The precise etiology of RA is not known, but it is evident that proinflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6), and transforming growth factor-β (TGF-β) play an important role in pathogenesis of disease [10]. Here, TNF is linked to rheumatoid arthritis.