Benzo[b]fluoranthene is involved in idiopathic membranous nephropathy by inducing podocyte injury.

The incidence of idiopathic membranous nephropathy (IMN) has been increasing in recent years and is closely correlated with fine particulate matter particulate matter (PM) 2.5. Thus, the relationship between polycyclic aromatic hydrocarbons (PAHs), one of the main components of PM2.5, and IMN should be explored. Patients with IMN and healthy control (HC) individuals were screened, and the concentrations and clinical indicators of blood PAHs were detected in these two groups for statistical analysis. Immortalized mouse podocyte cells were treated with 6.25, 12.5, and 25 μg/mL Benzo[b]fluoranthene (BbF) for 72 h. The cell morphology was observed, and the expressions of nephrin and synaptopodin (Synpo) were detected. On days 0 and 2, 1.25 mg/kg BbF was intratracheally administered to the rats. The rats were sacrificed on day 0, day 3, day 7, and day 14. The glomerulus was observed under a microscope, and the nephrin expression was detected. Compared with the HC group, the total concentration of PAHs in the IMN group was significantly increased (P < 0.001), and the between-group diference was -3.031 μg/mL (95% confidence interval, -3.739 to -2.324). The total concentration of PAHs in the IMN group was significantly negatively correlated with total protein (TP) and albumin (ALB) and significantly positively correlated with β2 microglobulin (β2-MG) and 24-hour urine TP (24hTP). Among them, BbF was not only negatively correlated with TP and ALB but also positively correlated with cystatin C, β2-MG, and 24hTP and was positively correlated with anti-phospholipase A2 receptor (P < 0.05). In cell experiments, the cell morphology became irregular, the cytoplasm started to shrink, the number of cells decreased with increasing BbF concentration, and the expressions of nephrin and Synpo decreased with increasing BbF concentration. In animal experiments, glomeruli had marked inflammatory cell infiltration in hematoxylin and eosin staining, mesangial cell proliferation and increased mesangial matrix in periodic acid-Schif staining, and deposition of a small number of immune complexes in Masson staining over time, and the nephrin expression gradually decreased. This study showed that the total concentration of PAHs in the blood of patients with IMN significantly increased, and BbF is significantly correlated with the disease severity of IMN, suggesting that PAHs are correlated with IMN occurrence and development and may play a certain role in IMN.