IL17A and rheumatoid arthritis: Additionally, T helper type 1 (Th1) and Th17 cells secrete proinflammatory cytokines, including IL-17 and interferon-gamma (IFN-γ), promoting inflammatory responses and contributing to various autoimmune diseases, such as multiple sclerosis, collagen-induced arthritis, and rheumatoid arthritis (RA) [30].