Étude de l’effet de l’antithrombine-III (AT-III) sur les modifications de l’épithélium intestinal liées à l’ictère obstructif : étude expérimentale chez le rat

CANDIDATE GENES FOR LIMITING CHOLESTATIC INTESTINAL INJURY IDENTIFIED BY GENE EXPRESSION PROFILING

The lack of bile flow from the liver into the intestine can have devastating complications including hepatic failure, sepsis and even death. This pathologic condition known as cholestasis can result from etiologies as diverse as total parenteral nutrition (TPN), hepatitis and pancreatic cancer. The intestinal injury associated with cholestasis has been shown to result in decreased intestinal resistance, increased bacterial translocation and increased endotoxemia. Anecdotal clinical evidence suggests a genetic predisposition to exaggerated injury. Recent animal research on two different strains of inbred mice demonstrating different rates of bacterial translocation with different mortality rates supports this premise. In this study, a microarray analysis of intestinal tissue following common bile duct ligation (CBDL) performed under general anesthesia on these same two strains of inbred mice was done with the goal of identifying the potential molecular mechanistic pathways responsible. Over 500 genes were increased more than 2.0 fold following CBDL. The most promising candidate genes included MUPs, Serpina1a and LCN-2. RT-PCR validated the microarray results for these candidate genes. In an in vitro experiment using differentiated intestinal epithelial cells, inhibition of MUP-1 by siRNA resulted in increased intestinal epithelial cell permeability. Diverse novel mechanisms involving the growth hormone pathway, the acute phase response and the innate immune response are thus potential avenues for limiting cholestatic intestinal injury. Changes in gene expression were at times found to be not only due to the CBDL but also due to the murine strain. Should further studies in cholestatic patients demonstrate inter-individual variability similar to what we have shown in mice, then a "personalized medicine" approach to cholestatic patients may become possible.

Prostaglandin E1 maintains structural integrity of intestinal mucosa and prevents bacterial translocation during experimental obstructive jaundice

The absence of bile in the gut lumen induces mucosal injury and promotes bacterial translocation (BT). Prostaglandin E (PGE) has a protective effect on the mucosal layer of the alimentary tract. We hypothesize that PGE1 may prevent BT by its beneficial action on the mucosa of the small bowel. Thirty Wistar albino rats were divided equally into 3 groups; Group 1 (control) underwent sham laparotomy, group 2 obstructive jaundice (OJ) and group 3 (OJ + PGE1) underwent common bile duct (CBD) ligation and transection. Groups 1 and 2 received; 1 mL normal saline and group 3 received 40 mg of the PGE1 analogue misoprostol dissolved in 1 mL normal saline administered by orogastric tube once daily. After 7 days, laparotomy and collection of samples for laboratory analyses were performed, including bacteriological analysis of intestine, mesenteric lymph nodes (MLNs), and blood, and histopathologic examination of intestinal mucosa to determine mucosal thickness and structural damage. Serum bilirubin and alkaline phosphatase levels confirmed OJ in all animals with CBD transection. The mucosal damage score was significantly reduced in jaundiced animals receiving PGE1 compared to jaundiced controls (2.15 +/- 0.74 vs 5.3 +/- 0.59; p < .00001) and mucosal thickness was greater (607 +/- 59.1 microm vs. 393 +/- 40.3 microm; p < .00001). The incidence of BT to MLNs decreased from 90% to 30% (p < .02) when jaundiced rats received PGE1. PGE1 treatment reduced the detection rate of viable enteric bacteria in the blood from 60% to 10% (p < .057). We conclude that administration of PGE1 provides protection against OJ-induced atrophy and damage of intestinal mucosa, and thereby prevents translocation of enteric bacteria to underlying tissues.