IL17A and psoriasis: In this condition, T-helper cells (Th1, Th17, Th22) after their activation and proliferation produce a number of pathogenic cytokines: tumour necrosis factor-α (TNF-α), interferon (IFN)-γ, and interleukin (IL)-2, IL-6, IL-17A, IL-17F, IL-22, IL-26 [59,60], which is backed by a well-documented strong relationship between obesity and psoriasis.