Analysis of the reversibility of biliary cirrhosis in young rats submitted to biliary obstruction

Mechanism of scar formation following Roux-en-Y choledochojejunostomy in a novel rat model of obstructive jaundice

Background

The present study aimed to analyze the scar formation mechanism following Roux-en-Y choledochojejunostomy (CJS) in a novel rat model of obstructive jaundice.

Methods

The biliary obstruction model of Sprague-Dawley (SD) rats was established in advance, and 24 rats were randomly divided into 4 groups (control group, 1-day ligation group, 3-day ligation group, and 5-day ligation group). Changes in postoperative weight, common bile duct diameter, and laboratory indexes were analyzed to determine the best operation time. Roux-en-Y CJS in rats was studied based on the model, and the rats were randomly divided into 4 groups [control group, 3-day choledochojejunostomy (CJS) group, 7-day CJS group, and 30-day CJS group]. The same indexes were analyzed, and the characteristics of scar formation were evaluated by histopathology and polymerase chain reaction examination.

Results

The third day after common bile duct ligation is the best time for a Roux-en-Y CJS. The common bile duct diameter expands to 4.2 mm on average, and these physiological characteristics are consistent with current standard clinical findings. After completing CJS, the rats’ weight returned to normal levels, and alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TB), direct bilirubin (DB), and C-reactive protein (CRP) indexes gradually decreased (P<0.05). Anastomotic stoma diameter tended to narrow with time and was significantly narrower on day 30 than preoperation. After CJS, the expression of α-smooth muscle actin (α-SMA) peaked in the early stage and was still higher than that of the control group in the bile duct wall 1 month postoperatively (P<0.05). Transforming growth factor-β1 (TGF-β1) expression gradually increased and was higher than that of the control group at each stage postoperatively (P<0.05).

Conclusions

The rat Roux-en-Y CJS model is more in line with our surgical model, and the clinical condition has potential applicability for the study of CJS scar formation. Scar formation following CJS in rats is characterized by the activation of fibroblasts caused by early inflammatory stimulation, which leads to the proliferation of collagen and smooth muscle fibers, resulting in scars.

Novel imaging-based approaches for predicting the hepatic venous pressure gradient in a porcine model of liver cirrhosis and portal hypertension

AIMS

Hepatic venous pressure gradient (HVPG) is critical for staging and prognosis prediction of portal hypertension (PH). However, HVPG measurement has limitations (e.g., invasiveness). This study examined the value of non-invasive, imaging-based approaches including magnetic resonance elastography (MRE) and intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) for the prediction of HVPG in a porcine model of liver cirrhosis and PH.

MAIN METHODS

Male Bama miniature pigs were used to establish a porcine model of liver cirrhosis and PH induced by embolization. They were randomly assigned to an experimental group (n = 12) and control group (n = 3). HVPG was examined before and after transjugular intrahepatic portosystemic shunt (TIPS). MRE and IVIM-DWI were performed to obtain quantitative parameters including liver stiffness (LS) in MRE, tissue diffusivity (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) in IVIM-DWI. The correlation between HVPG and the parameters was assessed.

KEY FINDINGS

LS values were significantly greater in the experimental group, while f values were significantly decreased at 4, 8, and 12 weeks after embolization compared to the control group. Furthermore, HVPG was significantly lower immediately after versus before TIPS. In parallel, LS and f values showed significant alterations after TIPS, and these changes were consistent with a reduction in HVPG. Spearman analysis revealed a significant correlation between the parameters (LS and f) and HVPG. The equation was eventually generated for prediction of HVPG.

SIGNIFICANCE

The findings show a good correlation between HVPG and the quantitative parameters; thus, imaging-based techniques have potential as non-invasive methods for predicting HVPG.

Sepsis and cirrhosis in growing animals: description of a new experimental model and its pathological and immunological reliability

OBJECTIVES

In cirrhotic children, infection events and sepsis are more frequent and more severe due to immune dysfunction. The objectives of the current study were therefore to develop an experimental model of infection and sepsis in cirrhotic weaning growing rats, by the use of bile duct ligation (BDL) and cecal ligation and puncture (CLP). Additionally, the correlation of the clinico-histopathological data and serial cytokine levels in septic cirrhotic and non-cirrhotic animals was studied.

METHODS

Young Wistar rats of age 21 days and of weight between 70-90 g were divided into 12 groups according to the surgical procedure performed: sham (sacrificed after 2 or 4 weeks), BDL (sacrificed after 2 or 4 weeks), CLP (2- or 4-week old animals sacrificed after 12 or 24 hours), BDL+CLP (2- or 4-week old animals sacrificed after 12 hours). Histopathological studies and determination of serum levels of cytokines IL-1 beta, IL-10, and TNF-alpha, for studies of systemic infection, were performed. Murine sepsis scores (MSS) based on the clinical aspects just before euthanasia were also included.

RESULTS

A transitory increase in IL-1, IL-10, and TNF-alpha levels was observed, with different patterns according to the groups. Two-hit groups tended to present with higher values of serum cytokines and histopathological scores than their septic non-cirrhotic counterparts. There was a correlation between mortality rate and MSS (p<0.0001).

CONCLUSION

The model is feasible and may be utilized in studies on liver cirrhosis and infection in growing animals.

Does Biliodigestive Anastomosis Have Any Effect on the Reversal of Hepatopulmonary Syndrome in a Biliary Cirrhosis Experimental Model?

BACKGROUND

Biliary cirrhosis is associated with hepatopulmonary syndrome (HPS), which is related to increased posttransplant morbidity and mortality.

AIMS

This study aims to analyze the pathophysiology of biliary cirrhosis and the onset of HPS.

METHODS

Twenty-one-day-old Wistar rats were subjected to common bile duct ligation and were allocated to two groups: group A (killed 2, 3, 4, 5, or 6 weeks after biliary obstruction) and group B (subjected to biliodigestive anastomosis 2, 3, 4, 5, or 6 weeks after the first procedure and killed 3 weeks later). At the killing, arterial blood was collected for the analyses, and samples from the liver and lungs were collected for histologic and molecular analyses. The gasometric parameters as well as the expression levels of ET-1, eNOS, and NOS genes in the lung tissue were evaluated.

RESULTS

From a total of 42 blood samples, 15 showed hypoxemia (pO₂ < 85 mmHg) and 17 showed an increased oxygen gradient [p (A-a) O₂ > 18 mmHg]. The liver histology revealed increased ductular proliferation after common bile duct ligation, and reconstruction of bile flow promoted decreased ductular proliferation 5 and 6 weeks post-common bile duct ligation. Pulmonary alterations consisted of decreased parenchymal airspace and increased medial wall thickness. Biliary desobstruction promoted transitory improvements 5 weeks after biliary obstruction (increased parenchymal airspace and decreased MWT-p = 0.003 and p = 0.004, respectively) as well as increased endothelin expression levels (p = 0.009).

CONCLUSIONS

The present model showed lung tissue alterations promoted by biliary obstruction. The biliodigestive anastomosis had no clear direct effects on these alterations.

Antifibrotic effects of total or partial application of amniotic membrane in hepatic fibrosis

Liver fibrosis is the final common pathway of chronic liver diseases, having cirrhosis as a possible progression, which has liver transplantation as the only effective treatment. Human amniotic membrane represents a potential strategy as a therapy for liver fibrosis, due to its anti-inflammatory, anti-fibrotic and immunomodulatory properties. The aim of this study was to evaluate amniotic membrane effects as a treatment for hepatic fibrosis induced in rats by bile duct ligation (BDL), verifying alterations between two different forms of amniotic membrane application, around all the lobes of the liver and around only one lobe of the liver. Two weeks after inducing fibrosis, an amniotic membrane fragment was applied to the surface of the liver, covering it either totally or partially. Four weeks later, the animals were euthanized and liver samples were collected. Histopathological and quantitative analyses demonstrated fibrosis severity decrease and an extremely significant reduction in the deposition of collagen in the groups treated with amniotic membrane, particularly when the amniotic membrane was applied in only one liver lobe. It is concluded that the amniotic membrane acted on the repair of liver fibrosis in both modes of application, with the application of the amniotic membrane around only one hepatic lobe being more effective in reducing the severity / extent of fibrosis.

Is maintenance of the ileocecal valve important to the intestinal adaptation mechanisms in a weaning rat model of short bowel?

PURPOSE

To evaluate the role of maintenance of the ileocecal valve (ICV) in intestinal adaptation mechanisms, in a weaning rat experimental model of short bowel.

METHODS

Forty animals were operated on to produce short bowel syndrome. They were divided into five groups: maintenance (MV) or resection of ICV (RV), kill after 4 days (MV4 and RV4) or 21 days (MV21 and RV21), and a control group (21-day-old rats). Body weights, small bowel and colon lengths and diameters, villus heights, crypt depths, lamina propria and muscle layer thickness, as well as the apoptosis index of villi and crypts and expression of pro- and anti-apoptotic genes, were studied.

RESULTS

Preservation of the ICV promoted increased weight gain (p = 0.0001) and intestinal villus height after 21 days; crypt depth was higher in comparison to controls. It was verified a higher expression of Ki-67 in bowel villi and crypts (p = 0.018 and p = 0.015, respectively) in RV4 group and a higher expression in bowel villi of MV4 group animals (p = 0.03). The maintenance of ICV promoted late increased expression of the anti-apoptotic gene Bcl-XL in the colon (p = 0.043, p = 0.002, p = 0.01).

CONCLUSION

The maintenance of the ICV led to positive changes in this model.

Hemodynamic characteristics of biliary cirrhosis in rats

AIM

To elucidate the hemodynamic characteristics of biliary cirrhosis in common bile duct ligated rats.

METHODS

Biliary cirrhosis was induced in rats by common bile duct ligation (CBDL). Rats were divided into a sham group and a CBDL group. At the end of 4 weeks, portal pressure (PP) and mean arterial pressure (MAP) were measured directly via catheters. Liver or spleen coefficient was the ratio of liver weight or spleen weight to body weight. Proliferation of fibrous tissue was evaluated by Masson staining.

RESULTS

At the end of 4 wk, the liver of CBDL rats was yellow in color and enlarged. The surface of some livers was scattered with numerous nodules. Masson staining indicated extensive proliferation of fibrous tissue and pseudolobule. PP of CBDL rats was increased and MAP was decreased compared with sham rats. There was a significant positive correlation between PP and MAP (R² = 0.9096). PP of rats with severe ascites was lower than that of rats with mild or no ascites.

CONCLUSION

After 4 wk of CBDL, liver cirrhosis and portal hyper-tension develop. PP is determined by the degree of ascites and MAP.

Remote Ischemic Preconditioning Is Efficient in Reducing Hepatic Ischemia-Reperfusion Injury in a Growing Rat Model and Does Not Promote Histologic Lesions in Distant Organs

OBJECTIVE

Ischemic preconditioning (IPC) was developed to diminish ischemia-reperfusion injury (IRI). There are two main ways of performing it: direct ischemic-preconditioning (DIP) and remote ischemic-preconditioning (RIP). The objectives of this study were to investigate local and systemic effects of DIP and RIP in liver IRI.

METHODS

Thirty-two weaning rats (50-70 g body weight; 21 days old) were divided into 4 groups: control (C); ischemia followed by reperfusion (IR); DIP followed by ischemia and reperfusion; and RIP followed by ischemia and reperfusion. In the IR group, the vascular pedicles of medial and left lateral liver lobes were clamped for 60 minutes and then unclamped. In the DIP group, a 10-minute cycle of ischemia followed by a 10-minute reperfusion of the same lobes was performed before 60 minutes of ischemia. In the RIP group, three 5-minute cycles of clamping and unclamping of the femoral vessels were performed before liver ischemia. The animals were euthanized 24 hours after the surgical procedures.

RESULTS

The serum levels of liver enzymes were significantly lower in the RIP group compared to the control and IR groups and to the DIP group. The scores of histologic hepatic lesions were significantly lower in RIP animals than those of IR animals (P = .002) and similar to the C group animals. The Bax/BCl-xl relation was lower in the DIP group than that in the RIP group (P = .045) and no differences were observed in histologic analyses of kidney, lung, intestine, and heart.

CONCLUSION

In young animals, the beneficial effects of RIP are more evident than those of DIP.