Interleukin-1 inhibits in vitro decidualization of human endometrial stromal cells

Interleukin-1 (IL-1), a critical cytokine for the initiation of the immune response to infection or antigenic challenge, is known to also possess a variety of biological functions outside the immune system. We examined whether IL-1 could affect the decidualization of human endometrial stromal cells (ESC), a conspicuous part in the process of implantation, by assessing PRL production and morphological transformation in an in vitro system. Purified human ESC were cultured in the presence of progesterone (P) with or without the addition of IL-1. IL-1 markedly suppressed the induction of PRL production by P in a dose-dependent manner. The morphological decidualization of ESC in response to P was also inhibited by IL-1. This report demonstrates for the first time the possibility that IL-1 blocks decidualization, the functional differentiation of human endometrial stromal cells in response to ovarian steroids.