Altered permeability in inflammatory bowel disease: pathophysiology and clinical implicationsMankertz, Joachim; Schulzke, Jörg-DieterCurrent Opinion in Gastroenterology: July 2007 - Volume 23 - Issue 4 - p 379–383 doi: 10.1097/MOG.0b013e32816aa392 Inflammatory bowel disease Buy Abstract Author InformationAuthors Article MetricsMetrics Purpose of review To present the mechanisms behind barrier disturbance in inflammatory bowel disease and their functional consequences. Recent findings A reduction in tight junction strands, strand breaks and alteration of tight junction protein content and composition characterize Crohn's disease. In ulcerative colitis, epithelial leaks appear early as a result of microerosions, upregulated epithelial apoptosis and tight junction protein changes with pronounced increases in claudin-2. T-helper type 1 cytokine effects by interferon-γ and tumour necrosis factor α are important for epithelial damage in Crohn's disease. Interleukin-13 is the key effector cytokine in ulcerative colitis, stimulating epithelial cell apoptosis, and can upregulate claudin-2 expression. Together with interleukin-13-induced epithelial restitution arrest, this may explain why ulcer lesions occur in early stages of ulcerative colitis but are only observed in advanced inflammatory stages in Crohn's disease. Summary Barrier dysfunction in inflammatory bowel disease contributes to diarrhea by a leak flux mechanism and can cause mucosal inflammation secondary to luminal antigen uptake. Barrier abnormalities, such as epithelial tight junction changes and apoptotic leaks, gross mucosal lesions, and epithelial restitution arrest are responsible for these abnormalities and are the result of immune dysregulation. Studying the underlying mechanisms is important in understanding the pathophysiology of inflammatory bowel disease and developing therapeutic strategies. Department of Gastroenterology, Infectious Diseases and Rheumatology, Charité – Campus Benjamin Franklin, Berlin, Germany Correspondence to Prof. Dr Jörg-Dieter Schulzke, Med. Klinik I, Charité – Campus Benjamin Franklin, 12200 Berlin, Germany Tel: +49 30 8445 2666; fax: +49 30 8445 4493; e-mail: firstname.lastname@example.org © 2007 Lippincott Williams & Wilkins, Inc.