Interleukin-1 (IL-1) regulation of human endometrial function: presence of IL-1 receptor correlates with IL-1-stimulated prostaglandin E2 production.

Previous studies suggest that prostaglandin E2 (PGE2) is important in normal endometrial function and that it may be involved in certain uterine dysfunctions. In this study, the ability of the purified E. coli-derived recombinant interleukin-1 alpha (rIL-1 alpha) to regulate the production of PGE2 by the endometrial epithelium is investigated. PGE2 levels determined by the RIA consistently increase upon incubation of cultured glandular epithelial cells with rIL-1 alpha. A significant increase is obtained with 17 and 170 ng/L rIL-1 alpha. A maximal effect is obtained within 24 h of incubation with rIL-1 alpha. In the seven endometria evaluated, rIL-1 alpha increases PGE2 synthesis in all cases, but the maximal increase relative to the basal levels varies between 2- to 10-fold for a given preparation. Vibratome sections retaining the integrity of the endometrial tissue also show an increased PGE2 synthesis in response to rIL-1 alpha. rIL-1 alpha-stimulated PGE2 production is blocked by the addition of a neutralizing antibody to rIL-1 alpha. In addition, indomethacin, a cyclooxygenase inhibitor, suppresses both rIL-1 alpha-induced and basal PGE2 synthesis. Experiments using radioiodinated rIL-1 alpha reveal that the membranes prepared from human endometrial epithelium possess high affinity receptors for IL-1, suggesting that IL-1 regulates PGE2 synthesis by binding to this receptor site. The expression of IL-1 receptors and the ability to modulate PGE2 production by IL-1 in endometrial epithelium suggest that IL-1 may play a significant role in human uterine function via modulation of PGE2 production.