Hepatic stellate cells (Ito cells) but not collagen IV may partly be responsible for lower portal pressure after reversing secondary biliary cirrhosis in the rat

Animal Models for Fibrotic Liver Diseases: What We Have, What We Need, and What Is under Development

Liver fibrosis is part of the wound-healing response to liver damage of various origins and represents a major health problem. Although our understanding of the pathogenesis of liver fibrosis has grown considerably over the last 20 years, effective antifibrotic therapies are still lacking. The use of animal models is crucial for determining mechanisms underlying initiation, progression, and resolution of fibrosis and for developing novel therapies. To date, no animal model can recapitulate all the hepatic and extra-hepatic features of liver disease. In this review, we will discuss the current rodent models of liver injuries. We will then focus on the available ways to target specifically particular compounds of fibrogenesis and on the new models of liver diseases like the humanized liver mouse model.

Influence of biliary anastomosis on recovery from secondary biliary cirrhosis

OBJECTIVE

The influence of choledochoduodenostomy and choledochojejunostomy on the repair of hepatic lesions secondary to biliary obstruction is not well known. The aim of the present study was to compare the effects of choledochoduodenostomy and choledochojejunostomy on the recovery of these lesions in rats with biliary obstruction.

METHODS

Rats subjected to 4 weeks of biliary obstruction underwent choledochoduodenostomy (n=10) or choledochojejunostomy (n=10). The following variables were measured: total bilirubin, alkaline phosphatase, aminotransferases, and albumin. Hepatic mitochondrial energy metabolism was evaluated by calculating the respiratory control ratio and the oxidative phosphorylation index. Hepatic morphometry was used to estimate the mass of the hepatocytes, bile ducts, and fibrosis, as well as the hepatic stellate cell count.

RESULTS

After choledochoduodenostomy and choledochojejunostomy, there was a regression in cholestasis and a reduction in the oxidative phosphorylation index. However, the total bilirubin, alkaline phosphatase, albumin, and respiratory control ratio values improved only after choledochojejunostomy. The mass of the liver, spleen, and fibrosis was reduced after both choledochoduodenostomy and choledochojejunostomy, but the number of hepatic stellate cells increased. After choledochojejunostomy, the hepatic mass recovered completely, and the spleen mass was significantly reduced compared with that after choledochoduodenostomy. After both choledochoduodenostomy and choledochojejunostomy, enterobiliary reflux, biliary contamination, and an exacerbation in hepatic inflammation developed.

CONCLUSION

Choledochojejunostomy was more effective than choledochoduodenostomy, but both techniques induced enterobiliary reflux and biliary contamination, which may explain the maintenance of hepatic alterations, especially after choledochoduodenostomy.

A novel model of CCl4-induced cirrhosis with ascites in the mouse

BACKGROUND/AIMS

The current approaches to study the molecular mechanisms involved in the pathophysiology of liver diseases often rely on the use of transgenic mice. However, experimental models of decompensated cirrhosis have not been clearly established in mice. Thus, we aimed to set an efficient and well-tolerated protocol to induce cirrhosis in mice able to progress up to the ascitic stage.

METHODS

C57BL/6N mice received CCl(4) subcutaneously, intraperitoneally or by inhalation. In the latter group, gaseous CCl(4) was administered according to three different schedules: increasing exposure times, twice weekly (traditional protocol; TP), short inhalation cycles, twice or three times weekly.

RESULTS

Portal hypertension, sodium retention, and ascites developed in all groups between 11 and 15 weeks. Mortality reached 70% in the TP group, but it was only 0-10% with all other protocols. All the inhalation groups had significantly more ascites at sacrifice than those receiving CCl(4) subcutaneously and intraperitoneally. Extensive abdominal adhesions and evidence of enhanced hepatic inflammation, as suggested by the increased gene expression of pro-inflammatory cytokines in liver tissue, were found in the intraperitoneal group, while large granulomas at the injection site and marked neutrophil infiltration of lungs developed in the subcutaneous group. No extra-hepatic damage could be detected in mice inhaling CCl(4).

CONCLUSIONS

The use of short cycles of CCl(4) inhalation represents a novel, safe, and effective method to induce decompensated cirrhosis in mice. Intraperitoneal CCl(4) leads instead to abdominal adhesions precluding a correct evaluation of ascites, while subcutaneous CCl(4) causes an unwanted systemic inflammatory response.

Hepatic stellate cells in hepatitis C patients: relationship with liver iron deposits and severity of liver disease

BACKGROUND AND AIM

To determine the relationship between hepatic stellate cell (HSC) populations and severity of liver disease and liver iron deposits in patients with chronic hepatitis C virus (HCV). We also studied the relationship between iron cellular distribution and HSC population and the role of HFE mutations in the determination of iron deposits.

METHODS

Forty-nine chronic HCV patients with varying degrees of liver damage and liver iron deposits were studied. A liver biopsy was scored for histology activity index (HAI), fibrosis and iron deposits. The number of HSC in the liver was evaluated by an immunohistochemical double-staining method to identify glial fibrillary acid protein (GFAP) and smooth muscle alpha-actin (alpha-SMA).

RESULTS

The HSC population was significantly higher in HCV patients than in normal controls and was predominant in zones 1 and 3. Liver iron deposits were observed in 49% of patients and were mild/moderate in most cases. We found a significantly higher number of GFAP and alpha-SMA positive cells in patients with liver iron deposits compared with those without iron deposits, and a positive correlation between liver iron scores and number (%) of GFAP and alpha-SMA positive cells. We observed a significantly higher number of GFAP and alpha-SMA positive cells in moderate/severe hepatitis than in minimal/mild hepatitis, and a positive correlation between GFAP and alpha-SMA positive cells and HAI and fibrosis scores.

CONCLUSIONS

Liver iron deposits in chronic HCV are common and are associated with activation of HSC. Thus, even mild iron deposits might stimulate HSC and contribute to liver damage.

Liver allograft iron accumulation in patients with and without pretransplantation hepatic hemosiderosis

There is a paucity of data regarding hepatic allograft iron accumulation in patients undergoing orthotopic liver transplantation (OLT) in whom severe iron overload was present in the native explanted liver. Our aim is to evaluate the frequency and cellular distribution of stainable iron in early and late post-OLT hepatic allograft biopsy specimens from patients undergoing their first OLT who had excess iron in their native explanted liver. We compared iron-staining patterns in hepatic allograft biopsy specimens at approximately 1 month (early) and 1 to 2 years (late) post OLT in 41 patients with hepatic iron indices greater than 1.9 in the explanted liver (cases) with a selected group of matched controls without explant hemosiderosis. Our cases included 6 patients with a pre-OLT diagnosis of hereditary hemochromatosis and 35 patients with cirrhosis and secondary iron overload. Early iron deposition was mild in most cases, commonly affected Kupffer's cells, and was seen with similar frequency in cases and controls (41% v 27%; P =.29). Stainable iron was observed in 20 donor livers (12 cases, 8 controls), and all 20 subjects showed stainable iron in 1-month hepatic allograft biopsy specimens. Liver samples from 35 matched pairs were studied for late iron deposition. Iron deposition was observed in 43% of cases versus 17% of controls (P =.06). In conclusion, the frequency of stainable iron in early hepatic allograft biopsy specimens was not different between patients with versus without pre-OLT hepatic hemosiderosis. There was a suggestion that patients with severe pre-OLT hemosiderosis had a greater frequency of iron accumulation in late hepatic biopsy specimens.

Immunocytochemical study on the liver innervation in patients with cirrhosis

In the liver, the autonomic nervous system plays an important role in degenerative and inflammatory changes. The aim of the present study was to investigate the distribution of neuronal fibres containing neuropeptides in livers of 5 patients with cirrhosis by immunocytochemical localization at the light and electron microscopical level of substance P (SP), neuropeptide Y (NPY), somatostatin (SOM), and calcitonin gene-related peptide (CGRP). In patients with alcoholic cirrhosis, a decreased number of neuronal fibres was found in the portal tract and fibrous septa as well as in the sinusoids of regenerative nodules. NPY- and SP-immunoreactive neuronal fibres were more numerous than CGRP-containing fibres. They were located mainly in portal tracts. These findings led to the conclusion that peptidergic innervation plays a role in inflammatory and fibrotic changes in cirrhotic liver.

Cytomegalovirus antigenemia directed pre-emptive prophylaxis with oral versus I.V. ganciclovir for the prevention of cytomegalovirus disease in liver transplant recipients: a randomized, controlled trial

BACKGROUND

The efficacy of pre-emptively administered oral ganciclovir in preventing cytomegalovirus (CMV) disease has not been documented in liver transplant recipients. We sought to compare the efficacy of pre-emptive oral ganciclovir with that of i.v. ganciclovir for the prevention of CMV disease after liver transplantation, and to determine whether withholding prophylaxis in the absence of CMV antigenemia, reliably identified patients in whom no prophylaxis was necessary.

METHODS

Surveillance cultures for CMV pp65 antigenemia were performed in all patients at weeks 2, 4, 6, 8, 12, and 16. Patients with CMV antigenemia were randomized into two study groups. The experimental group received oral ganciclovir for 6 weeks (2 g t.i.d. for 2 weeks, then 1 g t.i.d. for 4 weeks), and the control group received i.v. ganciclovir (5 mg/kg q 12 hr) for 7 days.

RESULTS

Of 72 consecutive liver transplant recipients studied, CMV antigenemia occurred in 31% (22 of 72). Twenty-two patients with asymptomatic antigenemia were randomized to two study groups. CMV disease (viral syndrome) occurred in 9% (1 of 11) of the patients in the i.v. ganciclovir group and in 0% (0 of 11) of the patients in the oral ganciclovir group. None of the study patients developed tissue invasive CMV disease. The median reduction in antigenemia level with oral ganciclovir was 55% at week 1, and 100% at week 2. Overall, 64% of the patients by week 1, 93% by week 2, and 100% by week 4 had antigenemia levels below the baseline after oral ganciclovir. Of 50 patients without CMV antigenemia, none developed CMV disease.

CONCLUSIONS

Pre-emptive prophylaxis based on CMV antigenemia can effectively target the patients for CMV prophylaxis; 69% of the patients never received antiviral prophylaxis and did not develop CMV disease. Antiviral therapy instituted upon detection of antigenemia prevented tissue invasive CMV in both ganciclovir groups. Pre-emptively administered oral ganciclovir was effective as prophylaxis for CMV disease after liver transplantation.

Immunohistochemical detection of collagen type III and IV in relation with transformation of Ito cells in liver sinusoids of patients with reactive biliary hepatitis

Reactive biliary hepatitis is a defined morphological entity, which is a result of chronic diseases of the gall bladder, biliary ducts or pancreas. The aim of the present study was to describe the morphology of reactive biliary hepatitis and its significance for progression of liver fibrosis, and in particular Ito cell (fat storing cell) transformation and occurrence of collagen type III and IV in the liver. Liver tissue from 19 patients with reactive biliary hepatitis was investigated light microscopically and immunohistochemically. Histologically, the liver showed features of mild to severe portal and lobular inflammation. The number of Ito cells increased periportally and pericentrally. Deposition of collagen type III and IV was increased in portal tracts, septa and perisinusoidal spaces, mainly in periportal zones of the lobules. Ultrastructurally, collagen type III immunoreactive fibrillar networks were found to be increased in the space of Disse around transitional cells. Collagen type IV immunoreactive deposits were detected around newly proliferating bile ducts in portal stroma and in the space of Disse. Ito cells were mainly transformed into transitional and myofibroblast-like cells. We discuss here the role of Ito cells and certain cytokines in the process of fibrosis of the liver in the course of reactive biliary hepatitis. It is proposed that bile acid retention in bile ducts during non-specific reactive inflammation or a gut endotoxin may cause transformation of Ito cells and increased collagen type III and IV in this type of hepatitis.

Role of HFE gene mutations in liver diseases other than hereditary hemochromatosis

Heavy iron overload, as occurs in primary and secondary hemochromatosis, may cause fibrosis of parenchymal organs, including the heart, liver, and pancreas, and it is a risk factor for the development of hepatocellular carcinoma. Recent evidence indicates that lesser degrees of hepatic iron deposition are also risk factors for nonhemochromatotic liver disease. For example, several recent studies showed extraordinarily high prevalences (about 60% to 75%) of HFE mutations in patients with porphyria cutanea tarda and significantly increased prevalences of these mutations in patients with nonalcoholic steatohepatitis from Australia and the United States. It is less well established that the prevalence of the HFE mutations is increased in alcoholic liver disease and in chronic viral hepatitis, but in both conditions, patients harboring one of these mutations, especially C282Y, are more likely to have advanced hepatic fibrosis or cirrhosis. Thus, these mutations both incite and exacerbate nonhemochromatotic liver disease. In this review, we summarize current knowledge of these associations and emphasize important unresolved questions that require further study.

Reversibility of hepatic mitochondrial damage in rats with long-term cholestasis

BACKGROUND/AIMS

Long-term bile duct ligation in rats is associated with secondary biliary cirrhosis and metabolic alterations, e.g. mitochondrial dysfunction. We performed the current studies to characterize the reversibility of hepatic mitochondrial dysfunction after reversing biliary obstruction by Roux-en-Y anastomosis.

METHODS

Rats were studied after 4 weeks of bile duct ligation, and after 5 or 14 days of reanastomosis. Control rats were pair-fed to treated rats and all rats were studied after starvation for 24 h. Mitochondria were isolated by differential centrifugation and enzyme activities determined by spectrophotometric methods.

RESULTS

In comparison to controls, plasma beta-hydroxybutyrate concentrations were decreased in bile duct ligated rats (200+/-70 vs. 790+/-200 micromol/l) and remained decreased after relief of biliary obstruction. In contrast, plasma free fatty acids were not different between controls and treated rats. Oxidative metabolism of L-glutamate, succinate and duroquinol was decreased in liver mitochondria from bile duct ligated rats. After relief of biliary obstruction, the metabolism of L-glutamate and duroquinol normalized quickly, whereas succinate metabolism remained impaired. Similar results were obtained for the mitochondrial oxidases in disrupted mitochondria. The activities of complex I, II, III and V of the respiratory chain were reduced in bile duct ligated rats. After relief of biliary obstruction, complex I and III normalized quickly, whereas complex II and V remained impaired. Oxidative metabolism of long-chain fatty acids by isolated liver mitochondria was decreased in bile duct ligated rats and did not recover after relief of biliary obstruction.

CONCLUSIONS

Long-term cholestasis in the rat is associated with a decrease in specific functions of liver mitochondria which recover only partially after Roux-en-Y anastomosis. The persistence of decreased mitochondrial fatty acid metabolism cannot be explained by impaired activity of the respiratory chain, but is more likely due to alterations in mitochondrial beta-oxidation.

Hemochromatosis: new insights in pathogenesis and diagnosis following the discovery of the gene

Hemochromatosis is a common and often underdiagnosed disease. Early diagnosis and treatment results in an excellent long-term prognosis. The development of a diagnostic genetic test has improved the feasibility of the goal of prevention of morbidity and mortality from hemochromatosis.