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Alcohol May Affect Progression of Hepatitis C & Interferon Efficacy
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The journal Hepatology published a NIH study in the July issue and study findings raise serious questions regarding alcohol use by HCV-infected individuals. A second article was also published in this issue of Hepatology on alcohol use & HCV, and both articles are discussed below.
NATIONAL INSTITUTES OF HEALTH PRESS RELEASE
ALCOHOL INCREASES HEPATITIS C VIRUS IN HUMAN CELLS
Drinking May Compromise Treatment Success
A team of NIH-supported researchers today report that alcohol increases replication of the hepatitis C virus (HCV) in human cells and, by so doing, may contribute to the rapid course of HCV infection. The researchers tested the actions of alcohol in HCV replicon - viral HCV-ribonucleic acid or HCV-RNAs that, when introduced into human liver cell lines, replicate to high levels. In
separate laboratory experiments they showed that:
-- alcohol increases HCV replication at least in part by upregulating a key cellular regulator of immune pathways and function known as nuclear factor kappa B;
-- alcohol inhibits the anti-HCV effect of interferon-alpha therapy; and
--treatment with the opioid antagonist naltrexone abolishes alcohol actions.
"These findings are immediately useful to clinicians for counseling HCV-positive patients about alcohol use," said Ting-Kai Li, M.D., Director, National Institute on Alcohol Abuse and Alcoholism (NIAAA).
Clinicians have long observed a high incidence of HCV infection in heavy drinkers, including those without other risk factors such as intravenous drug
abuse or history of blood transfusions. In addition, the virus is more likely
to persist in heavy drinkers and to lead to such complications as cirrhosis and liver cancer. Suspected mechanisms for the latter effects include alcohol's
capacity to compromise immune function and enhance oxidative stress. The role of alcohol use in HCV acquisition has been more of a mystery.
Alcohol potentiates hepatitis C virus replicon expression
Hepatology July 2003, Volume 38, Number 1
Ting Zhang1-2, Yuan Li1, Jian-Ping Lai1, Steven D. Douglas1, David S. Metzger3, Charles P. O'Brien3, Wen-Zhe Ho1. Division of Allergy and Immunology, Joseph Stokes Jr. Research Institute at The Children's Hospital of Philadelphia, Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA; the 2Department of Infectious Diseases, The Children's Hospital of Fudan University, Shanghai, China; and the 3Department of Psychiatry, The Center for Studies of Addiction, University of Pennsylvania School of Medicine, Philadelphia, PA.
ABSTRACT
Alcohol consumption accelerates liver damage and diminishes the anti-hepatitis C virus (HCV) effect of interferon alfa (IFN-) in patients with HCV infection. It
is unknown, however, whether alcohol enhances HCV replication and promotes HCV disease progression. The availability of the HCV replicon containing
hepatic cells has provided a unique opportunity to investigate the interaction between alcohol and HCV replicon expression. We determined whether alcohol
enhances HCV RNA expression in the replicon containing hepatic cells. Alcohol, in a concentration-dependent fashion, significantly increased HCV replicon
expression. Alcohol also compromised the anti-HCV effect of IFN-. Investigation of the mechanism(s) responsible for the alcohol action on HCV replicon
indicated that alcohol activated nuclear factor B (NF-B) promoter. Caffeic acid phenethyl ester (CAPE), a specific inhibitor of the activation of NF-B,
abolished alcohol-induced HCV RNA expression. In addition, naltrexone, an opiate receptor antagonist, abrogated the enhancing effect of alcohol on HCV
replicon expression. In conclusion, alcohol, probably through the activation of NF-B and the endogenous opioid system, enhances HCV replicon expression
and compromises the anti-HCV effect of IFN-. Thus, alcohol may play an important role in vivo as a cofactor in HCV disease progression and compromise
IFN--based therapy against HCV infection.
BACKGROUND
Hepatitis C virus (HCV) is responsible for the vast majority of cases of transfusion-associated and community-acquired non-A, non-B hepatitis and infects an estimated 170 million people worldwide. The seroprevalence of anti-HCV antibody in the United States has been estimated at 1.8%, which corresponds to approximately 4 million people. HCV is the leading cause of chronic viral hepatitis in the United States, and HCV-infected individuals are the major recipients of liver transplantation. HCV, first molecularly cloned in 1989,1 is a positive-strand RNA virus of the flavivirus family with a genome size of ~10 kb, which encodes a number of structural (core, E1, E2, and p7) and nonstructural (NS2, NS3, NS4A, NS4B, NS5A and NS5B) proteins. HCV has at least 6 distinct but related genotypes with more than 50 subtypes, and genotype 1 is the most common in the United States, Europe, and most parts of Asia. HCV typically escapes clearance by the host's immune system and leads to the establishment of a persistent infection in approximately 70% of infected individuals. The consequences of a subset of patients with chronic HCV infection are cirrhosis, liver failure, and hepatocellular carcinoma. Treatment of HCV with interferon alfa (IFN-) and ribavirin is associated with a sustained response rate of less than 50%. These limited therapeutic efficacies and the absence of an effective HCV vaccine underscore the importance of research on factors that enhance HCV infection and compromise IFN--based therapy.
Alcohol is the most commonly used and abused drug in the United States. Alcohol abuse significantly affects morbidity and mortality from infectious diseases. Alcohol consumption accelerates liver damage, diminishes therapeutic response to IFN-, and increases the rate of hepatocellular carcinoma in patients with chronic HCV infection. Alcohol added in vivo and in vitro also impairs liver parenchymal cells and various functions of immune cells, including monocytes, T cells, and natural killer cells, which contribute to hepatocyte damage in chronic HCV infection. Alcohol consumption and viral hepatitis infection, both recognized as major causes of liver disease worldwide, frequently coexist in patients with chronic liver disease. Alcohol and HCV most likely act synergistically to promote the development and progression of liver damage. There is little direct information available concerning the effects of alcohol abuse on HCV replication in hepatic cells. This lack of knowledge about the impact of alcohol abuse on HCV is a major barrier to fundamental understanding of HCV-related morbidity and mortality in alcohol abusers with HCV infection. Thus, it is critical to investigate the impact of alcohol abuse on HCV replication in the target cells such as hepatic cells. We investigated whether alcohol enhances HCV RNA expression in HCV replicon containing cell lines. We also studied whether the in vitro addition of alcohol to these cells compromises the anti-HCV effect of IFN-.
Discussion by authors
Alcohol abuse is a major cofactor in the development of HCV associated liver disease. Chronic alcohol abuse mediates liver damage as a result of increase in
production of proinflammatory cytokines. In the setting of chronic HCV infection, alcohol ingestion has an additional effect of diminishing immune clearance and increasing viral burden to hasten the onset of cirrhosis and hepatocellular carcinoma. Serum HCV RNA levels were significantly higher in habitual alcohol drinkers with chronic HCV infection than in infrequent alcohol drinkers with chronic HCV. HCV RNA levels were significantly higher in alcohol drinkers than abstainers, and the number of responders in IFN therapy decreased as alcohol intake increased. These in vivo data strongly support the hypothesis that alcohol plays a role as a cofactor in promoting HCV RNA expression.
Clinical trials indicate a therapeutic benefit of IFN- treatment in chronic HCV infection.13,18 Currently available combination therapy with IFN- and ribavirin is, however, effective in less than 50% of treated subjects. Although a history of alcohol abuse is not a contraindication to clinical therapy, continued alcohol use during therapy adversely affects response to HCV treatment. Heavy alcohol consumption reduces the efficacy of IFN- therapy for chronic HCV infection, and this adverse effect of alcohol drinking on efficacy might be reversed, partly, by abstinence for a long period before treatments. Thus, it is important to identify whether alcohol is one of the cofactors that are responsible for the failure of IFN- treatment. The HCV replicon system has been successfully used to examine the anti-HCV effect of IFN-. IFN- inhibits HCV RNA expression in Huh.8 cells, as shown by a declined HCV RNA expression over time. Our data showing that IFN- significantly inhibited (up to 90%) HCV RNA expression in Huh.8 cells further confirms this observation. Thus, the Huh.8 cell line is an excellent in vitro model for studying whether alcohol interferes with the anti-HCV effect of IFN- on HCV RNA expression. We hypothesized that alcohol abuse may have a negative impact on the anti-HCV effect of IFN-. Our data support this hypothesis, showing that alcohol compromised the anti-HCV effect of IFN- in Huh.8 cells. This finding suggests the possibility that alcohol may reduce efficacy of IFN- therapy in vivo. The mechanism(s) responsible for the IFNÑmediated therapeutic effect remain unclear. Thus, further studies are critical to determine the mechanism(s) responsible for the anti-HCV ability of IFN- and whether alcohol has the ability to interfere with the mechanism(s) involved in IFN- action against HCV.
Moderate alcohol consumption increases oxidative stress in patients with chronic hepatitis C
Hepatology July 2003, Volume 38, Number
Cristina Rigamonti. Internal Medicine Unit, Ospedale Maggiore della Caritˆ, Novara, Italy
"...the data presented are the first evidence that even moderate alcohol consumption worsens oxidative stress in patients with chronic hepatitis C and
suggest that oxidative injury might be one of the mechanisms by which alcohol contributes to the progression of chronic hepatitis CÉ.."
It is well established that, in about 20% to 25% of the patients with chronic hepatitis C, the disease will progress to cirrhosis or even to hepatocellular carcinoma within 20 years from infection.1 Among the factors that contribute to the evolution of hepatitis C, the role of alcohol consumption has received increasing attention (for review, see Vento and Cainelli and Peters and Terrault). An alcohol intake exceeding 40 g/d for women and 60 g/d for men increases by 2- to 3-fold the risk of developing cirrhosis, independently from the duration of HCV infection. According to Corrao and Aric˜, the interaction between ethanol and hepatitis C virus (HCV) in promoting cirrhosis is additive for lifetime daily alcohol intake of 50 g/d but becomes synergistic when alcohol consumption exceeds 125 g/d. Nonetheless, a recent report suggests that even moderate alcohol intake (below 30-40 g/d) can promote the progression of fibrosis in patients with HCV infection. In addition, heavy alcohol consumption has also an additive effect with chronic hepatitis C in increasing the risk of hepatocellular carcinoma.
Despite the finding that the capacity of ethanol to worsen the evolution of HCV infection is well documented, the mechanisms involved are still poorly understood. It has been proposed that alcohol might favor viral replication8; however, other mechanisms are also likely to be involved. Recent studies have documented an association between HCV infection and the presence of both liver and serum markers of oxidative stress. Furthermore, the expression of HCV core protein in transgenic mice or in hepatoma cells lines alters the liver antioxidant status and promotes lipid peroxidation. Ethanol is also known to stimulate the production of reactive oxygen species and hydroxyethyl free radicals and to lower hepatic antioxidant defense. The implication of oxidative damage in human alcohol liver injury is supported by several reports showing an increase in lipid peroxidation markers in patients with alcoholic liver disease. Furthermore, immunohistochemistry has shown the presence of lipid peroxidation products in the areas of liver fatty infiltration, focal necrosis, and fibrosis.
These observations prompted us to investigate whether ethanol intake might potentiate oxidative stress in patients with chronic hepatitis C. One of the problems encountered in performing retrospective investigations with serum samples stored frozen for several years is that autooxidation can affect the direct measurement of lipid peroxidation. In the present study, we took advantage of the immunogenic properties of proteins complexed with lipid peroxidation products to evaluate the presence of antibodies against lipid peroxidation-derived antigens as markers of oxidative stress. Indeed, recent studies have shown that the titers of circulating IgG against epitopes derived from the binding of lipid peroxidation products to human albumin or low-density lipoproteins are significantly increased in patients with alcoholic liver disease. Moreover, alcoholic patients also display a significant increase in antibodies that recognize oxidized cardiolipin (Ox-CL).
ABSTRACT
The mechanisms by which alcohol consumption worsens the evolution of chronic hepatitis C (CHC) are poorly understood. We have investigated the possible interaction between hepatitis C virus (HCV) and ethanol in promoting oxidative stress. Circulating IgG against human serum albumin (HSA) adducted with malondialdehyde (MDA-HSA), 4-hydroxynonenal (HNE-HSA), or arachidonic acid hydroperoxide (AAHP-HSA) and against oxidized cardiolipin (Ox-CL) were
evaluated as markers of oxidative stress in 145 CHC patients with different alcohol consumption, 20 HCV-free heavy drinkers (HD) without liver disease, and 50 healthy controls. Anti-MDA IgG was increased in CHC patients irrespective of alcohol intake as well as in the HD group. CHC patients with moderate alcohol intake (<50 g ethanol/d), but not HD, also had significantly higher values of anti-AAHP-HSA, anti-HNE-HSA, and anti-Ox-CL IgG (P < .05) than controls. A further elevation (P < .001) of these antibodies was evident in CHC patients with heavy alcohol intake (>50 g ethanol/d). Anti-AAHP and anti-Ox-CL IgG above the 95th percentile in the controls were observed in 24% to 26% of moderate and 58% to 63% of heavy drinkers but only in 6% to 9% of the abstainers. The risk of developing oxidative stress during CHC was increased 3-fold by moderate and 13- to 24-fold by heavy alcohol consumption. Heavy drinking CHC patients had significantly more piecemeal necrosis and fibrosis than abstainers. Diffuse piecemeal necrosis was 4-fold more frequent among alcohol-consuming patients with lipid peroxidation-related antibodies than among those without these antibodies. In conclusion, even moderate alcohol consumption promotes oxidative stress in CHC patients, suggesting a role for oxidative injury in the worsening of CHC evolution by alcohol.
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