M2-polarized RAW 264.7 macrophage-derived exosomal miR-383-5p alleviates chronic periodontitis by targeting ACSL4 to regulate osteogenic and osteoclastogenic differentiation

Chronic periodontitis (CP) is characterized by inflammatory alveolar bone destruction. M2 macrophage-derived exosomes (M2-exosomes) may restore bone homeostasis, but the contribution of ACSL4-associated ferroptosis and lipid-peroxidation signaling remains insufficiently defined. This study investigated the function and mechanism of M2-exosomal miR-383-5p in CP. Exosomes from M2-polarized RAW 264.7 macrophages were isolated and characterized by TEM, NTA, positive markers (CD63 and TSG101), and negative markers (Calnexin and GM130). Osteogenic differentiation of periodontal ligament stem cells (PLSCs) and RANKL-induced osteoclastogenesis were assessed by staining, RT-qPCR, and Western blot. miRNA array profiling, bioinformatics, dual-luciferase reporter and RNA pull-down assays identified miR-383-5p/ACSL4 targeting. ACSL4 overexpression rescue, miR-383-5p-depleted exosomes, and ferroptosis-related readouts (ROS, Fe 2 ⁺, GSH, MDA, TFRC, GPX4, SLC7A11, and ACSL4) were used for mechanistic validation. A ligature-induced mouse model was evaluated by quantitative Micro-CT and histology. Serum and gingival-tissue miR-383-5p and ACSL4 were assessed in clinical samples. M2-exosomes promoted osteogenesis and inhibited osteoclastogenesis. miR-383-5p was enriched in M2-exosomes; its inhibition weakened these effects, whereas ACSL4 silencing rescued the impairment. ACSL4 overexpression reversed M2-exosome-mediated protection and partly restored ferroptosis-related alterations, including increased ROS, Fe 2 ⁺ and MDA, decreased GSH, increased TFRC/ACSL4, and decreased GPX4/SLC7A11. miR-383-5p-depleted exosomes showed attenuated regulatory effects. In vivo, M2-exosomes reduced CEJ-ABC distance, improved BV/TV and Tb.Th, and decreased inflammation and collagen loss. In patients, serum and gingival miR-383-5p were downregulated, gingival ACSL4 was upregulated, and serum miR-383-5p showed high specificity but modest sensitivity for CP. M2-exosomes alleviate CP by delivering miR-383-5p, which targets ACSL4 and modulates ferroptosis-related lipid-peroxidation signaling to enhance osteogenesis and suppress osteoclastogenesis. Serum miR-383-5p is a promising adjunctive, rather than standalone, biomarker for CP.