Review
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World J Gastrointest Pathophysiol. Feb 15, 2012; 3(1): 27-43
Published online Feb 15, 2012. doi: 10.4291/wjgp.v3.i1.27
Host-microbial interactions and regulation of intestinal epithelial barrier function: From physiology to pathology
Linda Chia-Hui Yu, Jin-Town Wang, Shu-Chen Wei, Yen-Hsuan Ni
Linda Chia-Hui Yu, Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan, China
Jin-Town Wang, Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan, China
Shu-Chen Wei, Department of Internal Medicine, National Taiwan University Hospital, Taipei 100, Taiwan, China
Yen-Hsuan Ni, Department of Pediatrics, College of Medicine, National Taiwan University Hospital, Taipei 100, Taiwan, China
Author contributions: Yu LC performed the literature review and wrote the paper; Ni YH provided a significant editorial and literature contribution; Wang JT and Wei SC provided literature related comments and review.
Supported by National Science Council, No. NSC99-2628-B-002-008-MY3 and NSC100-2325-B-002-035
Correspondence to: Yen-Hsuan Ni, Professor, Department of Pediatrics, College of Medicine, National Taiwan University Hospital, 7 Chung-Shan South Road, Taipei 100, Taiwan, China. yhni@ntu.edu.tw
Telephone: +886-2-23123456 Fax: +886-2-23938871
Received: April 11, 2011
Revised: October 4, 2011
Accepted: February 8, 2012
Published online: February 15, 2012
Abstract

The gastrointestinal tract is the largest reservoir of commensal bacteria in the human body, providing nutrients and space for the survival of microbes while concurrently operating mucosal barriers to confine the microbial population. The epithelial cells linked by tight junctions not only physically separate the microbiota from the lamina propria, but also secrete proinflammatory cytokines and reactive oxygen species in response to pathogen invasion and metabolic stress and serve as a sentinel to the underlying immune cells. Accumulating evidence indicates that commensal bacteria are involved in various physiological functions in the gut and microbial imbalances (dysbiosis) may cause pathology. Commensal bacteria are involved in the regulation of intestinal epithelial cell turnover, promotion of epithelial restitution and reorganization of tight junctions, all of which are pivotal for fortifying barrier function. Recent studies indicate that aberrant bacterial lipopolysaccharide-mediated signaling in gut mucosa may be involved in the pathogenesis of chronic inflammation and carcinogenesis. Our perception of enteric commensals has now changed from one of opportunistic pathogens to active participants in maintaining intestinal homeostasis. This review attempts to explain the dynamic interaction between the intestinal epithelium and commensal bacteria in disease and health status.

Keywords: Intestinal barrier; Commensal bacteria; Enterocytes; Tight junctions; Lipopolysaccharide; CD14/TLR4; Inflammatory bowel disease; Colorectal cancer