Human leukocyte antigen class I and class II genes polymorphisms might be associated with interferon α therapy efficiency of chronic hepatitis B

Host Genetic Determinants of Hepatitis B Virus Infection

Chronic hepatitis B virus (HBV) infection is still a major health problem worldwide. Recently, a great number of genetic studies based on single nucleotide polymorphisms (SNPs) and genome-wide association studies have been performed to search for host determinants of the development of chronic HBV infection, clinical outcomes, therapeutic efficacy, and responses to hepatitis B vaccines, with a focus on human leukocyte antigens (HLA), cytokine genes, and toll-like receptors. In addition to SNPs, gene insertions/deletions and copy number variants are associated with infection. However, conflicting results have been obtained. In the present review, we summarize the current state of research on host genetic factors and chronic HBV infection, its clinical type, therapies, and hepatitis B vaccine responses and classify published results according to their reliability. The potential roles of host genetic determinants of chronic HBV infection identified in these studies and their clinical significance are discussed. In particular, HLAs were relevant for HBV infection and pathogenesis. Finally, we highlight the need for additional studies with large sample sizes, well-matched study designs, appropriate statistical methods, and validation in multiple populations to improve the treatment of HBV infection.

Polymorphisms of CYP27B1 are associated with IFN efficacy in HBeAg-positive patients

BACKGROUND

Host single nucleotide polymorphisms were associated with antiviral therapy in CHB patients. The CYP27B1 gene, encoding 25(OH)D₃ -1α hydroxylase, might activate 25(OH)D₃ to 1,25(OH)₂ D₃ in kidney resulted in influencing the efficacy of interferon (IFN). The aim of the study was to investigate the association between CYP27B1 polymorphisms and the response to IFN in HBeAg-positive patients.

METHODS

Eighty-seven HBeAg-positive CHB patients infected with HBV genotype B or C were included in the study. All patients were treated with IFN at least 1 year. According to the response to PEG-IFN therapy, they were divided into three groups: 16 complete responses (CR), 42 partial responses (PR), and 29 nonresponses (NR). Sanger-sequencing was utilized to genotype the CYP27B1 SNPs(rs4646536 and rs10877012).

RESULTS

In logistic regression analysis, the frequency of rs4646536 CC genotype was observed to be higher in the NR group. Besides, the GG genotype of rs10877012 differed significantly among the three groups. The GG genotype was prevalent in patients with CR, and patients with TT genotype result in NR at the end of IFN treatment. The most common haplotype TG was independently associated with CR, after adjustment, and haplotype CT appeared to be associated with NR and PR, rather than CR. The data also showed that patients with baseline 1,25(OH)₂ D₃ > 39.39 pg/mL had higher CR rates at the end of IFN therapy.

CONCLUSION

These results suggested CYP28B1 gene polymorphisms may be independently associated with the efficacy of IFN in HBeAg-positive patients.

Association of human leukocyte antigen haplotypes with clearance and persistence of hepatitis B virus infection in northeastern China

This study investigated clinical implications of human leukocyte antigen (HLA) I and II haplotypes, in combination with HBV sub-genotype C2, in hepatitis B virus (HBV) infections in northeastern China. Here, HLA haplotypes of 230 HBV-infected patients were compared to 210 healthy, unrelated Han individuals. Of the 230 HBV-infected patients, 54 had acute self-limited hepatitis (ASH) with sub-genotype C2 (ASH-C2), 144 had chronic hepatitis (CH) with sub-genotypes C2 and B2 (CH-C2 and CH-B2), and 32 spontaneously recovered without sub-genotype results. All groups underwent HLA typing and haplotype analysis. The results revealed that A*02-DRB1*12 and A*02-B*15-DRB1*09 carriers were susceptible to HBV infection. A*02-B*15-DRB1*09 is probably associated with acute onset and viral clearance and A*02-DRB1*12, with viral persistence. In HBV infections, B*40-DRB1*12 was associated with HBV persistence, whereas B*46-DRB1*09, A*24-DRB1*14, and B*15-DRB1*04 carriers easily recovered from the disease. By contrast, when infected with the HBV-C2 sub-genotype, A*24-DRB1*14, B*15-DRB1*04, A*02-B*15, A*02-DRB1*15, and A*02-B*15-DRB1*09 carriers displayed an acute clinical course before recovery. This study reveals a relationship between HLA haplotypes and HBV pathogenesis, thereby providing potential therapeutic targets to treat HBV infection.

Polymorphism of estrogen receptor alpha (ESR1) is associated with virological response to entecavir (ETV) in nucleoside-naïve adult patients with chronic hepatitis B

INTRODUCTION

Polymorphisms in estrogen receptor alpha (ESR1) are reported to be associated with the susceptibility to persistent HBV infection, HBV liver cirrhosis and HBV-related hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

To test the hypothesis that polymorphisms in estrogen receptor alpha (ESR1) might influence the virological response to entecavir (ETV) therapy, we examined two polymorphisms (PvuII and XbaI) in 76 nucleoside-naïve chronic hepatitis B (CHB) patients. All of the patients (52 HBeAg-positive and 24 HBeAg-negative) were treated with ETV 0.5 mg daily and followed up for a median time of 96 weeks (range 48-96). Polymorphisms were determined using the polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) method.

RESULTS

Under an additive model, the univariate analysis showed that patients carrying the PvuII T/C genotype might have higher virological responders than those carrying the T/T and C/C genotypes at week 48 (87.7 vs. 57.1 vs. 58.3 %; P = 0.012) and week 96 (96.7 vs. 64.3 vs. 24 87.5 %; P = 0.018), although this difference disappeared with the multiple analysis at week 48 [95 % confidence interval (CI) 0.687-3.841; P = 0.269] and week 96 (95 % CI 0.861-18.016; P = 0.077). Conversely, the univariate analysis suggests statistical significance between the recessive model of PvuII (TT vs. TC/CC) and virological response at week 48 (57.1 vs. 81.1 %; P = 0.033) and week 96 (64.3 vs. 94.7 %; P = 0.017). Multiple regression analysis affirmed the significant and independent association between the recessive model of PvuII and virological response. In other words, patients carrying at least one PvuII C allele (TC/CC) had a better likelihood of achieving virological response compared with those carrying the T/T genotype at week 48 (95 % CI 1.026-14.785, P = 0.046) and week 96 (95 % CI 1.456-57.509; P = 0.018). XbaI polymorphisms were not significantly associated with virological response.

CONCLUSION

Our results suggest that the PvuII polymorphism may play an important role in determining ETV efficacy after 48 and 96 weeks of treatment, at least in this study population.

Theoretical basis of a beneficial role for vitamin D in viral hepatitis

Abnormal bone metabolism and dysfunction of the calcium-parathyroid hormone-vitamin D axis have been reported in patients with viral hepatitis. Some studies suggested a relationship between vitamin D and viral hepatitis. Genetic studies have provided an opportunity to identify the proteins that link vitamin D to the pathology of viral hepatitis (i.e., the major histocompatibility complex class II molecules, the vitamin D receptor, cytochrome P₄₅₀, the renin-angiotensin system, apolipoprotein E, liver X receptor, toll-like receptor, and the proteins regulated by the Sp1 promoter gene). Vitamin D also exerts its effects on viral hepatitis via non-genomic factors, i.e., matrix metalloproteinase, endothelial vascular growth factor, prostaglandins, cyclooxygenase-2, and oxidative stress. In conclusion, vitamin D could have a beneficial role in viral hepatitis. Calcitriol is best used for viral hepatitis because it is the active form of the vitamin D₃ metabolite.

Polymorphisms in ADAR1 gene affect response to interferon alpha based therapy for chronic hepatitis B in Han Chinese

Host genetic polymorphisms in interferon pathway genes are reported to be associated with response to interferon therapy. Five hundred and forty-eight α interferon treatment-naïve chronic hepatitis B patients were enrolled in the retrospective nested case-control study. All patients received α interferon based treatment and were examined for therapy efficacy. We genotyped 115 polymorphisms from 16 interferon pathway genes using the MassArray system. We identified rs4845384 in ADAR1 gene is strongly associated with the outcome of interferon therapy allele dose-depended (P=0.0005), with decreased odds ratios of 0.69 and 0.27 for GA and AA genotypes, respectively (95% confidence interval, 0.47-0.99 for GA; 0.11-0.64 for AA). Our study suggested that rs4845384 in ADAR1 associates with treatment-induced clearance of chronic hepatitis B.