TNF and psoriatic arthritis: By binding and inactivating soluble and cell-bound TNF and lymphotoxin α, the binding of TNF-α to TNF-α receptor on cell surface is blocked, and the abnormal immune response and inflammatory process mediated by TNF-α receptor are inhibited.[11] Etanercept was approved by the FDA and EMA in 1998 and 2000, respectively, for the treatment of AS, psoriatic arthritis, rheumatoid arthritis and juvenile idiopathic arthritis.