CD4 and rheumatoid arthritis: ITK kinase levels are significantly increased in CD4 + T cells of patients with RA, animal experiments, it was further revealed that an ITK inhibitor downregulated Th17 cells and effectively upregulated Treg cells by regulating Foxo1 translocation, which significantly inhibited the transformation of Treg cells into Th17 cells and restored the balance of Th17/Treg cells by downregulating the PI3K-Akt-mTOR signalling pathway, indicating that blocking ITK may be an effective strategy to treat RA (225).