New insights of T cells in the pathogenesis of psoriasis.

Psoriasis is one of the most common immune-mediated chronic, inflammatory skin diseases characterized by hyperproliferative keratinocytes and infiltration of T cells, dendritic cells, macrophages and neutrophils. Although the pathogenesis of psoriasis is not fully understood, there is ample evidence suggesting that the dysregulation of immune cells in the skin, particularly T cells, plays a critical role in psoriasis development. In this review, we mainly focus on the pathogenic T cells and discuss how these T cells are activated and involved in the disease pathogenesis. Newly identified 'professional' IL-17-producing dermal γδ T cells and their potential role in psoriasis will also be included. Finally, we will briefly summarize the recent progress on the T cell and its related cytokine-targeted therapy for psoriasis treatment.