Introduction:
In this study, we studied anti-IL-6 antibodies to treat endometriosis (EMS) by balancing Th17/Treg cells, providing a new basis for EMS research and treatment.

Material and methods:
The rat EMS model was constructed to study the effect of anti-IL-6 on EMS. HE staining was performed to observe the lesions of the endometrium in rats. We have used anti-IL-6 to treat EMS rats. Then ELISA was used to measure the inflammatory factors IL-6, TGF-β and hormone estrogen levels in the rat serum. qRT-PCR and Western blot were used to measure estrogen receptor protein and apoptosis protein levels. Th17/Treg and CD163+/CD86+ ratios were determined by flow cytometry. CD34+ and CD163+ were measured by immunohistochemistry. TUNEL was performed to detect apoptosis in EMS lesions.

Results:
The elevated levels of IL-6, TGF-β and estrogen in EMS rats indicated successful modeling. The ratio of Th17/Treg was imbalanced and raised. The ratio of Th17/Treg in anti-IL-6 rats recovered. The expression of FOXP3 in anti-IL-6 rats increased, and ROR-γt expression was suppressed. Anti-IL-6 could increase the apoptosis of the cells in the lesion. The size of the lesion was reduced. The expression of VEGF in the microenvironment of the lesions of EMS rats decreased.

Conclusions:
IL-6 regulated Th17/Treg cells to restore the local microenvironment of EMS. Anti-IL-6 could regulate the immune microenvironment of EMS rats to alleviate the progression of EMS disease.