HLA class I allelic diversity and progression of fibrosis in patients with chronic hepatitis C

Treatment of Liver Fibrosis: A 20-Year Bibliometric and Knowledge-Map Analysis

Objectives: To analyze the research hotspots, evolution, and trends of the treatment of liver fibrosis in the recent 20 years, bibliometric and knowledge-map analysis were used.

Methods: Publications associated with the treatment of liver fibrosis were retrieved from the Web of Science Core Collection on 16 April 2022. CiteSpace 5.8.R3 and VOSviewer 1.6.18 were calculated to perform bibliometric and knowledge-map analysis.

Results: A total of 72,686 authors from 200 institutions in 134 countries/regions published 15,237 studies in different academic journals. United States was the most productive country, and Shanghai Jiao Tong University was the most published institution. Trauner Michael had the most published articles, whereas Scott L. Friedman was the most frequently co-cited author. Moreover, there was frequent inter-institution cooperation between countries in the years 2015 and after, but the before years showed rare inter-institution cooperation. The journal HEPATOLOGY was both the most published publication and the most frequently co-cited one in this field. Screened keywords, such as virus infection, inflammation, oxidative stress, activation of hepatic stellate cell (HSC), and hepatocellular apoptosis, could be both therapeutic targets and pathological mechanisms in terms of liver fibrosis. Furthermore, long-term suppression of hepatitis B virus replication and the activation of HSC were the latest hotspots and topics related to the treatment of liver fibrosis. Besides, the treatments of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis were also involved in the treatment of liver fibrosis, which were both emerging topics and rapidly developing hot fields.

Conclusion: This bibliometric analysis conducted a full overview of the treatment of liver fibrosis, which provided important clues and ideas for scholars focusing on this field. Not only that, the field is still in a stage of rapid development and will continue to be a research hotspot in the future.

Single MHC-I Expression Promotes Virus-Induced Liver Immunopathology

Major histocompatibility complex I (MHC-I) molecules present epitopes on the cellular surface of antigen-presenting cells to prime cytotoxic clusters of differentiation 8 (CD8)⁺ T cells (CTLs), which then identify and eliminate other cells such as virus-infected cells bearing the antigen. Human hepatitis virus cohort studies have previously identified MHC-I molecules as promising predictors of viral clearance. However, the underlying functional significance of these predictions is not fully understood. Here, we show that expression of single MHC-I isomers promotes virus-induced liver immunopathology. Specifically, using the lymphocytic choriomeningitis virus (LCMV) model system, we found MHC-I proteins to be highly up-regulated during infection. Deletion of one of the two MHC-I isomers histocompatibility antigen 2 (H2)-Db or H2-Kb in C57Bl/6 mice resulted in CTL activation recognizing the remaining MHC-I with LCMV epitopes in increased paucity. This increased CTL response resulted in hepatocyte death, increased caspase activation, and severe metabolic changes in liver tissue following infection with LCMV. Moreover, depletion of CTLs abolished LCMV-induced pathology in these mice with resulting viral persistence. In turn, natural killer (NK) cell depletion further increased antiviral CTL immunity and clearance of LCMV even in the presence of a single MHC-I isomer. Conclusion: Our results suggest that uniform MHC-I molecule expression promotes enhanced CTL immunity during viral infection and contributes to increased CTL-mediated liver cell damage that was alleviated by CD8 or NK cell depletion.

HLA-E gene polymorphisms in chronic hepatitis C: Impact on HLA-E liver expression and disease severity

Hepatitis C virus usually produces chronic infection and liver damage. Considering that: i) the human leukocyte antigen-E (HLA-E) molecule may modulate the immune response, and ii) little is known about the role of HLA-E gene variability on chronic hepatitis C, we studied the impact of HLA-E polymorphisms on the magnitude of HLA-E liver expression and severity of hepatitis C. HLA-E variability was evaluated in terms of: i) single nucleotide polymorphism (SNP) alleles and genotypes along the gene (beginning of the promoter region, coding region and 3'UTR), and ii) ensemble of SNPs that defines the coding region alleles, considered individually or as genotypes. The comparisons of the HLA-E variation sites between patients and controls revealed no significant results. The HLA-E + 424 T > C (rs1059510), +756 G > A (rs1264457) and + 3777 G > A (rs1059655) variation sites and the HLA-E*01:01:01:01 and HLA-E*01:03:02:01 alleles, considered at single or double doses, were associated with the magnitude of HLA-E liver expression in Kupfer cell, steatosis, inflammatory activity and liver fibrosis. Although these associations were lost after corrections for multiple comparisons, these variable sites may propitiate biological clues for the understanding of the mechanisms associated with hepatitis C severity.

Influence of HLA-B18 on liver fibrosis progression in a cohort of HIV/HCV coinfected individuals

Liver fibrosis is accelerated in human immunodeficiency virus/hepatitis C virus (HIV/HCV) coinfected compared with HCV monoinfected patients, due to multiple cofactors. Recently, HLA-B18 haplotype has been associated with short-term liver disease progression in this population. Our aim was to assess the influence of HLA-B18 on the fibrosis process in HIV/HCV coinfected individuals, untreated for HCV, during a long-term follow-up. All consecutive HIV/HCV co-infectedcoinfected patients followed in our center, with positive HCV-RNA and available human leukocyte antigen (HLA) haplotypes (determined by sequence-specific oligonucleotide primed polymerase chain reaction and simple sequence repeats polymerase chain reaction using Luminex Technology) were included. Liver fibrosis progression was assessed by means of fibrosis-4 index for liver fibrosis (FIB-4) and AST to platelet ratio index. The association between FIB-4 score over time and laboratory and clinical parameters, including HLA, was evaluated by univariate and multivariate multilevel generalized linear models. A total of 29 out of 148 screened patients were excluded because of spontaneous HCV clearance (27% were HLA-B18+). Among the remaining 119 individuals (82% males; median age at first visit = 30 years [interquartile range, IQR, 26-35]; median follow-up = 21.5 years [IQR, 15-25]), 26% were HLA-B18+. No baseline differences were evidenced between HLA-B18+ and B18- patients. Fibrosis progression was significantly faster in HLA-B18+ than in HLA-B18- patients ( P < 0.001) (Figure 1). At univariate analysis, age ( P < 0.001), HLA-B18 haplotype ( P = 0.02) and HIV-RNA viral load overtime ( P < 0.001) were associated with liver disease progression. At multivariate analysis, only age ( P < 0.001) remained independently associated with liver fibrosis progression. Our data suggest a possible association between HLA-B18 and an accelerated liver fibrosis in HIV/HCV coinfected with a long-term follow-up.

Pharmacogenetics and the treatment of HIV-/HCV-coinfected patients

This review will summarize the role of pharmacogenetics in the natural history of hepatitis C, particularly in patients with HIV/HCV and will take the perspective of pharmacogenetics and its influence on the response to antiviral therapy and the susceptibility to develop adverse effects. This review will also devote a section to host genetics in other clinical situations, such as disease progression and acute HCV infection, which may determine whether treatment of HIV-/HCV-coinfected patients is implemented or deferred.

Role of Some Predominant Host Immunomodulators' Single Nucleotide Polymorphisms in Severity of Hepatitis B Virus and Hepatitis C Virus Infection

Hepatitis B and C infections can be either acute or chronic. The chronic infection can culminate in liver cirrhosis and hepatocellular carcinoma. Influence of the host genetic makeup on conversion of acute to chronic infection, development of cirrhosis, and hepatocellular carcinoma is an interesting area of research. Variability in different immune system genes may account for such differences in the outcome of infection. This article discusses single nucleotide polymorphisms in different host immunomodulator genes that have been frequently reported to influence the outcome of infection and severity of disease. The genetic variability could be utilized for the prediction of disease outcome and treatment responses.

Tackling the burden of the hepatitis C virus in the UK: characterizing and assessing the clinical and economic consequences

OBJECTIVES

The hepatitis C virus (HCV) remains a significant public health issue. This study aimed to quantify the clinical and economic burden of chronic hepatitis C in the UK, stratified by disease severity, age and awareness of infection, with concurrent assessment of the impact of implementing a treatment prioritization approach.

STUDY DESIGN AND METHODS

A previously published back projection, natural history and cost-effectiveness HCV model was adapted to a UK setting to estimate the disease burden of chronic hepatitis C and end-stage liver disease (ESLD) between 1980 and 2035. A published meta-regression analysis informed disease progression, and UK-specific data informed other model inputs.

RESULTS

At 2015, prevalence of chronic hepatitis C is estimated to be 241,487 with 22.20%, 33.72%, 17.22%, 16.67% and 10.19% of patients in METAVIR stages F0, F1, F2, F3 and F4, respectively, but is estimated to fall to 193,999 by 2035. ESLD incidence is predicted to peak in 2031. Assuming all patients are diagnosed and treatment is prioritized in F3 and F4 using highly efficacious direct-acting antiviral (DAA) regimens, a 69.85% reduction in ESLD incidence is predicted between 2015 and 2035, and the cumulative discounted medical expenditure associated with the lifetime management of incident ESLD events is estimated to be £1,202,827,444.

CONCLUSIONS

The prevalence of chronic hepatitis C is expected to fall in coming decades; however, the ongoing financial burden is expected to be high due to an increase in ESLD incidence. This study highlights the significant costs of managing ESLD that are likely to be incurred without the employment of effective treatment approaches.

Genetic factors that affect nonalcoholic fatty liver disease: A systematic clinical review

AIM: To investigate roles of genetic polymorphisms in non-alcoholic fatty liver disease (NAFLD) onset, severity, and outcome through systematic literature review.

METHODS: The authors conducted both systematic and specific searches of PubMed through December 2015 with special emphasis on more recent data (from 2012 onward) while still drawing from more historical data for background. We identified several specific genetic polymorphisms that have been most researched and, at this time, appear to have the greatest clinical significance on NAFLD and similar hepatic diseases. These were further investigated to assess their specific effects on disease onset and progression and the mechanisms by which these effects occur.

RESULTS: We focus particularly on genetic polymorphisms of the following genes: PNPLA3, particularly the p. I148M variant, TM6SF2, particularly the p. E167K variant, and on variants in FTO, LIPA, IFNλ4, and iron metabolism, specifically focusing on HFE, and HMOX-1. We discuss the effect of these genetic variations and their resultant protein variants on the onset of fatty liver disease and its severity, including the effect on likelihood of progression to cirrhosis and hepatocellular carcinoma. While our principal focus is on NAFLD, we also discuss briefly effects of some of the variants on development and severity of other hepatic diseases, including hepatitis C and alcoholic liver disease. These results are briefly discussed in terms of clinical application and future potential for personalized medicine.

CONCLUSION: Polymorphisms and genetic factors of several genes contribute to NAFLD and its end results. These genes hold keys to future improvements in diagnosis and management.

HLA-B18 as a risk factor of short-term progression to severe liver fibrosis in HIV/HCV co-infected patients with absent or minimal fibrosis: implications for timing of therapy

Our aim was to analyze the influence of HLA-B haplotypes on liver fibrosis progression in HIV/hepatitis C virus (HCV) co-infected patients. Retrospective longitudinal study including HIV/HCV, non-cirrhotic and HCV treatment-naïve patients. The main outcome variable was liver fibrosis progression of at least one stage. One hundred and four patients constituted the study population (F0-F1: 62 (59.6%); F2: 22 (21.2%); F3: 20 (19.2%)). During a median follow-up of 54.5 months (IQR: 26.2-77), 45 patients (43.3%) showed an increase in the stage of liver fibrosis (time to event: 29 (IQR: 14-49.5) months). HLA-B18^pos patients more frequently had a higher and faster fibrosis progression rate (73.3%; 24 (IQR: 8-29) months) than HLA-B18^neg patients (38.2%; 34.5 (IQR: 14.7-51.2) months). This association was also observed in the development of F3-F4 fibrosis among F0-F2 patients (HLA-B18^pos: 69.2%; 18 (6.5-37) months vs HLA-B18^neg: 28.2%; 37 (IQR: 19-52) months). These results could impact the timing of HCV therapy in F0-F2 patients.

HLA class II alleles in Romanian patients with chronic hepatitis C

INTRODUCTION

The objective of the study was to determine the association of host human leukocyte antigen (HLA) class II genotype DRB1 alleles with the response to interferon therapy, viral loads and extent of liver fibrosis in a group of Romanian patients diagnosed with chronic hepatitis C, with different clinical outcomes. Class II HLA genes, particularly the HLA-DRB1 and DQB1 genes, have been shown to have an important role in self-limiting or persistent viral infection, in different genetic populations. In chronic hepatitis C both susceptible and protective alleles have been described, influencing the development of autoimmunity and progression to cirrhosis and hepatocellular carcinoma.

METHODS

The study included 54 patients diagnosed with chronic hepatitis C, registered and monitored from January 2014 to January 2015 at the Clinical Hospital of Infectious Diseases, Constanţa, Romania. The selected patients were positive for anti-HCV antibodies and HCV-RNA, with screening laboratory results indicating HCV genotype 1b. The method used for the assignment of alleles at HLA-DRB1 and DQB1 loci was molecular genotyping, by the sequence specific oligonucleotide (SSO) hybridization method, and when required, by the sequence specific primers method (SSP). The presence of different alleles in patients has been analyzed for statistical significance.

RESULTS

The presence of HLA-DRB1*0301 had a high frequency (14.8%) in null-responders (NR) while alleles DRB1*0701 (11.1%), DRB1*11# (22.2%) and DRB1*0101 (16.7%) were prevalent in sustained virologic responders (SVR). No significant correlation was found between the presence of HLA-DRB1* alleles and viral loads or liver fibrosis with p values not statistically significant after the Bonferroni correction.

CONCLUSION

The presented data suggest that in this group of Romanian patients, certain HLA alleles influence the therapeutic response in HCV infection and genetic predisposition may play a role in hepatitis C virus infection in those patients.

Interferon-λ rs12979860 genotype and liver fibrosis in viral and non-viral chronic liver disease

Tissue fibrosis is a core pathologic process that contributes to mortality in ~45% of the population and is likely to be influenced by the host genetic architecture. Here we demonstrate, using liver disease as a model, that a single-nucleotide polymorphism (rs12979860) in the intronic region of interferon-λ4 (IFNL4) is a strong predictor of fibrosis in an aetiology-independent manner. In a cohort of 4,172 patients, including 3,129 with chronic hepatitis C (CHC), 555 with chronic hepatitis B (CHB) and 488 with non-alcoholic fatty liver disease (NAFLD), those with rs12979860CC have greater hepatic inflammation and fibrosis. In CHC, those with rs12979860CC also have greater stage-constant and stage-specific fibrosis progression rates (P<0.0001 for all). The impact of rs12979860 genotypes on fibrosis is maximal in young females, especially those with HCV genotype 3. These findings establish rs12979860 genotype as a strong aetiology-independent predictor of tissue inflammation and fibrosis.

Protective effect of HLA-DRB1 11 and predisposition of HLA-C 04 in the development of severe liver damage in Brazilian patients with chronic hepatitis C virus infection

The objective of this study was to investigate human leucocyte antigen (HLA) genes in patients chronically infected with hepatitis C virus (HCV) and to analyse the possible role of these genes in the progression of chronic hepatitis C. One hundred and forty-five (145) Brazilian patients infected only with HCV genotype 1 were evaluated. HLA class I (A, B, C) and class II (DRB1, DQA1, DQB1) typing were carried out by PCR-SSO, through Luminex technology. Associations were found with protection against development of liver damage by both DRB1 11 (5.0% versus 18.2%, P=0.0016, OR=0.23, CI 95% = 0.09-0.58; Pc=0.0208) and DRB1 11-DQA1 05-DQB1 03 haplotype (4.2% versus 15.3%, P=0.0032; OR = 0.24, CI 95% = 0.08-0.64). Liver damage was associated with HLA-C 04 in patients with <20 years of infection (38.4% versus 9.1%, P = 0.002, OR = 6.25, CI 95%=1.97-19.7; Pc=0.0238). It is concluded that HLA alleles can influence the development of liver damage in HCV type-1 chronically infected Brazilian patients.

The relation of HLA genotype to hepatitis C viral load and markers of liver fibrosis in HIV-infected and HIV-uninfected women

BACKGROUND

Human leukocyte antigen (HLA) class I and II genotype is associated with clearance of hepatitis C virus (HCV) infection, but little is known regarding its relation with HCV viral load or risk of liver disease in patients with persistent HCV infection.

METHODS

High-resolution HLA class I and II genotyping was conducted in a prospective cohort of 519 human immunodeficiency virus (HIV)-seropositive and 100 HIV-seronegative women with persistent HCV infection. The end points were baseline HCV viral load and 2 noninvasive indexes of liver disease, fibrosis-4 (FIB-4), and the aspartate aminotransferase to platelet ratio index (APRI), measured at baseline and prospectively.

RESULTS

DQB1*0301 was associated with low baseline HCV load (β = -.4; 95% confidence interval [CI], -.6 to -.3; P < .00001), as well as with low odds of FIB-4-defined (odds ratio [OR], .5; 95% CI, .2-.9; P = .02) and APRI-defined liver fibrosis (OR, .5; 95% CI, .3-1.0; P = .06) at baseline and/or during follow-up. Most additional associations with HCV viral load also involved HLA class II alleles. Additional associations with FIB-4 and APRI primarily involved class I alleles, for example, the relation of B*1503 with APRI-defined fibrosis had an OR of 2.0 (95% CI, 1.0-3.7; P = .04).

CONCLUSIONS

HLA genotype may influence HCV viral load and risk of liver disease, including DQB1*0301, which was associated with HCV clearance in prior studies.

Liver fibrogenesis and genetic factors

Chronic liver diseases lead to the accumulation of fibrosis in the liver with eventual progression to cirrhosis and its complications. However, there is a wide range of inter-individual variation in the liver fibrogenesis process, thus posing a challenge to physicians to identify patients with poor prognosis. As demographic and environmental factors only account for a small portion of fibrogenesis variability, host genetic factors have been suggested as playing an important role. Due to technical limitations, the first genetic studies were restricted to the evaluation of candidate genes having a known or supposed function in liver fibrogenesis. Recently, technological improvements have made it possible to study the whole human genome in a single scan. Genome-wide association studies have considerably heightened the interest in genetics as part of the study of liver fibrogenesis through their identification of previously unsuspected genes that are statistically associated with liver fibrosis. It is thus possible to determine new diagnostic or prognostic genetic markers for the management of patients with chronic liver diseases. Moreover, functional analyses of these genes may provide new insights into the pathophysiology of liver fibrogenesis.

Genes and hepatitis C: susceptibility, fibrosis progression and response to treatment

Hepatitis C virus contact and infection show three different phenotypes: spontaneous viral clearance (SVC), chronic hepatitis C (CHC) and sustained virological response (SVR) following antiviral treatment. Many factors, including genetics, influence the evolution of these three phenotypes. We performed a literature search (PubMed) up to 31 January 2010 without language restriction to identify relevant studies on genes and hepatitis C. Additional studies were sought by reviewing the reference lists of the identified articles. Meta-analysis (using Meta-disk 1.4) was conducted to evaluate the association of single nucleotide polymorphism (SNP) in the IL28B region and SVR. The candidate gene approach showed strong relationships between human leucocyte antigen class II (DQB1(*) 0301 and DRB1(*) 1101) and SVC. A cirrhosis risk score involving 7 SNPs has been validated recently. The set of odds ratios of studies demonstrated an association between SNP (rs12987960/rs8099917) in the IL28B and SVR in CHC treated with peginterferon plus ribavirin (OR: 4.6; 95% CI: 2.9-7.3). The overall distribution of protective allele correlated with ethnic differences in SVR (Asians, Europeans, Hispanic and Afro-Americans) together with SVC, but not with fibrosis stage or viral load. These polymorphisms did not influence SVR in very-easy-to-treat patients such as genotype 2/3, rapid virological responders or patients with acute hepatitis C. While the genetic fingerprint for fibrosis progression remains elusive, IL28b polymorphism predicts SVC and SVR. However, nearly half of patients achieving SVR did not show favourable genotype. Further genetic signals are warranted to complete the puzzle of factors influencing hepatitis C.

Association of human leucocyte antigen Class I (HLA-A and HLA-B) with chronic hepatitis C virus infection in Egyptian patients

Egypt has the highest prevalence of hepatitis C virus (HCV) in the world, ranging from 6% to 28% with an average of approximately 13.8% in the general population. It has been reported that human leucocyte antigen (HLA) alleles are associated with the outcome of HCV infection, but this associations showed ethnic and geographical differences. The objective of this study is to investigate the association between the frequencies of HLA Class I and chronic HCV infection in Egyptian patients and to find out whether there is a relation between certain HLA Class I antigens and HCV viral load, degree of fibrosis, activity and alanine aminotransferase (ALT) level. A case control study was conducted on 100 patients with chronic HCV infection and 150 healthy controls. HLA-A and HLA-B typing by complement-dependent micro-lympho-cytotoxicity assay was performed for both groups. HLA-A11 antigen was significantly increased in patients with chronic HCV infection versus controls (OR 3.98; 95% CI = 1.85-8.89; P = 0.001; and Pc = 0.021). HLA-B12, HLA-B13, HLA-B17 and HLA-B40 were higher in patients, and HLA-A32 and HLA-B14 were higher in controls, although the significance was lost after correction for multiple testing. HLA-A9 was significantly associated with low viral load (P = 0.008, Pc = 0.048). The results of this work implicate that HLA-A11 antigen may influence chronic HCV infection and may play a role in viral persistence. Different HLA Class I antigens are not associated with degree of liver fibrosis, grades of activity or level of ALT. However, HLA-A9 is associated with low HCV viral load in chronic HCV Egyptian patients.

Influence of selected HLA tissue compatibility antigens on the course and efficacy of viral hepatitis C treatment--actual knowledge position

Hepatitis C virus (HCV) infection is a common problem. Combined treatment with interferon and ribavirin improved treatment efficacy, but still high percentage of infected patients has not reached virus elimination. It was found that HCV infection course, but also treatment efficacy among other things can depend on patient's individual factors, including MHC genes structure for HLA tissue compatibility antigens. Many connections between HLA system and HCV infection course were noted. There are some reports concerning connections between MHC structure and results of chronic hepatitis C treatment with interferon. In future, results of investigations connected with this problem can allow to verify qualification criteria for treatment with alpha-interferon, because actual knowledge position has been too inconspicuous to have practical significance.

Narcotic analgesics and progression of fibrosis in patients with chronic hepatitis C

Narcotic analgesics are commonly prescribed drugs in patients with chronic hepatitis C (CHC) infection. In vitro data have shown that morphine enhances hepatitis C virus replication in human hepatic cells, however the effect of narcotics on hepatitis C virus disease progression remains uncertain. The aim of this study was to evaluate the potential effects of narcotic analgesic use on the progression of hepatic fibrosis in patients with CHC infection. We identified CHC patients who had been seen at our institution and had undergone a liver biopsy between 1990 and 2005. Their charts were reviewed for the presence of narcotic analgesic and known risk factors for progression of hepatic fibrosis including male sex, age > or =40, obesity, diabetes, and alcohol abuse. All biopsy were reviewed and fibrosis scores were standardized using the Batts and Ludwig scoring system (stage 0 to 4). A total of 1147 evaluable patients were identified and 171 of these had narcotic analgesic use. In univariate analysis, narcotic analgesic use was associated with the presence of alcohol abuse (P<0.001), obesity (P=0.02), and advanced fibrosis defined as stage 3 to 4 fibrosis (P=0.02), but not with male sex or diabetes. In multivariate logistic regression analysis, obesity [odds ratio (OR) 1.68 (confidence interval (CI), 1.21-2.33)], alcohol abuse [OR 1.45 (CI, 1.04-2.02)], age > or =40 [OR 1.85 (CI, 1.22-2.89)], and diabetes [OR 2.43 (CI, 1.41-4.14)] all independently predicted advanced liver fibrosis but narcotic analgesic use did not [OR 1.71 (CI, 0.99-2.89)]. As the amount of narcotic analgesic use increased from no use, to <3 months use, to > or =3 months use, the frequency of obesity, alcohol abuse, and advanced fibrosis increased accordingly (P=0.005), suggesting that it is difficult to separate these known risk factors from narcotic use as the cause for advanced fibrosis in this population.

Genesis of hepatic fibrosis and its biochemical markers

Liver fibrosis is characterized by an abnormal hepatic accumulation of extracellular matrix (ECM) that results from both increased deposition and reduced degradation of collagen fibres. Fibrotic liver injury results in activation of the hepatic stellate cell (HSC). Surrogate markers are gradually being substituted for biomarkers that reflect the complex balance between synthesis and degradation of the extracellular matrix. Once the hepatic stellate cell is activated, the preceding matrix changes and recurrent injurious stimuli will perpetuate the activated state. The ECM directs cellular differentiation, migration, proliferation and fibrogenic activation or deactivation. The metabolism of the extracellular matrix is closely regulated by matrix metalloproteinases (MMP) and their specific tissue inhibitors (TIMP). Although liver biopsy combined with connective tissue stains has been a mainstay of diagnosis, there is a need for less invasive methods. These diagnostic markers should be considered in combination with liver function tests, ultrasonography and clinical manifestations.

The association between the genetic polymorphism of HLA-DQA1, DQB1, and DRB1 and serum alanine aminotransferase levels in chronic hepatitis C in the Chinese population

BACKGROUND AND AIM

To investigate a possible association between HLA genes with serum alanine aminotransferase (ALT) levels and evaluate whether the HLA-DQA1, DQB1, and DRB1 genes could influence the development of liver damage in chronic hepatitis C.

METHODS

A total of 145 patients with chronic hepatitis C virus (HCV) infection (36 patients with persistently normal ALT values; 109 patients with elevated ALT levels) and 160 uninfected healthy controls were examined for HLA-DQA1, DQB1, and DRB1 molecules by using polymerase chain reaction-sequencing based typing (PCR-SBT).

RESULTS

Among the patients chronically infected with HCV, the frequencies of DQA1*0501, DQB1*0301, and DRB1*0401 alleles were significantly increased in the normal ALT group compared with those with abnormal ALT levels, whereas that of DQB1*0201 was significantly lower. As compared to uninfected healthy controls, DQA1*0501, DQB1*0301, and DRB1*0401 allele frequencies were also statistically higher in the normal ALT group, whereas that of DQB1*0201 was the inverse. The haplotype frequencies of DQA1*0301-DQB1*0301, DQA1*0501-DQB1*0301, and DRB1*1101-DQB1*0301 were found to be significantly higher in the normal ALT group. Multivariate logistic regression indicated that female sex, and the DQB1*0301 allele and DRB1*0401 allele were independently associated with normal ALT values, whereas DQB1*0201 allele was the inverse.

CONCLUSIONS

These results suggest that particular HLA alleles may have an influence on the serum ALT level of chronic HCV infection as a host genetic factor in the Chinese population. The DQA1*0501, DQB1*0301, and DRB1*0401 alleles, and the DQA1*0301-DQB1*0301, DQA1*0501-DQB1*0301, and DRB1*1101-DQB1*0301 haplotypes seem to be associated with low hepatitis activity; whereas DQB1*0201 allele is closely correlated with the progression of liver injury in chronic HCV infection.

Host genetic factors and antiviral immune responses to hepatitis C virus

Human genome variations explain some of the heterogeneity in the immune response to antigenic stimuli. Such differences in response to hepatitis C virus (HCV) antigens can account for the ability of the immune response to clear HCV after an acute infection or to develop more rapidly progressive liver disease. Several studies have examined polymorphisms in several candidate immune-response genes for their relation to these HCV outcomes. Results of some of these studies complement knowledge gained from immunology studies, and others offer new insights into HCV biology. This review summarizes published studies on variation in immune-response genes and HCV outcomes.

Therapy with interferon-alpha and ribavirin for chronic hepatitis C virus infection upregulates membrane HLA-ABC, CD86, and CD28 on peripheral blood mononuclear cells

Multiple interferon-stimulated genes (ISGs) involving T-cell activation are upregulated during initial interferon-alpha-based therapy for chronic hepatitis C virus (HCV) infection. However, the long-term impact on therapeutic outcome in patients remains unknown. In this study, the effects of anti-HCV therapy on the surface expression of HLA-ABC, CD86, and CD28 were longitudinally assessed. These proteins are integral membrane receptors of antigen presentation and triggering of costimulatory signals for activating CD8+ T cells. Peripheral blood mononuclear cells were collected at baseline and post-treatment for 1 day, and 2, 4, 12, and 24 weeks, respectively. This treatment led to a time-related elevation of membrane levels of HLA-ABC and CD86 on B-cells and monocytes in patients with a sustained response (n = 23), but not in those without (n = 8). Meanwhile, upregulation of CD28 on CD4+ and CD8+ T cells was comparable in both groups of sustained responders and non-responders. Steady increases in the B cells' surface and intracellular HLA-ABC were observed, thus, the surface-to-intracellular ratios did not alter over the period of treatment. Furthermore, multivariate analysis shows that increased HLA-ABC on monocytes by week 12 correlates significantly with sustained response (P = 0.033). In conclusion, differential modulation of T-cell activation ISGs, such as HLA-ABC and CD86 might correlate with the outcome of interferon-alpha-based therapy in chronic hepatitis C patients.

Hla-Cw7 allele as predictor of favorable therapeutic response to interferon-alpha in patients with chronic hepatitis C

AIM

To evaluate the association between human leukocyte antigens (HLA) class I and therapeutic response to interferon-alpha in Croatian patients with chronic hepatitis C.

METHODS

HLA-A, -B, and -C genotyping was performed in 55 patients with sustained virological response and in 57 patients without sustained virological response to interferon-alpha therapy. Patients were treated in the period from 1998-2001 with interferon-alpha at a dose of 3 million units three times a week. Patients who became negative for hepatitis C virus RNA after 12 weeks of therapy completed 48 weeks of therapy.

RESULTS

There was no association between therapeutic outcome and frequency of HLA-A, as well as of HLA-B alleles. HLA-Cw7 was significantly more frequent in patients with than those without sustained virological response (27.0% vs 6.7%; P=0.011).

CONCLUSION

In Croatian patients with chronic hepatitis C, HLA-Cw7 is the predictor of sustained virological response to interferon-alpha therapy.

Evidence for human leukocyte antigen heterozygote advantage against hepatitis C virus infection

Outcomes of infection with hepatitis C virus (HCV) vary widely, from asymptomatic clearance to chronic infection, leading to complications that include fibrosis, cirrhosis, hepatocellular carcinoma, and liver failure. Previous studies have reported statistical associations between human leukocyte antigen (HLA) heterozygosity and favorable outcomes of infection with either hepatitis B virus (HBV) or human immunodeficiency virus (HIV) (the "heterozygote advantage"). To investigate whether HLA zygosity is associated with outcome of HCV infection, we used data from the United States Organ Procurement and Transplantation Network database of 52,435 liver transplant recipients from 1995 through 2005. Of these, 30,397 were excluded for lack of HLA data, retransplantation, known HIV infection, or insufficient information regarding HBV infection. The remaining cases were analyzed for associations between HCV infection and HLA zygosity with 1-sided Fisher's exact tests. Results show significantly lower proportions of HLA-DRB1 heterozygosity among HCV-infected than uninfected cases. The differences were more pronounced with alleles represented as functional supertypes (P = 1.05 x 10(-6)) than as low-resolution genotypes (P = 1.99 x 10(-3)). No significant associations between zygosity and HCV infection were found for other HLA loci.

CONCLUSION

These findings constitute evidence for an advantage among carriers of different supertype HLA-DRB1 alleles against HCV infection progression to end-stage liver disease in a large-scale, long-term study population. Considering HLA polymorphism in terms of supertype diversity is recommended in strategies to design association studies for robust results across populations and in trials to improve treatment options for patients with chronic viral infection. Access to deidentified clinical information relating genetic variation to viral infection improves understanding of variation in infection outcomes and might help to personalize medicine with treatment options informed in part by human genetic variation.

Immunopathogenesis of hepatitis C virus infection and hepatic fibrosis: New insights into antifibrotic therapy in chronic hepatitis C

Fibrosis and cirrhosis represent the consequences of a sustained wound-healing response to chronic liver injury of any cause. Chronic hepatitis C virus (HCV) has emerged as a leading cause of cirrhosis in the USA and throughout the world. HCV may induce fibrogenesis directly by hepatic stellate cell activation or indirectly by promoting oxidative stress and apoptosis of infected cells. The ultimate result of chronic HCV injury is the accumulation of extracellular matrix with high density type I collagen within the subendothelial space of Disse, culminating in cirrhosis with hepatocellular dysfunction. The treatment of hepatitis C with the combination of pegylated interferon and ribavirin is still both problematic and costly, has suboptimal efficacy, serious side effects and a high level of intolerance, and is contraindicated in many patients. Hence, new approaches have assumed greater importance, for which there is an urgent need. The sustained progress in understanding the pathophysiology of hepatic fibrosis in the past two decades has increased the possibility of developing drugs specifically targeting the fibrogenic process. Future efforts should identify genetic markers associated with fibrosis risk in order to tailor the treatment of HCV infection based on genetically regulated pathways of injury and/or fibrosis. Such advances will expand the arsenal to overcome liver fibrosis, particularly in patients with hepatic diseases who have limited treatment options, such as those patients with chronic hepatitis C who have a high risk of fibrosis progression and recurrent HCV disease after liver transplantation.

A comparative review of HLA associations with hepatitis B and C viral infections across global populations

Hepatitis B (HBV) and hepatitis C (HCV) viral infection or co-infection leads to risk of development of chronic infection, cirrhosis and hepatocellular carcinoma (HCC). Immigration and globalization have added to the challenges of public health concerns regarding chronic HBV and HCV infections worldwide. The aim of this study is to review existing global literature across ethnic populations on HBV and HCV related human leukocyte antigen (HLA) associations in relation to susceptibility, viral persistence and treatment. Extensive literature search was conducted to explore the HLA associations in HBV and HCV infections reported across global populations over the past decade to understand the knowledge status, weaknesses and strengths of this information in different ethnic populations. HLA DR13 is consistently associated with HBV clearance globally. HLADRB1*11/*12 alleles and DQB1*0301 are associated with HBV persistence but with HCV clearance worldwide. Consistent association of DRB1*03 and *07 is observed with HCV susceptibility and non-responsiveness to HBV vaccination across the population. HLA DR13 is protective for vertical HBV and HCV transmission in Chinese and Italian neonates, but different alleles are associated with their susceptibility in these populations. HLA class I molecule interactions with Killer cell immunoglobulin like receptors (KIR) of natural killer (NK) cells modulate HCV infection outcome via regulating immune regulatory cells and molecules. HLA associations with HBV vaccination, interferon therapy in HBV and HCV, and with extra hepatic manifestations of viral hepatitis are also discussed. Systematic studies in compliance with global regulatory standards are required to identify the HLA specific viral epitope, stage specific T cell populations interacting with different HLA alleles during disease progression and viral clearance of chronic HBV or HCV infections among different ethnic populations. These studies would facilitate stage specific therapeutic strategies for clearance of HBV and HCV infections or co-infections across global populations and aid in identification of HBV-HCV combined vaccine. HLA associations of chronic HBV or HCV development with confounding host factors including alcohol, drug abuse, insulin resistance, age and gender are lacking and warrant detailed investigation across global populations.

Impact of the genetic restriction of virus-specific T-cell responses in hepatitis C virus infection

The immunobiology of hepatitis C virus (HCV) is significantly influenced by the host immune response to the virus, especially by virus-specific T-cell responses. Virus-specific T cells are restricted by human leucocyte antigen class I and II molecules. Of note, associations between these polymorphic loci and outcome and course of HCV infection have been reported in large and well-documented cohorts. This review will briefly summarize these studies and focus especially on the immunological and virological basis for the reported associations. The outcome and course of HCV infection is most likely determined by a complex interplay of genetic, immunological and virological factors. A better understanding of these host-virus interactions is essential not only to gain better insights into the mechanisms of viral clearance and persistence but also for the development of new antiviral vaccine strategies.

The changing epidemiology and natural history of hepatitis C virus infection

Injection drug use remains the predominant mode of transmission of hepatitis C virus (HCV) infection. Growing numbers of persons who have been chronically infected with HCV for 20 or more years are coming to medical attention and are at risk for serious complications of chronic infection, including cirrhosis and hepatocellular carcinoma. Factors linked with the development of advanced fibrosis and cirrhosis include age at infection, duration of infection, heavy alcohol use, coinfections with HIV or hepatitis B virus, and male sex. Emerging risk factors for disease progression include steatosis, insulin resistance (and factors associated with the metabolic syndrome), and host genetics.