Integration of scRNA-seq and bulk RNA-seq reveals that macrophage ferroptosis inhibits MSC osteogenic differentiation in inflammatory microenvironments

BACKGROUND: Bone infections disrupt bone homeostasis and impair regeneration. Ferroptosis is closely associated with bone homeostasis regulation. However, the molecular mechanisms of these effects remain unclear. The present study sought to investigate the impacts of macrophage ferroptosis on osteogenic regeneration under an inflammatory microenvironment. METHODS: Single-cell and bulk RNA sequencing were used to assess cellular heterogeneity and ferroptosis gene expression during bone infection. In vivo, in vitro, and clinical sample analyses were performed to assess the impact of macrophage ferroptosis on PANoptosis and mesenchymal stem cell (MSC) osteogenic differentiation in the inflammatory microenvironment. RESULTS: During bone infection, macrophages exhibit lipid peroxidation, reactive oxygen species accumulation, upregulated acyl-CoA synthetase long-chain family member 4 (Acsl4) and lysophosphatidylcholine acyltransferase 3 (Lpcat3), and downregulated glutathione peroxidase 4 (Gpx4) and macrophage migration inhibitory factor (Mif). Additionally, macrophage ferroptosis promoted M1 macrophage polarization, increased MSC PANoptosis, and inhibited bone regeneration in the inflammatory microenvironment. CONCLUSION: Inhibiting macrophage ferroptosis promoted the polarization of macrophages towards the M2 phenotype, alleviated MSC PANoptosis, and promoted bone regeneration in the inflammatory microenvironment. This study provides a novel perspective on the pathological mechanisms of bone infections and identifies potential therapeutic targets.