Activation of GPER1 in macrophage ameliorates UUO-induced renal fibrosis
Numerous studies have proven the critical role of macrophages in the renal fibrosis process. Notably, G Protein-coupled Estrogen Receptor 1 (GPER1), a novel estrogen receptor, has been shown to play a ubiquitous role in the regulation of macrophage activities and proinflammatory pathways. However, the precise role of GPER1 in macrophage-mediated renal fibrosis is unknown.  In this study, we aimed to investigate the function of macrophage GPER1 in the UUO-induced renal fibrosis model. Compared to vehicle-treated ovariectomized (OVX) female and male UUO models, we observed that G-1 (GPER1 agonist)-treated OVX female and male UUO mice had fewer renal fibrotic lesions and less M1 and M2 macrophage infiltration in the kidney tissues. Conversely, Gper1 deletion in male UUO mice accelerated renal fibrosis and increased inflammation. In vitro studies also revealed that GPER1 activation reduced M0 macrophage polarization towards M1 and M2 phenotypes. The RNA sequencing analysis and immunoblotting indicated that GPER1 activation was primarily involved in downregulating immune pathways activation and inactivating MAPK pathways.   Tubular epithelial cells co-cultured with G1-pretreated M1 macrophages exhibited fewer injuries and immune activation. In addition, fibroblasts co-cultured with G1-pretreated M2 macrophages showed downregulated extracellular matrix expression.  Overall, this is the first study to demonstrate the effect of GPER1 on macrophage-mediated renal fibrosis via inhibition of M1 and M2 macrophage polarization. These findings indicate that GPER1 may be a promising therapeutic target for the treatment of renal fibrosis. Overall design: To invsetigate the role of GPER1 activation in macrophage,  bone marrow macrophages were isolated and differntiated into M0 macrophages. Then M0 were polarized into M1 or M2 phenotype macrophages stimulated with LPS/INF or IL4, with or without treatment of  GPER1 agonist.  Further, primary tubular epithelial cells or fibroblast  were co-cultured with M1 or M2 macrophages pretreated with G-1 or DMSO. Then the RNA sequencing was performed on Macrophage control, macrophage treated with LPS/INF, macrophages treated with G-1, macrophages treated with G-1 and LPS/INF,  macrophages treated with IL-4, macrophages treated wtih G-1 and IL-4. Tubular epithelial cells co-cultured with LPS/INF treated macrophages and Tubular epithelial cells co-cultured with G-1 and LPS/IFN treated macrophages.