Association of selective HLA class II susceptibility-conferring and protective haplotypes with type 2 diabetes in patients from Bahrain and Lebanon

Investigating associations between HLA DQA1 ~ DQB1 haplotypes, H. pylori infection, metaplasia, and anti-CagA IgA seropositivity in a Turkish gastritis cohort

Helicobacter pylori was reported as an important cause of gastritis, and gastric ulcers and CagA oncoprotein-producing H. pylori subgroups were blamed to increase the severity of gastritis. Disparities were reported in that the presence of serum anti-CagA IgA was not parallel with CagA-positive H. pylori cohabitation. We hypothesized that the HLA-DQA1 ~ DQB1 haplotypes in human populations include protective haplotypes that more effectively present immunogenic CagA peptides and susceptible haplotypes with an impaired capacity to present CagA peptides. We recruited patients (n = 201) admitted for gastroendoscopy procedures and performed high-resolution HLA-DQA1 and DQB1 typing. Serum anti-CagA IgA levels were analyzed by ELISA (23.0% positive), and H. pylori was classified as positive or negative in gastric mucosal tissue slides (72.6% positive). The HLA DQA1*05:05 allele (29.1%) and HLA DQB1*03:01 allele (32.8%) were found at the highest frequency among gastritis patients of Turkish descent. In HLA DQA1*05:05 ~ DQB1*03:01 double homozygous (7.3%) and heterozygous (40.7%) haplotype carriers, the presence of anti-CagA IgA decreased dramatically, the presence of H. pylori increased, and the presence of metaplasia followed a decreasing trend. The DQ protein encoded by HLA DQA1*05:05-DQ*03:01 showed a low binding affinity to the CagA peptide when binding capacity was analyzed by the NetMHCIIPan 4.0 prediction method. In conclusion, HLA DQA1 ~ DQB1 polymorphisms are crucial as host defense mechanisms against CagA H. pylori since antigen binding capacity plays a crucial role in anti-CagA IgA production.

HLA-DRB1 genes and the expression dynamics of HLA CIITA determine the susceptibility to T2DM

Type 2 diabetes mellitus (T2DM) is a disease with polygenic inheritance. The expression of major histocompatibility complex class II genes are regulated by several trans-activators. We have studied the expression of HLA-DRB1, RFX, CIITA-P1, PIV transactivators, immunophenotyping of cells, SNPs in CIITA-168 (A/G) and IFN-γ + 874 (T/A) in T2DM patients and controls (n = 201 each). We observed increased frequencies of DRB1*03, DRB1*04 and DRB1*07 and decreased frequencies of DRB1*10, DRB1*14, and DRB1*15 alleles among patients. Significant up-regulations of HLA-DRB1 genes were observed in patients (p < 0.0001). Down-regulated expressions were documented in DRB1*03-homo (p < 0.002) and DRB1*04-homo (p < 0.009) patients. No significant differences were observed for CIITA-P1 expression except DRB1*04-pooled (p < 0.0113). The CIITA-PIV was up-regulated in overall (p < 0.0001), DRB1*03-pooled (p < 0.0006), DRB1*03-hetero (p < 0.0006) and DRB1*03-homo (p < 0.001) T2DM patients. However, significant down-regulations were documented for DRB1*04-pooled (p < 0.040), DRB1*04-hetero (p < 0.060), and DRB1*04-homo (p < 0.027) combinations. Further, significant down-regulations of RFX5 were observed in overall (p < 0.0006), DRB1*04-pooled (p < 0.0022), and DRB1*04-hetero (p < 0.0004) combinations. Immunophenotyping studies revealed significant increase of CD45⁺ CD14^-, CD19⁺, CD14^- and CD8 cells and elevated level of expression of IFN-γ (p < 0.0001) in patients. A significant increase of TT (p < 3.35 × 10^-6) and decrease of TA (p < 4.57 × 10^-4) genotypes of IFN-γ + 874 (T/A) and an increase of GG (p < 0.001) and decrease of AG (p < 8.24 × 10^-5) genotypes of CIITA-168 A/G SNPs were observed. The combinatorial analysis revealed susceptible associations for DRB1*03 + AA, *03 + AG, *03 + GG and *04 + GG and protective associations for DRB1*10 + AG, *10 + GG, *15 + AG, and *14 + GG combinations. Thus, the present study corroborated the effect of differential expressions of promoters of risk alleles in the pathogenesis of T2DM.

HLA-DRB1* and DQB1* allele and haplotype diversity in eight tribal populations: Global affinities and genetic basis of diseases in South India

The distribution of HLA class-II DRB1* and DQB1* alleles/ haplotypes were studied in 438 individuals of 8 Dravidian tribal groups inhabiting the Western Ghats, south India. The HLA typing was performed by PCR-SSP method. In order to identify the 5-locus Ancestral Extended Haplotypes (AEH), the alleles of HLA-A, -B and -C loci were typed for DNAs with predominant 2-locus haplotypes. The analyses have revealed allele HLA-DRB1*15 as the most predominant allele (Lowest / Highest range: Urali, 14.81 / Malasar, 48.94), followed by the alleles DRB1*10 (Katunayakan, 1.85 / Paliyan, 48.21), DRB1*14 (Paliyan 4.46 / Katunayakan, 40.74), DRB1*12 (Mannan, 1.64 / Katunayakan, 20.37) and DRB1*03 (Mannan, 1.64 / Urali, 29.63). The most frequent DQB1* alleles were DQB1*02 (Paliyan 3.57 / Urali, 23.15), DQB1*05 (Katunayakan, 27.77 / Paliyan 84.82) and DQB1*06 (Malasar, 8.51 / Kuruman, 33.51). The most predominant two-locus haplotypes observed were DRB1*15-DQB1*05, DRB1*10-DQB1*05, DRB1*15-DQB1*06 and DRB1*04-DQB1*05. The present study of HLA immunogenetics of south Indian tribes have revealed the presence of globally shared two and 5-locus haplotypes. Many of these haplotypes were implicated in a number of diseases in south India. We observed the presence of ancestral extended haplotypes (AEHs), hitherto not reported in Indian populations such as, A*68-B*35-C*02-DRB1*15:01-DQB1*05:01, A*24-B*57-C*06-DRB1*04:01-DQB1*05:01 and A*24-B*35-C*02-DRB1*15:01-DQB1*05:02. The dendrogram based phylogenetic analyses have revealed the Caucasian affinity of Urali, palaeo-Mediterranean and Indo-European affinity of Malasar tribes. The presence of globally shared susceptible and protective haplotypes reiterated the mosaic immunogenetic fabric of south Indian tribes.

HLA class II alleles and risk for peripheral neuropathy in type 2 diabetes patients

The potential impact of human leukocyte antigen (HLA) genotype variations on development of diabetic peripheral neuropathy (DPN) is not well determined. This study aimed to identify the association of HLA class II alleles with DPN in type 2 diabetes (T2D) patients. Totally 106 T2D patients, 49 with DPN and 57 without DPN, and 100 ethnic-matched healthy controls were analyzed. Both groups of the patients were matched based on sex, age, body mass index (BMI) and duration of T2D. Polyneuropathy was diagnosed using electrodiagnostic methods. HLA-DRB1 and DQB1 genotyping was performed in all subjects by the polymerase chain reaction with sequence-specific primers (PCR-SSP) method. T2D patients with DPN showed higher frequencies of HLA-DRB1*10 and DRB1*12 alleles compared to control group (P = 0.04). HLA-DQB1*02 allele and HLA-DRB1*07-DQB1*02 haplotype were associated with a decreased risk for developing DPN in T2D patients (P = 0.02 and P = 0.05 respectively). Also, patients with severe neuropathy showed higher frequencies of DRB1*07 (P = 0.003) and DQB1*02 (P = 0.02) alleles than those with mild-to-moderate form of neuropathy. The distribution of DRB1 and DQB1 alleles and haplotypes were not statistically different between all patients and healthy controls. Our findings implicate a possible protective role of HLA-DQB1*02 allele and HLA-DRB1*07-DQB1*02 haplotype against development of peripheral neuropathy in T2D patients. Therefore, variations in HLA genotypes might be used as genetic markers for prediction and potentially management of neuropathy in T2D patients.

Distribution of HLA DRB1 and DQB1 alleles and DRB1-DQB1 haplotypes among Bahraini women with polycystic ovary syndrome

OBJECTIVE

This study investigated the association between HLA-DRB1 and -DQB1 alleles and DRB1-DQB1 haplotypes, and polycystic ovary syndrome (PCOS) in Bahraini women.

DESIGN

Case-control, retrospective study.

METHODS

Study subjects comprised 80 women with PCOS, and 169 age- and ethnically-matched control women. DRB1 and DQB1 genotyping was done by PCR-SSP.

RESULTS

Of the 13 DRB1 alleles and 5 DQB1 alleles identified, DRB1*10 (14.3% vs. 4.4%) and DRB1*14 (8.7% vs. 1.1%), along with DQB1*05 (35.0% vs. 23.9%), were the most frequent alleles in cases, while DRB1*11 (15.3% vs. 6.8%) was the frequent allele found in controls. The association of PCOS with DRB1*10 (Pc<0.001), DRB1*14 (Pc<0.001), DQB1*05 (Pc=0.040), but not DRB1*11 (Pc=0.076) persisted after correcting for multiple comparisons. DRB1-DQB1 haplotype analysis identified nine common shared haplotypes in women with PCOS and control women, with a frequency exceeding 1%. Significantly higher frequency of DRB1*10-DQB1*05 (12.4% vs. 3.1%) and DRB1*14-DQB1*03 (5.6% vs. 1.0%), and reduced frequency of DRB1*11-DQB1*03 (4.1% vs. 14.1%) haplotypes were seen in women with PCOS vs. control women, thus assigning PCOS-susceptible and -protective nature to these haplotypes, respectively. This association persisted after controlling for multiple comparisons.

CONCLUSION

Our results confirm an association of HLA-DRB1 and -DQB1 alleles and haplotypes with PCOS susceptibility in Bahraini Arabs, further underscoring the immunological/inflammatory nature of this disorder.

Association of vitamin D and vitamin D receptor gene polymorphisms with chronic inflammation, insulin resistance and metabolic syndrome components in type 2 diabetic Egyptian patients

Background

To date the published data concerning the possible interplay between vitamin D (VitD) and Vit D receptor (VDR) gene polymorphism with the immune/inflammatory mediators in type 2 diabetes mellitus (DM) is insufficient. Some of the immune non-classical actions of vitamin D may point to its role in the pathogenesis of type 2 DM through down-regulation of cytokines (IL-6). Although there is evidence to support a relationship among vitamin D status, chronic inflammation and insulin resistance, the underlying mechanism requires further exploration. We aimed to investigate the role of vitamin D in chronic inflammation and insulin resistance in type 2 DM. Moreover, to examine the association of VDR gene polymorphisms [VDR 2228570 C > T (FokI); VDR 1544410 A > G (BsmI)] with the components of metabolic syndrome (MetSyn) in type 2 diabetic Egyptian patients .

Subjects and methods

A total of 190 subjects were enrolled in this study, 60 controls and 130 type 2 diabetic patients (Group II). Group II was subdivided into 63 patients without MetSyn (subgroup IIa) and 67 patients with MetSyn (subgroup IIb). Genetic analysis for VDR gene polymorphisms was done in all subjects. VitD and IL-6 plasma levels were estimated.

Results

The TT genotype for the VDR FokI was significantly more frequent in subgroup IIb than in subgroup IIa and controls (X² = 6.83, P = 0.03 and X² = 16.592, P = 0.000) respectively. The T allele was more frequent in the MetSyn group as compared to diabetics without MetSyn (p = 0.001), odds ratio (OR) and 95% CI for the T allele of C > T (FokI) = 2.30 (1.37–3.86). We did not detect any significant difference in VDR BsmI genotypes between patients and control groups (P = 0.947). FokI VDR was significantly associated with the lipid profile parameters, VitD and IL-6 plasma levels in subgroup IIa and associated with HOMA-IR, insulin, VitD, IL-6 levels, waist circumference (WC) and body mass index (BMI) in subgroup IIb while BsmI VDR variant was associated only with VitD values in both subgroups.

Conclusion

The present study suggests an interaction between VDR polymorphisms and important components of MetSyn, VitD and pro-inflammatory cytokines (IL-6). FokI VDR polymorphisms may be linked to mild inflammation and insulin resistance and might represent a genetic determinant for developing MetSyn in type 2 diabetic Egyptian patients. The challenge is determining the mechanisms of VitD action for recommendation of VitD supplementation that reduces the risks of MetSyn, insulin resistance and progression to type 2 diabetes.