IL17A and hidradenitis suppurativa: Interestingly, in acne and hidradenitis suppurativa, mice experiments have shown the specific contribution of C. acnes in the development of dual IL-17+IFN-γ+ CD4+ cells, although in these disorders the subsequent transdifferentiation into IL-17-IFN-γ + exTh17 cells seems less pronounced (44, 46).