A pilot study of iron depletion as adjuvant therapy in chronic hepatitis C patients not responding to interferon

HCV and oxidative stress in the liver

Hepatitis C virus (HCV) is the etiological agent accounting for chronic liver disease in approximately 2-3% of the population worldwide. HCV infection often leads to liver fibrosis and cirrhosis, various metabolic alterations including steatosis, insulin and interferon resistance or iron overload, and development of hepatocellular carcinoma or non-Hodgkin lymphoma. Multiple molecular mechanisms that trigger the emergence and development of each of these pathogenic processes have been identified so far. One of these involves marked induction of a reactive oxygen species (ROS) in infected cells leading to oxidative stress. To date, markers of oxidative stress were observed both in chronic hepatitis C patients and in various in vitro systems, including replicons or stable cell lines expressing viral proteins. The search for ROS sources in HCV-infected cells revealed several mechanisms of ROS production and thus a number of cellular proteins have become targets for future studies. Furthermore, during last several years it has been shown that HCV modifies antioxidant defense mechanisms. The aim of this review is to summarize the present state of art in the field and to try to predict directions for future studies.

Identification of treatment efficacy-related host factors in chronic hepatitis C by ProteinChip serum analysis

Recent development of proteomic array technology, including protein profiling coupling ProteinChip array with surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF/MS), provides a potentially powerful tool for discovery of new biomarkers by comparison of its profiles according to patient phenotypes. We used this approach to identify the host factors associated with treatment response in patients with chronic hepatitis C (CHC) receiving a 48-wk course of pegylated interferon (PEG-IFN) alpha 2b plus ribavirin (RBV). Protein profiles of pretreatment serum samples from 32 patients with genotype 1b and high viral load were conducted by SELDI-TOF/MS by using the three different ProteinChip arrays (CM10, Q10, IMAC30). Proteins showed significantly different peak intensities between sustained virological responders (SVRs), and non-SVRs were identified by chromatography, SDS-PAGE, TOF/MS and tandem mass spectrometry (MS/MS) assay. Eleven peak intensities were significantly different between SVRs and non-SVRs. The three SVR-increased peaks could be identified as two apolipoprotein (Apo) fragments and albumin and, among the eight non-SVR-increased proteins, four peaks identified as two iron-related and two fibrogenesis-related protein fragments, respectively. Multivariate analysis showed that the serum ferritin and three peak intensity values (Apo A1, hemopexin and transferrin) were independent variables associated with SVRs, and the area under the receiver operating characteristic (ROC) curves for SVR prediction by using the Apo A1/hemopexin and hemopexin/transferrin were 0.964 and 0.936. In conclusion, pretreatment serum protein profiling by SELDI-TOF/MS is variable for identification of response-related host factors, which are useful for treatment efficacy prediction in CHC receiving PEG-IFN plus RBV. Our data also may help us understand the mechanism for treatment resistance and development of more effective antiviral therapy targeted toward the modulation of lipogenesis or iron homeostasis in CHC patients.

The role of iron in the pathophysiology and treatment of chronic hepatitis C

Increased hepatic iron content may be observed in patients with chronic hepatitis C infection, and may contribute to disease severity. The presence of hemochromatosis gene mutations is associated with increased hepatic iron accumulation and may lead to accelerated disease progression. Hepatic iron depletion has been postulated to decrease the risk of hepatocellular carcinoma in patients with cirrhosis due to chronic hepatitis C. It is possible that iron depletion stabilizes or improves liver histology and slows disease progression in these individuals. The present article reviews the prevalence and risk factors for hepatic iron overload in chronic hepatitis C, with emphasis on the available data regarding the efficacy of iron depletion in the treatment of this common liver disease.

The role of iron in the pathophysiology and treatment of chronic hepatitis C

Increased hepatic iron content may be observed in patients with chronic hepatitis C infection, and may contribute to disease severity. The presence of hemochromatosis gene mutations is associated with increased hepatic iron accumulation and may lead to accelerated disease progression. Hepatic iron depletion has been postulated to decrease the risk of hepatocellular carcinoma in patients with cirrhosis due to chronic hepatitis C. It is possible that iron depletion stabilizes or improves liver histology and slows disease progression in these individuals. The present article reviews the prevalence and risk factors for hepatic iron overload in chronic hepatitis C, with emphasis on the available data regarding the efficacy of iron depletion in the treatment of this common liver disease.

Iron increases translation initiation directed by internal ribosome entry site of hepatitis C virus

Although increased liver iron in individuals with chronic hepatitis C virus (HCV) is associated with a poor response to interferon therapy, the underlying molecular mechanisms are poorly understood. In this study, we show that iron enhances the translation initiation mediated by the internal ribosome entry site (IRES) of HCV. We also demonstrate by UV cross-linking analysis that specific cellular proteins bind to HCV 5' untranslated region (5' UTR) in an iron-dependent manner. Notably, p85 and p110 are competed out for their binding to HCV 5' UTR when excess amounts of iron-responsive element (IRE) competitor RNAs are treated. This indicates that at least these two factors are common proteins for binding to HCV 5' UTR and IRE. Our results, taken together, suggest that intracellular iron modulates the iron sensing pathway and HCV IRES-dependent translation by changing the binding affinities of the common cellular factors to IRE and HCV IRES, respectively. As a consequence, the coordinated regulation of gene expression by intracellular iron could provide favorable conditions for HCV proliferation.

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.

Hepatic iron accumulation is associated with disease progression and resistance to interferon/ribavirin combination therapy in chronic hepatitis C

BACKGROUND AND AIMS

Liver iron accumulation in patients with chronic hepatitis C (CHC) has received increasing attention in recent years. The aim of this study was to determine the prevalence and severity of liver iron deposition in CHC, to assess its relationship with clinical, biochemical and histological characteristics, and to study its influence on the response to interferon (IFN) plus ribavirin combination therapy.

METHODS

We studied liver biopsy specimens from 103 hepatitis C virus (HCV) and 34 hepatitis B virus (HBV) infected patients and total iron score (TIS) was measured. Seventy patients infected with HCV genotype 1b were treated with IFN/ribavirin for 24 weeks.

RESULTS

CHC patients had a significantly higher TIS than chronic hepatitis B (CHB) patients (7.03 +/- 5.34 vs 4.41 +/- 4.49, P = 0.0056). TIS was significantly correlated with alcohol intake (P = 0.0213, r = 0.290), transaminase level (P = 0.0126, r = 0.247), platelet count (P = 0.0002, r = -0.369), histological grading (P = 0.0121, r = 0.248) and staging (P = 0.0003, r = 0.356) in CHC patients. Pretreatment TIS was significantly higher in non-sustained virological responders (SVR) than in SVR to IFN/ribavirin treatment (TIS = 7.69 +/- 5.76 vs 4.39 +/- 3.27, P = 0.0310). Multiple regression analysis showed that TIS was the only independent variable associated with resistance to IFN/ribavirin (P = 0.0277).

CONCLUSIONS

Liver iron deposition was common in CHC compared to CHB and was associated with liver disease progression. Increased hepatic iron stores in CHC were related to resistance to IFN/ribavirin treatment.

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.

Effect of iron depletion on serum markers of fibrogenesis, oxidative stress and serum liver enzymes in chronic hepatitis C: results of a pilot study

BACKGROUND

Hepatic iron deposition has been associated with decreased response to interferon-alpha monotherapy, and has been speculated to contribute to disease progression in chronic hepatitis C (CHC). We performed this study to evaluate the effect of iron depletion on biochemical and virologic markers, and markers of lipid peroxidation and fibrogenesis.

MATERIALS AND METHODS

Eighteen patients with CHC who did not have a virologic response to interferon monotherapy underwent weekly phlebotomies until iron depletion (serum ferritin <50 ng/ml). Serum levels of alanine transaminase (ALT), hepatitis C virus-RNA, transferrin saturation, ferritin, 8-isoprostane, hyaluronic acid, amino-terminal procollagen III peptide and YKL-40 were measured before and after iron depletion.

RESULTS

There was a statistically significant reduction of serum ALT, transferrin saturation and serum ferritin after iron depletion (range 4-11 phlebotomies). Serum ALT returned to normal after iron depletion in four (22%) patients. There was a significant reduction in serum procollagen III peptide level among patients who achieved biochemical response. No significant reduction was noted in serum levels of other markers.

CONCLUSIONS

Iron depletion was associated with a biochemical response in 22% of patients who did not respond to interferon monotherapy. There was a significant reduction in a key marker of fibrogenesis among patients with biochemical response. These data support longer-term studies of iron depletion in CHC.

Iron, the HFE gene, and hepatitis C

Intrahepatic iron overload is commonly seen in chronic hepatitis C infection. High levels of intrahepatic iron may lead to accelerated liver injury and development of fibrosis and cirrhosis. This is frequently seen in hereditary hemochromatosis, which in most of the cases is caused by homozygous mutations in the HFE gene. In patients suffering from chronic hepatitis C, the presence of heterozygous HFE mutations associates with higher hepatic iron scores and advanced stages of fibrosis. HFE mutations must therefore be considered as important comorbidity factors in chronic hepatitis C infection.

Racial differences in the relationship between hepatitis C infection and iron stores

Black race and increased hepatic iron stores predict poor response to interferon treatment for chronic hepatitis C virus (HCV) infection. We tested the hypothesis that these 2 observations are linked by investigating whether HCV-infected African-Americans have increased iron stores relative to uninfected persons. Using data from the third National Health and Nutrition Examination Survey (NHANES III), we determined the risk of having increased iron stores, defined as elevation of both serum ferritin and transferrin-iron saturation (TS), in HCV-RNA-positive blacks (n = 100) and nonblacks (n = 126) relative to HCV-RNA-negative blacks (n = 4,002) and nonblacks (n = 10,943). HCV-positive blacks were 5.4 times (95% CI, 1.2 to 24) more likely to have increased iron stores than HCV-positive nonblacks. The proportion of HCV-positive blacks who had increased iron stores was 16.4% among those with abnormal liver enzymes and 2.8% among those with normal liver enzymes, compared with only 0.6% among HCV-negative blacks. After adjustment for age, alcohol intake, gender, menopausal status, education, body mass index, and poverty index, HCV-positive blacks with abnormal liver enzymes had an elevated risk of having increased iron stores (odds ratio, 17.8; 95% CI, 5.1 to 63). In contrast, among persons of other races, there was a much smaller difference in the proportion of persons with increased iron stores between HCV-positive persons with (3.4%) or without (1.4%) abnormal liver enzymes and HCV-negative persons (0.9%). In conclusion, a greater proportion of blacks than persons of other races respond to HCV infection with an increase in iron stores. This finding may partly explain the reduced response of HCV-positive African-Americans to antiviral treatment.

Iron overload disorders

Because hepatic siderosis is a frequent finding, there is a risk of making it trite when elaborating the pathology report. Iron is increasingly considered an important cofactor of morbidity. Its finding in hepatic cells must be recognized, indicated, qualified, quantified, and interpreted. A systematic reasoning based on a strict semiological approach allows for guiding the clinician. Iron overload syndromes do not amount to genetic hemochromatosis only.

The chimpanzee model of hepatitis C virus infections

The chimpanzee (Pan troglodytes) is the only experimental animal susceptible to infection with hepatitis C virus (HCV). The chimpanzee model of HCV infection was instrumental in the initial studies on non-A, non-B hepatitis, including observations on the clinical course of infection, determination of the physical properties of the virus, and eventual cloning of the HCV nucleic acid. This review focuses on more recent aspects of the use of the chimpanzee in HCV research. The chimpanzee model has been critical for the analysis of early events in HCV infection because it represents a population for which samples are available from the time of exposure and all exposed animals are examined. For this reason, the chimpanzee represents a truly nonselected population. In contrast, human cohorts are often selected for disease status or antibody reactivity and typically include individuals that have been infected for decades. The chimpanzee model is essential to an improved understanding of the factors involved in viral clearance, analysis of the immune response to infection, and the development of vaccines. The development of infectious cDNA clones of HCV was dependent on the use of chimpanzees, and they will continue to be needed in the use of reverse genetics to evaluate critical sequences for viral replication. In addition, chimpanzees have been used in conjunction with DNA microarray technology to probe the entire spectrum of changes in liver gene expression during the course of HCV infection. The chimpanzee will continue to provide a critical aspect to the understanding of HCV disease and the development of therapeutic modalities.

Hepatitis C

In the latter half of the 20th century, HCV emerged as the most common cause of chronic liver disease, and will likely remain so. Since its initial discovery in 1989, rapid progress has been made in our understanding of the virology, epidemiology, natural history, diagnosis, and treatment of HCV. Over the next few decades, as further advancements are made, superior treatment options will become available.

Treatment of chronic hepatitis C in nonresponders to interferon monotherapy

Sixty percent of patients fail to respond to interferon monotherapy. African-Americans with hepatitis C appear to respond less well to interferon monotherapy. Retreatment with a higher dose of consensus interferon for 48 weeks has led to a sustained virologic response rate of 13%. As a group, interferon nonresponders who breakthrough while on interferon monotherapy seem to have a more favorable response rate to a repeat course of treatment. Retreatment with interferon and ribavirin for 6 months in nonresponders led to a sustained virologic response rate of 21%. Preliminary results from two trials in the United States demonstrate similar treatment efficacy. There is now evidence that maintenance interferon therapy may also be beneficial in interferon monotherapy nonresponders.

Benefits and dangers of iron during infection

Iron is essential for both human and microbial metabolism, and it is therefore important that iron status is maintained at a level that permits optimal immune responses by the host but does not facilitate availability of iron to microorganisms. This paper reviews the role of iron in resistance to infection, with particular reference to malaria and hepatitis C, and discusses the desirability of iron supplementation of populations at risk of infection.