STAT1 and Arthritis: JAK inhibitors disrupt γc-chain cytokine signalling in CD4+ Th cells and block IL-6 signalling, which rapidly suppresses collagen-induced arthritis, the expression of inflammatory cytokines, and STAT1-dependent gene expression and interferes with the differentiation of Th1 and Th2 cells and the generation of inflammatory cytokines, such as IL-1β, IL-6 and IL-23, by Th17 cells [28].