Hepatitis C: the clinical spectrum of the disease

Post-translational modification of the hepatitis C virus core protein by tissue transglutaminase

The hepatitis C virus (HCV) core protein is a structural protein that packages the viral genomic RNA. In this study, we demonstrate that a stable core protein dimer could be produced in liver cells. The production of this protein could be enhanced by calphostin C and serum deprivation. This protein was determined to be the core protein dimer because of its reactivity with the anti-core antibody, its similar electrophoretic mobility compared with that of the core protein dimer generated by cross-linking with glutaraldehyde, and its increase in size by a hemagglutinin tag fused to the core protein sequence. This core protein dimer was highly stable and resistant to SDS and beta-mercaptoethanol. The enzyme that mediated the formation of this stable core protein dimer was determined to be the tissue transglutaminase (tTG) because, first, tTG could be activated by calphostin C and serum deprivation; second, the formation of this dimer was suppressed by monodansylcadaverine, a tTG inhibitor; and third, the core protein could be cross-linked by tTG in vitro. Thus, the HCV core protein represents the first known viral structural protein substrate of tTG. The post-translational modification by tTG reduced the RNA binding activity of the core protein, raising the possibility that tTG may regulate the biological functions of the HCV core protein.

Inhibition of matrix metalloproteinases blocks lethal hepatitis and apoptosis induced by tumor necrosis factor and allows safe antitumor therapy

Acute and fulminant liver failure induced by viral hepatitis, alcohol or other hepatotoxic drugs, are associated with tumor necrosis factor (TNF) production. In a mouse model of lethal hepatitis induced by TNF, apoptosis and necrosis of hepatocytes, but also lethality, hypothermia and influx of leukocytes into the liver, are prevented by a broad-spectrum matrix metalloproteinase (MMP) inhibitor, BB-94. Mice deficient in MMP-2, MMP-3 or MMP-9 had lower levels of apoptosis and necrosis of hepatocytes, and better survival. We found induction of MMP-9 activity and fibronectin degradation. Our findings suggest that several MMPs play a critical role in acute, fulminant hepatitis by degrading the extracellular matrix and allowing massive leukocyte influx in the liver. BB-94 also prevented lethality in TNF/interferon-gamma therapy in tumor-bearing mice. A broad-spectrum MMP inhibitor may be potentially useful for the treatment of patients with acute and perhaps chronic liver failure, and in cancer therapies using inflammatory cytokines.

Impairment of metabolic function in chronic hepatitis C is related to factors associated with resistance to therapy

OBJECTIVE

Liver disease causes a loss of hepatic function, and remission is associated with improved functional hepatic mass. The object of the present study was to investigate whether liver metabolic function assessed by antipyrine clearance is related to other disease characteristics influencing response to therapy in chronic hepatitis C.

METHODS

Patients (n = 96) received three different treatment regimens: one group received interferon alfa-2b for 48 wk; in a second group with maintained positive hepatitis C virus (HCV) RNA after 12 wk, interferon was combined for 36 wk with oral ribavirin; and patients who were relapsers or nonresponders to a previous therapy with interferon alone received interferon alfa-2b plus ribavirin for 48 wk.

RESULTS

Twenty-five patients (26%) showed sustained normalization of ALT levels and negative HCV RNA 6 months after therapy. The response was more likely to be sustained in patients with a genotype other than 1 (52.0% vs 15.5% in patients with genotype 1, p < 0.001), and the percentage of sustained responders was higher among patients who demonstrated negativity of HCV RNA at the end of 4 wk of treatment (64% vs 13% without negativity, p < 0.001). Sustained response was associated with significantly lower baseline serum ferritin (-46%, p < 0.01) and duration of infection (-33%, p < 0.01). Baseline antipyrine clearance was higher in sustained responders than in nonresponders (+19%, p < 0.05) and lower in genotype 1 patients than in those with a genotype other than 1 (-24%, p < 0.05). Antipyrine clearance increased by 12% at the end of the 48-wk course of treatment among sustained responders (+34% vs nonresponders, p < 0.001) and still remained elevated at the end of the follow-up (+35% vs nonresponders, p < 0.001).

CONCLUSION

In summary, the present study shows that liver oxidative metabolism is related to antiviral response rates and suggests that much of the effect is explained by viral genotype.

Insights into the epidemiology, natural history and pathogenesis of hepatitis C virus infection from studies of infected donors and blood product recipients

Studies of patients with post-transfusion non-A, non-B hepatitis and their implicated donors were critical to the discovery of hepatitis C virus (HCV) and to the development and progressive enhancement of HCV immunoassays for donor screening and diagnostic applications. Post-transfusion HCV cases have also been used to define the time course of viral and immunological markers following acute infection. Even more precise data on the timing and characteristics of viremia and immune responses during primary HCV infection have been derived from studies of serial samples from source plasma donors who were identified while in the process of infection and seroconversion. Such data have been critical to the derivation of estimates for the viremic, pre-seroconversion window period, and hence projections of the yield of addition of nucleic acid amplification technology (NAT) or HCV core antigen enzyme immunoassays (Ag-EIAs) to antibody screening in donor and diagnostic settings. In addition to these implications for screening and diagnosis, studies of HCV in the blood donor and blood product recipient settings have yielded substantial insights into the epidemiology, pathogenesis and prognosis of HCV infection. In the future, prospective studies of blood and plasma donors detected in the primary phase of HCV infection by NAT screening, will be important for defining viral and host genetic and immunological determinants of clearance of acute viremia, as well as for investigating the benefits of early treatment. Thus, the findings from studies of HCV among donors and blood product recipients have yielded and should continue to provide important insights into HCV pathogenesis leading to novel diagnostic, therapeutic and vaccination strategies.

Doppler sonography measurement of portal blood flow velocity after glucagon injection in patients with chronic HCV infection

Doppler sonography measurement of portal flow velocity (PFV) after glucagon injection was performed in 45 patients with chronic hepatitis C virus (HCV) infection. Patients were divided into three groups: group 1 = no or mild liver fibrosis; group 2 = moderate to severe liver fibrosis, and group 3 = liver cirrhosis. All patients were examined using a Doppler ultrasound (US) multipurpose equipment and a convex 3.5-MHz probe, 10 min before (baseline), as well as 5 and 10 min after, IV administration of 1 mg of glucagon chloride. No significant differences were found in mean baseline PFV among group 1 (19.4 +/- 2.4 cm/s), group 2 (20.1 +/- 3.6 cm/s) and group 3 (17.5 +/- 3.7 cm/s). Five minutes after glucagon injection, all three groups showed significantly increased values of mean PFV (25.6 +/- 4.8, 23.7 +/- 4.0 and 19.5 +/- 5.0 cm/s, respectively; p < 0.05 vs. baseline). The mean increase of PFV above baseline was significantly higher in group 1 (7.9 +/- 3.7 cm/s) than in group 2 (4.5 +/- 3.9 cm/s) (p < 0.05) or in group 3 (2.7 +/- 2.3 cm/s) (p < 0.05). A significant inverse correlation was found between individual values of fibrosis score and of individual increase of PFV. In patients with chronic HCV infection, Doppler sonography measurement of PFV after glucagon injection could be useful in assessing the severity of liver histological damage.

Nested restriction site-specific PCR to detect and type hepatitis C virus (HCV): a rapid method to distinguish HCV subtype 1b from other genotypes

Genotypic differentiation of hepatitis C virus (HCV) has become an integral part of clinical management and epidemiologic studies of hepatitis C infections. Thus, it is extremely important in areas such as the Czech Republic, where current instrumentation and kits for assessing HCV infection are too costly for widespread use. We describe a new and relatively inexpensive method called nested restriction site-specific PCR (RSS-PCR) that generates a "fingerprint" pattern to represent an HCV genotype without the use of restriction endonucleases and that specifically differentiates HCV genotype 1b from the other HCV genotypes. The RSS-PCR method was applied directly to serum samples from patients with hepatitis C from the Czech Republic and from patients with known HCV genotypes from the United States. The method was validated by comparison of the subtype determined by RSS-PCR to the subtype determined from analysis of the 5' noncoding region (NC) or the nonstructural protein gene (NS5b) nucleotide sequence of HCV in these clinical samples. From 75 Czech samples containing HCV RNA, three distinct RSS-PCR patterns were observed; 54 were predicted to contain subtype 1b, 19 were predicted to contain subtype 1a, and 2 were predicted to contain subtype 3a. Among 54 samples predicted to contain HCV genotype 1b, all were confirmed by their 5' NC or NS5b sequences to be subtype 1b. Thus, both the sensitivity and specificity of the RSS-PCR test for the differentiation of HCV subtype 1b from the others were 100%. While the assay described here was designed to specifically differentiate HCV subtype 1b from the other HCV genotypes, the RSS-PCR method can be modified to differentiate any HCV genotype or subtype of interest. Its simplicity and speed may provide new opportunities to study the epidemiology of HCV infections and the relationship between HCV genotypes and clinical outcome by more laboratories throughout the world.

Current and future therapies of hepatitis C

With recent advances in the treatment of chronic hepatitis C, patients with elevated aminotransferase levels, detectable HCV RNA in the serum, and chronic inflammation are candidates for therapy. The best initial therapy is interferon plus ribavirin, achieving a sustained response rate in 40% of patients. The duration of therapy should be based on HCV genotype (48 weeks for genotype 1; 24 weeks for other genotypes). Serum HCV RNA should be measured at week 24 to assess response and guide further therapy in patients with genotype 1 infection. Patients unsuitable for combination therapy can be treated with interferon monotherapy. Side effects, dose modification and discontinuation are generally more frequent with interferon plus ribavirin, but can be managed with close follow-up and careful monitoring. With rapid developments in treatment, new therapies will require careful prospective evaluation according to HCV genotype and viral-load characteristics. Recommendations for therapy will probably change every few years, and novel approaches may provide effective therapy for most patients with hepatitis C.

Tumors are unique organs defined by abnormal signaling and context

Many cancer investigations have focussed on the eradication of the cancer cell itself and in doing so, overlook the inherent complexity and heterogeneity of solid tumors. Here, we argue that, in many cases, it is the altered communication within the tumor, rather than mutations per se, that is the defining characteristic of cancer. As a result, tumorigenesis can be indirectly initiated by environmental or inherited factors that affect the stromal cells. We propose that anticancer research might be more effective if aimed at eradicating the cause of abnormality rather than just treating the end result.

[Hepatitis C]

It has been estimated that 3% of the world population is infected with the hepatitis C virus. Those who are blood product recipients or have been illicit drug users are at risk. Dental and medical procedures as well as tattooing and acupuncture are also risk factors. Chronic infection occurs in up to 85% of infected cases but they may remain without symptoms during years or even decades, and clinical presentation varies. Determination of anti-HCV in sera is a fairly sensitive tool for the diagnosis, and confirmation requires the identification of HCV-RNA. Staging of the liver disease as well as definition of its present activity can be graded by liver biopsy. The aim of treatment is to stop the progression of the hepatic disease by inhibiting viral replication. Due to the low therapeutic efficacy combined with important side-effects, the administration of interferon and ribavirin have specific indications and contraindications. Predictive factors of therapeutic response, particularly viral load and genotypes of HCV, are useful in the evaluation of patients.

Unfavourable effects of colchicine in combination with interferon-alpha in the treatment of chronic hepatitis C

BACKGROUND

The prognosis of chronic hepatitis depends on the progression of hepatic fibrosis.

AIM

To investigate whether the antifibrotic drug colchicine, in combination with interferon-alpha has a role in the treatment of chronic hepatitis C.

METHODS

Sixty-five HCV-RNA positive patients with chronic hepatitis were randomized to receive interferon-alpha, 6 MU t.i.w. for 6 months followed by 3 MU t.i.w. for further 6 months, with or without the adjunct of colchicine, 1 mg o.d., 6 days a week, for 3 years. We report an interim analysis after the first 18 months.

RESULTS

Thirty-four patients received interferon-alpha and 31 received interferon-alpha and colchicine. The two groups were comparable for baseline data, including HCV-RNA levels, genotypes and histological grading/staging. Drop-outs and side-effects were similar. The proportion of patients who achieved alanine transaminase normalization or undetectable HCV-RNA at month 6 was higher in the interferon-alpha (68% and 47%, respectively) than in the interferon-alpha plus colchicine group (32% and 23%, P=0.004 and P=0. 04, respectively). End-of-treatment biochemical and virological response occurred in 41% and 29% of the interferon-alpha and 19% and 10% of the combination group, respectively (P=0.05 and P=0.05). Sustained biochemical response occurred in 26% of the interferon-alpha and 6% of the interferon-alpha plus colchicine group (P=0.03), corresponding percentages of sustained HCV-RNA loss being 21% and 3% (P=0.04).

CONCLUSIONS

The combination of colchicine and interferon-alpha worsens the effectiveness of interferon-alpha alone in HCV chronic hepatitis. These alarming findings prompted us to interrupt the trial at this stage.

Pathogenesis, diagnosis and management of hepatitis C

The hepatitis C virus (HCV) is the leading cause of chronic liver disease worldwide. It is estimated that about 170 million people are chronically infected with HCV. Chronic hepatitis C is a major cause of cirrhosis and hepatocellular carcinoma and HCV-related end-stage liver disease is, in many countries, the first cause of liver transplantation. HCV infection is characterized by its propensity to chronicity. Because of its high genetic variability, HCV has the capability to escape the immune response of the host. HCV is not directly cytopathic and liver lesions are mainly related to immune-mediated mechanisms, which are characterized by a predominant type 1 helper cell response. Co-factors influencing the outcome of the disease including age, gender and alcohol consumption are poorly understood and other factors such as immunologic and genetic factors may play an important role. Recent studies have shown that the combination therapy with alpha interferon and ribavirin induces a sustained virological response in about 40% of patients with chronic hepatitis C. The sustained response rates are mainly dependent on the viral genotype (roughly 60% in genotype non-1 and 30% in genotype 1). Reliable diagnostic tools are now available and useful for detecting HCV infection, to quantify viral load and to determine the viral type. The assessment of the viral quasispecies and the characterization of viral sequences might be clinically relevant but standardized and simple techniques are needed. The lack of animal models and of in vitro culture systems hampers the understanding of the pathogenesis of chronic hepatitis C and the development of new antivirals. New therapeutic schedules with higher and/or daily doses of alpha interferon do not seem to improve the efficacy greatly. The conjugation with polyethylene glycol (PEG) improved the pharmacodynamics and the efficacy of alpha interferon. Emerging new therapies include inhibitors of viral enzymes (protease, helicase and polymerase), cytokines (IL-12 and IL-10), antisense oligonucleotides and ribozymes. The first candidate compounds should be available in the next few years. The development of an effective vaccine remains the most difficult and pressing challenge. Because of the high protein variability of HCV, protective vaccines could be extremely difficult to produce and therapeutic vaccines seem more realistic. Considerable progress has been made in the field of HCV since its discovery 10 years ago but a major effort needs to be made in the next decade to control HCV-related liver disease.