TNF and rheumatoid arthritis: Arbitrarily, the chronic synovial inflammation in RA can be defined as an imbalance between proinflammatory and anti-inflammatory cytokines with preponderance in proinflammatory ones including interleukins (ILs) IL-1β, IL-6, IL-8, IL-17, and tumor necrosis factor (TNF) TNF-α [1].