BDNF and inflammatory bowel disease: Available evidence suggests that the course of IBD might be heavily influenced by this protein group; p75NTR and TrkB are expressed in the gastrointestinal tract, the gut–brain axis allows for communication between the gut and the CNS, and the BDNF pathway is involved in regulation of the serotonergic signaling, which could be implicated in the pathophysiology of IBD [36].