Host- and disease-specific factors affecting steatosis in chronic hepatitis C

Fatty liver vulnerability to endotoxin-induced damage despite NF-kappaB induction and inhibited caspase 3 activation

Fatty livers are sensitive to lipopolysaccharide (LPS) damage. This study tests the hypothesis that this vulnerability occurs because protective, antiapoptotic mechanisms are not upregulated appropriately. Genetically obese, leptin-deficient ob/ob mice, a model for nonalcoholic fatty liver disease, and their lean litter mates were treated with a small dose of LPS. General measures of liver injury, early (i.e., cytochrome c release) and late (i.e., activation of caspase 3) events that occur during hepatocyte apoptosis, and various aspects of the signal transduction pathways that induce nuclear factor-kappaB (NF-kappaB) and several of its antiapoptotic transcriptional targets (e.g., inducible nitric oxide synthase, bfl-1, and bcl-xL) were compared. Within 0.5-6 h after LPS exposure, cytochrome c begins to accumulate in the cytosol of normal livers, and procaspase 3 cleavage increases. Coincident with these events, kinases (e.g., AKT and Erk-1 and -2) that result in the degradation of inhibitor kappa-B are activated; NF-kappaB activity is induced, and NF-kappaB-regulated gene products accumulate. Throughout this period, there is negligible histological evidence of liver damage, and serum alanine aminotransferase values barely increase over baseline values. Although ob/ob livers have significant histological liver injury and 11-fold greater serum alanine aminotransferase values than those of lean mice by 6 h post-LPS, they exhibit greater activation of AKT and Erk, more profound reductions in inhibitor kappa-B, enhanced activation of NF-kappaB, and greater induction of NF-kappaB-regulated genes. Consistent with this heightened antiapoptotic response, increases in cytochrome c and procaspase 3 cleavage products are inhibited. Together with evidence that ob/ob hepatocytes have a reduced ATP content and undergo increased lysis after in vitro exposure to tumor necrosis factor-alpha, these findings suggest that fatty livers are sensitive to LPS damage because of vulnerability to necrosis, rather than because of apoptosis.

"Hepatitic flare", asthenia, peripheral polyneuropathy and diffuse liver steatosis in a hepatitis C virus asymptomatic chronic carrier

In July 2000, a 62-year-old female, with a ten-year history of chronic hepatitis C virus infection and persistently normal aspartate amino-transferase and alanine aminotransferase levels, presented with asthenia, weight loss, peripheral polyneuropathy and increased levels of aspartate aminotransferase (8 times upper normal limit), alanine aminotransferase (10 times upper normal limit) and gamma glutamyl-transferase (6 times upper normal limit). The ultrasound findings were consistent with massive liver steatosis. The patient had been previously diagnosed elsewhere as having hepatitis C virus-related "hepatitic flare" with neurological involvement related to concomitant mixed type-III cryoglobulinaemia. However intense exposure to trichloroethylene since April 2000 was revealed and liver histology was fully consistent with non-alcoholic steatohepatitis. The pathogenetic role of the solvent was definitely supported by the complete clinical and biochemical remission within six months of trichloroethylene withdrawal.

Hepatitis C virus induced hypobetalipoproteinemia: a possible mechanism for steatosis in chronic hepatitis C

BACKGROUND/AIMS

Steatosis could be the result of HCV (hepatitis C virus)-induced hypobetalipoproteinemia in patients with chronic hepatitis C. The aim of this study was to assess serum levels of main constituents of betalipoproteins and their relationship with steatosis in patients with chronic hepatitis C without known risk factors for steatosis.

PATIENTS

One-hundred male patients with untreated biopsy proven non-cirrhotic chronic hepatitis C were included. Twenty-nine of these patients were further treated with interferon.

RESULTS

Cholesterol concentration was significantly lower in patients compared to three control groups: reference male population, patients with chronic hepatitis B or with non-alcoholic fatty liver. In multivariate analysis, low apolipoprotein B concentration was an independent factor related with the degree of steatosis. Hypobetalipoproteinemia and degree of steatosis were significantly associated with infection with genotype 3. Among treated patients, only sustained virological responders had a significant increase of cholesterol (5.6 +/- 1 vs. 4.7 +/- 1.3 mmol/l; P = 0.03) and apolipoprotein B concentrations (113 +/- 19 vs. 75 +/- 14 mg/dl; P = 0.05).

CONCLUSION

In chronic hepatitis C, hypobetalipoproteinemia is prevalent and associated with steatosis, especially in patients infected with genotype 3. The correction of hypobetalipoproteinemia following HCV eradication suggests that HCV itself could induce hypobetalipoproteinemia and steatosis.

Increase in the concentration of carbon 18 monounsaturated fatty acids in the liver with hepatitis C: analysis in transgenic mice and humans

Steatosis is one of the histologic characteristics of chronic hepatitis C and is well reproduced in a transgenic mouse model for hepatocellular carcinoma (HCC) in which the core protein of hepatitis C virus (HCV) plays a pivotal role in inducing steatosis and HCC. In the present study, the lipid composition in the liver of the HCV core gene transgenic mice as well as in those of chronic hepatitis C patients was determined. The concentration of carbon 18 monounsaturated (C18:1) fatty acids, such as oleic and vaccenic acids, which are known to increase membrane fluidity leading to higher cell division rates, significantly increased in the livers of transgenic mice compared to nontransgenic control mice. The concentration of C18:1 fatty acids also significantly increased in the livers of chronic hepatitis C patients compared to subjects without HCV infection. These results suggest that HCV may affect a specific pathway in the lipid metabolism and cause steatosis in the liver.

Steatosis and chronic hepatitis C: analysis of fibrosis and stellate cell activation

BACKGROUND/AIMS

Steatosis is a frequent histological finding in chronic hepatitis C and is associated with increased hepatic fibrosis.

METHODS

We studied 80 patients with untreated chronic hepatitis C to determine whether steatosis contributes to fibrosis through a steatohepatitis-like pathway.

RESULTS

Fine sinusoidal and/or central vein fibrosis was present in 52 patients (65%). This was typically located in acinar zone 3 and had a chicken-wire appearance similar to that seen in steatohepatitis. A statistically significant relationship was found between subsinusoidal fibrosis and age (r(s) = 0.33, P = 0.003) and grade of steatosis (r(s) = 0.35, P = 0.001). Mean body mass index was higher in patients with focal (28.4 +/- 4.7 kg/m2) or extensive (29.6 +/- 5.9 kg/m2) subsinusoidal fibrosis than in those patients with no subsinusoidal fibrosis (25.5 +/- 3.7 kg/m2). The extent of alpha-smooth muscle actin staining (as a marker of stellate cell activation) correlated with the degree of portal inflammation and the stage of portal fibrosis, but not with the grade of hepatic steatosis.

CONCLUSIONS

These findings suggest that in hepatitis C infection, host factors, particularly adiposity, contribute to both steatosis and acinar fibrosis. The implication of these observations is that weight reduction may provide an important therapeutic strategy for patients with chronic hepatitis C.

Hepatic steatosis in chronic hepatitis C virus infection: prevalence and clinical correlation

BACKGROUND AND AIMS

Hepatic steatosis is a histological characteristic in patients with chronic hepatitis C virus (HCV) infection. The aim of this study was to evaluate the prevalence of hepatic steatosis in Chinese patients with chronic hepatitis C, and to look for possible correlation with various histopathological changes and to look for possible correlation with various clinical and pathologic variables.

METHODS

One hundred and six patients were enrolled, and patients with alcoholism or diabetes mellitus were excluded. Clinical, biochemical and virologic data, including HCV genotype and serum HCV-RNA titer and histological findings, were compared between patients with and without hepatic steatosis.

RESULTS

Fifty-five (52%) of the 106 patients with chronic hepatitis C had hepatic steatosis. Patients with hepatic steatosis had significantly higher mean serum levels of triglyceride and gamma-glutamyl transpeptidase, higher body mass index, and a higher incidence of obesity compared with patients without hepatic steatosis. No significant differences in serum HCV-RNA titer and HCV genotype or the response to interferon therapy were noted between the two groups. Histological analysis showed patients with hepatic steatosis had a significantly higher mean fibrotic score than patients without hepatic steatosis (1.9 +/- 1.2 vs 1.3 +/- 1.0; P = 0.016). There were no significant differences in the severity of necroinflammation, the presence of lymphoid aggregation/follicle or bile duct damage between the two groups. Multivariate logistic regression analysis showed that independent predictors associated with hepatic steatosis were obesity or a histology fibrotic score of > or = 2.

CONCLUSION

It was found that 52% of Chinese patients with chronic hepatitis C had hepatic steatosis. Patients with hepatic steatosis were more frequently obese and had more severe hepatic fibrosis.

Impaired activity of phagocytic cells in Candida albicans infection after exposure to chronic varied stress

OBJECTIVE

Candidiasis is a prototypic opportunistic fungal disease that may follow severe modulations of the immune system of the host. The purpose of this study was to evaluate which innate immune mechanisms involved in the protection against fungal invasion are impaired under stress conditions.

METHODS

Wistar rats were infected intraperitoneally with Candida albicans and immediately exposed to chronic varied stress (CVS) over 10 days (CVS; Ca-S); the fungal burden (CFU), histopathological lesion and ACTH levels were evaluated. Additionally, functional assessment of peritoneal cells (PC) included the phagocytic and anticandidacidal activities and the production of H(2)O(2) and NO.

RESULTS

In the only infected animals (Ca), C. albicans colonization stimulated an efficient inflammatory response, while in Ca-S rats poor tissue reactions were associated with increased CFU in livers and kidneys (p < 0.05, Ca vs. Ca-S). Whereas the phagocytic process was not modified, the candidacidal activity of PC was significantly decreased after the application of CVS (p < 0.001, Ca vs. Ca-S). The H(2)O(2) production by macrophages and neutrophils was downregulated by the infection, and while at early intervals these cells possessed a residual oxidative capacity, by day 10, the production of this metabolite was blocked. Spontaneous NO production by macrophages was significantly increased in both Ca and Ca-S animals (p < 0.001), but in stressed rats, this reactive nitrogen intermediate was noticeably downregulated (p < 0.05, Ca vs. Ca-S). The hyperactivity of hypothalamus-pituitary-adrenal axis after exposure to stress was confirmed by an increase in baseline plasma ACTH levels.

CONCLUSION

These results show that during infection with C. albicans, the exposure to CVS contributes to the spread of the fungus and downregulates critical functions of phagocytic cells involved in the control of this opportunistic pathogen.

Leptin has no role in determining severity of steatosis and fibrosis in patients with chronic hepatitis C

OBJECTIVE

The presence of steatosis is a common histological finding in patients with chronic hepatitis C (CHC). The causes of the severity of this condition are not yet clear, although both metabolic and viral factors supposedly are involved. In this study our aim was to examine the possible influence that leptin levels, hepatitis C virus (HCV) RNA levels, and hepatitis G virus (HGV) infection have on the severity of steatosis and on the presence and degree of fibrosis in patients with CHC.

METHODS

One hundred eighty-two CHC patients with histological findings of steatosis were chosen from among a cohort of patients referred to our center for staging of liver disease. Among them 48 CHC patients were accurately selected so as to rule out possible confounding factors for the presence of steatosis (diabetes mellitus, hyperlipemia, obesity, alcohol). Leptin levels, HCV RNA levels, and HCV genotype, and the presence of HGV RNA were assessed in these patients and related to histological findings.

RESULTS

We found that leptin levels in CHC patients were similar to those in healthy subjects. No relationship was found between leptin levels and severity of steatosis. HCV RNA levels, HCV genotype, and the presence of HGV infection were no different among CHC patients with various degrees of steatosis. Leptin was not related to different degrees of fibrosis, whereas higher viral load was the only parameter associated to higher fibrosis scores.

CONCLUSIONS

These findings suggest that the degree of steatosis in patients with CHC does not seem to depend on serum leptin levels or on viral factors, at least as far as HCV viremia and genotype and HGV infection are concerned. The severity of fibrosis does not seem to be influenced by leptin levels, whereas HCV viral load does seem to play some role.

Human leukocyte antigen DR markers as predictors of progression to liver transplantation in patients with chronic hepatitis C

OBJECTIVE

Because many patients with chronic viral hepatitis do not progress to end-stage liver disease, it is possible that host factors such as human leukocyte antigen (HLA) differences are important. Our aims were to determine HLA marker-specific rates of progression to liver transplantation among patients with chronic hepatitis C; and to determine if polymerase chain reaction (PCR)-based HLA DRB1 typing can be performed on stored serum samples.

METHODS

Forty-two hepatitis C virus RNA-positive liver transplant patients and 87 untransplanted patients were included in a Cox proportional hazards model to test whether the occurrence of certain HLA DRB1 markers were associated with progression to liver transplantation. HLA DRB1 typing was performed on stored serum samples using a PCR method.

RESULTS

There were no differences among the HLA DRB1 markers with regard to the HLA marker-specific rate of progression to transplantation among patients with chronic hepatitis C.

CONCLUSIONS

HLA DRB1 markers do not appear to be associated with progression of disease in chronic viral hepatitis C. It is possible to perform PCR-based HLA DRB1 typing on stored frozen serum samples.

Hepatocyte steatosis is a cytopathic effect of hepatitis C virus genotype 3

BACKGROUND/AIMS

Patients infected with the hepatitis C virus (HCV) often have liver steatosis, suggesting the possibility of a viral cytopathic effect. The aim of this study was to correlate the occurrence and severity of liver steatosis with HCV RNA type, level and sequence of the core-encoding region.

METHODS

We scored the liver steatosis in 101 HCV-infected individuals carefully selected to exclude other risk factors of a fatty liver. Results were compared with HCV RNA genotype and level in serum and liver. In selected patients, we assessed the effect of antiviral therapy on steatosis and the relationship between nucleocapsid sequence heterogeneity and fat infiltration.

RESULTS

Steatosis was found in 41 (40.6%) patients, irrespective of sex, age or route of infection. HCV genotype 3 was associated with higher steatosis scores than other genotypes. A significant correlation between steatosis score and titer of intrahepatic HCV RNA was found in patients infected with genotype 3, but not in those infected with genotype 1. In selected patients, response to alpha-interferon was associated with the disappearance of steatosis. Analysis of the nucleocapsid of 14 HCV isolates failed to identify a sequence specifically associated with the development of steatosis.

CONCLUSIONS

We provide virological and clinical evidence that the steatosis of the liver is the morphological expression of a viral cytopathic effect in patients infected with HCV genotype 3. At variance with published evidence from experimental models, the HCV nucleocapsid protein does not seem to fully explain the lipid accumulation in these patients.

Natural history of HCV infection

Chronic hepatitis C virus (HCV) infection affects 170 million individuals worldwide. These individuals are at risk of developing both hepatological and non-hepatological manifestations. HCV is usually only fatal when it leads to cirrhosis, the final stage of liver fibrosis. Therefore, an estimate of fibrosis progression represents an important surrogate end-point for the evaluation of the vulnerability of an individual patient. In untreated patients, the median expected time to cirrhosis is 30 years; 33% of patients have an expected median time to cirrhosis of less than 20 years and 31% will only progress to cirrhosis after more than 50 years, if ever. Several factors are associated with fibrosis progression rate: duration of infection, age, male gender, consumption of alcohol, HIV co-infection and low CD4 count. Non-hepatological manifestations are frequent with more than 70% of HCV patients experiencing fatigue or at least one extrahepatic clinical manifestation involving primarily the joints, skin and muscles. Several immunological abnormalities are frequently observed, including cryoglobulins (40%),anti-nuclear antibodies (10%) and anti-smooth muscle antibodies (7%). In contrast severe extrahepatic manifestations are rare, with 1% for systemic vasculitis.

Hepatitis C and alcohol

A close relationship and possible interaction has been noted between alcohol intake and hepatitis C virus infection, since the discovery of HCV markers. It is not understood whether these are additive or synergistic effects in causing liver injury. Interactions between alcohol and HCV may be studied at several levels, including epidemiology, virology (including viral load), histology (effect on the severity of liver lesions), carcinogenesis (the role of alcohol in the occurrence of hepatocellular carcinoma), and the effect on the extrahepatic manifestations or severity of HCV infection. At the epidemiological level, a high prevalence of HCV infection was noted in patients with alcoholic liver diseases (14-37%), also characterized by a high rate of viral replication as detected by PCR, which was present in over 90% of patients tested. Moreover, the prevalence of anti-HCV antibodies increased proportionally with the severity of liver lesions. Virological analysis based on the determination of HCV RNA levels in the serum showed variations of HCV RNA levels with diet, and a clear relationship between self reported alcohol consumption and the levels of serum HCV RNA (r = .26, p = .001). At the histologic level the role of alcohol may be evaluated either through the development of fibrosis or by determination of the incidence of cirrhosis. A study on the effect of alcohol intake below or over 40 g per day on the histologic progression of liver lesions has confirmed a more rapid increase in fibrosis and a doubling in the incidence of cirrhosis in patients admitting to alcohol consumption >40 g per day. The role of alcohol in the occurrence of hepatocellular carcinoma in patients with cirrhosis due to HCV infection has been extensively studied with controversial results. A recent case control study performed in Italy showed that the relative risk of HCC in patients with HCV infection and heavy alcohol consumption doubled. Finally, alcohol consumption potentially worsens the evolution of dermatological diseases associated with HCV infection such as porphyria cutanea tarda. All of the above are strong arguments which should be used to advise HCV patients against alcohol consumption, regardless of the degree of liver injury. However, the deleterious effect of the occasional intake of small amounts of alcohol has not been demonstrated and therefore an occasional drink may be allowed in some cases.

Properties of the hepatitis C virus core protein: a structural protein that modulates cellular processes

The core protein of hepatitis C virus (HCV) is believed to form the capsid shell of virus particles. Maturation of the protein is achieved through cleavage by host cell proteases to give a product of 21 000 MW, which is found in tissue culture systems and sera from infected individuals. However, efficient propagation of the virus is not possible at present in tissue culture. Hence, studies have focused on the properties of the core protein and its possible role in pathologies associated with HCV infection. This review describes key features of the polypeptide and the status of current knowledge on its ability to influence several cellular processes.

Pathologic features of chronic hepatitis. A review and update

The general histopathologic changes of chronic hepatitis and those related to the various causes are reviewed. Consideration also is given to underlying or associated diseases and to mixed infections in chronic viral hepatitis. Changes occurring in exacerbations or relapses are described. Selected histopathologic changes are illustrated. The nomenclature is reviewed briefly, with emphasis on separation of activity from stage of disease.

Steatosis and intrahepatic hepatitis C virus in chronic hepatitis

Hepatic steatosis has been reported as one of the characteristics which discriminates hepatitis C from other forms of hepatitis, besides lymphoid follicles and bile duct damage. However, it is unclear whether or not the presence of hepatitis C virus (HCV) itself is associated with the development of steatosis. The possibility that the HCV itself is directly related to the development of steatosis was examined. The intrahepatic core protein levels, as a marker of the HCV load, were correlated with the presence of steatosis in 43 patients with chronic hepatitis C. Among 43 patients studied by Western blotting, the core protein was detected in the liver in 27 (62.8%). On the other hand, hepatic steatosis was observed in 21 (48.8%) of the 43 patients. Importantly, the core protein was detectable in 19 (90.4%) of the 21 patients with steatosis, while it was detected in only 8 (36.4%) of the 22 patients without steatosis (P = 0.008). However, serum HCV-RNA levels as determined by the Amplicor monitor were not significantly different between patients with and without steatosis. Multivariate analysis showed that the serum alanine aminotransferase level (P = 0. 013), body mass index (P = 0.038), and intrahepatic HCV core protein positivity (P = 0.038) were the independent parameters best predictive of steatosis. These results indicate a close relationship between intrahepatic HCV and the development of steatosis, and suggest a possible role of the HCV itself or core protein in the pathogenesis of steatosis in human chronic hepatitis C.

Pathology of the liver

Among the topics of recent investigation in liver pathology were an examination of normal portal tract structures in needle liver biopsies, computer reconstructions of the intrahepatic biliary tree, identification of oval cells (presumed progeny of hepatic stem cells) in a variety of biliary and nonbiliary diseases and tumors, the features and pathogenesis of nonalcoholic steatohepatitis, and further characterization of proliferating bile ductules. A morphometric study of portal structures in normal needle liver biopsies found that approximately one third in a given specimen may not show a portal vein and that a bile duct may not be seen in 7%. Apoptosis is a critical mechanism for the death of hepatocytes in viral hepatitis and also in endothelial injury in the cold perfusion-warm reperfusion sequence in liver transplantation. The results of two studies examining the relationship of steatosis to chronic hepatitis C virus infection in native and transplanted livers suggest that fatty change is a specific virus-mediated lesion. In the field of hepatic neoplasia, liver cell dysplasia (large cell change), long thought to be a premalignant lesion, was hypothesized to represent abnormal hepatocyte polyploidization.

Autoimmune liver disease

The incidence and prevalence of autoimmune hepatitis are greater than expected among white northern Europeans. Patients with type 2 autoimmune hepatitis have different HLA frequencies than patients with type 1 disease and HLA-DRB1*07 may be an important risk factor. Hepatitis C virus can trigger autoimmune hepatitis after needlestick inoculation. Elderly patients have milder disease than young patients and they are frequently untreated. Cryptogenic chronic hepatitis is indistinguishable from autoimmune hepatitis and it responds as well to corticosteroids. Variant syndromes are common and the degree of cholestasis influences the treatment response. Endomysial antibodies indicate celiac sprue in asymptomatic patients, and multiple endocrinopathies in individuals with type 2 disease may reflect molecular mimicries and cross-reacting autoantibodies. Phase I (cytochromes P-450) and phase II (uridine diphosphate glucuronosyltransferases) drug-metabolizing enzymes are the autoantigens of syndromes characterized by liver/kidney microsomal autoantibodies. T-cell vaccination prevents the occurrence of experimental hepatitis in mice and it can also treat the disease. Liver transplantation can be complicated by recurrent disease, frequent allograft rejection, and de novo autoimmune hepatitis.

Fatty liver and nonalcoholic steatohepatitis. Where do we stand and where are we going?

BACKGROUND

Fatty liver (FL) is the most common liver disease but its clinical significance remains elusive. Nonalcoholic steatohepatitis (NASH) is increasingly recognized as a cause of liver failure, sometimes recurring following transplantation. Recent data on both conditions are critically reviewed.

METHODS

A Medline search of the medical literature (1990 to September 1998) and cross-references was performed.

RESULTS

FL most commonly affects middle-aged men with obesity, altered glucose metabolism, hyperlipidemia, and hypertension. The link between biology of HCV, iron metabolism and FL should be addressed. Prospective studies should also quantify the rate and the factors involved in the progression of FL to NASH. The clinical spectrum of NASH is currently broader than it was initially recognized. Diagnosis of FL and NASH may involve ultrasonography, liver biopsy, and recognition of related conditions. Treatment of these conditions must be tailored according to patient's features.

CONCLUSIONS

The clinical significance of FL is incompletely understood at present. The relationship, if any, of FL and the metabolic syndrome should be carefully investigated.