Heterozygous beta-globin gene mutations as a risk factor for iron accumulation and liver fibrosis in chronic hepatitis C

Review article: iron disturbances in chronic liver diseases other than haemochromatosis - pathogenic, prognostic, and therapeutic implications

BACKGROUND

Disturbances in iron regulation have been described in diverse chronic liver diseases other than hereditary haemochromatosis, and iron toxicity may worsen liver injury and outcome.

AIMS

To describe manifestations and consequences of iron dysregulation in chronic liver diseases apart from hereditary haemochromatosis and to encourage investigations that clarify pathogenic mechanisms, define risk thresholds for iron toxicity, and direct management METHODS: English abstracts were identified in PubMed by multiple search terms. Full length articles were selected for review, and secondary and tertiary bibliographies were developed.

RESULTS

Hyperferritinemia is present in 4%-65% of patients with non-alcoholic fatty liver disease, autoimmune hepatitis, chronic viral hepatitis, or alcoholic liver disease, and hepatic iron content is increased in 11%-52%. Heterozygosity for the C282Y mutation is present in 17%-48%, but this has not uniformly distinguished patients with adverse outcomes. An inappropriately low serum hepcidin level has characterised most chronic liver diseases with the exception of non-alcoholic fatty liver disease, and the finding has been associated mainly with suppression of transcriptional activity of the hepcidin gene. Iron overload has been associated with oxidative stress, advanced fibrosis and decreased survival, and promising therapies beyond phlebotomy and oral iron chelation have included hepcidin agonists.

CONCLUSIONS

Iron dysregulation is common in chronic liver diseases other than hereditary haemochromatosis, and has been associated with liver toxicity and poor prognosis. Further evaluation of iron overload as a co-morbid factor should identify the key pathogenic disturbances, establish the risk threshold for iron toxicity, and promote molecular interventions.

Incidence of hepatocellular carcinoma reduced by phlebotomy treatment in patients with chronic hepatitis C

OBJECTIVE

To determine the impact of phlebotomy on the laboratory values and the incidence of hepatocellular carcinoma (HCC) in patients with hepatitis C.

METHODS

Study patients with chronic hepatitis C were treated with glycyrrhizin injection and oral ursodeoxycholic acid and either with (n=52) or without (n=50) phlebotomy during the period of 2005-2012. Six phlebotomized patients had previously received interferon therapy and were subsequently excluded from the data analysis. The serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin, alkaline phosphatase, gamma-glutamyl transpeptidase, lactate dehydrogenase, ferritin, iron and albumin, as well as the hemoglobin concentration, platelet count and prothrombin time, were determined. We compared the long-term outcomes based on the incidence of HCC and laboratory values, including the baseline serum ferritin levels, in patients treated with versus without phlebotomy.

RESULTS

In the phlebotomy group, the mean AST and ALT levels decreased significantly at each one-year interval over five years (p<0.01), whereas the platelet counts did not. The incidence of HCC in the phlebotomized patients was significantly lower than that observed in the patients treated without phlebotomy: 10.3% vs. 43.7%, respectively, during the 8-year observation period (p=0.04). The incidence of HCC was also lower in the phlebotomized patients with a normal baseline ferritin level: 0.0% vs. 36.0% in the matched subgroup treated without phlebotomy at year 8. Phlebotomy offered a risk ratio of 0.13, thus suggesting protection against the development of HCC.

CONCLUSION

The incidence of HCC can be reduced by phlebotomy treatment, which should be performed in patients with chronic hepatitis C not receiving or not responding to antiviral therapy.

Impact of the IL-18 gene polymorphism in response to antiviral therapy in chronic HCV genotype 4 patients

INTRODUCTION

Interleukin (IL)-18 is a well-known major proinflammatory cytokine with broad biological effects. The major immunomodulatory functions of IL-18 include enhancing T cell and natural killer cell cytotoxicity. Serum levels of this cytokine were shown to increase in chronic hepatitis C patients compared to non-infected healthy people. An association between IL-18 gene promoter polymorphisms and pegylated interferon (PEG-IFN) and ribavirin treatment outcomes has been reported for individuals with chronic hepatitis C virus genotype 1 (HCV-1). In this study, HCV genotype 4 (HCV-4) patients were assessed for IL-18 gene polymorphisms and treatment outcomes or severity of liver disease because data concerning the impact of IL-18 gene polymorphisms on patients with HCV-4 infections are limited.

METHODS

This study included 123 chronic HCV-4 Egyptian patients and 123 apparently healthy volunteer blood donors who served as a control group. HCV genotyping was performed using the line probe assay. IL-18 genotyping was performed using the TaqMan Real-Time PCR method in all 246 patient and control samples.

RESULTS

In our study, all patients had HCV-4. IL-18 gene single nucleotide polymorphism (SNP) (-607C/A) genotype distributions and allele frequencies did not differ between HCV patients and normal healthy subjects or between patient groups when compared according to the therapeutic response. Moreover, the presence of an IL-18 SNP was not associated with histological disease severity. We conclude that the presence of the IL-18 SNP rs1946518 does not affect the outcome of chronic HCV-4 treatment in Egyptian patients.

CONCLUSIONS

The IL-18 SNP rs1946518 does not affect response to treatment in chronic HCV-4 patients.

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.

A case-control histological study on the effects of phlebotomy in patients with chronic hepatitis C

OBJECTIVE

The aim of this study was to assess the actual effectiveness of long-term phlebotomy by comparing histological improvement (HI) in 69 Caucasian HCV-RNA-positive CHC patients undergoing phlebotomy or receiving an interferon-based therapy without virological response [nonresponders to interferon therapy(IBT-NR)].

METHODS

HI was defined by at least one point reduction of the staging score or, in the case of unchanged stage, by at least two points reduction of the grading score (Knodel's Activity Index) and was retrospectively evaluated by comparing two consecutive (56 ± 28 months apart) liver biopsies from 30 phlebotomized and 39 IBT-NR patients.

RESULTS

HI was observed in 15 of 30 (50%) patients treated with phlebotomy and in six of 39 (15%) IBT-NR subjects (P=0.002). Furthermore, AST, ALT, and GGT serum levels were significantly reduced only in phlebotomized patients (P ≤ 0.003) at the time of the second biopsy. Univariate and multivariate analysis showed that histological grading score before therapy (P=0.001) and phlebotomy (P=0.002) were independently predictors of HI.

CONCLUSION

HI induced by long-term phlebotomy effectively exceeds that spontaneously occurring in patients IBT-NR confirming the efficacy of iron depletion in attenuating CHC progression when other therapies have failed.

Beyond hereditary hemochromatosis: new insights into the relationship between iron overload and chronic liver diseases

Following the model of hereditary hemochromatosis, the possible role of iron overload as a cofactor for disease progression in acquired liver diseases has been investigated with controversial results. In recent years, progress has been made in understanding the regulation of iron metabolism, thereby allowing the evaluation of the mechanisms linking liver diseases to excessive iron accumulation. Indeed, deregulation of the transcription of hepcidin, emerging as the master regulator of systemic iron metabolism, has been implicated in the pathogenesis of hepatic iron overload in chronic liver diseases. Whatever the cause, hepatocellular iron deposition promotes liver fibrogenesis, while an emerging possible aggravating factor is represented by the strong link between iron stores and insulin resistance, a recently recognized risk factor for the progression of liver diseases. Overall, these pathogenic mechanisms, together with the known proliferative and mutagenic effect of excess iron, converge in determining an increased susceptibility to hepatocellular carcinoma. Finally, an association between serum ferritin levels and mortality in patients with end-stage liver disease has recently been reported. Prospective, randomized studies are required to evaluate whether iron depletion may reduce fibrosis progression, hepatocellular carcinoma development, and eventually mortality in patients with chronic liver diseases.

Beta-globin mutations are associated with parenchymal siderosis and fibrosis in patients with non-alcoholic fatty liver disease

BACKGROUND & AIMS

Parenchymal liver siderosis is associated with increased fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). The aim of this study was to assess whether a panel of genetic variants previously reported to influence iron metabolism, including the C282Y/H63D HFE, the PiZ/PiS alpha1-antitrypsin, the IVS1-24 ferroportin polymorphisms, and the beta-thalassemia trait, may be able to predict the presence of parenchymal siderosis and of progressive fibrosis in NAFLD.

METHODS

We considered 274 Italian patients with biopsy-proven NAFLD. Genetic polymorphisms were searched for by sequence allele specific-polymerase chain reaction and restriction analysis, whereas beta-trait was determined according to blood count and HbA(2) determination.

RESULTS

Parenchymal iron deposition was predominantly observed in 32 (11.7%) patients. Heterozygosity for the C282Y (OR 1.87, 95% CI 1.04-3.25), homozygosity for the H63D HFE (OR 2.31, 95% CI 1.04-4) mutations, and the beta-thalassemia trait (OR 2.57 95% CI 1.49-4.47) were all predominantly associated with parenchymal siderosis, independently of age, sex, body mass index, alcohol intake, ferritin, and transferrin saturation. Sixty-three percent of patients with hepatocellular siderosis were positive for at least one of the aforementioned genetic variants. The beta-thalassemia trait had the highest positive and the lowest negative likelihood ratios for predominantly parenchymal iron accumulation (5.05 and 0.74, respectively), and was independently associated with moderate/severe fibrosis (OR 2.50, 95% CI 1.26-5.19).

CONCLUSIONS

In patients with NAFLD, predominant hepatocellular iron deposition is often related to genetic factors, among which beta-globin mutations play a major role, predisposing to parenchymal iron accumulation and to progressive liver fibrosis.

HFE genotype, parenchymal iron accumulation, and liver fibrosis in patients with nonalcoholic fatty liver disease

BACKGROUND & AIMS

Mutations in the hemochromatosis gene (HFE) (C282Y and H63D) lead to parenchymal iron accumulation, hemochromatosis, and liver damage. We investigated whether these factors also contribute to the progression of fibrosis in patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

We studied clinical, histologic (liver biopsy samples for hepatocellular iron accumulation), serologic (iron and enzyme levels), and genetic (HFE genotype) data from 587 patients from Italy with NAFLD and 184 control subjects.

RESULTS

Iron accumulation predominantly in hepatocyes was associated with a 1.7-fold higher risk of a fibrosis stage greater than 1 (95% confidence interval [CI]: 1.2-2.3), compared with the absence of siderosis (after adjustment for age, body mass index, glucose tolerance status, and alanine aminotransferase level). Nonparenchymal/mixed siderosis was not associated with moderate/severe fibrosis (odds ratio, 0.72; 95% CI: 0.50-1.01). Hepatocellular siderosis was more prevalent in patients with HFE mutations than in those without; approximately one third of patients with HFE mutations had parenchymal iron accumulation (range, 29.8%-35.7%, depending on HFE genotype). Predominantly hepatocellular iron accumulation occurred in 52.7% of cases of patients with HFE mutations. There was no significant association between either the presence of HFE mutations or specific HFE genotypes and the severity of liver fibrosis.

CONCLUSIONS

Iron deposition predominantly in hepatocyes is associated with more severe liver damage in patients with NAFLD. However, HFE mutations cannot be used to identify patients with hepatocellular iron accumulation.

Phlebotomy improves histology in chronic hepatitis C males with mild iron overload

AIM: To investigate the usefulness of mild iron depletion and the factors predictive for histological improvement following phlebotomy in Caucasians with chronic hepatitis C (CHC).

METHODS: We investigated 28 CHC Caucasians with persistently elevated serum aminotransferase levels and non responders to, or unsuitable for, antiviral therapy who underwent mild iron depletion (ferritin ≤ 70 ng/mL) by long-term phlebotomy. Histological improvement, as defined by at least one point reduction in the staging score or, in case of unchanged stage, as at least two points reduction in the grading score (Knodell), was evaluated in two subsequent liver biopsies (before and at the end of phlebotomy, 48 ± 16 mo apart).

RESULTS: Phlebotomy showed an excellent safety profile. Histological improvement occurred in 12/28 phlebotomized patients. Only males responded to phlebotomy. At univariate logistic analysis alcohol intake (P = 0.034), high histological grading (P = 0.01) and high hepatic iron concentration (HIC) (P = 0.04) before treatment were associated with histological improvement. Multivariate logistic analysis showed that in males high HIC was the only predictor of histological improvement following phlebotomy (OR = 1.41, 95% CI: 1.03-1.94, P = 0.031). Accordingly, 12 out of 17 (70%) patients with HIC ≥ 20 μmol/g showed histological improvements at the second biopsy.

CONCLUSION: Male CHC Caucasian non-responders to antiviral therapy with low-grade iron overload can benefit from mild iron depletion by long-term phlebotomy.

Interaction of Hb South Florida (codon 1; GTG-->ATG) and HbE, with beta-thalassemia (IVS1-1; G-->A): expression of different clinical phenotypes

INTRODUCTION

Interactions of different hemoglobin variants with thalassemia alleles can result in various clinical phenotypes. HbE-beta-thalassemia generally manifests with severe anemia where individuals exhibit beta-thalassemia major with regular blood transfusions or beta-thalassemia intermedia with periodic blood transfusions. This study presents a unique Malay family with three beta-globin gene defects-HbE, Hb South Florida, and IVS1-1 (G-->A).

MATERIALS AND METHODS

HbE activates a cryptic splice site that produces non-functional mRNAs. Hb South Florida is a rare beta-hemoglobin variant, and its interactions with other beta-thalassemia alleles have not been reported. IVS1-1 is a Mediterranean mutation that affects mRNA processing giving rise to beta(o)-thalassemia.

RESULTS AND DISCUSSION

Fifteen mutations along the beta-globin gene complex were analyzed using the amplification refractory mutation system. Hb South Florida was identified by direct sequencing using genomic DNA.

CONCLUSION

The affected child with HbE/IVS1-1 produced a beta-thalassemia major phenotype. Compound heterozygosity for Hb South Florida/IVS1-1 produced a beta-thalassemia carrier phenotype in the mother.

Interleukin 18 promoter variants (-137G>C and -607C>A) in patients with chronic hepatitis C: association with treatment response

BACKGROUND

Recently, two functional IL18 promoter variants, -607C>A (rs1946518) and -137G>C (rs187238), were associated with viral clearance in patients with hepatitis C. The present study focused on their relevance for treatment response.

METHODS

Seven hundred fifty-seven chronically infected European patients and 791 controls were enrolled in the study. IL18 genotyping was performed by allele-specific PCR. Liver histology was available in 67.9%.

RESULTS

Genotype and allele frequencies were equally distributed in patients and controls. No significant association with various disease characteristics was observed. However, when comparing patients with sustained virological response (SR) and non-SR, statistically significant associations were found for both variants (p = 0.0416 and p = 0.0274, respectively). In viral genotype 1, the -607A allele was positively associated with treatment response (p = 0.0190; OR 1.537; 95% CI, 1.072-2.205) and the -137G allele with a higher rate of nonresponse (p = 0.0302; OR 1.524; 95% CI, 1.040-2.233).

CONCLUSIONS

The association of IL18 variants with treatment response in genotype 1 hepatitis C patients implies a predictive and modifying role of these genetic variants.

Viral infection and iron metabolism

Fundamental cellular operations, including DNA synthesis and the generation of ATP, require iron. Viruses hijack cells in order to replicate, and efficient replication needs an iron-replete host. Some viruses selectively infect iron-acquiring cells by binding to transferrin receptor 1 during cell entry. Other viruses alter the expression of proteins involved in iron homeostasis, such as HFE and hepcidin. In HIV-1 and hepatitis C virus infections, iron overload is associated with poor prognosis and could be partly caused by the viruses themselves. Understanding how iron metabolism and viral infection interact might suggest new methods to control disease.

Disease progression in chronic hepatitis C: modifiable and nonmodifiable factors

The hepatic complications of chronic hepatitis C (CHC) usually occur only after progression to cirrhosis has taken place. Progression to cirrhosis, however, is extremely variable and depends on a broad set of host and viral factors that modify the rate at which fibrosis develops in a given individual. Despite their inherent limitations, studies of the natural history of CHC have identified several nonmodifiable factors associated with disease progression. These include age at acquisition of infection, sex, and race. More recent reports suggest important roles for host genetic polymorphisms and viral factors. Of greater immediate relevance to patients and their clinicians are the potentially modifiable factors, which include excessive alcohol consumption; smoking (tobacco and marijuana); insulin resistance; and coinfection with hepatitis B virus, human immunodeficiency virus type 1, or schistosomiasis. Unfortunately, to date, there are no reliable predictive models that can accurately estimate the risk of CHC disease progression.

Iron, haemochromatosis and thalassaemia as risk factors for fibrosis in hepatitis C virus infection

Iron depletion is required in patients with HCV and iron overload to retard liver fibrosis