TNF and rheumatoid arthritis: Monocytes and macrophages are major inflammatory cells that synthesize and secrete proinflammatory cytokines [e.g. tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6] (Brennan and McInnes 2008; Siouti and Andreakos 2019), which are major drivers of RA pathogenesis.