Influence of chronic alcohol abuse on hepatitis C virus replication

A New Perspective on Fish Oil: The Prevention of Alcoholic Liver Disease

The mechanisms of alcoholic liver diseases (ALD) are very complex and interrelated, including abnormal lipid metabolism, oxidative stress, and gut-derived endotoxin pathway. On the other hand, fish oil is rich in n-3 polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which decrease blood triglyceride concentration in hypertriglycemia patients and show protective effects against fatty liver. However, there is limited evidence from studies of the relationship between fish oil and ALD based on the viewpoint of the intestinal integrity and microflora. Therefore, this review discusses the mechanism of amelioration for ALD by fish oil. Based on our previous studies, partial replacement of olive oil by fish oil in alcohol-containing liquid diet ameliorated the liver damage including fatty liver and inflammation in rats. Based on these results, the mechanisms of hepatoprotective effects due to fish oil substitution were discussed in three parts, such as regulating lipid metabolism, decreasing oxidative stress and maintaining intestinal health. First of all, we found that fish oil substitution increased plasma adiponectin levels, and then increasing MCAD and CPT-1 mRNA levels to accelerate fatty acid oxidation in liver, then further prevent ethanol-induced hepatosteatosis in rats with chronic alcohol-feeding. Fish oil replacement also enhanced hepatic autophagy flux, which enhanced lipid degradation, then inhibited lipid accumulation in liver. Secondly, the appreciable proportion of fish oil decreased lipid peroxidation by reducing the protein expression of cytochrome p450 2E1 in chronic alcohol-feeding rats. We also speculated that the appropriate proportion of n-6 and n-3 PUFAs is very important for preventing alcoholic liver disease. At last, substituting fish oil for olive oil normalized the intestinal permeability and fecal microbiota composition, thus providing a low plasma endotoxin level and inflammatory responses, which exert ameliorative effects on ethanol-induced liver injuries in rats.

Effects of Fish Oil on Lipid Metabolism and Its Molecular Biological Regulators in Chronic Ethanol-Fed Rats

The purpose of this study was to clarify the hepatoprotective mechanisms of fish oil in ethanol-fed rats based on lipid metabolism. Thirty eight-week-old male Wistar rats were divided into six groups: C (control), CF25 (control diet with 25% fish oil substitution), CF57 (control diet with 57% fish oil substitution), E (ethanol-containing diet) group, EF25 (ethanol-containing diet with 25% fish oil substitution), and EF57 (ethanol-containing diet with 57% fish oil substitution) groups. All of the groups were pair-fed an isoenergetic diet based on E group. Rats were sacrificed after eight weeks. When compared with C group, the plasma aspartate transaminase (AST) activity and hepatic steatosis and inflammatory cell infiltration were significantly higher, while plasma adiponectin level and hepatic AMP-activated protein kinase α (AMPKα) protein expression was significantly lower in the E group. However, the hepatic damage, including steatosis and inflammation were ameliorated in the EF25 and EF57 groups. Moreover, mRNA levels of fatty acid-oxidative enzymes, such as medium-chain acyl-coenzyme A dehydrogenase (MCAD) and carnitine palmitoyltransferase I (CPT-1) were significantly elevated in the EF57 group than those in E group. Partial replacement with fish oil might improve the fatty acid oxidation by raising mRNA levels of downstream transcription factors, finally inhibit the ethanol-induced hepatic steatosis in rats.

Update on Alcohol and Viral Hepatitis

Alcohol consumption is often associated with viral hepatitis. Although alcohol is known to worsen viral liver disease, the interactions between alcohol and viral hepatitis are not fully understood. Molecular alterations in the liver due to alcohol and viral hepatitis include effects on viral replication, increased oxidative stress, cytotoxicity, and a weakened immune response. Clinically, alcohol enhances disease progression and favors induction of primitive liver neoplasm. The use of new antivirals for hepatitis C and well-established drugs for hepatitis B will determine how viral hepatitis can be controlled in a large percentage of these patients. However, alcohol-related liver disease continues to represent a barrier for access to antivirals, and it remains an unresolved health issue.

Update on Alcohol and Viral Hepatitis

Alcohol consumption is often associated with viral hepatitis. Although alcohol is known to worsen viral liver disease, the interactions between alcohol and viral hepatitis are not fully understood. Molecular alterations in the liver due to alcohol and viral hepatitis include effects on viral replication, increased oxidative stress, cytotoxicity, and a weakened immune response. Clinically, alcohol enhances disease progression and favors induction of primitive liver neoplasm. The use of new antivirals for hepatitis C and well-established drugs for hepatitis B will determine how viral hepatitis can be controlled in a large percentage of these patients. However, alcohol-related liver disease continues to represent a barrier for access to antivirals, and it remains an unresolved health issue.

Molecular mechanisms involved in the interaction effects of alcohol and hepatitis C virus in liver cirrhosis

The mechanisms by which alcohol consumption accelerates liver disease in patients with chronic hepatitis C virus (HCV) are not well understood. To identify the characteristics of molecular pathways affected by alcohol in HCV patients, we fit probe-set level linear models that included the additive effects as well as the interaction between alcohol and HCV. The study included liver tissue samples from 78 patients, 23 (29.5%) with HCV-cirrhosis, 13 (16.7%) with alcohol-cirrhosis, 23 (29.5%) with HCV/alcohol cirrhosis and 19 (24.4%) with no liver disease (no HCV/no alcohol group). We performed gene-expression profiling by using microarrays. Probe-set expression summaries were calculated by using the robust multiarray average. Probe-set level linear models were fit where probe-set expression was modeled by HCV status, alcohol status, and the interaction between HCV and alcohol. We found that 2172 probe sets (1895 genes) were differentially expressed between HCV cirrhosis versus alcoholic cirrhosis groups. Genes involved in the virus response and the immune response were the more important upregulated genes in HCV cirrhosis. Genes involved in apoptosis regulation were also overexpressed in HCV cirrhosis. Genes of the cytochrome P450 superfamily of enzymes were upregulated in alcoholic cirrhosis, and 1230 probe sets (1051 genes) had a significant interaction estimate. Cell death and cellular growth and proliferation were affected by the interaction between HCV and alcohol. Immune response and response to the virus genes were downregulated in HCV-alcohol interaction (interaction term alcohol*HCV). Alcohol*HCV in the cirrhotic tissues resulted in a strong negative regulation of the apoptosis pattern with concomitant positive regulation of cellular division and proliferation.

Alcohol and viral hepatitis: a mini-review

Due to their high prevalence in the general population, alcohol use and abuse can be associated with hepatitis B and C virus infections and it has been demonstrated that alcohol plays a role as a co-morbid factor in the development of liver disease. There is evidence that alcohol abuse accelerates the progression of liver fibrosis and affects the survival of patients with chronic hepatitis C. The mechanism by which alcohol worsens hepatitis C virus-related liver disease has not been fully clarified, but enhanced viral replication, increased oxidative stress, cytotoxicity and impairment of immune response could play a relevant role. Alcohol abuse also seems to reduce both sensitivity to interferon and adherence to treatment. It sounds reasonable to presume that the mechanisms enhancing liver damage in patients affected by hepatitis B are similar to those involved in hepatitis C virus infection. However, more studies are warranted to improve our knowledge about the interaction between alcohol intake and hepatitis B virus infection. In conclusion alcohol abuse is associated with an accelerated progression of liver injury, leading to an earlier development of cirrhosis, higher incidence of hepatocellular carcinoma, and higher mortality. Abstinence could reverse some of these deleterious effects.

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.

Mechanisms of synergy between alcohol and hepatitis C virus

BACKGROUND

Since the discovery of the hepatitis C virus (HCV), extensive literature has emerged on alcohol and HCV interaction.

GOAL

To understand the impact of alcohol and HCV infection on the severity of liver disease and the mechanisms of interaction between the two.

STUDY

Of 1269 articles (1991 to 2006) searched through MEDLINE and cited cross references, 133 were thoroughly reviewed to assess: (a) prevalence of combined alcohol use and HCV, (b) severity of liver disease (c) treatment response, and (d) mechanisms of interaction between HCV and alcohol. Data on study design, patient demographics, diagnostic tests used, and study outcomes were extracted for critical analysis.

RESULTS

Prevalence of HCV is 3-fold to 30-fold higher in alcoholics compared with the general population. Patients with HCV infection and alcohol abuse develop more severe fibrosis with higher rate of cirrhosis and hepatocellular cancer compared with nondrinkers. Increased oxidative stress seems to be the dominant mechanism for this synergism between alcohol and the HCV. Abstinence is the key to the management of liver disease due to HCV and alcohol. Data have shown that lower response rates to interferon in alcoholics with HCV infection are likely due to noncompliance.

CONCLUSIONS

Alcoholics with HCV infection have more severe liver disease compared with nondrinkers. Patients should be encouraged to enroll in rehabilitation programs so as to improve treatment adherence and response.

Low density lipoprotein receptor transcripts correlates with liver hepatitis C virus RNA in patients with alcohol consumption

Alcohol consumption has a major impact on the natural history of chronic hepatitis C virus (HCV) infection, although the underlying mechanisms are still debated. We designed a clinical study to evaluate the impact of alcohol abuse on both viral load and expression of low-density lipoprotein receptor (LDLR) and CD81 expression. Thirty-eight consecutive HCV-infected patients were enrolled. Group 1 (n = 18), < or =10 g alcohol/day, group 2 (n = 8), < or =30 g alcohol/day, group 3 (n = 12), >or =30 g alcohol/day. Receptors expression was measured by flow cytometry analysis in peripheral blood mononuclear cells (PBMC) and by specific real-time retrotranscription polymerase chain reaction (RT-PCR) in the liver. Serum viral load was evaluated by quantification of both HCV genomic RNA and total core antigen. The hepatic viral load was assessed by real-time RT-PCR. Serum HCV-RNA and total core antigen were significantly correlated, and were higher, albeit not significantly, in group 3 than in group 1. Alcohol consumption had no effect on expression of HCV putative receptors in PBMC, except for CD81, which was upregulated on monocytes in group 2. In the liver, viral load and levels of LDLR transcripts were significantly higher in group 3 than in group 1. Remarkably, a significant positive correlation was found between LDLR transcripts and HCV-RNA (r2 = 0.83, P < 10(-3)). Finally, in vitro experiments suggested that the effect of ethanol on LDLR expression was indirectly mediated by both tumour necrosis factor-alpha and interleukin-1beta. In conclusion, this study is the first to support a role for LDLR in the natural infection by HCV in man.

Drug interactions between psychoactive substances and antiretroviral therapy in individuals infected with human immunodeficiency and hepatitis viruses

The liver disease characteristic of alcohol dependence encompasses three main related entities: steatosis, alcoholic hepatitis, and cirrhosis. Alcoholic cirrhosis is a leading cause of global morbidity and mortality. Alcohol intake among injecting drug users is a major contributor to transmission of viral infections, such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C viruses (HCV). HIV and HCV coinfected patients develop liver diseases earlier and more severely than the monoinfected individuals, including hepatocellular carcinoma. Interactions exist between the therapeutic drugs used to minimize and control the drug and alcohol dependence. Furthermore, drug-drug interactions occur between the highly active antiretroviral therapy (HAART) and alcohol, different HAART components and methadone, or each one of the therapies with the other, thus contributing to a higher toxicity level. With the evolution of effective antiretroviral therapy, survival of persons with HIV, and the syndrome it causes, acquired immunodeficiency syndrome (AIDS) has increased dramatically. Drug-drug interactions may appear between alcohol and anti-HBV or anti-HCV, therapy in the presence or absence of anti-HIV therapy. Several other medical-, social-, and drug-related factors of this population have to be considered when providing HAART. Because many coinfected patients also have problems with substance use, dealing with their drug dependence is an important first step in an attempt to improve adherence to and tolerance of antiviral therapy. It is necessary to minimize the risk of liver disease acceleration and/or reinfection with hepatitis viruses. Knowledge of potential drug interactions between methadone, antiretroviral therapy, psychoactive drugs, and antipsychotics and the role of coinfection with HBV or HCV and the drugs used in eradicating viral hepatitis permits suitable antiretroviral combinations.

Alcohol has no effect on hepatitis C virus replication: a meta-analysis

BACKGROUND

Patients with chronic hepatitis C virus (HCV) infection who consume large quantities of alcohol have more severe liver disease compared with HCV patients without a history of alcohol consumption. The mechanism by which alcohol worsens HCV related liver disease is not properly understood. One possibility is that alcohol stimulates HCV replication, and the present meta-analysis was performed to examine this issue.

METHODS

The effect of alcohol on viral titres was assessed in three ways: comparison of the heaviest drinkers with non-drinkers; effect of graded doses of alcohol; and effect of abstinence in the same individual.

RESULTS

A total of 14 studies were identified. Comparison of patients with the highest alcohol use with the abstinent group showed a significant association with viral load in three studies, five studies had a positive direction, while the remaining four studies found a negative relationship. Analysis of the combined results showed no association between alcohol consumption and virus levels (p = 0.29). Assessment of graded doses of alcohol also showed no significant difference between non-drinkers and moderate drinkers (p = 0.50), between non-drinkers and heavy drinkers (p = 0.35), or between moderate drinkers and heavy drinkers (p = 0.32). Five studies examined the influence of abstinence on viral titres but none provided sufficient data for statistical analysis.

CONCLUSIONS

The present study has failed to show an association between alcohol use and HCV viral titres. These observations raise the possibility that the hepatic damage caused by alcohol and HCV may be purely additive, involving different mechanisms and pathways.

Rescue of in vivo FAS-induced apoptosis of hepatocytes by corticosteroids either associated with alcohol consumption by mice or provided exogenously

The pathogenic effects of many hepatic viral infections are mediated, at least in part, by the immune response to the infected hepatocyte. The immune response in the infected liver involves the interaction of cytotoxic T cells (CTL) with the hepatocytes through the interaction of FAS-ligand on the CTL and FAS on the hepatocyte. The initial hypothesis for this study was that alcohol consumption by mice would sensitize the liver to apoptosis induced by ligation of FAS. C57Bl/6 mice fed ethanol in a liquid diet did show an increased percentage of apoptotic cells 2 h after injection with anti-FAS as compared with the percentage in the control mice. However, 4 and 6 h after anti-FAS injection, control mice showed high percentages of apoptotic cells (20% to 41%) compared with 5% and 4% apoptotic cells in the ethanol-fed mice. The decreased apoptosis of ethanol-fed mice correlated closely with corticosterone levels in the sera. This was confirmed by the finding that adrenalectomized (ADX) mice provided a high level of corticosterone in drinking water were protected against FAS-induced hepatocyte apoptosis. Ethanol-fed mice showed a significant elevation of serum alanine aminotransferase (ALT) levels indicating the development of hepatitis in spite of the relatively low proportion of apoptotic cells in the liver. In conclusion, high levels of corticosterone protect hepatocytes from FAS-mediated apoptosis, but do not prevent the ultimate development of liver damage. In experiments where mice were provided ethanol chronically in drinking water, where stress is minimal, higher levels of ALT were noted in animals in the ethanol group as compared with animals in the control group. These data support the suggestion that ethanol increases hepatocyte sensitivity to FAS-mediated damage.

Treatment of chronic hepatitis C in patients with drug dependence: time to change the rules?

AIMS

Approximately 170 million people world-wide are chronically infected with the hepatitis C virus (HCV). While the seroprevalence in the general population ranges between 0.2 and 2%, 50-90% of injection drug users are chronically HCV-infected. However, most patients who are drug abusers are still excluded from treatment of chronic HCV infection with interferon (IFN)-alpha. Due to the recent treatment advances resulting in sustained response rates between 50 and 80%, it becomes increasingly important to reflect the still existing contraindications and restrictions for IFN-alpha treatment, especially for patients with intravenous drug use (IDU) with or without psychiatric comorbidity.

METHODS

We reviewed clinical trials that focus on the treatment of chronic hepatitis C in patients with drug addiction published between 1987 and 2003.

FINDINGS

Only seven clinical trials investigating HCV treatment among drug users were found: four open prospective uncontrolled trials and three controlled trials. Thus far, no trials using pegylated IFN-alpha have been conducted. Data about sustained response and adherence in HCV-infected methadone substituted patients were either comparable to control groups or to representative clinically controlled trials using the same treatment regimen (IFN-alpha monotherapy or combined with ribavirin). Patients with former or present drug abuse seem more likely to discontinue treatment early. HCV-infected IDUs tended to be older with higher inflammatory activity and stage of fibrosis when interferon treatment was started. Psychiatric comorbidity did not negatively influence adherence or treatment outcome.

CONCLUSIONS

There is no clinical evidence suggesting that HCV treatment with IFN-alpha should be limited to IDUs or methadone substituted patients. However, more prospective controlled trials on HCV treatment for patients with IDU are needed to establish and apply new rules and guidelines.

Additive inhibition of dendritic cell allostimulatory capacity by alcohol and hepatitis C is not restored by DC maturation and involves abnormal IL-10 and IL-2 induction

BACKGROUND

Excessive alcohol use results in impaired immunity, and it is associated with increased incidence and progression of chronic hepatitis C virus (HCV) infection. Here we investigated the effects of HCV infection and alcohol on myeloid dendritic cells (DC) that are critical in antiviral immunity.

METHODS

Immature and mature DCs were generated from monocytes of chronic HCV infected patients (HCV-DC) and controls (N-DC) with IL-4 plus granulocyte-macrophage colony stimulating factor (GM-CSF) in the presence or absence of alcohol (25 mM). DC allostimulatory capacity was tested in mixed lymphocyte reaction (MLR) and cytokine production by ELISA.

RESULTS

Allostimulatory capacity of HCV-DCs was reduced compared to N-DCs and it was further inhibited by alcohol treatment (p < 0.01). MLR was also decreased with alcohol-treated N-DCs. DC phenotypic markers and apoptosis were comparable between HCV-DCs and N-DCs irrespective of alcohol treatment. However, HCV-DCs and alcohol-treated N-DCs exhibited elevated IL-10 and reduced IL-12 production. Reduced MLR with HCV-DCs and its further inhibition by alcohol coexisted with decreasing IL-2 levels (p < 0.017). DC maturation partially improved but failed to fully restore the reduced allostimulatory function of either alcohol-treated or alcohol-naïve HCV-DCs (p < 0.018).

CONCLUSIONS

Alcohol and HCV independently and together inhibit DC allostimulatory capacity, increase IL-10, reduce IL-12 and IL-2 production that cannot be normalized by DC maturation. HCV and alcohol interact to modulate innate and adaptive immune responses via dendritic cells.

Hepatitis C and alcohol: interactions, outcomes, and implications

BACKGROUND

Alcoholism and chronic hepatitis C (HCV) infection are common causes of liver disease worldwide. Hepatitis C virus and alcohol use frequently coexist, and together lead to more rapid progression of liver disease.

GOALS

To critically review the literature pertaining to the combined effects of alcohol and HCV, focusing primarily on how alcohol influences the natural history, pathogenesis, and treatment of HCV liver disease.

STUDY

A thorough review of the English literature was conducted, using a MEDLINE-based computerized literature search and review of cited references.

RESULTS

Hepatitis C virus is prevalent in unselected alcoholic populations (14-36%) and in alcoholic individuals with liver disease (< or =51%). Hepatitis C virus-infected individuals who drink alcohol in excess have more severe histologic injury, more rapid disease progression, and a higher frequency of cirrhosis and hepatocellular carcinoma. Alcohol use also appears to decrease response rates to interferon therapy. The mechanisms of interaction between alcohol and HCV are not fully understood, but they likely include the effects of alcohol on the host immune system and the virus and on other factors possibly related to HCV liver disease and hepatic carcinogenesis.

CONCLUSIONS

Alcohol use and HCV infection frequently coexist. Although there is ample evidence that alcohol use adversely affects the natural history of HCV liver disease, how the two interact is not well understood. Patients with chronic HCV should be encouraged to avoid alcohol; however, the threshold above which alcohol results in accelerated liver disease remains to be determined.

Pathogenic interactions between alcohol and hepatitis C

Alcohol is the most commonly abused substance in the United States, and alcohol abuse leads to alcoholic liver disease, a long recognized major public health concern. The high prevalence of chronic hepatitis C virus (HCV) infection, along with the clinical observation that HCV infection is common in alcoholic patients presenting with liver disease, has directed attention to the interaction between alcohol and HCV infection. Clinical studies have identified alcohol use as an independent risk factor for progression of fibrosis in chronic HCV infection. Experimental evidence suggests additive inhibitory effects between HCV and alcohol on antiviral immune responses. In addition, specific pathways have been identified by which HCV core protein and alcohol interact to activate hepatocytes. Nonspecific inflammatory cell recruitment and proinflammatory cytokine activation have also been implicated in both alcohol- and HCV-induced liver diseases. Further investigation of these and other pathways by which alcohol and HCV interact should unravel the mechanisms that accelerate the progression of liver disease.

Role of activated CD8+ T cells in the initiation and continuation of hepatic damage

The cause of alcoholic liver disease (ALD) is multifactorial and poorly understood. It is clear that alcohol alone is not responsible for most of the changes associated with ALD and that cofactors are involved in initiation and production of ALD. One cofactor that has received a great deal of attention recently is the concomitant infection with hepatitis C virus (HCV) and alcohol abuse. The interactive effects of HCV and alcohol abuse are still unclear, but apparently they are the result of an inability of the immune system to control the viral infection and exaggerated hepatocyte damage mediated by either the cells of the inflammatory response or factors produced by the inflammatory cells. This review will focus on one aspect of the possible pathogenic effects associated with alcohol abuse and HCV infection: the possible role of the immune system, notably the cytotoxic T lymphocyte (CTL) response. It is clear that the development of a CTL response is critical for the control of HCV infections, and it is also likely that this response is involved in liver damage. In this review, the evidence that shows the importance of the CD8(+) CTL in viral clearance and the role for pathogenesis will be presented. Findings obtained from animal studies that support the suggestion that activated CD8(+) CTLs can induce liver damage will be presented, as will results of recent studies from my laboratory that provide evidence for an effect of alcohol to enhance the liver damage mediated by activated CD8(+) T cells.

Does hepatitis C virus cause severe liver disease only in people who drink alcohol?

Hepatitis C virus (HCV) infects about 170 million people worldwide, and has been portrayed in the media as a silent killer, incorrectly implying that cirrhosis and hepatocellular carcinoma are the certain final outcomes of infection. Results of numerous population-based surveys indicate that chronic HCV infection is highly prevalent in elderly people who, in most instances, do not develop end-stage liver disease. In individuals who do progress to cirrhosis and hepatocellular carcinoma alcohol plays a fundamental part, via mechanisms that result in increased viral replication, enhanced HCV quasispecies complexity, increased liver-cell death, suppression of immune responses, and iron overload. Although overlaps are present in the histological appearance of the liver in patients with hepatitis C who do and do not drink alcohol, histology could be of some help in revealing the role of alcohol in HCV disease progression even in people who deny drinking. Interventions and high-impact, continuous public-health campaigns are needed to persuade doctors and patients infected with HCV of the importance of abstaining from alcohol if risk of progression towards cirrhosis and hepatocellular carcinoma is to be reduced.