IL17A and psoriasis: At present, the treatment of psoriasis has come to a new stage, and a large number of biological agents are applied in clinical practice, such as tumor necrosis factor-α inhibitors (TNF-αi, such as adalimumab, infliximab, etc.), IL-17 inhibitors (IL-17i, such as secukinumab, ixekizumab, etc.), IL-23 inhibitors (IL-23i, ustekinumab, guselkumab, etc.)(5).