Regulation of the intestinal barrier by nutrients: The role of tight junctions

Abstract

Tight junctions (TJs) play an important role in intestinal barrier function. TJs in intestinal epithelial cells are composed of different junctional molecules, such as claudin and occludin, and regulate the paracellular permeability of water, ions, and macromolecules in adjacent cells. One of the most important roles of the TJ structure is to provide a physical barrier to luminal inflammatory molecules. Impaired integrity and structure of the TJ barrier result in a forcible activation of immune cells and chronic inflammation in different tissues. According to recent studies, the intestinal TJ barrier could be regulated, as a potential target, by dietary factors to prevent and reduce different inflammatory disorders, although the precise mechanisms underlying the dietary regulation remain unclear. This review summarizes currently available information on the regulation of the intestinal TJ barrier by food components.

Keywords: intestinal barrier; intestinal permeability; nutrient; tight junction.

FIGURE 1

Anatomy of the intestinal barrier. Intestinal epithelial cells constitute a biochemical and physical barrier to the diffusion of pathogens, toxins, and allergens from the intestinal lumen to the mucosal tissues (left panel). The intestinal barrier system depends on interactions among several barrier components, including the adhesive mucous gel layer, immunoglobulin A, antimicrobial peptides, and intercellular tight junctions (TJs). TJs are formed by a multiple‐protein complex located in the apical portion of the lateral membrane of epithelial cells (right panel). The TJ structure comprises transmembrane proteins, such as claudin, occludin, and junctional adhesion molecule‐A (JAM‐A), and intracellular plaque proteins, such as zonula occludens (ZOs) and cingulin. The interaction between extracellular regions of the transmembrane proteins in adjacent cells regulates the paracellular passage of molecules