Objective: To compare the expression of interleukin-6 (IL-6) in endometrial and endometriotic cells.
Design: Prospective study.
Setting: Department of Obstetrics and Gynecology, Tottori University Hospital, Yonago, Japan.
Patient(s): Twenty patients who underwent either hysterectomy or laparoscopic surgery.
Intervention(s): Endometrial and endometriotic stromal cells were obtained from normal endometrium and from chocolate cyst linings of the ovary. Peritoneal macrophages were isolated from peritoneal fluids. Cells were cultured in the presence or absence of tumor necrosis factor-alpha.
Main outcome measure(s): Gene expression of IL-6 was examined by Northern blot analysis. Interleukin-6 protein production was examined by immunocytochemical staining and ELISA.
Result(s): A single IL-6 messenger RNA band of approximately 1.3 kilobases was detected in endometriotic stromal cells. Tumor necrosis factor-alpha increased the expression of IL-6 messenger RNA in endometriotic cells in a dose-dependent manner. In endometrial stromal cells, IL-6 messenger RNA signals were much weaker. Endometriotic stromal cells produced significantly larger amounts of IL-6 compared with endometrial stromal cells under basal conditions and after stimulation with tumor necrosis factor-alpha. Interleukin-6 protein was detected in cells isolated from endometriotic tissues by immunocytochemical staining. Interleukin-6 production by cultured macrophages from patients with endometriosis and endometriotic stromal cells was comparable.
Conclusion(s): Altered gene expression and protein secretion of IL-6 in patients with endometriosis may contribute to the pathogenesis of the disease and/or to endometriosis-associated infertility.