Psoriatic arthritis under the influence of IFNγ.

Psoriasis is a common multifactorial autoimmune disease of the skin, and in a large percentage of patients, immune responses involve nail and joint pathology, which develop psoriatic arthritis (PsA). Historically, T helper 1 (Th1)-derived-IFN-γ was abundantly detected in psoriatic skin and its correlation with development and severity of PsO, led to an early classification of psoriasis as a Th1-mediated disease. Investigations of the cellular and molecular mechanisms of PsO pathogenesis in recent years, together with impressive results of biologics against interleukin 17A (IL-17) have shifted focus on IL-17A. However, the contributions of IFN-γ in IL-17 induced pathology and its involvement in the development of PsA have been largely overshadowed. This review summarizes the current knowledge on IFN-γ and provides new insights on the contribution of IFN-γ to PsO and PsA disease pathogenesis and development.