IL33 and rheumatoid arthritis: In the early stage, it plays a pro-inflammatory role by promoting the migration of inflammatory cells and the release of related factors, while in the regression phase of RA, IL-33 affects the proliferation and differentiation of ILC2 and TH2 cells, as well as the tendency to regulatory M2 phenotypic production, especially the activation of Treg cell population, which are very beneficial for reversing RA (53).