PROBLEM: The pro-inflammatory cytokine interleukin (IL)-1β has been shown to stimulate the production of prostaglandins (PG) in gestational tissues. Increased PG synthesis is considered a key step in the initiation of labor both at term and preterm. In this study, IL-1β mRNA in the uterus and gestational tissues of mice during mid to late pregnancy was studied to characterize its tissue specific as well as gestational age expression.
METHOD OF STUDY: Gestational tissues (placenta, decidual cap and fetal membranes), uterus, and cervix were collected from pregnant mice during gestation. Total RNA was isolated and probed for the expression of IL-1β mRNA.
RESULTS: There was a significantly increased expression of IL-1β mRNA in the uterus on day 18 of pregnancy. In the decidual caps, there was increased expression of IL-1β mRNA on day 14 of pregnancy and a decrease in expression with the onset of labor. In the fetal membranes and placenta, IL-1β mRNA expression significantly increased on days 14 and 18 of pregnancy, respectively, and then remained elevated for the duration of pregnancy. In the cervix, there was a decrease in expression with labor onset.
CONCLUSIONS: The increases in IL-1β mRNA in the fetal membranes and placenta late in pregnancy are consistent with a localized, tissue specific inflammatory activation involved in the initiation of parturition.