Kaempferol Inhibits Ferroptosis in Lung Epithelial Cells in LPS-Induced Acute Lung Injury via m5C Methylation of TFRC.

Ferroptosis is involved in the progression of sepsis-induced acute lung injury (ALI). Kaempferol is a flavonoid compound that can protect against ALI. 5-Methylcytosine (m5C) is involved in the pathogenesis of sepsis. This study aimed to investigate the impact of kaempferol on ferroptosis and the underlying mechanism, focusing on m5C methylation. MLE-12 cells were exposed to lipopolysaccharide (LPS) to induce cell injury, and treated with kaempferol to assess ferroptosis by detecting ferrous, glutathione, malonaldehyde, and lipid-reactive oxygen species levels using commercial kits. m5C methylation was assessed using dot blot, RNA immunoprecipitation, dual-luciferase reporter analysis, and RNA stability assay. The results showed that kaempferol inhibited ferroptosis in LPS-induced cells and NOP2/Sun RNA methyltransferase family member 7 (NSUN7)-mediated m5C modification levels. Overexpression of NSUN7 reversed the inhibition of ferroptosis caused by kaempferol. Moreover, NSUN7 knockdown reduced transferrin receptor (TFRC) stability by suppressing its m5C methylation, and TFRC overexpression promoted ferroptosis in cells with NSUN7 downregulation. In conclusion, kaempferol inhibits ferroptosis in lung epithelial cells by suppressing NSUN7-mediated m5C methylation of TFRC. These findings suggest that kaempferol and targeting m5C methylation may be used for the treatment of sepsis-induced ALI.