OCLN and Cowden disease: In this study, the OD values of occludin in the terminal ileum and ileocecal area of the mild active CD and ileocecal area of moderate-to-severe active CD after short-chain polypeptide-based EEN feeding combined with drug treatment were significantly higher than those in the drug group, which suggests that the short-chain polypeptide-based EEN combined with drug regimens have more efficacy in alleviating gut damage and promoting mucosal healing of active CD than that of drug regimens alone.