These results again show that IL-23 mediates its effects further upstream compared to IL-17A and that blocking IL-17A could lead to a more targeted MS therapy than blocking IL-23, which failed in a phase II clinical trial to treat patients with relapsing remitting MS (Havrdová et al., 2016; Segal et al., 2008). Here, IL17A is linked to relapsing-remitting multiple sclerosis.