Proteomic analysis of biological fluids
The invention concerns the identification of proteomes of biological fluids and their use in determining the state of maternal/fetal conditions, including maternal conditions of fetal origin, chromosomal aneuploidies, and fetal diseases associated with fetal growth and maturation. In particular, the invention concerns the identification of the proteome of amniotic fluid (multiple proteins representing the composition of amniotic fluid) and the correlation of characteristic changes in the normal proteome with various pathologic maternal/fetal conditions, such as intra-amniotic infection, or chromosomal defects.
This application is a continuation of U.S. application Ser. No. 10/400,005, filed Mar. 25, 2003.
BACKGROUND OF THE INVENTION1. Field of the Invention
The invention concerns the identification of proteomes of biological fluids and their use in determining the state of maternal/fetal conditions, including maternal conditions of fetal origin, chromosomal aneuploidies, and fetal diseases associated with fetal growth and maturation. In particular, the invention concerns the identification of the proteome of amniotic fluid (multiple proteins representing the composition of amniotic fluid) and the correlation of characteristic changes in the normal proteome with various pathologic maternal/fetal conditions, such as intra-amniotic infection, or chromosomal defects.
2. Description of the Related Art
Proteomics
The large-scale analysis of protein expression patterns is emerging as an important and necessary complement to current DNA cloning and gene profiling approaches (Pandey and Mann, Nature 405:837-46 (2000)). DNA sequence information is helpful in deducing some structural and potential protein modifications based on homology methods, but it does not provide information on regulation of protein function through post-translational modifications, proteolysis or compartmentalization.
Traditional gel-based methods, such as one- and two-dimensional gel electrophoresis are useful for small-scale protein detection (<1,000 proteins), but these require large sample quantity (Lilley K S, Razzaq A, Dupree P: Two-dimensional gel electrophoresis: recent advances in sample preparation, detection and quantitation. Curr Opin Chem Biol. 6(1):46-50, 2002). Approaches to overcome this limitation include matrix-assisted or surface-enhanced laser desorption/ionization (MALDI or SELDI) time-of-flight mass spectrometers that accurately generate profiles showing the masses of proteins in a sample. These patterns or profiles can be used to identify and monitor various diseases. The second level of identification comes from coupling peptide mapping to tandem mass spectrometry to generate amino acid sequence information from peptide fragments. This can, for example, be achieved by coupling the MALDI/SELDI or ESI to quadrupole time-of-flight MS (Qq-TOF MS). The latter method can also be used for quantification of specific peptides (ICAT technology).
Diagnosis of Pathologic Maternal/Fetal Conditions
There are numerous pathologic maternal and fetal conditions, such as intra-amniotic infection (IAI), preeclampsia, preterm delivery and labor, and chromosomal aneuploidies, that may develop during pregnancy and compromise the well-being or, in some instances, threaten the life of the mother and/or the fetus or newborn. Early diagnosis of such conditions is critical to allow timely treatment and intervention. Unfortunately, early diagnosis for most of these conditions is difficult because the clinical signs and symptoms occur late, and are often non-specific and inconsistent. For example, the clinical symptoms of IAI typically include maternal fever and leukocytosis, but these symptoms often occur later and are neither sensitive nor specific. Thus, Gravett et al., Am. J. Obstet. Gynecol. 171:1660-7 (1994), utilizing a non-human primate model, demonstrated that following experimental intra-amniotic infection with Group B streptococcus, fever and leukocytosis are present only 50% of the time at the onset of infection-induced preterm labor, which occurs 28 to 40 hours after experimental infection. Therefore, to avoid a delay in diagnosis, a high index of suspicion and the appropriate use of adjunctive laboratory tests, are warranted. The clinical criteria commonly used to diagnose IAI include maternal fever (≧37.8° C.), along with two or more of the following: maternal leukocytosis (≧15,000/mm3), maternal or fetal tachycardia, uterine tenderness, or foul-smelling amniotic fluid.
Because of the inconsistency of clinical features, other adjunctive laboratory tests have been utilized to aid in the diagnosis of IAI. These include: measurement of maternal C-reactive protein, direct examination of amniotic fluid for leukocytes or bacteria on Gram stain, amniotic fluid culture, measurement of amniotic fluid glucose concentrations, detection of amniotic fluid leukocyte esterase, detection of bacterial organic acids by gas-liquid chromatography, measurements of various amniotic fluid or vaginal cytokines (e.g., interleukins 2, 4, 6, granulocyte colony-stimulating factor, and tumor necrosis factor-α), matrix metalloproteinase-9, lactoferrin, and assessment of fetal activity (biophysical profile) by ultrasonography. Measurement of cytokines or other biochemical factors is expensive, generally not clinically available, and is primarily a research tool. Further, the testing efficiency of these tests has not been consistently better than more readily available traditional tests such as amniotic fluid Gram stain and culture, amniotic fluid glucose concentrations, and detection of amniotic fluid leukocyte esterase. The efficiency of these tests has been previously extensively reviewed. (Ohlsson, A. and Wang, E.: An analysis of antenatal tests to detect infection at preterm rupture of the membranes. American Journal of Obstetrics and Gynecology 162:809, 1990). Although all have reasonable sensitivity, specificity, and predictive value none are sufficiently sensitive or specific to be utilized independently of clinical features in the diagnosis of IAI.
Accordingly, there is a great need for new approaches that allow early and accurate diagnosis of IAI and other pathologic maternal/fetal conditions.
It is particularly desirable to develop new, efficient and reliable non-invasive methods for the diagnosis of chromosomal aneuploidies. At present the definitive diagnosis of chromosomal aneuploidies following maternal serum screening and ultrasound requires a mid-trimester genetic amniocentesis. This is an invasive procedure associated with a 0.5% risk of loss of the pregnancy. Further, chromosomal analysis of amniotic fluid cells is a labor-intensive and time-consuming procedure, taking up to 2 weeks. Reliable tests are therefore necessary to improve the detection of chromosomal aneuploidies from maternal serum, or other biological fluids, reduce the unacceptably high false positive rate of maternal screening, and increase the speed and efficiency of diagnosis from amniotic fluid following amniocentesis. Other pathologic aneuploidic conditions, such as Klinefelter syndrome and Turner syndrome, may be entirely missed by screening with ultrasonography or conventional maternal serum screening.
SUMMARY OF THE INVENTIONThe present invention provides non-invasive and sensitive methods for the early diagnosis, prognosis, and monitoring of pathologic fetal/maternal conditions, by proteomic analysis of biological fluids.
The present invention further provides proteomic profiles of biological fluids, such as amniotic fluid and maternal serum, which enable the diagnosis, prognosis, and monitoring of various pathologic fetal/maternal conditions, including, without limitation, intra-amniotic infection (IAI), chromosomal aneuploidies, and fetal diseases associated with fetal growth and maturation. In particular, the present invention provides normal and pathologic proteomic profiles for IAI and chromosomal aneuploidies. The determination of the normal proteomic profile is of great importance, since it enables the elimination of the fetal/maternal condition in question (negative diagnosis), which eliminates the need to subject the patient to unnecessary and potentially dangerous treatment or intervention.
The present invention further provides specific biomarkers for the presence and state of IAI and chromosomal aneuploidies, which are differentially expressed in biological fluids, such as amniotic fluid or maternal serum, when such pathologic conditions are present.
In one aspect, the invention concerns a method for determining the state of a maternal or fetal condition, comprising comparing the proteomic profile of a test sample of a biological fluid obtained from a mammalian subject with the proteomic profile of a normal sample, or a reference proteomic profile comprising at least one unique expression signature characteristic of such condition.
In an embodiment of this method, the mammalian subject is a pregnant female, preferably primate or human.
In another embodiment, the maternal condition is selected from the group consisting of intrauterine infection, preeclampsia, and preterm labor.
In a further embodiment, the fetal condition is selected from the group consisting of chromosomal aneuploidies, congenital malformation, gestational age and fetal maturity, where the chromosomal aneuploidy can, for example, be Down syndrome, trisomy-13, trisomy-18, Turner syndrome, or Klinefelter syndrome.
Any biological fluid can be used in performing the method of the invention, including, without limitation, amniotic fluid, serum, plasma, urine, cerebrospinal fluid, breast milk, mucus, and saliva, preferably, amniotic fluid or maternal serum.
In a further embodiment, the proteomic profile of the test sample comprises information of at least 2 proteins, or at least 5 proteins, or at least 10 proteins, or at least 20 proteins, or at least 50 proteins.
In a specific embodiment, the proteomic profile is a mass spectrum.
In another embodiment, the mass spectrum comprises at least one unique expression signature in the 3 to 5 kDa range of the mass spectrum.
In yet another embodiment, the mass spectrum comprises at least one unique expression signature in the 10 to 12 kDa range of the mass spectrum.
In a further embodiment, the maternal condition is intra-amniotic infection, and the unique expression signature is an extra peak in the 10 to 11 kDa molecular weight range in the test sample, which is indicative of intra-amniotic infection.
In a different embodiment, the proteomic profile is produced by Western blot analysis.
In another embodiment, the biological fluid is that of a human, and the proteomic profile includes information of the expression of one or more of the proteins selected from the group consisting of: macrophage capping protein, neutrophil gelatinase-associated lipocalin, myeloperoxidase; L-plastin; azurocidin; antibacterial protein FALL-39; Gp340 variant protein; Ebner salivary gland protein homologoue (GenBank Accession No. 355392); leukocyte elastase inhibitor; calgranulin A; calgranulin B; cofilin; moesin; profilin I, cronin-like protein p57; annexin II, fibronectin; glia-derived nexin; antithrombin-III; squamous cell carcinoma antigen 1, squamous cell carcinoma antigen 2; serpin 12; cystatin A; cystatin B; cystatin C; IGFBP-1; Vitamin D-binding protein; apolipoprotein A-I; 14-3-3 protein sigma; 14-3-3 protein zeta/delta; gelsolin; lactotransferrin; phosphoglycerate kinase 1; phosphoglycerate mutase 1; and transketolase; or a fragment, precursor, or naturally occurring variant thereof.
In a further embodiment, the proteomic profile includes information of the expression of one or more of the proteins selected from the group consisting of macrophage capping protein; neutrophil gelatinase-associated lipocalin; myeloperoxidase; L-plastin; azurocidin; antibacterial protein FALL-39; leukocyte elastase inhibitor; calgranulin A; calgranulin B; profilin I, glia-derived nexin; serpin 12; cystatin A; and IGFBP-1; or a fragment, precursor, or naturally occurring variant thereof.
The foregoing method is suitable for the diagnosis of various fetal and maternal conditions, including, without limitation, intra-amniotic infection, developmental defects, including defects of an organ system, musculoskeletal deformities, and conditions resulting from chromosomal aneuploidies, such as Down syndrome, trisomy-13, trisomy-18, Turner syndrome, or Klinefelter syndrome.
If the proteomic profile of the test sample is essentially the same as the proteomic profile of the normal sample, the subject is determined to be free of the maternal or fetal condition.
If the proteomic profile contains essentially the same unique expression signature as a diseased sample, the patient is diagnosed with the corresponding maternal or fetal condition.
In another aspect, the invention concerns a method for the diagnosis of intra-amniotic infection, comprising
(a) comparing the proteomic profile of a test sample of a biological fluid obtained from a pregnant female mammal with the proteomic profile of a normal sample, or a reference proteomic profile, wherein the proteomic profiles provide information of the mass of the proteins present in the samples, or the proteolytic fragments thereof; and
(b) diagnosing the mammal with intra-amniotic infection if the proteomic profile of the test sample shows a unique expression signature in the 3-5 and/or 10-12 KDa molecular weight range.
In a further aspect, the invention concerns a method for the diagnosis of intra-amniotic infection, comprising:
(a) comparing the proteomic profile of a test sample of a biological fluid obtained from a pregnant female mammal with the proteomic profile of a normal sample; and
(b) diagnosing the mammal with intra-amniotic infection if at least one protein selected from the group consisting of IGFB-1, profilin, ceruloplasmin, L-plastin, and calgraulin, or a fragment, precursor or naturally occurring variant thereof, is differentially expressed in the test sample relative to the normal sample.
In a particular embodiment, at least one of IGFBP-1, profilin, ceruloplasmin, and calgranulin, or a fragment, precursor, or naturally-occurring variant thereof, is overexpressed in the test sample relative to the normal sample.
In another embodiment, L-plastin is underexpressed in the test sample relative to the normal sample.
In yet another embodiment, the presence of IGFBP-1 is detected by identifying the proteolytic fragment shown in
In another aspect, the invention concerns a method for the diagnosis of a chromosomal aneuploidy, comprising:
(a) comparing the proteomic profile of a test sample of a biological fluid obtained from a pregnant female mammal with the proteomic profile of a normal sample, or a reference proteomic profile, wherein the proteomic profiles provide information of the mass of the proteins present in the samples, or the proteolytic fragments thereof; and
(b) diagnosing the mammal with the chromosomal aneuploidy if the proteomic profile of the test sample shows a unique expression signature in the 4 to 15 KDa molecular weight range.
In a different aspect, the invention concerns a method for the diagnosis of a developmental defect of a fetus, comprising:
(a) comparing the proteomic profile of a test sample of a biological fluid obtained from a pregnant female mammal with the proteomic profile of a normal sample, or a reference proteomic profile; and
(b) confirming the presence of the developmental defect if at least one actin-modulating protein, or a fragment, precursor, or naturally occurring variant thereof, is differentially expressed in the test sample relative to the normal sample.
In a particular embodiment of this method, the actin-modulating protein is selected from the group consisting of moesin, p57, gelsolin, and a 14-3-3 protein.
In a further aspect, the invention concerns a method for the diagnosis of a maternal or fetal infection or immune-response related disorder, comprising
(a) comparing the proteomic profile of a test sample of a biological fluid obtained from a pregnant female mammal with the proteomic profile of a normal sample, or a reference proteomic profile; and
(b) confirming the presence of the maternal or fetal infection or immune-response related disorder, if at least one protein selected from the group consisting of macrophage capping protein (MCP), leukocyte elastase, neutrophil gelatinase-associated lipcalcin (NGAL), myeloperoxidase, L-plastin, calgranulin, FALL-39, azyrocidin (CAP37), proteases and protease inhibitors, is differentially expressed in the test sample relative to the normal sample.
In a still further aspect, the invention concerns a method for the diagnosis of neonatal sepsis, comprising detecting in the proteomic profile of a biological fluid obtained from a pregnant females mammal the presence of Gp-340.
In yet another aspect, the invention concerns a proteomic profile of a biological fluid comprising information of one or more proteins selected from the group consisting of macrophage capping protein, neutrophil gelatinase-associated lipocalin, myeloperoxidase; L-plastin; azurocidin; antibacterial protein FALL-39; Gp340 variant protein; Ebner salivary gland protein homologoue (GenBank Accession No. 355392); leukocyte elastase inhibitor; calgranulin A; calgranulin B; cofilin; moesin; profilin I, cronin-like protein p57; annexin II, fibronectin; glia-derived nexin; antithrombin-III; squamous cell carcinoma antigen 1, squamous cell carcinoma antigen 2; serpin 12; cystatin A; cystatin B; cystatin C; IGFBP-1; Vitamin D-binding protein; apolipoprotein A-I; 14-3-3 protein sigma; protein zeta/delta; gelsolin; lactotransferrin; phosphoglycerate kinase 1; phosphoglycerate mutase 1; and transketolase; or a fragment, precursor, or naturally occurring variant thereof.
In a further aspect, the invention concerns a proteomic profile of a biological fluid comprising information of one or more proteins selected from the group consisting of macrophage capping protein; neutrophil gelatinase-associated lipocalin; myeloperoxidase; L-plastin; azurocidin; antibacterial protein FALL-39; leukocyte elastase inhibitor; calgranulin A; calgranulin B; profilin I, glia-derived nexin; serpin 12; cystatin A; and IGFBP-1; or a fragment, precursor, or naturally occurring variant thereof.
The invention further concerns a proteomic profile of a biological fluid characteristic of intra-amniotic infection, comprising information confirming the presence of a protein selected from the group consisting of IGFB-1, profilin, ceruloplasmin, L-plastin, and calgraulin.
In another aspect, the invention concerns a proteomic profile of a biological fluid characteristic of intra-amniotic infection represented in a form providing information of the molecular weight of proteins present in the biological fluid, or the proteolytic fragments thereof, comprising a unique expression signature in the 3-5 KDa and/or 10-12 KDa molecular weight range.
In a further aspect, the invention concerns the proteomic profile essentially as shown in any one of
In a particular embodiment, the proteomic profile is analyzed in a microarray format.
Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Singleton et al., Dictionary of Microbiology and Molecular Biology 2nd ed., J. Wiley & Sons (New York, N.Y. 1994) provides one skilled in the art with a general guide to many of the terms used in the present application.
The term “proteome” is used herein to describe a significant portion of proteins in a biological sample at a given time. The concept of proteome is fundamentally different from the genome. While the genome is virtually static, the proteome continually changes in response to internal and external events.
The term “proteomic profile” is used to refer to a representation of the expression pattern of a plurality of proteins in a biological sample, e.g. a biological fluid at a given time. The proteomic profile can, for example, be represented as a mass spectrum, but other representations based on any physicochemical or biochemical properties of the proteins are also included. Thus the proteomic profile may, for example, be based on differences in the electrophoretic properties of proteins, as determined by two-dimensional gel electrophoresis, e.g. by 2-D PAGE, and can be represented, e.g. as a plurality of spots in a two-dimensional electrophoresis gel. Differential expression profiles may have important diagnostic value, even in the absence of specifically identified proteins. Single protein spots can then be detected, for example, by immunoblotting, multiple spots or proteins using protein microarrays. The proteomic profile typically represents or contains information that could range from a few peaks to a complex profile representing 50 or more peaks. Thus, for example, the proteomic profile may contain or represent at least 2, or at least 5 or at least 10 or at least 15, or at least 20, or at least 25, or at least 30, or at least 35, or at least 40, or at least 45, or at least 50 proteins.
The term “pathologic condition” is used in the broadest sense and covers all changes and phenomena that compromise the well-being of a subject. Pathologic maternal conditions include, without limitation, intra-amniotic infection, conditions of fetal or maternal origin, such as, for example preeclampsia, and preterm labor and delivery. Pathologic fetal conditions include, without limitation, chromosomal defects (aneuploidies), such as Down syndrome, and all abnormalities in gestational age and fetal maturity.
The term “state of a pathologic [maternal or fetal] condition” is used herein in the broadest sense and refers to the absence, presence, extent, stage, nature, progression or regression of the pathologic condition.
The term “unique expression signature” is used to describe a unique feature or motif within the proteomic profile of a biological sample (e.g. a reference sample) that differs from the proteomic profile of a corresponding normal biological sample (obtained from the same type of source, e.g. biological fluid) in a statistically significant manner.
The terms “intra-amniotic infection (IAI),” “amniotic fluid infection,” “amnionitis,” and “clinical chorioamnionitis” are used interchangeably, and refer to an acute infection, including, but not restricted to bacterial, of the amniotic fluid and intrauterine contents during pregnancy.
“Patient response” can be assessed using any endpoint indicating a benefit to the patient, including, without limitation, (1) inhibition, at least to some extent, of the progression of a pathologic condition, (2) prevention of the pathologic condition, (3) relief, at least to some extent, of one or more symptoms associated with the pathologic condition; (4) increase in the length of survival following treatment; and/or (5) decreased mortality at a given point of time following treatment.
The term “treatment” refers to both therapeutic treatment and prophylactic or preventative measures, wherein the object is to prevent or slow down (lessen) the targeted pathologic condition or disorder. Those in need of treatment include those already with the disorder as well as those prone to have the disorder or those in whom the disorder is to be prevented.
“Congenital malformation” is an abnormality which is non-hereditary but which exists at birth.
B. Detailed DescriptionThe present invention concerns methods and means for an early, reliable and non-invasive testing of maternal and fetal conditions based upon the proteomic profile of a biological fluid of the mother or fetus. The invention utilizes proteomics techniques well known in the art, as described, for example, in the following textbooks, the contents of which are hereby expressly incorporated by reference: Proteome Research: New Frontiers in Functional Genomics (Principles and Practice), M. R. Wilkins et al., eds., Springer Verlag, 1007; 2-D Proteome Analysis Protocols, Andrew L Link, editor, Humana Press, 1999; Proteome Research Two-Dimensional Gel Electrophoresis and Identification Methods (Principles and Practice), T. Rabilloud editor, Springer Verlag, 2000; Proteome Research: Mass Spectrometry (Principles and Practice), P. James editor, Springer Verlag, 2001; Introduction to Proteomics, D. C. Liebler editor, Humana Press, 2002; Proteomics in Practice: A Laboratory Manual of Proteome Analysis, R. Westermeier et al., eds., John Wiley & Sons, 2002.
One skilled in the art will recognize many methods and materials similar or equivalent to those described herein, which could be used in the practice of the present invention. Indeed, the present invention is in no way limited to the methods and materials described.
1. Identification of Proteins and Polypeptides Expressed in Biological Fluids
According to the present invention, proteomics analysis of biological fluids can be performed using a variety of methods known in the art.
Typically, protein patterns (proteome maps) of samples from different sources, such as normal biological fluid (normal sample) and a test biological fluid (test sample), are compared to detect proteins that are up- or down-regulated in a disease. These proteins can then be excised for identification and full characterization, e.g. using peptide-mass fingerprinting and/or mass spectrometry and sequencing methods, or the normal and/or disease-specific proteome map can be used directly for the diagnosis of the disease of interest, or to confirm the presence or absence of the disease.
In comparative analysis, it is important to treat the normal and test samples exactly the same way, in order to correctly represent the relative abundance of proteins, and obtain accurate results. The required amount of total proteins will depend on the analytical technique used, and can be readily determined by one skilled in the art. The proteins present in the biological samples are typically separated by two-dimensional gel electrophoresis (2-DE) according to their pI and molecular weight. The proteins are first separated by their charge using isoelectric focusing (one-dimensional gel electrophoresis). This step can, for example, be carried out using immobilized pH-gradient (IPG) strips, which are commercially available. The second dimension is a normal SDS-PAGE analysis, where the focused IPG strip is used as the sample. After 2-DE separation, proteins can be visualized with conventional dyes, like Coomassie Blue or silver staining, and imaged using known techniques and equipment, such as, e.g. Bio-Rad GS800 densitometer and PDQUEST software, both of which are commercially available. Individual spots are then cut from the gel, destained, and subjected to tryptic digestion. The peptide mixtures can be analyzed by mass spectrometry (MS). Alternatively, the peptides can be separated, for example by capillary high pressure liquid chromatography (HPLC) and can be analyzed by MS either individually, or in pools.
Mass spectrometers consist of an ion source, mass analyzer, ion detector, and data acquisition unit. First, the peptides are ionized in the ion source. Then the ionized peptides are separated according to their mass-to-charge ratio in the mass analyzer and the separate ions are detected. Mass spectrometry has been widely used in protein analysis, especially since the invention of matrix-assisted laser-desorption ionisation/time-of-flight (MALDI-TOF) and electrospray ionisation (ESI) methods. There are several versions of mass analyzer, including, for example, MALDI-TOF and triple or quadrupole-TOF, or ion trap mass analyzer coupled to ESI. Thus, for example, a Q-Tof-2 mass spectrometer utilizes an orthogonal time-of-flight analyzer that allows the simultaneous detection of ions across the full mass spectrum range. For further details see, e.g. Chemusevich et al., J. Mass Spectrom. 36:849-865 (2001).
If desired, the amino acid sequences of the peptide fragments and eventually the proteins from which they derived can be determined by techniques known in the art, such as certain variations of mass spectrometry, or Edman degradation.
2. Fetal-Maternal Conditions Benefiting from Early and Non-Invasive Diagnosis
a. Intra-Amniotic Infection
Intra-amniotic infection (IAI) is an acute bacterial infection of the amniotic fluid and intrauterine contents during pregnancy. Prospective studies indicate that IAI occurs in 4% to 10% of all deliveries (Newton, E. R., Prihoda, T. J., and Gibbs, R. S.: Logistic regression analysis of risk factors for intra-amniotic infection. Obstet. Gynecol. 73:571, 1989; Soper, D. E., Mayhall, C. G., and Dalton, H. P.: Risk factors for intraamniotic infection: a prospective epidemicologic study. American Journal of Obstetrics and Gynecology 161:562, 1989; and Lopez-Zeno, J. A., Peaceman, A. M., Adashek, J. A., and Socol, M. L.: A controlled trial of a program for the active management of labor. N. Engl. J. Med. 326:450, 1992). Other terms used to describe IAI include amniotic fluid infection, amnionitis, and clinical chorioamnionitis. Intra-amniotic infection is clinically diagnosed by maternal fever, uterine tenderness, leukocytosis, and fetal tachycardia and should be distinguished from histologic chorioamnionitis. Intra-amniotic infection is an important cause of maternal and neonatal morbidity. Intra-amniotic infection accounts for 10-40% of cases of febrile morbidity in the peripartum period and is associated with 20-40% of cases of early neonatal sepsis and pneumonia (Newton, E. R.: Chorioamnionitis and intraamniotic infection. Clin. Obstet. Gynecol. 36:795, 1993). Maternal bacteremia occurs in 2-6% of patients with IAI and postpartum infectious morbidity is increased. There is also an increased risk of dysfunctional labor and cesarean delivery among patients with IAI. Duff et al. reported a 75% incidence of dysfunctional labor and a 34% incidence of cesarean delivery among patients who developed intra-amniotic infection while in labor (Duff, P., Sanders, R., and Gibbs, R. S.: The course of labor in term pregnancies with chorioamnionitis. American Journal of Obstetrics and Gynecology 147:391, 1983). Intra-amniotic infection is also associated with increased neonatal morbidity and mortality, particularly among preterm neonates. In general, there is a three to four-fold increase in perinatal mortality among low birth weight neonates born to mothers with IAI (Gibbs, R. S., Castillo, M. A., and Rodgers, P. J.: Management of acute chorioamnionitis. American Journal of Obstetrics and Gynecology 136:709, 1980; Gilstrap, L. C., III, Leveno, K. J., Cox, S. M., Burris, J. S., Mashburn, M., and Rosenfeld, C. R.: Intrapartum treatment of acute chorioamnionitis: impact on neonatal sepsis. Am. J. Obstet. Gynecol. 159:579, 1988). There are also increases in respiratory distress syndrome, intraventricular hemorrhage, and neonatal sepsis Morales, W. J.: The effect of chorioamnionitis on the developmental outcome of preterm infants at one year. Obstetrics and Gynecology 70:183, 1987). Recently, IAI has been implicated in neonatal periventricular leukomalacia and cerebral palsy; the risks of cerebral white matter damage and cerebral palsy are nine-fold greater in the setting of intra-amniotic infection Bejar, R., Wozniak, P., Allard, M., Benirschke, K., Vaucher, Y., Coen, R., Berry, C., Schragg, P., Villegas, I., and Resnik, R.: Antenatal origin of neurologic damage in newborn infants. I. Preterm infants. Am. J. Obstet. Gynecol. 159:357, 1988; Grether, J. K. and Nelson, K. B.: Maternal infection and cerebral palsy in infants of normal birth weight. JAMA 278:207, 1997). Finally, subclinical IAI has been found in at least 10% of women in preterm labor with intact fetal membranes, suggesting that IAI is an important, and potentially preventable, cause of prematurity (Romero, R., Avila, C., Brekus, C. A., and Morotti, R.: The role of systemic and intrauterine infection in preterm parturition. Annuals of the New York Academy of Sciences 622:355, 1991). A literature review by Newton demonstrated incidences of clinical IAI of 41% at gestational ages less than 27 weeks, 15% at gestational ages of 27-37 weeks, and 2% at gestations of 38 weeks or greater (Newton et al., supra). Bacteria indigenous to the lower genital tract have also been recovered from the amniotic fluid of 10-20% of all women in preterm labor with intact fetal membranes without clinical signs of intraamniotic infection (Romero et al., supra), and in up to 67% of women in preterm labor with pregnancies ending at 23-24 weeks (Watts, D. H., Krohn, M. A., Hillier, S. L., and Eschenbach, D. A.: The association of occult amniotic fluid infection with gestational age and neonatal outcome among women in preterm labor. Obstet Gynecol 79:351, 1992). Most of these patients deliver rapidly, and clinically apparent IAI develops in many. These observations support the hypothesis that ascending, initially subclinical intrauterine infections-precede preterm labor and may be an important cause of extreme preterm deliveries.
b. Preeclampsia
Preeclampsia, defined as maternal hypertension accompanied by proteinuria, edema, or both, occurs in 7% of pregnancies not terminating in the first trimester. Although the cause is unknown, it is more common in extremes of age in childbearing, maternal diabetes, pregnancies with multiple gestations, and pre-existing maternal renal disease and or hypertension. Preeclampsia is associated with increases in perinatal mortality, and may also lead to eclampsia, characterized by maternal seizures and increased maternal mortality. Currently the mainstay of therapy for preeclampsia is delivery and anticonvulsant prophylaxis with magnesium sulfate. Prior to the advent of magnesium sulfate therapy, the observed maternal mortality was 20-30%. However, with prompt diagnosis, allowing anticonvulsant therapy with magnesium sulfate, anti-hypertensives, and delivery the maternal mortality has been reduced to near zero.
Unfortunately, the diagnosis of preeclampsia based upon commonly recognized symptoms and signs is frequently difficult, and occurs late in the course of the disease. Frequently fetal compromise in growth or well-being is the first recognized manifestation of preeclampsia. Laboratory markers for preeclampsia include quantitation of proteinuria, and elevated serum concentrations of uric acid or creatinine. There are no currently available serum markers for early preeclampsia or markers which identify women which will develop preeclampsia. Recently prospective serum markers including leptin and uric acid have been associated with subsequent preeclampsia in one study (Gursoy T, et al. Preeclampsia disrupts the normal physiology of leptin: Am J Perinatol. 19(6):303-10, 2002) but much work is needed to confirm these findings. Development of early and reliable markers for preeclampsia is imperative to allow for therapy and intervention to optimize the outcome for the neonate and mother.
c. Preterm Labor and Delivery
Preterm delivery is defined as birth prior to the 37th completed week of gestation. The incidence of preterm birth in the United States is 10-11% of all live births, and is increasing despite aggressive treatment of preterm labor. Overall, prematurity and its consequences are responsible for 80% of perinatal deaths not attributable to congenital malformations and add approximately $5 billion annually to the national health care budget. Risk factors for preterm birth include non-white race, young age, low socioeconomic status, maternal weight below 55 kg, nulliparity, 1st trimester bleeding, multiple gestations (Meis P J, Michielutte R, Peters T J, et al. Factors associated with preterm birth in Cardiff, Wales: II. Indicated and spontaneous preterm birth. Am J Obstet Gynecol 173:597-602, 1995)
Unfortunately the prediction of patients at risk for spontaneous preterm birth has been generally disappointing (Creasy R K, lams JD. Preterm labor and delivery. In Maternal-Fetal Medicine, Creasy R K, Resnik R (eds.). W.B. Saunders Company, Philadelphia, Pa. 4th edition, 1999. Pages 498-531). Previous attempts at defining the population at greatest risk for preterm birth, and thereby potentially benefiting from early intervention have included risk-scoring indices, biochemical detection of cervical fetal fibronectin, ultrasound measurement of cervical length, and home uterine activity monitoring. These programs have been both costly, and have been hampered by the inability to predict with accuracy which patients might benefit from early intervention or prophylaxis. All suffer from poor positive predictive value of approximately 30%, with the majority of patients identified as “at risk” delivering at term. Interventions, including pharmacologic treatment to inhibit uterine contractions, are efficacious, but depend upon the early and reliable diagnosis of preterm labor. Early and reliable markers to identify patients at greatest risk for preterm birth are therefore necessary to reduce the tremendous costs and neonatal mortality and morbidity associated with preterm birth.
d. Chromosomal Aneuploidies
Chromosomal abnormalities are a frequent cause of perinatal morbidity and mortality. Chromosomal abnormalities occur with an incidence of 1 in 200 live births. The major cause of these abnormalities is chromosomal aneuploidy, an abnormal number of chromosomes inherited from the parents. One of the most frequent chromosomal aneuploidies is trisomy-21 (Down syndrome), which has an occurrence of 1 in 800 livebirths (Hook E B, Hamerton J L: The frequency of chromosome abnormalities detected in consecutive newborn studies: Differences between studies: Results by sex and by severity of phenotypic involvement. In Hook E B, Porter I H (eds): Population Cytogenetics, pp 63-79. New York, Academic Press, 1978). The primary risk factor for trisomy-21 is maternal age greater than 35, but 80% of children with trisomy-21 are born to women younger than 35 years of age. Other common aneuploidic conditions include trisomies 13 and 18, Turner Syndrome and Klinefelter syndrome.
Because 80% of children with trisomy-21 are born to women younger than 35 years of age, prenatal diagnostic screening programs designed on the basis of maternal age alone are inefficient. Prenatal screening programs have therefore been supplemented with maternal serum screening for analytes associated with fetal chromosomal aneuploidy, ultrasound, or a combination of both. Candidate serum markers that have been widely utilized include alpha-fetoprotein (AFP), unconjugated estriol, human choriogonadotrophic hormone (hHCG), and inhibin-A. However, with a screen positive rate of 2-5%, the detection rate for trisomy-21 and other aneuploidies has been disappointing, with detection rates of only 70-86% (Cuckle H. Biochemical screening for Down syndrome. Eur J Obstet Gynecol Reprod Biol. 92(1):97-101, 2000). Further, the rate of true positive tests, i.e., trisomy-21 among those with a screen positive test is only 1-2%, resulting in an overall false positive rate in excess of 98%.
The definitive diagnosis of chromosomal aneuploidies following maternal serum screening and ultrasound requires a mid-trimester genetic amniocentesis. This is an invasive procedure associated with a 0.5% risk of loss of the pregnancy. Further, chromosomal analysis of amniotic fluid cells is a labor-intensive and time consuming procedure, taking up to 2 weeks. Reliable tests are therefore necessary to improve the detection of chromosomal aneuploidies from maternal serum, reduce the unacceptably high false positive rate of maternal screening, and increase the speed and efficiency of diagnosis from amniotic fluid following amniocentesis.
3. Diagnosis of Maternal/Fetal Conditions Using the Proteomic Profile of Biological Fluids
The present invention provides an early and reliable, non-invasive method for the diagnosis of the foregoing and other similar maternal/fetal conditions by proteomic analysis of biological fluids, such as, for example, amniotic fluid, serum, plasma, urine, cerebrospinal fluid, breast milk, mucus, or saliva.
As noted before, in the context of the present invention the term “proteomic profile” is used to refer to a representation of the expression pattern of a plurality of proteins in a biological sample, e.g. a biological fluid at a given time. The proteomic profile can, for example, be represented as a mass spectrum, but other representations based on any physicochemical or biochemical properties of the proteins are also included. Although it is possible to identify and sequence all or some of the proteins present in the proteome of a biological fluid, this is not necessary for the diagnostic use of the proteomic profiles generated in accordance with the present invention. Diagnosis of a particular disease can be based on characteristic differences (unique expression signatures) between a normal proteomic profile, and proteomic profile of the same biological fluid obtained under the same circumstances, when the disease or pathologic condition to be diagnosed is present. The unique expression signature can be any unique feature or motif within the proteomic profile of a test or reference biological sample that differs from the proteomic profile of a corresponding normal biological sample obtained from the same type of source, in a statistically significant manner. For example, if the proteomic profile is presented in the form of a mass spectrum, the unique expression signature is typically a peak or a combination of peaks that differ, qualitatively or quantitatively, from the mass spectrum of a corresponding normal sample. Thus, the appearance of a new peak or a combination of new peaks in the mass spectrum, or any statistically significant change in the amplitude or shape of an existing peak or combination of existing peaks in the mass spectrum can be considered a unique expression signature. When the proteomic profile of the test sample obtained from a mammalian subject is compared with the proteomic profile of a reference sample comprising a unique expression signature characteristic of a pathologic maternal or fetal condition, the mammalian subject is diagnosed with such pathologic condition if it shares the unique expression signature with the reference sample.
A particular pathologic maternal/fetal condition can be diagnosed by comparing the proteomic profile of a biological fluid obtained from the subject to be diagnosed with the proteomic profile of a normal biological fluid of the same kind, obtained and treated the same manner. If the proteomic profile of the test sample is essentially the same as the proteomic profile of the normal sample, the subject is considered to be free of the subject pathologic maternal/fetal condition. If the proteomic profile of the test sample shows a unique expression signature relative to the proteomic profile of the normal sample, the subject is diagnosed with the maternal/fetal condition in question.
Alternatively or in addition, the proteomic profile of the test sample may be compared with the proteomic profile of a reference sample, obtained from a biological fluid of a subject independently diagnosed with the pathologic maternal/fetal condition ion question. In this case, the subject is diagnosed with the pathologic condition if the proteomic profile of the test sample shares at least one feature, or a combination of features representing a unique expression signature, with the proteomic profile of the reference sample.
In the methods of the present invention the proteomic profile of a normal biological sample plays an important diagnostic role. As discussed above, if the proteomic profile of the test sample is essentially the same as the proteomic profile of the normal biological sample, the patient is diagnosed as being free of the pathologic maternal/fetal condition to be identified. This “negative” diagnosis is of great significance, since it eliminates the need of subjecting a patient to unnecessary treatment or intervention, which could have potential side-effects, or may otherwise put the patient, fetus, or neonate at risk. The data are analyzed to determine if the differences are statistically significant.
The sensitivity of the diagnostic methods of the present invention can be enhanced by removing the proteins found both in normal and diseased proteome at essentially the same expression levels (common proteins, such as albumin and immunoglobulins) prior to analysis using conventional protein separation methods. The removal of such common proteins, which are not part of the unique expression signature, results in improved sensitivity and diagnostic accuracy. Alternatively or in addition, the expression signatures of the common proteins can be eliminated (or signals can be removed) during computerized analysis of the results, typically using spectral select algorithms, that are machine oriented, to make diagnostic calls.
The results detailed in the Examples below present proteomic profiles characteristics of intraamniotic infection (IAI) that differ from the normal proteomic profile of amniotic fluid in a statistically significant manner. In addition, the Examples present expression markers and unique expression signatures characteristic of IAI and Down syndrome, respectively.
Statistical methods for comparing proteomic profiles are well known in the art. For example, in the case of a mass spectrum, the proteomic profile is defined by the peak amplitude values at key mass/charge (M/Z) positions along the horizontal axis of the spectrum. Accordingly, a characteristic proteomic profile can, for example, be characterized by the pattern formed by the combination of spectral amplitudes at given M/Z vales. The presence or absence of a characteristic expression signature, or the substantial identity of two profiles can be determined by matching the proteomic profile (pattern) of a test sample with the proteomic profile (pattern) of a reference or normal sample, with an appropriate algorithm. A statistical method for analyzing proteomic patterns is disclosed, for example, in Petricoin III, et al., The Lancet 359:572-77 (2002).; Issaq et al., Biochem Biophys Commun 292:587-92 (2002); Ball et al., Bioinformatics 18:395-404 (2002); and Li et al., Clinical Chemistry Journal, 48:1296-1304 (2002).
4. Screening Assays
The proteomic profiles of the invention find further utility in screening assays to identify drug candidates for the treatment of a particular maternal/fetal condition. Such screening assays are based on the ability of a test molecule to convert a proteomic profile containing an expression signature characteristic of the maternal/fetal condition to be treated into a proteomic profile devoid of the expression signature. In one particular embodiment, the ability of the test compound to convert a pathologic expression profile into a normal expression profile is tested. In another embodiment, the screening assay tests the ability of a test compound to convert a unique expression signature characteristic of a pathologic condition into a corresponding normal expression signature.
Such screening assays can be performed in vitro by treatment of a diseased biological sample and comparing the proteomics expression profiles before and after treatment. Alternatively or in addition, drug screening can be performed by treating a laboratory animal exhibiting the target pathologic maternal/fetal condition with a test compound, taking samples of a biological fluid of the animal before and after treatment, and comparing the proteomic profiles of the two samples. In this assay, it is also possible to take samples of biological fluid at various time points following treatment, and follow the time course of treatment. These methodologies may be applied also to characterize the toxicology of pharmaceutical agents, as well as to identify optimal candidates for specific therapies.
The test compounds can, for example, be peptides, non-peptide small organic molecules, proteins, polypeptides, antibodies (including antibody fragments), antisense molecules, oligonucleotide decoys, and any other classes of molecules that have been used previously as drugs or drug candidates.
The biological fluid can, for example, be amniotic fluid, serum (e.g. maternal serum), plasma, urine, cerebrospinal fluid, breast milk, mucus, or saliva.
Therapeutically active compounds identified can be formulated in conventional pharmaceutical formulations. A compendium of art-known formulations is found in Remington's Pharmaceutical Sciences, latest edition, Mack Publishing Company, Easton, Pa. Reference to this manual is routine in the art.
5. Protein Arrays
Both the diagnostic and the screening assays discussed above can be performed using protein arrays. In recent years, protein arrays have gained wide recognition as a powerful means to detect proteins, monitor their expression levels, and investigate protein interactions and functions. They enable high-throughput protein analysis, when large numbers of determinations can be performed simultaneously, using automated means. In the microarray or chip format, that was originally developed for DNA arrays, such determinations can be carried out with minimum use of materials while generating large amounts of data.
Although proteome analysis by 2D gel electrophoresis and mass spectrometry, as described above, is very effective, it does not always provide the needed high sensitivity and this might miss many proteins that are expressed at low abundance. Protein microarrays, in addition to their high efficiency, provide improved sensitivity.
Protein arrays are formed by immobilizing proteins on a solid surface, such as glass, silicon, micro-wells, nitrocellulose, PVDF membranes, and microbeads, using a variety of covalent and non-covalent attachment chemistries well known in the art. The solid support should be chemically stable before and after the coupling procedure, allow good spot morphology, display minimal nonspecific binding, should not contribute a background in detection systems, and should be compatible with different detection systems.
In general, protein microarrays use the same detection methods commonly used for the reading of DNA arrays. Similarly, the same instrumentation as used for reading DNA microarrays is applicable to protein arrays.
Thus, capture arrays (e.g. antibody arrays) can be probed with fluorescently labelled proteins from two different sources, such as normal and diseased biological fluids. In this case, the readout is based on the change in the fluorescent signal as a reflection of changes in the expression level of a target protein. Alternative readouts include, without limitation, fluorescence resonance energy transfer, surface plasmon resonance, rolling circle DNA amplification, mass spectrometry, resonance light scattering, and atomic force microscopy.
For further details, see, for example, Zhou H, et al., Trends Biotechnol. 19:S34-9 (2001); Zhu et al., Current Opin. Chem. Biol. 5:40-45-(2001); Wilson and Nock, Angew Chem Int Ed Engl 42:494-500 (2003); and Schweitzer and Kingsmore, Curr Opin Biotechnol 13:14-9 (2002). Biomolecule arrays are also disclosed in U.S. Pat. No. 6,406,921, issued Jun. 18, 2002, the entire disclosure of which is hereby expressly incorporated by reference.
Further details of the invention will be apparent from the following non-limiting examples.
Example 1 General ProtocolsPrimate Model of Intra-Amniotic Infection
This protocol was approved by the Institutional Animal Care Utilization Committee of the Oregon National Primate Research Center, and guidelines for humane care were followed. Three pregnant rhesus monkeys (Macaca mulatta) with timed gestations were chronically catheterized as previously described (Haluska G J, et al., Temporal changes in uterine activity and prostaglandin response to RU 486 in rhesus macaques in late gestation, Am J Obstet Gynecol 157: 1487-95 (1987); and Gravett M G, et al., An experimental model for intramniotic infection and preterm labor in rhesus monkeys. Am J Obstet Gynecol 171: 1660-7 (1994)). Briefly, at approximately day 110 of gestation (term is 167 days) pregnant animals were conditioned to a jacket and tether system (Ducssay C A, et al., Simplified vest and tether system for maintenance of chronically catheterized pregnant rhesus monkeys. Lab. Anim Sci 38:343-4 (1988)). After conditioning, intrauterine surgery was performed between days 119 and 126 of gestation under general anesthesia. Maternal femoral arterial and venous catheters, fetal arterial and venous catheters, two open-ended intra-amniotic pressure catheters, myometrial electromyographic electrodes, and fetal electrocardiographic electrodes were surgically implanted. All animals received terbutaline sulfate (1 mg intravenously over 3 to 5 hours twice daily) for 1 to 5 days after surgery to control uterine irritability. Animals also received cefazolin (250 mg intravenously every 12 hours), which was discontinued at least 48 hours before inoculation of bacteria.
After postoperative stabilization for 8 to 13 days (day 126 to 138 of gestation), intra-amniotic infection was established by intra-amniotic inoculation of 106 colony-forming units (cfu) of group B Streptococcus, type III, grown in overnight cultures in Todd-Hewitt broth, centrifuged, washed, and suspended in 0.5 ml of saline solution (n=3 animals), 107 cfu of Ureaplasma urealyticum (1 animal) or Mycoplasma hominis (1 animal), grown in broth. Amniotic fluid samples were collected serially from all animals during the study period (daily before inoculation and every 4 to 12 hours after inoculation) for quantitative bacterial cultures, white blood cell analysis by hemocytometer, and cytokine and prostaglandin concentrations (previously reported—Gravett M G, et al., An experimental model for intra-amniotic infection and preterm labor in rhesus monkeys. Am J Obstet Gynecol 171: 1660-7 (1994)).
Fetal electrocardiographic and uterine activity (electromyographic and intra-amniotic pressure) were continuously recorded from surgery until delivery. Uterine contractility was recorded as the area under the contraction curve per hour and expressed as the hourly contraction area (HCA) in millimeters of mercury times seconds/hour.
The maternal cervix was palpated vaginally before infection and serially thereafter. Consistency, effacement, and dilatation were recorded at each examination. After delivery, by cesarean section in all except one animal and vaginally in one animal, decidual, placental, and inter membrane bacterial cultures were obtained form infected animals to confirm infection and histopathologic studies were performed.
Amniotic Fluid Assays
Amniotic fluid samples (3 ml) were immediately centrifuged after collection at 3,000 rpm and 4° C. for 20 minutes. The sediment was saved for cellular analysis and the supernatant stored in pyrogen-free sterile vials at −20° C. until assayed.
Human Study
The study population was drawn from 309 women admitted in premature labor with intact fetal membranes to the University of Washington Medical Center or associated hospitals in Seattle between Jun. 25, 1991 and Jun. 30, 1997, as previously described (Hitti J, et al., Amniotic fluid tumor necrosis factor-α and the risk of respiratory distress syndrome among preterm infants. Am J Obstet Gynecol 177:50-6 (1997)). All women provided written informed consent, and the study protocol was approved by the Institutional Review Boards for all participating hospitals. The participants were at gestational ages of 22 to 34 weeks by last menstrual period or from the earliest available ultrasound. All participants had intact fetal membranes at study enrollment. Preterm labor was defined as regular uterine contractions at a frequency of 10 minutes with either documented cervical change or a cervical dilatation of 1 centimeter or effacement of 50%. Women with cervical dilatation >4 centimeters or ruptured membranes at admission were excluded. Women with multiple gestations, cervical cerclage, placenta previa, abruptio placentae, diabetes, hypertension, and pre-eclampsia were considered eligible if they otherwise met study criteria.
Transabdominal amniocentesis was performed under ultrasound guidance for all study participants and maternal venous blood was also collected by venipuncture at the time of enrollment From this study population, a subset (Tables 1A and B) was retrospectively identified for proteomic analysis as reported here. This subset included 11 patients with evidence of intrauterine infection (as defined by the recovery of a microbial pathogen form amniotic fluid or an amniotic fluid IL-6 concentration of ≧2,000 pg/ml), and a randomly selected subset of 11 patients without intrauterine infection but with preterm birth and 11 patients without infection and with preterm labor responsive to tocolytic therapy and who had subsequent term birth. These patients constitute the study population for this report.
The study population was divided into three groups: 1) those patients with evidence of intrauterine infection, based upon either recovery of microorganisms from amniotic fluid or an amniotic fluid IL-6 concentration of >2,000 pg/ml; 2) those patients with preterm labor and delivery prior to 35 weeks of gestation without evidence of intrauterine infection; and 3) those patients with preterm labor responsive to tocolytic therapy who delivered at ≧35 weeks of gestation. There were no differences in maternal age, race, or parity between these three groups (Tables 1A and B). However, patients with intrauterine infection were seen at a somewhat earlier gestational age at enrollment (p=0.10) and delivered at a significantly earlier gestation age than those patients with preterm delivery without infection or those with term delivery (27.3±0.9 weeks versus 29.8±1.0 and 37.0±0.9 weeks respectively, p<0.0001). In addition, those with intrauterine infection had a significantly shorter enrollment to delivery interval (2.1±5.6 days, compared to 8.4±6.3 and 46.9±5.6 days for the other two groups, p<0.0001). Ninety-one percent of those with intrauterine infection delivered within seven days of enrollment.
Among those eleven patients with infection, microorganisms were recovered from four (2 with Escherichia coli, 1 with Candida albicans, and 1 with mixed anaerobes); all of these patients delivered within seven days. Seven other patients were identified based upon amniotic fluid IL-6 concentrations of greater than 2,000 pg/ml. The mean amniotic fluid concentration of interleukin-6 was 27.7±7.8 ng/ml among these patients, compared to 0.68±0.20 ng/ml among those with preterm delivery without infection and 0.25±0.13 ng/ml among those with preterm labor and term delivery (p<0.01).
Data expressed as mean standard deviation. Analysis by ANOVA for continuous data and Chi-square for categorical data. Abbreviations: PMD, premature delivery <35 weeks; IUI, intrauterine infection; PML, premature labor without delivery.
In the foregoing tables, data are expressed as mean standard deviation. Analysis by ANOVA for continuous data and Chi-square for categorical data. Abbreviations: PMD, premature delivery <35 weeks; IUI, intrauterine infection; PML, premature labor without delivery.
Proteomic Analysis of Amniotic Fluid
1-Dimensional (1-D) Gel Electrophoresis
100 μg of amniotic fluid after reduction with iodoacetamide was loaded on a 15% SDS-PAGE gel. Electrophoresis was conducted at 80V to separate the proteins in the sample. After electrophoresis the gel was stained with Coomasie blue R-250 and images were collected using Bio-Rad GS800 densitometer and PDQUEST software. Individual bands were cut from the gel, destained and digested in-gel with trypsin for 24-48 hrs at 37° C. The peptides were extracted with 0.1% TFA and dried in a speedvac. The extract was dissolved in 0.1% TFA and purified using Zip Tipc18 pipette tips from Millipore. (Marvin L., et al. Identification of proteins from one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis using electrospray quadrupole-time-of-flight tandem mass spectrometry. Rapid Commun Mass Spectrom. 14(14):1287-92, 2000).
2-Dimensional (2-D) Gel Electrophoresis
Amniotic fluid (400-2000 μg) with or without removal of albumin was dissolved in IEF buffer and rehydrated on to a 24 cm IPG strip (pH 3-10) for 12 h at room temperature. After rehydration, the IPG strip was subjected to 1-dimension electrophoresis at 70˜90 kVhrs. The IPG strip was then equilibrated with DTT equilibration buffer I and IAA equilibration buffer II for 15 minutes sequentially, before second dimension SDS-PAGE analysis. The IPG strip was then loaded on to a 4˜20% SDS-PAGE gel and electrophoresis conducted at 120 V for 12 hrs to resolve proteins in the second dimension. The gel was stained with Coomassie Blue R-250 and imaged using Bio-Rad GS800 densitometer and PDQUEST software. Individual spots were cut from the gel, destained and digested in-gel with trypsin for 24-48 hrs at 37 C. The peptides were extracted with 0.1% TFA and purified using Zip Tipc18 pipette tips from Millipore (2-D Proteome analysis protocols: Methods in Molecular Biology: 112, 1999).
HPLC Fractionation
Human amniotic fluid samples after removal of albumin and IgG (1-15 mg protein) were dissolved in 20 mM Tris-HCl, pH 7.5. Anion-exchange chromatography was performed using TSK gel DEAE-5PW column on a Waters 1525 HPLC equipped with an auto sampler and a UV absorbance detector. A linear salt elution gradient was used to fractionate the proteins. Fractions were collected at one minute intervals. Fractions were pooled, digested with trypsin and peptide mixtures were analyzed using the mass spectrometer (Q-Tof-2).
Mass Spectrometry Analysis
(1) Q-Tof-2
Samples after in-gel digestion were analyzed on a Micromass Q-Tof-2 mass spectrometer connected to a Micromass CapLC. The Q-Tof-2 was equipped with a regular Z-spray or nanospray source and connected to a Integrafrit C18 75 um ID×15 cm fused silica capillary column. The instrument was controlled by, and data were acquired on, a Compaq workstation with Windows NT and MassLynx 3.5 software. The Q-Tof-2 was calibrated using Glu1Fibrinopeptide B by direct infusion or injection into the CapLC. A MS/MSMS survey method was used to acquire MS/MSMS spectra. Masses 400 to 1500 were scanned for MS survey and masses 50 to 1900 for MSMS. Primary data analysis was performed on a PC with Windows 2000 and SEQUEST (version 1.3) and/or LUTEFISK. Peak lists were generated, using the built-in automatic functions for peak-picking and applying centroid-fitting to each peak.
(2) LCQ-MS
Protein spots from dried Coomassie blue stained gels were excised and rehydrated/washed for 30 min. in 0.5 ml of 20 mM ammonium bicarbonate, 50% acetonitrile solution. The gel regions were then dried by vacuum centrifugation and digested insitu by rehydrating in 20 nM sequencing grade modified trypsin (ProMega, Madison, Wis., USA) using the method of Courchesne and Patterson, Identification of proteins by matrix-assisted laser desorption/ionization masses, Methods Mol. Biol. 112:487-511 (1999). Tryptic digests were then concentrated by vacuum centrifugation, separated by reverse phase chromatography, and peptides analyzed by a model LCQ ion trap mass spectrometer (ThermoFinnigan, San Jose, Calif.). Samples were separated with Zorbax C-18 0.5 mm×150 mm microbore column using a 10 μL min−1 flow rate and a gradient of 0 to 40% B (75% Acetonitrile in water) over one hour with an 1100 Capillary LC System (Agilent Technologies, Foster City, Calif.). Peptides were introduced directly into the standard ThermoFinnigan electrospray source. MS/MS spectra were acquired in an automated fashion using standard LCQ software and then analyzed further using SEQUEST (ThermoFinnigan). For further details see, Courchesne, P. L. and Patterson, S. D., supra.
Data Analysis
(1) Sequest and DTASelect
Automated analysis of tandem mass spectra (MS/MS) was performed using SEQUEST software (ThermoFinnigan) as described by Yates et al., Methods Mol. Biol. 112:553-69 (1999). SEQUEST matches uninterrupted tandem mass spectra to database peptide sequences. Searches were run with the default parameters using a combined indexed non-redundant database of protein sequences obtained from the Protein Information Resource (release date) and SwissProt (release date). The database was constructed using the Xcalibur Database Manager (ThermoFinnigan). S-Carboxyamidated cysteine was the only considered modification.
Sequest results were further analyzed using DTASelect (The Scripps Research Institute, Tabb, 2002). DTASelect organizes and filters SEQUEST identifications. The default parameters were used except as follows: 1) any database matches including the string “keratin” in the protein description were excluded and 2) spectra from the LCQ mass spectrometer were filtered with a cross correlation score cut-off of 2.4 for the doubly charged ions. Each spectra and proposed sequence pair selected by DTASelect were visually inspected and the final results were input into a spreadsheet (Microsoft Excel) or a database (Microsoft Access) for management.
For further details, see also: Tabb D L, et al., DTASelect and Contrast: Tools for Assembling and Comparing Protein Identifications from Shotgun Proteomics. J. Proteome Res. 1:21-26 (2002).
(2) Lutefisk
Automated de novo sequencing of all spectra was performed using a computer program, Lutefisk 1900 v1.2.5 (Taylor J A, Johnson R S. Implementation and uses of automated de novo peptide sequencing by tandem mass spectrometry. Anal Chem 73(11):2594-604 (2001). Lutefisk generates peptide sequences for spectra of which some are sufficiently detailed for homology-based sequence searches. Modifications, acrylamide, carbamidomethylation, and phosphorylation, were considered.
MALDI Detection Protocol and Parameters
MALDI mass spectrometry was performed on a custom-built time-of-flight reflector mass spectrometer (Jensen O N, et al., Direct observation of UV-crosslinked protein-nucleic acid complexes by matrix-assisted laser desorption ionization mass spectrometry. Rapid Commun Mass Spectrom 7(6):496-501 (1993)) equipped with a two-stage delayed extraction source. Approximately 1 μL of sample solution was mixed with 1 μL SA (Sinapinic acid in 60:40 water/acetonitrile 0.1% TFA final conc.) A 1.0 μL droplet of this analyte/matrix solution was deposited onto a matrix pre-crystallized sample probe and allowed to dry in air. Mass spectra were produced by radiating the sample with a (355 nm) Nd:YAG laser (Spectra Physics) and operating the ion source at 23 kV with a 700 ns/1.0 kV delay. Every mass spectrum was recorded as the sum of 20 consecutive spectra, each produced by a single pulse of photons. Ions from an added standard were used for mass calibration.
SELDI Analysis of Amniotic Fluid
A total of 0.5-3.0 ug protein from amniotic fluid samples was spotted on a Normal Phase NP20 (SiO2 surface), Reverse Phase H4 (hydrophobic surface: C-16 (long chain aliphatic), or immobilized nickel (IMAC) SELDI ProteinChip® array (Ciphergen Biosystems, Inc. Fremont, Calif.). After incubation at room temperature for 1 hour, NP1 and H4 chips were subjected to a 5 ul water wash to remove unbound proteins and interfering substances (ie buffers, salts, detergents). After air-drying for 2-3 minutes, two 0.5 ul applications of a saturated solution of sinapinic acid in 50% acetonitrile (v/v), 0.5% trifluoroacetic acid (v/v) was added and mass analysis was performed by time-of-flight mass spectrometry in a Ciphergen Protein Biology System II (PBS II), Issaq, J. H, et al.: The SELDI-TOF MS Approach to proteomics: Protein Profiling and Biomarker Identification. Biochem Biophys Res Commun. 5; 292(3):587-92, 2000.
Example 2 Identification of Proteins and Polypeptides Expressed in the Amniotic FluidUsing the materials and methods described in Example 1, proteins and polypeptides expressed in normal and infected amniotic fluid were identified. Human and primate amniotic fluid samples (pooled and individual) were subjected to protein separation techniques (1-D, 2-D and HPLC fractionation) as described in Example 1. The separated proteins (gel bands, spots and fractions) were digested with trypsin to generate peptide pools. The peptide pools were analyzed using tandem MS to decipher their amino acid sequence and composition.
Five thousand MS spectra were selected using spectral verification programs. These spectral files were analyzed using de novo sequencing programs (Lutefisk, Peaks) to generate the amino acid sequence corresponding to each peptide. The de novo sequences generated from the peptide pool were used to search protein and DNA databases as described in Example 1.
Using homology maps and sequence verification, expression of a variety of proteins was discovered in the amniotic fluid. The detected proteins were analyzed for potential function based on known structural similarities (sequence homology maps). Proteins belonging to important functional classes involved in a wide range of diseases were discovered. Proteins and polypeptides discovered for the first time in the human amniotic fluid are listed in the following Table 2 under these potential functional categories.
Proteins shown to be differentially expressed by immunoassays also, and proteins more abundantly or uniquely represented in the infected amniotic fluid are separately marked. In this context, relative abundance is defined as the amount of the peptides representing a certain polypeptide or protein in a test sample, relative to a reference sample. Accordingly, a protein is more abundantly represented in infected amniotic fluid if more peptides derived from the same protein are present in infected amniotic fluid than in a non-infected reference sample of amniotic fluid.
Table 3 lists proteins and polypeptides previously known to be present in amniotic fluid, the presence of which was reaffirmed by the present assays. Proteins which are known markers for infection related events are separately marked.
In view of their known biological functions, several proteins listed in the foregoing tables are promising candidates for detecting and monitoring intrauterine conditions. A few examples of such conditions and the corresponding protein markers are discussed below in greater detail.
Actin-Modulating and Related Proteins as Markers of Developmental Defects:
Moesin (Membrane-organizing extension spike protein), listed among the structural proteins in Table 2, is known to be responsible for linking transmembrane proteins to the actin cytoskeleton and implicated in various cell signaling pathways (Speck O, et al.: Moesin functions antagonistically to the Rho pathway to maintain epithelial integrity. Nature 2; 421(6918):83-7, 2003). It was shown that Rho-family GTPases and their effectors to modulate the activities of actin modifying molecules such as Cofilin and Profilin (also listed as a structural protein in Table 2), resulting in cytoskeletal changes associated with growth cone extension or retraction (Tang B L. Inhibitors of neuronal regeneration: mediators and signaling mechanisms. Neurochem Int, 42(3):189-203, 2003). Coronin-like protein p57 (yet another structural protein listed in Table 2) is also involved in actin cross-linking and capping (Weitzdoerfer R et al.: Reduction of actin-related protein complex ⅔ in fetal Down syndrome. Biochem Biophys res Commun. 293:836, 2002) and are dysregulated in known developmental defects. Gelsolin (see, the Gelsolin precursor listed an a transporter/binding protein in Table 2), another actin-modulating protein is also known to be developmentally regulated and important in organ systems (Arai M, Kwiatkowski D J. Differential developmentally regulated expression of gelsolin family members in the mouse. Dev Dyn, 215, 297, 1999). 14-3-3 proteins are also known epithelial markers which participate in signal transduction and differentiation pathways and are essential for normal development of brain and other vital organs (Wu C, Muslin A J. Role of 14-3-3 proteins in early Xenopus development. Mech Dev, 119, 45, 2002).
Accordingly, the listed actin-modulating proteins and other related molecules with important roles during development, that were identified for the first time in human amniotic fluid, could be used to detect developmental defects of various organ systems such as, central nervous system, cardiovascular system and other musculoskeletal deformities, which can, for example, result from chromosomal aneuploides. This is particularly true for Profiling I, which has been shown to be differentially expressed in infected amniotic fluid, and the differential expression of which has been confirmed by immunoassay.
Markers of Infection and Immune-Response Related Disorders:
The present detection of macrophage capping protein, leukocyte elastase, neutrophil gelatinase-associated lipocalicn, myleoperoxidase, L-plastin (lymphocyte cytosolic protein) and calgranulins (see the list of immune response related genes in Table 2) infected amniotic fluid is the first demonstration of the presence and regulation of these proteins in intraamniotic infection. Several of these proteins are known responders of immune cells in response to infection, inflammation and stress. Macrophage capping protein (MCP) is a Ca(2+)-sensitive protein which modulates actin filaments and involved in inflammatory process (Dabiri G A, Molecular cloning of human macrophage capping protein cDNA. A unique member of the gelsolin/villin family expressed primarily in macrophages J Biol Chem 15; 267(23):16545-52, 1992). Similarly, Calgranulins are calcium binding proteins known to play a role in injury and wound healing (Thorey I S. et al. The Ca2+-binding proteins S100A8 and S100A9 are encoded by novel injury-regulated genes. J Biol Chem 21; 276(38):35818-25, 2001). Leukocyte elastase and neutrophil gelatinase-associated lipocalcin (NGAL) are involved in bacteriostatic and baceterolysis mechanisms (Goetz D H. et al. The neutrophil lipocalin NGAL is a bacteriostatic agent that interferes with siderophore-mediated iron acquisition: Mol Cell 10(5):1033-43, 2002).
In addition to the above immunomodulators we also discovered, for the first time, two antibacterial proteins Fall-39 and azurocidin in the infected amniotic fluid. Antibacterial protein Fall-39 (LL-37) binds to bacterial lipopolysaccharides (ips), and is expressed in bone marrow, testis and neutrophils. Fall-39 stimulates the degranulation of mast cells, and is a potent chemotactic factor for mast cells. Besides its antibacterial activities, Fall-39 may have the potential to recruit mast cells to inflammation foci. In the presence of the basal medium E, synthetic FALL-39 was highly active against Escherichia coli D21 and Bacillus megaterium Bm11. A protective role for Fall 39 has been proposed, when the integrity of the skin barrier is damaged, participating in the first line of defense, and preventing local infection and systemic invasion of microbes (Agerberth B, et al.: FALL-39, a putative human peptide antibiotic, is cysteine-free and expressed in bone marrow and testis. Proc Natl Acad Sci USA, 3; 92(1):195-9, 1995).
Azurocidin (CAP37) is a cationic antimicrobial protein isolated from human neutrophils and has important implications in host defense and inflammation. It is released during inflammation and regulates monocyte/macrophage functions, such as chemotaxis, increased survival, and differentiation (Pereira H A. CAP37, a neutrophil-derived multifunctional inflammatory mediator. J Leukoc Biol; 57(6):805-12, 1995).
Proteases and protease inhibitors play a key role in protein regulation and thus control several key physiological mechanisms. We have identified the expression of Serpin family of proteases (Serpin, squamous cell carcinoma antigen 1 & 2, glia derived nexin) for the first time in human amniotic fluid, including intraamniotic infection. The serpin superfamily of serine proteinase inhibitors has a central role in controlling proteinases in many biological pathways and implicated in conformational diseases, such as the amyloidoses, the prion encephalopathies and Huntington and Alzheimer disease (Lomas D A, Carrell R W, Serpinopathies and the conformational dementias. Nat Rev Genet; 3:759, 2002).
Additionally, in intraamniotic infection we identified the expression of Cystatins, well known proteinase inhibitors involved in immunomodulation (Vray B, Hartmann S, Hoebeke J. Immunomodulatory properties of cystatins. Cell Mol Life Sci ;59(9):1503-12, 2002).
The listed proteins are promising markers of infection and/or immune-response related disorders.
It is noteworthy that peptides representing macrophage capping protein, neutrophil gelatinase-associated lipocalin, myeloperoxidase precursor, L-plastin, azurocidin, antibacterial protein Fall-39, calgranulin A, profilin I, glia-derived nexin, serpin 12, and cystatin A were more abundantly or uniquely detected in infected amniotic fluid relative to normal amniotic fluid, and/or showed differential expression in immunoassays. Accordingly, these proteins are particularly important as markers of intra-amniotic infection and/or immune-response related disorders.
Other Disease (Infection) Specific Proteins Detected in Human Amniotic Fluid
Gp-340 variant protein listed in Table 2, which has been detected in human infected amniotic fluid, is a scavenger receptor previously identified in lung. This protein is known to bind to bacteria (streptococcus and variants) The detection of this protein in infected amniotic fluid complements the sensitive proteomic approach of the present invention to identify biomarkers for IAI. Thus, Gp-340 variant protein identified in the infected amniotic fluid lends itself for the detection of neonatal sepsis).
IGFBP-1 (Proteolytic Fragment)
As shown in Table 2, IGFBP-1 has been shown to be differentially expressed in infected amniotic fluid. The insulin-like growth factor (IGF) systems is critically involved in fetal and placental growth and modulates steroid hormone actions in the endometrium through autocrine/paracrine mechanisms. IGF-I and IGF-II stimulated proliferation and differentiation, and maintain differentiated cell functions in several cell types in vitro. Endometrial stromal cells produce IGF-I and IGF-II as well as the high affinity IGF-binding proteins (IGFBPs). The mRNA of six high affinity IGFBPs, which can modulate IGF actions, are expressed in human endometrium. The most abundant IGFBP in human endometrium is IGFBP-1, which is secreted by predecidualized/decidualized endometrial stromal cells in late secretory phase and during pregnancy. This has implications for clinical obstetrics and gynecology, where there is evidence for a pathophysiological role for IGFBP-1 in pre-eclampsia, intrauterine growth restriction, polycystic ovarian syndrome and trophoblast and endometrial neoplasms.
The presence and regulation of an IGFBP-1 proteolytic fragment in human amniotic fluid and maternal serum opens a new way for monitoring intrauterine and maternal conditions associated with pregnancy.
For further details see, also Example 12 below.
Example 3 Protein Expression Profiles of Primate Amniotic Fluid Following Intrauterine InfectionProtein expression profiles of primate amniotic fluid following intrauterine infection, compared with the corresponding normal expression profiles, are shown in
As illustrated in
As shown in
As shown in
It is noteworthy that the diagnostic pattern of human amniotic fluid is in good agreement with the diagnostic pattern of primate amniotic fluid (Examples 3 and 4).
Example 6 Generation of Diagnostic Profiles Using Different Mass SpectrometersThe diagnostic protein expression profile can be detected using different types of mass spectrometers. It has been examined whether different mass spectrometers produce similar diagnostic profiles. If the diagnostic profiles are substantially independent on the type of mass spectrometer, the detected differential protein expression in the amniotic fluid can provide a diagnostic signature for intrauterine infection.
As shown in
In summary, it has been discovered that amniotic fluid proteins and polypeptides exhibit differential expression patterns diagnostic of disease state. The results presented here demonstrate that disease-specific diagnostic patterns can be detected using multiple mass spectrometry approaches. The patterns or protein expression profiles are comparable between humans and primates. The profiles can be used to monitor a time-course (infection or treatment) effect.
Example 7 Quantification of Protein and Polypeptide Expression in Amniotic Fluid for Diagnostic and Prognostic MonitoringSDS-PAGE:
Proteins from human amniotic fluid (AF) containing high salt was precipitated with acetone. 100 μg of amniotic fluid proteins was run on a 15% SDS-PAGE. The gel was stained with Coomassie Blue R-250. The gel image was scanned by Bio-Rad gel Scanner.
100 μg of AF proteins were run on 4-20% SDS-PAGE at 200 V for 60 minutes and transferred to PVDF membrane at 90 mM for 75 minutes. The membrane was blocked with 5% milk PBST for 45 min at RT and incubated with 1 μg/ml primary antibody (Santa Cruz and Dako) overnight at 4 C. After wash with TBST 3 times, the membrane was incubated with secondary antibody IgG-HRP (Sigma) for 90 min at RT and visualized with ECL (Pierce).
The results are shown in
Two micrograms of primary antibody was mixed with 600 μg of AF protein and incubated at 4° C. overnight. 15 μl of protein G Sepharose beads was added and incubated on a shaker for 60 minutes at room temperature. The beads were washed with IP buffer for 6 times.
The results are shown in
It has been examined if the differentially expressed proteins in the amniotic fluid can be used as a lead to measure similar proteins in the maternal serum. This will enable to develop rapid and non-invasive testing for diagnoses and monitoring. The results are shown in
Antibodies: IGFBP-1 (DSL); complement C3, Desmin, neutrophil elastase, NSE antibody (DAKO); calgranulin, ceruloplasmin, TIMP-1, plastin and profiling (Santa Cruz).
Antibody spotting: antibodies were dissolved in 40% glycerol, 60% PBS, pH 7.5 at a concentration of 100 μg/ml and were spotted on aldehyde slides using a Arrayer (Cartesian).
Following a 3 hr incubation in a humid chamber at room temperature, the slides were incubated for one hour in a solution of PBS, pH 7.5 containing 1% BSA (w/v at room temperature with gentle agitation.
Biotinylation of proteins: Biotin-NHS was dissolved in DD water at 50 mg/l. 10 ul of this solution was added into maternal serum protein solution (5 mg/ml in 10 mM PB, pH8.5) and incubated for 3 hours on a shaker. 5 ul of ethanolamine was added to stop the reaction. Biotinylated proteins were diluted in 200 ul of TNB buffer and added to antibody arrays and incubated overnight at 4 C. Following three washes in TNT buffer, streptavidin-HRP was added and incubated for 30 minutes at room temperature. Antigen-Antibody interaction was detected using Cy5-tyramide fluorescence. Slides were scanned on a PE fluorescent scanner for quantification. Images of control and infected slides were overlayed using a image analysis program to generate a pseudocolor representation for relative abundance. The results are shown in
It has been demonstrated that the SELDI-TOF profiles of control and infected amniotic fluid show a unique signature in the mass range of 10-12 KDa (
Western blot analysis of control and infected amniotic fluid using an anti-IGF-BP1 antibody as shown in
Sequencing of the amniotic fluid polypeptides also identified the presence of IGF-BP1 and calgraulins in the infected amniotic fluid (Table 3).
The sequence of the identified novel proteolytic fragment of IGFBP-1 is shown in
Indeed, MS/MS analysis and sequence search results demonstrated that the parent ion 434.89 in the mass spectrum shown in
The utility of proteomic profiling was examined to identify trisomy-21 more accurately using maternal serum screening. This study was performed with a panel of (control (n=6), trisomy-21 (n=6) and trisomy-18 (n=4), well-characterized maternal serum samples (matching amniotic fluid samples for the same cases were tested by standard chromosomal mapping method and positively confirmed the presence of trisomies) and analyzed using SELDI-TOF methodology as described above for the intrauterine infection model.
This further illustrates detection of protein expression patterns in various biological fluids (such as maternal serum) could identify fetal-maternal conditions more accurately and in a non-invasive approach.
In conclusion, the data presented herein demonstrate that differential expression of proteins in the amniotic fluid as well as other biological fluids, such as serum, represents a valid approach for a rapid, non-invasive and accurate diagnosis, prognosis, and monitoring of various maternal/fetal conditions and chromosomal aneuploidies.
Throughout the foregoing description the invention has been discussed with reference to certain embodiments, but it is not so limited. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description and fall within the scope of the appended claims.
All references cited throughout the description, and the references cited therein, are hereby expressly incorporated by reference in their entirety.
Claims
1. A method for predicting pre-term birth in a mammalian subject, comprising:
- (1) comparing the proteomic profile of a test sample of a biological fluid obtained from said mammalian subject with a proteomic profile of a reference sample wherein the test sample proteomic profile and the reference sample proteomic profile comprise information of the expression of at least one of the following: IGFBP-1, Gelsolin precursor, Calgranulin A, Alpha-1-acid glycoprotein 1 precursor, and Alpha-1-antitrypsin precursor; or fragments or naturally occurring variants, and;
- (2) predicting pre-term birth in said mammalian subject if: (a) at least one unique expression signature of said proteomic profiles differs in said test sample relative to said reference sample wherein said unique expression signature of said reference sample proteomic profile comprises information of the expression of at least one of the following: IGFBP-1, Gelsolin precursor, Calgranulin A, Alpha-1-acid glycoprotein 1 precursor, and Alpha-1-antitrypsin precursor; or fragments or naturally occurring variants, and wherein the reference sample proteomic profile is a normal proteomic profile that is indicative of normal birth; or (b) at least one unique expression signature of said proteomic profiles is essentially the same in said test sample relative to said reference sample wherein said unique expression signature of said reference sample proteomic profile comprises information of the expression of at least one of the following: IGFBP-1, Gelsolin precursor, Calgranulin A, Alpha-1-acid glycoprotein 1 precursor, and Alpha-1-antitrypsin precursor; or fragments or naturally occurring variants thereof, and wherein the reference sample proteomic profile is a proteomic profile that has been predetermined to be indicative of pre-term birth.
2. The method of claim 1 wherein said IGFBP-1 fragment comprises SEQ ID NO 4.
3. The method of claim 1 wherein said test sample and said reference sample proteomic profiles further comprise information of the expression of one or more of the following polypeptides: Calgranulin B, Neutrophil gelatinase-associated lipocalin, Annexin II (Lipocortin II), and Complement C3 precursor; or fragments or naturally occurring variants thereof.
4. The method of claim 3 wherein said test sample and said reference sample proteomic profiles further comprise information of the expression of one or more of the following polypeptides: L-plastin (Lymphocyte cytosolic protein 1), Profilin I, Alpha-1-acid glycoprotein 2 precursor, Alpha-1-antichymotrypsin precursor, Ceruloplasmin precursor, Apolipoprotein A-I precursor (Apo-AI), 14-3-3 protein zeta/delta plasma, Vitamin D-binding protein precursor, Serotransferrin, Squamous cell carcinoma antigen 1, 14-3-3 protein sigma (Stratifin), Cystatin A (Stefin A), Fibronectin precursor, Squamous cell carcinoma antigen 2, and Azurocidin; or fragments or naturally occurring variants.
5. The method of claim 4 wherein the proteomic profiles are represented in the form of mass spectra.
6. The method of claim 5 wherein said mammalian subject is a primate.
7. The method of claim 6 wherein said primate is human.
8. The method of claim 1 wherein the biological fluid is amniotic fluid or maternal serum.
9. The method of claim 1 wherein said proteomic profiles comprise information of the expression of at least 10 proteins.
10. The method of claim 1 wherein said proteomic profiles comprise information of the expression of at least 20 proteins.
11. The method of claim 1 wherein said proteomic profiles comprise information of the expression of at least 50 proteins.
12. A method for predicting pre-term birth in a mammalian subject, comprising:
- (1) comparing the proteomic profile of a test sample of a biological fluid with a proteomic profile of a reference sample wherein said test sample proteomic profile and said reference sample proteomic profile comprise information of the expression of IGFBP-1 or fragments or naturally occurring variants thereof, and;
- (2) predicting pre-term birth in said mammalian subject if: (A) at least one unique expression signature of said proteomic profiles differs in said test sample relative to said reference sample, wherein said unique expression signature of said reference sample proteomic profile comprises information of the expression of IGFBP-1 or fragments or naturally occurring variants thereof; and wherein the reference sample proteomic profile is a normal proteomic profile that is indicative of normal birth; or (B) at least one unique expression signature of said proteomic profiles is essentially the same in said test sample relative to said reference sample wherein said unique expression signature of said reference sample proteomic profile comprises information of the expression of IGFBP-1, or fragments or naturally occurring variants thereof and wherein the reference sample proteomic profile is a proteomic profile that has been predetermined to beindicative of pre-term birth.
13. The method of claim 1 wherein said IGFBP-1 fragment comprises SEQ ID NO 4.
14. The method of claim 13 wherein the proteomic profiles are represented in the form of mass spectra.
15. The method of claim 12 wherein said mammalian subject is a primate.
16. The method of claim 15 wherein said primate is human.
17. The method of claim 12 wherein the biological fluid is amniotic fluid or maternal serum.
18. The method of claim 12 wherein said proteomic profiles comprise information of the expression of at least 10 proteins.
19. The method of claim 12 wherein said proteomic profiles comprise information of the expression of at least 20 proteins.
20. The method of claim 12 wherein said proteomic profiles comprise information of the expression of at least 50 proteins.
Type: Application
Filed: Jun 22, 2006
Publication Date: Feb 26, 2009
Inventors: Ron Rosenfeld (Los Altos, CA), Sri Nagalla (Hillsboro, OR), Mike Gravett (Portland, OR)
Application Number: 11/473,797
International Classification: G06F 19/00 (20060101);
