Expanding the Psoriasis Framework: Immunopathogenesis and Treatment Updates

Psoriasis is a chronic heterogeneous condition with multiple available treatment options that have resulted in dramatic disease improvements for patients. IL-23/IL-17 signaling is the central immune signaling pathway driving psoriasis, though recent research has uncovered other key contributing signals such as IL-17C, IL-17F, IL-36, and tyrosine kinase 2 (TYK2). Novel therapeutic targets inhibiting these cytokines have expanded our understanding of the pathogenesis of psoriasis. IL-23/IL-17 signaling is critical for the development of epidermal hyperplasia and the mature psoriatic plaque in susceptible individuals. Increased IL-17 and IL-23 expression works synergistically with other cytokines, such as IL-12, IL-22, IL-36, tumor necrosis factor (TNF), and interferon (IFN), to help create a self-sustaining, feed-forward circuit in keratinocytes, which contributes to the chronicity of the disease. This clinical review highlights recent discoveries in the immunopathogenesis of psoriasis and summarizes new antipsoriasis therapies targeting IL-36, IL-17F, aryl hydrocarbon receptors (AHRs), phosphodiesterase 4 (PDE4), and TYK2 signaling. Despite recent success in the treatment of psoriasis, continued research is needed to further advance disease understanding and shape management strategies.