Inducers of G-protein coupled estrogen receptor (GPER) in endometriosis: potential implications for macrophages and follicle maturation

Endometriosis is an estrogen dependent chronic inflammation and thus a condition of stress. Though the G-protein coupled estrogen receptor (GPER) has been shown to be up-regulated in ovarian endometriosis, insights involved in inducing this receptor expression are largely elusive. Therefore, this study investigated whether stress-related factors (ACTH, prednisolone) or inflammatory factors (IL-1β, TNFα, and PGE2) factors may affect GPER. To further link GPER to endometriosis pathophysiology it was tracked in macrophages and follicles of endometriotic ovaries. This study found GPER expression to be modulated by stress-related hormones as well as inflammation and to be up-regulated in endometriosis-associated macrophages. At the same time, follicles of ovaries affected by endometriosis presented significantly reduced GPER positivity when compared to controls, suggesting a possible way by which endometriosis may affect folliculogenesis. The multiple roles of GPER as presented herein make it a promising future candidate for targeted molecular endometriosis treatment.