IL17A and rheumatoid arthritis: The expression of cytokines (IL-1, IL-6, IL-8, IL-15, IL-17, IL-33, TNF-α, IFN-γ), thrombospondin-1, chemokines (CXCL12, CXCL8, CCL20), etc. can be increased, leading to the aggregation of inflammatory cells, further exacerbating the synovial inflammation and other pathological reactions of RA.