Roles of iron and HFE mutations on severity and response to therapy during retreatment of advanced chronic hepatitis C

Association of genetic polymorphisms with interferon-induced haematologic adverse effects in chronic hepatitis C patients

Interferon (IFN)-based combination therapy with ribavirin has become the gold standard for the treatment of chronic hepatitis C virus infection. Haematologic toxicities, such as neutropenia, thrombocytopenia, and anaemia, however, frequently cause poor treatment tolerance, resulting in poor therapeutic efficacy. The aim of this study was to identify host genetic polymorphisms associated with the efficacy or haematologic toxicity of IFN-based combination therapy in chronic hepatitis C patients. We performed comprehensive single nucleotide polymorphism detection in all exonic regions of the 12 genes involved in the IFN signalling pathway in 32 healthy Japanese volunteers. Of 167 identified polymorphisms, 35 were genotyped and tested for an association with the efficacy or toxicity of IFN plus ribavirin therapy in 240 chronic hepatitis C patients. Multiple logistic regression analysis revealed that low viral load, viral genotypes 2 and 3, and a lower degree of liver fibrosis, but none of the genetic polymorphisms, were significantly associated with a sustained virologic response. In contrast to efficacy, multiple linear regression analyses demonstrated that two polymorphisms (IFNAR1 10848-A/G and STAT2 4757-G/T) were significantly associated with IFN-induced neutropenia (P = 0.013 and P = 0.011, respectively). Thrombocytopenia was associated with the IRF7 789-G/A (P = 0.031). In conclusion, genetic polymorphisms in IFN signalling pathway-related genes were associated with IFN-induced neutropenia and thrombocytopenia in chronic hepatitis C patients. In contrast to toxicity, the efficacy of IFN-based therapy was largely dependent on viral factors and degree of liver fibrosis.

Variants in interferon-alpha pathway genes and response to pegylated interferon-Alpha2a plus ribavirin for treatment of chronic hepatitis C virus infection in the hepatitis C antiviral long-term treatment against cirrhosis trial

Combination treatment with pegylated-interferon-alpha (PEG IFN-alpha) and ribavirin, the current recommended therapy for chronic hepatitis C virus (HCV) infection, results in a sustained virological response (SVR) in only about half of patients. Because genes involved in the interferon-alpha pathway may affect antiviral responses, we analyzed the relationship between variants in these genes and SVR among participants in the Hepatitis C Antiviral Long-Term treatment Against Cirrhosis (HALT-C) trial. Patients had advanced chronic hepatitis C that had previously failed to respond to interferon-based treatment. Participants were treated with peginterferon-alpha2a and ribavirin during the trial. Subjects with undetectable HCV RNA at week 72 were considered to have had an SVR. Subjects with detectable HCV RNA at week 20 were considered nonresponders. We used TaqMan assays to genotype 56 polymorphisms found in 13 genes in the interferon-alpha pathway. This analysis compares genotypes for participants with an SVR to nonresponders. The primary analysis was restricted to European American participants because a priori statistical power was low among the small number (n = 131) of African American patients. We used logistic regression to control the effect of other variables that are associated with treatment response. Among 581 European American patients, SVR was associated with IFNAR1 IVS1-22G (adjusted odds ratio, 0.57; P = 0.02); IFNAR2 Ex2-33C (adjusted odds ratio, 2.09; P = 0.02); JAK1 IVS22+112T (adjusted odds ratio, 1.66; P = 0.04); and ADAR Ex9+14A (adjusted odds ratio, 1.67; P = 0.03). For the TYK2-2256A promoter region variant, a borderline association was present among European American participants (OR, 1.51; P = 0.05) and a strong relationship among African American patients; all 10 with SVR who were genotyped for TYK2 -2256 carried the A variant compared with 68 of 120 (57%) nonresponders (P = 0.006).

CONCLUSION

Genetic polymorphisms in the interferon-alpha pathway may affect responses to antiviral therapy of chronic hepatitis C.

DNA polymorphisms and response to treatment in patients with chronic hepatitis C: results from the HALT-C trial

BACKGROUND/AIMS

Certain host genetic polymorphisms reportedly affect the likelihood of a sustained virological response (SVR) to interferon treatment in subjects infected with hepatitis C virus (HCV). As part of the HALT-C trial we evaluated genetic associations among patients infected with HCV genotype 1 who had failed previous interferon treatment.

METHODS

SVR was determined 24 weeks after completing treatment with pegylated interferon alfa-2a and ribavirin. Eight single nucleotide polymorphisms (SNPs) were selected on the basis of previously reported associations with treatment response. Genotypes were assessed by polymerase chain reaction-based assays. The percentage of patients who achieved SVR was determined for each genotype and for an IL10 promoter diplotype.

RESULTS

Among 637 non-Hispanic Caucasian patients there were no significant associations between genotype for any individual SNP (IL10-1082, IL10-592, TNF-308, TNF-238, TGFB1 codon 25, CCL2-2518, EPHX1 codon 113 and AGT-6) and SVR, but SVR was more common among the patients who were homozygous for the ACC IL10 promoter diplotype (adjusted odds ratio, 3.24; 95% confidence interval, 1.33-7.78; p=0.001).

CONCLUSIONS

Among non-Hispanic Caucasian patients treated with peginterferon and ribavirin after failing previous treatment with interferon, homozygosity for the ACC IL10 promoter diplotype was associated with SVR.

Treatment predictors of a sustained virologic response in hepatitis B and C

Treatment predictors are important tools for the management of therapy in patients with chronic hepatitis B and C virus (HBV, HCV) infection. In chronic hepatitis B, several pretreatment parameters have been identified for prediction of virologic response to interferon alfa-based antiviral therapies or treatment with polymerase inhibitors. In interferon alfa and pegylated interferon alfa-treated patients, low baseline HBV DNA concentrations, HBV genotype A (B), and high baseline ALT levels are significantly associated with treatment response. In patients treated with nucleos(t)ide analogues, low baseline HBV DNA but not viral genotype is positively associated with virologic response. During treatment the best predictor of response is HBV DNA kinetics. Early viral suppression is associated with favourable virologic response and reduced risk for subsequent resistance mutations. For the current standard treatment with pegylated interferon alfa and ribavirin in patients with chronic hepatitis C, infection with HCV genotypes 2 and 3, baseline viral load below 400,000-800,000 IU/ml, Asian and Caucasian ethnicity, younger age, low GGT levels, absence of advanced fibrosis/cirrhosis, and absence of steatosis in the liver have been identified as independent pretreatment predictors of a sustained virologic response. After initiation of treatment, initial viral decline with undetectable HCV-RNA at week 4 of therapy (RVR) is the best predictor of sustained virologic response independent of HCV genotype.

Co-factors in liver disease: the role of HFE-related hereditary hemochromatosis and iron

The severity of liver disease and its presentation is thought to be influenced by many host factors. Prominent among these factors is the level of iron in the body. The liver plays an important role in coordinating the regulation of iron homeostasis and is involved in regulating the level of iron absorption in the duodenum and iron recycling by the macrophages. Iron homeostasis is disturbed by several metabolic and genetic disorders, including various forms of hereditary hemochromatosis. This review will focus on liver disease and how it is affected by disordered iron homeostasis, as observed in hereditary hemochromatosis and due to HFE mutations. The types of liver disease covered herein are chronic hepatitis C virus (HCV) infection, alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD), end-stage liver disease, hepatocellular carcinoma (HCC) and porphyria cutanea tarda (PCT).

The effect of iron depletion on chronic hepatitis C virus infection

Increasing evidence exists that iron overload, a common finding in chronic hepatitis C virus (HCV) infection, plays an important role in the pathophysiology of this disease. The mechanisms by which iron excess induces liver damage along with the benefit of iron depletion via phlebotomy on biochemical and histological outcomes in patients with chronic HCV infection have been discussed in this review. Finally, we focus on the effect of iron reduction on the rate of response to interferon antiviral therapy.

Non-prescription supplement-induced hepatitis with hyperferritinemia and mutation (H63D) in the HFE gene

A 55-year-old Japanese woman was hospitalized because liver function tests showed an abnormality. Transaminases and biliary enzymes were markedly elevated with hyperferritinemia. Her imaging tests revealed no significant abnormality. She had been taking various non-prescription supplements for over approximately 6 months. After the supplements were discontinued her liver function gradually improved. This clinical course was suggestive of supplement-induced hepatitis. She had no history of taking supplements containing iron, so it was interesting that she had hyperferritinemia. We examined C282Y and H63D, which are important mutations in theiron-metabolizing gene, HFE. She was found to be heterozygous for the H63D mutation. The interaction between hyperferritinemia and supplements is unknown, but it can be speculated that some interaction between iron overload and supplements may have underlain the pathogenesis of her liver injury.

Phlebotomy improves therapeutic response to interferon in patients with chronic hepatitis C: a meta-analysis of six prospective randomized controlled trials

Prospective randomized controlled trials (RCTs) comparing phlebotomy and interferon (IFN) treatment to IFN alone in patients with chronic hepatitis C (CHC) have suggested a benefit for the phlebotomy group. However, statistical significance was achieved in only one of these trials. We performed a meta-analysis of RCTs comparing phlebotomy and IFN to IFN alone for the treatment of CHC. The MEDLINE database and Cochrane registry of controlled trials were searched using the key words "phlebotomy" and "treatment of hepatitis C." Reference lists of review articles discussing the interaction between iron and CHC, and prospective RCTs comparing phlebotomy plus IFN therapy to IFN alone were searched to identify additional RCTs that compared phlebotomy plus IFN to IFN alone. Peto odds ratios with their 95% confidence intervals and Forrest plots were generated for each variable to assess the relationships among the studies that had provided that information. Statistical analysis was performed using Comprehensive META-Analysis version 2.0. Six prospective RCTs were identified: all used sustained viral response (SVR) as an endpoint. The three largest RCTs excluded patients with cirrhosis. Two RCTs specifically included only patients with either high ferritin or high hepatic iron content. IFN treatment regimes varied. Length of treatment varied between 6 and 12 months. The phlebotomy plus IFN group and the IFN group did not differ with respect to the percentage of patients with cirrhosis or genotype 1. SVR was attained in 50/182 (27%) patients in the phlebotomy plus IFN group, compared to 22/185 (12%) patients in the IFN group. Peto odds ratio for SVR in phlebotomy plus IFN group was 2.7; 95% CI 1.6-4.5, P < 0.0001. All five RCTs published in manuscript form showed a trend towards a benefit from the phlebotomy plus IFN in attaining SVR, and the results of the meta-analysis were not dependent on any single RCT, since excluding any single RCT did not change the results. Phlebotomy improves the SVR in response to IFN treatment in patients with CHC. Confirmation of this will require RCT with detailed pre-treatment iron studies and appropriately powered to demonstrate a statistically significant benefit.

Iron chelation beyond transfusion iron overload

The effects of systemic iron overload in hereditary (e.g., classic HFE hemochromatosis) or acquired disorders (e.g., transfusion-dependent iron overload) are well known. Several other iron overload diseases, with an observed mild-to-moderate increase in iron in selected organs (e.g., the liver or the brain), or with "misdistribution" of iron within cells (e.g., reticuloendothelial cells) or subcellular organelles (e.g., mitochondria), have been recognized more recently. The deleterious impact of any excess iron may be high as active redox iron may directly contribute to cell damage or affect signaling pathways involved in cell necrosis-apoptosis or organ fibrosis and cancer. This article discusses the potential use of iron chelation therapy to treat iron overload from causes other than transfusion overload.

HFE gene in primary and secondary hepatic iron overload

Distinct from hereditary haemochromatosis, hepatic iron overload is a common finding in several chronic liver diseases. Many studies have investigated the prevalence, distribution and possible contributory role of excess hepatic iron in non-haemochromatotic chronic liver diseases. Indeed, some authors have proposed iron removal in liver diseases other than hereditary haemochromatosis. However, the pathogenesis of secondary iron overload remains unclear. The High Fe (HFE) gene has been implicated, but the reported data are controversial. In this article, we summarise current concepts regarding the cellular role of the HFE protein in iron homeostasis. We review the current status of the literature regarding the prevalence, hepatic distribution and possible therapeutic implications of iron overload in chronic hepatitis C, hepatitis B, alcoholic and non-alcoholic fatty liver diseases and porphyria cutanea tarda. We discuss the evidence regarding the role of HFE gene mutations in these liver diseases. Finally, we summarize the common and specific features of iron overload in liver diseases other than haemochromatosis.

Iron overload and cofactors with special reference to alcohol, hepatitis C virus infection and steatosis/insulin resistance

There are several cofactors which affect body iron metabolism and accelerate iron overload. Alcohol and hepatic viral infections are the most typical examples for clarifying the role of cofactors in iron overload. In these conditions, iron is deposited in hepatocytes and Kupffer cells and reactive oxygen species (ROS) produced through Fenton reaction have key role to facilitate cellular uptake of transferrin-bound iron. Furthermore, hepcidin, antimicrobial peptide produced mainly in the liver is also responsible for intestinal iron absorption and reticuloendothelial iron release. In patients with ceruloplasmin deficiency, anemia and secondary iron overload in liver and neurodegeneration are reported. Furthermore, there is accumulating evidence that fatty acid accumulation without alcohol and obesity itself modifies iron overload states. Ineffective erythropoiesis is also an important factor to accelerate iron overload, which is associated with diseases such as thalassemia and myelodysplastic syndrome. When this condition persists, the dietary iron absorption is increased due to the increment of bone marrow erythropoiesis and tissue iron overload will thereafter occurs. In porphyria cutanea tarda, iron is secondarily accumulated in the liver.

Serum measures of iron status and HFE gene mutations in patients with hepatitis B virus infection

AIM

We tested associations between HFE mutations and hepatitis B virus (HBV) infection. We also explored measures of total body iron status and their association with chronic HBV infection.

METHODS

Serum measures of iron status and HFE mutations (C282Y, H63D, and S65C) were assessed in 344 Iranian patients with chronic HBV infection (214 asymptomatic carriers, 130 patients with chronic progressive liver disease [CPLD]) and 302 controls.

RESULTS

Frequencies of HFE mutations did not differ between patients with chronic HBV infection and controls (C282Y: P=0.9, H63D: P= 0.8, S65C: P=0.9). By logistic regression, advanced hepatic fibrosis was associated with HFE H63D mutation (OR=13.1, P=0.006; 95% CI=2.0-84.1). Higher levels of serum ferritin and transferrin saturation were observed in patients with CPLD than in healthy controls (P=0.0001 and 0.01, respectively, adjusted for age and sex). None of the serum iron measures was related to liver fibrosis stage or necroinflammatory grade.

CONCLUSION

Serum iron measures are associated with chronic progressive hepatitis B. Carriage of HFE mutations is not associated with the presence of chronic HBV infection or values of serum iron measures in this population, although HFE H63D is associated with more advanced hepatic fibrosis.