FDX1 regulates leydig cell ferroptosis mediates PM2.5-induced testicular dysfunction of mice

Epidemiological studies have established an association between chronic exposure to PM2.5 and male infertility. However, the underlying mechanisms were not fully revealed. In this study, we established mice models exposed to PM2.5 for 16 weeks, and a significant decrease in sperm quality accompanied by an increase in testosterone levels were observed after PM2.5 exposure. Moreover, treatment with ferrostatin-1 (Fer-1), a specific ferroptosis inhibitor, effectively mitigated PM2.5-induced testicular dysfunction in mice. And lipid peroxidation and ferritin accumulation were found to be significantly increased in Leydig cells of testes with a PM2.5-dose dependent manner. Further investigations revealed that TM-3 cells, a mouse Leydig cell line, were prone to ferroptosis after PM2.5 exposure, and the cell viability was partly rescued after the intervention of Fer-1. Furthermore, our results supported that the ferroptosis of TM-3 cells was attributed to the upregulation of ferredoxin 1 (FDX1), which was the protein transferring electrons to cytochrome P450 family 11 subfamily A member 1 to aid lysing cholesterol to pregnenolone at initial of steroidogenesis. Mechanically, PM2.5-induced FDX1 upregulation resulted in cellular ROS elevation and ferrous iron overload, which together initiated an autoxidation process of polyunsaturated fatty acids in the cell membrane of Leydig cells until the accumulated lipid peroxides triggered ferroptotic cell death. Simultaneously, upregulation of FDX1 promoted steroidogenesis and let to an increased level of testosterone. In summary, our work suggested that FDX1, a mediator involving steroidogenesis, was a key regulator in PM2.5-induced Leydig cells ferroptosis.

Automated summary

Epidemiological studies have revealed an association between chronic exposure to PM2.5 and male infertility, but the underlying mechanisms were unclear. In this study, mice models exposed to PM2.5 showed decreased sperm quality and increased testosterone levels. Ferrostatin-1 treatment effectively mitigated PM2.5-induced testicular dysfunction. Further investigations showed that PM2.5 exposure led to ferroptosis in Leydig cells, which was partially rescued by Fer-1 intervention. The upregulation of FDX1, a mediator involved in steroidogenesis, caused cellular ROS elevation and ferrous iron overload, leading to ferroptotic cell death and increased testosterone levels.