Relationship between HLA-DR gene polymorphisms and outcomes of hepatitis B viral infections: A meta-analysis

Genetic variation of TLR3 gene is associated with the outcome of hepatitis b infection in mauritanian patients: case control study

BACKGROUND

Toll-Like receptors (TLRs) play an important role in the immune response during hepatitis B virus (HBV) infection. In this study, we evaluated the association between two SNP variants (TLR3 rs3775290 and TLR4 rs4986790) and susceptibility to chronic HBV infection in Mauritania.

SUBJECTS AND METHODS

A total of 188 subjects were recruited for this study: 102 chronically infected patients and 86 individuals with spontaneously resolved HBV infection who were considered controls. Targeted PCR products were sequenced using Sanger sequencing.

RESULTS

We found that TLR3 rs3775290 was significantly more frequent in patients with chronic HBV than in the control population (p = 0.03). However, no association was found between the TLR4 rs3775290 polymorphism and chronic infection.

CONCLUSION

Our results suggest that the TLR3 rs3775290 polymorphism may be a risk factor for susceptibility to chronic HBV infection in the Mauritanian population.

Epstein-Barr virus-acquired immunodeficiency in myalgic encephalomyelitis-Is it present in long COVID?

Both myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS) and long COVID (LC) are characterized by similar immunological alterations, persistence of chronic viral infection, autoimmunity, chronic inflammatory state, viral reactivation, hypocortisolism, and microclot formation. They also present with similar symptoms such as asthenia, exercise intolerance, sleep disorders, cognitive dysfunction, and neurological and gastrointestinal complaints. In addition, both pathologies present Epstein-Barr virus (EBV) reactivation, indicating the possibility of this virus being the link between both pathologies. Therefore, we propose that latency and recurrent EBV reactivation could generate an acquired immunodeficiency syndrome in three steps: first, an acquired EBV immunodeficiency develops in individuals with "weak" EBV HLA-II haplotypes, which prevents the control of latency I cells. Second, ectopic lymphoid structures with EBV latency form in different tissues (including the CNS), promoting inflammatory responses and further impairment of cell-mediated immunity. Finally, immune exhaustion occurs due to chronic exposure to viral antigens, with consolidation of the disease. In the case of LC, prior to the first step, there is the possibility of previous SARS-CoV-2 infection in individuals with "weak" HLA-II haplotypes against this virus and/or EBV.

Association of DRB1*11 and DRB1*12 alleles of the HLA system with the evolution of the Hepatitis B virus infection in Burkina Faso

BACKGROUND

Hepatitis B Virus (HBV) infection affect all social strata of humanity and in the absence of any management, this infection has a different outcome from one infected person to another. This suggests that there are specific individual factors that influence the outcome of the pathology. Sex, immunogenetics and age of contraction of the virus have been cited as factors that influence the evolution of the pathology. In this study, we looked at two alleles of the Human Leucocyte Antigen (HLA) system to measure their possible involvement in the evolution of HBV infection.

METHOD AND RESULTS

We conducted a cohort study involving 144 individuals spread over 04 distinct stages of infection and then compared allelic frequencies in these populations. A multiplex PCR was conducted and the data obtained was analyzed using R and SPSS software. Our study revealed a predominance of HLA-DRB1*12 in our study population without, however, showing a significant difference between HLA-DRB1*11 and HLA-DRB1*12. The HLA-DRB1*12 proportion was significantly higher in chronic hepatitis B (CHB) and resolved hepatitis B (RHB) compared to cirrhosis and hepatocellular carcinoma (HCC) (p-value = 0,002). Carrying HLA-DRB1*12 has been associated with a low risk of complication of infection (CHB → cirrhosis; OR 0,33 p-value 0,017; RHB → HCC OR 0,13; p-value = 0,00,045) whereas the presence of HLA-DRB1*11 in the absence of HLA-DRB1*12 increased the risk of developing severe liver disease. However, a strong interaction of these alleles with the environment could modulate the infection.

CONCLUSION

Our study shown that HLA-DRB1*12 is the most frequent and it's carriage may be protective in the development of infection.

Association of HLADQ-B1 polymorphisms in three generations of chronic hepatitis B patients

The presence of polymorphisms in the human leukocyte antigen (HLA)-DQB1 gene, along with its expression, has been demonstrated to be correlated with spontaneous clearance and susceptibility to HBV infection. The present study aimed to evaluate the possible role of genetic polymorphisms in HLA-DQB1 in three generations of patients with chronic hepatitis B (CHB). Based on the inclusion criteria, 90 CHB patients, 18 individuals recovered from HBV infection, and 40 healthy subjects were chosen. The DNA contents of the whole blood samples were extracted in order to perform HLA-DQB1 typing by the PCR technique. Besides whole blood samples, sera were applied to measure liver function tests (LFTs), as well as the titers of anti-HDV and anti-HCV. Also, in all CHB patients were measured liver stiffness (LSM) by Fibro Scan. The results of HLA-DQB1 polymorphisms (rs2856718 and rs7453920) demonstrated that the majority of polymorphisms in CHB patients were HLA-DQB1*03, HLA-DQB1*05, HLA-DQB1*04:01 and HLA-DQB1*03:01 that associated with HBV persistence and chronicity. Among the patients who showed these polymorphisms, the mean±SD, LSM was 4±1.57 KPa and most of them, F grade was reported as F2, which was a sign of disease progression towards chronicity. HLA polymorphisms imputation revealed that HLA-DQB1*06:04 (3.4%, P-Value= 0.2) was detected only in healthy subjects as protective polymorphism, while the allele HLA-DQB1*03:03 was reported in both healthy subjects (P-Value= 0.06) and recovered patients (P-Value= 0.1) as suppressor of CHB formation. The allele HLA-DQB1*05:02 was found in both healthy subjects (3.4%) and CHB patients (4.5%) which was associated with risk to liver cirrhosis (P-Value= 0, OR: 0.002 0.95CI: 0.000-0.15). HLA polymorphism analysis indicated that 17.39% of patients who were seropositive for anti-HCV carried the HLA-DQB1*03:01. HBV resistance or infection risk could be assessed by DBQ1 typing. The existence of polymorphisms in HLA gene could influence the clearance (HLA-DQB1*03:03) or susceptibility and persistence of infection (HLA-DQB1*03, HLA-DQB1*05, HLA-DQB1*04:01 and HLA-DQB1*03:01). These results have the potential to improve personalized therapy and prognosis for HBV infection.

Genetic polymorphism of HLA-DRA and alcohol consumption affect hepatitis development in the Korean population

BACKGROUND

Hepatitis is an inflammation of the liver that has several potential causes; however, the genetic association has recently begun to be studied.

OBJECTIVES

Human leukocyte antigen (HLA) is an essential component of the immune response, and in this study, we conducted a correlation analysis to determine whether genetic polymorphisms of HLA and drinking habits affect hepatitis development.

METHODS

Genetic polymorphisms of HLA were investigated using Korean genomic and epidemiological data. A gene association study was performed using PLINK version 1.07. Other statistical analyses and multivariate logistic regression analyses were performed using PASW Statistics version 18.0.

RESULTS

Thirteen single nucleotide polymorphisms (SNPs) in HLA-DRA showed significant statistical correlations with hepatitis. In particular, rs9268645 showed the highest statistical association with hepatitis (P = 3.97 × 10^-5, odds ratio [OR] = 0.72, 95% confidence interval [CI] = 0.61-0.84). In multivariate logistic regression analysis, when considering only genetic factors, the A allele of rs9268644 showed a reduced hepatitis OR of approximately 0.52-fold. However, the group carrying the minor A allele (AA + AC) with alcohol consumption had an approximately 1.58-fold OR of hepatitis compared to that of the group carrying the same allele with no alcohol consumption. This implies that the A allele of rs9268644 has a protective effect on hepatitis by genetic factors and shows sensitivity to alcohol.

CONCLUSIONS

Our results showed that hepatitis is influenced by both genetic and external factors (drinking habits), which can provide new guidelines for the prevention or treatment of hepatitis.

The Association between Regulatory T Cell Subpopulations and Severe Pneumonia Post Renal Transplantation

Severe pneumonia accounts for the majority of morbidity and mortality in renal allograft recipients due to immunosuppressant maintenance. Regulatory T cells (Tregs), which are involved in tackling infections under immunosuppressive conditions, are rarely uncovered. We aimed to investigate the relationship between various Treg subpopulations and severe pneumonia after kidney transplantation (KTx). KTx recipients with pneumonia were divided into severe pneumonia and mild pneumonia groups. The frequencies and absolute numbers (Ab No.) of total Tregs (CD4+CD25+FoxP3+), six subsets of Tregs (Helios+/-, CD39+/-, and CD45RA+/-), and T cells, B cells, and NK cells were assessed from peripheral blood via flow cytometry using the $t$ or Mann-Whitney test and receiver operating curve analysis. We also determined the median fluorescence intensity (MFI) of human leukocyte antigen- (HLA-) DR on monocytes and CD64 on neutrophils. Logistic regression was used to identify the risk factors of disease progression, and Pearson’s correlation analysis was performed to identify relationships between the measured immune indices and patients’ clinical information. Our research indicated that Treg subpopulations were strongly associated with severe pneumonia progression post KTx. Based on the monitoring of Treg subpopulations, better-individualized prevention and therapy might be achieved for patients with severe pneumonia post KTx.

Characterization of a library of 20 HBV-specific MHC class II-restricted T cell receptors

CD4⁺ T cells play an important role in the immune response against cancer and infectious diseases. However, mechanistic details of their helper function in hepatitis B virus (HBV) infection in particular, or their advantage for adoptive T cell therapy remain poorly understood as experimental and therapeutic tools are missing. Therefore, we identified, cloned, and characterized a comprehensive library of 20 MHC class II-restricted HBV-specific T cell receptors (TCRs) from donors with acute or resolved HBV infection. The TCRs were restricted by nine different MHC II molecules and specific for eight different epitopes derived from intracellularly processed HBV envelope, core, and polymerase proteins. Retroviral transduction resulted in a robust expression of all TCRs on primary T cells. A high functional avidity was measured for all TCRs specific for epitopes S17, S21, S36, and P774 (half-maximal effective concentration [EC₅₀] <10 nM), or C61 and preS9 (EC₅₀ <100 nM). Eight TCRs recognized peptide variants of HBV genotypes A to D. Both CD4⁺ and CD8⁺ T cells transduced with the MHC II-restricted TCRs were polyfunctional, producing interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-2, and granzyme B (GrzB), and killed peptide-loaded target cells. Our set of MHC class II-restricted TCRs represents an important tool for elucidating CD4⁺ T cell help in viral infection with potential benefit for T cell therapy.

In Vivo Lentiviral Gene Delivery of HLA-DR and Vaccination of Humanized Mice for Improving the Human T and B Cell Immune Reconstitution

Humanized mouse models generated with human hematopoietic stem cells (HSCs) and reconstituting the human immune system (HIS-mice) are invigorating preclinical testing of vaccines and immunotherapies. We have recently shown that human engineered dendritic cells boosted bonafide human T and B cell maturation and antigen-specific responses in HIS-mice. Here, we evaluated a cell-free system based on in vivo co-delivery of lentiviral vectors (LVs) for expression of a human leukocyte antigen (HLA-DRA*01/ HLA-DRB1*0401 functional complex, “DR4”), and a LV vaccine expressing human cytokines (GM-CSF and IFN-α) and a human cytomegalovirus gB antigen (HCMV-gB). Humanized NOD/Rag1^null/IL2Rγ^null (NRG) mice injected by i.v. with LV-DR4/fLuc showed long-lasting (up to 20 weeks) vector distribution and expression in the spleen and liver. In vivo administration of the LV vaccine after LV-DR4/fLuc delivery boosted the cellularity of lymph nodes, promoted maturation of terminal effector CD4⁺ T cells, and promoted significantly higher development of IgG⁺ and IgA⁺ B cells. This modular lentigenic system opens several perspectives for basic human immunology research and preclinical utilization of LVs to deliver HLAs into HIS-mice.

CD4+ T Cells in Chronic Hepatitis B and T Cell-Directed Immunotherapy

The impaired T cell responses observed in chronic hepatitis B (HBV) patients are considered to contribute to the chronicity of the infection. Research on this impairment has been focused on CD8⁺ T cells because of their cytotoxic effector function; however, CD4⁺ T cells are crucial in the proper development of these long-lasting effector CD8⁺ T cells. In this review, we summarize what is known about CD4⁺ T cells in chronic HBV infection and discuss the importance and opportunities of including CD4⁺ T cells in T cell-directed immunotherapeutic strategies to cure chronic HBV.

The influence of HLA genotype on the severity of COVID-19 infection

The impact of COVID‐19 varies markedly, not only between individual patients but also between different populations. We hypothesised that differences in HLA genes might influence this variation. Using next generation sequencing, we analysed the class I and class II classical HLA genes of 147 individuals of European descent experiencing variable clinical outcomes following COVID‐19 infection. Forty‐nine of these patients were admitted to hospital with severe respiratory disease. They had no significant pre‐existing comorbidities. We compared the results to those obtained from a group of 69 asymptomatic hospital workers who evidence of COVID exposure based on blood antibody testing. Allele frequencies in both the severe and asymptomatic groups were compared to local and national healthy controls with adjustments made for age and sex. With the inclusion of hospital staff who had reported localised symptoms only (limited to loss of smell/taste, n = 13) or systemic symptoms not requiring hospital treatment (n = 16), we carried out ordinal logistic regression modelling to determine the relative influence of age, BMI, sex and the presence of specific HLA genes on symptomatology. We found a significant difference in the allele frequency of HLA‐DRB1*04:01 in the severe patient compared to the asymptomatic staff group (5.1% vs. 16.7%, P = .003 after adjustment for age and sex). There was a significantly lower frequency of the haplotype DQA1*01:01‐DQB1*05:01‐DRB1*01:01 in the asymptomatic group compared to the background population (P = .007). Ordinal logistic regression modelling confirmed the significant influence of DRB1*04:01 on the clinical severity of COVID‐19 observed in the cohorts. These alleles are found in greater frequencies in the North Western European population. This regional study provides evidence that HLA genotype influences clinical outcome in COVID‐19 infection. Validation studies must take account of the complex genetic architecture of the immune system across different geographies and ethnicities.

From hepatitis A to E: A critical review of viral hepatitis

Viral infections affecting the liver have had an important impact on humanity, as they have led to significant morbidity and mortality in patients with acute and chronic infections. Once an unknown etiology, the discovery of the viral agents triggered interest of the scientific community to establish the pathogenesis and diagnostic modalities to identify the affected population. With the rapid scientific and technological advances in the last centuries, controlling and even curing the infections became a possibility, with a large focus on preventive medicine through vaccination. Hence, a comprehensive understanding of hepatitis A, B, C, D and E is required by primary care physicians and gastroenterologists to provide care to these patients. The review article describes the epidemiology, pathogenesis, clinical presentation, diagnostic tools and current medication regimens, with a focus on upcoming treatment options and the role of liver transplantation.

Variation and expression of HLA-DPB1 gene in HBV infection

Hepatitis B virus (HBV) affects approximately 68 million people in China, and 10-15% of adults infected with HBV develop chronic hepatitis B, liver cirrhosis, liver failure or hepatocellular carcinoma (HCC). HLA-DPB1 gene polymorphism and expression have been shown to be associated with HBV infection susceptibility and spontaneous clearance. The aim of this study is to evaluate the role of HLA-DPB1 gene polymorphism in HBV infection. HLA-DPB1 and rs9277535 polymorphisms were investigated in 259 patients with HBV infection and 442 healthy controls (HCs) using sequence-based typing. The mRNA of HLA-DPB1 was measured by real-time polymerase chain reaction. HLA-DPB1 genes and rs9277535 polymorphisms were all associated with HBV infection in the Sichuan Han population. rs9277535A and HLA-DPB1*04:02 played a protective role against HBV infection. rs9277535G and DPB1*05:01 were associated with susceptibility to HBV infection. rs9277535GG had significantly higher HLA-DPB1 mRNA expression in the HBV infection group compared with the HC group. HLA-DPB1*05:01 and HLA-DPB1*21:01 had significantly lower mRNA expression in the HBV infection group compared with the HC group. The meta-analysis revealed that HLA-DPB1*02:01, HLA-DPB1*02:02, HAL-DPB1*04:01 and HLA-DPB1*04:02 protected against HBV infection, while HLA-DPB1*05:01, HLA-DPB1*09:01, and HLA-DPB1*13:01 were risk factors for susceptibility to HBV infection. HLA-DPB1*02:01, HLA-DPB1*02:02, and HLA-DPB1*04:01 were associated with HBV spontaneous clearance, while HLA-DPB1*05:01 was associated with chronic HBV infection. HLA-DPB1 alleles and rs9277535 have a major effect on the risk of HBV infection, and HBV infection is associated with lower HLA-DPB1 expression. HLA-DPB1 alleles have an important role in HBV susceptibility and spontaneous clearance.

In Silico Prediction of Human Leukocytes Antigen (HLA) Class II Binding Hepatitis B Virus (HBV) Peptides in Botswana

Hepatitis B virus (HBV) is the primary cause of liver-related malignancies worldwide, and there is no effective cure for chronic HBV infection (CHB) currently. Strong immunological responses induced by T cells are associated with HBV clearance during acute infection; however, the repertoire of epitopes (epi) presented by major histocompatibility complexes (MHCs) to elicit these responses in various African populations is not well understood. In silico approaches were used to map and investigate 15-mers HBV peptides restricted to 9 HLA class II alleles with high population coverage in Botswana. Sequences from 44 HBV genotype A and 48 genotype D surface genes (PreS/S) from Botswana were used. Of the 1819 epi bindings predicted, 20.2% were strong binders (SB), and none of the putative epi bind to all the 9 alleles suggesting that multi-epitope, genotype-based, population-based vaccines will be more effective against HBV infections as opposed to previously proposed broad potency epitope-vaccines which were assumed to work for all alleles. In total, there were 297 unique epi predicted from the 3 proteins and amongst, S regions had the highest number of epi (n = 186). Epitope-densities (Depi) between genotypes A and D were similar. A number of mutations that hindered HLA-peptide binding were observed. We also identified antigenic and genotype-specific peptides with characteristics that are well suited for the development of sensitive diagnostic kits. This study identified candidate peptides that can be used for developing multi-epitope vaccines and highly sensitive diagnostic kits against HBV infection in an African population. Our results suggest that viral variability may hinder HBV peptide-MHC binding, required to initiate a cascade of immunological responses against infection.

Hepatitis B infection outcome is associated with novel human leukocyte antigen variants in Ghanaian cohort

IMPACT STATEMENT

Genetic association studies can determine the effect size of gene loci on disease outcomes. In the arena of HBV infections, HLA alleles that associate with HBV outcomes can be used in clinical management decisions. This potential translational utility can shape the future management of HBV infections by identifying at-risk individuals and tailoring medical interventions accordingly. This precision medicine motif is currently only a nascent idea. However, it has stakes that may well override the current "wait and see" approach of clinical management of HBV infections. Here, we have identified HLA alleles associated with HBV outcome in a Ghanaian cohort. Our findings support the motif that HLA alleles associate with HBV outcome along geo-ethnic lines. This buttresses the need for further population pivoted studies. In the long term, our findings add to efforts towards the development of an HLA molecular-based algorithm for predicting HBV infection outcomes.

Diversity of HLA Class I and Class II blocks and conserved extended haplotypes in Lacandon Mayans

Here we studied HLA blocks and haplotypes in a group of 218 Lacandon Maya Native American using a high-resolution next generation sequencing (NGS) method. We assessed the genetic diversity of HLA class I and class II in this population, and determined the most probable ancestry of Lacandon Maya HLA class I and class II haplotypes. Importantly, this Native American group showed a high degree of both HLA homozygosity and linkage disequilibrium across the HLA region and also lower class II HLA allelic diversity than most previously reported populations (including other Native American groups). Distinctive alleles present in the Lacandon population include HLA-A*24:14 and HLA-B*40:08. Furthermore, in Lacandons we observed a high frequency of haplotypes containing the allele HLA-DRB1*04:11, a relatively frequent allele in comparison with other neighboring indigenous groups. The specific demographic history of the Lacandon population including inbreeding, as well as pathogen selection, may have elevated the frequencies of a small number of HLA class II alleles and DNA blocks. To assess the possible role of different selective pressures in determining Native American HLA diversity, we evaluated the relationship between genetic diversity at HLA-A, HLA-B and HLA-DRB1 and pathogen richness for a global dataset and for Native American populations alone. In keeping with previous studies of such relationships we included distance from Africa as a covariate. After correction for multiple comparisons we did not find any significant relationship between pathogen diversity and HLA genetic diversity (as measured by polymorphism information content) in either our global dataset or the Native American subset of the dataset. We found the expected negative relationship between genetic diversity and distance from Africa in the global dataset, but no relationship between HLA genetic diversity and distance from Africa when Native American populations were considered alone.

Immunity to Influenza is dependent on MHC II polymorphism: study with 2 HLA transgenic strains

Major histocompatibility complex II (MHC II) molecules are involved in antigen presentation and the development of a functional adaptive immune response. Evolutionary selection for MHC molecules that effectively clear infectious agents provides an advantage to humans. However, certain class II molecules are associated with autoimmune diseases. In this study we infected autoimmune-susceptible DRB1*0401.AEo and non-susceptible *0402.AEo mice with H1N1 influenza and determined clearance and protective immunity to H3N2 virus. *0401 mice generated a robust TLR-triggered immune response and cleared H1N1 influenza virus infection. After vaccination and challenge with H1N1, *0401 mice, when challenged with H3N2, generated cross-protective immunity to heterosubtypic H3N2 influenza strain whereas *0402 mice cleared the H1N1 infection but did not generate cross-protective immunity against the H3N2 influenza strain. The intracellular trafficking route of MHCII revealed that *0401 molecules traffic through the late endosome/lysosomes while *0402 molecules traffic into early endosomes. This suggested that trafficking of MHCII could affect the functional output of the innate immune response and clearance of viral infections. Also, DRB1*0401 mice live longer than HLA-DRB1*0402 mice. The study provides a potential hypothesis for evolutionary selection of *0401 molecule, even though it is associated with autoreactivity, which may be dependent on the availability of peptide repertoire of self-antigens.

The potential role for infections in the pathogenesis of autoimmune Addison's disease

Autoimmune Addison's disease (AAD), or primary adrenocortical insufficiency, is a classical organ-specific autoimmune disease with 160 years of history. AAD is remarkably homogeneous with one major dominant self-antigen, the cytochrome P450 21-hydroxylase enzyme, which is targeted by both autoantibodies and autoreactive T cells. Like most autoimmune diseases, AAD is thought to be caused by an unfortunate combination of genetic and environmental factors. While the number of genetic associations with AAD is increasing, almost nothing is known about environmental factors. A major environmental factor commonly proposed for autoimmune diseases, based partly on experimental and clinical data and partly on shared pathways between anti-viral immunity and autoimmunity, is viral infections. However, there are few reports associating viral infections to AAD, and it has proved difficult to establish which immunological processes that could link any viral infection with the initiation or progression of AAD. In this review, we will summarize the current knowledge on the underlying mechanisms of AAD and take a closer look on the potential involvement of viruses.

Host genetic factors affecting hepatitis B infection outcomes: Insights from genome-wide association studies

The clinical outcome of Hepatitis B Virus (HBV) infection depends on the success or failure of the immune responses to HBV, and varies widely among individuals, ranging from asymptomatic self-limited infection, inactive carrier state, chronic hepatitis, cirrhosis, hepatocellular carcinoma, to liver failure. Genome-wide association studies (GWAS) identified key genetic factors influencing the pathogenesis of HBV-related traits. In this review, we discuss GWAS for persistence of HBV infection, antibody response to hepatitis B vaccine, and HBV-related advanced liver diseases. HBV persistence is associated with multiple genes with diverse roles in immune mechanisms. The strongest associations are found within the classical human leukocyte antigen (HLA) genes, highlighting the central role of antigen presentation in the immune response to HBV. Associated variants affect both epitope binding specificities and expression levels of HLA molecules. Several other susceptibility genes regulate the magnitude of adaptive immune responses, determining immunity vs tolerance. HBV persistence and nonresponse to vaccine share the same risk variants, implying overlapping genetic bases. On the other hand, the risk variants for HBV-related advanced liver diseases are largely different, suggesting different host-virus dynamics in acute vs chronic HBV infections. The findings of these GWAS are likely to pave the way for developing more effective preventive and therapeutic interventions by personalizing the management of HBV infection.

Human leukocyte antigen A, B and Hepatitis B infection outcome: A meta-analysis

AIM

To evaluate the association between HLA A, B with chronic Hepatitis B by comprehensive meta-analysis.

METHODS

We searched PubMed and Cochrane databases, identified relevant studies, evaluated these for quality by New Castle Ottawa scale (NOS) and further analyzed the qualified data sets. Heterogeneity analyses were performed by Cochrane's Q test and I² tests. Pooled Odds ratio (OR) & 95% Confidence Interval (CI) were obtained by fixed effects, using Mantel-Haenszel's method for homogenous studies, and by using DerSimonian and Laird's method for heterogenous studies. Publication bias was determined by the Beggs test and Eggers test and all tests were two tailed to evaluate their significance.

RESULTS

The meta-analyses on 1652 healthy controls and 659 Chronic Hepatitis B (CHB) patients from 8 studies from various continents revealed a HLA B*07 (p value of Odds ratio (pOR)=0.004; OR Fixed effects=0.480 with 95%CI 0.290-0.794) and B*58 (pOR=0.029; OR Fixed Effects=0.020 with 95%CI 0.381-0.949) associated protection for CHB. The identified HLA B*35 associated risk (pOR 0.009; OR Fixed effect 1.445; 95% confidence interval 1.094-1.907) however did not stand the test of random effect model.

CONCLUSION

While HLA B*07 and B*58 are protective against CHB. The HLA B*35 associated marginal risk need to be further validated in well-designed global study on larger cohorts, considering the population, ethnic, epidemiological and HLA diversity at the sequence level: these may throw further light to utilize these markers in predictive medicine.

Homology modelling of frequent HLA class-II alleles: A perspective to improve prediction of HLA binding peptide and understand the HLA associated disease susceptibility

Human leukocyte antigen (HLA) plays significant role via the regulation of immune system and contribute in the progression and protection of many diseases. HLA molecules bind and present peptides to T- cell receptors which generate the immune response. HLA peptide interaction and molecular function of HLA molecule is the key to predict peptide binding and understanding its role in different diseases. The availability of accurate three dimensional (3D) structures is the initial step towards this direction. In the present work, homology modelling of important and frequent HLA-DRB1 alleles (07:01, 11:01 and 09:01) was done and acceptable models were generated. These modelled alleles were further refined and cross validated by using several methods including Ramachandran plot, Z-score, ERRAT analysis and root mean square deviation (RMSD) calculations. It is known that numbers of allelic variants are related to the susceptibility or protection of various infectious diseases. Difference in amino acid sequences and structures of alleles were also studied to understand the association of HLA with disease susceptibility and protection. Susceptible alleles showed more amino acid variations than protective alleles in three selected diseases caused by different pathogens. Amino acid variations at binding site were found to be more than other part of alleles. RMSD values were also higher at variable positions within binding site. Higher RMSD values indicate that mutations occurring at peptide binding site alter protein structure more than rest of the protein. Hence, these findings and modelled structures can be used to design HLA-DRB1 binding peptides to overcome low prediction accuracy of HLA class II binding peptides. Furthermore, it may help to understand the allele specific molecular mechanisms involved in susceptibility/resistance against pathogenic diseases.

Clinical Relevance of HLA Gene Variants in HBV Infection

Host gene variants may influence the natural history of hepatitis B virus (HBV) infection. The human leukocyte antigen (HLA) system, the major histocompatibility complex (MHC) in humans, is one of the most important host factors that are correlated with the clinical course of HBV infection. Genome-wide association studies (GWASs) have shown that single nucleotide polymorphisms (SNPs) near certain HLA gene loci are strongly associated with not only persistent HBV infection but also spontaneous HBV clearance and seroconversion, disease progression, and the development of liver cirrhosis and HBV-related hepatocellular carcinoma (HCC) in chronic hepatitis B (CHB). These variations also influence the efficacy of interferon (IFN) and nucleot(s)ide analogue (NA) treatment and response to HBV vaccines. Meanwhile, discrepant conclusions were reached with different patient cohorts. It is therefore essential to identify the associations of specific HLA allele variants with disease progression and viral clearance in chronic HBV infection among different ethnic populations. A better understanding of HLA polymorphism relevance in HBV infection outcome would enable us to elucidate the roles of HLA SNPs in the pathogenesis and clearance of HBV in different areas and ethnic groups, to improve strategies for the prevention and treatment of chronic HBV infection.

The HLA-DRB1 allele polymorphisms and nasopharyngeal carcinoma

Human leukocyte antigen (HLA)-DRB1 has been reported to influence individual's susceptibility to nasopharyngeal carcinoma (NPC) by many studies in recent years; however, these studies provided controversial results. The meta-analysis was thus conducted here to estimate the relationship between HLA-DRB1 polymorphisms and NPC. After an extensive review of journals from various databases (PubMed, the Web of Science, Embase, China National Knowledge Internet (CNKI), and Wanfang Database), 8 out of 69 case-control studies, including 778 cases and 1148 controls, were extracted. The results showed that 4 of 13 polymorphisms allele are statistically significantly associated with NPC, among them, HLA-DRB1*3, HLA-DRB1*9, and HLA-DRB1*10 may increase the risk of NPC while HLA-DRB1*01 has the opposite effect. The pooled odds ratio and 95 % confidence interval (CI) were 1.702 [95 % CI (1.047, 2.765)], 1.363 [95 % CI (1.029, 1.806)], 1.989 [95 % CI (1.042, 3.799)], and 0.461 [95 % CI (0.315, 0.676)], respectively. In a further ethnicity-based subgroup analysis, HLA-DRB1*08, HLA-DRB1*11, and HLA-DRB1*16 were found to be linked with NPC in Asian, Tunisian, and Caucasian, respectively. In Asian, HLA-DRB1*03, 08, and 10 may elevate the risk whereas HLA-DRB1*09 could lower it. In Tunisian, HLA-DRB1*01 and 11 are the protective factors while HLA-DRB1*03 is the only risk factor. In Caucasian, HLA-DRB1*01 and 03 increase the risk and HLA-DRB1*16 lowers it. The most frequent statistically associated gene is found to be HLA-DRB1*03 which has protective influence on Asian and Tunisian. In conclusion, HLA-DRB1*01, DRB1*03, DRB1*09, and DRB1*10 are related with NPC susceptibility, and the association of HLA-DRB1*08, DRB1*11, and DRB1*16 with NPC risk are significantly different in different ethnicities.

MHC class II super-enhancer increases surface expression of HLA-DR and HLA-DQ and affects cytokine production in autoimmune vitiligo

Genetic risk for autoimmunity in HLA genes is most often attributed to structural specificity resulting in presentation of self-antigens. Autoimmune vitiligo is strongly associated with the MHC class II region. Here, we fine-map vitiligo MHC class II genetic risk to three SNPs only 47 bp apart, located within a predicted super-enhancer in an intergenic region between HLA-DRB1 and HLA-DQA1, localized by a genome-wide association study of 2,853 Caucasian vitiligo patients. The super-enhancer corresponds to an expression quantitative trait locus for expression of HLA-DR and HLA-DQ RNA; we observed elevated surface expression of HLA-DR (P = 0.008) and HLA-DQ (P = 0.02) on monocytes from healthy subjects homozygous for the high-risk SNP haplotype. Unexpectedly, pathogen-stimulated peripheral blood mononuclear cells from subjects homozygous for the high-risk super-enhancer haplotype exhibited greater increase in production of IFN-γ and IL-1β than cells from subjects homozygous for the low-risk haplotype. Specifically, production of IFN-γ on stimulation of dectin-1, mannose, and Toll-like receptors with Candida albicans and Staphylococcus epidermidis was 2.5- and 2.9-fold higher in high-risk subjects than in low-risk subjects, respectively (P = 0.007 and P = 0.01). Similarly, production of IL-1β was fivefold higher in high-risk subjects than in low-risk subjects (P = 0.02). Increased production of immunostimulatory cytokines in subjects carrying the high-risk haplotype may act as an "adjuvant" during the presentation of autoantigens, tying together genetic variation in the MHC with the development of autoimmunity. This study demonstrates that for risk of autoimmune vitiligo, expression level of HLA class II molecules is as or more important than antigen specificity.

Host genetic variants influencing the clinical course of hepatitis B virus infection

The clinical course of hepatitis B virus (HBV) infection greatly differs in individuals. Various viral, host, and environmental factors influence the natural history of HBV infection. Recent genome-wide association studies identified several host genetic factors influencing the clinical course of HBV infection. Genetic variations in HLA class II loci were significantly associated with susceptibility to persistent HBV infection. Other polymorphisms in or near the genes EHMT2, TCF19, and HLA-C, located near HLA class II loci, and UBE2L3 were also associated with persistent HBV infection. Meanwhile, polymorphisms in KIF1B, GRIK1, and STAT4 were associated with HBV-related hepatocellular carcinoma (HCC). Interestingly, HLA class II genetic variations were strongly associated with not only persistent HBV infection, but also disease progression and HBV-related HCC in chronic hepatitis B. Understanding the various genetic factors associated with the clinical course of HBV infection is essential for personalized treatment and surveillance of disease progression and HCC.

Immune-Regulatory Events in the Clearance of HBsAg in Chronic Hepatitis B: Focuses on HLA-DP

Successful clearance of hepatitis B virus (HBV) is a promising event in which host's immune system will attempt to get rid of the virus. The immunological events of HBsAg seroclearance have attracted great attention in both natural history investigations and therapeutic trials. Recent genome-wide association studies (GWAS) has confirmed polymorphisms in the human leukocyte antigen (HLA)-DP locus associated with spontaneous HBV clearance. In this review the impact of host immune response in declining HBsAg during the natural history of the infection has been discussed.

Cytokines pre-determined by genetic factors are involved in pathogenesis of Rheumatoid arthritis

Rheumatoid arthritis (RA) is associated with the presence of autoreactive CD4 T cells that produce pro-inflammatory cytokines. The role of genetic factors in the predilection to develop RA is strongly supported by the increased presence of certain HLA class II molecules in patients. The HLA class II genes are highly polymorphic and are critical for generating an immune response to clear infections. Production of Th1 and Th17 response by the CD4 T cells helps to clear infections. HLA-DQ8 is a promiscuous binder and presents many peptides generating immune response and producing a Th17 response. DRB1∗0401 is associated with the production of both IL-17 and IFN-γ. Thus both DR4 and DQ8 can clear infections by producing TH1/Th17 cytokines, but their presence increases the risk of developing RA. Using transgenic mice expressing human HLA genes, we have shown that HLA polymorphism determines the cytokine profile. DRB1∗04 molecules modulate the DQ8-restricted response and determine the outcome of arthritis in mice carrying DR4/DQ8 haplotype. Thus, interaction between DQ and DR molecules determines the cytokine milieu and propensity of the HLA haplotype to predispose to autoimmunity.

Xeroderma pigmentosum group D polymorphisms and esophageal cancer susceptibility: A meta-analysis based on case-control studies

AIM: To clarify the effects of the xeroderma pigmentosum group D (XPD) Asp312Asn and Lys751Gln gene polymorphisms on the risk of esophageal cancer (EC).

METHODS: A computerised literature search was conducted to identify the relevant studies from the PUBMED and EMBASE databases, reviews, and reference lists of relevant articles. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the associations between the XPD Asp312Asn and/or Lys751Gln polymorphisms and EC susceptibility. Statistical analyses were performed using the software Stata 12.0. A fixed or random effects model was selected based on a heterogeneity test. Publication bias was estimated using funnel plots and Egger’s linear regression method. Subgroup analyses were performed based on histological type and ethnicity.

RESULTS: Thirteen case-control studies with a total of 10 comparisons for the Asp312Asn polymorphism, including 2373 cases and 3175 controls, and 15 comparisons for the Lys751Gln polymorphism, including 3226 cases and 5237 controls, were recruited for the meta-analysis. In terms of the XPD Asp312Asn polymorphism, significantly increased EC risks were identified in the Asp/Asn vs Asp/Asp comparison (OR = 1.17, 95%CI: 1.02-1.33, P = 0.03) and in the dominant-model comparison (Asn/Asn+Asp/Asn vs Asp/Asp: OR = 1.18, 95%CI: 1.04-1.34, P = 0.01). However, no significant associations were found in the Asn/Asn vs Asp/Asp comparison (OR = 1.30, 95%CI: 1.00-1.70, P = 0.05) or in the recessive-model comparison (Asn/Asn vs Asp/Asn + Asp/Asp: OR = 1.17, 95%CI: 0.91-1.50, P = 0.22). In terms of the XPD Lys751Gln polymorphism, a significant association with EC susceptibility was found under the recessive model (Gln/Gln vs Lys/Gln+Lys/Lys: OR = 1.21, 95%CI: 1.02-1.43, P = 0.03). However, no associations were identified in the other comparisons (co-dominant model: Lys/Gln vs Lys/Lys: OR = 1.11, 95%CI: 0.94-1.31, P = 0.20; Gln/Gln vs Lys/Lys: OR = 1.31, 95%CI: 0.98-1.75, P = 0.07; dominant model: OR = 1.14, 95%CI: 0.96-1.35, P = 0.14).

CONCLUSION: The results of this meta-analysis suggest that the XPD Asp312Asn and Lys751Gln gene polymorphisms are associated with a significantly increased risk for EC.

Association of human leukocyte antigen DQB1 and DRB1 alleles with chronic hepatitis B

AIM: To investigate the effect of human leukocyte antigen (HLA) DRB1 and DQB1 alleles on the inactive and advanced stages of chronic hepatitis B.

METHODS: Patient records at a single institution’s hepatology clinic were reviewed. Demographic data, laboratory results, endoscopy results, virological parameters, biopsy scores and treatment statuses were recorded. In total, 355 patients were eligible for the study, of whom 226 (63.7%) were male. Overall, 82 (23.1%) were hepatitis B early antigen (HBeAg) positive, 87 (24.5%) had cirrhosis, and 66 (18.6%) had inactive disease. The presence of DQB1 and DRB1 alleles was determined by polymerase chain reaction with sequence-specific primers. The distribution of the genotyped alleles among patients with cirrhosis and patients with chronic active hepatitis was analyzed.

RESULTS: The most frequent HLA DQB1 allele was DQB1*03:01 (48.2%), and the most frequent HLA DRB1 allele was DRB1*13/14 (51.8%). DQB1*05:01 was more frequent in patients with active disease than in inactive patients (27% vs 9.1%; P = 0.002, P_c = 0.026). DRB1*07 was rare in patients with cirrhosis compared with non-cirrhotics (3.4% vs 16%; P = 0.002, P_c = 0.022). Older age (P < 0.001) and male gender (P = 0.008) were the other factors that affected the presence of cirrhosis. In a multivariate logistic regression analysis, DRB1*07 remained a significant negative predictor of cirrhosis (P = 0.015). A bioinformatics analysis revealed that a polymorphic amino acid sequence in DRB1*07 may alter interaction with the T-cell recognition site.

CONCLUSION: This study demonstrates that HLA alleles may influence cirrhosis development and disease activity in Turkish chronic hepatitis B patients.

Use of serum levels of proinflammatory cytokine IL-1alpha in chronic hepatitis B

Background:

The reasons for the chronic viral persistence of hepatitis B virus infection (HBV) are unknown, but are probably related to host immune factors. Cytokines play a significant role in immune defense. Interleukin-1 (IL-1) is a proinflammatory cytokine and some studies have demonstrated that IL-1 production was impaired in patients with chronic infections of hepatitis B virus, implying that IL-1 may play a role in viral clearance, progression of fibrosis and in malignant potential of HBV. In this study, along with routine laboratory tests, has been performed the analysis of serum levels of proinflammatory cytokine IL-1 α in order of better understanding and monitoring of chronic hepatitis B.

Objective:

The aim of this study was to analyze the usefulness of laboratory tests, which are routinely used in the assessment of liver disease with specified immunological parameters in patients with chronic hepatitis B.

Patients and methods:

Total of 60 subjects was divided into two groups: HBV- PCR positive and negative group. The control group of 30 healthy participants was included. Apart from standard laboratory tests, the analysis included serum levels of cytokine IL-1 α.

Results and discussion:

IL-1α had the highest mean concentration in group 1–viral hepatitis C, with PCR positive test (5.73 pg / ml), and then in group 2- viral hepatitis B, PCR negative test (5.39 pg / ml). ANOVA test proves that IL-1α in the healthy group (3) was different from other groups as follows: in relation to group 1 statistical significance level was p <0.001 (F = 32 75 5); in relation to group 2 was also statistically significant at p <0.001 (F = 182 361); Cytokine IL-1 was statistically analyzed separately and compared by group 1 and 2 using Student t-test for independent samples. Statistical significance was observed at p = 0.026. IL-1 α was positively correlated with the duration of the illness (p <0.01) and with serum ALT activity (p <0.01) and serum AST activity (p <0.01). Using multivariate analysis model “Factor Analysis”, was made significant stratification predictive parameters in relation to the cytokine IL-1α, stratified significance is indicated as follows: 1. Age, 2. history of receiving transfusions, 3. ALT, 4. AST, 5. MELD score (negative), 6. Child-Pugh score (Negative).

Conclusion:

IL-1α was significantly elevated in inflammatory conditions of pronounced activity (PCR positive hepatitis). IL-1α may have important role as marker of both inflammation and hepatic injury, particularly in the course of hepatitis B. Results suggest that inflammatory and immune parameters, analyzed together can significantly contribute to the understanding and predicting of chronic liver damage. IL-1 can be used as important parameter of inflammatory activity and fibrosis evaluation and eventually prediction of malignant transformation in chronic liver damage.

Virus-related liver cirrhosis: molecular basis and therapeutic options

Chronic infections with hepatitis B virus (HBV) and/or hepatitis C virus (HCV) are the major causes of cirrhosis globally. It takes 10-20 years to progress from viral hepatitis to cirrhosis. Intermediately active hepatic inflammation caused by the infections contributes to the inflammation-necrosis-regeneration process, ultimately cirrhosis. CD8(+) T cells and NK cells cause liver damage via targeting the infected hepatocytes directly and releasing pro-inflammatory cytokine/chemokines. Hepatic stellate cells play an active role in fibrogenesis via secreting fibrosis-related factors. Under the inflammatory microenvironment, the viruses experience mutation-selection-adaptation to evade immune clearance. However, immune selection of some HBV mutations in the evolution towards cirrhosis seems different from that towards hepatocellular carcinoma. As viral replication is an important driving force of cirrhosis pathogenesis, antiviral treatment with nucleos(t)ide analogs is generally effective in halting the progression of cirrhosis, improving liver function and reducing the morbidity of decompensated cirrhosis caused by chronic HBV infection. Interferon-α plus ribavirin and/or the direct acting antivirals such as Vaniprevir are effective for compensated cirrhosis caused by chronic HCV infection. The standard of care for the treatment of HCV-related cirrhosis with interferon-α plus ribavirin should consider the genotypes of IL-28B. Understanding the mechanism of fibrogenesis and hepatocyte regeneration will facilitate the development of novel therapies for decompensated cirrhosis.

Long-term outcomes after nucleos(t)ide analogue discontinuation in HBeAg-positive chronic hepatitis B patients

Nucleos(t)ide analogue (NUC) resistance is an important clinical risk resulting from long-term therapy in chronic hepatitis B (CHB) management. Discontinuation of NUCs is a feasible strategy to reduce resistance. We aimed to observe the outcomes after NUC withdrawal in HBeAg-positive CHB patients. A total of 97 patients (11 patients with HBsAg loss and 86 patients with sustained HBeAg seroconversion) were enrolled. HBV DNA levels and alanine aminotransferase (ALT) levels were monitored regularly after discontinuation. Relapse was defined as HBV DNA levels >2000 IU/mL in at least two determinations more than 4 weeks apart. HBeAg seroconversion was achieved within 48 weeks (interquartile range (IQR), 24-72 weeks). The time on consolidation therapy was 96 weeks (IQR, 84-144 weeks). No relapses occurred for HBsAg loss patients. Evidence of relapse was observed in 9.3% of HBeAg seroconversion patients. All relapse cases occurred within 48 weeks after discontinuation. The time to relapse was 33 ± 15 weeks. Elevation of HBV DNA and ALT levels over baseline were only observed in 12.5% of relapse patients. There were no significant differences in baseline characteristics (sex, HBV genotype, age or ALT levels) or time on consolidation therapy between patients with relapse or sustained response. NUC discontinuation in HBeAg-positive CHB patients is feasible after achieving HBeAg seroconversion at a minimum of 24 weeks. There is further benefit to prolonging the time on consolidation therapy to reduce relapse. More than 48 weeks of sustained response is a predictive marker for long-term sustained response.

HLA class II associated with outcomes of hepatitis B and C infections

Several factors influence the clinical course of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection. The human leukocyte antigen (HLA) system, the major histocompatibility complex (MHC) in humans, has been considered one of the most important host factors with respect to outcomes. To date, conventional genotyping studies have shown that HLA class II loci are mainly associated with spontaneous clearance of HBV and HCV. However, the specific HLA locus associated with the outcomes of hepatitis virus infection remains unclear. A recent genome-wide association study (GWAS) using a comprehensive approach for human genotyping demonstrated single nucleotide polymorphisms (SNPs) associated with the outcomes of hepatitis virus infection. Examination of large numbers of cohorts revealed that several SNPs in both HLA-DPA1 and HLA-DPB1 loci are associated with persistent HBV infection in Asian populations. To date, however, few studies have focused on HLA-DP because polymorphisms of HLA-DP haplotype do not vary greatly as compared with other loci of HLA. There are not enough studies to reveal the function of HLA-DP. GWAS additionally detected candidate SNPs within HLA loci associated with chronic HBV or HCV hepatitis, hepatic fibrosis, and the development of hepatocellular carcinoma. The results of one cohort were not always consistent with those of other cohorts. To solve several controversial issues, it is necessary to validate reported SNPs on HLA loci in global populations and to elucidate the HLA-allele-regulated molecular response to hepatitis virus infection.

HLA class II molecules influence susceptibility versus protection in inflammatory diseases by determining the cytokine profile

The MHC in humans encodes the most polymorphic genes, the HLA genes, which are critical for the immune system to clear infection. This can be attributed to strong selection pressure as populations moved to different parts of the world and encountered new kinds of infections, leading to new HLA class II alleles. HLA genes also have the highest relative risk for autoimmune diseases. Three haplotypes, that is, HLA-DR2DQ6, DR4DQ8, and DR3DQ2, account for HLA association with most autoimmune diseases. We hypothesize that these haplotypes, along with their multiple subtypes, have survived bottlenecks of infectious episodes in human history because of their ability to present pathogenic peptides to activate T cells that secrete cytokines to clear infections. Unfortunately, they also present self-peptides/mimics to activate autoreactive T cells secreting proinflammatory cytokines that cause autoimmune diseases.

Role of single nucleotide polymorphisms of KIF1B gene in HBV-associated viral hepatitis

BACKGROUND/AIM

Kinesin family member 1B (KIF1B) gene resides in the chromosomal region 1p36.22 and has been reported to have frequent deletions in a variety of human cancers. A recent genome wide association study (GWAS) study conducted on a Chinese population has reported the involvement of a KIF1B genetic variant in Hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). This study aims to investigate the significance of KIF1B genetic variations in HBV-associated hepatitis in patients of Saudi Arabian ethnicity.

METHODS

TaqMan genotyping assay was used to investigate the association of three SNPs (rs17401966, rs12734551, and rs3748578) in 584 normal healthy controls and 660 HBV-infected patients. The patients were categorized into inactive carriers (Case I), active carriers (Case II), Cirrhosis (Case III) and Cirrhosis-HCC (Case IV) sub-groups.

RESULTS

Since SNPs rs12734551 and rs3748578 are in strong linkage disequilibrium (LD) with rs17401966, only results for the latter SNP are reported. Therefore, the allele frequency of rs17401966 among HBV-infected patients and healthy controls were comparable and therefore, no significant association was observed (P=0.2811, Odds Ratio (OR) 0.897). A similar analysis was performed among the different sub-groups in order to determine whether KIF1B SNPs were associated with the advancement of the disease. No significant differences were observed in any of the comparisons performed.

CONCLUSION

Polymorphisms at KIF1B gene locus investigated in this study showed no significant association with HBV infection or with HBV-associated diseases such as liver cirrhosis or HCC.