Effect of the administration of fermentable and non-fermentable dietary fibre on intestinal bacterial translocation in ascitic cirrhotic rats

Comparison of Two Protocols of Carbon Tetrachloride-Induced Cirrhosis in Rats - Improving Yield and Reproducibility

Despite being a cardinal experimental model, the induction of cirrhosis in rats by repeated exposure to carbon tetrachloride (CCl4) has low reproducibility. Here, we compared two models of cirrhosis induced by orogastric administration of CCl4 once (CCl4-1xWk) or twice a week (CCl4-2xWk) for 12 weeks in male Sprague-Dawley rats. Control rats received water instead of CCl4. Both CCl4 protocols similarly attenuated body weight gain (p < 0.01 vs. Control). Although both CCl4 protocols increased hepatic fibrosis, portal hypertension and splenomegaly, the magnitude of these alterations was higher and more consistent in CCl4-2xWk rats. Importantly, two CCl4-1xWk rats did not develop cirrhosis versus a 100% yield of cirrhosis in CCl4-2xWk rats. The CCl4-2xWk protocol consistently induced liver atrophy together with hematological, biochemical and coagulation abnormalities characteristic of advanced cirrhosis that were absent in CCl4-1xWk rats. Ascites occurred in 20% and 80% of rats in theCCl4-1xWk and CCl4-2xWk groups (p < 0.01). All rats showed normal renal function, arterial blood gases and stable systemic hemodynamics. The total dose of CCl4 and mortality rate were similar in both protocols. The CCl4-2xWk protocol, therefore, was highly reproducible and effective for the induction of experimental cirrhosis within a confined time, representing a valuable advance for liver research.

Endoscopic shielding technique with a newly developed hydrogel to prevent thermal injury in two experimental models

BACKGROUND AND AIM

A newly developed hydrogel, applied through the endoscope as an endoscopic shielding technique (EndoSTech), is aimed to prevent deep thermal injury and to accelerate the healing process of colonic induced ulcers after therapeutic endoscopy.

METHODS

Lesions were performed in rats (n = 24) and pigs (n = 8). Rats were randomized to receive EndoSTech (eight rats each) with: saline (control), hyaluronic acid and product. In pigs, three ulcer sites were produced in each pig: endoscopic mucosal resection (EMR)-ulcer with prior saline injection (A; EMR-saline), EMR-saline plus EndoSTech with product (B; EMR-saline-P), and EMR with prior injection of product plus EndoSTech-P (C; EMR-P-P). At the end of the 14-day study, the same lesions were performed again in healthy mucosa to assess acute injury. Animals were sacrificed after 7 (rats) and 14 (pigs) days. Ulcers were macroscopically and histopathologically evaluated. Thermal injury (necrosis) was assessed with a 1-4 scale.

RESULTS

In rats, treatment with product improved mucosal healing comparing with saline and hyaluronic acid (70% vs 30.3% and 47.2%; P = 0.003), avoiding mortality (0% vs 50% and 25%; P = 0.038), and perforation (0% vs 100% and 33.3%; P = 0.02); respectively. In pigs, submucosal injection of product induced a marked trend towards a less deep thermal injury (C = 2.25-0.46 vs A and B = 2.75-0.46; P = 0.127). Mucosal healing rate was higher with product (B = 90.2-3.9%, C = 91.3-5.5% vs A = 73.1-12.6%; P = 0.002).

CONCLUSIONS

This new hydrogel demonstrates strong healing properties in preclinical models. In addition, submucosal injection of this product is able to avoid high thermal load of the gastrointestinal wall.

Antibiotic prophylaxis in cirrhosis: Good and bad

Patients with cirrhosis, particularly those with decompensated cirrhosis, are at increased risk of bacterial infections that may further precipitate other liver decompensations including acute-on-chronic liver failure. Infections constitute the main cause of death in patients with advanced cirrhosis, and strategies to prevent them are essential. The main current strategy is the use of prophylactic antibiotics targeted at specific subpopulations at high risk of infection: prior episode of spontaneous bacterial peritonitis, upper gastrointestinal bleeding, and low-protein ascites with associated poor liver function. Antibiotic prophylaxis effectively prevents not only the development of bacterial infections in all these indications but also further decompensation (variceal bleeding, hepatorenal syndrome) and improves survival. However, antibiotic prophylaxis is also associated with a clinically relevant and increasing drawback, the development of infections due to multidrug-resistant organisms. Several strategies have been suggested to balance the risks and benefits of antibiotic prophylaxis.

CONCLUSION

Antibiotic stewardship principles such as the restriction of antibiotic prophylaxis to subpopulations at a very high risk for infection, the avoidance of antibiotic overuse, and early deescalation policies are key to achieve this balance; nonantibiotic prophylactic measures such as probiotics, prokinetics, bile acids, statins, and hematopoietic growth factors could also contribute to ameliorate the development and spread of multidrug-resistant bacteria in cirrhosis. (Hepatology 2016;63:2019-2031).

Host species-specific translocation of Escherichia coli

The purpose of this paper is to investigate the rate of translocation of Escherichia coli strains in different experimental/animal models. Four proficient translocating E. coli strains isolated from mesenteric lymph nodes (MLNs) and/or the blood of rats (strains KIC-1 and KIC-2), from a fatal case of pancreatitis (HMLN-1) and from pigs (PC-1 isolated in this study) were tested for their ability to translocate across two host species and the Caco-2 cell line as a model of the human gut epithelium. HMLN-1 was found in the MLNs of all 15 pigs tested. This strain, however, did not translocate in any rats and only colonised the caecum of four rats in small numbers. HMLN-1 and PC-1 were the dominant translocating strains in Caco-2 cells compared to KIC-1 and KIC-2, which were found to translocate at a lower rate in pigs and in Caco-2 cells. The rate of translocation of PC-1 in rats was also very low compared to KIC-1 and KIC-2. We suggest that, in studies aiming to investigate the mechanism of translocation of E. coli strains isolated from humans, rats may not be an appropriate animal model and that the Caco-2 cells or pigs are more suitable in vitro and in vivo models, respectively.