Duodenojejunal Bypass Leads to Altered Gut Microbiota and Strengthened Epithelial Barriers in Rats

Abstract

Background: Gastrointestinal bypass changes the gut microbiota and decreases systemic endotoxemia in obese subjects. Epithelial barrier integrity is crucial for confining enteric bacteria in the lumen and preventing gut-derived endotoxemia. The effect of bypass surgery on intestinal barrier functions remains poorly understood. This study aimed to evaluate the changes in intestinal permeability and gut barrier between rats receiving Roux-en-Y duodenojejunal bypass (DJB) or sham operation (SO). Methods: Eighteen Sprague–Dawley rats were assigned to DJB or SO groups. Tissues of the alimentary, biliopancreatic, and common limbs in the small intestine, and the colon, were collected 2 weeks after operation. Mucosa-associated bacteria were quantified by colony forming units. Intestinal permeability was determined by mucosal-to-serosal dextran flux measured in Ussing chambers. Expression of occludin and proliferating cell nuclear antigen (PCNA) in the intestinal mucosa was examined by western blots. Results: Enteric bacterial numbers were increased in the alimentary and common limbs after DJB. Reduced dextran permeability was found in the alimentary limb, common limb, and colon after DJB. Moreover, increased villus height and crypt depth were found to be associated with higher mucosal levels of occludin and PCNA levels in the alimentary and common limbs after DJB. Conclusions: DJB in rats altered gut microbiota and reduced intestinal permeability due to increased epithelial proliferation and tight junctional protein expression. Our results show that bypass surgery led to fortification of the intestinal barrier functions, which may provide an explanation for the decreased risk of systemic endotoxemia in postoperative patients.