Dysregulated biomarkers induce distinct pathways in preterm birth.

OBJECTIVE: To document racial disparity in biomarker concentrations in maternal/fetal plasma and amniotic fluid between African Americans and European Americans with spontaneous preterm birth (PTB; cases) and normal term birth (controls), and their contribution to distinct pathophysiological pathways of PTB. DESIGN: Nested case-control study. SETTING: The Perinatal Research Center, Nashville, Tennessee, USA. SAMPLE: Maternal and fetal plasma and amniotic fluid samples were collected from 105 cases (59 African American and 46 European American) and 86 controls (40 African American and 46 European American). METHODS: Thirty-six biomarkers were analysed using the protein microarray approach. MAIN OUTCOME MEASURES: Differences in biomarker concentrations between cases and controls of different races in maternal, fetal and intra-amniotic compartments, and the risk of PTB. Dysregulated biomarker-induced PTB pathways associated with PTB in each race were determined using ingenuity pathway analysis (IPA). RESULTS: Racial disparity was observed in biomarker concentrations in each compartment between cases and controls: amniotic fluid, IL8 and MIP1α differed between case and controls in European Americans, whereas ANGPT2, Eotaxin, ICAM-1, IL-1ß, IL1RA, RANTES and TNFα differed between case and controls in African Americans. In both races the FAS ligand, MCP-3 and TNFR-I differed between cases and controls. For fetal plasma, ANGPT2, Eotaxin, FGF basic, ICAM-1, IGF-I, IL10, IL-1ß, IL2, IP10 KGF, MCP-3, MIP1α, PDGF-BB, TGFα, TGFß1, TIMP1, TNFα, TNFR-I, TNFR-II and VEGF differed between cases and controls in European Americans, whereas only MMP7 differed between cases and controls in African Americans. IL-8 differed between cases and controls in both races. For maternal plasma, IL1RA, MMP7 and VEGF differed between cases and controls in European Americans, whereas ANGPT2, FGF basic, IL-1ß, IL5, IL6R, KGF, MCP-3, MIP1α, TIMP1 and TNFα differed between cases and controls in African Americans. ANG, IL8 and TNFR-I differed between cases and controls in both races. CONCLUSIONS: We conclude that: (1) biomarker concentrations in maternal, fetal and intra-amniotic compartments differ between cases and controls; (2) there is racial disparity in the biomarker profile in each of the compartments; (3) substantial numbers of dysregulated fetal plasma biomarkers contribute to PTB in European Americans, whereas maternal plasma biomarkers contribute to PTB in African Americans; and (4) both inflammation and haematological functions are associated with PTB in European Americans, but maternal proinflammatory changes dominate PTB in African Americans. Biomarker analyses document racial disparity and the distinct pathophysiological contributions from different compartments that can determine pregnancy outcome.

Cigarette smoke induces oxidative stress and apoptosis in normal term fetal membranes.

Cigarette smoking and bacterial infections are two major risk factors associated with preterm prelabor rupture of membranes (pPROM). We hypothesized that exposure of fetal membranes to cigarette smoke extracts might induce oxidative stress (OS) and fetal membrane apoptosis, culminating in an alternate pathway to that commonly activated by infection. To test this, we characterized the production of prostanoids and biomarkers of apoptosis in normal term human fetal membrane explant cultures. Fetal membrane explants collected at term (from cesarean deliveries, not in labor) were stimulated with cigarette smoke extract (CSE) for 24 h. Two classes of prostanoids, F2-Isoprostane (F2-IsoP), a marker of OS and PGF2α, a classical uterotonin, were measured by gas chromatography/mass spectrometry. Western blot analyses of tissue lysates were performed to quantify the anti-apoptotic protein Bcl2 and actin (as a control). Fetal membrane apoptosis was detected by immunohistochemistry for active caspase 3 and confirmed by TUNEL staining for nuclear fragmentation. CSE exposure resulted in significantly more F2-IsoP production from fetal membranes (242.8 ± 79.3 pg/ml/mg of total membrane protein) compared to unstimulated controls (131.5 ± 53.1 pg/ml/mg; p < 0.0001). By contrast, PGF2α was not different in CSE vs. controls (1083 ± 527 vs. 1136 ± 835 pg/ml/mg of protein; p = 0.80). CSE-exposed tissues demonstrated a dose-dependent decrease in Bcl2 expression and increases in active caspase 3 and nuclear fragmentation in both amnion and chorion cells compared to controls. In summary, fetal membranes exposed to CSE manifest evidence of OS and apoptosis. The differential pattern of prostanoid production observed in this study supports the hypothesis that an alternate non-inflammatory pathway mediated by OS and apoptosis in pPROM may promote proteolysis resulting in membrane weakening and rupture.