IL21 and rheumatoid arthritis: In CIA rats, quercetin administration has been shown to decrease the contents of Th17-related cytokines IL-17A, IL-21, and ROR-γt and inflammatory mediators TNF-α, IL-1β, IL-6, PGE2, and COX-2 which play a key role in the development of RA, decreased the protein expression levels of inflammatory corpuscles NLRP3, Caspase-1, and IL-1β, and increased the expression of Treg-related cytokines IL-10, TGF-β, and Foxp3.