Moreover, the expression of tight junction protein ZO-1, Claudin-1, and Occludin in intestinal mucosal epithelial cells decreased, causing an increase in intestinal permeability [27], which leads to the entry of pathogenic microorganisms and harmful substances into the intestinal mucosa, activating immune cells to produce inflammatory responses and further aggravating the development of colitis [28]. This evidence concerns the gene CLDN1 and colitis.