Interleukin-11 (IL-11) in human endometrium: expression throughout the menstrual cycle and the effects of cytokines on endometrial IL-11 production in vitro.

Interleukin-11 is a member of the IL-6 family of cytokines. Its presence in mouse decidua has been shown and experiments in genetically modified mice have suggested the importance of its receptor in stromal cell decidualization. In this study we used immunocytochemistry to determine expression of IL-11 in human endometrium. The effects of TNFalpha, IL-1alpha and TGFbeta on IL-11 production by epithelial and stromal cells was also investigated. Immunocytochemical staining in sections cut from 19 endometrial biopsies obtained throughout the menstrual cycle showed that IL-11 was expressed in both human endometrial epithelial and stromal cells, with epithelial staining being more intense than that seen in the stromal cells, at all times except the late secretory phase when the intensity was similar. Basal IL-11 production by cultured epithelial cells was greater than basal production by stromal cells. IL-1alpha, TNFalpha and TGFbeta (0.1-10 ng/ml) all caused a concentration-dependent increase in IL-11 production by both epithelial and stromal cells, but stimulated: basal values were greater for stromal than epithelial cells for all three cytokines. This work shows, for the first time, the presence of IL-11 within the human endometrium and that its production is controlled by other cytokines, which are postulated to play a role in implantation. Thus IL-11 may also play an important role in human endometrial function and embryo implantation.