutic agent, e.g., a chelated radionuclide covalently bound to biotin, is administered. The radionuclide, via its attached biotin is taken up by the antibody-avidin conjugate pretargeted at the tumor. Examples of pre-targeting biotin/avidin protocols are described, for example, in Goodwin et al., U.S. Pat. No. 4,863,713; Goodwin et al. (1988) J. Nucl. Med. 29: 226; Hnatowich et al. (1987) J. Nucl. Med. 28: 1294; Oehr et al. (1988) J. Nucl. Med. 29: 728; Klibanov et al. (1988) J. Nucl. Med. 29: 1951; Sinitsyn et al. (1989) J. Nucl. Med. 30: 66; Kalofonos et al. (1990) J. Nucl. Med. 31: 1791; Schechter et al. (1991) Int. J. Cancer 48:167; Paganelli et al. (1991) Cancer Res. 51: 5960; Paganelli et al. (1991) Nucl. Med. Commun. 12: 211; Stickney et al. (1991) Cancer Res. 51: 6650; and Yuan et al. (1991) Cancer Res. 51:3119.
It will be recognized that the tumor-specific antibody used for cancer treatments can be replaced with a microorganism binding peptide of the present invention and similar pre-targeting strategies can be used to direct labels, antibiotics, and the like to the target organism(s).
Three-step pre-targeting protocols in which a clearing agent is administered after the first targeting composition has localized at the target site also have been described. The clearing agent binds and removes circulating primary conjugate which is not bound at the target site, and prevents circulating primary targeting species (antibody-avidin or conjugate, for example) from interfering with the targeting of active agent species (biotin-active agent conjugate) at the target site by competing for the binding sites on the active agent-conjugate. When antibody-avidin is used as the primary targeting moiety, excess circulating conjugate can be cleared by injecting a biotinylated polymer such as biotinylated human serum albumin. This type of agent forms a high molecular weight species with the circulating avidin-antibody conjugate which is quickly recognized by the hepatobiliary system and deposited primarily in the liver.
Examples of these protocols are disclosed, e.g., in PCT Application No. WO 93/25240; Paganelli et al. (1991) Nucl. Med. Comm., 12: 211-234; Oehr et al. (1988) J. Nucl. Med., 29: 728-729; Kalofonos et al. (1990) J. Nucl. Med., 31: 1791-1796; Goodwin et al. (1988) J. Nucl. Med., 29: 226-234; and the like).
These applications of microorganism binding peptides of this invention are intended to be illustrative and not limiting. Using the teaching provided herein, other uses will be recognized by one of skill in the art.
Uses of Antimicrobial Peptides.When exploited for their antimicrobial activity, the novel antimicrobial peptides described herein (see, e.g., Table 2) can be used to inhibit the growth and/or proliferation of a microbial species and/or the growth or proliferation of a biofilm comprising the microbial species. In various embodiments the peptides can be formulated individually, in combination with each other, in combination with other antimicrobial peptides, and/or in combination with various antibacterial agents to provide antimicrobial reagents and/or pharmaceuticals.
In various embodiments, the antimicrobial peptides described herein can be formulated individually, in combination with each other, in combination with other antimicrobial peptides, and/or in combination with various antibiotic (e.g., antibacterial) agents in “home healthcare” formulations. Such formulations include, but are not limited to toothpaste, mouthwash, tooth whitening strips or solutions, contact lens storage, wetting, or cleaning solutions, dental floss, toothpicks, toothbrush bristles, oral sprays, oral lozenges, nasal sprays, aerosolizers for oral and/or nasal application, wound dressings (e.g., bandages), and the like.
In various embodiments the antimicrobial peptides described herein can be formulated individually, in combination with each other, in combination with other antimicrobial peptides, and/or in combination with various antibiotic (e.g., antibacterial) agents in various cleaning and/or sterilization formulations for use in the home, workplace, clinic, or hospital.
In certain embodiments the antimicrobial peptides described herein are attached to one or more targeting moieties to specifically and/or to preferentially deliver the peptide(s) to a target (e.g. a target microorganism, biofilm, bacterial film, particular tissue, etc.).
Other possible uses of the targeting and/or antimicrobial peptides disclosed herein include, but are not limited to biofilm dispersal, biofilm retention, biofilm formation, anti-biofilm formation, cell agglutination, induction of motility or change in motility type, chemoattractant or chemorepellent, extracellular signal for sporogenesis or other morphological change, induction or inhibition of virulence gene expression, utilized as extracellular scaffold, adhesin or binding site, induction or suppression of host immune response, induction or suppression of bacterial/fungal antimicrobial molecule production, quorum-sensing, induction of swarming behavior, apoptosis or necrosis inducing in eukaryotic cells, affecting control of or inducing the initiation of cell cycle in eukaryotes, in archaea or prokaryotes, induces autolysis or programmed cell death, inhibition of phage/virus attachment or replication, evasion of innate immunity, induction or inhibition of genetic transformation or transduction competence, induction or inhibition of pilus-mediated conjugation, induction or inhibition of mating behavior in bacteria and fungi, induction or inhibition of nodule formation or metabolic compartmentalization, metal, ion, or nutrient binding, acquisition or inhibition of metal, ion, or nutrient binding and acquisition, and the like.
These applications of the peptides described herein are intended to be illustrative and not limiting. Using the teaching provided herein, other uses will be recognized by one of skill in the art.
Design and Construction of Chimeric Moieties.In various embodiments this invention provides chimeric moieties comprising one or more targeting moieties attached to one or more effectors. The targeting moieties are typically selected to preferentially bind to a target microorganism (e.g., bacteria, virus, fungi, yeast, alga, protozoan, etc.), or group of microorganisms (e.g., gram-negative or gram-positive bacteria, particular genus, particular species, etc.) In certain embodiments the targeting moiety comprises one or more of the targeting peptides shown in Table 2, and/or Table 4 and/or Table 6. In certain embodiments the targeting moiety comprises non-peptide moieties (e.g., antibodies, receptor, receptor ligand, lectin, and the like).
The effector typically comprises one or more moieties whose activity is to be delivered to the target microorganism(s), and/or to a biofilm comprising the target microorganism(s), and/or to a cell or tissue comprising the target microorganism(s), and the like. In certain embodiments the targeting moiety comprises one or more antimicrobial peptide(s) as described herein (see, e.g., antimicrobial peptides in Table 2, and/or Table 8, and/or Table 9, and/or Table 10), an antibiotic (including, but not limited to a steroid antibiotic) (see, e.g., Table 7), a detectable label, a porphyrin, a photosensitizing agent, an epitope tag, a lipid or liposome, a nanoparticle, a dendrimer, and the like.
In certain embodiments one or more targeting moieties are attached to a single effector (see, e.g.
Targeting Moieties.
In various embodiments this invention provides targeting moieties that preferentially and/or specifically bind to a microorganism (e.g., a bacterium, a fungus, a yeast, etc.). One or more such targeting moieties can be attached to one or more effectors to provide chimeric moieties that are capable of delivering the effector(s) to a target (e.g., a bacterium, a fungus, a yeast, a biofilm comprising the bacterium or fungus or yeast, etc.).
In various embodiments, targeting moieties include, but are not limited to peptides that preferentially bind particular microorganisms (e.g., bacteria, fungi, yeasts, protozoa, algae, viruses, etc.) or groups of such microorganisms, antibodies that bind particular microorganisms or groups of microorganisms, receptor ligands that bind particular microorganisms or groups of microorganisms, porphyrins (e.g., metalloporphyrins), lectins that bind particular microorganisms or groups of microorganisms, and the like. As indicated, it will be appreciated that references to microorganisms or groups of microorganism include bacteria or groups of bacteria, viruses or groups of viruses, yeasts or groups of yeasts, protozoa or groups of protozoa, viruses or groups of viruses, and the like.
Targeting Peptides.
In certain embodiments the chimeric constructs described herein comprise a targeting moiety that is or comprises a targeting peptide. Typically the targeting peptides bind particular bacteria, and/or fungi, and/or yeasts, and/or algae, and/or viruses and/or bind particular groups of bacteria, and/or groups of fungi, and/or groups of yeasts, and/or groups of algae. The targeting peptides provided can be used to effectively deliver one or more effectors to or into a target microorganism. Illustrative targeting peptides include, but are not limited to the targeting peptides found in Table 2.
Other suitable targeting peptides include the peptides that have been identified as binding to particular target organisms as shown in Table 4 and/or Table 4.
As described above, in certain embodiments of the present invention, the targeting moiety can comprise targeting peptide capable of binding, specifically binding, or preferentially binding to a microorganism, e.g., a target microbial organism. In one embodiment, the targeting peptide be identified via screening peptide libraries. For example, a phage display peptide library can be screened against a target microbial organism or a desired antigen or epitope thereof. Any peptide identified through such screening can be used as a targeting peptide for the target microbial organism. Illustrative additional targeting peptides are shown in Table 4.
In certain embodiments the targeting moieties can comprise other entities, particularly when utilized with an antimicrobial peptide as described, for example, in Table 2. Illustrative targeting moieties can include a polypeptide, a peptide, a small molecule, a ligand, a receptor, an antibody, a protein, or portions thereof that specifically interact with a target microbial organism, e.g., the cell surface appendages such as flagella and pili, and surface exposed proteins, lipids and polysaccharides of a target microbial organism.
Targeting Antibodies.
In certain embodiments the targeting moieties can comprise one or more antibodies that bind specifically or preferentially a microorganism or group of microorganisms (e.g., bacteria, fungi, yeasts, protozoa, viruses, algae, etc.). The antibodies are selected to bind an epitope characteristic or the particular target microorganism(s). In various embodiments such epitopes or antigens are typically is gram-positive or gram-negative specific, or genus-specific, or species-specific, or strain specific and located on the surface of a target microbial organism. The antibody that binds the epitope or antigen can direct an anti-microbial peptide moiety or other effector to the site. Furthermore, in certain embodiments the antibody itself can provide anti-microbial activity in addition to the activity provided by effector moiety since the antibody may engage an immune system effector (e.g., a T-cell) and thereby elicit an antibody-associated immune response, e.g., a humoral immune response.
Antibodies that bind particular target microorganisms can be made using any methods readily available to one skilled in the art. For example, as described in U.S. Pat. No. 6,231,857 (incorporated herein by reference) three monoclonal antibodies, i.e., SWLA1, SWLA2, and SWLA3 have been made against S. mutans. Monoclonal antibodies obtained from non-human animals to be used in a targeting moiety can also be humanized by any means available in the art to decrease their immunogenicity and increase their ability to elicit anti-microbial immune response of a human. Illustrative microorganisms and/or targets to which antibodies may be directed are shown, for example, in Tables 5.
Various forms of antibody include, without limitation, whole antibodies, antibody fragments (e.g., (Fab′)2, Fab′, etc.), single chain antibodies (e.g., scFv), minibodies, Di-miniantibody, Tetra-miniantibody, (scFv)2, Diabody, scDiabody, Triabody, Tetrabody, Tandem diabody, VHH, nanobodies, affibodies, unibodies, and the like.
Methods of making such antibodies are well known to those of skill in the art. In various embodiments, such methods typically involve providing the microorganism, or a component thereof for use as an antigen to raise an immune response in an organism or for use in a screening protocol (e.g., phage or yeast display).
For example, polyclonal antibodies are typically raised by one or more injections (e.g. subcutaneous or intramuscular injections) of the target microorganism(s) or components thereof into a suitable non-human mammal (e.g., mouse, rabbit, rat, etc.).
If desired, the immunizing microorganism or antigen derived therefrom can be administered with or coupled to a carrier protein by conjugation using techniques that are well-known in the art. Such commonly used carriers which are chemically coupled to the peptide include keyhole limpet hemocyanin (KLH), thyroglobulin, bovine serum albumin (BSA), and tetanus toxoid. The coupled peptide is then used to immunize the animal (e.g. a mouse or a rabbit).
The antibodies are then obtained from blood samples taken from the mammal. The techniques used to develop polyclonal antibodies are known in the art (see, e.g., Methods of Enzymology, “Production of Antisera With Small Doses of Immunogen: Multiple Intradermal Injections”, Langone, et al. eds. (Acad. Press, 1981)). Polyclonal antibodies produced by the animals can be further purified, for example, by binding to and elution from a matrix to which the peptide to which the antibodies were raised is bound. Those of skill in the art will know of various techniques common in the immunology arts for purification and/or concentration of polyclonal antibodies, as well as monoclonal antibodies see, for example, Coligan, et al. (1991) Unit 9, Current Protocols in Immunology, Wiley Interscience).
In certain embodiments the antibodies produced will be monoclonal antibodies (“mAb's”). The general method used for production of hybridomas secreting mAbs is well known (Kohler and Milstein (1975) Nature, 256:495
Antibody fragments, e.g. single chain antibodies (scFv or others), can also be produced/selected using phage display and/or yeast display technology. The ability to express antibody fragments on the surface of viruses that infect bacteria (bacteriophage or phage) or yeasts makes it possible to isolate a single binding antibody fragment, e.g., from a library of greater than 1010 nonbinding clones. To express antibody fragments on the surface of phage (phage display) or yeast, an antibody fragment gene is inserted into the gene encoding a phage surface protein (e.g., pIII) and the antibody fragment-pIII fusion protein is displayed on the phage surface (McCafferty et al. (1990) Nature, 348: 552-554; Hoogenboom et al. (1991) Nucleic Acids Res. 19: 4133-4137).
Since the antibody fragments on the surface of the phage or yeast are functional, phage bearing antigen binding antibody fragments can be separated from non-binding phage by antigen affinity chromatography (McCafferty et al. (1990) Nature, 348: 552-554). Depending on the affinity of the antibody fragment, enrichment factors of 20 fold-1,000,000 fold are obtained for a single round of affinity selection.
Human antibodies can be produced without prior immunization by displaying very large and diverse V-gene repertoires on phage (Marks et al. (1991) J. Mol. Biol. 222: 581-597.
In certain embodiments, nanobodies can be used as targeting moieties. Methods of making VhH (nanobodies) are also well known to those of skill in the art. The Camelidae heavy chain antibodies are found as homodimers of a single heavy chain, dimerized via their constant regions. The variable domains of these camelidae heavy chain antibodies are referred to as VHH domains or VHH, and can be either used per se as nanobodies and/or as a starting point for obtaining nanobodies. Isolated VHH retain the ability to bind antigen with high specificity (see, e.g., Hamers-Casterman et al. (1993) Nature 363: 446-448). In certain embodiments such VHH domains, or nucleotide sequences encoding them, can be derived from antibodies raised in Camelidae species, for example in camel, dromedary, llama, alpaca and guanaco. Other species besides Camelidae (e.g. shark, pufferfish) can produce functional antigen-binding heavy chain antibodies, from which (nucleotide sequences encoding) such naturally occurring VHH can be obtained, e.g. using the methods described in U.S. Patent Publication US 2006/0211088.
In various embodiments, for use in therapy, human proteins are preferred, primarily because they are not as likely to provoke an immune response when administered to a patient. Comparisons of camelid VHH with the VH domains of human antibodies reveals several key differences in the framework regions of the camelid VHH domain corresponding to the VH/VL interface of the human VH domains. Mutation of these human residues to VHH resembling residues has been performed to produce “camelized” human VH domains that retain antigen binding activity, yet have improved expression and solubility.
Libraries of single VH domains have also been derived for example from VH genes amplified from genomic DNA or from mRNA from the spleens of immunized mice and expressed in E. coli (Ward et al. (1989) Nature 341: 544-546) and similar approaches can be performed using the VH domains and/or the VL domains described herein. The isolated single VH domains are called “dAbs” or domain antibodies. A “dAb” is an antibody single variable domain (VH or VL) polypeptide that specifically binds antigen. A “dAb” binds antigen independently of other V domains; however, as the term is used herein, a “dAb” can be present in a homo- or heteromultimer with other VH or VL domains where the other domains are not required for antigen binding by the dAb, i.e., where the dAb binds antigen independently of the additional VH or VL domains.
As described in U.S. Patent Publication US 2006/0211088 methods are known for the cloning and direct screening of immunoglobulin sequences (including but not limited to multivalent polypeptides comprising: two or more variable domains—or antigen binding domains—and in particular VH domains or VHH domains; fragments of VL, VH or VHH domains, such as CDR regions, for example CDR3 regions; antigen-binding fragments of conventional 4-chain antibodies such as Fab fragments and scFv's, heavy chain antibodies and domain antibodies; and in particular of VH sequences, and more in particular of VHH sequences) that can be used as part of and/or to construct such nanobodies.
Methods and procedures for the production of VHH/nanobodies can also be found for example in WO 94/04678, WO 96/34103, WO 97/49805, WO 97/49805 WO 94/25591, WO 00/43507 WO 01/90190, WO 03/025020, WO 04/062551, WO 04/041863, WO 04/041865, WO 04/041862, WO 04/041867, PCT/BE2004/000159, Hamers-Casterman et al. (1993) Nature 363: 446; Riechmann and Muyldermans (1999) J. Immunological Meth., 231: 25-38; Vu et al. (1997) Molecular Immunology, 34(16-17): 1121-1131; Nguyen et al. (2000) EMBO J., 19(5): 921-930; Arbabi Ghahroudi et al. (19997) FEBS Letters 414: 521-526; van der Linden et al. (2000) J. Immunological Meth., 240: 185-195; Muyldermans (2001) Rev. Molecular Biotechnology 74: 277-302; Nguyen et al. (2001) Adv. Immunol. 79: 261, and the like, which are all incorporated herein by reference.
In certain embodiments the antibody targeting moiety is a unibody. Unibodies provide an antibody technology that produces a stable, smaller antibody format with an anticipated longer therapeutic window than certain small antibody formats. In certain embodiments unibodies are produced from IgG4 antibodies by eliminating the hinge region of the antibody. Unlike the full size IgG4 antibody, the half molecule fragment is very stable and is termed a uniBody. Halving the IgG4 molecule left only one area on the UniBody that can bind to a target. Methods of producing unibodies are described in detail in PCT Publication WO2007/059782, which is incorporated herein by reference in its entirety (see, also, Kolfschoten et al. (2007) Science 317: 1554-1557).
Affibody molecules are class of affinity proteins based on a 58-amino acid residue protein domain, derived from one of the IgG-binding domains of staphylococcal protein A. This three helix bundle domain has been used as a scaffold for the construction of combinatorial phagemid libraries, from which Affibody variants that target the desired molecules can be selected using phage display technology (see, e.g., Nord et al. (1997) Nat. Biotechnol. 15: 772-777; Ronmark et al. (2002) Eur. J. Biochem., 269: 2647-2655.). Details of Affibodies and methods of production are known to those of skill (see, e.g., U.S. Pat. No. 5,831,012 which is incorporated herein by reference in its entirety).
It will also be recognized that antibodies can be prepared by any of a number of commercial services (e.g., Berkeley antibody laboratories, Bethyl Laboratories, Anawa, Eurogenetec, etc.).
Illustrative antibodies that bind various microorganisms are shown in Table 5.
In addition, antibodies (targeting moieties) that bind other microorganisms can readily be produced using, for example, the methods described above.
Porphyrins.
In certain embodiments porphyrins, or other photosensitizing agents, can be used as targeting moieties in the constructs described herein. In particular, metalloporphyrins, particularly a number of non-iron metalloporphyrins mimic heme in their molecular structure and are actively accumulated by bacteria via high affinity heme-uptake systems. The same uptake systems can be used to deliver antibiotic-porphyrin and antibacterial-porphyrin conjugates. Illustrative targeting porphyrins suitable for this purpose are described in U.S. Pat. No. 6,066,628 and shown herein, for example, in
For example, certain artificial (non-iron) metalloporphyrins (MPs) (Ga-IX, Mn-IX,) are active against Gram-negative and Gram-positive bacteria and acid-fast bacilli (e.g., Y. enterocolitica, N. meningitides, S. marcescens, E. coli, P. mirabills, K. pneumoniae, K. oxytoca, Ps. aeruginosa, C. freundii, E. aerogenes, F. menigosepticum, S. aureus, B. subtilis, S. pyogenes A, E. faecalis, M. smegmatis, M. bovis, M. tuber., S. crevisiae) as described in Tables 1-5 of U.S. Pat. No. 6,066,628. These MPs can be used as targeting moieties against these microorganisms.
Similarly, some MPs are also growth-inhibitory against yeasts, indicating their usefulness targeting moieties to target Candida species (e.g., Candida albicans, C. krusei, C. pillosus, C. glabrata, etc.) and other mycoses including but not limited to those caused by as Trichophyton, Epidermophyton, Histoplasma, Aspergillus, Cryptococcus, and the like.
Porphyrins, and other photosensitizers, also have antimicrobial activity. Accordingly, in certain embodiments, the porphyrins, or other photosensitizers, can be used as effectors (e.g., attached to targeting peptides as described herein). In various embodiments the porphyrins or other photosensitizers can provide a dual functionality, e.g., as a targeting moiety and an antimicrobial and can be attached to a targeting peptide and/or to an antimicrobial peptide as described herein.
Illustrative porphyrins and other photosensitizers are shown in
Pheromones.
In certain embodiments, pheromones from microorganisms can be used as targeting moieties. Illustrative pheromones from bacteria and fungi are shown in Table 6. In certain embodiments, chimeric moieties are contemplated comprising a targeting moiety comprising or consisting of the amino acid sequence (or retro or retro-inverso or beta) sequence of a peptide shown in Table 6 attached to one or more of the peptides shown in Table 2.
Effectors.
Any of a wide number of effectors can be coupled to targeting moieties as described herein to preferentially deliver the effector to a target organism and/or tissue. Illustrative effectors include, but are not limited to detectable labels, small molecule antibiotics, antimicrobial peptides, porphyrins or other photosensitizers, epitope tags/antibodies for use in a pretargeting protocol, microparticles and/or microcapsules, nanoparticles and/or nanocapsules, “carrier” vehicles including, but not limited to lipids, liposomes, dendrimers, cholic acid-based peptide mimics or other peptide mimics, steroid antibiotics, and the like.
Detectable Labels.
In certain embodiments chimeric moieties are provided comprising a targeting moiety (e.g. as described in Table 2) attached directly or through a linker to a detectable label. Such chimeric moieties are effective for detecting the presence and/or quantity, and/or location of the microorganism(s) to which the targeting moiety is directed. Similarly these chimeric moieties are useful to identify cells and/or tissues and/or food stuffs and/or other compositions that are infected with the targeted microorganism(s).
Detectable labels suitable for use in such chimeric moieties include any composition detectable by spectroscopic, photochemical, biochemical, immunochemical, electrical, optical, or chemical means. Illustrative useful labels include, but are not limited to, biotin for staining with labeled streptavidin conjugates, avidin or streptavidin for labeling with biotin conjugates fluorescent dyes (e.g., fluorescein, texas red, rhodamine, green fluorescent protein, and the like, see, e.g., Molecular Probes, Eugene, Oreg., USA), radiolabels (e.g., 3H, 125I, 35S, 14C, 32P, 99Tc, 203Pb, 67Ga, 68Ga, 72As, 111In, 113mIn, 97Ru, 62Cu, 641Cu, 52Fe, 52mMn, 51Cr, 186Re, 188Re, 77As, 90Y, 67Cu, 169Er, 121Sn, 127Te, 142Pr, 143Pr, 198Au, 199Au, 161Tb, 109Pd, 165Dy, 149Pm, 151Pm, 153Sm, 157Gd, 159Gd, 166Ho, 172Tm, 169Yb, 175Yb, 177Lu, 105Rh, 111Ag, and the like), enzymes (e.g., horse radish peroxidase, alkaline phosphatase and others commonly used in an ELISA), various colorimetric labels, magnetic or paramagnetic labels (e.g., magnetic and/or paramagnetic nanoparticles), spin labels, radio-opaque labels, and the like. Patents teaching the use of such labels include, for example, U.S. Pat. Nos. 3,817,837; 3,850,752; 3,939,350; 3,996,345; 4,277,437; 4,275,149; and 4,366,241.
It will be recognized that fluorescent labels are not to be limited to single species organic molecules, but include inorganic molecules, multi-molecular mixtures of organic and/or inorganic molecules, crystals, heteropolymers, and the like. Thus, for example, CdSe—CdS core-shell nanocrystals enclosed in a silica shell can be easily derivatized for coupling to a biological molecule (Bruchez et al. (1998) Science, 281: 2013-2016). Similarly, highly fluorescent quantum dots (zinc sulfide-capped cadmium selenide) have been covalently coupled to biomolecules for use in ultrasensitive biological detection (Warren and Nie (1998) Science, 281: 2016-2018).
In various embodiments spin labels are provided by reporter molecules with an unpaired electron spin which can be detected by electron spin resonance (ESR) spectroscopy. Illustrative spin labels include organic free radicals, transitional metal complexes, particularly vanadium, copper, iron, and manganese, and the like. Exemplary spin labels include, for example, nitroxide free radicals.
Means of detecting such labels are well known to those of skill in the art. Thus, for example, where the label is a radioactive label, means for detection include a scintillation counter or photographic film as in autoradiography. Where the label is a fluorescent label, it may be detected by exciting the fluorochrome with the appropriate wavelength of light and detecting the resulting fluorescence, e.g., by microscopy, visual inspection, via photographic film, by the use of electronic detectors such as charge coupled devices (CCDs) or photomultipliers and the like. Similarly, enzymatic labels may be detected by providing appropriate substrates for the enzyme and detecting the resulting reaction product. Finally, simple colorimetric labels may be detected simply by observing the color associated with the label.
Antibiotics.
In certain embodiments chimeric moieties are provided comprising a targeting moiety (e.g. as described in Table 2) attached directly or through a linker to a small molecule antibiotic and/or to a carrier (e.g., a lipid or liposome, a polymer, etc.) comprising a small molecule antibiotic (e.g., an antibiotics shown in Table 7).
Porphyrins and Non-Porphyrin Photosensitizers.
In certain embodiments, porphyrins and other photosensitizers can be used as targeting moieties and/or as effectors in the methods and compositions of this invention. A photosensitizer is a drug or other chemical that increases photosensitivity of the organism (e.g., bacterium, yeast, fungus, etc.). As targeting moieties the photosensitizers (e.g., porphyrins) are preferentially uptaken by the target microorganisms and thereby facilitate delivery of the chimeric moiety to the target microorganism.
As effectors, photosensitizers can be useful in photodynamic antimicrobial chemotherapy (PACT). In various embodiments PACT utilizes photosensitizers and light (e.g., visible, ultraviolet, infrared, etc.) in order to give a phototoxic response in the target organism(s), often via oxidative damage.
Currently, the major use of PACT is in the disinfection of blood products, particularly for viral inactivation, although more clinically-based protocols are used, e.g. in the treatment of oral infection or topical infection. The technique has been shown to be effective in vitro against bacteria (including drug-resistant strains), yeasts, viruses, parasites, and the like.
Attaching a targeting moiety (e.g., a targeting peptide as shown in Table 2) to the photosensitizer, e.g., as described herein, provides a means of specifically or preferentially targeting the photosensitizer(s) to particular species or strains(s) of microorganism.
A wide range of photosensitizers, both natural and synthetic are known to those of skill in the art (see, e.g., Wainwright (1998) J. Antimicrob. Chemotherap. 42: 13-28). Photosensitizers are available with differing physicochemical make-up and light-absorption properties. In various embodiments photosensitizers are usually aromatic molecules that are efficient in the formation of long-lived triplet excited states. In terms of the energy absorbed by the aromatic-system, this again depends on the molecular structure involved. For example: furocoumarin photosensitizers (psoralens) absorb relatively high energy ultraviolet (UV) light (c. 300-350 nm), whereas macrocyclic, heteroaromatic molecules such as the phthalocyanines absorb lower energy, near-infrared light.
Illustrative photosensitizers include, but are not limited to porphyrinic macrocyles (especially porphyrins, chlorines, etc., see, e.g.,
For example, certain artificial (non-iron) metalloporphyrins (MPs) (Ga-IX, Mn-IX,) are active against Gram-negative and Gram-positive bacteria and acid-fast bacilli (e.g., Y enterocolitica, N. meningitides, S. marcescens, E. coli, P. mirabills, K. pneumoniae, K. oxytoca, Ps. aeruginosa, C. freundii, E. aerogenes, F. menigosepticum, S. aureus, B. subtilis, S. pyogenes A, E. faecalis, M. smegmatis, M. bovis, M. tuber., S. crevisiae) as described in Tables 1-5 of U.S. Pat. No. 6,066,628. These MPs can be used as targeting moieties against these microorganisms.
Similarly, some MPs are also growth-inhibitory against yeasts, indicating their usefulness targeting moieties to target Candida species (e.g., Candida albicans, C. krusei, C. pillosus, C. glabrata, etc.) and other mycoses including but not limited to those caused by as Trichophyton, Epidermophyton, Histoplasma, Aspergillus, Cryptococcus, and the like.
Other photosensitizers include, but are not limited to cyanines (see, e.g.,
In certain embodiments the photosensitizers are toxic or growth inhibitors without light activation. For example, some non-iron metalloporphyrins (MPs) (see, e.g.,
Typically, when activated by light, the toxicity or growth inhibition effect is substantially increased. Typically, they generate radical species that affect anything within proximity. In certain embodiments to get the best selectivity from targeted photosensitizers, anti-oxidants can be used to quench un-bound photosensitizers, limiting the damage only to cells where the conjugates have accumulated due to the targeting peptide. The membrane structures of the target cell act as the proton donors in this case.
In typical photodynamic antimicrobial chemotherapy (PACT) the targeted photosensitizer is “activated by the application of a light source (e.g., a visible light source, an ultraviolet light source, an infrared light source, etc.). PACT applications however need not be limited to topical use. Regions of the mouth, throat, nose, sinuses are readily illuminated. Similarly regions of the gut can readily be illuminated using endoscopic techniques. Other internal regions can be illumined using laparoscopic methods or during other surgical procedures. For example, in certain embodiments involving the insertion or repair or replacement of an implantable device (e.g., a prosthetic device) it contemplated that the device can be coated or otherwise contacted with a chimeric moiety comprising a targeting moiety attached to a photosensitizer as described herein. During the surgical procedure and/or just before closing, the device can be illuminated with an appropriate light source to activate the photosensitizer.
The targeted photosensitizers and uses thereof described herein are illustrative and not to be limiting. Using the teachings provided herein, other targeted photosensitizers and uses thereof will be available to one of skill in the art.
Antimicrobial Peptides.
In certain embodiments the chimeric moieties described herein include one or more antimicrobial peptides (e.g., certain peptides shown in Table 2 and/or Table 10) as effectors. Thus, for example, in certain embodiments, where the peptides described in Table 2 are exploited for their targeting ability, chimeric moieties are contemplated comprising one or more of the targeting peptides of Table 2 attached to one or more of the antimicrobial peptides of Table 10. In certain embodiments chimeric moieties are contemplated comprising one or more of the targeting peptides of Table 2 attached to one or more of the antimicrobial peptides of Table 2. In certain embodiments chimeric moieties are contemplated comprising other targeting moieties (e.g., porphyrins, antibodies, etc.) attached to one or more of the antimicrobial peptides of Table 2.
Antimicrobial peptides (also called host defense peptides) are an evolutionarily conserved component of the innate immune response and are found among all classes of life. Unmodified, these peptides are potent, broad spectrum antibiotics which demonstrate potential as novel therapeutic agents. Antimicrobial peptides have been demonstrated to kill Gram-negative and Gram-positive bacteria (including strains that are resistant to conventional antibiotics), mycobacteria (including Mycobacterium tuberculosis), enveloped viruses, and fungi.
Naturally-occurring antimicrobial peptides are typically short peptides, generally between 12 and 50 amino acids. These peptides often include two or more positively charged residues provided by arginine, lysine or, in acidic environments, histidine, and frequently a large proportion (generally >50%) of hydrophobic residues (see, e.g., Papagianni et al. (2003) Biotechnol Adv 21: 465; Sitaram and Nagaraj (2002) Curr Pharm Des 8: 727; Dun et al. (2006) Biochim. Biophys. Acta 1758: 1408-1425).
Frequently the secondary structures of these molecules follow 4 themes, including i) α-helical, ii) β-stranded due to the presence of 2 or more disulfide bonds, iii) β-hairpin or loop due to the presence of a single disulfide bond and/or cyclization of the peptide chain, and iv) extended. Many of these peptides are unstructured in free solution, and fold into their final configuration upon partitioning into biological membranes. The ability to associate with membranes is a definitive feature of antimicrobial peptides although membrane permeabilisation is not necessary. These peptides have a variety of antimicrobial activities ranging from membrane permeabilization to action on a range of cytoplasmic targets.
The modes of action by which antimicrobial peptides kill bacteria is varied and includes, but is not limited to disrupting membranes, interfering with metabolism, and targeting cytoplasmic components. In many cases the exact mechanism of killing is not known.
In various embodiments one or more antimicrobial peptides are used alone (e.g., as broad spectrum antimicrobials) and/or are provided as effectors attached to one or more targeting moieties thereby providing a narrower spectrum (directed) antimicrobial. In certain embodiments one or more antimicrobial peptides are provided as effectors attached to one or more targeting moieties and/or one or more effectors thereby providing a component of a multiple effector composition/strategy.
Suitable antimicrobial peptides for this use include, but are not limited to the antimicrobial peptides found in Table 2, and/or Table 9, and/or Table 10.
In certain embodiments peptides that induce alterations in phenotype or other biological activities can also be used as antimicrobial effector moieties. Illustrative alternative peptides are shown in Table 9.
Other illustrative antimicrobial peptides include, but are not limited to the AMPs of Table 10.
A number of antimicrobial peptides are also disclosed in U.S. Pat. Nos. 7,271,239, 7,223,840, 7,176,276, 6,809,181, 6,699,689, 6,420,116, 6,358,921, 6,316,594, 6,235,973, 6,183,992, 6,143,498, 6,042,848, 6,040,291, 5,936,063, 5,830,993, 5,428,016, 5,424,396, 5,032,574, 4,623,733, which are incorporated herein by reference for the disclosure of particular antimicrobial peptides.
Ligands.
In certain embodiments the effector can comprise one or more ligands, epitope tags, and/or antibodies. In certain embodiments preferred ligands and antibodies include those that bind to surface markers on immune cells. Chimeric moieties utilizing such antibodies as effector molecules act as bifunctional linkers establishing an association between the immune cells bearing binding partner for the ligand or antibody and the target microorganism(s).
The term “epitope tag” or “affinity tag” are used interchangeably herein, and as used refers to a molecule or domain of a molecule that is specifically recognized by an antibody or other binding partner. The term also refers to the binding partner complex as well. Thus, for example, biotin or a biotin/avidin complex are both regarded as an affinity tag. In addition to epitopes recognized in epitope/antibody interactions, affinity tags also comprise “epitopes” recognized by other binding molecules (e.g. ligands bound by receptors), ligands bound by other ligands to form heterodimers or homodimers, His6 bound by Ni-NTA, biotin bound by avidin, streptavidin, or anti-biotin antibodies, and the like.
Epitope tags are well known to those of skill in the art. Moreover, antibodies specific to a wide variety of epitope tags are commercially available. These include but are not limited to antibodies against the DYKDDDDK (SEQ ID NO:1928) epitope, c-myc antibodies (available from Sigma, St. Louis), the HNK-1 carbohydrate epitope, the HA epitope, the HSV epitope, the His4 (SEQ ID NO:1929), Hiss (SEQ ID NO:1930), and His6 (SEQ ID NO:1931) epitopes that are recognized by the His epitope specific antibodies (see, e.g., Qiagen), and the like. In addition, vectors for epitope tagging proteins are commercially available. Thus, for example, the pCMV-Tag1 vector is an epitope tagging vector designed for gene expression in mammalian cells. A target gene inserted into the pCMV-Tag1 vector can be tagged with the FLAG® epitope (N-terminal, C-terminal or internal tagging), the c-myc epitope (C-terminal) or both the FLAG (N-terminal) and c-myc (C-terminal) epitopes.
Lipids and Liposomes.
In certain embodiments the effectors comprise one or more microparticles or nanoparticles that can be loaded with an effector agent (e.g., a pharmaceutical, a label, etc.). In certain embodiments the microparticles or nanoparticles are lipidic particles. Lipidic particles are microparticles or nanoparticles that include at least one lipid component forming a condensed lipid phase. Typically, a lipidic nanoparticle has preponderance of lipids in its composition. Various condensed lipid phases include solid amorphous or true crystalline phases; isomorphic liquid phases (droplets); and various hydrated mesomorphic oriented lipid phases such as liquid crystalline and pseudocrystalline bilayer phases (L-alpha, L-beta, P-beta, Lc), interdigitated bilayer phases, and nonlamellar phases (see, e.g., The Structure of Biological Membranes, ed. by P. Yeagle, CRC Press, Bora Raton, Fla., 1991). Lipidic microparticles include, but are not limited to a liposome, a lipid-nucleic acid complex, a lipid-drug complex, a lipid-label complex, a solid lipid particle, a microemulsion droplet, and the like. Methods of making and using these types of lipidic microparticles and nanoparticles, as well as attachment of affinity moieties, e.g., antibodies, to them are known in the art (see, e.g., U.S. Pat. Nos. 5,077,057; 5,100,591; 5,616,334; 6,406,713; 5,576,016; 6,248,363; Bondi et al. (2003) Drug Delivery 10: 245-250; Pedersen et al., (2006) Eur. J. Pharm. Biopharm. 62: 155-162, 2006 (solid lipid particles); U.S. Pat. Nos. 5,534,502; 6,720,001; Shiokawa et al. (2005) Clin. Cancer Res. 11: 2018-2025 (microemulsions); U.S. Pat. No. 6,071,533 (lipid-nucleic acid complexes), and the like).
A liposome is generally defined as a particle comprising one or more lipid bilayers enclosing an interior, typically an aqueous interior. Thus, a liposome is often a vesicle formed by a bilayer lipid membrane. There are many methods for the preparation of liposomes. Some of them are used to prepare small vesicles (d<0.05 micrometer), some for larger vesicles (d>0.05 micrometer). Some are used to prepare multilamellar vesicles, some for unilamellar ones. Methods for liposome preparation are exhaustively described in several review articles such as Szoka and Papahadjopoulos (1980) Ann. Rev. Biophys. Bioeng., 9: 467, Deamer and Uster (1983) Pp. 27-51 In: Liposomes, ed. M. J. Ostro, Marcel Dekker, New York, and the like.
In various embodiments the liposomes include a surface coating of a hydrophilic polymer chain. “Surface-coating” refers to the coating of any hydrophilic polymer on the surface of liposomes. The hydrophilic polymer is included in the liposome by including in the liposome composition one or more vesicle-forming lipids derivatized with a hydrophilic polymer chain. In certain embodiments, vesicle-forming lipids with diacyl chains, such as phospholipids, are preferred. One illustrative phospholipid is phosphatidylethanolamine (PE), which contains a reactive amino group convenient for coupling to the activated polymers. One illustrative PE is distearoyl PE (DSPE). Another example is non-phospholipid double chain amphiphilic lipids, such as diacyl- or dialkylglycerols, derivatized with a hydrophilic polymer chain.
In certain embodiments a hydrophilic polymer for use in coupling to a vesicle forming lipid is polyethyleneglycol (PEG), preferably as a PEG chain having a molecular weight between 1,000-10,000 Daltons, more preferably between 1,000-5,000 Daltons, most preferably between 2,000-5,000 Daltons. Methoxy or ethoxy-capped analogues of PEG are also useful hydrophilic polymers, commercially available in a variety of polymer sizes, e.g., 120-20,000 Daltons.
Other hydrophilic polymers that can be suitable include, but are not limited to polylactic acid, polyglycolic acid, polyvinylpyrrolidone, polymethyloxazoline, polyethyloxazoline, polyhydroxypropyl methacrylamide, polymethacrylamide, polydimethylacrylamide, and derivatized celluloses, such as hydroxymethylcellulose or hydroxyethylcellulose.
Preparation of lipid-polymer conjugates containing these polymers attached to a suitable lipid, such as PE, have been described, for example in U.S. Pat. No. 5,395,
The liposomes can, optionally be prepared for attachment to one or more targeting moieties described herein. Here the lipid component included in the liposomes would include either a lipid derivatized with the targeting moiety, or a lipid having a polar-head chemical group, e.g., on a linker, that can be derivatized with the targeting moiety in preformed liposomes, according to known methods.
Methods of functionalizing lipids and liposomes with affinity moieties such as antibodies are well known to those of skill in the art (see, e.g., DE 3,218,121; Epstein et al. (1985) Proc. Natl. Acad. Sci., USA, 82:3688 (1985); Hwang et al. (1980) Proc. Natl. Acad. Sci., USA, 77: 4030; EP 52,322; EP 36,676; EP 88,046; EP 143,949; EP 142,641; Japanese patent application 83-118008; U.S. Pat. Nos. 4,485,045 and 4,544,545; and EP 102,324, all of which are incorporated herein by reference).
Polymeric Microparticles and/or Nanoparticles.
In certain embodiments the effector(s) comprise polymeric microparticles and/or nanoparticles and/or micelles.
Microparticle and nanoparticle-based drug delivery systems have considerable potential for treatment of various microorganisms. Technological advantages of polymeric microparticles or nanoparticles used as drug carriers are high stability, high carrier capacity, feasibility of incorporation of both hydrophilic and hydrophobic substances, and feasibility of variable routes of administration, including oral application and inhalation. Polymeric nanoparticles can also be designed to allow controlled (sustained) drug release from the matrix. These properties of nanoparticles enable improvement of drug bioavailability and reduction of the dosing frequency.
Polymeric nanoparticles are typically micron or submicron (<1 μm) colloidal particles. This definition includes monolithic nanoparticles (nanospheres) in which the drug is adsorbed, dissolved, or dispersed throughout the matrix and nanocapsules in which the drug is confined to an aqueous or oily core surrounded by a shell-like wall. Alternatively, in certain embodiments, the drug can be covalently attached to the surface or into the matrix.
Polymeric microparticles and nanoparticles are typically made from biocompatible and biodegradable materials such as polymers, either natural (e.g., gelatin, albumin) or synthetic (e.g., polylactides, polyalkylcyanoacrylates), or solid lipids. In the body, the drug loaded in nanoparticles is usually released from the matrix by diffusion, swelling, erosion, or degradation. One commonly used material is poly(lactide-co-glycolide) (PLG).
Methods of fabricating and loading polymeric nanoparticles or microparticles are well known to those of skill in the art. Thus, for example, Matsumoto et al. (1999) Intl. J. Pharmaceutics, 185: 93-101 teaches the fabrication of poly(L-lactide)-poly(ethylene glycol)-poly(L-lactide) nanoparticles, Chawla et al. (2002) Intl. J. Pharmaceutics 249: 127-138, teaches the fabrication and use of poly(ε-caprolactone) nanoparticles delivery of tamifoxen, and Bodmeier et al. (1988) Intl. J. Pharmaceutics, 43: 179-186, teaches the preparation of poly(D,L-lactide) microspheres using a solvent evaporation method. ° “Intl. J. Pharmaceutics, 1988, 43, 179-186. Other nanoparticle formulations are described, for example, by Williams et al. (2003) J. Controlled Release, 91: 167-172; Leroux et al. (1996) J. Controlled Release, 39: 339-350; Soppimath et al. (2001) J. Controlled Release, 70:1-20; Brannon-Peppas (1995) Intl. J. Pharmaceutics, 116: 1-9; and the like.
Peptide Preparation.
The peptides described herein can be chemically synthesized using standard chemical peptide synthesis techniques or, particularly where the peptide does not comprise “D” amino acid residues, the peptide can be recombinantly expressed. Where the “D” polypeptides are recombinantly expressed, a host organism (e.g. bacteria, plant, fungal cells, etc.) can be cultured in an environment where one or more of the amino acids is provided to the organism exclusively in a D form. Recombinantly expressed peptides in such a system then incorporate those D amino acids.
In certain embodiments, D amino acids can be incorporated in recombinantly expressed peptides using modified amino acyl-tRNA synthetases that recognize D-amino acids.
In certain embodiments the peptides are chemically synthesized by any of a number of fluid or solid phase peptide synthesis techniques known to those of skill in the art. Solid phase synthesis in which the C-terminal amino acid of the sequence is attached to an insoluble support followed by sequential addition of the remaining amino acids in the sequence is a preferred method for the chemical synthesis of the polypeptides of this invention. Techniques for solid phase synthesis are well known to those of skill in the art and are described, for example, by Barany and Merrifield (1963) Solid-Phase Peptide Synthesis; pp. 3-284 in The Peptides: Analysis, Synthesis, Biology. Vol. 2: Special Methods in Peptide Synthesis, Part A.; Merrifield et al. (1963) J. Am. Chem. Soc., 85: 2149-2156, and Stewart et al. (1984) Solid Phase Peptide Synthesis, 2nd ed. Pierce Chem. Co., Rockford, Ill.
In one embodiment, the peptides can be synthesized by the solid phase peptide synthesis procedure using a benzhyderylamine resin (Beckman Bioproducts, 0.59 mmol of NH2/g of resin) as the solid support. The COOH terminal amino acid (e.g., t-butylcarbonyl-Phe) is attached to the solid support through a 4-(oxymethyl)phenacetyl group. This is a more stable linkage than the conventional benzyl ester linkage, yet the finished peptide can still be cleaved by hydrogenation. Transfer hydrogenation using formic acid as the hydrogen donor can be used for this purpose.
It is noted that in the chemical synthesis of peptides, particularly peptides comprising D amino acids, the synthesis usually produces a number of truncated peptides in addition to the desired full-length product. Thus, the peptides are typically purified using, e.g., HPLC.
D-amino acids, beta amino acids, non-natural amino acids, and the like can be incorporated at one or more positions in the peptide simply by using the appropriately derivatized amino acid residue in the chemical synthesis. Modified residues for solid phase peptide synthesis are commercially available from a number of suppliers (see, e.g., Advanced Chem Tech, Louisville; Nova Biochem, San Diego; Sigma, St Louis; Bachem California Inc., Torrance, etc.). The D-form and/or otherwise modified amino acids can be completely omitted or incorporated at any position in the peptide as desired. Thus, for example, in certain embodiments, the peptide can comprise a single modified acid, while in other embodiments, the peptide comprises at least two, generally at least three, more generally at least four, most generally at least five, preferably at least six, more preferably at least seven or even all modified amino acids. In certain embodiments, essentially every amino acid is a D-form amino acid.
As indicated above, the peptides and/or fusion proteins of this invention can also be recombinantly expressed. Accordingly, in certain embodiments, the antimicrobial peptides and/or targeting moieties, and/or fusion proteins of this invention are synthesized using recombinant expression systems. Generally this involves creating a DNA sequence that encodes the desired peptide or fusion protein, placing the DNA in an expression cassette under the control of a particular promoter, expressing the peptide or fusion protein in a host, isolating the expressed peptide or fusion protein and, if required, renaturing the peptide or fusion protein.
DNA encoding the peptide(s) or fusion protein(s) described herein can be prepared by any suitable method as described above, including, for example, cloning and restriction of appropriate sequences or direct chemical synthesis.
This nucleic acid can be easily ligated into an appropriate vector containing appropriate expression control sequences (e.g. promoter, enhancer, etc.), and, optionally, containing one or more selectable markers (e.g. antibiotic resistance genes).
The nucleic acid sequences encoding the peptides or fusion proteins described herein can be expressed in a variety of host cells, including, but not limited to, E. coli, other bacterial hosts, yeast, fungus, and various higher eukaryotic cells such as insect cells (e.g. SF3), the COS, CHO and HeLa cells lines and myeloma cell lines. The recombinant protein gene will typically be operably linked to appropriate expression control sequences for each host. For E. coli this can include a promoter such as the T7, trp, or lambda promoters, a ribosome binding site and preferably a transcription termination signal. For eukaryotic cells, the control sequences can include a promoter and often an enhancer (e.g., an enhancer derived from immunoglobulin genes, SV40, cytomegalovirus, etc.), and a polyadenylation sequence, and may include splice donor and acceptor sequences.
The plasmids can be transferred into the chosen host cell by well-known methods such as calcium chloride transformation for E. coli and calcium phosphate treatment or electroporation for mammalian cells. Cells transformed by the plasmids can be selected by resistance to antibiotics conferred by genes contained on the plasmids, such as the amp, gpt, neo and hyg genes.
Once expressed, the recombinant peptide(s) or fusion protein(s) can be purified according to standard procedures of the art, including ammonium sulfate precipitation, affinity columns, column chromatography, gel electrophoresis and the like (see, generally, R. Scopes, (1982) Protein Purification, Springer-Verlag, N.Y.; Deutscher (1990) Methods in Enzymology Vol. 182: Guide to Protein Purification., Academic Press, Inc. N.Y.). Substantially pure compositions of at least about 90 to 95% homogeneity are preferred, and 98 to 99% or more homogeneity are most preferred.
One of skill in the art would recognize that after chemical synthesis, biological expression, or purification, the peptide(s) or fusion protein(s) may possess a conformation substantially different than desired native conformation. In this case, it may be necessary to denature and reduce the peptide or fusion protein and then to cause the molecule to re-fold into the preferred conformation. Methods of reducing and denaturing proteins and inducing re-folding are well known to those of skill in the art (see, e.g., Debinski et al. (1993) J. Biol. Chem., 268: 14065-14070; Kreitman and Pastan (1993) Bioconjug. Chem., 4: 581-585; and Buchner, et al., (1992) Anal. Biochem., 205: 263-270). Debinski et al., for example, describes the denaturation and reduction of inclusion body proteins in guanidine-DTE. The protein is then refolded in a redox buffer containing oxidized glutathione and L-arginine.
One of skill would recognize that modifications can be made to the peptide(s) and/or fusion protein(s) proteins without diminishing their biological activity. Some modifications may be made to facilitate the cloning, expression, or incorporation of the targeting molecule into a fusion protein. Such modifications are well known to those of skill in the art and include, for example, a methionine added at the amino terminus to provide an initiation site, or additional amino acids (e.g., poly His) placed on either terminus to create conveniently located restriction sites or termination codons or purification sequences.
Protecting Groups.
While the various peptides (e.g., targeting peptides, antimicrobial peptides, STAMPs) described herein may be shown with no protecting groups, in certain embodiments they can bear one, two, three, four, or more protecting groups. In various embodiments, the protecting groups can be coupled to the C- and/or N-terminus of the peptide(s) and/or to one or more internal residues comprising the peptide(s) (e.g., one or more R-groups on the constituent amino acids can be blocked). Thus, for example, in certain embodiments, any of the peptides described herein can bear, e.g., an acetyl group protecting the amino terminus and/or an amide group protecting the carboxyl terminus. One example of such a protected peptide is the 1845L6-21 STAMP having the amino acid sequence KFINGVLSQFVLERKPYPKLFKFLRKHLL* (SEQ ID NO:1953), where the asterisk indicates an amidated carboxyl terminus. Of course, this protecting group can be can be eliminated and/or substituted with another protecting group as described herein.
Without being bound by a particular theory, it was discovered that addition of a protecting group, particularly to the carboxyl and in certain embodiments the amino terminus can improve the stability and efficacy of the peptide.
A wide number of protecting groups are suitable for this purpose. Such groups include, but are not limited to acetyl, amide, and alkyl groups with acetyl and alkyl groups being particularly preferred for N-terminal protection and amide groups being preferred for carboxyl terminal protection. In certain particularly preferred embodiments, the protecting groups include, but are not limited to alkyl chains as in fatty acids, propionyl, formyl, and others. Particularly preferred carboxyl protecting groups include amides, esters, and ether-forming protecting groups. In one preferred embodiment, an acetyl group is used to protect the amino terminus and an amide group is used to protect the carboxyl terminus. These blocking groups enhance the helix-forming tendencies of the peptides. Certain particularly preferred blocking groups include alkyl groups of various lengths, e.g., groups having the formula: CH3—(CH2)n—CO— where n ranges from about 1 to about 20, preferably from about 1 to about 16 or 18, more preferably from about 3 to about 13, and most preferably from about 3 to about 10.
In certain embodiments, the protecting groups include, but are not limited to alkyl chains as in fatty acids, propionyl, formyl, and others. Particularly preferred carboxyl protecting groups include amides, esters, and ether-forming protecting groups. In one embodiment, an acetyl group is used to protect the amino terminus and/or an amino group is used to protect the carboxyl terminus (i.e., amidated carboxyl terminus). In certain embodiments blocking groups include alkyl groups of various lengths, e.g., groups having the formula: CH3—(CH2)n—CO— where n ranges from about 3 to about 20, preferably from about 3 to about 16, more preferably from about 3 to about 13, and most preferably from about 3 to about 10.
In certain embodiments, the acid group on the C-terminal can be blocked with an alcohol, aldehyde or ketone group and/or the N-terminal residue can have the natural amide group, or be blocked with an acyl, carboxylic acid, alcohol, aldehyde, or ketone group.
Other protecting groups include, but are not limited to Fmoc, t-butoxycarbonyl (t-BOC), 9-fluoreneacetyl group, 1-fluorenecarboxylic group, 9-florenecarboxylic group, 9-fluorenone-1-carboxylic group, benzyloxycarbonyl, xanthyl (Xan), trityl (Trt), 4-methyltrityl (Mtt), 4-methoxytrityl (Mmt), 4-methoxy-2,3,6-trimethyl-benzenesulphonyl (Mtr), Mesitylene-2-sulphonyl (Mts), 4,4-dimethoxybenzhydryl (Mbh), Tosyl (Tos), 2,2,5,7,8-pentamethyl chroman-6-sulphonyl (Pmc), 4-methylbenzyl (MeBzl), 4-methoxybenzyl (MeOBzl), benzyloxy (BzlO), benzyl (Bzl), benzoyl (Bz), 3-nitro-2-pyridinesulphenyl (Npys), 1-(4,4-dimentyl-2,6-diaxocyclohexylidene)ethyl (Dde), 2,6-dichlorobenzyl (2,6-DiCl-Bzl), 2-chlorobenzyloxycarbonyl (2-Cl-Z), 2-bromobenzyloxycarbonyl (2-Br-Z), Benzyloxymethyl (Bom), cyclohexyloxy (cHxO), t-butoxymethyl (Bum), t-butoxy (tBuO), t-Butyl (tBu), Acetyl (Ac), and Trifluoroacetyl (TFA).
Protecting/blocking groups are well known to those of skill as are methods of coupling such groups to the appropriate residue(s) comprising the peptides of this invention (see, e.g., Greene et al., (1991) Protective Groups in Organic Synthesis, 2nd ed., John Wiley & Sons, Inc., Somerset, N.J.). In an illustrative embodiment, for example, acetylation is accomplished during the synthesis when the peptide is on the resin using acetic anhydride. Amide protection can be achieved by the selection of a proper resin for the synthesis. For example, a rink amide resin can be used. After the completion of the synthesis, the semipermanent protecting groups on acidic bifunctional amino acids such as Asp and Glu and basic amino acid Lys, hydroxyl of Tyr are all simultaneously removed. The peptides released from such a resin using acidic treatment comes out with the n-terminal protected as acetyl and the carboxyl protected as NH2 and with the simultaneous removal of all of the other protecting groups.
While amino acid sequences are disclosed herein, amino acid sequences comprising, one or more protecting groups, e.g., as described above (or any other commercially available protecting groups for amino acids used, e.g., in boc or fmoc peptide synthesis) are also contemplated.
Peptide Circularization.
In certain embodiments the peptides described herein (e.g., AMPs, compound AMPs, STAMPs, etc.) are circularized/cyclized to produce cyclic peptides. Cyclic peptides, as contemplated herein, include head/tail, head/side chain, tail/side chain, and side chain/side chain cyclized peptides. In addition, peptides contemplated herein include homodet, containing only peptide bonds, and heterodet containing in addition disulfide, ester, thioester-bonds, or other bonds.
The cyclic peptides can be prepared using virtually any art-known technique for the preparation of cyclic peptides. For example, the peptides can be prepared in linear or non-cyclized form using conventional solution or solid phase peptide syntheses and cyclized using standard chemistries. Preferably, the chemistry used to cyclize the peptide will be sufficiently mild so as to avoid substantially degrading the peptide. Suitable procedures for synthesizing the peptides described herein as well as suitable chemistries for cyclizing the peptides are well known in the art.
In various embodiments cyclization can be achieved via direct coupling of the N- and C-terminus to form a peptide (or other) bond, but can also occur via the amino acid side chains. Furthermore it can be based on the use of other functional groups, including but not limited to amino, hydroxy, sulfhydryl, halogen, sulfonyl, carboxy, and thiocarboxy. These groups can be located at the amino acid side chains or be attached to their N- or C-terminus.
Accordingly, it is to be understood that the chemical linkage used to covalently cyclize the peptides of the invention need not be an amide linkage. In many instances it may be desirable to modify the N- and C-termini of the linear or non-cyclized peptide so as to provide, for example, reactive groups that may be cyclized under mild reaction conditions. Such linkages include, by way of example and not limitation amide, ester, thioester, CH2—NH, etc. Techniques and reagents for synthesizing peptides having modified termini and chemistries suitable for cyclizing such modified peptides are well-known in the art.
Alternatively, in instances where the ends of the peptide are conformationally or otherwise constrained so as to make cyclization difficult, it may be desirable to attach linkers to the N- and/or C-termini to facilitate peptide cyclization. Of course, it will be appreciated that such linkers will bear reactive groups capable of forming covalent bonds with the termini of the peptide. Suitable linkers and chemistries are well-known in the art and include those previously described.
Cyclic peptides and depsipeptides (heterodetic peptides that include ester (depside) bonds as part of their backbone) have been well characterized and show a wide spectrum of biological activity. The reduction in conformational freedom brought about by cyclization often results in higher receptor-binding affinities. Frequently in these cyclic compounds, extra conformational restrictions are also built in, such as the use of D- and N-alkylated-amino acids, α,β-dehydro amino acids or α,α-disubstituted amino acid residues.
Methods of forming disulfide linkages in peptides are well known to those of skill in the art (see, e.g., Eichler and Houghten (1997) Protein Pept. Lett. 4: 157-164).
Reference may also be made to Marlowe (1993) Biorg. Med. Chem. Lett. 3: 437-44 who describes peptide cyclization on TFA resin using trimethylsilyl (TMSE) ester as an orthogonal protecting group; Pallin and Tam (1995) J. Chem. Soc. Chem. Comm. 2021-2022) who describe the cyclization of unprotected peptides in aqueous solution by oxime formation; Algin et al. (1994) Tetrahedron Lett. 35: 9633-9636 who disclose solid-phase synthesis of head-to-tail cyclic peptides via lysine side-chain anchoring; Kates et al. (1993) Tetrahedron Lett. 34: 1549-1552 who describe the production of head-to-tail cyclic peptides by three-dimensional solid phase strategy; Tumelty et al. (1994) J. Chem. Soc. Chem. Comm. 1067-1068, who describe the synthesis of cyclic peptides from an immobilized activated intermediate, where activation of the immobilized peptide is carried out with N-protecting group intact and subsequent removal leading to cyclization; McMurray et al. (1994) Peptide Res. 7: 195-206) who disclose head-to-tail cyclization of peptides attached to insoluble supports by means of the side chains of aspartic and glutamic acid; Hruby et al. (1994) Reactive Polymers 22: 231-241) who teach an alternate method for cyclizing peptides via solid supports; and Schmidt and Langer (1997) J. Peptide Res. 49: 67-73, who disclose a method for synthesizing cyclotetrapeptides and cyclopentapeptides.
These methods of peptide cyclization are illustrative and non-limiting. Using the teaching provide herein, other cyclization methods will be available to one of skill in the art.
Joining Targeting Moieties to Effectors.
Chemical Conjugation.
Chimeric moieties are formed by joining one or more of the targeting moieties described herein to one or more effectors. In certain embodiments the targeting moieties are attached directly to the effector(s) via naturally occurring reactive groups or the targeting moiety and/or the effector(s) can be functionalized to provide such reactive groups.
In various embodiments the targeting moieties are attached to effector(s) via one or more linking agents. Thus, in various embodiments the targeting moieties and the effector(s) can be conjugated via a single linking agent or multiple linking agents. For example, the targeting moiety and the effector can be conjugated via a single multifunctional (e.g., bi-, tri-, or tetra-) linking agent or a pair of complementary linking agents. In another embodiment, the targeting moiety and the effector are conjugated via two, three, or more linking agents. Suitable linking agents include, but are not limited to, e.g., functional groups, affinity agents, stabilizing groups, and combinations thereof.
In certain embodiments the linking agent is or comprises a functional group. Functional groups include monofunctional linkers comprising a reactive group as well as multifunctional crosslinkers comprising two or more reactive groups capable of forming a bond with two or more different functional targets (e.g., labels, proteins, macromolecules, semiconductor nanocrystals, or substrate). In some preferred embodiments, the multifunctional crosslinkers are heterobifunctional crosslinkers comprising two or more different reactive groups.
Suitable reactive groups include, but are not limited to thiol (—SH), carboxylate (COOH), carboxyl (—COOH), carbonyl, amine (NH2), hydroxyl (—OH), aldehyde (—CHO), alcohol (ROH), ketone (R2CO), active hydrogen, ester, sulfhydryl (SH), phosphate (—PO3), or photoreactive moieties. Amine reactive groups include, but are not limited to e.g., isothiocyanates, isocyanates, acyl azides, NHS esters, sulfonyl chlorides, aldehydes and glyoxals, epoxides and oxiranes, carbonates, arylating agents, imidoesters, carbodiimides, and anhydrides. Thiol-reactive groups include, but are not limited to e.g., haloacetyl and alkyl halide derivates, maleimides, aziridines, acryloyl derivatives, arylating agents, and thiol-disulfides exchange reagents. Carboxylate reactive groups include, but are not limited to e.g., diazoalkanes and diazoacetyl compounds, such as carbonyldiimidazoles and carbodiimides. Hydroxyl reactive groups include, but are not limited to e.g., epoxides and oxiranes, carbonyldiimidazole, oxidation with periodate, N,N′-disuccinimidyl carbonate or N-hydroxylsuccimidyl chloroformate, enzymatic oxidation, alkyl halogens, and isocyanates. Aldehyde and ketone reactive groups include, but are not limited to e.g., hydrazine derivatives for schiff base formation or reduction amination. Active hydrogen reactive groups include, but are not limited to e.g., diazonium derivatives for mannich condensation and iodination reactions. Photoreactive groups include, but are not limited to e.g., aryl azides and halogenated aryl azides, benzophenones, diazo compounds, and diazirine derivatives.
Other suitable reactive groups and classes of reactions useful in forming chimeric moieties include those that are well known in the art of bioconjugate chemistry. Currently favored classes of reactions available with reactive chelates are those which proceed under relatively mild conditions. These include, but are not limited to, nucleophilic substitutions (e.g., reactions of amines and alcohols with acyl halides, active esters), electrophilic substitutions (e.g., enamine reactions), and additions to carbon-carbon and carbon-heteroatom multiple bonds (e.g., Michael reaction, Diels-Alder addition). These and other useful reactions are discussed in, for example, March (1985) Advanced Organic Chemistry, 3rd Ed., John Wiley & Sons, New York, Hermanson (1996) Bioconjugate Techniques, Academic Press, San Diego; and Feeney et al. (1982) Modification of Proteins; Advances in Chemistry Series, Vol. 198, American Chemical Society, Washington, D.C.
In certain embodiments, the linking agent comprises a chelator. For example, the chelator comprising the molecule, DOTA (DOTA=1,4,7,10-tetrakis(carboxymethyl)-1,4,7,10-tetraazacyclododecane), can readily be labeled with a radiolabel, such as Gd3+ and 64Cu, resulting in Gd3+-DOTA and 64Cu-DOTA respectively, attached to the targeting moiety. Other suitable chelates are known to those of skill in the art, for example, 1,4,7-triazacyclononane-N,N′,N″-triacetic acid (NOTA) derivatives being among the most well known (see, e.g., Lee et al. (1997) Nucl Med. Biol. 24: 2225-23019).
A “linker” or “linking agent” as used herein, is a molecule that is used to join two or more molecules. In certain embodiments the linker is typically capable of forming covalent bonds to both molecule(s) (e.g., the targeting moiety and the effector). Suitable linkers are well known to those of skill in the art and include, but are not limited to, straight or branched-chain carbon linkers, heterocyclic carbon linkers, or peptide linkers. In certain embodiments the linkers can be joined to the constituent amino acids through their side groups (e.g., through a disulfide linkage to cysteine). However, in certain embodiments, the linkers will be joined to the alpha carbon amino and carboxyl groups of the terminal amino acids.
A bifunctional linker having one functional group reactive with a group on one molecule (e.g., a targeting peptide), and another group reactive on the other molecule (e.g., an antimicrobial peptide), can be used to form the desired conjugate. Alternatively, derivatization can be performed to provide functional groups. Thus, for example, procedures for the generation of free sulfhydryl groups on peptides are also known (See U.S. Pat. No. 4,659,839).
In certain embodiments the linking agent is a heterobifunctional crosslinker comprising two or more different reactive groups that form a heterocyclic ring that can interact with a peptide. For example, a heterobifunctional crosslinker such as cysteine may comprise an amine reactive group and a thiol-reactive group can interact with an aldehyde on a derivatized peptide. Additional combinations of reactive groups suitable for heterobifunctional crosslinkers include, for example, amine- and sulfhydryl reactive groups; carbonyl and sulfhydryl reactive groups; amine and photoreactive groups; sulfhydryl and photoreactive groups; carbonyl and photoreactive groups; carboxylate and photoreactive groups; and arginine and photoreactive groups. In one embodiment, the heterobifunctional crosslinker is SMCC.
Many procedures and linker molecules for attachment of various molecules to peptides or proteins are known (see, e.g., European Patent Application No. 188,256; U.S. Pat. Nos. 4,671,958, 4,659,839, 4,414,148, 4,699,784; 4,680,338; 4,569,789; and 4,589,071; and Borlinghaus et al. (1987) Cancer Res. 47: 4071-4075). Illustrative linking protocols are provided herein in Examples 2 and 3.
Fusion Proteins.
In certain embodiments where the targeting moiety and effector are both peptides or both comprise peptides, the chimeric moiety can be chemically synthesized or recombinantly expressed as a fusion protein (i.e., a chimeric fusion protein).
In certain embodiments the chimeric fusion proteins are synthesized using recombinant DNA methodology. Generally this involves creating a DNA sequence that encodes the fusion protein, placing the DNA in an expression cassette under the control of a particular promoter, expressing the protein in a host, isolating the expressed protein and, if required, renaturing the protein.
DNA encoding the fusion proteins can be prepared by any suitable method, including, for example, cloning and restriction of appropriate sequences or direct chemical synthesis by methods such as the phosphotriester method of Narang et al. (1979) Meth. Enzymol. 68: 90-99; the phosphodiester method of Brown et al. (1979) Meth. Enzymol. 68: 109-151; the diethylphosphoramidite method of Beaucage et al. (1981) Tetra. Lett., 22: 1859-1862; and the solid support method of U.S. Pat. No. 4,458,066.
Chemical synthesis produces a single stranded oligonucleotide. This can be converted into double stranded DNA by hybridization with a complementary sequence or by polymerization with a DNA polymerase using the single strand as a template. One of skill would recognize that while chemical synthesis of DNA is limited to sequences of about 100 bases, longer sequences can be obtained by the ligation of shorter sequences.
Alternatively, subsequences can be cloned and the appropriate subsequences cleaved using appropriate restriction enzymes. The fragments can then be ligated to produce the desired DNA sequence.
In certain embodiments, DNA encoding fusion proteins of the present invention may be cloned using DNA amplification methods such as polymerase chain reaction (PCR). Thus, for example, the nucleic acid encoding a targeting antibody, a targeting peptide, and the like is PCR amplified, using a sense primer containing the restriction site for NdeI and an antisense primer containing the restriction site for HindIII. This produces a nucleic acid encoding the targeting sequence and having terminal restriction sites. Similarly an effector and/or effector/linker/spacer can be provided having complementary restriction sites. Ligation of sequences and insertion into a vector produces a vector encoding the fusion protein.
While the targeting moieties and effector(s) can be directly joined together, one of skill will appreciate that they can be separated by a peptide spacer/linker consisting of one or more amino acids. Generally the spacer will have no specific biological activity other than to join the proteins or to preserve some minimum distance or other spatial relationship between them. However, the constituent amino acids of the spacer may be selected to influence some property of the molecule such as the folding, net charge, or hydrophobicity.
The nucleic acid sequences encoding the fusion proteins can be expressed in a variety of host cells, including E. coli, other bacterial hosts, yeast, and various higher eukaryotic cells such as the COS, CHO and HeLa cells lines and myeloma cell lines. The recombinant protein gene will be operably linked to appropriate expression control sequences for each host. For E. coli this includes a promoter such as the T7, trp, or lambda promoters, a ribosome binding site and preferably a transcription termination signal. For eukaryotic cells, the control sequences will include a promoter and preferably an enhancer derived from immunoglobulin genes, SV40, cytomegalovirus, etc., and a polyadenylation sequence, and may include splice donor and acceptor sequences.
The plasmids can be transferred into the chosen host cell by well-known methods such as calcium chloride transformation for E. coli and calcium phosphate treatment or electroporation for mammalian cells. Cells transformed by the plasmids can be selected by resistance to antibiotics conferred by genes contained on the plasmids, such as the amp, gpt, neo and hyg genes.
Once expressed, the recombinant fusion proteins can be purified according to standard procedures of the art, including ammonium sulfate precipitation, affinity columns, column chromatography, gel electrophoresis and the like (see, generally, R. Scopes (1982) Protein Purification, Springer-Verlag, N.Y.; Deutscher (1990) Methods in Enzymology Vol. 182: Guide to Protein Purification., Academic Press, Inc. N.Y.). Substantially pure compositions of at least about 90 to 95% homogeneity are preferred, and 98 to 99% or more homogeneity are most preferred for pharmaceutical uses. Once purified, partially or to homogeneity as desired, the polypeptides may then be used therapeutically.
One of skill in the art would recognize that after chemical synthesis, biological expression, or purification, the fusion protein may possess a conformation substantially different than the native conformations of the constituent polypeptides. In this case, it may be necessary to denature and reduce the polypeptide and then to cause the polypeptide to re-fold into the preferred conformation. Methods of reducing and denaturing proteins and inducing re-folding are well known to those of skill in the art (See, Debinski et al. (1993) J. Biol. Chem., 268: 14065-14070; Kreitman and Pastan (1993) Bioconjug. Chem., 4: 581-585; and Buchner, et al. (1992) Anal. Biochem., 205: 263-270).
One of skill would recognize that modifications can be made to the fusion proteins without diminishing their biological activity. Some modifications may be made to facilitate the cloning, expression, or incorporation of the targeting molecule into a fusion protein. Such modifications are well known to those of skill in the art and include, for example, a methionine added at the amino terminus to provide an initiation site, or additional amino acids placed on either terminus to create conveniently located restriction sites or termination codons.
As indicated above, in various embodiments a peptide linker/spacer is used to join the one or more targeting moieties to one or more effector(s). In various embodiments the peptide linker is relatively short, typically less than about 10 amino acids, preferably less than about 8 amino acids and more preferably about 3 to about 5 amino acids. Suitable illustrative linkers include, but are not limited to PSGSP ((SEQ ID NO:1932), ASASA (SEQ ID NO: 1933), or GGG (SEQ ID NO: 1934). In certain embodiments longer linkers such as (GGGGS)3 (SEQ ID NO:1935) can be used. Illustrative peptide linkers and other linkers are shown in Table 11.
Multiple Targeting Moieties and/or Effectors.
As indicated above, in certain embodiments, the chimeric moieties described herein comprise multiple targeting moieties attached to a single effector or multiple effectors attached to a single targeting moiety, or multiple targeting moieties attached to multiple effectors.
Where the chimeric construct is a fusion protein this is easily accomplished by providing multiple domains that are targeting domains attached to one or more effector domains.
When the chimeric construct is a chemical conjugate linear or branched configurations (e.g., as illustrated in
Pharmaceutical Formulations.
In certain embodiments, the antimicrobial peptides and/or the chimeric constructs (e.g., targeting moieties attached to antimicrobial peptide(s), targeting moieties attached to detectable label(s), etc.) are administered to a mammal in need thereof, to a cell, to a tissue, to a composition (e.g., a food, etc.). In various embodiments the compositions can be administered to detect and/or locate, and/or quantify the presence of particular microorganisms, microorganism populations, biofilms comprising particular microorganisms, and the like. In various embodiments the compositions can be administered to inhibit particular microorganisms, microorganism populations, biofilms comprising particular microorganisms, and the like.
These active agents (antimicrobial peptides and/or chimeric moieties) can be administered in the “native” form or, if desired, in the form of salts, esters, amides, prodrugs, derivatives, and the like, provided the salt, ester, amide, prodrug or derivative is suitable pharmacologically, i.e., effective in the present method(s). Salts, esters, amides, prodrugs and other derivatives of the active agents can be prepared using standard procedures known to those skilled in the art of synthetic organic chemistry and described, for example, by March (1992) Advanced Organic Chemistry; Reactions, Mechanisms and Structure, 4th Ed. N.Y. Wiley-Interscience.
Methods of formulating such derivatives are known to those of skill in the art. For example, the disulfide salts of a number of delivery agents are described in PCT Publication WO 00/059863 which is incorporated herein by reference. Similarly, acid salts of therapeutic peptides, peptoids, or other mimetics, and can be prepared from the free base using conventional methodology that typically involves reaction with a suitable acid. Generally, the base form of the drug is dissolved in a polar organic solvent such as methanol or ethanol and the acid is added thereto. The resulting salt either precipitates or can be brought out of solution by addition of a less polar solvent. Suitable acids for preparing acid addition salts include, but are not limited to both organic acids, e.g., acetic acid, propionic acid, glycolic acid, pyruvic acid, oxalic acid, malic acid, malonic acid, succinic acid, maleic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, salicylic acid, and the like, as well as inorganic acids, e.g., hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and the like. An acid addition salt can be reconverted to the free base by treatment with a suitable base. Certain particularly preferred acid addition salts of the active agents herein include halide salts, such as may be prepared using hydrochloric or hydrobromic acids. Conversely, preparation of basic salts of the active agents of this invention are prepared in a similar manner using a pharmaceutically acceptable base such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, calcium hydroxide, trimethylamine, or the like. In certain embodiments basic salts include alkali metal salts, e.g., the sodium salt, and copper salts.
For the preparation of salt forms of basic drugs, the pKa of the counterion is preferably at least about 2 pH lower than the pKa of the drug. Similarly, for the preparation of salt forms of acidic drugs, the pKa of the counterion is preferably at least about 2 pH higher than the pKa of the drug. This permits the counterion to bring the solution's pH to a level lower than the pHmax to reach the salt plateau, at which the solubility of salt prevails over the solubility of free acid or base. The generalized rule of difference in pKa units of the ionizable group in the active pharmaceutical ingredient (API) and in the acid or base is meant to make the proton transfer energetically favorable. When the pKa of the API and counterion are not significantly different, a solid complex may form but may rapidly disproportionate (i.e., break down into the individual entities of drug and counterion) in an aqueous environment.
Preferably, the counterion is a pharmaceutically acceptable counterion. Suitable anionic salt forms include, but are not limited to acetate, benzoate, benzylate, bitartrate, bromide, carbonate, chloride, citrate, edetate, edisylate, estolate, fumarate, gluceptate, gluconate, hydrobromide, hydrochloride, iodide, lactate, lactobionate, malate, maleate, mandelate, mesylate, methyl bromide, methyl sulfate, mucate, napsylate, nitrate, pamoate (embonate), phosphate and diphosphate, salicylate and disalicylate, stearate, succinate, sulfate, tartrate, tosylate, triethiodide, valerate, and the like, while suitable cationic salt forms include, but are not limited to aluminum, benzathine, calcium, ethylene diamine, lysine, magnesium, meglumine, potassium, procaine, sodium, tromethamine, zinc, and the like.
In various embodiments preparation of esters typically involves functionalization of hydroxyl and/or carboxyl groups that are present within the molecular structure of the active agent. In certain embodiments, the esters are typically acyl-substituted derivatives of free alcohol groups, i.e., moieties that are derived from carboxylic acids of the formula RCOOH where R is alky, and preferably is lower alkyl. Esters can be reconverted to the free acids, if desired, by using conventional hydrogenolysis or hydrolysis procedures.
Amides can also be prepared using techniques known to those skilled in the art or described in the pertinent literature. For example, amides may be prepared from esters, using suitable amine reactants, or they may be prepared from an anhydride or an acid chloride by reaction with ammonia or a lower alkyl amine.
In various embodiments, the active agents identified herein are useful for parenteral, topical, oral, nasal (or otherwise inhaled), rectal, or local administration, such as by aerosol or transdermally, for detection and/or quantification, and or localization, and/or prophylactic and/or therapeutic treatment of infection (e.g., microbial infection). The compositions can be administered in a variety of unit dosage forms depending upon the method of administration. Suitable unit dosage forms, include, but are not limited to powders, tablets, pills, capsules, lozenges, suppositories, patches, nasal sprays, injectibles, implantable sustained-release formulations, lipid complexes, etc.
The active agents (e.g., antimicrobial peptides and/or chimeric constructs) described herein can also be combined with a pharmaceutically acceptable carrier (excipient) to form a pharmacological composition. Pharmaceutically acceptable carriers can contain one or more physiologically acceptable compound(s) that act, for example, to stabilize the composition or to increase or decrease the absorption of the active agent(s). Physiologically acceptable compounds can include, for example, carbohydrates, such as glucose, sucrose, or dextrans, antioxidants, such as ascorbic acid or glutathione, chelating agents, low molecular weight proteins, protection and uptake enhancers such as lipids, compositions that reduce the clearance or hydrolysis of the active agents, or excipients or other stabilizers and/or buffers.
Pharmaceutically acceptable carriers can contain one or more physiologically acceptable compound(s) that act, for example, to stabilize the composition or to increase or decrease the absorption of the active agent(s). Physiologically acceptable compounds can include, for example, carbohydrates, such as glucose, sucrose, or dextrans, antioxidants, such as ascorbic acid or glutathione, chelating agents, low molecular weight proteins, protection and uptake enhancers such as lipids, compositions that reduce the clearance or hydrolysis of the active agents, or excipients or other stabilizers and/or buffers.
Other physiologically acceptable compounds, particularly of use in the preparation of tablets, capsules, gel caps, and the like include, but are not limited to binders, diluent/fillers, disentegrants, lubricants, suspending agents, and the like.
In certain embodiments, to manufacture an oral dosage form (e.g., a tablet), an excipient (e.g., lactose, sucrose, starch, mannitol, etc.), an optional disintegrator (e.g. calcium carbonate, carboxymethylcellulose calcium, sodium starch glycollate, crospovidone etc.), a binder (e.g. alpha-starch, gum arabic, microcrystalline cellulose, carboxymethylcellulose, polyvinylpyrrolidone, hydroxypropylcellulose, cyclodextrin, etc.), and an optional lubricant (e.g., talc, magnesium stearate, polyethylene glycol 6000, etc.), for instance, are added to the active component or components (e.g., active) and the resulting composition is compressed. Where necessary the compressed product is coated, e.g., known methods for masking the taste or for enteric dissolution or sustained release. Suitable coating materials include, but are not limited to ethyl-cellulose, hydroxymethylcellulose, polyoxyethylene glycol, cellulose acetate phthalate, hydroxypropylmethylcellulose phthalate, and Eudragit (Rohm & Haas, Germany; methacrylic-acrylic copolymer).
Other physiologically acceptable compounds include wetting agents, emulsifying agents, dispersing agents or preservatives that are particularly useful for preventing the growth or action of microorganisms. Various preservatives are well known and include, for example, phenol and ascorbic acid. One skilled in the art would appreciate that the choice of pharmaceutically acceptable carrier(s), including a physiologically acceptable compound depends, for example, on the route of administration of the active agent(s) and on the particular physio-chemical characteristics of the active agent(s).
In certain embodiments the excipients are sterile and generally free of undesirable matter. These compositions can be sterilized by conventional, well-known sterilization techniques. For various oral dosage form excipients such as tablets and capsules sterility is not required. The USP/NF standard is usually sufficient.
In certain therapeutic applications, the compositions of this invention are administered, e.g., topically administered or administered to the oral or nasal cavity, to a patient suffering from infection or at risk for infection or prophylactically to prevent dental caries or other pathologies of the teeth or oral mucosa characterized by microbial infection in an amount sufficient to prevent and/or cure and/or at least partially prevent or arrest the disease and/or its complications. An amount adequate to accomplish this is defined as a “therapeutically effective dose.” Amounts effective for this use will depend upon the severity of the disease and the general state of the patient's health. Single or multiple administrations of the compositions may be administered depending on the dosage and frequency as required and tolerated by the patient. In any event, the composition should provide a sufficient quantity of the active agents of the formulations of this invention to effectively treat (ameliorate one or more symptoms in) the patient.
The concentration of active agent(s) can vary widely, and will be selected primarily based on activity of the active ingredient(s), body weight and the like in accordance with the particular mode of administration selected and the patient's needs. Concentrations, however, will typically be selected to provide dosages ranging from about 0.1 or 1 mg/kg/day to about 50 mg/kg/day and sometimes higher. Typical dosages range from about 3 mg/kg/day to about 3.5 mg/kg/day, preferably from about 3.5 mg/kg/day to about 7.2 mg/kg/day, more preferably from about 7.2 mg/kg/day to about 11.0 mg/kg/day, and most preferably from about 11.0 mg/kg/day to about 15.0 mg/kg/day. In certain preferred embodiments, dosages range from about 10 mg/kg/day to about 50 mg/kg/day. In certain embodiments, dosages range from about 20 mg to about 50 mg given orally twice daily. It will be appreciated that such dosages may be varied to optimize a therapeutic and/or phophylactic regimen in a particular subject or group of subjects.
In certain embodiments, the active agents of this invention are administered to the oral cavity. This is readily accomplished by the use of lozenges, aersol sprays, mouthwash, coated swabs, and the like.
In certain embodiments, the active agent(s) of this invention are administered topically, e.g., to the skin surface, to a topical lesion or wound, to a surgical site, and the like.
In certain embodiments the active agents of this invention are administered systemically (e.g., orally, or as an injectable) in accordance with standard methods well known to those of skill in the art. In other preferred embodiments, the agents, can also be delivered through the skin using conventional transdermal drug delivery systems, i.e., transdermal “patches” wherein the active agent(s) are typically contained within a laminated structure that serves as a drug delivery device to be affixed to the skin. In such a structure, the drug composition is typically contained in a layer, or “reservoir,” underlying an upper backing layer. It will be appreciated that the term “reservoir” in this context refers to a quantity of “active ingredient(s)” that is ultimately available for delivery to the surface of the skin. Thus, for example, the “reservoir” may include the active ingredient(s) in an adhesive on a backing layer of the patch, or in any of a variety of different matrix formulations known to those of skill in the art. The patch may contain a single reservoir, or it may contain multiple reservoirs.
In one embodiment, the reservoir comprises a polymeric matrix of a pharmaceutically acceptable contact adhesive material that serves to affix the system to the skin during drug delivery. Examples of suitable skin contact adhesive materials include, but are not limited to, polyethylenes, polysiloxanes, polyisobutylenes, polyacrylates, polyurethanes, and the like. Alternatively, the drug-containing reservoir and skin contact adhesive are present as separate and distinct layers, with the adhesive underlying the reservoir which, in this case, may be either a polymeric matrix as described above, or it may be a liquid or hydrogel reservoir, or may take some other form. The backing layer in these laminates, which serves as the upper surface of the device, preferably functions as a primary structural element of the “patch” and provides the device with much of its flexibility. The material selected for the backing layer is preferably substantially impermeable to the active agent(s) and any other materials that are present.
Other formulations for topical delivery include, but are not limited to, ointments, gels, sprays, fluids, and creams. Ointments are semisolid preparations that are typically based on petrolatum or other petroleum derivatives. Creams containing the selected active agent are typically viscous liquid or semisolid emulsions, often either oil-in-water or water-in-oil. Cream bases are typically water-washable, and contain an oil phase, an emulsifier and an aqueous phase. The oil phase, also sometimes called the “internal” phase, is generally comprised of petrolatum and a fatty alcohol such as cetyl or stearyl alcohol; the aqueous phase usually, although not necessarily, exceeds the oil phase in volume, and generally contains a humectant. The emulsifier in a cream formulation is generally a nonionic, anionic, cationic or amphoteric surfactant. The specific ointment or cream base to be used, as will be appreciated by those skilled in the art, is one that will provide for optimum drug delivery. As with other carriers or vehicles, an ointment base should be inert, stable, nonirritating and nonsensitizing.
As indicated above, various buccal, and sublingual formulations are also contemplated.
In certain embodiments, one or more active agents of the present invention can be provided as a “concentrate”, e.g., in a storage container (e.g., in a premeasured volume) ready for dilution, or in a soluble capsule ready for addition to a volume of water, alcohol, hydrogen peroxide, or other diluent.
While the invention is described with respect to use in humans, it is also suitable for animal, e.g., veterinary use. Thus certain preferred organisms include, but are not limited to humans, non-human primates, canines, equines, felines, porcines, ungulates, largomorphs, and the like.
The foregoing formulations and administration methods are intended to be illustrative and not limiting. It will be appreciated that, using the teaching provided herein, other suitable formulations and modes of administration can be readily devised.
Home Health Care Product Formulations.
In certain embodiments, one or more of the antimicrobial peptides (AMPs) and/or chimeric moieties described herein are incorporated into healthcare formulations, e.g., for home use. Such formulations include, but are not limited to toothpaste, mouthwash, tooth whitening strips or solutions, contact lens storage, wetting, or cleaning solutions, dental floss, toothpicks, toothbrush bristles, oral sprays, oral lozenges, nasal sprays, aerosolizers for oral and/or nasal application, wound dressings (e.g., bandages), and the like.
The formulation of such health products is well known to those of skill, and the antimicrobial peptides and/or chimeric constructs are simply added to such formulations in an effective dose (e.g., a prophylactic dose to inhibit dental carie formation, etc.).
For example, toothpaste formulations are well known to those of skill in the art. Typically such formulations are mixtures of abrasives and surfactants; anticaries agents, such as fluoride; tartar control ingredients, such as tetrasodium pyrophosphate and methyl vinyl ether/maleic anhydride copolymer; pH buffers; humectants, to prevent dry-out and increase the pleasant mouth feel; and binders, to provide consistency and shape (see, e.g., Table 12). Binders keep the solid phase properly suspended in the liquid phase to prevent separation of the liquid phase out of the toothpaste. They also provide body to the dentifrice, especially after extrusion from the tube onto the toothbrush.
Table 13 lists typical ingredients used in formulations; the final combination will depend on factors such as ingredient compatibility and cost, local customs, and desired benefits and quality to be delivered in the product. It will be recognized that one or more antimicrobial peptides and/or chimeric constructs described herein can simply be added to such formulations or used in place of one or more of the other ingredients.
One illustrative formulation described in U.S. Pat. No. 6,113,887 comprises (1) a water-soluble bactericide selected from the group consisting of pyridinium compounds, quaternary ammonium compounds and biguanide compounds in an amount of 0.001% to 5.0% by weight, based on the total weight of the composition; (2) a cationically-modified hydroxyethylcellulose having an average molecular weight of 1,000,000 or higher in the hydroxyethylcellulose portion thereof and having a cationization degree of 0.05 to 0.5 mol/glucose in an amount of 0.5% to 5.0% by weight, based on the total weight of the composition; (3) a surfactant selected from the group consisting of polyoxyethylene polyoxypropylene block copolymers and alkylolamide compounds in an amount of 0.5% to 13% by weight, based on the total weight of the composition; and (4) a polishing agent of the non-silica type in an amount of 5% to 50% by weight, based on the total weight of the composition. In certain embodiments, the antimicrobial peptide(s) and/or chimeric construct(s) described herein can be used in place of the bactericide or in combination with the bactericide.
Similarly, mouthwash formulations are also well known to those of skill in the art. Thus, for example, mouthwashes containing sodium fluoride are disclosed in U.S. Pat. Nos. 2,913,373, 3,975,514, and 4,548,809, and in US Patent Publications US 2003/0124068 A1, US 2007/0154410 A1, and the like. Mouthwashes containing various alkali metal compounds are also known: sodium benzoate (WO 9409752); alkali metal hypohalite (US 20020114851A1); chlorine dioxide (CN 1222345); alkali metal phosphate (US 2001/0002252 A1, US 2003/0007937 A1); hydrogen sulfate/carbonate (JP 8113519); cetylpyridium chloride (CPC) (see, e.g., U.S. Pat. No. 6,117,417, U.S. Pat. No. 5,948,390, and JP 2004051511). Mouthwashes containing higher alcohol (see, e.g., US 2002/0064505 A1, US 2003/0175216 A1); hydrogen peroxide (see, e.g., CN 1385145); CO2 gas bubbles (see, e.g., JP 1275521 and JP 2157215) are also known. In certain embodiments, these and other mouthwash formulations can further comprise one or more of the AMPs or compound AMPs of this invention.
Contact lens storage, wetting, or cleaning solutions, dental floss, toothpicks, toothbrush bristles, oral sprays, oral lozenges, nasal sprays, and aerosolizers for oral and/or nasal application, and the like are also well known to those of skill in the art and can readily be adapted to incorporate one or more antimicrobial peptide(s) and/or chimeric construct(s) described herein.
The foregoing home healthcare formulations and/or devices are meant to be illustrative and not limiting. Using teaching provided herein, the antimicrobial peptide(s) and/or chimeric construct(s) described herein can readily be incorporated into other products.
IV. Kits.In another embodiment this invention provides kits for the inhibition of an infection and/or for the treatment and/or prevention of dental caries in a mammal. The kits typically comprise a container containing one or more of the active agents (i.e., the antimicrobial peptide(s) and/or chimeric construct(s)) described herein. In certain embodiments the active agent(s) can be provided in a unit dosage formulation (e.g., suppository, tablet, caplet, patch, etc.) and/or may be optionally combined with one or more pharmaceutically acceptable excipients.
In certain embodiments the kits comprise one or more of the home healthcare product formulations described herein (e.g., toothpaste, mouthwash, tooth whitening strips or solutions, contact lens storage, wetting, or cleaning solutions, dental floss, toothpicks, toothbrush bristles, oral sprays, oral lozenges, nasal sprays, aerosolizers for oral and/or nasal application, and the like).
In certain embodiments kits are provided for detecting and/or locating and/or quantifying certain target microorganisms and/or cells or tissues comprising certain target microorganisms, and/or prosthesis bearing certain target microorganisms, and/or biofilms comprising certain target microorganisms. In various embodiments these kits typically comprise a chimeric moiety comprising a targeting moiety and a detectable label as described herein and/or a targeting moiety attached to an affinity tag for use in a pretargeting strategy as described herein.
In addition, the kits optionally include labeling and/or instructional materials providing directions (i.e., protocols) for the practice of the methods or use of the “therapeutics” or “prophylactics” or detection reagents of this invention. Certain instructional materials describe the use of one or more active agent(s) of this invention to therapeutically or prophylactically to inhibit or prevent infection and/or to inhibit the formation of dental caries. The instructional materials may also, optionally, teach preferred dosages/therapeutic regiment, counter indications and the like.
While the instructional materials typically comprise written or printed materials they are not limited to such. Any medium capable of storing such instructions and communicating them to an end user is contemplated by this invention. Such media include, but are not limited to electronic storage media (e.g., magnetic discs, tapes, cartridges, chips), optical media (e.g., CD ROM), and the like. Such media may include addresses to internet sites that provide such instructional materials.
EXAMPLESThe following examples are offered to illustrate, but not to limit the claimed invention.
Example 1 Design and Activity of a “Dual-Targeted” Antimicrobial PeptideNumerous reports have indicated the important role of human normal flora in the prevention of microbial pathogenesis and disease. Evidence suggests that infections at mucosal surfaces result from the outgrowth of subpopulations or clusters within a microbial community, and are not linked to one pathogenic organism alone. In order to preserve the protective normal flora while treating the majority of infective bacteria in the community, a tunable therapeutic is necessary that can discriminate between benign bystanders and multiple pathogenic organisms. Here we describe the proof-of-principle for such a multi-targeted antimicrobial: a multiple-headed specifically-targeted antimicrobial peptide (MH-STAMP). The completed MH-STAMP, M8(KH)-20, displays specific activity against targeted organisms in vitro (Pseudomonas aeruginosa and Streptococcus mutans) and can remove both species from a mixed planktonic culture with little impact against untargeted bacteria. These results demonstrate that a functional, dual-targeted molecule can be constructed from wide-spectrum antimicrobial peptide precursor.
IntroductionFor nearly 30 years antimicrobial peptides (AMPs) have been rigorously investigated as alternatives to small molecule antibiotics and potential solutions to the growing crisis of antibiotic resistant bacterial infections [1, 2]. Numerous reports have characterized potential AMPs from natural sources, and a great body of work has been carried out designing “tailor-made” AMPs due to the approachable nature of solid-phase peptide synthesis (SPPS) [3, 4]. Several examples of the latter have shown remarkable activities in vitro against fungi, Gram-positive and Gram-negative bacteria, as well as some enveloped viruses [5].
Unlike small molecule antibiotics that may lose activity when their basic structures are modified even incrementally, peptides are a convenient canvas for molecular alteration. AMPs can be optimized through the incorporation of more or less hydrophobic or charged amino acids, which has been shown to affect selectivity for Gram-positive, Gram-negative or fungal membranes [6, 7]. Additionally, lysine residues can be utilized to improve AMP activity per μM. In this approach, multiple AMP chains can be attached to a single peptide scaffold through branching from lysine epsilon-amines [8, 9]. AMP activity can be specifically tuned through the attachment of a targeting peptide region, as described for a novel class of molecules, the specifically-targeted antimicrobial peptides, or STAMPs [10, 11]. These chimeric molecules can consist of functionally independent targeting and killing moieties within a linear peptide sequence. A pathogenic bacterium recognized (i.e. bound) by the targeting peptide can be eliminated from a multi-species community with little impact to bystander normal flora. As an extension of this concept, we hypothesized that a STAMP could be constructed with multiple targeting peptide “heads” attached to a single AMP by utilizing a central lysine residue branch point. Potentially, targeting “heads” could be specific for the same pathogen, or have different binding profiles. Utilizing the former approach, microbial resistance evolution linked to a targeting peptide could be inhibited or reduced, as no single microbial population would have the genetic diversity necessary to mutate multiple discrete targeting peptide receptors in one cell [12].
Multi-headed STAMP (MH-STAMP) molecules with differing bacterial targets may have appeal in treating poly-microbial infections, or where it may be advantageous to remove a cluster of biofilm constituents without utilizing several distinct molecules; for example in the simultaneously treatment of dental caries and periodontitis, or in the eradication of the Propionibacteria spp. and Staphylococcus spp. involved in acne and skin infections, respectively.
In this example, we present the proof-of-principle design, synthesis and in vitro activity of such a MH-STAMP, M8(KH)-20. Previously, we identified two functional STAMP targeting domains, one with specific recognition of the cariogenic pathogen S. mutans [10], and the other with Pseudomonas spp.-level selectivity [13]. Conjoined to a normally wide-spectrum linear AMP, we observed antimicrobial effects directed specifically to P. aeruginosa and S. mutans in vitro. Additionally, treatment of mixed bacterial communities with the multi-headed MH-STAMP resulted in the specific eradication of the target organisms with little impact on bystander population levels.
Materials and MethodsBacterial Strains and Growth Conditions
P. aeruginosa ATCC 15692, Klebsiella pneumoniae KAY 2026 [14], Escherichia coli DH5α (pFW5, spectinomycin resistance) [15], Staphylococcus aureus Newmann [16], and Staphylococcus epidermidis ATCC 35984 were cultivated under aerobic conditions at 37° C. with vigorous shaking Aerobic Gram-negative organisms were grown in Lauri-Bertaini (LB) broth and Gram-positive bacteria in Brain-heart infusion (BHI) broth. Streptococcus mutans JM11 (spectinomycin resistant, UA140 background) was grown in Todd-Hewitt (TH) broth under anaerobic conditions (80% N2, 15% CO2, 5% H2) at 37° C. [17]. All bacteria were grown overnight to an OD600 of 0.8-1.0 prior to appropriate dilution and antimicrobial testing.
Synthesis of Multi-Head STAMP Peptides
Conventional solid-phase peptide synthesis (SPPS) methodologies were utilized for the construction of all peptides shown in
Synthesis progression was monitored by the ninhydrin test, and completed peptides cleaved from the resin with 95% TFA utilizing appropriate scavengers, and precipitated in methyl tert-butyl ether. Purification and MH-STAMP quality was confirmed by HPLC (Waters, Milford, Mass.) using a linear gradient of increasing mobile phase (acetonitrile 10 to 90% in water with 0.1% TFA) and a Waters XBridge BEH 130 C18 column (4.6×100 mm, particle size 5 μm). Absorbance at 215 nm was utilized as the monitoring wavelength, though 260 and 280 nm were also collected. LC spectra were analyzed with MassLynx Software v.4.1 (Waters). Matrix-assisted laser desorption ionization (MALDI) mass spectroscopy was utilized to confirm correct peptide mass (Voyager System 4291, Applied Biosystems) [18].
MIC Assay
Peptides were evaluated for basic antimicrobial activity by broth microdilution, as described previously [10, 11]. Briefly, 1×105 cfu/mL bacteria were diluted in TH (S. mutans), or Mueller-Hinton (MH) broth (all other organisms) and distributed to 96-well plates. Serially-diluted (2-fold) peptides were then added and the plates incubated at 37° C. for 18-24 h. Peptide MIC was determined as the concentration of peptide that completely inhibited organism growth when examined by eye (clear well). All experiments were conducted 10 times.
Post-Antibiotic Effect Assay
The activity and selectivity of MH-STAMPs after a 10 min incubation was determined by growth retardation experiments against targeted and untargeted bacteria in monocultures, as described previously [10, 11]. Cells from overnight cultures were diluted to ˜5×106 cfu/mL in MH (or TH with 1% sucrose for S. mutans), normalized by OD600 0.05-0.1 and seeded to 96-well plates. Cultures were then grown under the appropriate conditions for 2 h (3 h for S. mutans) prior to the addition of peptides for 10 min. Plates were then centrifuged at 3000×g for 5 min, the supernatants discarded, fresh medium returned (MH or TH without sucrose for S. mutans), and incubation resumed. Bacterial growth after treatment was then monitored over time by OD600.
Microbial Population Shift Assay
Mixed planktonic populations of P. aeruginosa, E. coli, S. epidermidis, and S. mutans were utilized to examine the potential of MH-STAMPs to direct species composition within a culture after treatment. Samples were prepared containing: ˜6×104 cfu/mL S. mutans, ˜2×104 cfu/mL E. coli, ˜2×104 cfu/mL S. epidermidis, and ˜0.5×104 cfu/mL P. aeruginosa in BHI (mixed immediately before peptide addition). Peptide (10 μM) or mock-treatment (1×PBS) was then added and samples were incubated at 37° C. for 24 h under anaerobic conditions (80% N2, 15% CO2, 5% H2). After incubation, samples were serially diluted (1:10) in 1×PBS and aliquots from each dilution were then spotted to agar plates selective for each species in the mixture: TH plus 800 μg/mL spectinomycin (S. mutans), LB plus 25 μg/mL ampicillin (P. aeruginosa), LB plus 200 μg/mL spectinomycin (E. coli), and mannitol salt agar (MSA, S. epidermidis) in order to quantitate survivors from each species. Plates were then incubated 37° C. under aerobic conditions (TH plates were incubated anaerobically) and colonies counted after 24 h to determine survivors. Expected colony morphologies were observed for each species when plated on selective media. Gram stains and direct microscopic observation (from select isolated colonies) were undertaken to confirm species identity (data not shown). The detection limit of the assay was 200 cfu/mL.
ResultsDesign and Synthesis of Multi-Headed STAMPs
We constructed a prototype MH-STAMP from the well-established targeting peptides KH (specific to Pseudomonas spp) and M8 (specific for Streptococcus mutans). The wide-spectrum antimicrobial peptide BD2.20 was utilized as the base AMP for all MH171 STAMP construction. BD2.20 is a novel synthetic AMP with a cationic and amphipathic residue arrangement, which has robust MICs against a variety of Gram-negative and Gram-positive organisms (Table 14). For the synthesis of MH-STMAP M8(KH)-20 (construct presented in
The non-binding “blank” targeting peptide BL-1 was incorporated into the synthesis scheme in place of KH or M8 to construct variant MH-STAMPs possessing a single functional targeting head: M8(BL)-20 and BL(KH)-20. The correct MW and acceptable purity were observed for these MH-STAMPs (
General Antimicrobial Activity of Multi-Head Constructs
After synthesis, the completed MH-STAMPs were evaluated for general antimicrobial activity by MIC against a panel of bacteria. As shown in Table 14, the MH-STAMP constructs M8(KH)-20, BL(KH)-20, and M8(BL)-20 were found to have similar activity profiles to that of BD2.20 for the organisms examined (less than two titration steps in 10-fold difference). Additionally, we observed a difference in general susceptibility between P. aeruginosa and the other organisms tested, suggesting this bacterium is more resistant to BD2.20. Overall, these data indicate that the addition of the targeting domains to the base sequence was tolerated and did not completely inhibit the activity of the antimicrobial peptide.
Peptide selectivity could not be determined utilizing these methods, as STAMPs and their parent AMP molecules often display similar MICs, but have radically different antimicrobial kinetics and selectivity due to increased specific-killing mediated by the targeting regions [10, 11]. Therefore, we performed different experiments to test for antimicrobial selectivity and functional MH-STAMP construction.
3.3 Selectivity and Post-Antibiotic Effect of MH-STAMP Constructs
MH-STAMP antimicrobial kinetics was ascertained utilizing a variation of the classical post-antibiotic effect assay, which measures the ability of an agent to affect an organism's growth after a short exposure period. Monocultures of MH-STAMP-targeted and untargeted organisms were exposed to M8(KH)-20, M8(BL)-20, BL(KH)-20, or unmodified BD2.20, then allowed to recover. As shown in
Ability of MH-STAMPs to Direct a “Population Shift” within a Mixed Species Population
We hypothesized that potential MH-STAMP dual-functionality could affect a particular set of bacteria within a mixed population, thereby promoting the outgrowth of non-targeted organisms and “shifting” the constituent makeup. To examine this possibility, defined mixed populations of planktonic cells were treated continuously and the make-up of the community examined after 24 h. As shown in
Our results indicate that we have successfully constructed a STAMP with dual antimicrobial specificities controlled by the targeting peptides present in the molecule; KH for Pseudomonas spp, M8 for S. mutans. In a closed multi-species system (
The emergence of metagenomics and the development of more sensitive molecular diagnostics has driven an increase in the understanding of human-associated microbial ecologies and host-microbe interactions [19-21]. At mucosal surfaces, it has become clear that our bodies harbor an abundance of residential flora which may impact innate and humoral immunity, nutrient availability, protection against pathogens, and even host physiology [22-25]. Furthermore, findings have indicated that shifts in the diversity of normal flora are associated with negative clinical consequences; for example the overgrowth of S. mutans in the oral cavity during cariogenesis (linked to the uptake of sucrose) or the antibiotic-assisted colonization of the intestine by Clostridium difficle [26, 27]. Other population shifts may be linked to axilla odor (Corynebacteria spp) [28, 29], or even host obesity. Given the quantity and diversity of microbes present, pathogenesis at mucosal surfaces is not likely to be associated with the overgrowth of a single strain or species. More often, it is a population shift resulting in the predominance of two or more species; for example the persistence of Burkholderia cepacia and P. aeruginosa in cystic fibrosis airway or Treponema denticola and Porphymonas gingivalis and other “red cluster” organisms in gingivitis [30, 31]. In many cases (such as the latter) these species may have only distant phylogenetic relationships and display differential susceptibilities to antibiotic therapies resulting in persistent disease progression despite treatment [32, 33]. Currently, available treatments for infections of mucosal surfaces are largely non-specific (traditional small-molecule antibiotics, mechanical removal), and thus are not effective in retaining flora or shifting the constituent balance back to a health-associated composition [34]. There is a need for a therapeutic treatment that can selectively target multiple pathogens, regardless of their phylogenetic relationship, and MH-STAMPs can help achieve this goal.
In monoculture experiments (
Although more rigorous studies and a more medically relevant combination of pathogen targets is desirable, these findings indicate that it is possible to design an antimicrobial peptide-based therapeutic with multiple and defined fidelities in vitro. MH-STAMPs may help improve human health through the promotion of healthy microbial constituencies.
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The mixture of coupling reagent HATU (5 eq. excess, 10 mg) and purpurin-18 (MW 564, 5 eq excess, 15 mg) in 600 mL dry dichloromethane (DCM):DMF:dimethylsulphoxide (DMSO) (1:1:1 (v/v)) was added to the peptide resin (1 molar equivalent, 15 mg) which was swelled by placing in minimal DMF for 30 min prior to reaction. 26 μL (10 molar equivalents) DIPEA was then added to the reaction flask to initiate the reaction. The reaction mixture was protected with argon and stirred at room temperature for 3 h.
After finishing, the reaction mixture was then passed down a sintered glass filtered vial and extensively washed with DMF and DCM to remove all waste reagents. The resin was then dried overnight in vacuum, and cleaved with 1 ml of trifluoroacetic acid (TFA)/thioanisole/water/EDT (10/0.5/0.5/025) for 2 hr at room temperature, and the cleavage solution was precipitated with 10 mL methyl-tert butyl ether. The precipitate was washed twice with the same amount of ether.
Example 3 Synthesis of Peptide-CSA ConjugateTo the fully protected peptide (solution of B43-GGG (FIDSFIRSF-GGG, 0.025 mmol) and tri-Boc-CSA-15 (0.0125 mol) in 300 μL DMF, DCC (7.7 mg), HOBt (5.1 mg) and 13 μL DIEA were added in iced-bath. After stirred at room temperature for four days, the reaction mixture was poured into 5 ml water and extracted with chloroform (5×3 mL). The CHCl3 extract was evaporated under vacuum and dried in a lyophilizer overnight. The dried CHCl3 extracts was then dissolved in 1 mL DCM followed by added 1 mL of TFA in iced-bath. The reaction mixture was further stirred at room temperature for 2 hours and precipitated with methyl tert-butyl ether (10 mL). The precipitate was further washed once with the same amount ether and dried in vacuum.
Example 4 Systemically Designed STAMPS Against S. MutansWe previously reported a novel strategy of “targeted-killing” with the design of narrow-spectrum molecules known as specifically-targeted antimicrobial peptides (STAMPs). Construction of these molecules requires the identification and the subsequent utilization of two conjoined yet functionally independent peptide components: the targeting and killing regions. In this study, we sought to design and synthesize a large number of STAMPs targeting Streptococcus mutans, the primary etiological agent of human dental caries, in order to identify candidate peptides with increased killing speed and selectivity when compared with their unmodified antimicrobial peptides (AMP) precursors. We hypothesized that a combinatorial approach utilizing a set number of AMP, targeting, and linker regions, would be an effective method for the identification of STAMPs with the desired level of activity. STAMPs composed of the S. mutans binding peptide 2—1 and the AMP PL-135 displayed selectivity at minimal inhibitory concentrations after incubation for 18-24 h. STAMPs where PL-135 was replaced by the B-33 killing domain exhibited both selectivity and rapid killing within one minute of exposure. These results suggest that potent and selective STAMP molecules can be designed and improved via a tunable “building-block” approach.
IntroductionPathogenic microorganisms have been a continuous source of human suffering and mortality throughout the course of human history and have spurred the clinical development of novel therapeutics. Even today, the overall burden of infectious disease remains high, constituting a leading (and rising) cause of death worldwide (12, 13). The conventional medical response to bacterial infections, small molecule antibiotics, have become less effective against emerging pathogens due to the evolution of drug-resistance stemming in part from the misuse of antibiotics (11). To counter the rapid progression of antibiotic resistance there is an urgent need for the development of novel lead compounds for clinical applications.
Our strategy for creating new antibacterial agents is based on the addition of a targeting peptide to an existing broad-spectrum antimicrobial peptide, thereby generating a specifically-targeted antimicrobial peptide (STAMP) selective for a particular bacterial species or strain. A completed STAMP consists of conjoined but functionally independent targeting and killing regions, separated by a small flexible linker, all within a linear peptide sequence. The STAMP targeting region drives enhancement of antimicrobial activity by increasing binding to the surface of a targeted pathogen, utilizing specific determinants such as overall membrane hydrophobicity and charge, pheromone receptors, etc., which in turn leads to increased selective accumulation of the killing moiety (6, 7).
As both the killing and targeting regions of the STAMP are linear peptides, we approached the design process using a tunable combinatorial methodology where, for example, the targeting peptide component is held constant, while a number of killing peptides are conjoined utilizing a variety of linker molecules, or vise versa, in order to generate a library of related STAMPs. Previously, we successfully demonstrated a pilot version of this approach when constructing G10KHc (6), a STAMP with Pseudomonas-spp selective activity, and when designing C16G2 (7), a STAMP specific for Streptococcus mutans, the leading causative agent of human tooth decay. In this study, synthetic targeting and antimicrobial peptide libraries were utilized as building blocks to generate a number of novel STAMPs with high S. mutans-selective activity. STAMPs designed by these methods were then improved through tuning the linker and killing peptides present to yield completed lead STAMP molecules that demonstrated activity against S. mutans biofilms.
Materials and MethodsReagents.
Wang resin, Rink-MBHA resin, p-Benzyloxybenzyl alcohol resin (100-200 mesh), 9-fluorenylmethoxycarbonyl (Fmoc) amino acids, N-hydroxybenzotriazole hydrate (HOBT) and 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU) were obtained from Anaspec (San Jose, Calif.). All other solvents and reagents were purchased from Fisher Scientific (Pittsburgh, Pa.) at HPLC or peptide synthesis grade.
Bacterial Growth
All S. mutans (UA159) (1), Streptococcus gordonii Challis (DL 1), Streptococcus sobrinus ATCC 33478, and Streptococcus sanguinis NY101 strains were grown in Brain Heart Infusion (BHI) medium at 37° C. under anaerobic conditions (80% N2, 10% CO2, 10% H2) (6). Pseudomonas aeruginosa (PAK) (17), and Escherichia coli W3110 (20), were cultured in Luria-Bertani (LB) medium under an aerobic atmosphere at 37° C. Methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus faecium (VRE) were grown in BHI under aerobic conditions at 37° C. (4).
Peptide Syntheses and Purification.
Peptides were synthesized using standard solid phase (Fmoc) chemistry with an Apex 396 peptide synthesizer (AAPPTec, Louisville, Ky.) at a 0.01 mM scale. N-terminal deblocking during linear peptide synthesis was conducted with 0.6 mL of 25% (v/v) piperidine in dimethylformamide (DMF), followed by agitation for 27 min and wash cycles of dichlormethane DCM (1×1 mL) and NMP (7×0.8 mL). Subsequent amino acid coupling cycles were conducted with a mixture of Fmoc-protected amino acid (5 eq), HOBT (5 eq), HBTU (5 eq), DIEA (10 eq) in DMF (0.1 mL), and NMP (0.2 mL) with agitation for 45 min. The washing cycle was repeated before the next round of deprotection and coupling. After synthesis, peptides were washed in methanol and dried 24 h. Protected peptide was cleaved with 1 mL of trifluoroacetic acid (TFA)/thioanisole/water/1,2-ethanedithiol (10/0.5/0.5/025) for 3 h at room temperature and the resultant peptide solution was precipitated in methyl tert-butyl ether.
Analytical and preparative HPLC was conducted, as described previously (5, 9), to purify each peptide to 80-90%. Correct peptide mass was confirmed by matrix-assisted laser desorption/ionization mass spectroscopy (MALDI, Voyager instrument, Applied Biosystems), as described previously (9). Measurements were made in linear, positive ion mode with an α-cyano-4-hydroxycinnamic acid matrix (data not shown).
Acetylated and benzolated peptides derivatives (Ac135(L1)2—1 and bz135(L1)2—1, respectively) were synthesized by the same method used for N-terminal fluorescent labeling, described previously (7). Briefly, acetylation (acetic anhydrous) or benzyl addition (benzoatic acid) was undertaken after assembly of the linear sequence by adding to the resin (10 eq in DIEA) for 2 h.
Binding of Targeting Peptides. The binding of peptides 1—2, 1—3, 1—4, 1—6, 2—1, and 3—1 was assessed by fluorescent microscopy. S. mutans UA159 was grown overnight and diluted 1:5000 in fresh TH with 1% sucrose before seeding to 96-well plates (flat bottom). Biofilms were grown 24 h and the spent medium replaced with 1×PBS containing 25 μM peptide. After 5 min incubation at room temperature, the supernatants were removed and the biofilms washed 2× with 1×PBS and imaged by bright-field and fluorescence microscopy (Nikon E400). Digital images were collected and analyzed for semiquantitative binding assessments with the manufacturers supplied software (SPOT, Diagnostics) (6).
Minimum Inhibitory Concentrations (MICS) of Peptides.
Peptide MIC was determined by broth microdilution (6, 15). Briefly, two-fold serial dilutions of each peptide were prepared with 50% BHI medium+50% sterile water (for oral streptococci; all other bacteria were diluted in 1× Mueller-Hinton broth) at a volume of 100 μL per well in 96-well flat-bottom microtiter plates. The concentration of peptide for the first test round ranged from 500 to 2 μg/mL or 125 to 1 μg/mL. If activity was detected, a second round of MIC tests was conducted with concentrations of 62.5 to 0.5 μg/mL. In either case, the microtiter plate was inoculated with a bacterial cell suspension to a final concentration of ˜1×105 cells per mL and the plates were incubated at 37° C. for 16-20 h under the appropriate conditions. After incubation, absorbance at 600 nm (A600) was measured using a microplate UV-Vis spectrophotometer (Model 3550, BioRad, Hercules, Calif.) to assess cell growth. The MIC endpoint was calculated as the lowest concentration of antibacterial agent that completely inhibited growth or that produced at least 90% reduction in turbidity when compared with that of a peptide-free control. At least 10 independent tests were conducted per peptide. For peptides insoluble in aqueous solutions, stock solutions were prepared in methanol or ethanol and appropriate solvent controls were utilized. Cell growth was not affected by 5% (v/v) methanol or ethanol, as described previously (10).
Peptide Killing Kinetics.
To determine antimicrobial kinetics and specificity, assays similar to traditional time-kill experiments were performed, as described previously (6, 7). Briefly, overnight bacterial cultures were diluted in BHI to A600 0.08 and peptides were added as indicated. Aliquots were then removed at various intervals and diluted 1:50 in BHI and kept on ice until plating on appropriate growth medium. After 24 hours incubation, colonies were counted and the surviving cfu/mL determined. All assays were repeated at least 3 times and the average recovered cfu/mL were presented with standard deviations. Statistical analysis was conducted utilizing an unpaired Student's t-test.
Biofilm Growth Inhibitory Assays.
STAMPs were tested for anti-biofilm activity as described previously (6). Briefly, overnight cultures of S. mutans were diluted 1:50 in Todd-Hewitt (TH) broth medium supplemented with 0.5% sucrose and 100 μL of bacterial suspension was added to each well of a 96-well microtiter plate. After centrifugation, bacteria were then incubated under anaerobic conditions at 37° C. for 4 h. Supernatants were then removed and replaced with 25 μM peptide in 1×PBS for 30 s to 1 min, followed by removal, washing, and replacement with 100 μL fresh TH broth (without sucrose). Plates were then incubated at 37° C. under anaerobic conditions and the bacterial recovery monitored by recording A600 after 4 h incubation. An unpaired Student's t-test was utilized for statistical analysis.
ResultsSTAMPs consist of 3 regions: one targeting and one antimicrobial, connected via a flexible linker. In this report, we conjoined examples of each domain with a variety of linkers to construct a pool of initial STAMP candidates. These peptides were then evaluated for anti-S. mutans activity and selectivity, their designs improved, and the lead STAMPs evaluated against S. mutans biofilms.
Selection of Components and Initial STAMP Library Design.
As described elsewhere, we generated several novel S. mutans-specific binding peptides, including 2—4, (previously S3L1-10 (FIKDFIERF)) and 1—5, (previously S3L1-5 (WWYNWWQDW)) (7). From these base sequences, residues differing in hydrophobicity and/or charge were substituted at defined positions to yield a series of related targeting sequences that were then evaluated for binding to S. mutans biofilms. Several of the 1—5 variants, and one of the 2—4 variants, were found to retain biofilm binding (data not shown). These sequences (1—2; 1—3; 1—4; 1—6; 2—1; 3—1), as well as 1—5, were regarded in the present study as the pool of S. mutans targeting peptides for STAMP construction (shown in Table 15). For the antimicrobial component, we selected PL-135, a peptide based on an AMP isolated from tunicates (19), for the initial round of design (Library 1). We hypothesized that linker regions and attachment orientation would exert an influence on STAMP activity. Therefore, we initially conjugated each potential targeting peptide to the N or C terminus of PL-135 through six different linkers, as shown in Table 15 (GGG, designated L1; SAT, L3; ASASA, L5; PYP, L7; PSGSP, L8; PSPSP, L9) leading to the synthesis of 84 STAMPs.
Antimicrobial Activity of Initial STAMP Library.
To roughly gauge Library 1 STAMP antimicrobial activity and S. mutans-selectivity, MIC (minimal inhibitory concentration) assays were conducted against S. mutans and a panel of bacteria, including two oral streptococci, S. sanguinis and S. sobrinus (
Impact of Linker and Terminal Modification on STAMP Antimicrobial Activity.
We sought to investigate the impact of linker length or type, and N-terminal modification on the activity of STAMP 135(L1)2—1 from Library 1. As shown in Table 16, altered components included: 1) new linkers GGGG (G4) to GGGGGGG (G7), AAA (L2), AGA (L10), GAGAG (L11), 8-aminocaprylic acid (LC); 2) increased N-terminal aromacity (benzoic acid addition); 3) acetylation of N-terminus; or 4) component sequence inversion (135i(L1)2—1i). We observed MICs for these Library 2 STAMPs that were similar to, or 2-fold less-active, than that of the base STAMP 135(L1)2—1 (
Further Potential of PL-135-Based STAMPs.
Antiseptic mouthrinses, such as Listerine® (Warner-Lambert, Morris Plains, N.J.), are rapid-acting non-selective bactericidal agents that can inactivate viable bacteria within seconds of contact (3). In order for STAMPs to be useful mouthrinse ingredients, the antimicrobial kinetics must approach this scale. Therefore, the killing kinetics of our Library 1 and 2 STAMPs from Table 15 and
Tuning the Design of 2—1-Containing STAMPs.
To improve the identification of rapid-killing S. mutans STAMPs, we conjugated 2—1 with five AMPs selected from our previous studies (10), to construct Library 3: RWRWRWF (2c-4), FKKFWKWFRRF (B-33), IKQLLHFFQRF (B-38), RWRRLLKKLHHLLH (α-11), LQLLKQLLKLLKQF (a-7); attached at the C- or N-terminus. The linkers selected were L1, SGG (L2), L3 and LC. As shown in
STAMP Killing Kinetics Against Oral Bacteria.
Since the MIC assay measures antimicrobial activity after overnight incubation, large differences in killing rates between STAMPs and parental AMPs may be obscured in this assay, especially when the target organism is susceptible to the AMP (7, 9). To assess any significant selectivity and short-term antimicrobial activity of the Library 3 STAMPs, time-kill assays were performed against a variety of oral bacteria. Against the targeted bacterium S. mutans (examples shown in
Inhibition of Biofilm Growth.
Although rapid and selective killing of S. mutans monocultures was apparent from the data shown in
In this report, we present a novel strategy for the design and synthesis of STAMPs with activity against the oral pathogen S. mutans. Successful design was achieved through a tunable, building-block approach that utilized various combinations of antimicrobial, targeting, and linker STAMP peptide regions. Our results demonstrate that less-efficacious STAMPs could be improved when alternative killing regions were substituted in the design. While it remains unclear whether the alternative moieties were more active, or simply more conjugation tolerant, this process resulted in STAMPs that displayed killing kinetics against biofilms consistent with oral therapeutic applications. Additionally, more understanding was gained regarding AMP or targeting peptide orientation dependencies, impact of linker regions, and appropriate targeting peptide choice, which could positively impact future anti-S. mutans STAMP design and refinement.
From the data presented here, it is difficult to determine the precise mechanism for the S. mutans-selectivity. Previous studies with STAMPs have indicated that the enhanced selectivity for the targeted strain is due to the binding of the targeting peptide moiety (6, 7). Although detailed binding analysis was not conducted in this study, our results suggest that a similar targeting-mediated killing is occurring here: targeting peptides, independently selected for STAMP construction on the basis of their S. mutans-binding abilities, were required to enhance AMP antimicrobial activity and selectivity.
The data presented suggest that PL-135 may be inhibited by conjugation to other peptide subunits, as unmodified PL-135 displayed activity against S. mutans that was 2 to 4-fold higher than in progeny STAMPs, as shown in
Outside of PL-135-containing examples (and potentially some α-7 and α-11 molecules, see
Interestingly, 2—1 and 3—1 containing STAMPs were active against S. mutans, and the constructs with any other targeting peptide in Table 15, were not. Targeting peptides 1—2 through 1—6 are strongly hydrophobic, compared with 2—1 and 3—1 (8), and it may be possible that this characteristic limits the dissociation of these molecules from the hydrophobic components of the S. mutans cell wall, resulting in their inhibitory affect on AMPs when conjugated, similarly to some strong LPS-binding AMPs (14). However, the systematic building-block design strategy employed allowed us to generate a diverse array of STAMPs, allowing us to identify useful compounds despite these stumbling blocks.
In conclusion, this report details the rational design of S. mutans-selective STAMPs with enhanced antimicrobial killing kinetics and selectivity when compared to untargeted AMPs. The S. mutans-selective STAMPs were constructed using a tunable, combinatorial approach that generated a diverse number of STAMP sequences for antimicrobial evaluation and improvement; a process may serve as an example for the systematic development of novel selective antimicrobial agents. We propose that these STAMPs could be useful in the design of therapeutics against oral or other mucosal pathogens, where the high diversity of “probiotic” beneficial microflora limits the effectiveness of broad-spectrum antimicrobial agents.
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It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims. All publications, patents, and patent applications cited herein are hereby incorporated by reference in their entirety for all purposes.
Claims
1. A chimeric moiety, said moiety comprising:
- an effector attached to a peptide targeting moiety the amino acid sequence of said targeting moiety comprising the sequence GGSGSLSTFFRLFNRSFTQALGK (SEQ ID NO:60).
2. The chimeric moiety of claim 1, wherein the amino acid sequence of said targeting moiety is GGSGSLSTFFRLFNRSFTQALGK (SEQ ID NO:60).
3. The chimeric moiety of claim 1, wherein said effector comprises a moiety selected from the group consisting of a detectable label, an antimicrobial peptide, an antibiotic, and a photosensitizer.
4. The chimeric moiety of claim 1, wherein said effector comprises an antimicrobial peptide comprising the amino acid sequence of a peptide found in Table 2, Table 8, Table 9, or Table 10 or any antimicrobial peptide disclosed herein.
5. The chimeric moiety of claim 1, wherein said effector comprises an antibiotic found in Table 7.
6-14. (canceled)
15. The chimeric moiety of claim 1, wherein said targeting moiety is chemically conjugated to said effector.
16. The chimeric moiety of claim 15, wherein said targeting moiety is chemically conjugated to said effector via a linker.
17. The chimeric moiety of claim 15, wherein said targeting moiety is chemically conjugated to said effector via a linker comprising a polyethylene glycol (PEG).
18. The chimeric moiety of claim 15, wherein said targeting moiety is chemically conjugated to said effector via a non-peptide linker found in Table 11.
19. The chimeric moiety of claim 1, wherein said targeting moiety is linked directly to said effector.
20. The chimeric moiety of claim 1, wherein said targeting moiety is linked to said effector via a peptide linkage.
21. The chimeric moiety of claim 20, wherein the chimeric moiety is a fusion protein.
22. The chimeric moiety of claim 21, wherein said peptide linkage comprises a peptide linker found in Table 11.
23. The chimeric moiety of claim 20, wherein said chimeric moiety is functionalized with a polymer to increase serum halflife.
24. The chimeric moiety of claim 21, wherein said polymer comprises polyethylene glycol and/or a cellulose or modified cellulose.
25. A pharmaceutical composition comprising a chimeric moiety of claim 1 in a pharmaceutically acceptable carrier.
26. The composition of claim 25, wherein said composition is formulated as a unit dosage formulation.
27. The composition of claim 25, wherein said composition is formulated for administration by a modality selected from the group consisting of intraperitoneal administration, topical administration, oral administration, inhalation administration, transdermal administration, subdermal depot administration, and rectal administration.
28-45. (canceled)
46. The chimeric moiety of claim 1, wherein said effector comprises a photosensitizing agent.
47. (canceled)
48. The chimeric moiety of claim 46, wherein said photosensitizing agent is an agent selected from the group consisting of a porphyrinic macrocycle, a porphyrin, a chlorine, a crown ether, an acridine, an azine, a phthalocyanine, a cyanine, a psoralen, and a perylenequinonoid.
49. The chimeric moiety of claim 46, wherein said photosensitizing agent is an agent shown in any of FIGS. 1-11.
50. The chimeric moiety of claim 46, wherein said photosensitizing agent is attached to said targeting peptide by a non-peptide linker.
51. The chimeric moiety of claim 46, wherein said photosensitizing agent is attached to said targeting peptide by a linker comprising a polyethylene glycol (PEG).
52. The chimeric moiety of claim 46, wherein said photosensitizing agent is attached to said targeting peptide by a non-peptide linker found in Table 11.
53-58. (canceled)
Type: Application
Filed: Feb 15, 2013
Publication Date: May 22, 2014
Applicant: The Regents of the University of California (Oakland, CA)
Inventor: The Regents of the University of California
Application Number: 13/768,839
International Classification: A01N 63/00 (20060101);
