TGFB1 and rheumatoid arthritis: Moreover, even through some cytokines, especially IL-6, IL-23, and transforming growth factor β (TGF-β), which facilitate the differentiation of Th17 [32], are demonstrated in the RA synovium; the other cytokines, such as IFN-γ, which counteract their differentiation, are also found [1,2].