Dental Follicle Mesenchymal Stem Cell-Derived Exosomes Mitigate Temporomandibular Joint Osteoarthritis in an In Vitro Model via the miR-146a-5p/Traf6/NF-κB Axis

Interleukin-1β-induced inflammation in mandibular condylar chondrocytes (MCCs) plays a key role in temporomandibular joint (TMJ) osteoarthritis (OA), a common degenerative disease lacking effective treatments. Recently, mesenchymal stem cell-derived exosomes have been extensively studied for their therapeutic potential in treating various diseases. In this study, dental follicle stem cells-derived exosomes (DFSC-exo) and rat MCCs were isolated and characterized. Flow cytometry, CCK-8, and would healing assays demonstrated that DFSC-exo treatment significantly reversed the IL-1β-induced increase in apoptosis and restored the proliferation and migration capacities of MCCs. Additionally, RT-qPCR, immunoblotting, and immunofluorescence analyses confirmed that DFSC-exo treatment effectively inhibited the IL-1β-induced downregulation of anabolic markers Sox9, Col2a1, and Aggrecan, as well as the upregulation of inflammation and catabolic indicators Cox2, Mmp9, and Mmp13 in MCCs. Transcriptomic analysis further revealed that DFSC-exo treatment significantly downregulated inflammation-related pathways in MCCs. Both transcriptomic and RT-qPCR analyses showed that DFSC-exo treatment significantly markedly elevated the expression of miRNA-146a-5p, and experiments using its mimic and antagonist demonstrated that mimic enhances, which its inhibition reverses, the protective effects of DFSC-exo on IL-1β-exposed MCCs. A dual-luciferase reporter assay confirmed the direct binding of miRNA-146a-5p to the Traf6 gene. Furthermore, activation of the NF-κB pathway reversed the protective effects of both DFSC-exo and miRNA-146a-5p mimic on IL-1β-exposed MCCs. Collectively, these findings suggest that miRNA-146a-5p from DFSC-exo binds to the Traf6 gene, suppresses the downstream NF-κB signaling pathway, and mediates the protective effects on IL-1β-exposed MCCs, highlighting the therapeutic potential of targeting the miRNA-146a-5p/Traf6/NF-κB axis for the treatment of TMJ OA.