Forsythiaside A attenuates sepsis-induced acute lung injury by suppressing EGR1/GLS2-mediated ferroptosis-associated lipid peroxidation

Sepsis-associated acute lung injury (ALI) is a life-threatening condition with limited targeted therapies. Ferroptosis, an iron-dependent form of regulated cell death, has been implicated in the pathogenesis of ALI. Forsythiaside A (FTA), a natural compound derived from Forsythia suspensa, exhibits anti-inflammatory and antioxidant properties, yet its role in regulating Ferroptosis during sepsis-induced ALI remains unclear. Here, we investigated whether FTA protects against ALI by suppressing the early growth response protein 1/Glutaminase 2 (EGR1/GLS2) axis, a pathway that contributes to Ferroptosis. In a cecal ligation and puncture (CLP)-induced septic mouse model, FTA treatment significantly improved survival, attenuated lung histopathological injury, reduced pulmonary edema, and suppressed inflammatory cytokine levels. RNA Sequencing and gene set enrichment analysis (GSEA) revealed Ferroptosis as a major pathway affected by FTA. Mechanistically, FTA inhibited the upregulation of EGR1 and its downstream target GLS2, leading to decreased glutamate/α-ketoglutarate flux, reduced lipid peroxidation, and enhanced Glutathione Peroxidase 4 (GPX4) activity. In LPS-stimulated MLE-12 lung epithelial cells, FTA similarly suppressed the EGR1/GLS2 axis, mitigated lipid Reactive Oxygen Species (ROS) accumulation, and preserved mitochondrial membrane potential. Overexpression of EGR1 reversed the protective effects of FTA in vitro, while the Ferroptosis inducer Erastin partially abolished FTA-mediated lung protection in vivo. Collectively, our findings suggest that FTA alleviates sepsis-associated ALI, an effect that may involve inhibition of Ferroptosis and suppression of the EGR1/GLS2 axis. FTA thus merits further investigation as a potential therapeutic agent for septic lung injury.