Gut microbiota-derived glutathione from metformin treatment alleviates intestinal ferroptosis induced by ischemia/reperfusion.

BACKGROUND: Intestinal ischemia/reperfusion injury (IIRI) is a life-threatening condition caused by multiple organ and system failures induced by dysbiosis and gut leakage. Metformin has demonstrated efficacy in protecting against IIRI, although the precise role of the gut microbiota in the underlying mechanism is still ambiguous. METHODS: This study examined intestinal barrier function and ferroptosis-related parameters in mice with IIRI following treatment with metformin. Additionally, dirty cages and antibiotics were utilized to investigate the impact of the microbiota on the effects of metformin. The analysis included an assessment of the microbial composition of metformin-treated mice and the biosynthetic activity of specific metabolites. RESULTS: Metformin effectively reduced gut leakage induced by IIRI, as evidenced by decreased intestinal permeability and increased Occludin, ZO-1, Claudin-1, and MUC-1 expression. A decrease in the expression of the pro-ferroptotic proteins ACSL4, TFR1, and VDAC2/3 and a decrease in dihydroethidium (DHE) fluorescence, iron, malondialdehyde (MDA), and myeloperoxidase (MPO) were further observed in metformin-treated mice. In contrast, the damage to the GPX4/GSH system caused by IIRI was reversed after metformin treatment, as shown by increases in GPX4, SLC7A11, and GSH. The antiferroptotic effects of metformin were phenocopied by its fecal microbiota but were eliminated by antibiotic intake. 16S rRNA analysis revealed that the metformin-modulated gut microbiota was characterized by increased Lactobacillus murinus, which expressed higher levels of GshF that contributed to the mitigation of IIRI. CONCLUSIONS: Murine gut microbiota mediated the anti-ferroptotic effect of metformin on IIRI, and the resulting increase in microbial GSH synthesis could serve as a critical pathway for anti-IIRI.