Inhibitors of IL-17 or the IL-17 signaling pathway, including Secukinumab (AIN457), Ixekizumab (LY2439821), and Brodalumab (AMG827), have been approved in recent years for clinical use for the treatment of ankylosing spondylitis [100,101], moderate-to-severe plaque psoriasis and psoriatic arthritis [102,103,104], radiographic and nonradiographic spondyloarthritis [105], and Netherton’s syndrome [106] (Table 2), and have shown excellent efficacy, safety, and tolerability. Here, IL17A is linked to psoriatic arthritis.