TNF and rheumatoid arthritis: Activated macrophages are one of the main producers of potent pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α) [3], interleukin-1β (IL-1β) [4], interleukin-8 (IL-8) [5] and monocyte chemoattractant protein-1 [6], which perpetuate both the innate and adaptive immune response.[4] Macrophage production of these pro-inflammatory factors amplifies osteoclast function, resulting in increased bone resorption and loss during RA [7, 8].