Induction of Th1 and Th17 can be triggered by segmented filamentous bacteria in mice.110 These adherent bacteria can induce the production of IL-8/CCL20 chemokines and feedback the inflammatory response.111 Moreover, a biased microbiota-reactive Th17 response has been observed in IBD patients with a higher production of IL-17A.112 Blocking of IL-17A in CD patients has been showed to rise disease symptoms.113. Here, IL17A is linked to Cowden disease.