HLA Class I in Egyptian patients with Behçet’s disease: new association with susceptibility, protection, presentation and severity of manifestations

The complex HLA-E-nonapeptide in Behçet disease

Introduction

The knowledge of the aetiology of Behçet disease (BD), an immune-mediated vasculitis, is limited. HLA-B, mainly HLA-B51, and HLA-A molecules are associated with disease, but the ultimate cause of this association remains obscure. There is evidence that NK cells participate in the etiopathology of BD. NK cells have activator and inhibitor surface receptors, like the KIR and the NKG2 families. Classical HLA-class I molecules (A, B and C) are keys in the activity control of the NK because they are KIR ligands. Most NKG2 receptors bind HLA-E, which presents only nonapeptides derived from the signal peptide of other class-I molecules.

Objective

This study investigates the contribution of the pair HLA-E and ligand, nonapeptide derived from the 3-11 sequence of the signal peptides of class I classical molecules, to the susceptibility to BD.

Methods

We analyzed the frequency of the HLA-derivated nonapeptide forms in 466 BD patients and 444 controls and an HLA-E functional dimorphism in a subgroup of patients and controls. Results: In B51 negative patients, the frequency of VMAPRTLLL was lower (70.4% versus 80.0% in controls; P=0.006, Pc=0.04, OR=0.60, 95%CI 0.41-0.86), and the frequency of VMAPRTLVL was higher (81.6% versus 71.4% in controls; P=0.004, Pc=0.03, OR=1.78, 95%CI 1.20-2.63). In homozygosity, VMAPRTLLL is protective, and VMAPRTLVL confers risk. The heterozygous condition is neutral. There were no significant differences in the distribution of the HLA-E dimorphism.

Discussion

Our results explain the association of BD with diverse HLA-A molecules, reinforce the hypothesis of the involvement of the NK cells in the disease and do not suggest a significant contribution of the HLA-E polymorphism to disease susceptibility.

SARS-CoV-2 Proteome Harbors Peptides Which Are Able to Trigger Autoimmunity Responses: Implications for Infection, Vaccination, and Population Coverage

Autoimmune diseases (ADs) could occur due to infectious diseases and vaccination programs. Since millions of people are expected to be infected with SARS-CoV-2 and vaccinated against it, autoimmune consequences seem inevitable. Therefore, we have investigated the whole proteome of the SARS-CoV-2 for its ability to trigger ADs. In this regard, the entire proteome of the SARS-CoV-2 was chopped into more than 48000 peptides. The produced peptides were searched against the entire human proteome to find shared peptides with similar experimentally confirmed T-cell and B-cell epitopes. The obtained peptides were checked for their ability to bind to HLA molecules. The possible population coverage was calculated for the most potent peptides. The obtained results indicated that the SARS-CoV-2 and human proteomes share 23 peptides originated from ORF1ab polyprotein, nonstructural protein NS7a, Surface glycoprotein, and Envelope protein of SARS-CoV-2. Among these peptides, 21 peptides had experimentally confirmed equivalent epitopes. Amongst, only nine peptides were predicted to bind to HLAs with known global allele frequency data, and three peptides were able to bind to experimentally confirmed HLAs of equivalent epitopes. Given the HLAs which have already been reported to be associated with ADs, the ESGLKTIL, RYPANSIV, NVAITRAK, and RRARSVAS were determined to be the most harmful peptides of the SARS-CoV-2 proteome. It would be expected that the COVID-19 pandemic and the vaccination against this pathogen could significantly increase the ADs incidences, especially in populations harboring HLA-B*08:01, HLA-A*024:02, HLA-A*11:01 and HLA-B*27:05. The Southeast Asia, East Asia, and Oceania are at higher risk of AD development.

Behçet disease, new insights in disease associations and manifestations: a next-generation sequencing study

Behçet disease is a multi-system disease associated with human leukocyte antigen (HLA) class I polymorphism. High-resolution next-generation sequencing (NGS) with haplotype analysis has not been performed previously for this disease. Sixty Egyptian patients diagnosed according to the International Study Group (ISG) criteria for Behçet disease and 160 healthy geographic and ethnic-matched controls were genotyped for HLA class I loci (HLA-A, B, C). For HLA class II loci (DRB1, DRB3/4/5, DQA1, DQB1, DPA1, DPB1), 40 control samples were genotyped. High-resolution HLA genotyping was performed using NGS and the results were analyzed. Clinical manifestations were oral ulcers (100%), genital ulcers (100%), eye (55%) and neurological (28%) and vascular involvement (35%). HLA-B*51:08 [odds ratio (OR) = 19·75, 95% confidence interval (CI) = 6·5-79; P < 0·0001], HLA-B*15:03 (OR = 12·15, 95% CI = 3·7-50·7; P < 0·0001), HLA-C*16:02 (OR = 6·53, 95% CI = 3-14; P < 0·0001), HLA-A*68:02 (OR = 3·14, 95% CI = 1·1-8·9; P < 0·01) were found to be associated with Behçet disease, as were HLA-DRB1*13:01 and HLA-DQB1*06:03 (OR = 3·39, 95% CI = 0·9-18·9; P = 0·04 for both). By contrast, HLA-A*03:01 (OR = 0·13, 95% CI = 0-0·8; P = 0·01) and HLA-DPB1*17:01 were found to be protective (OR = 0·27, 95% CI = 0·06-1·03; P = 0·02). We identified strong linkage disequilibrium between HLA-B*51:08 and C*16:02 and A*02:01 in a haplotype associated with Behçet disease. HLA-B*51:08 was significantly associated with legal blindness (OR = 2·98, 95% CI = 1·06-8·3; P = 0·01). In Egyptian Behçet patients, HLA-B*51:08 is the most common susceptibility allele and holds poor prognosis for eye involvement.

A comprehensive overview on the genetics of Behçet's disease

Behçet's disease (BD) is a systemic and inflammatory disease, characterized mainly by recurrent oral and genital ulcers, eye involvement, and skin lesions. Although the exact etiopathogenesis of BD remains unrevealed, a bulk of studies have implicated the genetic contributing factors as critical players in disease predisposition. In countries along the Silk Road, human leukocyte antigen (HLA)-B51 has been reported as the strongest genetically associated factor for BD. Genome-wide association studies, local genetic polymorphism studies, and meta-analysis of combined data from Turkish, Iranian, and Japanese populations have also identified new genetic associations with BD. Among these, other HLA alleles such as HLA-B*15, HLA-B*27, HLA-B*57, and HLA-A*26 have been found as independent risk factors for BD, whereas HLA-B*49 and HLA-A*03 are independent protective alleles for BD. Moreover, other genes have also reached the genome-wide significance level of association with BD susceptibility, including IL10, IL23R-IL12RB2, IL12A, CCR1-CCR3, STAT4, TNFAIP3, ERAP1, KLRC4, and FUT2. Also, several rare nonsynonymous variants in TLR4, IL23R, NOD2, and MEFV genes have been reported to be involved in BD pathogenesis. According to genetic determinants in the loci outside the MHC region that are contributed to the host defense, immunity, and inflammation pathways, it is suggested that immune responses to the pathogen as an important environmental factor and mucosal immunity contribute to BD susceptibility.

Contribution of HLA-B*51:01 and -A*26:01 to Behçet's disease and their clinical association in Thai patients

AIMS

To investigate susceptible human leukocyte antigen (HLA) alleles and their associations with clinical features in Thai patients with Behçet's disease (BD).

METHOD

Eighteen HLA-A and 36 HLA-B alleles were determined in 42 Thai BD patients and 99 healthy controls (HCs) by reverse line blot assay, and reconfirmed by MICRO SSP assay.

RESULTS

The BD patients had significantly higher allele frequency (AF) of HLA-B*51 than the HCs (13.10% vs 5.05%, P = .025). The AF of HLA-A*26, -A*26:01 and -B*51:01 also was higher and almost reached statistical significance (5.59% vs 1.52%, P = .054, 5.95% vs 1.52%, P = .054 and 10.71% vs 4.04%, P = .051, respectively). However, the BD patients had significantly higher AF of either HLA-A*26:01 or -B*51:01 (16.67% vs 5.56%, P = .005), or -A*26:01 or -B*51X (19.05% vs 6.56%, P = .003). The AF of HLA-B*51:01 and -B*51X increased significantly in -A*26:01 non-carrier BD patients (12.16% vs 4.17%, P = .024 and 14.86% vs 5.21%, P = .019, respectively); and that of HLA-A*26:01 was significantly higher in -B*51X non-carrier BD patients (7.58% vs 1.67%, P = .034). HLA-B*51:01 associated significantly with the presence of posterior uveitis and visual impairment (18.18% vs 2.50%, P = .031 for both conditions). HLA-B*51:01 was not observed in BD patients with gastrointestinal involvement or arthritis. Furthermore, the AF of HLA-B*51:01 was significantly higher in HLA-A*26:01 non-carrier BD patients without arthritis (17.30% vs 0%, P = .050).

CONCLUSION

HLA-B*51:01 was a susceptible allele for Thai BD patients, and associated with posterior uveitis and visual impairment. HLA-A*26:01 was another susceptible allele in HLA-B*51X non-carrier patients. The protective effect of HLA-B*51:01 on arthritis needs further investigation.

Past and Present Behçet's Disease Animal Models

Behçet's disease (BD) is presumably an autoinflammatory disease of unknown etiology for which several animal models have been described over the years. Agents and methods used for the development of these models have ranged from the herpes simplex type one virus (hsv-1) pathogen to the use of transgenic mice. Other models have also been used to investigate a possible autoimmune component. Each model possesses its own unique set of benefits and shortcomings, with no one model fully being able to recapitulate the disease phenotype. Here, we review the proposed models and provide commentary on their effectiveness and usefulness in studying the disease.

Indonesians Human Leukocyte Antigen (HLA) Distributions and Correlations with Global Diseases

In Human, Major Histocompatibility Complex known as Human Leukocyte Antigen (HLA). The HLA grouped into three subclasses regions: the class I region, the class II region, and the class III region. There are thousands of polymorphic HLAs, many of them are proven to have correlations with diseases. Indonesia consists of diverse ethnicity people and populations. It carries a unique genetic diversity between one and another geographical positions. This paper aims to extract Indonesians HLA allele data, mapping the data, and correlating them with global diseases. From the study, it is found that global diseases, like Crohn's disease, rheumatoid arthritis, Graves' disease, gelatin allergy, T1D, HIV, systemic lupus erythematosus, juvenile chronic arthritis, and Mycobacterial disease (tuberculosis and leprosy) suspected associated with the Indonesian HLA profiles.

The association analysis between HLA-A*26 and Behçet's disease

The strongest genetic risk factor of Behçet's disease (BD) is HLA-B*51. Our group previously reported that HLA-A*26 is independently associated with the risk of the onset of BD apart from HLA-B*51. Here, we re-evaluated the association between HLA-A*26 and BD in the Japanese population. We also performed a comprehensive literature search and meta-analyzed the extracted published data concerning the relationship between HLA-A*26 and BD to estimate the odds ratio (OR) of HLA-A*26 to BD. In this study, we genotyped 611 Japanese BD patients and 2,955 unrelated ethnically matched healthy controls. Genotyping results showed that the phenotype frequency of HLA-A*26 was higher in BD patients than in controls (OR = 2.12, 95% CI: 1.75-2.56). Furthermore, within the HLA-B*51-negative populations, the phenotype frequency of HLA-A*26 was significantly higher in BD patients than in controls (OR = 3.10, 95% CI: 2.43-3.95). Results obtained from meta-analysis combined with our data showed that the modified OR of HLA-A*26 became 1.80 (95% CI:1.58-2.06), whereas within the HLA-B*51-negative population, the modified OR became 4.02 (95% CI: 2.29-7.05). A subgroup analysis arranged by the geographical regions showed HLA-A*26 is in fact associated with the onset of BD in Northeast Asia (OR = 2.11, 95% CI: 1.75-2.56), but not in the Middle East or in Europe.