CD4 and rheumatoid arthritis: In our studies, we confirmed that compared with HC, RA CD4+T cells displayed more obvious cellular senescence features, characterised by elevated SA-β-Gal activity (CD4+Ki67−T cells), increased gene expression of senescence-associated cyclin-dependent kinase inhibitors (P53, P21, and P16), and enhanced secretion of SASP factors (Fig. S1A–1D).