IL2 and rheumatoid arthritis: Shi et al. in situ injected a nanoparticle drug delivery system loading IL-2, TGF-β, and cyclin dependent kinase inhibitor to induce Treg differentiation and decrease Th17 production in RA model, thus reducing the secretion of TNF-α in the knee, which facilitated to relieve the severity and progression of arthritis [50].