Review
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Pathophysiol. Dec 12, 2020; 11(6): 114-130
Published online Dec 12, 2020. doi: 10.4291/wjgp.v11.i6.114
Clinical relevance of intestinal barrier dysfunction in common gastrointestinal diseases
Andreas Muehler, Jason R Slizgi, Hella Kohlhof, Manfred Groeppel, Evelyn Peelen, Daniel Vitt
Andreas Muehler, Jason R Slizgi, Hella Kohlhof, Manfred Groeppel, Evelyn Peelen, Daniel Vitt, Immunic, AG, Gräfelfing 82166, Germany
Author contributions: Muehler A, Slizgi JR, Kohlhof H, Groeppel M, Peelen E, and Vitt D reviewed and evaluated the literature for inclusion in the review in different therapeutic areas; Muehler A and Slizgi JR prepared the initial draft of the manuscript; Muehler A, Slizgi JR, Kohlhof H, Groeppel M, Peelen E and Vitt D reviewed, edited and approved the final version of the manuscript.
Conflict-of-interest statement: Dr. Muehler and other co-authors report a relationship with Immunic AG (stock, stock options, employment), with drug development projects relevant to this work. In addition, Immunic AG has licensed patent WO 2008/138943 A2 which is part of the development projects in the area of gastrointestinal diseases. Other authors have no conflicts of interest.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Andreas Muehler, MD, Chief Medical Officer, Immunic, AG, Lochhamer Schlag 21, Gräfelfing 82166, Germany. andreas.muehler@imux.com
Received: July 21, 2020
Peer-review started: July 21, 2020
First decision: September 24, 2020
Revised: October 7, 2020
Accepted: October 26, 2020
Article in press: October 26, 2020
Published online: December 12, 2020
Processing time: 143 Days and 5.8 Hours
Abstract

The intestinal barrier is a complex and well-controlled physiological construct designed to separate luminal contents from the bowel wall. In this review, we focus on the intestinal barrier’s relationship with the host’s immune system interaction and the external environment, specifically the microbiome. The bowel allows the host to obtain nutrients vital to survival while protecting itself from harmful pathogens, luminal antigens, or other pro-inflammatory factors. Control over barrier function and the luminal milieu is maintained at the biochemical, cellular, and immunological level. However, disruption to this highly regulated environment can cause disease. Recent advances to the field have progressed the mechanistic understanding of compromised intestinal barrier function in the context of gastrointestinal pathology. There are numerous examples where bowel barrier dysfunction and the resulting interaction between the microbiome and the immune system has disease-triggering consequences. The purpose of this review is to summarize the clinical relevance of intestinal barrier dysfunction in common gastrointestinal and related diseases. This may help highlight the importance of restoring barrier function as a therapeutic mechanism of action in gastrointestinal pathology.

Keywords: Intestinal barrier; Microbiome; Gastrointestinal disease; Inflammatory bowel disease; Inflammatory bowel syndrome; Colitis

Core Tip: Intestinal barrier dysfunction is an underlying pathophysiological feature in many gastrointestinal diseases. Understanding barrier dysfunction may help drive a deeper understanding of gastrointestinal pathology and identify novel way(s) to manage and/or treat disease. Here, we summarize the evidence supporting intestinal barrier dysfunction in common immune-mediated gastrointestinal diseases and its clinical relevance.