Expression of interleukin-1beta mRNA in murine uterine and gestational tissues: relationship with gestational age.

PROBLEM: The pro-inflammatory cytokine interleukin (IL)-1beta 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-1beta 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-1beta mRNA. RESULTS: There was a significantly increased expression of IL-1beta mRNA in the uterus on day 18 of pregnancy. In the decidual caps, there was increased expression of IL-1beta mRNA on day 14 of pregnancy and a decrease in expression with the onset of labor. In the fetal membranes and placenta, IL-1beta 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-1beta 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.