Distinct Th17 cell populations with opposite functions have also been described in human,15,16 with a clear pathogenic role in several autoimmune diseases including CD.17,18 Enrichment of IFNγ/IL-17 co-producing Th17 cells with a pathogenic profile has been reported in the intestinal mucosa of CD patients.19–21 Moreover, in contrast to the failure of anti-IL-17 therapies,22 anti-IL-23p19 biologicals showed better clinical response and remission rates in CD patients.23 Here, IL17A is linked to autoimmune disease.