TNF and rheumatoid arthritis: The proinflammatory cytokines, such as tumor necrosis factor α (TNFα), IL-1β, and IL-6, are produced by activated macrophages and stimulate the synovial fibroblasts (SFs), also called fibroblast-like synoviocytes (FLS), that play a critical role in the joint destruction that occurs in RA [19].