MAVS signaling exacerbates chondrocytes extracellular matrix degradation in osteoarthritis.

Osteoarthritis (OA) is a prevalent age-related joint disorder with limited treatment options. Chronic activation of the innate immune response in chondrocytes plays a key role in OA progression. However, the underlying mechanisms remain incompletely understood. Here, we report that mitochondrial antiviral signaling protein (MAVS) exacerbates cartilage extracellular matrix (ECM) degradation in OA. MAVS activation is observed in chondrocytes from both OA patients and the destabilization of the medial meniscus (DMM) mouse model. Both constitutive and chondrocyte-specific MAVS knockout alleviate cartilage degradation, osteophyte formation, subchondral bone remodeling, and synovitis in DMM mice. Conversely, MAVS overexpression aggravates these OA phenotypes. Mechanistically, cytosolic accumulation of mitochondrial double-stranded RNA in chondrocytes triggers MAVS activation, leading to MAVS-nuclear factor κB-dependent ECM degradation by inducing matrix metalloproteinase 3 (MMP3) and MMP13. Pharmacologically blocking MAVS using L-lactate significantly attenuates ECM degradation and OA progression. These findings suggest that MAVS signaling is critical in OA pathogenesis and may be a potential therapeutic target for OA treatment.