IL17A and rheumatoid arthritis: The present study demonstrates that 1,25(OH)2D3 reduces the production of RANKL and the secretion of TNF-α, IL-17, and IL-6 in PBMCs of RA patients, which indicates that 1,25(OH)2D3 might be able to decrease damage of cartilage and bone in RA patients by regulating the balance between proinflammatory and anti-inflammatory cytokines.