AAV-mediated Overexpression of IL-10 Mitigates the Inflammatory Cascade in Stimulated Equine Chondrocyte Pellets

Background: Following joint trauma, a posttraumatic inflammatory cascade drives degeneration of the joint. We aimed to assess whether transduction of chondrocytes with AAV5 overexpressing the immunomodulatory cytokine IL-10 would have protective effects in pellet cultures stimulated with IL-1β. Methods: Chondrocytes were isolated from 3 healthy horses and were transduced with AAV5-IL-10 at a dose of 1 x 105vg/cell. Chondrocyte pellets were formed by centrifugation and were stimulated with IL-1β starting 48 hours following transduction. After 2, 6 and 14 days in culture, supernatants were collected for cytokine analysis and RNA was isolated from cells for gene expression analysis. Pellets were also collected for biochemical analysis. Results: Transduction of chondrocytes led to significant increases in IL-10 expression. IL-10 expression was further enhanced by IL-1β stimulation. IL-10 overexpression led to significantly decreased expression of IL-1β and ADAMTS4. PGE2 synthesis was also significantly decreased. IL-1β mediated suppression of GAG synthesis was not rescued by IL-10. Conclusions: Overexpression of IL-10 modulates the inflammatory response in chondrocytes, which may mitigate some of the deleterious effects of pro-inflammatory cascades in the posttraumatic joint. AAV5-IL-10 led to efficient and sustained overexpression of IL-10 in chondrocytes and could represent a viable treatment option for preventing osteoarthritis.