MiR-370-3p regulate TLR4/SLC7A11/GPX4 to alleviate the progression of glucocorticoids-induced osteonecrosis of the femoral head by promoting osteogenesis and suppressing ferroptosis.

OBJECTIVES: Osteonecrosis of the femoral head (ONFH) represents a severe complication of glucocorticoids (GCs) therapy in clinical settings. MicroRNAs (miRNAs) are critically involved in the progression of GCs-induced ONFH, with ferroptosis playing a central role in its pathology. However, the regulatory effects of specific miRNAs targeting ferroptosis in ONFH have not been previously explored. The aim of this study was to elucidate the effect and the specific molecular mechanisms of miR-370-3p in the progression of GCs-induced ONFH. METHODS: In this study, we first established a rat model of GCs-induced ONFH and analyzed changes in osteogenesis and ferroptosis. Subsequently, we performed miRNA sequencing on bone marrow-derived mesenchymal stem cells (BMSCs) after dexamethasone treatment. In vitro, we assessed the effects of miR-370-3p on cell proliferation, osteogenic activities, and ferroptosis in BMSCs. We used dual luciferase assays to identify the target gene of miR-370-3p, examining its regulatory effects on osteogenesis and ferroptosis. In vivo, we estimated the effect of miR-370-3p on the femoral head by isolating exosomes from BMSCs overexpressing miR-370-3p and administering them to rats. RESULTS: We observed that impaired osteogenesis and enhanced ferroptosis are principal pathogenic factors in the progression of GCs-induced ONFH. We identified miR-370-3p as a significant regulatory element in bone marrow-derived mesenchymal stem cells (BMSCs) through miRNA sequencing following GCs treatment. Moreover, miR-370-3p could protect BMSCs viability against GCs impairment in vitro and enhance Ki67 expression in the femoral head. The osteogenic capacity of BMSCs was strengthened by miR-370-3p under GCs condition. In addition, miR-370-3p was found to reduce ferroptosis activities, including iron overload and lipid peroxidation. Mechanically, we found that toll-like receptor 4 (TLR4) was the target of miR-370-3p. And miR-370-3p could exert critical regulatory effects by targeting TLR4/solute carrier family 7 member 11 (SLC7A11)/glutathione peroxidase 4 (GPX4) axis under GCs intervention. Importantly, inhibition of ferroptosis partially restored osteogenic capacity of BMSCs in vitro. In a rat model of GCs-induced ONFH, miR-370-3p played a critical protective role in the femoral head by enhancing osteogenesis and inhibiting ferroptosis. CONCLUSION: miR-370-3p could regulate the changes in osteogenesis and ferroptosis in the progression of GCs-induced ONFH through targeting TLR4/SLC7A11/GPX4 axis. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: This study is the first to unveil the regulatory interaction between miRNA and ferroptosis in GC-induced ONFH, providing valuable insights into its pathogenesis and identifying potential therapeutic targets.