Treatment of Mycobacterial diseases by administration of bacterial/permeability-increasing protein products
The present invention relates to methods for treating a subject suffering from infection with Mycobacteria, such as M. leprae or M. tuberculosis comprising administering to the subject a composition comprising a bactericidal/permeability-inducing (BPI) protein product alone or in combination with administration of an anti-Mycobacterial antibiotic.
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This is a continuation-in-part of co-pending U.S. patent application Ser. No. 08/031,145, filed Mar. 12, 1993.BACKGROUND OF THE INVENTION
The present invention relates to methods of treating a subject suffering from infection with Mycobacteria by administration of Bactericidal/Permeability-Increasing Protein (BPI) protein products. Mycobacterium is a non-motile, acid-fast, aerobic, genus of bacteria known to cause grave human and animal diseases, such as tuberculosis and leprosy. Infections caused by M. avium are the most common form of disseminated bacterial disease in AIDS patients. Orme, et al., Infect. and Immun., 61 (1): 338-342 (1993).
The administration of conventional antibiotics to treat Mycobacterial infection is known in the art and has achieved varying success depending on the susceptibility of the bacterial strain, the efficacy and toxicity of the antibiotic(s) employed, the duration of treatment, and numerous other factors. Antimicrobials that have been employed alone or in combination to treat Mycobacterial infections, including those caused by M. tuberculosis include isoniazid, rifampin, ethambutol, p-aminosalicylic acid, pyrazinamide, streptomycin, capreomycin, cycloserine, ethionamide, kanamycin, amikacin, amithiozone, rifabutin, clofazimine, arithromycin, clarithromycin, ciprofloxacin and ofloxacin. McClatchy, Antimycobacterial Drugs: Mechanisms of Action, Drug Resistance, Susceptibility Testing, and Assays of Activity in Biological Fluids, pp. 134-197, In Antibiotics in Laboratory Medicine, 3rd ed., V. Lorian, ed. The Williams & Wilkins Co., Baltimore (1991). As many Mycobacterial strains are drug resistant, serious obstacles exist for control and successful treatment of tuberculosis and other Mycobactenal diseases. Id.
A variety of factors have made treatment of individuals afflicted with Mycobactenal diseases problematic. First, Mycobacteria possess a very hydrophobic cell wall that affords protection against the host's immune system. As Mycobacterial infections tend to be chronic, the pathologies of these organisms are generally due to host response. Also, many Mycobacterial strains are drug-resistant. These and other factors make the development of novel, effective methods for treating Mycobacterial diseases highly desirable.
Mycobacteria are readily distinguished from gram-negative and gram-positive bacteria by acid fast staining due to significant differences in cell wall structure. Gram-negative bacteria are characterized by a cell wall composed of a thin layer of peptidoglycan covered by an outer membrane of lipoprotein and lipopolysaccharide (LPS), whereas gram-positive bacteria have a cell wall with a thicker layer of peptidoglycan with attached teichoic acids, but no LPS. The Mycobacterial cell wall is rich in fatty acids, including a major constituent, lipoarabinomannan (LAM), which is widely distributed within the cell wall of Mycobacterium species. LAM has been purified from both M. leprae and M. tuberculosis. Hunter et al., J. Biol. Chem., 261: 12345-12351 (1986). LAM is a serologically active mannose containing phosphorylated lipopolysaccharide that may be membrane associated.
The complex physiological effects of LAM appear to be concentration, time, and source-dependent. For example, Chaterjee et al., Infect. and Immun., 60 (3): 1249-1253 (1992), reported that, in the first 24 hours following exposure, LAM from an avirulent strain of tuberculosis was 100-fold more potent at stimulating TNF secretion in mouse macrophages than LAM from a virulent strain. LAM concentrations of 0.01-10 μg/ml for the avirulent strain and 0.01-100 μg/ml for the virulent strain were tested, and increased LAM concentration was associated with increased TNF production with LAM from both species.
Macrophage-inhibitory effects of LAM have also been described in the art. LAM purified from both M. leprae and M. tuberculosis has been reported to be a potent in vitro inhibitor of T-cell lymphokine activation of mouse macrophages. Sibley et al., Infection and Immunity, 56 (5): 1232-1236 (1988). Because the principle efferent role of the macrophage in acquired resistance to intracellular pathogens requires activation by T-cell lymphokines, notably gamma-interferon (IFN-γ), macrophages whose activation-response is inhibited are severely compromised in their capacity for both enhanced microbicidal and tumoricidal activities.
In another study, Sibley et al., Clin. Exp. Immunol., 80 (1): 141-148 (1990), reported that pretreatment of mouse macrophages with 50 to 100 ug/ml LAM blocked macrophage activation by IFN-γ, but pretreatment with 10 μg/ml LAM did not affect macrophage activation. Thus, it is believed that low concentrations of LAM stimulate cytokine production, at least initially. However, higher concentrations of LAM (50-100 μg/ml or more) appear to block rather than promote macrophage function. Thus, the production of either too much or too little cytokine at different stages of Mycobacterial disease may contribute to Mycobacterial pathogenesis. New methods for blocking the above-characterized physiological effects of LAM molecules are a highly desirable goal in the treatment of subjects that are or that have been infected with Mycobacteria. For the same reasons, new methods by which fluids containing LAM can be decontaminated prior to administration into a subject are also desirable. Neutralization of even small amounts of LAM is desirable, because small amounts of LAM may have the physiological effect of stimulating cytokine production.
Of interest to the background of the invention are the disclosures of PCT/US88/00510, (WO 88/06038) published Aug. 25, 1988, indicating that certain poloxypropylene/polyoxyethylene nonionic surface-active block copolymers can be used with or without conventional antibiotics to treat infection with Mycobacterium. This reference cites studies suggesting that the effects of other nonionic surfactants on tuberculosis are most likely due to modification of surface lipids of Mycobacteria, and not to direct bactericidal effects on Mycobacteria. See e.g. Cornforth et al., Nature, 168: 150-153 (1951).
Bactericidal/permeability-increasing protein (BPI) is a protein isolated from the granules of mammalian polymorphonuclear neutrophils (PMN), which are blood cells essential in the defense against invading microorganisms. Human BPI protein has been isolated from PMN's by acid extraction combined with either ion exchange chromatography Elsbach, J. Biol. Chem., 254: 11000 (1979) or E. coli affinity chromatography, Weiss, et al., Blood, 69: 652 (1987), and has potent bactericidal activity against a broad spectrum of gram-negative bacteria. The molecular weight of human BPI is approximately 55,000 Daltons (55 kD). The amino acid sequence of the entire human BPI protein, as well as the DNA encoding the protein, have been elucidated in
BPI has been shown to be a potent bactericidal agent active against a broad range of gram-negative bacterial species. The cytotoxic effect of BPI was originally established to be highly specific to sensitive gram-negative species, with no toxicity being noted for other non-acid fast, gram-positive bacteria or for eukaryotic cells. The precise mechanism by which BPI kills bacteria is as yet unknown, but it is known that BPI must first attach to the surface of susceptible gram-negative bacteria. It is thought that this initial binding of BPI to the bacteria involves electrostatic interactions between the basic BPI protein and negatively charged sites on lipopolysaccharides (LPS). LPS has been referred to as endotoxin because of the potent inflammatory response that it stimulates. LPS induces the release of mediators by host inflammatory cells which may ultimately result in irreversible endotoxic shock. BPI binds to Lipid A, the most toxic and most biologically active component of LPS.
In susceptible bacteria, it is thought that BPI binding disrupts LPS structure, leads to an activation of bacterial enzymes that degrade phospholipids and peptidoglycans, alters the permeability of the cell's outer membrane, and ultimately causes cell death by an as yet unknown mechanism. BPI is also capable of neutralizing the endotoxic properties of LPS to which it binds. Because of its gram-negative bactericidal properties and its ability to neutralize LPS, BPI can be utilized for the treatment of mammals suffering from diseases caused by gram-negative bacteria, such as bacteremia or sepsis.
An approximately 25 kD proteolytic fragment corresponding to the amino-terminal portion of human BPI holoprotein possesses the antibacterial efficacy of the naturally-derived 55 kD human holoprotein. In contrast to the amino-terminal portion the carboxy-terminal region of the isolated human BPI protein displays only slightly detectable anti-bacterial activity. Ooi, et al., J. Exp. Med., 174: 649 (1991). A BPI amino-terminal fragment, expressed from a construct encoding approximately the first 199 amino acid residues of the human BPI holoprotein, has been produced by recombinant means as a 23 kD protein referred to as “rBPI23”. Gazzano-Santoro et al., Infect. Immun. 60: 4754-4761 (1992).
While BPI protein products are effective for treatment of conditions associated with gram-negative bacterial infection, there continues to exist a need in the art for products and methods for treatment of other bacterial infections such as infection with Mycobacteria.SUMMARY OF THE INVENTION
The present invention provides methods of treating a subject suffering from infection with Mycobacteria by administration of a composition comprising a BPI protein product. Therapeutic compositions according to the invention may be administered orally, systemically (such as by intravenous, intramuscular or other injection), or as an aerosol. Mycobacterial disease states subject to treatment according to the invention include tuberculosis, which can be caused by infection with M. tuberculosis, leprosy, which can be caused by infection with M. leprae, and diseases caused by M. avium and other Mycobacteria species. According to preferred methods, anti-Mycobacterial antibiotics such as previously identified and/or surfactants may be administered in combination with the BPI protein product to subjects suffering from infection with Mycobacteria.
According to another aspect of the present invention, compositions comprising a BPI protein product are administered to neutralize LAM's physiological effects on a host. For example, methods are provided for neutralizing the effect of low concentrations of LAM capable of stimulating cytokine production in a host. Methods are also provided for neutralizing the inhibitory effect that higher concentrations of Mycobacterial LAM (i.e. 100 μg/ml or more) have upon the interferon-mediated activation of macrophages. Specifically, a BPI protein product may be administered to an immunosuppressed subject failing to respond to microbes or tumor cells due to LAM-induced insensitivity of macrophages to activation by T-cell lymphokines.
According to a further aspect of the present invention, a BPI protein product is employed in methods for decontaminating a fluid containing LAM prior to administration of the fluid into a subject. Such decontamination methods of the invention involve contacting the fluid with the BPI protein product prior to administration, under conditions such that LAM forms a complex with the BPI protein product which can be removed from the fluid. Fluids subject to decontamination by the methods of this invention include, but are not limited to, blood, plasma, blood serum, bone marrow, isotonic solutions, pharmaceutical agents, and cell culture agents.
A further aspect of this invention relates to the use of a composition comprising a BPI protein product for the manufacture of a medicament for the therapeutic application of treating any of the aforementioned conditions or infections from which a subject might suffer.
Numerous additional aspects and advantages of the invention will become apparent to those skilled in the art upon considering the following detailed description of the invention, which describes presently preferred embodiments thereof.BRIEF DESCRIPTION OF THE FIGURES
The present invention relates to the discovery that a composition comprising a BPI protein product can be administered for effective treatment of a subject suffering from infection with Mycobacteria. In particular, the invention provides methods for treatment of leprosy and tuberculosis, grave diseases caused by the species M. leprae and M. tuberculosis, respectively. It is contemplated that the methods described herein may be used to treat infection with other Mycobacterial species, most notably M. avium and M. intracullulare (collectively known as “MAC”), but also M. marinum, M. fortuitum, M. chelonae, M. smegmatis, M. kansasii, M. bovis, M. hominis, M. gordonae and other parthogenic or opportunistic species. Beneficial effects of treatment with BPI protein products are expected to result from binding of the products to LAM and disruption of the bacterial cell wall components (with or without direct killing of the bacteria) in manner similar to that resulting from treatment of gram-negative disease states.
As used herein, “BPI protein product” includes naturally and recombinantly produced BPI protein; natural, synthetic, and recombinant biologically active polypeptide fragments of BPI protein; biologically active polypeptide variants of BPI protein or fragments thereof, including hybrid fusion proteins and dimers; and biologically active polypeptide analogs of BPI protein or fragments or variants thereof, including cysteine-substituted analogs. The BPI protein products administered according to this invention may be generated and/or isolated by any means known in the art. U.S. Pat. No. 5,198,541, the disclosure of which is hereby incorporated by reference, discloses recombinant genes encoding and methods for expression of BPI proteins including recombinant BPI holoprotein, referred to herein as rBPI50 and recombinant fragments of BPI. Co-owned, copending U.S. patent application Ser. No. 07/885,501 and a continuation-in-part thereof, U.S. patent application Ser. No. 08/072,063 filed May 19, 1993 which are hereby incorporated by reference, disclose novel methods for the purification of recombinant BPI protein products expressed in and secreted from genetically transformed mammalian host cells in culture and discloses how one may produce large quantities of recombinant BPI products suitable for incorporation into stable, homogeneous pharmaceutical preparations.
Biologically active fragments of BPI (BPI fragments) include biologically active molecules that have the same amino acid sequence as a natural human BPI holoprotein, except that the fragment molecule lacks amino-terminal amino acids, internal amino acids, and/or carboxy-terminal amino acids of the holoprotein. Nonlimiting examples of such fragments include an N-terminal fragment of natural human BPI of approximately 25 kD, described in Ooi et al., J. Exp. Med., 174: 649 (1991), and the recombinant expression product of DNA encoding N-terminal amino acids from residue 1 to about residue 200, including from about residue 1 to about residue 193 or 199 of natural human BPI, described in Gazzano-Santoro et al., Infect. Immun. 60: 4754-4761 (1992), and referred to as rBPI23. In that publication, an expression vector was used as a source of DNA encoding a recombinant expression product (rBPI23) having the 31-residue signal sequence and the first 199 amino acids of the N-terminus of the mature human BPI, as set out in
Biologically active variants of BPI (BPI variants) include but are not limited to recombinant hybrid fusion proteins, comprising BPI holoprotein or a biologically active fragment thereof and at least a portion of at least one other polypeptide, and dimeric forms of BPI variants. Examples of such hybrid fusion proteins and dimeric forms are described by Theofan et al. in co-owned, copending U.S. patent application Ser. No. 07/885,911, and a continuation-in-part application thereof U.S. patent application Ser. No. 08/064,693 filed May 19, 1993 which are incorporated herein by reference in their entirety and include hybrid fusion proteins comprising, at the amino-terminal end, a BPI protein or a biologically active fragment thereof and, at the carboxy-terminal end, at least one constant domain of an immunoglobulin heavy chain or allelic variant thereof.
Biologically active analogs of BPI (BPI analogs) include but are not limited to BPI protein products wherein one or more amino acid residue has been replaced by a different amino acid. For example, co-owned, copending U.S. patent application Ser. No. 08/013,801 (Theofan et al., “Stable Bactericidal/Permeability-Increasing Protein Products and Pharmaceutical Compositions Containing the Same,” filed Feb. 2, 1993), the disclosure of which is incorporated herein by reference, discloses polypeptide analogs of BPI and BPI fragments wherein a cysteine residue is replaced by a different amino acid. A preferred BPI protein product described by this application is the expression product of DNA encoding from amino acid 1 to approximately 193 or 199 of the N-terminal amino acids of BPI holoprotein, but wherein the cysteine at residue number 132 is substituted with alanine and is designated rBPI21Δcys or rBPI21.
Other BPI protein products useful according to the methods of the invention are peptides derived from or based on BPI produced by recombinant or synthetic means (BPI-derived peptides), such as those described in co-owned and copending U.S. patent application Ser. No. 08/209,762, filed Mar. 11, 1994, which is a continuation-in-part of U.S. patent application Ser. No. 08/183,222, filed Jan. 14, 1994, which is a continuation-in-part of U.S. patent application Ser. No. 08/093,202 filed Jul. 15, 1993), which is a continuation-in-part of U.S. patent application Ser. No. 08/030,644 filed Mar. 12, 1993, the disclosures of which are hereby incorporated by reference. Other useful BPI protein products include peptides based on or derived from BPI which are described in co-owned and co-pending U.S. patent application Ser. No. 08/274,299 filed Jul. 11, 1994, by Horwitz et al. and U.S. patent application Ser. No. 08/273,540, filed Jul. 11, 1994, by Little et al.
Presently preferred BPI protein products include recombinantly-produced N-terminal fragments of BPI, especially those having a molecular weight of approximately between 21 to 25 kD such as rBPI21 or rBPI23, dimeric forms of these N-terminal fragments. Additionally, preferred BPI protein products include rBPI50 and BPI-derived peptides.
The administration of BPI protein products is preferably accomplished with a pharmaceutical composition comprising a BPI protein product and a pharmaceutically acceptable diluent, adjuvant, or carrier. The BPI protein product may be administered without or in conjunction with known surfactants, other chemotherapeutic agents. A preferred pharmaceutical composition containing BPI protein products comprises the BPI protein product at a concentration of 1 mg/ml in citrate buffered saline (5 or 20 mM citrate, 150 mM NaCl, pH 5.0) comprising 0.1% by weight of poloxamer 188 (Pluronic F-68, BASF Wyandotte, Parsippany, N.J.) and 0.002% by weight of polysorbate 80 (Tween 80, ICI Americas Inc., Wilmington, Del.). Another preferred pharmaceutical composition containing BPI protein products comprises the BPI protein product at a concentration of 2 mg/ml in 5 mM citrate, 150 mM NaCl, 0.2% poloxamer 188 and 0.002% polysorbate 80. Such preferred combinations are described in co-owned, co-pending, U.S. patent application Ser. No. 08/190,869 filed Feb. 2, 1994 (McGregor et al., “Improved Pharmaceutical Compositions”), and U.S. patent application Ser. No. 08/012,360 filed Feb. 2, 1993 (McGregor et al., “Improved Pharmaceutical Composition”), the disclosures of which are incorporated herein by reference.
The BPI protein product can be administered by any known method, such as orally, systemically (such as by intravenous, intramuscular or other injection), or as an aerosol. Medicaments can be prepared for oral administration or by injection or other parenteral methods and preferably include conventional pharmaceutically acceptable carriers and adjuvents as would be known to those of skill in the art. The medicaments may be in the form of a unit dose in solid, semi-solid and liquid dosage forms such as tablets, pills, powders, liquid solutions or suspensions, and injectable and infusible solutions. Effective dosage ranges from about 100 μg/kg to about 10 mg/kg of body weight are contemplated. Intravenous administration is a preferred method for treatment of leprosy.
It is contemplated that aerosol administration to the lungs will be a preferred method for treating other Mycobacterial infections, such as tuberculosis. Such aerosol formulations would be manufactured by means that are known in the art, and administered by metered-dose inhaler, updraft nebulization, or other means known in the art.
An aspect of the present invention is to provide methods of treating a subject suffering from any of the physiological effects of Mycobacterial LAM. As described above, the physiological effects of LAM depend on a number of factors, including the source and concentration of the LAM, and the length of time to which host cells are exposed to LAM. Example 3, infra, demonstrates that 20-100 μg/ml of nonviable, desiccated M. tuberculosis added to whole blood will stimulate TNF production by the monocytes in the blood. Other studies described above have shown that 50-100 μg/ml of LAM will down-regulate macrophage functions and expression (TNF, and the like) and prevent macrophage activation, said methods comprise administering a BPI protein product to the subject. Methods are provided for treating a subject suffering from the effects of increased cytokine production caused by the physiological presence of LAM. Methods are also provided for treating a subject suffering from LAM-induced inhibition of macrophage activation, and the effects thereof. Methods and formulations by which a BPI protein product may be administered, including preferred methods and formulations, are the same as those set forth above for the treatment of Mycobacterial infection.
Because of the harmful physiological effects that Mycobacterial LAM can have on a subject, even in the absence of viable Mycobacteria, methods are provided in the present invention by which a fluid containing LAM may be decontaminated prior to administration of the fluid into a subject. Such methods comprise contacting the fluid with a BPI protein product prior to administration, under conditions such that LAM forms a complex with the BPI protein product, thereby decontaminating the fluid. By way of nonlimiting examples, such methods may be applied to fluids such as blood, plasma, blood serum, bone marrow, isotonic solutions, pharmaceutical agents, or cell culture reagents.
BPI protein product is thought to interact with a variety of host defense elements present in whole blood or serum, including complement and LBP, and other cells and components of the immune system. Such interactions might result in potentiating and/or synergizing the anti-microbial activities. Because of these interactions, BPI protein products are expected to exert even greater activity in vivo than in vitro. Thus, while in vitro tests are predictive of in vivo utility, absence of activity in vitro does not necessarily indicate absence of activity in vivo. For example, BPI has been observed to display a greater bactericidal effect on certain gram-negative bacteria in whole blood or plasma assays than in assays using conventional media. [Weiss et al., J. Clin. Invest. 90: 1122-1130 (1992)]. This may be because conventional in vitro systems lack the blood elements that facilitate or potentiate BPI's function in vivo, or because conventional media designed to maximize bacterial growth contain higher than physiological concentrations of magnesium and calcium, inhibitors of BPI protein product antibacterial activity.
Therapeutic effectiveness is based on a successful clinical outcome, and does not require that an anti-mycobacterial agent or agents kill 100% of the orgainism involved in the infection. Frequently, reducing organism load by one log (factor of 10) permits the host's own defenses to control the infection. In addition, augmenting an early anti-mycobacterial effect can be particularly important in addition to any long-term anti-mycobacterial effect. These early events are a significant and critical part of therapeutic success, because they allow time for host defense mechanisms to activate.
It is also contemplated that the BPI protein product be administered with other products that potentiate the anti-mycobacterial activity of BPI protein products. For example, serum complement potentiates the gram-negative bactericidal activity of BPI protein products; the combination of BPI protein product and serum complement provides synergistic bactericidal/growth inhibitory effects. See, e.g., Ooi et al. J. Biol. Chem., 265: 15956 (1990) and Levy et al. J. Biol. Chem., 268: 6038-6083 (1993) which address naturally occurring 15 kD proteins potentiating BPI antibacterial activity. See also co-owned, co-pending U.S. patent application Ser. No. 08/093,201 filed Jul. 14, 1993, and continuation-in-part, U.S. patent application Ser. No. 08/274,303 filed Jul. 11, 1994 which describes methods for potentiating gram-negative bactericidal activity of BPI protein products by administering lipopolysaccharide binding protein (LBP) and LBP protein products. The disclosures of these applications are incorporated by reference herein. LBP protein derivatives and derivative hybrids which lack CD-14 immunostimulatory properties are described in co-owned, co-pending U.S. patent application Ser. No. 08/261,660, filed Jun. 17, 1994 as a continuation-in-part of U.S. patent application Ser. No. 08/079,510, filed Jun. 17, 1993, the disclosures of which are incorporated by reference herein.
An aspect of this invention includes the use of a composition comprising a BPI protein product for the manufacture of a medicament for the therapeutic application of treating any of the aforementioned conditions or diseases from which a subject suffers. The medicament may include, in addition to a BPI protein product, other chemotherapeutic agents such as known anti-mycobacterial antibiotics or surfactants. The medicament may additionally or alternatively include one or more additional pharmaceutically acceptable components, such as diluents, adjuvants, or carriers.
An aspect of the present invention is the ability to provide more effective treatment of Mycobacterial infection by virtue of the synergistic increase in or potentiation of the anti-bacterial activities of an anti-Mycobacterial antibiotic or BPI protein product. As previously noted, anti-Mycobacterial antibiotic therapy currently involves administration of one or more (and frequently three or more) antibiotics such as isoniazid, rifampin, ethambutol, p-aminosalicylic acid, pyrazinamide, streptomycin, capreomycin, cycloserine, ethionamide, kanamycin, amikacin, amithiozone, rifabutin, clofazimine, arithromycin, clarithromycin, ciprofloxacin and ofloxacin. Unlike some therapeutic agents, BPI protein product is easily administered and produces no inflammatory reaction. An aspect of the present invention is the ability to treat Mycobacterial organisms that are normally resistant to one or more antibiotics. A further aspect is the ability to use lower concentrations of relatively toxic or expensive antibiotics such as rifampin. Because the use of some antibiotics is limited by their systemic toxicity or prohibitive cost, lowering the concentration of antibiotic required for therapeutic effectiveness reduces toxicity and/or cost of treatment, and thus allows wider use of the antibiotic. The present invention may also provide quality of life benefits due to, e.g., decreased duration of therapy, reduced stay in intensive care units or overall in the hospital, with the concomitant reduced risk of serious nosocomial (hospital-acquired) infections.
The invention further provides pharmaceutical compositions for treatment of Mycobacterial infection and the sequelae thereof comprising the combination of a BPI protein product and an antibiotic which is present in an amount effective to have synergistic or potentiating bactericidal/bacteriostatic properties, including increased susceptibility or reversal of resistance. The pharmaceutical composition can comprise a pharmaceutically-acceptable diluent, adjuvant or carrier.
Methods of the present invention are more fully illustrated by the nonlimiting examples which follow. Example 1 address BPI protein products binding to a species of Mycobacterium, M. tuberculosis. Example 2 address prospective use of BPI protein products in binding purified LAM of Mycobacteria. Examples 3 and 4 describe attempts to reverse Mycobacteria-induced cytokine production in whole human blood. Example 5 addresses use of BPI protein products in combination with anti-mycobacterial antibiotics to inhibit M. tuberculosis growth. Remaining Examples 6-13 address prospective in vitro and in vivo use of BPI protein products according to methods of this invention. The models described in those examples and/or other models known in the art are used to predict the efficacy and the optimal BPI protein product formulations of the methods of invention.EXAMPLE 1
An enzyme linked immunosorbent assay (ELISA) was conducted to determine binding of a BPI protein product to M. tuberculosis. Specifically, non-viable, desiccated M. tuberculosis H37 RA (Difco, Detroit, Mich.) was suspended in DPBS (25 μg/ml) and used to coat microtiter wells overnight at 37° C. Wells were also coated with either 25 μg/ml Lipid A (E. coli J5 mutant, RIBI, Hamilton, Mont.) or 500 μl DPBS to demonstrate the functionality and specificity of rBPI23. After washing (3× with DPBS+0.05% Tween 20), the plates were blocked for 1 hr. at room temperature with 200 μl/well of DPBS+1% non-fat milk. After washing as above, 50 μl solutions of either various concentrations of rBPI23 (in DPBS containing 0.05% Tween 20) or DPBS (negative control) were added to the wells, which were then incubated for 1 hr. at 37° C. The wells were again washed as above, and the amount of rBPI23 bound to the wells was determined using an anti-rBPI23 mouse monoclonal antibody (designated αBPI MAb-24) and an enzyme conjugated anti-murine IgG antibody (HRP-Ab, Zymed #61-0120, San Francisco, Calif.). To each well 100 μl of αBPI MAb-2-4 was added (100 ng/ml in DPBS+0.05% Tween 20), and the plates were incubated 1 hr. at 37° C. After washing as above, 100 μl of HRP-Ab was added (1:1000 in DPBS+0.05% Tween 20) to each well and the plates were again incubated 1 hr. at 37° C. After washing the plates as above, 100 μl substrate in 0.1M citrate plus 1:50 ABTS (20 mg/ml stock) and 1:1000H2O2 was added to each well. The plates were incubated 10-30 min. at room temperature, and absorbance readings were taken at 405 nm (OD 405).
The results of the experiment are represented graphically in
This experiment demonstrated that rBPI23 binds specifically to non-viable desiccated M. tuberculosis. The functionality of the rBPI23 used in these experiments was confirmed by the results of the Lipid A (positive control) binding assay, and the specificity of the experiments was confirmed by the lack of binding to the negative control samples.EXAMPLE 2
In this example, an ELISA Assay is conducted to determine binding of a BPI protein product to the lipoarabinomannan portion of Mycobacteria. The binding activity of BPI protein product (e.g., rBPI23) to LAM is demonstrated as described in the previous example, except LAM purified from a species of Mycobacterium, (e.g., M. tuberculosis or M. leprae) is substituted for the nonviable M. tuberculosis used to coat the ELISA plates in that example. Purified LAM is isolated as described by Hunter et al., J. Biol. Chew., 261: 12345-12351 (1986). Specific binding of biologically active BPI protein product is demonstrated by comparison of the OD 405 readings from the LAM coated wells with positive and negative controls.EXAMPLE 3
The following experiment was conducted to determine the effect of a BPI protein product, rBPI23, on Mycobacteria-induced cytokine production in whole human blood. Whole human blood from healthy volunteers was collected into Vacutainer tubes (ACD, Beckton Dickinson, Rutherford, N.J.). Aliquots of blood (225 μl) were mixed with either rBPI23 (10 μg/ml final) or the protein thaumatin (10 μg/ml final in 5 ml) as a negative control. RPMI medium (20 μl) was added to each sample. Varying dilutions (0-8 ng/ml) of either E. coli O113 LPS (Ribi, Hamilton Mich.) or of non-viable, desiccated M. tuberculosis H37 RA (0-100 μg/ml) (Difco, Detroit Mich.) were added to the samples, which were then incubated at 37 C for 6 hours. The reactions were stopped by the addition of 750 μl of RPMI medium, the samples were centrifuged at 500 g for 7 min, and stored at −20° C. until analyzed. The supernatant was assayed for cytokine (TNF) levels based on a standard curve, according to the manufacturers' recommendation (Biokine ELISA test, T Cell Sciences, Cambridge, Mass.).
The assay results revealed that rBPI23 at 10 μg/ml had no inhibitory effect on M. tuberculosis-induced TNF release at the concentration (20-100 μg/ml) of M. tuberculosis added to the blood samples. The same concentration of rBPI23 eliminated LPS-induced TNF release at the LPS concentrations tested (2-8 ng/ml). The lack of inhibitory effect on cytokine induction by M. tuberculosis may be the result of use of sub-optimal dosage levels. Alternatively, some component of the Mycobacterial cell wall other than the LAM bound by rBPI23 may be responsible for inducing cytokine production at the Mycobacterium concentrations tested.EXAMPLE 4
In this example, multiple additional assays were conducted to assess the inhibitory effect of BPI protein products on mycobacterial (M. tuberculosis or M. smegmatis) induced production of tumor necrosis factor (TNF) by monocytes/macrophages present in whole human blood. Briefly summarized, live or heat killed mycobacteria at varying concentrations was added to whole blood and incubated with either a fixed amount BPI protein product or acetate buffer negative control solution. After incubation, the content of TNF present was assessed by standard means. The TNF content of BPI protein product treated samples was then compared to the TNF content of buffer control samples to determine the relative inhibitory effect of the BPI protein product tested. Whole blood samples were obtained from healthy human volunteers and aliquoted as in Example 3. To each tube containing 225 μl of whole blood was added from 0 to 1×107 live or heat killed mycobacteria. Depending on whether one or two BPI protein products were to be tested, four or six tubes were prepared at each concentration of bacteria, after which the tubes were incubated at 37° C. for 15 minutes. To two of the tubes at each bacterial concentration was added either a selected BPI protein product at a final concentration of 4 μg/ml or acetate buffer (as a negative control), after which is tubes were further incubated at 37° C. for 5 to 6 hours. Thereafter 750 μl of RPMI 1640 was added to each sample and the samples were centrifuged at 17,000 rpm (500 g?) for 6 minutes. Supernatants were stored at −70° C. until thawed immediately prior to testing for TNF content using the Biokine ELISA test kit as in Example 3.
In a first series of assays, heat-killed M. tuberculosis (strain H37Ra) was employed as the TNF stimulating organism. In a first test on whole blood, no substantial increased in TNF levels was observed until bacteria were added at a concentration of 1×106 organisms and the presence of rBPI23 in the samples resulted in an approximately 70% inhibition of TNF production. In a second test involving two separate whole blood assays, inhibitory effects of both rBPI23 and BPI holoprotein were assessed. Substantial increases in TNF concentration over basal levels (no microorganisms added) were observed commencing at microorganism concentrations of 3×105 up through 1×107. Overall, inhibition of TNF production by 20% or greater was observed when rBPI23 was added at all such organism levels. Lesser degrees of inhibition were noted for the BPI holoprotein (with no inhibition at all noted in one duplicate test at the highest concentration of organisms). The lesser effects of the holoprotein in these assays are likely attributable to the lower molar concentration employed. A third M. tuberculosis test was performed on whole blood drawn from four different volunteers, using rBPI23 as the test compound. Expectedly, the level of inhibition of TNF formation by the uniform dose of BPI protein product varied from subject to subject. With the exception of one subject's blood samples (wherein inhibition was observed only at intermediate microorganism concentration of 1×106 and not at all at concentrations of 1×107), the BPI protein product provided for at least about 10% and up to about 50% TNF inhibition, with higher inhibitory levels being observed at higher microorganism concentrations. A fourth test involving M. tuberculosis was carried out using rBPI23 at 4 μg/ml and 8 μg/ml concentrations. The BPI protein product was again observed to inhibit TNF at the 4 μg/ml level, with the greatest effects being observed at microorganism concentrations of 3×106. Doubling the concentration of test compound to 8 μg/ml did not enhance, and in fact somewhat diminished, inhibitory effects observed.
In a second series of assays, heat killed M. smegmatis was employed to stimulate TNF production in whole blood. In a first test, whole blood from eight different patients was employed and was subjected to contact with concentrations of 0, 0.5×105, 1×105, 1×106 and 1×107 organisms.
The above assay results demonstrate in vitro effectiveness of BPI protein products in inhibiting induction of tumor necrosis factor by mycobacterial species and are predictive of in vivo efficacy in human patients.EXAMPLE 5
In this example, rBPI23 at varying concentrations was assessed for its growth inhibitory effect on M. tuberculosis treated with varying concentrations of the anti-Mycobacterial antibiotics isoniazid (INH) and rifampin (RMP). Briefly summarized, pure cultures of M. tuberculosis (MTB) were incubated for 24 hours with varying concentrations of rBPI23 and antibiotic. Cultures were added to Bactec® bottles (Johnston Laboratories, Cockeysville, Md.) containing 14C labeled nutrients and daily “growth index” values were determined accordingly to the supplier's instructions on the basis of 14CO2 evolved from the medium. In separate assays, concentrations of rBPI23 of 0, 3.9, 15.6, 62.5, 250 and 1000 μg/ml were combined with INH at levels of 0, 0.006, 0.012, 0.025 and 0.05 μg/ml or RMP levels of 0, 0.12, 0.25, 0.5 and 1.0 μg/ml. Growth index values were assessed daily starting the second day after inoculation into the vials through to the eighteenth day. In the INH assay, no BPI protein product was added, growth index values characteristically gradually increased over time and as a function of the dosage of antibiotic employed (increases generally began earlier and rose more steeply at lower doses than at higher doses). Addition of rBPI23 had variable effects in enhancing or diminishing antibiotic effects on growth index values, depending on the concentration employed. An intermediate dose (62.5 μg/ml) of BPI protein product consistently tended to reduce growth index values at all doses of INH tested and thus operated to enhance INH growth inhibitory effects. Similar but less pronounced enhancement effects were observed for the 15.6 μg/ml rBPI23 dose. Lower (0 and 3.9 μg/ml) and higher (250 and 1000 μg/ml) doses of the BPI protein product generally diminished the antibiotic effects of INH, with the highest rBPI23 dose invariably functioning to increasing “swamp out” INH effects on growth index toward the middle of the test period. At later times in the test period, however, the highest doses of BPI protein product appeared to suppress and actually reverse the above-noted characteristic increases in growth index over time. In combinative assay with RMP, rBPI23 had no discernible enhancing effect at the highest doses of the antibiotic 0.5 and 1.0 μg/ml where there was essentially no increase in growth index throughout the entire test period. At lesser concentrations pf RMP, there tended to be a dose-dependent enhancement effect of the BPI protein product, with the greatest degree of enhancement occurring at the highest doses of rBPI23 and no evidence of the “swamp out” effects observed for combinations with INH intermediate times within the test period.
The results set out above establish utility of BPI protein product concurrently filed in enhancing the growth inhibitory effects of anti-mycobacterial antitiotics.EXAMPLE 6
The following experiment is conducted to determine the in vitro inhibitory effect of a BPI protein product on the growth of a Mycobacterium species, Mycobacterium tuberculosis (MTB). The procedure can be performed with other cultivable Mycobacterial species and employs concentrations of a BPI protein product that would be readily generated in human serum by ordinary modes of oral or parenteral administration and/or readily delivered to lung surface by aerosol administration. The effects of the BPI protein product can be evaluated with and without non-ionic surfactants, and/or standard antibiotics.
Log phase cultures of antibiotic-sensitive and antibiotic-resistant MTB are incubated in either 7H11 broth medium or whole human blood, to which the following is added: (a) nothing; (b) surfactant; (c) standard MTB antibiotic; (d) antibiotic plus surfactant. Cultures are incubated with varying concentrations of, e.g., rBPI23. Duplicate cultures grown in each medium are also left untreated by rBPI23 as a negative control. The organisms are placed in Bactec® bottles (Johnston Laboratories, Cockeysville, Md.) containing 14C labeled nutrients. rBPI23 challenged M. tuberculosis growth is determined by measuring the elution of 14CO2 from the medium, compared to the appropriate negative control. The absence of the formation 14CO2 by the treated cultures is indicative of the inhibitory affects of rBPI23 to MTB. Differential amounts of 14CO2 formed in the absence or presence of standard MTB antibiotics and/or surfactants is indicative of the synergistic or additive effect that a BPI protein product has when used conjunctively with such agents. By comparing the results of this experiment performed with varying concentrations of the BPI protein product, the effective concentration of the BPI protein product is optimized. Radiometric assays to test the susceptibility of Mycobacterial species to drugs have been described previously. See McClatchy (cited supra) and references therein.EXAMPLE 7
The following experiment is conducted to determine the in vitro effects of a BPI protein product (rBPI23) in an M. leprae model. A palmitic acid oxidation assay is used to measure the “viability” of the uncultivable leprosy bacillus adhered to filter paper and “grown” in a 14C-palmitic acid-containing medium. In this method 14CO2 evolved from the metabolism by M. leprae of 14C-palmitic acid is trapped on filter paper moistened with NaOH and radioactivity is determined with a liquid scintillation counter. Susceptibility to BPI protein product formulations is determined by differences in radioactivity for M. leprae tested with such formulations and treated control cultures.EXAMPLE 8
The following experiment, which is a variation of an assay conducted by Mittal et al., J. Clin. Microbiol., 17 (4): 704-707 (1983), is conducted to determine the in vitro inhibitory effect of BPI protein product on the growth of Mycobacterium leprae. The effects of different concentrations of BPI protein product on M. leprae are evaluated with and without non-ionic surfactants, and/or standard antibiotics. The procedures as described by Mittal et al. are outlined below.
Skin biopsy specimens from lepromatous patients are homogenized and are used to inoculate suspensions of mouse peritoneal macrophages cultured in RPMI 1640 (GIBCO Biocult, Irvine, Scotland) enriched with 30% fetal calf serum. After incubating 18 hours, fresh media containing [methyl-3H]-thymidine (Amersham International Ltd., Arlington Heights, Ill.) is added and the cultures are incubated for 14 days. The procedure of Mittal et al. is varied by testing the effect of different concentrations of BPI protein product with or without surfactants and/or antibiotics on 3H-thymidine incorporation. Macrophages containing phagocytosed viable M. leprae will incorporate 3H-thymidine at a 2 to 10-fold higher rate than control cultures containing heat killed M. leprae. Greater than 50% inhibition of 3H-thymidine-incorporation is indicative of bactericidal efficacy of the test product.EXAMPLE 9
An experiment is conducted to determine the in vivo effect that a BPI protein product will have on M. tuberculosis species. The model employed is a variation of that used by Lalande et al., Antimicrobial Agents and Chemotherapy, 37 (3): 407-413 (1993), to assess the efficacy of antimicrobial agents against M. tuberculosis. Mice inoculated intravenously with M. tuberculosis are treated with various BPI protein product doses alone or in combination with surfactants and/or antibiotics. The efficacy of such treatment regiments is analyzed as described.EXAMPLE 10
The following experiment is conducted to determine the effect that a BPI protein product will have on M. leprae in vivo. The model to be used is a variation of that developed by Shepard to study the effect of compounds on the growth of M. leprae in the footpads of infected mice. Shepard et al., Proc. Soc. Exp. Biol. Med., 109: 636-638 (1962); Shepard, J. Exp. Med. 112: 445-454 (1960). Briefly, leprosy bacilli are inoculated into foot-pads of mice, which are subsequently treated with different amounts of test compound with or without known antibiotics and/or surfactants. Untreated infected mice are used as a control. Mice from each treatment regimen are sacrificed at monthly intervals, and sections cut from the infected foot. The presence of an area containing acid-fast bacteria can be observed microscopically and/or the number of such bacteria can be counted. See Shepard and McRae, Int. J. Lepr., 36: 78-82. Differences between M. leprae bacteria levels observed in treated versus control mice is indicative of the bacteriostatic or bactericidal efficacy of a given BPI treatment regimen. The metabolic status of isolated M. leprae may also be measured. Franzblau and Hastings, Antimicrobial Agnes and Chewmotherapy, 31 (5): 780-783 (1987).EXAMPLE 11
The following experiments are designed to demonstrate that BPI protein product is able to inhibit the ability of low concentration of LAM to induce cytokines, yet reverse the unresponsive state that attends higher concentrations of LAM. Increasing concentrations of LAM are pretreated with BPI protein product at varying concentrations. These complexes are applied to peritoneal macrophages from normal and Mycobacterium species infected mice. TNF production by treated cells will be assessed.EXAMPLE 12
A variation of the armadillo model developed by Kirchheimer et al., Int. J. Lepr., 39: 693-702 (1971); Id., 40: 229 (1972), is employed to study the in vivo effect of BPI protein product test compositions on the growth of M. leprae in infected armadillos. Briefly, leprosy bacilli are inoculated into armadillos, which are subsequently treated with different amounts of a test composition. The test compositions will comprise a BPI protein product, e.g. rBPI23, with or without known antibiotics and/or surfactants. Untreated infected specimens are used as a control. Armadillos from each treatment regimen are examined and biopsy specimens analyzed by procedures known in the art. M. leprae isolated from armadillos is assayed for metabolic activity. Differences between the appearance of lesions, differences in M. leprae bacterial concentrations, and differences in the metabolic activity of M. leprae isolates in treated versus control specimens are indicative of the bacteriostatic or bactericidal efficacy of a given BPI treatment regimen.EXAMPLE 13
The following experiment is conducted to determine the level of decontamination of a fluid containing LAM that can be achieved by treatment with a BPI protein product. Whole human blood, plasma, blood serum or the like is passed through a column containing a matrix, to which a BPI protein product is bound. Such matrix may be constructed by any means known to those skilled in the art. LAM in the fluid complexes with the BPI protein product affixed to the matrix as the fluid is passed through the column. The absence of LAM in the fluid eluted from the column demonstrates the effectiveness of a BPI protein product at decontaminating a fluid containing LAM.
Alternatively, monoclonal antibodies with binding specificity for a BPI protein product, such as the antibodies employed in Example 1, are affixed to the matrix. A sufficient amount of a BPI protein product is added to the mixture to bind any LAM present in the fluid. The fluid is purified by passing it through the column. The αBPI antibodies affixed to the column bind the LAM/BPI protein product complex in the fluid, and the fluid eluted from the column is analyzed for the presence or absence of LAM contamination.
Numerous modifications and variations in the practice of the invention are expected to occur to those skilled in the art upon consideration of the foregoing description of the presently preferred embodiments thereof. For example, while the above illustrative examples principally address studies predictive of antibacterial effects in the context M. tuberculosis and M. leprae, model studies of infection with, e.g., M. avium [see, e.g., Brown et al., Antimicrob. Agents and Therapy, 37 (3): 398-402 (1993)] are also expected to reveal effectiveness of BPI protein product therapies. As another example, preliminary experimental data indicates that BPI protein products alone and/or in combination with cytokines such as gamma interferon (and in combination with antibiotics as well) can enhance the rate at which human monocytes phagocytize Mycobacterial organisms. Combinative therapies involving administration of cytokines along with BPI protein products (and antibiotics) are thus within the scope of the invention). Consequently, the only limitations which should be placed upon the scope of the present invention are those which appear in the appended claims.
10. A method of treating a subject suffering from the adverse physiological effects of the presence of lipoarabinomannan in circulation, the method comprising administering to the subject a pharmaceutical composition comprising a BPI protein product selected from the group consisting of amino-terminal fragments of BPI holoprotein having a molecular weight of 21-25 kD by SDS-PAGE and dimeric forms thereof, rBPI21, rBPI23, rBPI and BPI-derived peptides, or fusion protein comprising said BPI protein product, and a pharmaceutically acceptable diluent, adjuvant, or carrier.
11. The method of claim 10 wherein the adverse physiological effects comprise compromised immune response to microbes or tumor cells due to lipoarabinomannan-induced inhibition of macrophage activation by T-cell lymphokines.
12. The method of claim 10 wherein the adverse physiological effects comprise increased production of a cytokine by the subject.
13. The method of claim 10 wherein the composition is administered orally.
14. The method of claim 10 wherein the composition is administered intravenously.
15. The method of claim 10 wherein the composition is administered as an aerosol.
16. The method of claim 10 wherein the BPI protein product is a 21-25 kD amino-terminal fragment of Bactericidal/permeability-increasing protein.
17. The method of claim 10, wherein the composition further comprises a surfactant.
Filed: Sep 8, 2003
Publication Date: Jun 2, 2005
Applicant: XOMA CORPORATION (Berkeley, CA)
Inventor: Lewis Lambert (Fremont, CA)
Application Number: 10/658,112