Review
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World J Gastrointest Pathophysiol. Feb 15, 2014; 5(1): 18-32
Published online Feb 15, 2014. doi: 10.4291/wjgp.v5.i1.18
Intestinal barrier: A gentlemen’s agreement between microbiota and immunity
Andrea Moro Caricilli, Angela Castoldi, Niels Olsen Saraiva Câmara
Andrea Moro Caricilli, Angela Castoldi, Niels Olsen Saraiva Câmara, Department of Immunology, University of Sao Paulo, São Paulo, SP 05508-900, Brazil
Niels Olsen Saraiva Câmara, Department of Medicine, Federal University of Sao Paulo, Sao Paulo, SP 05508-900, Brazil
Author contributions: All the authors contributed equally in the writing of this manuscript.
Correspondence to: Niels Olsen Saraiva Câmara, Professor, Department of Medicine, Federal University of Sao Paulo, Avenida Lineu Prestes, 1730, Cidade Universitária, Sao Paulo, SP 05508-900, Brazil. niels@icb.usp.br
Telephone: +55-11-30917388 Fax: +55-11-30917224
Received: July 6, 2013
Revised: November 26, 2013
Accepted: January 13, 2014
Published online: February 15, 2014
Processing time: 229 Days and 11.8 Hours
Abstract

Our body is colonized by more than a hundred trillion commensals, represented by viruses, bacteria and fungi. This complex interaction has shown that the microbiome system contributes to the host’s adaptation to its environment, providing genes and functionality that give flexibility of diet and modulate the immune system in order not to reject these symbionts. In the intestine, specifically, the microbiota helps developing organ structures, participates of the metabolism of nutrients and induces immunity. Certain components of the microbiota have been shown to trigger inflammatory responses, whereas others, anti-inflammatory responses. The diversity and the composition of the microbiota, thus, play a key role in the maintenance of intestinal homeostasis and explain partially the link between intestinal microbiota changes and gut-related disorders in humans. Tight junction proteins are key molecules for determination of the paracellular permeability. In the context of intestinal inflammatory diseases, the intestinal barrier is compromised, and decreased expression and differential distribution of tight junction proteins is observed. It is still unclear what is the nature of the luminal or mucosal factors that affect the tight junction proteins function, but the modulation of the immune cells found in the intestinal lamina propria is hypothesized as having a role in this modulation. In this review, we provide an overview of the current understanding of the interaction of the gut microbiota with the immune system in the development and maintenance of the intestinal barrier.

Keywords: Microbiota; Immune system; Lamina propria; Intestinal barrier

Core tip: Each of our bodies is colonized by more than a hundred trillion commensals, which include viruses, bacteria and fungi. The association between microbiota and their hosts is complex and has important repercussions for both. The diversity and the composition of the microbiota thus play a key role in the maintenance of intestinal homeostasis and the induction of immunity. These features partially explain the link between alterations in intestinal microbiota and gut-related disorders in humans. In this review, we provide an overview of the current understanding of the interaction between gut microbiota and the immune system in the development and maintenance of the intestinal barrier.