IL17A and psoriasis: The increased production of pro-inflammatory mediators and chemokines such as IL-1, IL-6, IL-23, IL-17, and TNF-α plays a crucial role in the pathogenesis of psoriasis (Croxford et al., 2014; Grine et al., 2015; Harden et al., 2015; Kim and Krueger, 2015).