Regulation of estrogen activity in human endometrium: effect of IL-1beta on steroid sulfatase activity in human endometrial stromal cells

We investigated the effect of interleukin 1beta (IL-1beta) on steroid sulfatase (STS) activity and the expression of STS mRNA in human endometrial stromal cells. Endometrial tissue samples were obtained from patients undergoing hysterectomy to remove uterine fibroids. Stromal cells were isolated from the tissue preparation and cultured. IL-lbeta (1 approximately 100 ng/ml) was added into the culture medium and incubated for 24 h. The expression of STS mRNA was measured by competitive RT-PCR. The addition of IL-lbeta at 10 and 100 ng/ml suppressed STS mRNA expression to 55.2 +/- 12.8% and 25.1 +/- 10.9%, respectively, of the control sample to which no IL-lbeta had been added. STS activity was measured by radiolabelled steroid metabolite using thin layer chromatography, and this activity was also significantly suppressed in response to the administration of IL-lbeta in a dose-dependent manner. When IL-1 receptor antagonist (IL-1ra) was added together with IL-1beta to the culture medium, mRNA expression and STS activity were recovered. The present study is the first to demonstrate IL-1beta regulation of STS activity locally in human endometrium. IL-1beta suppressed mRNA and activity of STS in stromal cell culture. This initial demonstration of IL-1beta regulation of STS implies that IL-1beta may control the steroid microenvironment in human uterine endometrium by reducing biologic action of estrogen.