Using proteomic analysis of the human amniotic fluid to identify histologic chorioamnionitis

OBJECTIVE: To estimate the relationship between histologic chorioamnionitis and four amniotic fluid proteomic biomarkers characteristic of inflammation (defensins 2 and 1, calgranulins C and A). METHODS: One hundred fifty-eight women with singleton pregnancies had a clinically indicated amniocentesis to rule out inflammation and infection in the context of preterm labor or preterm premature rupture of membranes. A proteomic fingerprint (Mass Restricted score) was generated from amniotic fluid using surface-enhanced laser desorption ionization time-of-flight mass spectrometry. The Mass Restricted score ranges from 0 to 4 (none to all four biomarkers present) in direct relationship with severity of intra-amniotic inflammation. Presence or absence of biomarkers was analyzed in relationship to placental pathology. Criteria for severity of histologic chorioamnionitis were 3 stages and 4 grades of inflammation of the amnion, choriodecidua and chorionic plate. RESULTS: The prevalence of histologic chorioamnionitis was 64% (stage I 12 /0, stage II 16%, and stage III 37%). The Mass Restricted score significantly correlated with stages of histologic chorioamnionitis (r=0.539, P<.001), grades of choriodeciduitis (r=0.465, P<.001), and amnionitis (r=0.536, P<.001). African-American women were overrepresented in the group with severe inflammation (Mass Restricted score 3-4, P=.022). Of the four biomarkers of the Mass Restricted score, calgranulin C had the strongest relationship with presence of stage III chorioamnionitis, independent of race, amniocentesis-to-delivery interval, and gestational age. CONCLUSION: Proteomic analysis of amniotic fluid provides an opportunity for early recognition of histologic chorioamnionitis. This methodology may in the future identify candidates for antenatal therapeutic interventions.