IL20 and rheumatoid arthritis: Numerous pro-inflammatory cytokines including, interleukin-1β (IL-1β), IL-2, IL-3, IL-6, IL-7, IL-8, IL-12/23, IL-17, IL-18, IL-19/IL-20, IL-32, IL-35, tumor necrosis factor-α (TNF-α), interferon-α/γ (IFNα/γ) and oncostatin M (OSM) are prominently elevated in rheumatoid arthritis (RA) where they are involved in immune-mediated inflammation characteristic of this autoimmune disease [1,2,3,4,5].