IL33 and rheumatoid arthritis: In addition to functioning as a proinflammatory cytokine in the pathogenesis of asthma, atopic dermatitis, and allergic shock, the diseases characterized by Th2 inflammatory responses (26, 27, 31, 32), IL-33 was also found to be essential for the initiation of Rheumatoid arthritis, which is an autoimmune disease characterized by Th1/Th17 responses (33, 34).