TNF and psoriatic arthritis: Accordingly, since excess levels of TNF-α are a distinctive feature of many inflammatory disorders, several anti-TNF-α antagonists have been developed and shown to be effective in a variety of autoimmune inflammatory diseases, including rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, plaque psoriasis, juvenile idiopathic arthritis, ulcerative colitis, and Crohn’s disease [5,6].