The Effect of Endotoxin on Intestinal Mucosal Permeability to Bacteria In Vitro

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Abstract
Objective: To examine the role of the intestinal mucosa in bacterial translocation, in vitro bacterial passage across ileal mucosal segments mounted in Ussing chambers were studied in control and endotoxin (lipopolysaccharide)-treated rats. Design: Experimental study. Materials and Methods: Three groups of rats were studied. The experimental group received an intraperitoneal injection of lipopolysaccharide, while controls received an equivalent volume of saline solution; a third group received no treatment. Twenty-four hours later, all groups underwent laparotomy and organ culture to assess bacterial translocation. At the same time, a segment of mucosa from the terminal ileum of each animal was mounted in a Ussing chamber, and the transmucosal passage of labeled Escherichia coli from the luminal to serosal surface was assessed by results of serial cultures. Results: In vivo bacterial translocation occurred in 100% of the lipopolysaccharide-treated animals, significantly higher than the incidence seen in controls (25%; P<.05). In vitro passage of labeled E coli across ileal mucosa in the Ussing chamber occurred in 78% of lipopolysaccharide-treated animals, while in controls transmucosal passage was seen in only 14% (P<.05). Histologic examination of mucosa from both groups using light and transmission electron microscopy demonstrated no structural differences between groups. Conclusion: Increased permeability to bacteria at the mucosal level contributes to the bacterial translocation seen in endotoxemia. (Arch Surg. 1995;130:53-58)