Concerning TGF-β1, evidence has shown enhanced levels of this protein in blood and mucosa of IBD patients.104–106 Interestingly, beyond its role in tissue fibrosis and immune regulation,107 TGF-β1 is positively involved in inflammatory pain signaling.108–111 Mechanisms of action could involve sensitization of TRPV1 or augmented production of substance P in sensory neurons,109,112,113 demonstrating a potential role for TGF-β1 in neuronal hyperexcitability as well. Here, TAC1 is linked to irritable bowel syndrome.