Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL), TRAIL Receptors, and the Soluble Receptor Osteoprotegerin in Human Gestational Membranes and Amniotic Fluid during Pregnancy and Labor at Term and Preterm

We have studied TNF-related apoptosis-inducing ligand (TRAIL) and its membrane-bound (R1–R4) and soluble receptors [osteoprotegerin (OPG)] in gestational membranes to assess their significance in preterm parturition and premature rupture of membranes (PROM). TRAIL was detected by ELISA in extracts of term choriodecidual (but not amnion) tissues and explant-conditioned media. Concentrations of OPG (determined using ELISA) in gestational membranes were 20- to 50-fold greater than those of TRAIL. Median OPG concentrations in amniotic fluid (AF) at 15–17 wk gestation were similar to those at term before and during labor, whereas levels in pregnancies sampled preterm were significantly elevated. OPG levels in AF from women with preterm PROM were similar to those from women in preterm labor. In contrast, in pooled AF samples (n = 23–33), TRAIL concentrations at term with and without labor were elevated compared with samples from preterm deliveries. TRAIL-R3 and -R4 decoy receptors were detected in term amnion a...