266. Supressor of cytokine signalling 3 regulates IL-11 induced human endometrial stromal cell decidualization

Abstract

Decidualization of endometrial stromal cells is critical for embryo implantation and establishment of pregnancy. Locally produced cytokines such as interleukin (IL)-11 enhance decidualization of human endometrial stromal cells (HESC). IL-11 signaling is negatively regulated by suppressor of cytokine signaling (SOCS) proteins. IL-11 stimulates SOCS3 in human pituitary cells. The aim of this study was to examine the role of SOCS3 on IL-11 induced HESC decidualization. Decidualization of HESC was assessed using an in vitro model in which estrogen (E)+progesterone (P) or cAMP was administered for 8 days to cells. Medium was collected for prolactin (PRL) assay (a decidual marker). Cellular protein was extracted for Western analysis and cellular RNA for real-time RT-PCR analysis. SOCS3 was overexpressed in HESC cells and the effect on decidualization assessed. HESC treated with E+P or cAMP secreted PRL from day 6. Treatment of HESC with E+P or cAMP increased the abundance of SOCS3 protein, coinciding with an increase in PRL secretion. cAMP maximally stimulated SOCS3 protein and mRNA during decidualization. Antiprogestin (onapristone) added to E+P or cAMP treated cells at day 6 reduced PRL secretion but had no influence on SOCS3 abundance suggesting that SOCS3 protein was not regulated via the P-receptor pathway. Addition of IL-11 to HESC increased SOCS3 abundance from 1 h. SOCS3 abundance returned to control levels following treatment of cells with IL-11 and IL-11 neutralising antibody. SOCS3 overexpression in HESC treated with cAMP reduced PRL secretion compared to mock- or non-transfected HESC. Furthermore, IL-11 mediated decidualization was diminished by SOCS3 overexpression. We have demonstrated for the first time that SOCS3 regulates IL-11 induced decidualization and that SOCS3 overexpression in HESC disrupts decidualization. This knowledge is important in understanding the mechanisms by which IL-11 promotes decidualization of HESC and thus the formation of decidua, an essential component of a functional placenta.