Update on the etiopathogenesis of psoriasis (Review).

Psoriasis is one of the most common immune-mediated chronic inflammatory skin disorders, involving hyperproliferative keratinocytes and infiltration of T cells, dendritic cells, macrophages, and neutrophils. Multiple factors appear to play important roles in the pathogenesis of psoriasis. These environmental (e.g., infectious agents and trauma), genetic, and immunologic factors are reviewed in this article. Although the pathogenesis of psoriasis remains to be established, data suggesting immune cell dysregulation in the skin are available. The involvement of the immune system, particularly T cells, in the etiopathogenesis of psoriasis is discussed in this review, indicating a potential justification for innovative treatment intervention. Besides describing pathogenic T cells, the aim of the review was to assess the function of newly identified antimicrobial peptides (AMPs), interleukin (IL)-23, IL-17, and tissue resident memory cells (TRMs), and their role in psoriasis. Furthermore, new insights were presented regarding TRMs, a recently identified subset of memory T cells, and the role they play in the local memory of disease, making them a potential new therapeutic target in psoriasis. Finally, current developments in T-cell research and cytokine-targeted therapy for psoriasis treatment are reviewed.