The etiology of inflammatory bowel disease (IBD) remains unknown. However, it has been postulated that IBD patients have a disruption of the intestinal barrier integrity that facilitates the trigger of an intestinal pathological process after exposure to several exogenous antigens. Barrier function is highly regulated, allowing the epithelium to control transmucosal permeability to solutes, water, and electrolytes. Occludin (OCLN) has a large cytoplasmic extension that may coordinate with the tight junctional complex, comprising a large number of membrane-associated proteins. OCLN is the first integral tight junction protein and the most ubiquitously expressed at the apical-most membranes.
Yamamoto-Furusho, J., Mendivil-Rangel, E., & Fonseca-Camarillo, G. (2012). Differential expression of occludin in patients with ulcerative colitis and healthy controls. Inflammatory Bowel Diseases, 18(10), E1999. doi:10.1002/ibd.22835