TNF blockers are already in clinical use (infliximab, etanercept, certolizumab and golimumab), attempting to prevent the signaling action of TNF, thereby down-regulating the expression levels of IL-22 in many inflammatory diseases, such as Crohn’s disease, rheumatoid arthritis, ulcerative colitis, psoriatic arthritis, ankylosing spondylitis and juvenile idiopathic arthritis. This evidence concerns the gene TNF and psoriatic arthritis.