Shedding-induced gap formation contributes to gut barrier dysfunction in endotoxemia

BACKGROUND: The intestinal mucosa exhibits high turnover rates with a balance of shedding and the migration of epithelial cells to maintain gut barrier function. Systemic diseases such as sepsis and major thermal injury accelerate the rate of cell shedding, subsequent gap formation, and gut barrier dysfunction. However, the detailed changes of intestinal villi in barrier dysfunction have not been well described. METHODS: In this study, intestinal barrier dysfunctions were induced through the injection of lipopolysaccharide (LPS) in C57BL/6 mice. Intravital images of the small intestine were observed with multiphoton microscopy for cellular dynamics analysis. The changes of epithelial cells shedding, gap formation, goblet cells, and intestinal leaks were observed, calculated, and analyzed. RESULTS: Endotoxemia enhanced chromatin condensation, accelerated migration, and increased the shedding of intestinal epithelial cells compared with the control group. Furthermore, LPS-induced shedding resulted in gap formation and subsequent intestinal leaks. In total, 40% of intestinal leaks were through gaps, and 60% were through paracellular spaces. Although LPS injection significantly increased the leaks in gaps and paracellular spaces, it did not change the percentage of leaks in gaps and paracellular spaces compared with the control group. CONCLUSION: We conclude that endotoxemia causes gut barrier dysfunction by increasing epithelium shedding, gaps, and intestinal leaks. However, the effect of the impairment of local barrier maintenance on the distribution of intestinal leaks in gaps and paracellular spaces is minimal. (J Trauma Acute Care Surg. 2013;74: 203-213. Copyright (C) 2013 by Lippincott Williams & Wilkins)