TNF and Arthritis: Tumor necrosis factor alpha (TNF-α) is a cytokine that has an important proinflammatory role in arthritis where together with other pro-inflammatory cytokines, TNF-α mediates the inflammatory response of joint chondrocytes, synovial fibroblasts, and osteoclasts that secrete tissue-damaging enzymes such as the matrix metalloproteinases [14].