TRAPPC9 Modulation Regulates IL-1β-Induced Chondrocyte Inflammation

Osteoarthritis (OA) is a debilitating degenerative joint disease that results in chronic pain and inflammation due to progressive mechanical and proteolytic cartilage degradation. Articular chondrocytes, the main cell type present in cartilage, are responsible for the deposition and maintenance of the cartilage extracellular matrix (ECM). However, following damage and inflammation, chondrocytes undergo hypertrophy, apoptosis, and contribute to inflammation and ECM degradation. NF-κB signaling is known to be dysregulated in OA. TRAPPC9, a vesicle trafficking protein, is known to directly activate NF-κB signaling in neuronal and bone cells, however, the biological significance of this protein in chondrocytes has yet to be elucidated. Here, we demonstrate that TRAPPC9 enhances pro-inflammatory gene and protein expression in murine primary articular chondrocytes. Furthermore, we show that TRAPPC9 elicits these responses via phosphorylation of P-100 that activates non-canonical NF-κB signaling. Taken together, these findings suggest TRAPPC9 may be a potential therapeutic target to decrease inflammation and matrix degradation during OA pathology.