HLA polymorphisms are associated with Helicobacter pylori infected gastric cancer in a high risk population, China

Association of HLA gene polymorphisms with Helicobacter pylori related gastric cancer-a systematic review

The appropriate host cell immune responses for the progression of several diseases, including gastric or stomach cancer (GC), are significantly influenced by HLA polymorphisms. Our objective was to systematically review the evidence linking HLA polymorphisms with the risk of Helicobacter. pylori related GC. We conducted a comprehensive literature search to identify studies published between 2000 and April 2023 on the association of HLA polymorphisms with H. pylori related GC using databases such as Medline through PubMed, Embase, Web of Science (core collection), The Cochrane Library, and Scopus. Two authors independently screened articles, extracted data, and assessed the risk of bias using the Risk of Bias Assessment tool for Non-randomized Studies. From 7872 retrieved studies, 19 met inclusion criteria, encompassing 1656 cases and 16,787 controls across four World Health Organization regions, with Japan contributing the most studies. We explored HLA-A/B/C, HLA-DRB1/DQA1/DQB1, HLA-G, and MICA alleles. Of 29 significant HLA polymorphisms identified, 18 showed a positive association with GC, whereas 11 were negatively associated. HLA-DQB1*06 allele was most frequently associated to susceptibility, as reported in four studies, followed by HLA-DRB1*04 and HLA-DQA1*01, each reported in two studies. Conversely, HLA-G*01, HLA-DQA1*01, HLA-DQA1*05, and HLA-DQB1*03 were identified as protective in two studies each. Additionally, five genotypes and six haplotypes were reported as positive, whereas three genotypes and two haplotypes were negative factors for the disease incidence or mortality. Despite heterogeneity in the study population and types of HLA polymorphisms examined, our analysis indicates certain polymorphisms are associated with H. pylori related GC progression and mortality in specific populations.

Host Transcriptional Regulatory Genes and Microbiome Networks Crosstalk through Immune Receptors Establishing Normal and Tumor Multiomics Metafirm of the Oral-Gut-Lung Axis

The microbiome has shown a correlation with the diet and lifestyle of each population in health and disease, the ability to communicate at the cellular level with the host through innate and adaptative immune receptors, and therefore an important role in modulating inflammatory process related to the establishment and progression of cancer. The oral cavity is one of the most important interaction windows between the human body and the environment, allowing the entry of an important number of microorganisms and their passage across the gastrointestinal tract and lungs. In this review, the contribution of the microbiome network to the establishment of systemic diseases like cancer is analyzed through their synergistic interactions and bidirectional crosstalk in the oral-gut-lung axis as well as its communication with the host cells. Moreover, the impact of the characteristic microbiota of each population in the formation of the multiomics molecular metafirm of the oral-gut-lung axis is also analyzed through state-of-the-art sequencing techniques, which allow a global study of the molecular processes involved of the flow of the microbiota environmental signals through cancer-related cells and its relationship with the establishment of the transcription factor network responsible for the control of regulatory processes involved with tumorigenesis.

Cysteine carboxyethylation generates neoantigens to induce HLA-restricted autoimmunity

Autoimmune diseases such as ankylosing spondylitis (AS) can be driven by emerging neoantigens that disrupt immune tolerance. Here, we developed a workflow to profile posttranslational modifications involved in neoantigen formation. Using mass spectrometry, we identified a panel of cysteine residues differentially modified by carboxyethylation that required 3-hydroxypropionic acid to generate neoantigens in patients with AS. The lysosomal degradation of integrin αIIb [ITGA2B (CD41)] carboxyethylated at Cys96 (ITGA2B-ceC96) generated carboxyethylated peptides that were presented by HLA-DRB1*04 to stimulate CD4⁺ T cell responses and induce autoantibody production. Immunization of HLA-DR4 transgenic mice with the ITGA2B-ceC96 peptide promoted colitis and vertebral bone erosion. Thus, metabolite-induced cysteine carboxyethylation can give rise to pathogenic neoantigens that lead to autoreactive CD4⁺ T cell responses and autoantibody production in autoimmune diseases.

Genetic Analyses of Common Infections in the Avon Longitudinal Study of Parents and Children Cohort

The burden of infections on an individual and public health is profound. Many observational studies have shown a link between infections and the pathogenesis of disease; however a greater understanding of the role of host genetics is essential. Children from the longitudinal birth cohort, the Avon Longitudinal Study of Parents and Children, had 14 antibodies measured in plasma at age 7: Alpha-casein protein, beta-casein protein, cytomegalovirus, Epstein-Barr virus, feline herpes virus, Helicobacter pylori, herpes simplex virus 1, influenza virus subtype H1N1, influenza virus subtype H3N2, measles virus, Saccharomyces cerevisiae, Theiler's virus, Toxoplasma gondii, and SAG1 protein domain, a surface antigen of Toxoplasma gondii measured for greater precision. We performed genome-wide association analyses of antibody levels against these 14 infections (N = 357 - 5010) and identified three genome-wide signals (P < 5×10^-8), two associated with measles virus antibodies and one with Toxoplasma gondii antibodies. In an association analysis focused on the human leukocyte antigen (HLA) region of the genome, we further detected 15 HLA alleles at a two-digit resolution and 23 HLA alleles at a four-digit resolution associated with five antibodies, with eight HLA alleles associated with Epstein-Barr virus antibodies showing strong evidence of replication in UK Biobank. We discuss how our findings from antibody levels complement other studies using self-reported phenotypes in understanding the architecture of host genetics related to infections.

Association between human leukocyte antigen gene polymorphisms and multiple EPIYA-C repeats in gastrointestinal disorders

BACKGROUND

Polymorphisms of human leukocyte antigen (HLA) genes are suggested to increase the risk of gastric cancer (GC).

AIM

To investigate the HLA allele frequencies of patients with GC relative to a control group in terms of CagA+ multiple (≥ 2) EPIYA-C repeats.

METHODS

The patient group comprised 94 patients [44 GC and 50 duodenal ulcer (DU) patients], and the control group comprised 86 individuals [(50 non-ulcer dyspepsia patients and 36 people with asymptomatic Helicobacter pylori (H. pylori)]. Polymerase chain reaction was performed for the amplification of the H. pylori cagA gene and typing of EPIYA motifs. HLA sequence-specific oligonucleotide (SSO) typing was performed using Lifecodes SSO typing kits (HLA-A, HLA-B HLA-C, HLA-DRB1, and HLA-DQA1-B1 kits).

RESULTS

The comparison of GC cases in terms of CagA+ multiple (≥ 2) EPIYA-C repeats showed that only the HLA-DQB1*06 allele [odds ratio (OR): 0.37, P = 0.036] was significantly lower, but significance was lost after correction (Pc = 0.1845). The HLA-DQA1*01 allele had a high ratio in GC cases with multiple EPIYA-C repeats, but this was not significant in the univariate analysis. We compared allele frequencies in the DU cases alone and in GC and DU cases together using the same criterion, and none of the HLA alleles were significantly associated with GC or DU. Also, none of the alleles were detected as independent risk factors after the multivariate analysis. On the other hand, in a multivariate logistic regression with no discriminative criterion, HLA-DQA1*01 (OR = 1.848), HLA-DQB1*06 (OR = 1.821) and HLA-A*02 (OR = 1.579) alleles were detected as independent risk factors for GC and DU.

CONCLUSION

None of the HLA alleles were detected as independent risk factors in terms of CagA+ multiple EPIYA-C repeats. However, HLA-DQA1*01, HLA-DQB1*0601, and HLA-A*2 were independent risk factors with no criterion in the multivariate analysis. We suggest that the association of these alleles with gastric malignancies is not specifically related to cagA and multiple EPIYA C repeats.

The immunogenetic diversity of the HLA system in Mexico correlates with underlying population genetic structure

We studied HLA class I (HLA-A, -B) and class II (HLA-DRB1, -DQB1) allele groups and alleles by PCR-SSP based typing in a total of 15,318 mixed ancestry Mexicans from all the states of the country divided into 78 sample sets, providing information regarding allelic and haplotypic frequencies and their linkage disequilibrium, as well as admixture estimates and genetic substructure. We identified the presence of 4268 unique HLA extended haplotypes across Mexico and find that the ten most frequent (HF > 1%) HLA haplotypes with significant linkage disequilibrium (Δ'≥0.1) in Mexico (accounting for 20% of the haplotypic diversity of the country) are of primarily Native American ancestry (A*02~B*39~DRB1*04~DQB1*03:02, A*02~B*35~DRB1*08~DQB1*04, A*68~B*39~DRB1*04~DQB1*03:02, A*02~B*35~DRB1*04~DQB1*03:02, A*24~B*39~DRB1*14~DQB1*03:01, A*24~B*35~DRB1*04~DQB1*03:02, A*24~B*39~DRB1*04~DQB1*03:02, A*02~B*40:02~DRB1*04~DQB1*03:02, A*68~B*35~DRB1*04~DQB1*03:02, A*02~B*15:01~DRB1*04~DQB1*03:02). Admixture estimates obtained by a maximum likelihood method using HLA-A/-B/-DRB1 as genetic estimators revealed that the main genetic components in Mexico as a whole are Native American (ranging from 37.8% in the northern part of the country to 81.5% in the southeastern region) and European (ranging from 11.5% in the southeast to 62.6% in northern Mexico). African admixture ranged from 0.0 to 12.7% not following any specific pattern. We were able to detect three major immunogenetic clusters correlating with genetic diversity and differential admixture within Mexico: North, Central and Southeast, which is in accordance with previous reports using genome-wide data. Our findings provide insights into the population immunogenetic substructure of the whole country and add to the knowledge of mixed ancestry Latin American population genetics, important for disease association studies, detection of demographic signatures on population variation and improved allocation of public health resources.

Association between polymorphisms in HLA-A, HLA-B, HLA-DR, and DQ genes from gastric cancer and duodenal ulcer patients and cagL among cagA-positive Helicobacter pylori strains: The first study in a Turkish population

Colonization of the human gastric mucosa by H. pylori may cause peptic and duodenal ulcers (DUs), gastric lymphomas, and gastric cancers. The cagL gene is a component of cag T4SS and is involved in cagA translocation into host. An association between the risk of gastric cancer and the type of HLA class II (DR and/or DQ) was suggested in different populations. The aim of this study was to investigate, the clinical association of the cagL gene with host HLA alleles in H. pylori strains that were isolated from patients with gastric cancer, DU, and non-ulcer dyspepsia (NUD) and to determine the HLA allele that confers susceptibility or resistance for the risk of gastric cancer and DU development in Turkish patients. A total of 94 patients (44 gastric cancer and 50 DU patients; 58 male, 36 female; mean age, 49.6 years), and 86 individuals (50 NUD patients and 36 persons with normal gastrointestinal system [NGIS]; 30 male, 56 female; mean age, 47.3 years) were included as the patient and the control groups, respectively. CagA and cagL were determined by PCR method. DNA from peripheral blood samples was obtained by EZ-DNA extraction kit. For HLA SSO typing, LIFECODES SSO Typing kits (HLA-A, HLA-B HLA-C, HLA-DRB1 and HLA-DQA1/B1 kits) were used. The CagL/CagA positivity distribution in the groups were as follows: 42 (95.4%) gastric cancer, 46 (92%) DU and, 34 (68%) NUD and no NGIS cases. The HLA-DQA1*01 (OR: 3.82) allele was significantly different, suggesting that these individuals with H. pylori strains harbouring the CagL/CagA positivity are susceptible to the risk of gastric cancer and DU, and the HLA-DQA1*05 (OR, 0.318) allele was suggested as a protective allele for the risk of gastric cancer and DU using univariate analyses. HLA-DQA1*01 (OR, 2.21), HLA-DQB1*06 (OR, 2.67), sex (male, OR, 2.27), and CagL/CagA/(<2) EPIYA C repeats (OR, 5.72) were detected independent risk factors that increased the risk of gastric cancer and DU using multivariate analyses. However, the HLA-DRB1*04 (OR, 0.28) allele was shown to be a protective allele, which decreased the risk of gastric cancer and DU. Gastric pathologies result from an interaction between bacterial virulence factors, host epigenetic and environmental factors, and H. pylori strain heterogeneity, such as genotypic variation among strains and variations in H. pylori populations within an individual host.

HLA-DQB1*03 genotype and perioperative blood transfusion are not conducive to the prognosis of patients with gastric cancer

BACKGROUND

Gastric cancer (GC) is a disease associated with a higher incidence and mortality, and some host genetic polymorphisms have been reported as potential factors contributing to the development of GC. In view of this, the study was conducted to investigate the effects of HLA-DQB1 gene polymorphisms and perioperative blood transfusion on prognosis of patients with gastric cancer (GC).

METHODS

A total of 142 patients with GC (case group) and 150 healthy controls (control group) were enrolled. Relationship between HLA-DQB1 gene polymorphisms, perioperative blood transfusion, and clinical pathological parameters of patients with GC after operation was analyzed. Kaplan-Meier curve was applied for analyzing survival rate of patients with GC, and Cox multivariate regression analysis for prognostic factors of patients with GC.

RESULTS

The frequency of HLA-DQB1*03 gene was increased in patients with GC. Patients with GC with HLA-DQB1*03 genotype had higher number of tumor size >6 cm, deeper depth of infiltration, higher LNM rate, and later stage of disease. Patients with HLA-DQB1*03 genotype had lower survival rate compared with other genotypes. Anemia before operation, depth of infiltration in T3 stage and T4 stage, LNM in N1 stage and N2 stage, and HLA-DQB1*03 genotype were regarded as independent risk factors for patients with GC.

CONCLUSION

These results demonstrate that HLA-DQB1*03 genotype and perioperative blood transfusion are not conducive to the prognosis of patients with GC, which could provide a reference for the treatment of GC.

EVALUATION OF HUMAN LEUKOCYTE ANTIGEN CLASS I AND II ANTIGENS IN HELICOBACTER PYLORI-POSITIVE PEDIATRIC PATIENTS WITH ACTIVE GASTRITIS AND DUODENAL ULCER

BACKGROUND

As being the first bacteria determined to be carcinogenic, Helicobacter pylori (H. pylori) is a pathogen localized in the stomach in more than half of the world population. Some earlier studies have found a relation between tissue histocompatibility antigens and gastric cancers depending on the regions.

OBJECTIVE

The present study aimed to determine the distribution of human leukocyte antigen (HLA) class I and class II antigens in H. pylori-positive pediatric patients with active gastritis and duodenal ulcer, excluding cancer cases, in our center.

METHODS

The study included 40 patients diagnosed with H. pylori-positive active gastritis and duodenal ulcer and 100 controls consisting of healthy donor candidates. The HLA class I and class II antigens were studied in the isolated DNA samples using the polymerase chain reaction sequence-specific oligonucleotide probes.

RESULTS

The frequency of HLA-B*51 antigen was significantly higher in the patient group than in the control group (40% vs 17%; P=0.003). There was no difference between the two groups in terms of the frequencies of HLA-A, HLA-C, HLA-DR, and HLA-DQ antigens.

CONCLUSION

It was determined that HLA-B*51 plays a critical role in H. pylori infection.

Human leukocyte antigen class I alleles and haplotypes associated with primary hepatocellular carcinoma in persistent HBV-infected patients

Many studies have shown that Human leukocyte antigen (HLA) class I alleles are associated with the development of various cancers. However, its role in hepatocellular carcinoma (HCC) is still unknown. To investigate whether HLA class I allelic polymorphism is related to the development of hepatitis B virus(HBV)-associated HCC, a total of 326 HBV-infected patients (138 individuals with HCC and 188 well-matched controls without HCC) were enrolled in this study. HLA-A, -B, and -C were genotyped by polymerase chain reaction-sequencing based typing (PCR-SBT) method. We identified HLA-B(∗)35:01:01G as a risk factor for HBV-related HCC development independent of our previous findings in HLA region (OR, 12.04; p, 0.0028; pc, 0.04). HLA-A(∗)11:01:01G, B(∗)58:01:01G, C(∗)03:02:01G and some of their extended haplotypes were found as potential susceptible factors for HCC development. HLA-B(∗)46:01:01G and some of its extended haplotypes were found as potential protective factors for HCC development. Our results support that specific HLA class I alleles and haplotypes may affect the risk of HBV-related HCC development. The findings may help to determine better approaches for prevention and treatment of HCC in these patients.

Why are East Asians more susceptible to several infection-associated cancers (carcinomas of the nasopharynx, stomach, liver, adenocarcinoma of the lung, nasal NK/T-cell lymphomas)?

There are at least five cancers with uniquely high incidence amongst East and Southeast Asian ethnic groups - namely nasopharyngeal carcinoma (NPC); gastric carcinoma; hepatocellular carcinoma (HCC); adeno-carcinoma of the lung in female non-smokers and nasal NK/T-cell lymphomas. They all appear to be related to an infective cause (Epstein Barr Virus, Helicobacter pylori, hepatitis B virus). We hypothesize that a genetic bottleneck 30,000years ago at the Last Glacial Maximum could have resulted in unique genetic polymorphisms in Toll-like receptor 8, making East Asians more vulnerable to these infective associated cancers. This bottleneck could have been caused by the presence of malaria in the southern Himalayan conduit between central and East Asia; and only those with an attenuated innate immune response to the malarial parasite (perhaps reflected by the TLR8 polymorphism) were spared the ravages of cerebral malaria; allowing these people to cross into east Asia, but then rendering them susceptible to later endemic infections and their associated cancers.

Synergistic effect of HLA class II loci and cytokine gene polymorphisms on the risk of gastric cancer in Japanese patients with Helicobacter pylori infection

It has been reported that polymorphisms of human leukocyte antigen (HLA) genes and several cytokine genes are associated with an increased risk of developing gastric cancer (GC). However, the results of studies from different geographic regions, ethnic groups and study groups are inconsistent. The aim of this study was to evaluate the influence of H. pylori infection and host genetic factors on GC susceptibility in Japanese patients with GC. We analyzed genotypes for HLA class I and II, tumor necrosis factor alpha, interleukin (IL)-1beta, IL-1 receptor, IL-4, IL-4Ralpha and IL-10 in 330 H. pylori-infected noncardia patients with GC and 190 H. pylori-infected nonulcer dyspeptic controls. Haplotype analyses indicated that the frequencies of the HLA DRB1*0405 and DQB1*0401 alleles were increased in the patients with intestinal-type GC when compared with controls (both DRB1*0405 and DQB1*0401: p = 0.015, OR = 1.57, 95% CI = 1.09-2.26), but the changes were not statistically significant after correction for multiple comparisons. None of the cytokine gene polymorphisms were associated with GC susceptibility, whether patients with GC were analyzed as a group according to the histological subtype. Of interest was the comparison of controls and patients with intestinal-type GC. The frequency of an IL-10-592AA homozygote showing concomitant carriage of the HLA DRB1*0405-DQB1*0401 haplotype was significantly higher in patients with intestinal-type GC (chi(2) = 6.369, p = 0.0116, p(c) = 0.0464, OR = 2.43, 95% CI = 1.21-4.48). Our results suggest that the HLA class II and IL-10-592A/C polymorphisms synergistically affect the susceptibility to GC development of H. pylori-infected individuals in the Japanese population.

Impact of pepsinogen C polymorphism on individual susceptibility to gastric cancer and its precancerous conditions in a Northeast Chinese population

PURPOSE

Human pepsinogen C (PGC) is an aspartic protease produced specifically by the gastric mucosa, and is considered as a mature marker of gastric epithelium. This study examined the contributions of PGC polymorphisms and the Helicobacter pylori (H. pylori) infection to the risk of gastric cancer (GC), and its precancerous conditions in a Northeast Chinese population.

METHODS

The PGC insertion/deletion polymorphism was evaluated by polymerase chain reaction analysis, followed by direct DNA sequencing in 564 cases of GC, atrophic gastritis (AG), gastric ulcer (GU) and superficial gastritis (as control). All cases were frequency-matched 1:1 by gender and age (+/-5). H. pylori infection was identified by serum anti-H. pylori IgG measurement through enzyme-linked immunosorbent assay.

RESULTS

Patients with a homozygous PGC allele 1 genotype had a significant risk of AG [adjusted odds ratio (OR) 3.11; 95% confidence interval (CI) 1.44-6.71] or of GC (OR 3.00; 95% CI 1.38-6.51), and a significantly elevated risk of intestinal metaplasia (OR 1.90, 95% CI 1.11-3.27). PGC polymorphism with H. pylori infection increased risk of GU (OR 8.69; 95% CI 1.01-74.69), and AG (OR 11.12; 95% CI 1.37-90.84) or GC (OR 10.61; 95% CI 1.28-87.79) in a super-multiplicative manner. The S value was 5.40, 6.48 and 4.34; and the AP value was 72.09, 7.00 and 69.69%, respectively.

CONCLUSIONS

The PGC gene polymorphism increases an individual's susceptibility to GC and its precancerous conditions. Moreover, the PGC gene polymorphism shows a positive link to H. pylori infection in the development of GC.

HLA-A2 expression, stage, and survival in colorectal cancer

INTRODUCTION

Most cancer vaccination trials have been performed in human leukocyte antigen (HLA)-A2 positive populations. Some studies have used HLA-A2 negative patients as control group. However, HLA-type and HLA-expression can interact with tumor biology and possibly affect prognosis. HLA-A2 negative patients might constitute an inadequate control group.

MATERIALS AND METHODS

Patients with colorectal cancer were serologically analyzed for HLA-A2 expression. Patients were evaluated for tumor stage, grading, tumor location. Overall survival (OAS) of HLA-A2 positive and HLA-A2 negative patients was compared.

RESULTS

One hundred forty-four patients were evaluable (50% HLA-A2+). Median age was 62 years. UICC stage III or IV: 45.8%. Gender, location, and UICC stage were equally distributed between HLA-A2 subgroups. HLA-A2 positive patients more frequently had grade 3 histology (27.8% vs 13.9%) and chemotherapy (62.9% vs 45.6%). At a median follow-up of 75.8 months, median OAS for the entire study population was 123.3 months, 5-year OAS was 77.5%. No statistically significant difference in OAS was observed between HLA-A2 positive and negative patients (116.5 vs 157 months, 5-year-OAS 74.1+/-11.6% vs 81+/-11.6%, p=0.46). Expectedly, patients with UICC stage I and II disease lived significantly longer than patients with stage III and IV (5-year OAS 94.3% vs 53.4%; p<0.001). A significantly superior OAS was also found for women, independent of stage or HLA status.

CONCLUSION

HLA-A2 positive patients exhibit poorer tumor differentiation. This might account for a non-significant difference in OAS. The use of HLA-A2 negative patients as control cohort in CRC vaccinations would rather underestimate potential treatment-related survival effects. Therefore, we suggest they constitute a valid auxiliary control group.

Association of polymorphisms of human leucocyte antigen-DQA1 and DQB1 alleles with chronic hepatitis B virus infection, liver cirrhosis and hepatocellular carcinoma in Chinese

To investigate whether human leucocyte antigen (HLA) class II DQA1 and DQB1 gene polymorphisms are associated with chronic hepatitis B virus (HBV) infection and development of HBV-related liver cirrhosis (LC) and hepatocellular carcinoma (HCC), we detected the DQA1 and DQB1 allele polymorphisms in 168 HBV carriers (including 48 chronic hepatitis B, 42 LC and 78 HCC patients) and 100 controls who had recovered from HBV infection by using polymerase chain reaction amplification with sequence-specific primers (PCR-SSP). Our data suggest that DQA1*0102 and DQA1*0104 were associated with protection from chronic HBV infection (P(c) = 0.003) and development of LC (P(c) = 0.001), respectively, whereas DQB1*0201 conferred susceptible effect on chronic HBV infection (P(c) = 0.008). We also found that DQA1*0601, DQB1*0601 and DQA1*0201 showed some susceptible effect on chronic HBV infection and LC, respectively, however, these associations were no longer significant after Bonferroni correction (P(c) = 0.390, P(c) = 0.475 and P(c) = 0.140, respectively). No significant association has been found between DQA1 and DQB1 alleles and development of HCC. These results indicate that different subtypes of HLA-DQA1 and DQB1 are associated with development of chronic HBV infection and LC, respectively, in Han Chinese population.

Association of DRB1 shared epitope genotypes with early mortality in rheumatoid arthritis: results of eighteen years of followup from the early rheumatoid arthritis study

OBJECTIVE

To determine whether the HLA-DRB1 shared epitope (SE) is associated with early mortality and specific causes of death in rheumatoid arthritis (RA).

METHODS

HLA-DRB1 genotyping was carried out on blood samples from 767 patients recruited for the Early RA Study (ERAS), a multicenter, inception cohort study with followup over 18 years. Dates and causes of death (n = 186) were obtained from the Office of National Statistics. The association of HLA-DRB1 alleles with risk of mortality was assessed using Cox proportional hazards regression analyses. Multivariate stepwise models were used to assess the predictive value of HLA-DRB1 genotypes compared with other potential baseline risk factors.

RESULTS

The SE was not significantly associated with overall mortality. However, the presence of 2 SE alleles was associated with risk of mortality from ischemic heart disease (hazard ratio [HR] 2.02 [95% confidence interval 1.04-3.94], P = 0.04), and malignancy (HR 2.18 [95% confidence interval 1.17-4.08], P = 0.01). Analysis of specific SE genotypes (corrected for age and sex) revealed that the HLA-DRB1*0101/*0401 and 0404/*0404 genotypes were the strongest predictors of mortality from ischemic heart disease (HR 5.11 and HR 7.55, respectively), and DRB1*0101/*0401 showed a possible interaction with smoking. Male sex, erythrocyte sedimentation rate, and Carstairs Deprivation Index were also predictive, but the Health Assessment Questionnaire score, rheumatoid factor, nodules, and swollen joint counts were not. Mortality due to malignancy was particularly associated with DRB1*0101 genotypes.

CONCLUSION

The risk of mortality due to ischemic heart disease or cancer in RA is increased in patients carrying HLA-DRB1 genotypes with particular homozygous and compound heterozygous SE combinations.

Role of the HLA-DQ locus in the development of chronic gastritis and gastric carcinoma in Mexican patients

AIM: To determine the HLA-DQ locus in Mexican patients with Chronic gastritis and gastric adenocarcinoma.

METHODS: Oligotyping for HLA-DQ locus was performed in 45 Mexican patients with chronic gastritis and 13 Mexican patients with diffuse-type gastric adenocarcinoma, and was then compared with 99 clinically healthy unrelated individuals. H pylori infection and CagA status were assessed in patients by enzyme-linked immunosorbent assay (ELISA) method.

RESULTS: We found a significant increased frequency of HLA-DQB1*0401 allele in H pylori-positive patients with chronic gastritis when compared with healthy subjects [19 vs 0%, P = 1 × 10^-7, odds ratio (OR) = 4.96; 95% confidence interval (95% CI), 3.87-6.35]. We also found a significant increased frequency of HLA-DQB1*0501 in patients with diffuse-type gastric carcinoma in comparison with healthy individuals (P = 1 × 10^-6, OR = 13.07; 95% CI, 2.82-85.14).

CONCLUSION: HLA-DQ locus may play a different role in the development of H pylori-related chronic gastritis and diffuse-type gastric adenocarcinoma in the Mexican Mestizo population.

Association of the -183 polymorphism in the IFN-gamma gene promoter with hepatitis B virus infection in the Chinese population

Interferon-gamma (IFN-gamma) is a pleiotropic cytokine that plays an important role in regulating cellular immune responses. Regulation of IFN-gamma expression is considered to be strictly controlled at the transcriptional level. Two single-nucleotide polymorphisms (SNPs) within the human IFN-gamma promoter (at positions -183 and -155) are considered to influence the promoter activity by altering the acting transcription factor-1 (AP-1) binding. We sought to assess the association between the SNPs of the IFN-gamma promoter and the host susceptibility to hepatitis B virus (HBV) infection, as well as its interaction with age and gender. No polymorphism at position-155 was detected in any of the participants, but a significant difference was found in the polymorphism at position -183 between the cases and controls (G/T and T/T vs. GG; P < 0.01, odds ratio (OR) = 4.50 (95% confidence interval (CI) = 2.23-9.09). A susceptibility analysis revealed a gradually increased trend of the OR value from the young to the old group (OR = 3.03, 4.17, and 5.56). Similarly, the association of the -183 polymorphism was markedly different in females (OR = 5.71). Our data suggest that the polymorphism at position -183 of the IFN-gamma gene promoter may be associated with susceptibility to HBV infection, and age and gender factors are coordinative risk factors.

The importance of immune gene variability (MHC) in evolutionary ecology and conservation

Genetic studies have typically inferred the effects of human impact by documenting patterns of genetic differentiation and levels of genetic diversity among potentially isolated populations using selective neutral markers such as mitochondrial control region sequences, microsatellites or single nucleotide polymorphism (SNPs). However, evolutionary relevant and adaptive processes within and between populations can only be reflected by coding genes. In vertebrates, growing evidence suggests that genetic diversity is particularly important at the level of the major histocompatibility complex (MHC). MHC variants influence many important biological traits, including immune recognition, susceptibility to infectious and autoimmune diseases, individual odours, mating preferences, kin recognition, cooperation and pregnancy outcome. These diverse functions and characteristics place genes of the MHC among the best candidates for studies of mechanisms and significance of molecular adaptation in vertebrates. MHC variability is believed to be maintained by pathogen-driven selection, mediated either through heterozygote advantage or frequency-dependent selection. Up to now, most of our knowledge has derived from studies in humans or from model organisms under experimental, laboratory conditions. Empirical support for selective mechanisms in free-ranging animal populations in their natural environment is rare. In this review, I first introduce general information about the structure and function of MHC genes, as well as current hypotheses and concepts concerning the role of selection in the maintenance of MHC polymorphism. The evolutionary forces acting on the genetic diversity in coding and non-coding markers are compared. Then, I summarise empirical support for the functional importance of MHC variability in parasite resistance with emphasis on the evidence derived from free-ranging animal populations investigated in their natural habitat. Finally, I discuss the importance of adaptive genetic variability with respect to human impact and conservation, and implications for future studies.