Objective The purpose of this study was to compare intraamniotic inflammation vs microbial invasion of the amniotic cavity (MIAC) as predictors of adverse outcome in preterm labor with intact ...membranes. Study Design Interleukin-6 (IL-6) was measured in prospectively collected amniotic fluid from 305 women with preterm labor. MIAC was defined by amniotic fluid culture and/or detection of microbial 16S ribosomal DNA. Cases were categorized into 5 groups: infection (MIAC; IL-6, ≥11.3 ng/mL); severe inflammation (no MIAC; IL-6, ≥11.3 ng/mL); mild inflammation (no MIAC; IL-6, 2.6-11.2 ng/mL); colonization (MIAC; IL-6, <2.6 ng/mL); negative (no MIAC; IL-6, <2.6 ng/mL). Results The infection (n = 27) and severe inflammation (n = 36) groups had similar latency (median, <1 day and 2 days, respectively) and similar rates of composite perinatal morbidity and mortality (81% and 72%, respectively). The colonization (n = 4) and negative (n = 195) groups had similar outcomes (median latency, 23.5 and 25 days; composite morbidity and mortality rates, 21% and 25%, respectively). The mild inflammation (n = 47) groups had outcomes that were intermediate to the severe inflammation and negative groups (median latency, 7 days; composite morbidity and mortality rates, 53%). In logistic regression adjusting for gestational age at enrollment, IL-6 ≥11.3 and 2.6-11.2 ng/mL, but not MIAC, were associated significantly with composite morbidity and mortality rates (odds ratio OR, 4.9; 95% confidence interval CI, 2.2–11.2, OR, 3.1; 95% CI, 1.5–6.4, and OR, 1.8; 95% CI, 0.6–5.5, respectively). Conclusion We confirmed previous reports that intraamniotic inflammation is associated with adverse perinatal outcomes whether or not intraamniotic microbes are detected. Colonization without inflammation appears relatively benign. Intraamniotic inflammation is not simply present or absent but also has degrees of severity that correlate with adverse outcomes. We propose the designation amniotic inflammatory response syndrome to denote the adverse outcomes that are associated with intraamniotic inflammation.
Objective Senescence is an important biological phenomenon involved in both physiologic and pathologic processes. We propose that chorioamniotic membrane senescence is a mechanism associated with ...human parturition. The present study was conducted to explore the association between senescence and normal term parturition by examining the morphologic and biochemical evidences in chorioamniotic membranes. Study Design Chorioamniotic membranes were collected from normal term deliveries; group 1: term labor and group 2: term, not in labor. Senescence-related morphologic changes were determined by transmission electron microscopy and biochemical changes were studied by senescence-associated (SA) β-galactosidase staining. Amniotic fluid samples collected from both term labor and term not in labor were analyzed for 14 SA secretory phenotype (SASP) markers. Results Morphologic evidence of cellular senescence (enlarged cells and organelles) and a higher number of SA β-galactosidase-stained amnion and chorion cells were observed in chorioamniotic membranes obtained from women in labor at term, when compared to term not in labor. The concentration of proinflammatory SASP markers (granulocyte macrophage colony-stimulating factor, interleukin-6 and -8) was significantly higher in the amniotic fluid of women in labor at term than women not in labor. In contrast, SASP factors that protect against cell death (eotaxin-1, soluble Fas ligand, osteoprotegerin, and intercellular adhesion molecule-1) were significantly lower in the amniotic fluid samples from term labor. Conclusion Morphologic and biochemical features of senescence were more frequent in chorioamniotic membranes from women who experienced term labor. Senescence of chorioamniotic membranes were also associated with amniotic fluid SASP markers.
Objective Microbial invasion of the amniotic cavity (MIAC) is common in early preterm labor and is associated with maternal and neonatal infectious morbidity. MIAC is usually occult and is reliably ...detected only with amniocentesis. We sought to develop a noninvasive test to predict MIAC based on protein biomarkers in cervicovaginal fluid (CVF) in a cohort of women with preterm labor (phase 1) and to validate the test in an independent cohort (phase 2). Study Design This was a prospective study of women with preterm labor who had amniocentesis to screen for MIAC. MIAC was defined by positive culture and/or 16S ribosomal DNA results. Nine candidate CVF proteins were analyzed by enzyme-linked immunosorbent assay. Logistic regression was used to identify combinations of up to 3 proteins that could accurately classify the phase 1 cohort (N = 108) into those with or without MIAC. The best models, selected by area under the curve (AUC) of the receiver operating characteristic curve in phase 1, included various combinations of interleukin (IL)-6, chemokine (C-X-C motif) ligand 1 (CXCL1), alpha fetoprotein, and insulin-like growth factor binding protein-1. Model performance was then tested in the phase 2 cohort (N = 306). Results MIAC was present in 15% of cases in phase 1 and 9% in phase 2. A 3-marker CVF model using IL-6 plus CXCL1 plus insulin-like growth factor binding protein-1 had AUC 0.87 in phase 1 and 0.78 in phase 2. Two-marker models using IL-6 plus CXCL1 or alpha fetoprotein plus CXCL1 performed similarly in phase 2 (AUC 0.78 and 0.75, respectively), but were not superior to CVF IL-6 alone (AUC 0.80). A cutoff value of CVF IL-6 ≥463 pg/mL (which had 81% sensitivity in phase 1) predicted MIAC in phase 2 with sensitivity 79%, specificity 78%, positive predictive value 38%, and negative predictive value 97%. Conclusion High levels of IL-6 in CVF are strongly associated with MIAC. If developed into a bedside test or rapid laboratory assay, cervicovaginal IL-6 might be useful in selecting patients in whom the probability of MIAC is high enough to warrant amniocentesis or transfer to a higher level of care. Such a test might also guide selection of potential subjects for treatment trials.
Spontaneous preterm birth, caused by preterm labor (contractions before 37 weeks' gestation) or preterm premature rupture of the membranes (pPROM) (membrane rupture before the onset of labor) or both ...account for ∼80% of preterm deliveries. pPROM is associated with 30–40% of preterm deliveries and the incidence of pPROM has increased in the past decade. The question we address here is why some women experience pPROM and some experience preterm labor with no rupture of membranes (ROM) when the etiologic factors associated with both these pathologic complications are the same. To date, studies had evaluated the markers that are commonly elevated in both preterm labor and pPROM. A better understanding of the similarities and differences between the biomolecular pathways leading to each of these conditions may open new avenues for research and intervention. In this chapter we review the role of inflammatory mediators (cytokines and matrix metalloproteinases), and programmed cell death (apoptosis) in preterm labor with no ROM and preterm labor with pPROM to delineate the differences in pathways between the two conditions.
Objective The objective of the study was to study the genetic risk factors of spontaneous preterm birth (PTB) in African Americans. Study Design Case-control analyses were performed using maternal ...and fetal deoxyribonucleic acid from 279 African American birth events (82 PTB and 197 term) and 1432 single-nucleotide polymorphisms from 130 candidate genes. Single-locus association and haplotype analyses were performed. Results The most significant associations were in the maternal interleukin (IL)-15 (rs10833, allele P = 2.91 × 10−4 , genotype P = 2.00 × 10−3 ) gene and the fetal IL-2 receptor B (IL-2RB) (rs84460, allele P = 1.37 × 10−4 , genotype P = 6.29 × 10−4 ) gene. The best models for these markers were additive (rs10833, odds ratio OR, 0.30; 95% confidence interval CI, 0.14-0.62; P = 1.0 × 10−3 ; rs84460, OR, 2.32; 95% CI, 1.47-3.67; P < 1.0 × 10−3 ). The largest number of significant associations was found in genes related to infection and inflammation. There were overall a larger number of significant associations in infants than in mothers. Conclusion These results support a strong role for genes involved in infection and inflammation in the pathogenesis of PTB, particularly IL-12 and IL-12RB, and indicate that in African Americans there may be complementarity of maternal and fetal genetic risks for PTB.
Objective The purpose of this study was to document distinct pathways that are initiated by lipopolysaccharide and cigarette smoke stimulation of normal term fetal membranes. Study Design Fetal ...membranes from nonsmoking women at term, not in labor, from cesarean deliveries were placed in an organ explant system and stimulated with cigarette smoke extracts (CSEs), lipopolysaccharide, or lipopolysaccharide + CSE. Media were assayed for an interleukin (IL)-1β, -1 receptor antagonist, -6, -8, -10, tumor necrosis factor α, soluble tumor necrosis factor receptors 1 and 2, and matrix metalloproteinases 1, 2, 3, 8, 9, and 12. Tissue homogenates were assayed for apoptotic markers (p53, caspase 3 activity, and cleaved poly ADP-ribose polymerase-1). Results Lipopolysaccharide stimulation resulted in higher cytokine and matrix metalloproteinase concentrations, whereas it was lower after CSE and CSE + lipopolysaccharide stimulations, compared with control specimens. Apoptotic factors were several folds higher after CSE or CSE + lipopolysaccharide stimulation, compared with control specimens or lipopolysaccharide stimulations. Conclusion Cigarette smoke showed immunoinhibitory properties that potentially were mediated by apoptosis and lipopolysaccharide-induced proinflammatory response. This study demonstrated 2 independent pathophysiologic pathways that may alter pregnancy outcome.
Objective This study examined the differences in the inflammatory cytokine interleukin (IL)-6 and the immunoinhibitory cytokine IL-10 in the amniotic fluid of black and white women in spontaneous ...preterm birth. Methods In this study, 321 amniotic fluids from cases (preterm birth 36 or fewer weeks’ gestation) and controls (normal term delivery longer than 37 weeks’ gestation) were collected (147 cases 49 blacks and 98 whites and 174 controls 85 blacks and 89 whites) at the time of active labor. IL-6 and IL-10 concentrations were measured by immunoassays. Using normal-term delivery as controls, logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CIs) for preterm birth. Results A significant difference in IL-6 concentration was observed in white cases (cases: 3773 pg/mL; controls: 1682 pg/mL; P = .0003), compared with controls, but not in blacks (cases: 2042 pg/mL; controls: 2366 pg/mL; P = .6). In a combined multivariable analysis, when the highest and the lowest quartiles of IL-6 were compared in whites, the ORs (95% CI) for preterm birth across quartiles were 1.74 (0.62-4.88), 1.09 (0.39-3.02), and 5.68 (2.15-15.0). No such association was found in blacks. IL-10 concentration was not different between cases and controls in either race. Conclusions Race-specific associations exist between IL-6 but not IL-10 concentration and preterm birth. Elevated IL-6 concentrations are associated with preterm birth in whites but not blacks.
Objective Preterm birth rate in the United States is higher in blacks than whites. It has been hypothesized that a differential inflammatory response may explain this disparity. The objective of this ...study is to examine the inflammatory cytokine, tumor necrosis factor (TNF)-α and soluble TNF receptor concentrations (sTNFR1 and sTNFR2) in the amniotic fluid of black and white women at delivery. Study Design Amniotic fluid samples were collected during active labor from 158 cases (preterm births, gestational age 220/7 weeks to 360/7 weeks, 52 black and 106 white) and 175 controls (term births, gestational age 370/7 weeks to 420/7 weeks, 87 black and 88 white) at Centennial Women's Hospital, Nashville, TN. Amniotic fluid TNF-α, sTNFR1, and sTNFR2 concentrations and the molar ratios of TNF-α to its receptors were compared between cases and controls within each racial group. Results Median TNF-α concentration was associated with preterm birth when whites and blacks were analyzed together, with cases having higher values (191.5 pg/mL) than controls (68.9 pg/mL; P < .001). There were no significant associations with sTNFR1 or sTNFR2 concentrations between cases (2409.4 and 2934.3 pg/mL, respectively) and controls (2759.9 and 3084.1 pg/mL, respectively) when the racial groups were analyzed together ( P = .08, P = .4, respectively). Black cases associated with higher TNF-α concentrations (1287.0 pg/mL in cases and 67.3 pg/mL in controls; P < .001). In whites there was no association between TNF-α and preterm birth ( P = .3). The molar ratio of TNF-α/total sTNFR (R1 plus R2) associated with higher TNF-α in black cases, compared with black controls ( P < .001). There was no significant association between white cases and controls for ligand receptor ratios ( P = .3). Conclusion The TNF-α/sTNFR profile in pregnancy differs between racial groups, suggesting a difference in bioavailability of TNF-α. The larger molar ratio of TNF-α/sTNFR in black cases may be indicative of a TNF-α mediated pathological process of preterm birth in blacks but not in whites.
Objective To understand the differences in genetic interactions among tumor necrosis factor-alpha, interleukin-6 and their receptor gene variants between black and white patients in spontaneous ...preterm birth. Study Design Maternal and fetal DNA (n = 1195) were collected from cases (preterm birth < 36 weeks' gestation; n = 448), controls (> 37 weeks' gestation; n = 747), and genotyped for single nucleotide polymorphisms in tumor necrosis factor-alpha, tumor necrosis factor receptor 1, and tumor necrosis factor receptor 2, interleukin-6, and interleukin-6 receptor loci. Multifactor dimensionality reduction analysis was used to test all single and multilocus combinations for the ability to predict pregnancy outcome. Results In white patients, multilocus interactions in maternal DNA between single nucleotide polymorphisms at −7227 (interleukin-6), 22,215 (interleuki-6 receptor) and −3448 (tumor necrosis factor-alpha) was predictive of approximately 59.1% ( P < .02; odds ratio, 2.3 95% confidence interval = 1.6-3.4) of pregnancy outcome. In white fetal DNA and black maternal DNA, no significant interactive models were observed. In black patients, the best epistatic model was in fetal DNA between single nucleotide polymorphisms at 17,691 (tumor necrosis factor-receptor 1) and at −3448 (tumor necrosis factor-alpha) and was predictive of pregnancy outcome 68.3% of the time ( P < .01; odds ratio, 5.0 95% confidence interval = 2.6-9.6). Conclusion Analyses of multilocus interactions found/associated different models in black and white patients in both maternal and fetal DNA with preterm birth as outcome. Significant maternal-fetal interactions were not detected in either race.
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