Automobile exhaust-derived PM2.5 induces blood-testis barrier damage through ROS-MAPK-Nrf2 pathway in sertoli cells of rats

Particulate matter with an aerodynamic diameter of less than 2.5 μm (PM2.5) derived from automobile exhaust can lead to serious male spermatogenesis dysfunction, but its specific molecular mechanism is unclear. In this experiment, we focused on the blood-testis barriers (BTB) and explored the intracellular mechanisms underlying the fertility toxicity of PM2.5 originating from automobile exhaust in the primary cultured Sertoli cells(SCs) of rats. After PM2.5 exposure, excessive reactive oxygen species (ROS) and increased apoptosis of SCs were detected. The expression of the BTB related proteins including ZO-1, Occludin, N-cadherin and β-catenin were significantly decreased and the spatial arrangement of F-actin was completely disordered through Immunofluorescence and Western blots tests. The phosphorylation of Jun N-terminal kinase (JNK), extracellular signal regulatory kinase (ERK), p38 mitogen-activated protein kinase (MAPK) were upregulated and nuclear factor (erythroid-derived 2) -like 2-related factor (Nrf2) was downregulated respectively. However, combined utilization of vitamin C and E were observed to prevent the increase of ROS generation, reduce celluar apoptosis, increase the expression of BTB related proteins, reconstructed the spatial arrangement of F-actin as well as improved the Nrf2 expression and attenuated the phosphorylation of the MAPK kinases and cleaved caspase-3 levels. Furthermore, ERK inhibitor (SCH772984), JNK inhibitor (SP600125) and p38 MAPK inhibitor (SB203580) obviously up-regulated BTB-related proteins expression as well as activated Nrf2 expression at varying degrees, indicating that ROS-MAPKs-Nrf2 is involved in the signaling pathway that leads to PM2.5-induced spermatogenesis dysfunction. These findings indicate that PM2.5 derived from automobile exhaust causes oxidative stress, which in turn causes cellular apoptosis of SCs and damage of the blood-testis barrier, resulting male spermatogenesis dysfunction, in which ROS-MAPK-Nrf-2 pathways may play a key role.