During the pathogenesis of osteoarthritis (OA), chondrocytes produce extracellular matrix-degrading proteins such as matrix metalloproteinases (MMPs) as well as pro-inflammatory cytokines such as interleukin (IL)-1 and tumor necrosis factor (TNF) leading to the loss of chondrocyte cellularity and cartilage degeneration2–6. Here, TNF is linked to osteoarthritis.