CD4 and rheumatoid arthritis: DJ-1 has been shown to inhibit the differentiation of pathological Th cell subsets (Th17, RANKL+CD4 + T cells) and the production of pro-inflammatory cytokines IL-17A and TNF-α, induce the differentiation of Tregs, weaken the expression levels of OC-related factors TRAP, ATP6v0d2, NFATc1, and CTSK, inhibit the production of OCs induced by RANKL and IL-17A, and regulate the balance of Th17/Treg, thereby playing an important therapeutic potential in the pathogenesis of RA (226).