Targeting IL-17 in psoriasis: from cutaneous immunobiology to clinical application.

Psoriasis vulgaris is a chronic, immune-mediated inflammatory skin disease associated with complex genetic susceptibility. Although the hallmark of psoriasis is characterized by cutaneous inflammation and keratinocyte hyperproliferation, recent studies show that the pathologic features observed in psoriasis arises as a result of innate and adaptive immune activation in genetically prone individuals. Studies focused on the microenvironment in the skin of psoriasis lesions have revealed novel cellular and cytokine abnormalities of the immune system. One pathway important is the role of the TH17/IL-17 dysregulation. The recent development of biologics that target the IL-17 cytokine pathway has confirmed the importance of TH17 and IL-17 homeostasis in the skin and yielded potent therapies in the treatment of psoriasis, and potentially other autoimmune diseases.