IL17A and irritable bowel syndrome: They observed, amongst increased presence of several other pro-inflammatory cytokines, that IL-17 was significantly increased in IBS samples.82In situ immunohistochemical stainings on descending and rectosigmoid biopsies confirmed enhanced presence of Th17 cells in IBS patients as compared to controls.83 Interestingly, using TRPV1-Ai32 optogenetic mice and cutaneous light stimulation it could be shown that activation of TRPV1+ neurons is sufficient to elicit, via CGRP-release, a Th17 response.