Treatment of hepatitis C infection

Hepatitis C virus-mediated inhibition of cathepsin S increases invariant-chain expression on hepatocyte surface

Hepatocytes are the main source of hepatitis C virus (HCV) replication and contain the maximum viral load in an infected person. Chronic HCV infection is characterized by weak cellular immune responses to viral proteins. Cathepsin S is a lysosomal cysteine protease and controls HLA-DR-antigen complex presentation through the degradation of the invariant chain. In this study, we examined the effect of HCV proteins on cathepsin S expression and found it to be markedly decreased in dendritic cells (DCs) exposed to HCV or in hepatocytes expressing HCV proteins. The downregulation of cathepsin S was mediated by HCV core and NS5A proteins involving inhibition of the transcription factors interferon regulatory factor 1 (IRF-1) and upstream stimulatory factor 1 (USF-1) in gamma interferon (IFN-γ)-treated hepatocytes. Inhibition of cathepsin S by HCV proteins increased cell surface expression of the invariant chain. In addition, hepatocytes stably transfected with HCV core or NS5A inhibited HLA-DR expression. Together, these results suggested that HCV has an inhibitory role on cathepsin S-mediated major histocompatibility complex (MHC) class II maturation, which may contribute to weak immunogenicity of viral antigens in chronically infected humans.

Naringenin inhibits the assembly and long-term production of infectious hepatitis C virus particles through a PPAR-mediated mechanism

BACKGROUND & AIMS

Hepatitis C virus (HCV) infection affects 3% of the world population and is the leading cause of chronic liver disease worldwide. Current standard of care is effective in only 50% of the patients, poorly tolerated, and associated with significant side effects and viral resistance. Recently, our group and others demonstrated that the HCV lifecycle is critically dependent on host lipid metabolism and that its production is metabolically modulated.

METHODS

The JFH1/Huh7.5.1 full lifecycle model of HCV was used to study the antiviral effects of naringenin on viral replication, assembly, and production. Activation of PPARα was elucidated using GAL4-PPARα fusion reporters, PPRE reporters, qRT-PCR, and metabolic studies. Metabolic results were confirmed in primary human hepatocytes.

RESULTS

We demonstrate that the grapefruit flavonoid naringenin dose-dependently inhibits HCV production without affecting intracellular levels of the viral RNA or protein. We show that naringenin blocks the assembly of intracellular infectious viral particles, upstream of viral egress. This antiviral effect is mediated in part by the activation of PPARα, leading to a decrease in VLDL production without causing hepatic lipid accumulation in Huh7.5.1 cells and primary human hepatocytes. Long-term treatment with naringenin leads to a rapid 1.4 log reduction in HCV, similar to 1000U of interferon. During the washout period, HCV levels returned to normal, consistent with our proposed mechanism of action.

CONCLUSIONS

The data demonstrates that naringenin is a non-toxic assembly inhibitor of HCV and that other PPARα agonists play a similar role in blocking viral production. The combination of naringenin with STAT-C agents could potentially bring a rapid reduction in HCV levels during the early treatment phase, an outcome associated with sustained virological response.

Pilot Results: Pre-Treatment with Deferasirox Increases the Chances of Rapid Viral Response in Patients with Chronic Hepatitis C Infection Treated with PEG-Interferon/Ribavirin

Chronic hepatitis C infection [CHCV] is a major cause of morbidity and mortality. It is treated with a combination of interferon and ribavirin [INF/RIBV] for 1 year in strain 1 & 4 prevalent in our geographic area 1. Iron overload is an important cofactor of disease outcome, enhancing inflammation, fibrosis and cirrhosis and predisposing to hepatocellular carcinoma. It also affects the response to conventional therapy2–3. We evaluated the impact of pre-treatment iron chelation using deferasirox on the outcome of combination therapy (160μg PEG-Interferon α-2-a (Reiferon-Retard) and ribavirin) in terms of early viral response defined as clearance or 2 log reduction in viral load at 12 weeks and rapid viral response defined as viral clearance by four weeks. The latter may imply a shortened duration of therapy to 6 months rather than a year, improving cost effectiveness and reducing side effects 4,5. The study included 30 patients with CHCV candidates for INF/RIBV therapy with a Metavir score of less than F3 by liver biopsy or fibrotest. The mean serum ferritin of patients prior to therapy was 520+/−98 ng/ml. Ten patients were subjected to iron chelation using deferasirox (15mg/Kg/day p.o.) for 6–8 weeks prior initiation of therapy (group I), bringing their serum ferritin to 309+/−74 ng/ml, whereas 20 patients started therapy without pre-treatment chelation (group II). Patients were followed up periodically both clinically and laboratory. HCV PCR both quantitative and qualitative were conducted at week 4 and 12. In 7 patients (70%) from group I, early viral clearance at 12 weeks, was reported compared to 12 (60%) in group II (p>0.05). Six patients out of the 7 cleared in group I and 6 patients out of the 12 in group II (p<0.01) had a rapid virologic response with complete viral clearance at 4 weeks. Pre-treatment with deferasirox may improve early viral response rates. It seems to favor rapid virologic response in CHCV patients treated with INF/RIBV with a potential shorter duration of therapy, significant cost reduction and less side effects. Larger studies are needed to confirm the results of this pilot work.

Controversies in and challenges to our understanding of hepatitis C

Discovered in 1989, the hepatitis C virus (HCV) continues to cause significant morbidity and mortality world-wide despite a huge research commitment to defining and understanding the virus and the disease it causes. This paper discusses a number of areas where progress in the management of the HCV have not kept pace with the scientific understanding of the HCV. It is suggested that in the fields of HCV prevention and providing access to treatment, practice falls short of what could be achieved. The role of alcohol in the pathogenesis of HCV liver injury is discussed. Discrimination against those with HCV infection and particularly those in prison settings fails to match good clinical practice. The complicated processes of sharing information between specialty groups is also discussed in an attempt to optimise knowledge dissemination in this field.

Article Commentary: Occupational Risks of Blood Exposure in the Operating Room

Bloodborne pathogens continue to be a source of occupational infection for healthcare workers, but particularly for surgeons. Over 1 per cent of the U.S. population has one or more chronic viral infections. Hepatitis B is the infection that has the longest known role as an occupational pathogen, but infection with this virus is largely preventable with the use of the effective hepatitis B vaccine. Hepatitis C affects the largest number of people in the United States, and there is no vaccine available for the prevention of this infection. HIV infection still has not been associated with a documented transmission in the operating room environment, but six cases of probable occupational transmission have been reported. A total of 57 healthcare workers have had documented occupational infection since the epidemic of HIV infection began. Infection of blood-borne pathogens to patients from infected surgeons remains a concern. Surgeons who are e-antigen-positive for hepatitis B have been well documented to be an infection risk to patients in the operating room. Only four surgeons have been documented to transmit hepatitis C, although other transmissions have occurred in the care of patients when practices of infection control have been violated. No surgical transmission of HIV to a patient has been identified at this time. Prevention of occupational infection requires use of protective barriers, avoidance of exposure risk by modification of techniques, and a constant awareness of sharp instruments in the operating room. Blood exposure in the operating room carries risk of infection and should be avoided. It is likely that other infectious agents will emerge as operating room threats. Surgeons must maintain vigilance in avoiding blood exposure and percutaneous injury.

Improving access to HCV treatment: external jugular venepuncture can overcome problems with difficult venous access

Many patients requiring antiviral treatment of chronic hepatitis C (HCV) have a background of significant injection drug use (IDU). In a proportion of patients, IDU results in difficulty with blood collection from conventional sites. We audited patients from the Liver Clinics and Drug Health Pharmacotherapy Service of The Royal Prince Alfred Hospital (RPAH) to determine the incidence of difficulty with blood collection. This survey identified the need for an innovative venous access strategy to better manage this group of patients. An external jugular venepuncture (EJV) protocol and education package was developed in collaboration with the Department of Anaesthetics, Gastroenterology and Liver Centre and HCV clinical nurse consultants (CNC). RPAH policy and procedure committee approved the protocol and patient information sheet. Patients with a history of difficulty with blood collection were eligible for the protocol. Patient satisfaction surveys were conducted. The initial survey of patients from the liver clinics and pharmacotherapy service identified that 48 percent had difficulty with blood collection from conventional sites. In the period October 2002 to July 2006, 29 patients (89 percent with history of IDU) were referred for EJV assessment. Major indications for EJV were for blood testing for initiation and monitoring of antiviral therapy and ongoing assessment of HCV infected patients. No adverse events resulted from the procedure. All patients surveyed report high levels of satisfaction with the technique compared to previous venous access attempts. EJV improves access to antiviral therapy and is a safe and effective technique for patients with difficult venous access (DVA). In addition, we have utilised EJV for post-transplant care of patients and used external jugular vein cannulation as vascular access for contrast imaging in hepatocellular carcinoma (HCC) assessment.