The role of the IL-23/IL-17 pathway as a key driver of skin inflammation is supported by the clinical efficacy of agents that block IL-23 or effector cytokines regulated by IL-23 (eg, IL-17A alone or in combination with IL-17F) in the treatment of plaque psoriasis (Blauvelt et al, 2017a, 2017b; Langley et al, 2014; Reich et al, 2019; Sawyer et al, 2019). Here, IL17A is linked to psoriasis vulgaris.