Tumor Necrosis Factor-alpha (TNF-α), a pleiotropic cytokine primarily produced by activated macrophages, T cells, and other immune cells. TNF-α acts as a master regulator of the inflammatory response. Its signaling, mediated through TNF receptors 1 and 2, drives key pathogenic processes in autoimmune diseases: promoting the release of other inflammatory cytokines (e.g., IL-1, IL-6), enhancing leukocyte migration, activating endothelial cells, and directly inducing tissue damage and apoptosis. In conditions like rheumatoid arthritis, excessive TNF-α production perpetuates synovial inflammation, cartilage destruction, and bone erosion.