OCLN and irritable bowel syndrome: The red cluster is related to the pathophysiological mechanism of IBS, intestinal permeability, visceral sensitivity, and inflammation-immune-neural interactions, including increased expression of endocrine cells and T lymphocytes [26] in PI-IBS, downregulation of tight junction (TJ) proteins ZO-1, occludin, and claudin-1 in IBS-D [27–29], as well as VH associated with dysfunction of the 5-HT system [27].