IL17A and psoriasis: Interleukin-17A (IL-17A), originally known as the cytotoxic T lymphocyte-associated antigen 8 (CTLA-8), is a pro-inflammatory cytokine (Rouvier et al., 1993), and has emerged as a new therapeutic target in chronic inflammatory diseases, such as psoriasis (Karbach et al., 2014) and vitiligo (Zhou et al., 2018).