IL21 and rheumatoid arthritis: RA-FLS releases important inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-21, IL-22, and IL-32), chemokines (CXCL1, CXCL5, MCP-1, G-CSF, and IL-8) and Inflammatory mediators (TLR-2, TLR-3, TLR-4, iNOS, and COX-2), which promotes the infiltration of monocytes, macrophages, neutrophils, DCs, T cells, and B cells into joints and results in chronic inflammation and joint destruction (Bottini and Firestein, 2013; Ganesan and Rasool, 2017).