Hepatitis C and alcohol: interactions, outcomes, and implications

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.

Injection drug use and the hepatitis C virus: considerations for a targeted treatment approach--the case study of Canada

Infection with the hepatitis C virus (HCV) is a major public health burden in Canada and globally. The literature shows that injection drug use is currently the primary transmission route for HCV, and that a majority of injection drug users (IDUs) are currently infected with HCV in Canada. This article first reviews the burden of HCV within IDU populations and the transmission risks and the treatment implications specific to IDUs. Traditionally, IDUs have been excluded from HCV treatment unless abstaining from illicit drug use. However, recent research suggests that categorical exclusion is not medically necessary. A series of key questions about the feasibility of offering HCV treatment to IDUs in the specific Canadian context are considered, including concerns related to the motivation of treatment for IDUs, treatment delivery, treatment side effects, HCV reinfection, and the social environment. The article concludes that treatment of HCV-infected illicit drug users is both feasible and may be necessary to reduce transmission and adverse outcomes in this high-risk population.

Chronic alcohol consumption accelerates liver injury in T cell-mediated hepatitis: alcohol disregulation of NF-kappaB and STAT3 signaling pathways

Alcohol consumption is a major risk factor accelerating the progression of liver disease in patients with chronic hepatitis virus infection. However, the mechanism underlying the enhanced susceptibility of alcoholics to liver injury is not fully understood. Here, we demonstrate that chronic ethanol consumption increases the susceptibility of C57BL/6 mice to concanavalin A (Con A)-induced T cell-mediated hepatitis. Injection of a low dose of Con A (5 microg/g) causes severe liver damage in ethanol-fed mice as evidenced by a significant elevation of serum alanine aminotransaminase levels, massive necrosis, and infiltration of leukocytes but only slightly induces liver injury in control pair-fed mice. In ethanol-fed mice, the activation and cytotoxicity of natural killer T cells, cells that play key roles in Con A-induced T cell hepatitis, are not significantly enhanced relative to pair-fed mice. Moreover, Con A-induced activation of hepatic NF-kappaB is increased, whereas activation of STAT1 and STAT3 is attenuated in ethanol-fed mice. Consistent with this result, the expression of chemokines and adhesion molecules [such as ICAM-1, macrophage inflammatory protein (MIP)-1, MIP-2, and MCP-1] controlled by NF-kappaB is upregulated, whereas STAT1-controlled expression of chemokines (such as MIG and IP-10) is downregulated in ethanol-fed mice compared with pair-fed mice. In conclusion, chronic alcohol consumption accelerates T cell-mediated hepatitis via upregulation of the NF-kappaB signaling pathway and subsequently enhances expression of chemokines/adhesive molecules and recruitment of leukocytes into the liver. Downregulation of the antiapoptotic STAT3 signal may also contribute to alcohol potentiation of T cell hepatitis.

Inhibition of antigen-presenting cell functions by alcohol: implications for hepatitis C virus infection

The mechanisms of alcohol-induced immunosuppression include defects in innate and adaptive immune responses. Monocytes and dendritic cells (DCs) link innate and adaptive immune responses as they recognize viral antigens and induce antigen-specific T-cell activation. We investigated the effects of alcohol on antigen-presenting cell functions. Acute alcohol consumption by healthy volunteers (vodka, 2 ml/kg) resulted in significantly reduced antigen-presenting cell function of monocyte-derived DCs. Reduced allostimulatory capacity of DCs treated with alcohol in vitro correlated with decreased co-stimulatory molecule (B7.1 and B7.2) expression, as well as with reduced interleukin (IL)-12 and increased IL-10 concentrations, in mixed lymphocyte cultures. Dendritic cells recognize viral antigens in hepatitis C virus (HCV) infection, and HCV disease is accelerated in alcohol-dependent individuals. For patients with chronic HCV infection, we found reduced allostimulatory capacity of myeloid DCs. Furthermore, DC function was reduced by in vitro alcohol treatment of DCs obtained from HCV-infected patients, supporting the suggestion that viral factors and alcohol may interact to doubly suppress DC functions. We found that induction of maturation with lipopolysaccharide could not fully ameliorate the reduced DC allostimulatory capacity caused by alcohol treatment, HCV infection, or their combination. In addition, soluble factors in the supernatants obtained from mixed lymphocyte cultures containing alcohol-treated DCs or DCs obtained from HCV-infected patients could transfer inhibition of T-cell proliferation in cultures containing DCs obtained from healthy volunteers. Anti-IL-10 neutralizing antibody ameliorated the reduced mixed lymphocyte reaction containing DCs obtained from HCV-infected patients, whereas exogenous IL-12, but not anti-IL-10, treatment ameliorated the reduced T-cell proliferation induced by alcohol treatment of DCs obtained from healthy volunteers. Our results support the suggestion that both acute alcohol intake and in vitro alcohol treatment inhibit DC antigen-presenting cell function and support the hypothesis that viral factors interact with alcohol to reduce DC functions in HCV infection.

Hyperhomocysteinemia, endoplasmic reticulum stress, and alcoholic liver injury

Deficiencies in vitamins or other factors (B6, B12, folic acid, betaine) and genetic disorders for the metabolism of the non-protein amino acid-homocysteine (Hcy) lead to hyperhomocysteinemia (HHcy). HHcy is an integral component of several disorders including cardiovascular disease, neurodegeneration, diabetes and alcoholic liver disease. HHcy unleashes mediators of inflammation such as NFkappaB, IL-1beta, IL-6, and IL-8, increases production of intracellular superoxide anion causing oxidative stress and reducing intracellular level of nitric oxide (NO), and induces endoplasmic reticulum (ER) stress which can explain many processes of Hcy-promoted cell injury such as apoptosis, fat accumulation, and inflammation. Animal models have played an important role in determining the biological effects of HHcy. ER stress may also be involved in other liver diseases such as alpha (1)-antitrypsin (alpha(1)-AT) deficiency and hepatitis C and/or B virus infection. Future research should evaluate the possible potentiative effects of alcohol and hepatic virus infection on ER stress-induced liver injury, study potentially beneficial effects of lowering Hcy and preventing ER stress in alcoholic humans, and examine polymorphism of Hcy metabolizing enzymes as potential risk-factors for the development of HHcy and liver disease.

Host factors and failure of interferon-alpha treatment in hepatitis C virus

Failure of interferon-alpha (IFN-alpha) treatment in patients with chronic hepatitis C virus (HCV) infection is a challenging obstacle for clinical and experimental hepatology. Both viral and host factors have been implicated in reducing responsiveness to IFN-alpha therapy. The role of viral factors has been studied extensively and has been summarized in several review articles; however, much less attention has been paid to host factors. In this paper, we review evidence of host factor involvement in IFN-alpha treatment failure. We discuss possible underlying mechanisms responsible for these effects. Potential therapeutic strategies to enhance the effectiveness of IFN-alpha therapy for HCV are also proposed.