Combined effects of tauroursodeoxycholic Acid and glutamine on bacterial translocation in obstructive jaundiced rats:

Role and significance of bile acid membrane receptor GPBAR1 in pathogenesis of obstructive jaundice

GPBAR1 is the first confirmed G protein coupled bile acid membrane receptor, which is widely expressed in the liver, gallbladder, kidney, intestine, and the nervous and cardiovascular systems. During the development of obstructive jaundice (OJ), GPBAR1 is activated by bile acid signal and mediates different signal transduction pathways, thus playing a corresponding role in the pathogenesis of OJ. GPBAR1 may be a potential therapeutic target for the treatment of OJ by controlling inflammation, regulating the function of bile duct epithelial barrier, inhibiting renal oxidative stress, and regulating intestinal mucosal barrier and intestinal flora, pruritus and sensory disturbance, and cardiovascular function. This article reviews the role and signficance of GPBAR1 in the pathogenesis of OJ.

Modulation of the Unfolded Protein Response by Tauroursodeoxycholic Acid Counteracts Apoptotic Cell Death and Fibrosis in a Mouse Model for Secondary Biliary Liver Fibrosis

The role of endoplasmic reticulum stress and the unfolded protein response (UPR) in cholestatic liver disease and fibrosis is not fully unraveled. Tauroursodeoxycholic acid (TUDCA), a hydrophilic bile acid, has been shown to reduce endoplasmic reticulum (ER) stress and counteract apoptosis in different pathologies. We aimed to investigate the therapeutic potential of TUDCA in experimental secondary biliary liver fibrosis in mice, induced by common bile duct ligation. The kinetics of the hepatic UPR and apoptosis during the development of biliary fibrosis was studied by measuring markers at six different timepoints post-surgery by qPCR and Western blot. Next, we investigated the therapeutic potential of TUDCA, 10 mg/kg/day in drinking water, on liver damage (AST/ALT levels) and fibrosis (Sirius red-staining), in both a preventive and therapeutic setting. Common bile duct ligation resulted in the increased protein expression of CCAAT/enhancer-binding protein homologous protein (CHOP) at all timepoints, along with upregulation of pro-apoptotic caspase 3 and 12, tumor necrosis factor receptor superfamily, member 1A (TNFRsf1a) and Fas-Associated protein with Death Domain (FADD) expression. Treatment with TUDCA led to a significant reduction of liver fibrosis, accompanied by a slight reduction of liver damage, decreased hepatic protein expression of CHOP and reduced gene and protein expression of pro-apoptotic markers. These data indicate that TUDCA exerts a beneficial effect on liver fibrosis in a model of cholestatic liver disease, and suggest that this effect might, at least in part, be attributed to decreased hepatic UPR signaling and apoptotic cell death.

L-carnitine reduces acute lung injury in experimental biliary obstruction

OBJECTIVES

To investigate the protective effects of L-carnitine (LC) on lungs in an experimental obstructive jaundice (OJ) model.

METHODS

This was conducted for 2 months between May 2011 and July 2011 at Suleyman Demirel University School of Medicine Experimental and Clinical Research Center, Isparta, Turkey. Thirty-eight Wistar-Albino rats with an average weight of 250-300 g were divided into 3 groups of control, OJ, and OJ + L-carnitine treatment (LCT). L-carnitine was injected intravenously into the tail vein at a dose of 50 mg/kg/day for 10 days to the LCT group. Animals were sacrificed 10 days later. Enzyme levels were measured in the lung tissue; malondialdehyde, myeloperoxidase (MPO), glutathione peroxidase (GSH-Px), catalase, and superoxide dismutase. Tumor necrosis factor-alfa, interleukin 6 (IL-6), IL-8, and C-reactive protein levels were studied in plasma samples. Histopathological changes in the lungs were examined. 

RESULTS

There was a decreased in GSH-Px, MPO, and IL-8 levels (p less than 0.05) in the LCT group. The histopathological examination showed that neutrophil leukocyte infiltration and edema formation decreased and destruction of lung parenchyma disappeared following the treatment with LC (p less than 0.05). 

CONCLUSION

L-carnitine has a protective effect against lung damage due to experimental obstructive jaundice, possibly by altering anticytokine and antioxidant activity, and by decreasing the neutrophil migration.

Establishment and evaluation of a rat model of reversible obstructive jaundice

AIM: To establish a rat model of reversible obstructive jaundice and to evaluate its clinical practical value.

METHODS: Thirty-two Wistar rats were randomly divided into a reversible obstructive jaundice group (ROJ) and an obstructive jaundice group (OJ). In the ROJ group, bile duct obstruction was induced by ligation of the bile duct and a PICC catheter in parallel. After 5 d, the PICC catheter was pulled out to allow the recanalization of the bile duct. In the OJ group, complete obstructive jaundice was induced. Eight rats from each group were sacrificed on days 5 and 8, respectively, which were designated as ROJ5, ROJ8, OJ5 and OJ8, respectively. Serum total bilirubin (TBIL), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) levels were measured before operation and on days 5, 6 and 8 after operation. Intestinal mucosal tissue samples were taken and stained with hematoxylin and eosin to observe the changes in intestinal mucosal morphology and damage.

RESULTS: The changes in serum TBIL, ALT and ALP in the ROJ5 group were similar to those in the OJ5 group on day 5 after the model establishment, and there was no difference in liver function parameters between the two groups at each time point. Three days after the catheter was removed in the ROJ group, serum levels of TBIL, ALT and ALP quickly recovered, and the damage of the intestinal mucosa was significantly reduced. The intestinal mucosal injury index in the ROJ8 group was significantly lower than that in the OJ8 group.

CONCLUSION: The rat model of reversible obstructive jaundice developed by "ligation of the bile duct and removal of support catheter" is a stable and reliable animal model.

Effect of glutamine enriched nutrition support on gut barrier of rats with obstructive jaundice: A Meta-analysis

AIM: To systematically assess the effect of glutamine enriched enteral nutrition support on the gut barrier of rats with obstructive jaundice (OJ).

METHODS: Databases including PubMed, Embase, High Wire and Cochrane Central Register of Controlled Trials were searched using keywords "glutamine", "obstructive jaundice". Literature published before November 2014 was searched. Randomized controlled trials comparing conventional treatment and glutamine enriched nutrition support were enrolled in the study, and then the literature was screened and the data were extracted by two independent reviewers. The quality of the literature was assessed, and the data were analyzed using the RevMan4.2 software. Count data were analyzed using relative risk (RR) and 95% confidence interval (95%CI), and measurement data were analyzed using standard mean difference (SMD) or weighted mean difference (WMD) and 95%CI. The heterogeneity of the data was analyzed using the I² test.

RESULTS: Eight articles including 152 cases were enrolled in the study, and all of them were prospective randomized controlled studies. There were 76 rats treated by conventional methods (control group) and 76 rats receiving glutamine enriched nutrition support (experimental group). Compared with the control group, glutamine enriched nutrition support could decrease the rates of bacterial translocation (BT) to mesenteric lymph nodes (MLNs), the liver, spleen and blood (RR = 0.34, 0.36, 0.38, 0.30, P < 0.05), and enhance the antioxidant capacity of the intestinal mucosa (WMD_MPO = -0.44, WMD_MDA = -57.87; 95%CI: -0.85--0.03, -104.14--11.60; P < 0.05), but could not significantly improve the liver dysfunction and intestinal villi.

CONCLUSION: Glutamine enriched nutrition support has a protective effect on intestinal barrier function in rats with OJ in terms of reducing BT effectively and enhancing the antioxidant capacity of the intestinal mucosa significantly.