Human endometrial interleukin-6 (IL-6): In vivo messenger ribonucleic acid expression, in vitro protein production, and stimulation thereof by IL-1 beta

Objective: To investigate human endometrial interleukin-6 (IL-6) expression an Design: Prospective. Setting: Academic medical center. Patient(s): Endometrial biopsy specimens from normal volunteers (n = 20) at four specific menstrual stages were used for in vivo study. Endometrial specimens for in vitro study were obtained from patients (n = 19) undergoing gynecologic surgery. Intervention(s): Time and dose-response treatment of endometria with IL-1 beta in tissue culture. Main Outcome Measure(s): In vivo IL-6 messenger RNA expression by Northern analysis and in vitro endometrial IL-6 protein production by assay of the conditioned media. Result(s): Midsecretory and late secretory phase endometria expressed more IL-6 messenger RNA than late proliferative phase endometria in vivo. Similarly in vitro, in pg/mg endometrium per hour secretory endometria IL-6 protein production, 25.7 +/- 7.1 (mean +/- SEM), exceeded that of proliferative endometria, 4.7 +/- 1.0. With IL-1 beta treatment, secretory endometria IL-6 protein production exceeded that of proliferative endometria. Interleukin-1 beta stimulated endometrial IL-6 protein production in time- and dose-dependent manners. Conclusion(s): Human endometrial IL-6 expression varies with the menstrual cycle, occurs more highly in secretory endometria, and in vitro is stimulated by interleukin-1 beta. Human endometrial IL-6 may therefore mediate some actions of IL-1 beta involving the endometrium and trophoblast.