Caprine endometrial stromal cells modulate the effects of steroid hormones on cytokine secretion by endometrial epithelial cells in vitro.

The main purpose of this study was to examine the effects of 17β-estradiol (E(2)) and progesterone (P(4)) on cytokine secretion by caprine endometrial epithelial cells (EEC) in vitro. Epithelial cells grown alone or in co-culture with stromal cells (ESC) were treated with E(2) or P(4), or both. Homogeneity of the endometrial cell populations was ascertained immunocytochemically. The quantities of cytokines secreted in this system were assessed by ELISA and their protein expression by Western blot. The exposure of EEC to P(4) alone or in combination with E(2) significantly increased the amount of TGF-β1, TNF-α and IL-18 secretion, whereas E(2) had no effect on the synthesis of these cytokines. When epithelial cells were co-cultured with ESC, the secretion of TGF-β1, TNF-α and IL-18 by EEC significantly increased compared to that by EEC alone. However, the treatment with both steroids decreased the secretion of TNF-α, IL-18 and TGF-β1 by EEC in the presence of ESC. In contrast to TGF-β1, TNF-α and IL-18, the secretion of leukemia inhibitory factor (LIF) by EEC was not affected by E(2) and/or P(4) either directly or indirectly. The present results indicate that the interactions between caprine endometrial stromal and epithelial cells can modulate the secretion of TGF-β1, TNF-α and IL-18 by EEC exposed to E(2) and/or P(4)in vitro.