In situ detection of lipid peroxidation in chronic hepatitis C: correlation with pathological features

Role of free radicals in liver diseases

Reactive oxygen and nitrogen species (ROS and RNS) are produced by metabolism of normal cells. However, in liver diseases, redox is increased thereby damaging the hepatic tissue; the capability of ethanol to increase both ROS/RNS and peroxidation of lipids, DNA, and proteins was demonstrated in a variety of systems, cells, and species, including humans. ROS/RNS can activate hepatic stellate cells, which are characterized by the enhanced production of extracellular matrix and accelerated proliferation. Cross-talk between parenchymal and nonparenchymal cells is one of the most important events in liver injury and fibrogenesis; ROS play an important role in fibrogenesis throughout increasing platelet-derived growth factor. Most hepatocellular carcinomas occur in cirrhotic livers, and the common mechanism for hepatocarcinogenesis is chronic inflammation associated with severe oxidative stress; other risk factors are dietary aflatoxin B(1) consumption, cigarette smoking, and heavy drinking. Ischemia-reperfusion injury affects directly on hepatocyte viability, particularly during transplantation and hepatic surgery; ischemia activates Kupffer cells which are the main source of ROS during the reperfusion period. The toxic action mechanism of paracetamol is focused on metabolic activation of the drug, depletion of glutathione, and covalent binding of the reactive metabolite N-acetyl-p-benzoquinone imine to cellular proteins as the main cause of hepatic cell death; intracellular steps critical for cell death include mitochondrial dysfunction and, importantly, the formation of ROS and peroxynitrite. Infection with hepatitis C is associated with increased levels of ROS/RNS and decreased antioxidant levels. As a consequence, antioxidants have been proposed as an adjunct therapy for various liver diseases.

Effect of liver steatosis on therapeutic response in chronic hepatitis C virus genotype 1 infected patients in hungary

Hepatic steatosis seems a frequent histological alteration seen in chronic hepatitis C virus infected patients. There is still a lot to learn about the exact mechanism of effect of liver steatosis and its influence on the progression of liver diseases. Our study involved 96 chronic hepatitis C genotype 1 infected Hungarian patients who received pegylated interferon and ribavirin treatment for the first time. Degree of steatosis, viral and host factors influencing its development and its effect on the efficiency of antiviral treatment were determined. In 61 (64%) of patients the liver tissue showed varying degree of steatosis, which did not show relationship with level of alcohol consumption (p = 0.5792), diabetes mellitus (p = 0.5925) or body mass index (p = 0.9685) in type 1 chronic hepatitis C patients. Degree of steatosis and virus titer showed strong relationship (OR = 2.1). Significant relationship was also found between degree of hepatic steatosis and stage (p = 0.0119), as well as between therapeutic response to combined pegylated interferon + ribavirin treatment and steatosis (p = 0.0012). Our results demonstrated that steatosis has clinical significance in hepatitis C virus genotype 1 infected patients.

Acrolein, a ubiquitous pollutant and lipid hydroperoxide product, inhibits antiviral activity of interferon-alpha: relevance to hepatitis C

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease and can lead to hepatocellular carcinoma and end-stage liver disease. The current FDA-approved treatment for HCV (pegylated interferon-alpha (IFNalpha) with ribavirin) is effective in only about 50% of patients. Epidemiological evidence suggests that obesity, alcohol, smoking, and environmental pollutants may contribute to resistance to IFNalpha therapy in HCV. Acrolein, a ubiquitous environmental pollutant and major component of cigarette smoke, is also generated endogenously by cellular metabolism and lipid peroxidation. This study examines the effects of acrolein on (i) IFNalpha-mediated signaling and antiviral gene expression in cultured and primary human hepatocytes and (ii) HCV replication in an HCV-replicon system. Our data demonstrate that nontoxic concentrations of acrolein significantly inhibited IFNalpha-induced tyrosine phosphorylation of both cytoplasmic and nuclear STAT1 and STAT2, without altering the total levels. Also, acrolein down-regulated IFNalpha-stimulated gene transcription, resulting in reduced expression of antiviral genes. Importantly, acrolein abolished the IFNalpha-mediated down-regulation of HCV viral expression in the HCV-replicon system. This study defines mechanisms involved in resistance to IFNalpha and identifies the pathogenic role of acrolein, and potentially other environmental pollutants, in suppressing IFNalpha antiviral activity and establishes their adverse impact on HCV therapy.

Intragastrically Applicated CCl4-Thiopental Sodium Enhanced Lipid Peroxidation and Liver Fibrosis (Cirrhosis) in Rat: Malonedialdehyde as a Parameter of Lipid Peroxidation Correlated with Hydroxyproline as a Parameter of Collagen Synthesis (Deposition)

We investigated the pathogenesis of liver tissue damage during the lipid peroxidation and fibrogenesis with the observation of correlations between the parameters of collagen synthesis (and deposition) and lipid peroxidation in liver fibrosis (cirrhosis) rats. Rats were randomly divided into two groups, normal and CCl₄-thiopental sod. intoxicated group. And the one group was treated intragastrically with the mixture of CCl₄-thiopental sod. 3 times per week for 3 weeks. The liver tissue and sera were used for the measurement of hydroxyproline (HYP), malonedialdehyde (MDA) and superoxide dismutase (SOD). Biochemical parameters such as aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), total-bilirubin and blood urea nitrogen (BUN) were measured. Additionally, the expression of collagen α1(III) and β-actin mRNA was observed by RT-PCR. The histological change in liver tissue was also observed by Masson's trichrome and H&E staining. Correlation analysis was carried by Spearman's rho method. All biochemical parameters except total-bilirubin were significantly higher in the CCl₄-thiopental sod. treated group than that of the normal group (p < 0.01). In the CCl₄-thiopental sod. treated group, Hyp as a parameter of collagen synthesis (deposition) and MDA as a metabolite of lipid peroxidation, were significantly elevated by 1.98 and 2.11 times higher than that of the normal group (p> 0.001) respectively. The activity of SOD in the CCl₄-thiopental sod. treated group is decreased significantly by 44.8% (p> 0.001). And collagen α1(III) mRNA was more expressed in the CCl₄-thiopental sod. treated group than that of the normal group. However, the expression of β-actin mRNA is showed similar in both of groups. A good correlation was observed between the content of hyp and MDA concentration (r = 0.70, n = 40) in the two groups. And the correlation between the levels of hyp and SOD (r = -0.71, n = 25) is also reliable. However, no correlation were observed between MDA concentration and SOD (r = -0.40, n = 25) in the two groups. Elevated levels of MDA in CCl₄-thiopental sod. treated rats indicated enhancement of lipid peroxidation, which is accompanied by a decrease in SOD activity. Moreover, we could confirm that the parameters of collagen synthesis (and deposition) is in good correlation with the metabolite of lipid peroxidation (MDA) and the lipid peroxidation antagonizing enzyme (SOD). Hence, we propose that ➀ lipid peroxidation and collagen synthesis (and deposition) could be enhanced by intragastrically application of CCl₄-thiopental sod. during a short terms. And ➁ the intoxication of CCl₄-thiopental sod. could be used for monitoring of lipid peroxidation and collagen synthesis (and depositon) for test of antioxidant and antifibrotic agent.

Hepatitis C is a predictor of acute liver injury among hospitalizations for acetaminophen overdose in the United States: a nationwide analysis

Acute liver injury (ALI) following acetaminophen overdose (AO) occurs in less than 10% of cases, but that risk is increased among alcoholics and those with chronic alcoholic liver disease. We sought to assess whether coexistent hepatitis C virus (HCV) infection potentiated the hepatotoxic effects of acetaminophen. We queried the Nationwide Inpatient Sample (1998-2005), a 20% sample of U.S. hospitals, to identify admissions for AO using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. Outcomes were development of ALI (ICD-9-CM: 570.0, 572.2, 573.3), in-hospital mortality, severe liver failure, and resource utilization. There were 42,781 admissions for AO in the sample, yielding a national estimate of 210,436 AO hospitalizations. HCV prevalence increased from 0.5% to 1.5% between 1998 and 2005 (P < 0.0001). The rate of ALI was 7.2%. After adjusting for confounders and excluding patients with cirrhosis, the risk of ALI increased with HCV (adjusted odds ratio [aOR] 1.80; 95% confidence interval [CI]: 1.30-2.48), nonalcoholic fatty liver disease (aOR 7.43; 95% CI: 3.30-16.7), alcoholic liver disease (aOR 6.46; 95% CI: 4.53-9.21), and malnutrition (aOR 3.84; 95% CI: 2.61-5.65). HCV was associated with greater risk of progression to severe liver failure (aOR 3.55; 95% CI: 1.88-6.70). Crude mortality was higher in patients with HCV compared to those without HCV (2.1% versus 0.9%, P = 0.01); patients with ALI had an overall mortality of 8.6%. Length of stay was longer in patients with HCV (4.0 versus 2.6 days, P < 0.0001). Admissions with coexistent HCV also incurred two-fold higher hospital charges than those that did not ($21,400 versus $11,400, P < 0.0001).

CONCLUSION

Our retrospective analysis suggests that patients with HCV may be at increased risk of ALI following AO. These findings warrant further confirmation in prospective studies.

Glucose-6-phosphate dehydrogenase deficiency enhances enterovirus 71 infection

Variations in the cellular microenvironment affect the host's susceptibility to pathogens. Using glucose-6-phosphate dehydrogenase (G6PD)-deficient fibroblasts as a model, this study demonstrated that the cellular redox status affects infectivity as well as the outcome of enterovirus 71 (EV71) infection. Compared with their normal counterparts, G6PD-deficient cells supported EV71 replication more efficiently and showed greater cytopathic effect and loss of viability. Mechanistically, viral infection led to increased oxidative stress, as indicated by increased dichlorofluorescein fluorescence and a diminished ratio of glutathione (GSH) to its disulfide form (GSSG), with the effect being greater in G6PD-deficient cells. Exogenous expression of active G6PD in the deficient cells, which increased the intracellular GSH : GSSG ratio, suppressed the generation of viral progeny. Consistent with this, treatment with N-acetylcysteine offered resistance to EV71 propagation and a cytoprotective effect on the infected cells. These findings support the notion that G6PD status, and thus redox balance, is an important determinant of enteroviral infection.

Comparison of hepatic oxidative DNA damage in patients with chronic hepatitis B and C

8-Hydroxydeoxyguanosine (8-OHdG) is a promutagenic DNA lesion produced by hydroxyl radicals and is recognized as a useful marker in estimating DNA damage induced by oxidative stress. The aim of this study was to clarify the clinical significance of hepatic 8-OHdG levels in patients with chronic viral hepatitis. Hepatic 8-OHdG accumulation was investigated in patients with chronic hepatitis C (CH-C) (n = 77) and chronic hepatitis B (CH-B) (n = 34) by immunohistochemical staining of liver biopsy samples. 8-OHdG positive hepatocytes were significantly higher in patients with CH-C compared to CH-B (median 55.0 vs 18.8 cells/10(5) mum(2), P < 0.0001). The number of positive hepatocytes significantly increased with the elevation of serum aminotransferase levels, especially in CH-C patients (8-OHdG vs alanine aminotransferase (ALT)/aspartate aminotrasferase (AST) were r = 0.738/0.720 in CH-C and 0.506/0.515 in CH-B). 8-OHdG reactivity was strongly correlated with body and hepatic iron storage markers in CH-C (vs serum ferritin, r = 0.615; vs hepatic total iron score, r = 0.520; vs hepatic hepcidin mRNA levels, r = 0.571), although it was related to serum HBV-DNA titers (r = 0.540) and age of patients (r = -0.559) in CH-B. These results indicate that hepatic oxidative DNA damage is common in chronic viral hepatitis, in particular chronic HCV-infected patients, suggesting a possible link between chronic hepatic inflammation and hepatocarcinogenesis. The strong positive correlation between hepatic DNA damage and iron overload suggests that iron content is one of the most likely mediators of hepatic oxidative stress and iron reduction may be beneficial to reduce the incidence of hepatic cancer in CH-C patients.

The presence of steatosis and elevation of alanine aminotransferase levels are associated with fibrosis progression in chronic hepatitis C with non-response to interferon therapy

BACKGROUND/AIMS

Interferon (IFN) therapy leads to regression of hepatic fibrosis in chronic hepatitis C patients who achieve a sustained virologic response (SVR), while the beneficial effect is limited in those who fail to do so. The aim of the present study was to define factors associated with progression of fibrosis in patients who do not achieve a SVR.

METHODS

Fibrosis staging scores were compared between paired liver biopsies before and after IFN in 97 chronic hepatitis C patients who failed therapy. The mean interval between biopsies was 5.9 years. Factors associated with progression of fibrosis were analyzed.

RESULTS

Fibrosis progressed in 23%, remained unchanged in 47% and regressed in 29%. Steatosis and a high average alanine aminotransferase (ALT) between biopsies were independent factors for progression of fibrosis with risk ratios of 5.53 and 4.48, respectively. Incidence and yearly rate of progression of fibrosis was 64% and 0.22+/-0.29 fibrosis units per year in those with both risk factors compared to 8% and -0.04+/-0.17 fibrosis units per year in those negative for both factors.

CONCLUSIONS

Hepatic steatosis and elevated ALT levels are risk factors for progression of fibrosis in chronic hepatitis C patients who fail to achieve a SVR to IFN therapy and therefore may be therapeutic targets to halt the potentially progressive disease.

Serum and Ascitic Fluid Superoxide Dismutase and Malondialdehyde Levels in Patients with Cirrhosis

Summary

Serum and ascitic fluid superoxide dismutase (SOD) and malondialdehyde (MDA) levels were measured in 43 patients with cirrhosis and in a 10 healthy control group.

Compensated cirrhotic patients had no clinically detectable ascites, but decompensated patients had massive ascites. Cirrhotic patients were divided into three groups: patients with compensated cirrhosis (n = 16), patients with decompensated cirrhosis with Spontaneous bacterial peritonitis (SBP) (n = 14), and patients with decompensated cirrhosis without SBP (n = 13).

All cirrhotic patients in the experimental group had significantly higher serum SOD (p < 0.001) and MDA levels (p < 0.01) than those in the control group. There were no significant differences with respect to serum SOD and MDA levels among the three different groups of patients. There was no remarkable difference in ascitic fluid SOD and MDA levels between decompensated cirrhotic patients with and without SBP (p > 0.05).

These results suggest that the increase in serum SOD and MDA levels are not related to the presence of SBP and the status of liver cirrhosis. To sum up, clarifying the impact of increased serum SOD and MDA levels in cirrhotic patients needs further investigation.

Interplay between oxidative stress and hepatic steatosis in the progression of chronic hepatitis C

BACKGROUND/AIMS

The contribution of oxidative stress to the pathogenesis of chronic hepatitis C (CHC) is still poorly elucidated. This study investigated the relationship between oxidative stress, insulin resistance, steatosis and fibrosis in CHC.

METHODS

IgG against malondialdehyde-albumin adducts and HOMA-IR were measured as markers of oxidative stress and insulin resistance, respectively, in 107 consecutive CHC patients.

RESULTS

Oxidative stress was present in 61% of the patients, irrespective of age, gender, viral load, BMI, aminotransferase level, histology activity index (HAI) and HCV genotype. Insulin resistance and steatosis were evident in 80% and 70% of the patients, respectively. In the patients infected by HCV genotype non-3, but not in those with genotype 3 infection HOMA-IR (p<0.03), steatosis (p=0.02) and fibrosis (p<0.05) were higher in the subjects with oxidative stress than in those without. Multiple regression analysis revealed that, HOMA-IR (p<0.01), fibrosis (p<0.01) and oxidative stress (p<0.05) were independently associated with steatosis, whereas steatosis was independently associated with oxidative stress (p<0.03) and HOMA-IR (p<0.02). Steatosis (p<0.02) and HAI (p=0.007) were also independent predictors of fibrosis.

CONCLUSIONS

In patients infected by HCV genotype non-3, oxidative stress and insulin resistance contribute to steatosis, which in turn exacerbates both insulin resistance and oxidative stress and accelerates the progression of fibrosis.

Clastogenic factors in the plasma of patients with hepatitis C: their possible role at the origin of hepatocarcinoma

Clastogenic factors (CF) are endogenous clastogens composed of lipid peroxidation products, cytokines, and abnormal nucleotides of inosine. They are regularly observed after radiation exposure and in chronic inflammatory diseases, where they are supposed to be risk factors for carcinogenesis. In the present study, we evaluate clastogenic activity in the plasma of patients with chronic hepatitis C, HCV-positive liver cirrhosis, and hepatocarcinoma in comparison to liver metastasis. Plasma ultrafiltrates from patients were added to blood cultures of healthy donors (CF test). The chromosomal aberration rates observed in 100 metaphases after 48 hours of cultivation were expressed as adjusted clastogenic scores (ACS). The differences in ACS between the four patient groups and controls were highly significant and represented a 10-fold increase in chromatid-type aberrations. The ACS of patients with cirrhosis and hepatocarcinoma were higher than those of hepatitis patients without these complications, but the differences did not reach statistical significance. Because of cytotoxic effects, the cultures did not grow for 10/17 patients with hepatocarcinoma and were repeated with a reduced volume of ultrafiltrate (0.1 instead of 0.25 mL). The ACS were highest in these 10 patients. When the CF activity of HCV-positive hepatocarcinoma was compared to metastasis because of other malignancies, the differences in ACS were highly significant for the cultures set up with the reduced quantity of ultrafiltrate. The percentage of CF-positive samples was 100% for hepatocarcinoma and 9% for metastasis. The results show that the chromosome-damaging effects of CF increase as the disease progresses to cirrhosis and liver cancer. Formed via the intermediacy of superoxide and generating more superoxide, CF are responsible for an autosustained, long-lived DNA-damaging process, which is documented at the chromosomal level by our technique.

Clastogenic factors as potential biomarkers of increased superoxide production

The formation of clastogenic factors (CF) and their damaging effects are mediated by superoxide, since superoxide dismutase is regularly protective. CF are produced via superoxide and stimulate the production of superoxide by monocytes and neutrophils. This results in a selfsustaining and longlasting process of clastogenesis, which may exceed the DNA repair system and ultimately lead to cancer (Emerit, 1994). An increased cancer risk is indeed observed in conditions accompanied by CF formation. These include irradiated persons, patients with chronic inflammatory diseases, HIV-infected persons and the chromosomal breakage syndromes ataxia telangiectasia, Bloom's syndrome and Fanconi's anemia. Biochemical analysis has identified lipid peroxidation products, arachidonic acid metabolites, nucleotides of inosine and cytokines, in particular tumor necrosis factor alpha, as the clastogenic and also superoxide stimulating components of CF. Due to their chromosome damaging effects, these oxidants can be detected with classical cytogenetic techniques. Their synergistic action renders the CF-test particularly sensitive for the detection of a pro-oxidant state. Correlations were observed between CF and other biomarkers of oxidative stress such as decreases in total plasma thiols or increases in TBARS or chemiluminescence. Correlations between CF and disease activity, between CF and radiation exposure, suggest the study of CF for monitoring these conditions. CF may also be useful as biochemical markers and intermediate endpoints for the evaluation of promising antioxidant drugs.CF formation represents a link between chronic inflammation and carcinogenesis. Prophylactic use of superoxide scavengers as anticarcinogens is therefore suggested.

Iron chelation beyond transfusion iron overload

The effects of systemic iron overload in hereditary (e.g., classic HFE hemochromatosis) or acquired disorders (e.g., transfusion-dependent iron overload) are well known. Several other iron overload diseases, with an observed mild-to-moderate increase in iron in selected organs (e.g., the liver or the brain), or with "misdistribution" of iron within cells (e.g., reticuloendothelial cells) or subcellular organelles (e.g., mitochondria), have been recognized more recently. The deleterious impact of any excess iron may be high as active redox iron may directly contribute to cell damage or affect signaling pathways involved in cell necrosis-apoptosis or organ fibrosis and cancer. This article discusses the potential use of iron chelation therapy to treat iron overload from causes other than transfusion overload.

4-Hydroxynonenal-protein adducts: A reliable biomarker of lipid oxidation in liver diseases

The aldehyde 4-hydroxynonenal (HNE) is a major end-product of peroxidation of membrane n-6-polyunsaturated fatty acids. Primary reactants for HNE are the amino acids cysteine, histidine and lysine, and quantitatively, proteins and peptides represent the most important group of HNE-targeted biomolecules. HNE-protein adducts actually elude the metabolism of the aldehyde, particularly active in the liver, so that they can be easily detected in the hepatic tissue itself and in peripheral blood, and quantified by using immunoassays. Since consistently detectable in various liver disease processes and well related to the intensity of necro-inflammation, HNE-protein adducts may be considered a particularly good marker of lipid oxidation during liver injury. In addition, the demonstrated adduction reaction of HNE with important signalling proteins strongly suggests a pathogenetic role for this lipid aldehyde in the progression of liver diseases.

Clinicopathological significance of antinuclear antibodies in non-alcoholic steatohepatitis

AIM

Serum antinuclear antibodies (ANA) are occasionally noted in patients with non-alcoholic steatohepatitis (NASH). We examined the significance of ANA in NASH.

METHODS

We compared clinicopathological features in patients with ANA-positive NASH (n = 35) and ANA-negative NASH (n = 36). Inflammatory cell profiles and the distribution of oxidative stress markers were also examined immunohistochemically.

RESULTS

ANA-positive NASH was significantly associated with female gender (P = 0.005), high degree of portal inflammation (P = 0.039), interface activity (P = 0.036) and hepatocellular ballooning (P = 0.0008). In addition, ANA of high titer (320-fold or more) was significantly associated with the histological grade and stage of NASH (P = 0.02). The degree of steatosis wais rather mild in the high-titer ANA group(P = 0.01). The analysis of inflammatory cell profiles revealed that CD3-positive T cells were predominant and plasma cells were rather few in the portal area and hepatic lobules in both ANA-positive and ANA-negative groups. There was no difference in the distribution of oxidative stress markers between ANA-positive and ANA-negative groups.

CONCLUSION

These findings suggest that the presence of ANA may be related to the progression of NASH and that a different type of autoimmune mechanism may be involved in the pathogenesis of NASH with ANA, compared to the pathogenesis of autoimmune hepatitis.

Redox regulation of hepatitis C in nonalcoholic and alcoholic liver

Hepatitis C virus (HCV) is an RNA virus of the Flaviviridae family that is estimated to have infected 170 million people worldwide. HCV can cause serious liver disease in humans, such as cirrhosis, steatosis, and hepatocellular carcinoma. HCV induces a state of oxidative/nitrosative stress in patients through multiple mechanisms, and this redox perturbation has been recognized as a key player in HCV-induced pathogenesis. Studies have shown that alcohol synergizes with HCV in the pathogenesis of liver disease, and part of these effects may be mediated by reactive species that are generated during hepatic metabolism of alcohol. Furthermore, reactive species and alcohol may influence HCV replication and the outcome of interferon therapy. Alcohol consumption has also been associated with increased sequence heterogeneity of the HCV RNA sequences, suggesting multiple modes of interaction between alcohol and HCV. This review summarizes the current understanding of oxidative and nitrosative stress during HCV infection and possible combined effects of HCV, alcohol, and reactive species in the pathogenesis of liver disease.

Effect of thymoquinone and Nigella sativa seeds oil on lipid peroxidation level during global cerebral ischemia-reperfusion injury in rat hippocampus

It has been previously reported that Nigella sativa oil (NSO) and thymoquinone (TQ), active constituent of N. sativa seeds oil, may prevent oxidative injury in various models. Therefore, we considered the possible effect of TQ and NSO on lipid peroxidation level following cerebral ischemia-reperfusion injury (IRI) in rat hippocampus. Male NMRI rats were divided into nine groups, namely, sham, control, ischemia and ischemia treated with NSO or TQ. TQ (2.5, 5 and 10 mg/kg), NSO (0.048, 0.192 and 0.384 mg/kg), phenytoin (50 mg/kg, as positive control) and saline (10 ml/kg, as negative control) were injected intraperitoneally immediately after reperfusion and the administration was continued every 24h for 72 h after induction of ischemia. The transient global cerebral ischemia was induced using four-vessel-occlusion method for 20 min. Lipid peroxidation level in hippocampus portion was measured as malondialdehyde (MDA) based on its reaction with thiobarbituric acid (TBA) following ischemic insult. The transient global cerebral ischemia induced a significant increase in TBA reactive substances (TBARS) level (p<0.001), in comparison with sham-operated animal. Pretreatment with TQ and NSO were resulted a significant decrease in MDA level as compared with ischemic group (66.9+/-1.5 vs. 297+/-2.5 nmol/g tissue for TQ, 10 mg/kg; p<0.001 and 153.5+/-1.3 nmol/g tissue for NSO, 0.384 mg/kg; p<0.001). Using a reversed-phase HPLC system, the amount of TQ in NSO was also quantified and was 0.58% w/w. These results suggest that TQ and NSO may have protective effects on lipid peroxidation process during IRI in rat hippocampus.

Efficacy of zinc administration in patients with hepatitis C virus-related chronic liver disease

OBJECTIVE

Zinc supplementation has been shown to contribute to inhibition of liver fibrosis and improvement in hepatic encephalopathy. However, little is known about the anti-inflammatory effect of zinc on hepatitis C virus (HCV)-related chronic liver disease (CLD). We therefore examined the effects of zinc administration on inflammatory activity and fibrosis in the liver of patients with HCV-related CLD.

MATERIAL AND METHODS

Polaprezinc, a complex of zinc and l-carnosine, was administrated at 225 mg/day for 6 months to 14 patients with HCV-related CLD, in addition to their ongoing prescriptions. Peripheral blood cell counts, liver-related biochemical parameters, serological markers for liver fibrosis, HCV-RNA loads, and serum levels of zinc and ferritin were evaluated before and after zinc administration.

RESULTS

Serum zinc concentrations were positively correlated with hepatic reserve before zinc supplementation. A significant increase in serum zinc level was observed after zinc supplementation (64+/-15 versus 78+/-26 mg/dl, p=0.0156). Treatment with polaprezinc significantly decreased serum aminotransferase levels (aspartate aminotransferase (AST): 92+/-33 versus 63+/-23 IU/l, p=0.0004; alanine aminotransferase (ALT): 106+/-43 versus 65+/-32 IU/l, p=0.0002), whereas alkaline phosphatase levels were significantly increased (305+/-117 versus 337+/-118 U/l, p=0.0020). Serum ferritin levels were significantly decreased by treatment with polaprezinc (158+/-141 versus 101+/-80 ng/ml, p=0.0117). The reduction rate of ALT levels by polaprezinc was positively correlated with that of ferritin (r(2)=0.536, p=0.0389). There was a tendency toward a decrease in serum type IV collagen 7S levels after treatment with polaprezinc. However, administration of polaprezinc did not affect peripheral blood cell counts, other liver function tests, or HCV-RNA loads.

CONCLUSIONS

These findings suggest that polaprezinc exerts an anti-inflammatory effect on the liver in patients with HCV-related CLD by reducing iron overload.

Hepatitis C core protein inhibits induction of heme oxygenase-1 and sensitizes hepatocytes to cytotoxicity

Hepatitis C virus (HCV) core protein is a transcriptional modifier whose expression is associated with increased levels of prooxidants in hepatocytes in vivo and in vitro. We previously reported that HCV-infected liver biopsies and core protein-expressing hepatocytes show diminished levels of heme oxygenase-1 (HO-1), which is an important oxidative defense enzyme. The objective of these studies was to test the hypothesis that the expression of core protein sensitizes hepatocytes to toxic injury and inhibits the induction of HO-1 in response to stress. The effects of core protein were tested in two different human hepatocyte cell lines, HepG2 and Huh7, which show increased prooxidative activity and cytotoxicity after treatment with heme, heavy metals, and peroxides compared to control cells. HO-1 is upregulated in response to these treatments in control cells, while the induction is attenuated in core protein-expressing cells. The effects of core protein on HO-1 expression are not accounted for by differences in HO-1 mRNA turnover or by the known effects of core protein on cellular proliferation. Collectively, these data suggest that HCV core protein may contribute to hepatocellular injury by increasing both steady-state levels of prooxidants and the susceptibility of hepatocytes to damage by impairing their response to other sources of oxidative stress.

Stronger Neo-Minophagen C, a glycyrrhizin-containing preparation, protects liver against carbon tetrachloride-induced oxidative stress in transgenic mice expressing the hepatitis C virus polyprotein

BACKGROUND/AIM

Stronger Neo-Minophagen C (SNMC), a glycyrrhizin-containing preparation, has been used as a treatment for chronic hepatitis for more than 30 years in Japan, and shown to be effective in preventing the development of hepatocellular carcinoma in chronic hepatitis C patients, but its underlying mechanisms remain elusive. The aim of this study was to investigate if SNMC had an anti-oxidative effect, as oxidative stress has been proposed to be one of the mechanisms of liver injury in hepatitis C virus (HCV)-associated chronic liver diseases.

METHODS

The protective effect of SNMC against carbon tetrachloride (CCl4)-induced liver injury was examined using transgenic mice expressing the HCV polyprotein.

RESULTS

A small dose of CCl4 (10 microl/kg of body weight) significantly increased the serum alanine aminotransferase (ALT) level and hepatic malondialdehyde content, decreased hepatic reduced glutathione (GSH) content and induced ultrastructural alterations of hepatic mitochondria in transgenic mice, but not in nontransgenic mice. A single SNMC treatment equivalent to a clinical dose significantly restored the serum ALT level and hepatic malondialdehyde and GSH contents, attenuated the ultrastructural alterations of hepatic mitochondria, and increased mRNA expression of gamma-glutamylcysteine synthetase (gamma-GCS).

CONCLUSIONS

Transgenic mice expressing the HCV polyprotein are abnormally vulnerable to oxidative stress. SNMC protects hepatocytes against CCl4-induced oxidative stress and mitochondrial injury in the presence of HCV proteins by restoring depleted cellular GSH.

Correlation of hepatic steatosis with body mass index, serum ferritin level and hepatic fibrosis in Japanese patients with chronic hepatitis C

AIMS

The present study was aimed at determining the predictors of hepatic steatosis and fibrosis in Japanese patients with chronic hepatitis C.

METHODS

The relationship between the degrees of hepatic steatosis or fibrosis and several clinical parameters was evaluated using univariate and multivariate analyses.

RESULTS

Steatosis was observed in 117 out of 184 patients (64%), including 45 patients (25%) with grade 1 (<10% of hepatocytes affected), 56 patients (30%) with grade 2 (10-30%), 12 patients (7%) with grade 3 (30-50%), and four patients (2%) with grade 4 (>50%). In the multivariate analysis, body mass index (BMI) (P = 0.0038) and serum ferritin (P < 0.0001) were selected as independent predictors of hepatic steatosis. Six of the 184 patients (3%) had stage 0 fibrosis (no fibrosis), 87 patients (47%) had stage 1, 55 patients (30%) had stage 2 and 36 patients (20%) had stage 3. In the multivariate analysis, platelet count (P = 0.0012), aspartate aminotransferase (AST) (P = 0.0219), hyaluronic acid (P < 0.0001) and the grade of steatosis (P = 0.0008) were selected as independent predictors of hepatic fibrosis.

CONCLUSION

Obesity and iron storage, as evaluated by BMI and serum ferritin level, respectively, have important roles in the pathogenesis of hepatic steatosis, which is a factor responsible for the development of hepatic fibrosis in Japanese patients with chronic hepatitis C.

4-Hydroxy-2-nonenal adduction of extracellular signal-regulated kinase (Erk) and the inhibition of hepatocyte Erk-Est-like protein-1-activating protein-1 signal transduction

4-Hydroxy-2-nonenal (4-HNE) is a major lipid peroxidation (LPO) product formed during oxidative stress. 4-HNE is highly reactive toward cellular nucleophiles and is implicated in the evolution of numerous pathologies associated with oxidative stress and LPO. Recent evidence suggests that chronic prooxidant exposure results in the loss of extracellular signal-regulated kinase (Erk)-1/2 phosphorylation in vivo, a signaling pathway associated with cellular proliferation, survival, and homeostasis. Immunodetection and molecular analysis were used in this study to evaluate the hypothesis that 4-HNE modification of Erk-1/2 inhibits constitutive Erk-Est-like protein (Elk)-1-activating protein (AP)-1 signaling. Primary rat hepatocytes treated with subcytotoxic, pathologically relevant concentrations of 4-HNE demonstrated a concentration-dependent loss of constitutive Erk-1/2 phosphorylation, activity, and nuclear localization. These findings were consistent with iron-induced intracellular LPO, which also resulted in a concentration-dependent decrease in hepatocyte Erk-1/2 phosphorylation and activity. 4-HNE and iron-induced inhibition of Erk-1/2 was inversely correlated with the accumulation of 4-HNE-Erk-1/2 monomer adducts. 4-HNE treatment of hepatocytes decreased nuclear total and phosphorylated Erk-1/2, Elk-1, and AP-1 phosphorylation as well as cFos and cJun activities. The cytosolic modification of unphosphorylated Erk-1/2 was evaluated in vitro using molar ratios of inactive Erk-2 to 4-HNE consistent with increasing oxidative stress in vivo. Liquid chromatography combined with tandem mass spectrometry confirmed monomer adduct formation and identified the major adduct species at the histidine 178 residue within the kinase phosphorylation lip. These novel results show that the formation of 4-HNE-Erk-1/2 monomer-adducts results in the inhibition of Erk-Elk-AP-1 signaling in hepatocytes and implicates the His 178 residue with the mechanism of inhibition.

Viusid, a nutritional supplement, in combination with interferon alpha-2b and ribavirin in patients with chronic hepatitis C

BACKGROUND

The pathogenesis of chronic hepatitis C (CHC) is associated to severe oxidative stress that leads to necro-inflammation and progression of fibrosis. Previous trials suggested that antioxidative therapy may have a beneficial effect. We evaluated the efficacy and safety of Viusid in combination with interferon alpha-2b (IFN alpha-2b) and ribavirin in patients with CHC.

METHODS

We randomly assigned 100 patients, between October 2002 and December 2004, in two arms: IFN alpha-2b (5 MU on alternate days), ribavirin at a dose of 13 mg/kg daily and Viusid (three sachets daily) vs. IFN alpha-2b (5 MU on alternate days) and ribavirin at a dose of 13 mg/kg daily. Subjects were treated for 48 weeks and then followed for an additional 24 weeks. The primary end point was the histologic response (reduction of at least two points without fibrosis worsening in the total score on the Histological Activity Index).

RESULTS

A significantly high proportion of patients who received combined therapy plus Viusid had a histologic response better than those patients who received IFN alpha-2b and ribavirin (57% vs. 37%, P=0.03). The patients with virologic response achieved the highest percentages of histologic response, irrespective of assigned treatment. Among non-responders, the highest reduction in the mean change from baseline score for necro-inflammatory activity (NA) and fibrosis (F) was reported in patients treated with Viusid [NA, -1.50 (Viusid), -1.20 (without Viusid); F, -0.31 (Viusid), 0.00 (without Viusid)]. Sustained normalization of serum alanine aminotransferase concentration was highest in the Viusid group compared with standard therapy (67% vs. 41%, P=0.009). The overall safety profile was similar in both groups, but interestingly, the anemia was less intense in the group with Viusid (P=0.04).

CONCLUSIONS

Our results suggest that triple therapy with Viusid, IFN alpha-2b and ribavirin was well tolerated and may have a beneficial effect on histologic and biochemical variables. The intensity of anemia is reduced in patients treated with Viusid.

Hepatic oxidative DNA damage correlates with iron overload in chronic hepatitis C patients

Hepatic oxidative stress occurs in chronic hepatitis C (CH-C), but little is known about its producing mechanisms and precise role in the pathogenesis of the disease. To determine the relevance of hepatic oxidatively generated DNA damage in CH-C, 8-hydroxy-2'-deoxyguanosine (8-OHdG) adducts were quantified in liver biopsy specimens by immunohistochemical staining, and its relationship with clinical, biochemical, and histological parameters, and treatment response was assessed in 40 CH-C patients. Hepatic 8-OHdG counts were significantly correlated with serum transaminase levels (r=0.560, p=0.0005) and histological grading activity (p=0.0013). Remarkably, 8-OHdG levels were also significantly related to body and hepatic iron storage markers (vs serum ferritin, r=0.565, p=0.0004; vs hepatic total iron score, r=0.403, p=0.0119; vs hepatic hepcidin messenger RNA, r=0.516, p=0.0013). Baseline hepatic oxidative stress was more prominent in nonsustained virological responder (non-SVR) than in SVR to interferon (IFN)/ribavirin treatment (50.8 vs 32.7 cells/10(5) microm2, p=0.0086). After phlebotomy, hepatic 8-OHdG levels were significantly reduced from 53.4 to 21.1 cells/10(5) microm2 (p=0.0125) with concomitant reductions of serum transaminase and iron-related markers in CH-C patients. In conclusion, this study showed that hepatic oxidatively generated DNA damage frequently occurs and is strongly associated with increased iron deposition and hepatic inflammation in CH-C patients, suggesting that iron overload is an important mediator of hepatic oxidative stress and disease progression in chronic HCV infection.

Ethanol-induced modulation of hepatocellular extracellular signal-regulated kinase-1/2 activity via 4-hydroxynonenal

Modulation of the extracellular signal-regulated kinases (ERK-1/2), a signaling pathway directly associated with cell proliferation, survival, and homeostasis, has been implicated in several pathologies, including alcoholic liver disease. However, the underlying mechanism of ethanol-induced ERK-1/2 modulation remains unknown. This investigation explored the effects of ethanol-associated oxidative stress on constitutive hepatic ERK-1/2 activity and assessed the contribution of the lipid peroxidation product 4-hydroxynonenal (4-HNE) to the observations made in vivo. Constitutive ERK-1/2 phosphorylation was suppressed in hepatocytes isolated from rats chronically consuming ethanol for 45 days. This observation was associated with an increase in 4-HNE-ERK monomer adduct concentration and a hepatic cellular and lobular redistribution of ERK-1/2 that correlated with 4-HNE-protein adduct accumulation. Chronic ethanol consumption was also associated with a decrease in hepatocyte nuclear ELK-1 phosphorylation, independent of changes in total nuclear ELK-1 protein. Primary hepatocytes treated with concentrations of 4-HNE consistent with those occurring during oxidative stress displayed a concentration-dependent decrease in constitutive ERK-1/2 phosphorylation, activity, and nuclear localization that negatively correlated with 4-HNE-ERK-1/2 monomer adduct accumulation. These data paralleled the decreased phosphorylation of the downstream kinase ELK-1. Molar ratios of purified ERK-2 to 4-HNE consistent with pathologic ratios found in vivo resulted in protein monomer-adduct formation across a range of concentrations. Collectively, these data demonstrate a novel association between ethanol-induced lipid peroxidation and the inhibition of constitutive ERK-1/2, and suggest an inhibitory mechanism mediated by the lipid peroxidation product 4-hydroxynonenal.

Vitamin E in chronic liver diseases and liver fibrosis

Liver fibrosis may be considered as a dynamic and integrated cellular response to chronic liver injury. The activation of hepatic stellate cells and the consequent deposition of large amounts of extracellular matrix play a major role in the fibrogenic process, but it has been shown that other cellular components of the liver are also involved. Although the pathogenesis of liver damage usually depends on the underlying disease, oxidative damage of biologically relevant molecules might represent a common link between different forms of chronic liver injury and hepatic fibrosis. In fact, oxidative stress-related molecules may act as mediators able to modulate all the events involved in the progression of liver fibrosis. In addition, chronic liver diseases are often associated with decreased antioxidant defenses. Although vitamin E levels have been shown to be decreased in chronic liver diseases of different etiology, the role of vitamin E supplementation in these clinical conditions is still controversial. In fact, the increased serum levels of alpha-tocopherol following vitamin E supplementation not always result in a protective effect on liver damage. In addition, clinical trials have usually been performed in small cohorts of patients, thus making definitive conclusions impossible. At present, treatment with vitamin E or other antioxidant compounds could be proposed for nonalcoholic fatty liver disease (NAFLD), the most frequent hepatic lesion in western countries which can progress to nonalcoholic steatohepatitis and cirrhosis due to the production of large amounts of oxidative stress products. However, although some studies have shown encouraging results, multicentric and long-term clinical trials are needed.

Increased lipid peroxidation in patients with non-alcoholic fatty liver disease and chronic hepatitis C as measured by the plasma level of 8-isoprostane

BACKGROUND

Oxidative stress plays an important role in the pathogenesis of chronic liver diseases. The plasma level of 8-isoprostane, a product of lipid peroxidation, is a marker of oxidative stress in vivo. The aim of the present study was to clarify whether the degree of lipid peroxidation, as measured by the plasma level of 8-isoprostane, influences the progression of chronic liver diseases and hepatocarcinogenesis.

METHODS

Plasma 8-isoprostane levels were investigated in 14 patients with non-alcoholic fatty liver disease (NAFLD), 75 with chronic hepatitis C (CH-C), 14 with cured CH-C, 14 with HCV-positive hepatocellular carcinoma (HCC-C) and 38 healthy volunteers. 8-Isoprostane was measured by enzyme immunoassay after affinity column purification.

RESULTS

Plasma 8-isoprostane was significantly elevated in NAFLD (11.9 [3.8-56.8] pg/mL), CH-C (10.1 [4.2-134.5] pg/mL) as compared to controls (6.3 [3.6-11.1] pg/mL). Plasma 8-isoprostane values were positively correlated with body mass index in NAFLD (P < 0.05) and with total cholesterol in cured CH-C (P < 0.01). 8-Isoprostane levels were not significantly related to sex, age, biochemical data or iron metabolism markers in all liver diseases. In addition, after the administration of peg-interferon, the values of 8-isoprostane improved in almost all patients, reaching values of healthy subjects.

CONCLUSIONS

8-Isoprostane values are elevated in patients with NAFLD and CH-C as compared to healthy controls. Oxidative stress caused by increased lipid peroxidation is involved in the pathogenesis of NAFLD and CH-C.

Cap-dependent and hepatitis C virus internal ribosome entry site-mediated translation are modulated by phosphorylation of eIF2alpha under oxidative stress

Chronic hepatitis C is often associated with oxidative stress. Hepatitis C virus (HCV) utilizes an internal ribosome entry site (IRES) element for translation, in contrast to cap-dependent translation of the majority of cellular proteins. To understand how virus translation is modulated under oxidative stress, HCV IRES-mediated translation was compared with cap-dependent translation using a bicistronic reporter construct and hydrogen peroxide (H2O2) as a stress inducer. In H2O2-sensitive HeLa cells, H2O2 repressed translation in a time- and dose-dependent manner, concomitant with the kinetics of eIF2alpha phosphorylation. A phosphomimetic of eIF2alpha, which mimics the structure of the phosphorylated eIF2alpha, was sufficient to repress translation in the absence of H2O2. In H2O2-resistant HepG2 cells, H2O2 activated both HCV IRES-mediated and cap-dependent translation, associated with an increased level of phospho-eIF2alpha. It was postulated that H2O2 might stimulate translation in HepG2 cells via an eIF2alpha-independent mechanism, whereas the simultaneous phosphorylation of eIF2alpha repressed part of the translational activities. Indeed, the translational repression was released in the presence of a non-phosphorylatable mutant, eIF2alpha-SA, resulting in further enhancement of both translational activities after exposure to H2O2. In HuH7 cells, which exhibited an intermediate level of sensitivity towards H2O2, both HCV IRES-mediated and cap-dependent translational activities were upregulated after treatment with various doses of H2O2, but the highest level of induction was achieved with a low level of H2O2, which may represent the physiological level of H2O2. At this level, the HCV IRES-mediated translation was preferentially upregulated compared with cap-dependent translation.

Leptin in the field of hepatic fibrosis: a pivotal or an incidental player?

Leptin is a 16-kDa nonglycosylated protein primarily secreted from the adipocytes of white fat; minor levels of regulated leptin expression also occurs at other sites such as placenta, skeletal muscle, the stomach fundus, and culture-activated hepatic stellate cells (HSCs). Leptin is primarily involved in the regulation of food intake and body composition through a central feedback mechanism linking food ingestion, hypothalamus, and adipose tissue mass. In recent years, however, emerging evidence has suggested a critical role of leptin in hepatic inflammation and fibrogenesis and the influence of leptin on chronic liver disease has been an area of active research worldwide. In this review the data on the in vivo and in vitro actions of leptin on liver cells in experimental animal models of liver injury and the effects of leptin on human liver are discussed, with a focus on three distinct fields of chronic liver diseases: nonalcoholic steatohepatitis, alcoholic liver disease, chronic viral hepatitis, and, especially, hepatitis C.

Oxidized proteins and their contribution to redox homeostasis

Proteins are major target for radicals and other oxidants when these are formed in both intra- and extracellular environments in vivo. Formation of lesions on proteins may be highly sensitive protein-based biomarkers for oxidative damage in mammalian systems. Oxidized proteins are often functionally inactive and their unfolding is associated with enhanced susceptibility to proteinases. ROS scavenging activities of intact proteins are weaker than those of misfolded proteins or equivalent concentrations of their constituent amino acids. Protein oxidation and enhanced proteolytic degradation, therefore, have been suggested to cause a net increase in ROS scavenging capacity. However, certain oxidized proteins are poorly handled by cells, and together with possible alterations in the rate of production of oxidized proteins, may contribute to the observed accumulation and damaging actions of oxidized proteins during ageing and in pathologies such as diabetes, arteriosclerosis and neurodegenerative diseases. Protein oxidation may play a controlling role in cellular remodelling and cell growth. There is some evidence that antioxidant supplementation may protect against protein oxidation, but additional controlled studies of antioxidant intake to evaluate the significance of dietary/pharmacological antioxidants in preventing physiological/pathological oxidative changes are needed.

The effect of antioxidant supplementation on hepatitis C viral load, transaminases and oxidative status: a randomized trial among chronic hepatitis C virus-infected patients

OBJECTIVE

To assess the effect of antioxidant supplementation on hepatitis C viral load, transaminases and oxidative status.

METHODS

We performed a randomized, placebo-controlled, double-blind trial to assess the effect of antioxidant supplementation on serum alanine aminotransferase, plasma hepatitis C viral load as well as oxidative and antioxidant markers in patients with hepatitis C virus infection. The participants received a daily dose of ascorbic acid (500 mg), D-alpha-tocopherol (945 IU) and selenium (200 microg) or placebo tablets for 6 months.

RESULTS

Twenty-three patients were included. During supplementation, the antioxidant group had significantly higher levels of plasma ascorbic acid and alpha-tocopherol than the placebo group and the activity of erythrocyte glutathione peroxidase had significantly increased from baseline to month 6. No differences were observed in serum alanine aminotransferase and log10-transformed plasma hepatitis C virus-RNA between the groups or changes from the baseline at any time. No consistent differences between groups or changes from the baseline with respect to erythrocyte activities of antioxidative enzymes (glutathione reductase, superoxide dismutase and catalase) or plasma levels of oxidative markers (malondialdehyde and 2-amino-adipic semialdehyde) were found.

CONCLUSION

Supplementation with vitamin C, E and selenium increased the antioxidant status, but had no effects on alanine aminotransferase, viral load or oxidative markers.

Hepatitis C infection in hemodialysis patients: Protective against oxidative stress?

Hepatitis C virus (HCV) infection is a common problem that increases morbidity and mortality in hemodialysis patients. These patients are also at risk of increased oxidative stress. The aim of this study was to evaluate possible interactions between HCV infection and oxidative stress indicators in a group of hemodialysis patients awaiting transplantation. We evaluated 73 patients (29 women, 44 men; ages, 49.3 +/- 13.3 years; dialysis duration, 81.7 +/- 48.8 months; Kt/V > or = 1.3). Indicators of plasma oxidative status were monitored at the beginning of a clinically stable hemodialysis session. Measurements were performed for plasma superoxide dismutase (SOD), glutathione peroxidase (GPX), and malonyldialdehyde (MDA) by spectrophotometric methods. We retrospectively recorded the prior year's monthly laboratory values for alanine aminotransferase (ALT), C-reactive protein (CRP), albumin, lipids, homocysteine, Lp(a), calcium, phosphorus, intact parathyroid hormone, and predialysis blood urea nitrogen (BUN) creatinine, as well as clinical findings of body mass index and pre- and postdialysis blood pressures. We excluded patients with chronic inflammation (mean CRP levels > or = 10 mg/L) or HCV infection of duration <12 months or clinically advanced liver failure. Twenty-six patients had HCV. The sex distribution, mean age, and dialysis duration were similar between groups. HCV-infected patients showed significantly lower levels of MDA, albumin, total cholesterol, triglyceride, predialysis creatinine, and phosphorus. Antioxidative indicator levels were also higher in the HCV group, but they were not statistically significant. In conclusion, HCV infection in dialysis patients is associated with decreased levels of plasma oxidative load.

Oxidative stress and antioxidant defense in patients with chronic hepatitis C patients before and after pegylated interferon alfa-2b plus ribavirin therapy

Background

Oxidative stress could play a role in pathogenesis of hepatitis C virus (HCV) infection. The aim of our study is to determine oxidant/antioxidant status of patients with chronic hepatitis C (CHC), and the effect of pegylated interferon alfa-2b plus ribavirin combination therapy on oxidative stress.

Methods

Nineteen patients with chronic HCV infection and 28 healthy controls were included in the study. In control and patient groups, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, erythrocyte malondialdehyde (MDA) levels, erythrocyte CuZn-superoxide dismutase (SOD), erythrocyte glutathione peroxidase (GSH-Px) activities were measured. After pegylated interferon alfa-2b and ribavirin combination therapy for 48 weeks, these parameters were measured again in the patient group.

Results

Serum MDA levels increased significantly in CHC patients (n:19), before the treatment when compared with healthy subjects (n:28) 9.28 ± 1.61, 4.20 ± 1.47 nmol/ml, p < 0.001 respectively. MDA concentration decreased significantly (p < 0.001) after the treatment as well as ALT, AST activity, in erythrocytes of these patients. Average antioxidant enzymes (superoxide dismutase and glutathione peroxidase) were significantly lower in erythrocytes of patients with CHC before treatment compared with the control group (both, p < 0.001). Chronic Hepatitis C patients after pegylated interferon alfa-2b and ribavirin therapy showed values of SOD, GSH-Px were significantly higher than pretreatment levels (both, p < 0.001).

Conclusion

Our results show that patients with chronic HCV infection are under the influence of oxidative stress associated with lower levels of antioxidant enzymes. These impairments return to level of healthy controls after pegylated interferon alfa-2b plus ribavirin combination therapy of CHC patients. Although interferon and ribavirin are not antioxidants, their antiviral capacity might reduce viral load, and inflammation, and perhaps through this mechanism might reduce virus-induced oxidative stress.

Studies on oxidative stress in liver diseases: important future trends in liver research

Oxidative stress has recently been shown to play an important role in various liver diseases. Therefore, further studies on oxidative stress in liver diseases are urgently required. In this review, oxidative stress is discussed from the aspects of molecular morphology, metabolism, and aging.

Hepatitis C virus core protein inhibits deoxycholic acid-mediated apoptosis despite generating mitochondrial reactive oxygen species

BACKGROUND

Hepatitis C virus (HCV) core protein is known to cause oxidative stress and alter apoptosis pathways. However, the apoptosis results are inconsistent, and the real significance of oxidative stress is not well known. The aim of this study was twofold. First, we wanted to confirm whether core-induced oxidative stress was really significant enough to cause DNA damage, and whether it induced cellular antioxidant responses. Second, we wanted to evaluate whether this core-induced oxidative stress and the antioxidant response to it was responsible for apoptosis changes.

METHODS

HCV core protein was expressed under control of the Tet-Off promoter in Huh-7 cells and HeLa cells. We chose to use deoxycholic acid (DCA) as a model because it is known to produce both reactive oxygen species (ROS) and apoptosis.

RESULTS

Core expression uniformly increased ROS and 8-hydroxy-2'-deoxyguanosine (8-OHdG) under basal and DCA-stimulated conditions. Core protein expression also increased manganese superoxide dismutase levels. Core protein inhibited DCA-mediated mitochondrial membrane depolarization and DCA-mediated activation of caspase-9 and caspase-3, despite the increase in ROS by DCA. Core protein inhibited DCA-mediated apoptosis by increasing Bcl-x(L) protein and decreasing Bax protein, without affecting the proportion of Bax between mitochondria and cytosol, resulting in suppression of cytochrome c release from mitochondria into cytoplasm.

CONCLUSIONS

HCV core protein induces oxidative DNA damage, whereas it inhibits apoptosis that is accompanied by enhancement of ROS production. Thus, oxidative stress and apoptosis modulation by core protein are independent of each other.

Hepatitis C -- identifying patients with progressive liver injury

Hepatitis C follows a variable course with some patients developing progressive liver fibrosis, cirrhosis and hepatocellular carcinoma, while others have minimal or no significant liver disease after decades of infection. Studies have identified both host and viral factors associated with disease progression. The importance of general factors such as age at infection, gender, immune status and alcohol consumption has long been recognized; however recently, polymorphisms in a wide array of genes have also been shown to be associated with progressive fibrosis. How specific viral proteins may contribute to disease progression has also been studied. This review highlights what is currently known about the factors associated with progressive liver injury in patients with hepatitis C. A greater understanding of the determinants of disease progression will hopefully lead to improved utilization of existing treatments and ultimately may aid in identification of new therapeutic targets.

Hepatitis C virus-core and non structural proteins lead to different effects on cellular antioxidant defenses

Chronic hepatitis C virus (HCV) infection leads to increased oxidative stress in the liver. Hepatic antioxidant enzymes provide an important line of defense against oxidative injury. To understand the antioxidant responses of hepatocytes to different HCV proteins, we compared changes in antioxidative enzymes in HCV-core and HCV-nonstructural protein expressing hepatocyte cell lines. We found that expression of HCV-core protein in hepatocyte cell lines leads to increased oxidative stress as determined by increased in the oxidant-sensitive probe 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-DCFH(2)) fluorescence, decreased reduced glutathione (GSH), and increased oxidation of thioredoxin (Trx). Although the expression of HCV-nonstructural (HCV-NS) proteins led to increased oxidative stress as well, the antioxidant enzymatic responses were different. Over-expression of HCV-NS proteins increased antioxidant enzymes (MnSOD and catalase), heme oxygenase-1 (HO-1), and GSH, indicating different mechanism(s) of prooxidative activity than HCV-core protein. Our findings show that different HCV proteins induce different antioxidant defense responses in hepatocytes. These findings may facilitate understanding the interaction of different HCV proteins with infected liver cells and help identify possible factors contributing to hepatocyte damage during HCV infection.

Hepatic steatosis and the risk of hepatocellular carcinoma in chronic hepatitis C

BACKGROUND AND AIM

Obesity associated hepatic steatosis has been suggested to have a premalignant potential. We determined whether hepatic steatosis predisposes to liver cancer in persons with chronic hepatitis C virus (HCV) infection.

METHODS

We compared the histological severity of steatosis in the index liver biopsies of 25 patients with chronic hepatitis C who subsequently developed hepatocellular carcinoma (HCC) with matched controls who did not. Cases were aged (mean) 54.7 years, 84% males, 76% genotype 1, and 64% fibrosis stage 4; and controls were matched for these characteristics. Those with a sustained virologic response to antiviral therapy were excluded.

RESULTS

Duration of HCV infection, concomitant alcohol intake, body mass index and indices of past hepatitis B virus (HBV) infection were comparable between the groups. Controls were followed for a longer period after the index liver biopsy than were cases (113 months vs 55 months, P < 0.001). As determined by percentage area of biopsy core occupied by steatosis on computer assisted morphometric evaluation, and graded by semiquantitative histological assessment, steatosis was comparable among cases and controls. The odds of developing HCC among those with steatosis grades 1 and 2 did not differ significantly from those without steatosis. There was no association between increasing morphometric percentage area occupied by steatosis and the subsequent development of HCC. Neither steatosis grade or percent area of steatosis on biopsy were selected in multivariate regression analysis as independent predictors for the development of HCC.

CONCLUSIONS

Hepatic steatosis does not augment the risk of hepatocarcinogenesis in patients with chronic HCV infection.

In situ detection of oxidized n-3 polyunsaturated fatty acids in chronic hepatitis C: correlation with hepatic steatosis

BACKGROUND

Oxidative stress contributes to the pathogenesis of chronic hepatitis C. The aim of this study was to assess the peroxidation of n-3 polyunsaturated fatty acids (PUFAs) in the liver and its relation to hepatic steatosis in chronic hepatitis C.

METHODS

We immunohistochemically detected malondialdehyde (MDA)-, 4-hydroxy-2-nonenal (HNE)-, and 4-hydroxy-2-hexenal (HHE)-protein adducts in liver biopsy specimens from 55 patients with chronic hepatitis C. Cells stained positively for HHE-protein adducts were quantified using computer-based image analysis. Fatty-acid composition was determined, by gas chromatography, for the noncancerous portions of resected livers, with or without steatosis, obtained from two patients with hepatitis C virus-associated hepatocellular carcinoma.

RESULTS

The detection rate of HHE-protein adducts (63.6%) was significantly higher than that of MDA-protein adducts (21.8%; P < 0.001) or HNE-protein adducts (29.1%; P < 0.001). Areas positively stained for HHE-protein adducts (HHE-positive areas) were significantly larger in 18 patients with steatosis (6.2 +/- 3.6%) than in 17 patients without steatosis (3.4 +/- 2.6%; P = 0.01). Resected liver tissue with steatosis showed a larger HHE-positive area (18.6%) and higher ratio of n-6 PUFA content to n-3 PUFA content (3 : 1) than liver tissue without steatosis (7.2%; 2 : 3). On multivariate analysis, the HHE-positive area (odds ratio, 1.55; 95% confidence interval [CI], 1.08-2.23; P = 0.019) was a factor associated with the presence of hepatic steatosis.

CONCLUSIONS

HHE-protein adducts, which are a good marker for oxidative stress, are associated with steatosis in chronic hepatitis C.

Association of myeloperoxidase promotor polymorphism with cirrhosis in patients with hereditary hemochromatosis

BACKGROUND/AIMS

Hereditary hemochromatosis (HHC) is a disorder of iron metabolism with variable penetrance. Oxidative stress plays a central role in the progression to cirrhosis. Several enzymes involved in the production or degradation of reactive oxidants, like myeloperoxidase (MPO) and heme oxygenase (HO)-1 are influenced by promotor polymorphisms. This study assessed the impact of polymorphisms of the MPO (-463G/A) and the HO-1 promotors of Vienna (GT)n on the evolution of cirrhosis in patients with HHC.

METHODS

One-hundred and fifty-eight C282Y homozygotes without cofactors for fibrosis progression (119 males; mean age: 51.0+/-13.3) were studied. All patients underwent liver biopsy. Hepatic iron content was measured by atom absorption spectrophotometry. MPO polymorphism was assessed by RFLP analysis; HO-1 microsatellite polymorphism by a laser-based semi-automated DNA sequencer.

RESULTS

The MPO genotypes GG, GA, and AA were found in 102 (64.6%), 45 and 11 patients, respectively. The GG-genotype was more common in patients with cirrhosis than in those without (78.7 vs. 55.7%, P=0.003). The distribution of HO-1 genotypes was not different. Logistic regression analysis revealed MPO genotype-GG, serum ferritin, age and male sex as independent predictors for cirrhosis.

CONCLUSIONS

MPO genotype GG is associated with cirrhosis in patients with hereditary hemochromatosis.

Antioxidant levels in peripheral blood, disease activity and fibrotic stage in chronic hepatitis C

BACKGROUND

This study addressed the suggested association between levels of the antioxidants glutathione (GSH), vitamin C and vitamin E in peripheral blood and the histological activity and fibrosis stage in chronic hepatitis C (CHC). We then determined whether regular antioxidant supplementation influenced these antioxidant levels or disease severity.

METHODS

Clinical, biochemical, histological and demographic data were collected from 247 CHC patients at the time of liver biopsy. Whole blood total GSH, plasma vitamin C and E were assessed by high-performance liquid chromatography. Statistical analyses were performed to test for associations between the variables and to identify independent predictors for hepatic necroinflammatory and fibrosis scores.

RESULTS

GSH and vitamin C, but not vitamin E correlated with both portal/periportal activity (r = -0.19, P = 0.004; r = -0.19, P = 0.009 respectively) and fibrosis stage (r = -0.18, P = 0.007; r = -0.18, P = 0.009 respectively). GSH was an independent negative predictor of portal/periportal inflammation (P = 0.02) and fibrosis (P = 0.01). Vitamin C was an independent negative predictor of fibrosis stage (P = 0.02). Antioxidant intake was associated with higher vitamin C (P < 0.0001) and vitamin E (P = 0.005) levels, but not GSH.

CONCLUSIONS

Whole blood GSH and plasma vitamin C are negatively associated with hepatic portal/periportal inflammation and fibrosis stage in CHC. Controlled intervention studies with vitamin C and agents that boost endogenous GSH levels are warranted.

Hepatocyte steatosis is an important predictor of response to interferon (IFN) monotherapy in Japanese patients infected with HCV genotype 2a: Virological features of IFN-resistant cases with hepatocyte steatosis

The role of hepatocyte steatosis in interferon (IFN) resistance is still unclear, especially in patients infected with hepatitis C virus (HCV) genotype 2a. The present study was conducted in 364 consecutive non-cirrhotic naive patients infected with genotype 2a, who were evaluated for the severity of steatosis and response to IFN monotherapy after a 24-week median duration of therapy. The patients were examined for factors associated with steatosis and treatment efficacy according to the grade of steatosis. Early viral kinetics was also evaluated in 64 patients for predictors of response to therapy. Nine IFN-resistant patients were assessed for the relationship between amino acid sequence of HCV core region/NS5A and severity of steatosis. Multivariate analysis identified two independent factors associated with steatosis; serum ferritin > or =200 microg/l and body mass index > or =25.0 kg/m(2). The sustained virological response rate in patients with high-grade steatosis was significantly lower than in the low-grade group. Study of early viral kinetics showed a significantly lower cumulative HCV-RNA negative rate for the high-grade than low-grade steatosis group. Sequence analysis of HCV core region/NS5A in IFN-resistant patients with or without steatosis failed to identify steatosis-specific amino acid substitutions associated with resistance. This study of HCV genotype 2a suggested that steatosis is associated with excess iron storage, and that it is an important predictor of efficacy of IFN monotherapy. Further large-scale studies are warranted to examine the role of amino acid substitutions on IFN resistance specific for steatosis.

Circulating markers of oxidative stress and liver fibrosis in Sudanese subjects at risk of schistosomiasis and hepatitis

Epidemiological studies in the developing world are frequently biased by the simultaneous presence of several infectious pathogens. In the present study, we examined the usefulness of circulating markers of oxidative stress and liver fibrosis to investigate the distinct forms of chronic liver inflammations associated with schistosomiasis and viral hepatitis, respectively. The study was performed in a Sudanese population exposed to Schistosoma. Circulating hyaluronic acid (HA) was used as a marker of liver fibrosis; the severity of schistosomiasis was determined by ultrasonic examination; viral hepatitis infection was ascertained by circulating anti-hepatitis antibodies. Serum markers were examined also in Sudanese subjects not exposed to Schistosoma infection and in French control subjects. We found a drastic decrease of lycopene levels in the subjects exposed to schistosomiasis in comparison with non-exposed Sudanese and French control subjects. Retinol, alpha-tocopherol and five carotenoids were unchanged. Lycopene depletion was unlikely to be due to variations of nutritional origin, since the lycopene/beta-carotene ratio was five-fold lower in the population at risk of schistosomiasis than in the other groups. We found that high HA serum levels were associated with severe periportal fibrosis but not with viral infection. Conversely, levels of the oxidized lipid malondialdehyde (MDA) were associated with viral infection but not with the severity of schistosomiasis, even though the two infections had additive effects. We concluded that serum markers are valuable tools for investigating the complex effects of co-existing factors of chronic liver inflammation.

Hepatitis intensified oxidative stress, MIP-1beta and RANTES plasma levels in uraemic patients

HBV and HCV infections are associated with the increased production of reactive oxygen species (ROS) within the liver that are responsible for the oxidation of intracellular molecules and activation transcription factors. The aim of the present study was to establish whether the presence of hepatitis could be implicated in the elevation of oxidative stress (SOX) and plasma proinflammatory and chemoattractant cytokine levels in uraemic patients. The markers of SOX-autoantibodies to oxidized LDL (OxLDL-Ab); total peroxides; and the major antioxidant enzyme Cu/Zn superoxide dismutase (Cu/Zn SOD); as well as tumor necrosis factor-alpha (TNF-alpha); regulated upon activation, normal T cell expressed and secreted (RANTES); and macrophage inflammatory protein-1alpha (MIP-1alpha) and beta (MIP-1beta) levels were measured in the plasma of uraemic patients with hepatitis in comparison to subjects without hepatitis and to healthy volunteers. The values of total peroxide, Cu/Zn SOD, TNF-alpha, and MIP-1beta, were significantly elevated in uraemic patients when compared to the controls, whereas RANTES were decreased. MIP-1alpha and OxLDL-Ab were similar in the two groups. Cu/Zn SOD, MIP-1beta and RANTES concentrations were significantly higher in the hepatitis-positive relative to the hepatitis-negative group. Both MIP-1beta and RANTES were directly associated with Cu/Zn SOD levels and the presence of hepatitis. Multiple stepwise regression analysis has shown that the duration of dialysis, followed by the presence of hepatitis, independently and significantly predicted increased Cu/Zn SOD levels, whereas elevated Cu/Zn SOD as an independent variable was significantly associated with both increased both MIP-1beta and RANTES in uraemic patients. These results suggest that the presence of viral hepatitis status and liver injury are novel determinants of increased oxidative stress, as well as of increased MIP-1beta and RANTES levels in uraemic patients.

Pathogenesis of hepatitis C-associated hepatocellular carcinoma

Epidemiologic, clinical, and virologic data have shown a close association between chronic infection with hepatitis C virus (HCV) and the development of hepatocellular carcinoma (HCC). In many countries of the developed world, HCV infection accounts for more than half of the cases of HCC. HCC usually arises after 2-4 decades of infection, typically in the context of an underlying cirrhosis. Treatment of hepatitis C with interferon-alfa can lead to sustained clearance of HCV, and small prospective studies as well as larger retrospective analyses suggest that interferon therapy leads to a decrease in the incidence of HCC. Without a reliable tissue culture system or a small animal model of HCV infection, analysis of the mechanisms by which HCV leads to cancer has been difficult. Nevertheless, both in vitro expression systems and in vivo transgenic mice studies suggest that HCV has an inherent carcinogenic potential. Understanding the pathogenesis of HCV-associated HCC is important in developing effective means of prevention and treatment of this highly malignant form of cancer.

Reactions of 4-hydroxynonenal with proteins and cellular targets

Peroxidative degradation of lipids yields the aldehyde 4-hydroxy-2-nonenal (4HNE) as a major product. The lipid aldehyde is an electrophile, and reactivity of 4HNE toward protein nucleophiles (i.e., Cys, His, and Lys) has been characterized. Through the use of purified enzymes and isolated cells, various pathways for biotransformation of the lipid aldehyde have been identified and include enzyme-mediated oxidation, reduction, and glutathione conjugation. Uncontrolled oxidative stress can yield excessive lipid peroxidation and 4HNE generation, however, and overwhelm these cellular defenses. Indeed, in vitro and in vivo production of 4HNE in response to pro-oxidant exposure has been demonstrated using antibodies to protein adducts of the lipid aldehyde. Recent evidence suggests a role for protein modification by 4HNE in the pathogenesis of several diseases (e.g., alcohol-induced liver disease); however, the precise mechanism(s) is currently unknown but likely results from adduction of proteins involved in cellular homeostasis or biological signaling.