Abstract
Background: Psoriasis is a chronic skin condition traditionally believed to involve the Th1 pathway. Recently, the IL-23/Th17/IL-17 pathway has been highlighted in the pathogenesis of psoriasis and other autoimmune inflammatory conditions. From a clinician’s perspective, we sought to review the basic science data relevant to IL-17’s role in psoriasis pathogenesis.
Methods: We performed a Pubmed and Web of Knowledge search for English articles starting from 1990 that discussed the Th17 pathway. Search terms such as “IL-17” and “psoriasis” were utilized.
Results: The IL-17 pathway is regulated by IL-23, a cytokine that is vital for the expansion and maintenance of the Th17 cell population. Th17 derived cytokines (IL-17A, IL-17F, IL-17A/F and IL-22) were elevated in both psoriasis-like murine models and human psoriatic lesional biopsies. Ixekizumab (anti-IL-17A) treatment of psoriasis was found to normalize levels of IL-17 downstream gene products.
Conclusion: Both preclinical and clinical studies support the central role of IL-17 in the pathogenesis of psoriasis.
Declaration of interest
Dr John Koo is a speaker for AbbVie and Leo. Dr Koo conducts research for Amgen, Janssen, Novartis, Photomedex, Galderma, Pfizer, and Merck. Dr Koo has no stocks, employment or board memberships with any pharmaceutical company. None of the grants were directly related to this article. The other authors (Mona Malakouti, Gabrielle Brown, Eva Wang and Ethan Levin) report no conflicts of interest.