IL17A and autoimmune disease: Th17 cells and IL-17 are involved in host defenses by way of immunothrombosis, and promote the removal of pathogenic microorganisms (Amezcua Vesely et al., 2019; Kitamoto et al., 2020), but too much IL-17A is fatal for the host, and can lead to a variety of inflammatory or autoimmune diseases (Gravallese and Schett, 2018; Jo et al., 2018).