Role of Intestinal Permeability in Monitoring Mucosal Barrier Function

Abstract

The intestinal barrier function is considered to play an important role in protecting the penetration of luminal antigens, associated with the development of secondary infection and sepsis and the initiation of the multiple organ dysfunction syndrome. The intestinal mucosal barrier against luminal macromolecules and microorganisms consists of both non-immunological and immunological defence mechanisms. The main constituents of the intestinal barrier are the endothelial and epithelial barriers. The epithelial barrier selectively restricts micromolecular permeation and almost completely restricts macromolecular permeation, while the endothelial barrier has a very limited restriction to micromolecules and only partly to macromolecules. Maintenance of the barrier depends on the integrity of cellular plasma membranes and tight junctions, as well as the elaboration of endothelial and epithelial secretory products. Focal denudation of the barrier results in permeation of potentially threatening luminal compounds including antigens, proteases, H⁺, bacteria and endotoxin, and also other factors chemotactic for inflammatory cells. By initiating inflammation and thus acting on subepithelial tissues, such factors can further influence endothelial and epithelial transport and barrier function. The repair of endothelial and epithelial injury is also complex, and both restitution and enhanced endothelial and epithelial cell proliferation are likely to be important. At present, however, mechanisms for intestinal epithelial and endothelial permeation, their alterations in disease and potential ways to prevent or repair injury, are still not fully elucidated.

Early endothelial damage and increased colonic vascular permeability in the development of experimental ulcerative colitis in rats and mice

“…20 Intestinal permeability is influenced not only by the epithelial but also by the microvascular endothelial barriers. 21 Our laboratory was the first to demonstrate that microvascular Endothelial damage in ulcerative colitis G Tolstanova et al injury, leading to increased VP and capillary stasis, precedes the development of mucosal erosions and ulcers in the stomach and duodenum. 22,23 Recent publications on the role of intestinal permeability mostly focus on disrupted epithelial barrier integrity in the pathogenesis of UC.…”

Effects of yeast products on the intestinal morphology, barrier function, cytokine expression, and antioxidant system of weaned piglets

“…The epithelium of the intestinal mucosa acts as a physical barrier that helps to block pathogens, while allowing dietary nutrients to enter the body (Sun et al, 1998). An intact intestinal mucosal barrier is therefore very important for proper intestinal function.…”

Sucrose Co-administration Reduces the Toxic Effect of Lectin on Gut Permeability and Intestinal Bacterial Colonization

“…The ratio of lactulose vs. mannitol recovered (L/M ratio) was used as a measure of intestinal permeability. A high L/M ratio indicated greater intestinal permeability and therefore greater disruption of the intestinal barrier [17].…”