Expression of interleukin (IL)-11 receptor by the human endometrium in vivo and effects of IL-11, IL-6 and LIF on the production of MMP and cytokines by human endometrial cells in vitro

Interleukin (IL)-6, leukaemia inhibitory factor (LIF) and IL-11 belong to the same family of cytokines whose receptors utilize gp130 as the signalling molecule. We have investigated the expression of the IL-11 receptor, IL-11R, protein in the human endometrium in vivo and the effects of IL-6, LIF and IL-11 on the production of metalloproteinases (MMPs) and cytokines by cultured endometrial epithelial and stromal cells. Immunostaining showed that IL-11R was expressed in both epithelial and stromal cells, with epithelial staining being more intense than stromal staining and little variation in staining in either compartment throughout the cycle. Incubation of both stromal and epithelial cells with IL-6, LIF and IL-11 had no effect on MMP-2, -7, -9, transforming growth factor (TGF)ß or IL-1ß production or cell growth. IL-6 and LIF also had no effect on tumour necrosis factor (TNF) production, but IL-11 caused a dose-dependent decrease in TNF production by epithelial cells. IL-6 receptor, LIF receptor and gp130 were all expressed by cultured stromal and epithelial cells, showing that the lack of effect is not due to lack of expression of the receptor components. The results show that although IL-6, LIF and IL-11 signal through the same molecule, they may have different effects in endometrial cells, suggesting the activation of different signalling pathways, which may ultimately be important in the control of endometrial function.