Dimethyl Fumarate attenuates synovial inflammation, reduces nociception, and inhibits the development of post-traumatic osteoarthritis.

There is currently no cure or disease-modifying treatment for post-traumatic osteoarthritis (PTOA). This study aims to assess the efficacy of dimethyl fumarate (DMF), a US-FDA approved drug for multiple sclerosis, as a treatment for PTOA. PTOA was induced in male Lewis rats by medial meniscal transection (MMT) surgery, and DMF was intra-articularly administered once, one week following surgery. PTOA progression was evaluated using histological, molecular, and radiographic analyses, while secondary allodynia was measured longitudinally, and pain-related markers expression were analyzed in dorsal root ganglion (DRG). 3D radiographic imaging by µCT analysis revealed that DMF treatment attenuated cartilage degradation by decreasing cartilage lesions, surface roughness, and osteophyte formation in the proximal tibiae. Histological analysis showed that DMF markedly inhibited cartilage erosion and cartilage surface fibrillation. Gene expression and Luminex analysis indicated that DMF suppressed joint inflammation by inhibiting inflammatory cytokines. DMF mitigated allodynic pain behavior at 6 weeks and repressed pain mediator expression (Calca, Tac1, Trpv1) in lumbar DRGs. Additionally, DMF treatment inhibited inflammatory gene expression and cytokine secretion induced by IL1β stimulation of human articular chondrocytes in vitro. Mechanistically, DMF treatment reduced colony-stimulating factor 2 (CSF2 or GM-CSF) level in the synovial fluid in vivo and inhibited its expression in human OA chondrocytes. Furthermore, siRNA targeting of CSF2 reduced inflammatory gene expression in human chondrocytes. The findings suggest that DMF reduced inflammatory gene expression, inhibited cartilage degeneration, and mitigated PTOA development in rats. It also alleviated pain behavior indicating its potential as a disease-modifying therapy for PTOA.