TNF and rheumatoid arthritis: Moreover, IL-12, IL-18, and IFN-γ, the drivers of Th1 differentiation have been also identified in synovial tissues of RA patients (100, 101), although the levels of Th1-mediated IFN-γ were relatively low compared with those of TNF-α, IL-1, or IL-6 derived from synovial fibroblasts (102, 103).