Epigenetically Regulated NOX4/NRF2 Axis Mediates PM2.5‐Induced Ferroptosis and Inflammatory Response in Membranous Nephropathy

This study aims to explore the involvement and mechanism of ferroptosis in particulate matter 2.5 (PM2.5)-induced membranous nephropathy (MN) progression. A cationic bovine serum albumin (cBSA)-induced mouse model of MN was established, followed by PM2.5 exposure. Renal injury was assessed using hematological indicators, hematoxylin-eosin staining, and periodic acid-Schiff staining. Levels of inflammatory factors and ferroptosis indicators were assessed by enzyme-linked immunosorbent assay and western blot. An in vitro MN-like model was created by stimulating differentiated MPC5 podocytes with puromycin aminonucleoside (PAN), followed by PM2.5 treatment. DNA methylation levels were determined using quantitative methylation-specific polymerase chain reaction. Podocytes were pretreated with GKT137831 or ferrostatin-1 for in vitro rescue experiments. PM2.5 exposure significantly aggravated renal injury in cBSA-induced MN mice, as indicated by increased levels of urinary total protein, serum creatinine, and blood urea nitrogen; the deposition of IgG and C3; and histopathological alterations. Furthermore, PM2.5 increased levels of ferroptosis and inflammation in the renal tissues of cBSA-induced MN mice, accompanied by the activation of the NOX4/NRF2 axis. In PAN and PM2.5 co-treated MPC5 cells, NOX4 expression was elevated, whereas its methylation level was reduced. Overexpression of DNMT1 reversed the PM2.5-induced suppression of NOX4 methylation. Notably, pretreatment with GKT137831 or ferrostatin-1 attenuated the PM2.5-mediated reduction in cell viability and prevented the activation of ferroptosis and pro-inflammatory phenotypes in PAN-stimulated MPC5 cells. In conclusion, PM2.5 promotes ferroptosis and inflammation through an epigenetically regulated NOX4/NRF2 axis, thereby exacerbating renal injury in MN.