Therapeutic Effects of WIN55,212-2 on Temporomandibular Joint Osteoarthritis: Integration of In Vivo Cartilage Protection and In Vitro Anti-inflammatory Mechanisms

Objective: This study explores the therapeutic potential of the synthetic cannabinoid WIN55,212-2 (WIN55) in temporomandibular joint osteoarthritis (TMJOA) and deciphers its molecular mechanisms.Methods: TMJOA was modeled in 8-week-old male Wistar rats via monosodium iodoacetate (MIA) injections, with subsequent WIN55 administration. Histological assays, Safranin-O staining, and micro-CT analysis were employed to assess cartilage damage and subchondral bone alterations. Primary condylar chondrocytes from 3-week-old rats were cultured and exposed to IL-1b and WIN55 treatments. Inflammatory mediators and matrix component expression were analyzed using ELISA, cytokine arrays, Western blotting, qPCR, and RNA sequencing.Results: WIN55 markedly mitigated cartilage degradation in MIA-induced TMJOA, reflected in enhanced Mankin scores, retained proteoglycan content, and preserved subchondral bone structure. In vitro, WIN55 suppressed IL-1b-driven upregulation of pro-inflammatory cytokines (IL-6, TNF-a) and chemokines (CCL2, CCL5, CCL20, CXCL1, CXCL2, CXCL3) in condylar chondrocytes. Transcriptomic profiling identified that WIN55 reversed four key pathways altered by IL-1b: ECM-receptor interaction, TNF signaling, IL-17 signaling, and cytokine-cytokine receptor interaction. Crucially, WIN55 downregulated IL-1b-induced CSF-1, CSF-2, and CSF-3 expression, alongside alterations in lncRNA and circRNA profiles.Conclusion: WIN55 exhibits therapeutic promise for TMJOA by preventing cartilage degradation in vivo and modulating inflammatory cascades in vitro. These results lay the groundwork for advancing cannabinoid-based therapies in TMJOA management.