IL37 and rheumatoid arthritis: Recent studies have indicated that IL-37 downregulated the expression of proinflammatory cytokines in chronic inflammatory diseases such as systemic lupus erythematosus (SLE) [24], rheumatoid arthritis (RA) [25–27], and ankylosing spondylitis (AS) [28], suggesting that IL-37 might abrogate proinflammatory cytokine production to reduce inflammatory responses in AOSD.