N6 methyladenosine eraser FTO suppresses Staphylococcus aureus‐induced ferroptosis of bone marrow mesenchymal stem cells to ameliorate osteomyelitis through regulating the MDM2/TLR4/SLC7A11 signaling pathway

Abstract Osteomyelitis is a bone destructive inflammatory disease caused by infection. Ferroptosis is closely related to multiple inflammatory diseases, but the role of ferroptosis in Staphylococcus aureus (SA)‐induced osteomyelitis remains unknown. In the present study, we found that SA treatment promoted the accumulation of iron, Fe 2+ , lipid peroxide, and malondialdehyde, increased TFRC and reduced FTH1 and GPX4 to trigger ferroptosis in rat bone marrow mesenchymal stem cells (BMSCs). Interestingly, increased level of N6 methyl adenosine (m6A) modification along with decreased expression level of m6A eraser FTO were observed in SA‐induced BMSCs, while upregulating FTO alleviated SA‐triggered ferroptosis and protected cell viability in BMSCs. Mechanistically, MDM2 was identified as a target of FTO‐mediated m6A demethylation, and FTO upregulation promoted MDM2 instability to downregulated TLR4 signal and elevate the expression of SLC7A11 and GPX4 in SA‐induced BMSCs. Functional recovery experiments verified that overexpressing MDM2 or TLR4 reversed the inhibiting effect of FTO upregulation on ferroptosis in SA‐treated BMSCs. Additionally, FTO upregulation restrained ferroptosis and pathological damage to bone tissue in SA‐induced osteomyelitis model rats. Altogether, m6A eraser FTO alleviates SA‐induced ferroptosis in osteomyelitis models partly through inhibiting the MDM2‐TLR4 axis.