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

Significant association of HLA-A26 with uveitis and gastrointestinal involvement in patients with Behçet's disease in a multicentre study

OBJECTIVES

Specific human leukocyte antigen (HLA) haplotypes are associated with Behçet's disease. Because the effects of HLA-A26 and its combination with HLA-B51 on organ involvement in Behçet's disease have not been well demonstrated, we aimed to examine them.

METHODS

This multicentre, cross-sectional, observational study enrolled patients with Behçet's disease who visited Kyoto University Hospital between 2018 and 2021 or Kurashiki Central Hospital between 2006 and 2016 (n = 200). Disease severity was evaluated using the Krause score.

RESULTS

Uveitis and gastrointestinal involvement were observed in 95/196 and 57/167 patients, respectively. The HLA alleles identified were HLA-B51 (n = 52/106), HLA-A26 (n = 25/88), and HLA-B51 and HLA-A26 (n = 6/88). In patients harbouring HLA-B51, the presence of HLA-A26 was associated with higher frequencies of uveitis (P = .03) and coexistence of uveitis and gastrointestinal involvement (P = .002) and higher Krause scores (P = .02). Furthermore, the presence of HLA-A26 was associated with a higher frequency of uveitis in patients with gastrointestinal involvement (P = .001) and gastrointestinal involvement in patients with uveitis (P = .001).

CONCLUSIONS

Since specific HLA haplotypes and their combinations are associated with organ involvement, both HLA-A and HLA-B haplotypes should be confirmed when screening for affected organs.

High Resolution HLA-A, HLA-B, and HLA-C Allele Frequencies in Romanian Hematopoietic Stem Cell Donors

The HLA genes are associated with various autoimmune pathologies, with the control of the immune response also being significant in organs and cells transplantation. The aim of the study is to identify the HLA-A, HLA-B, and HLA-C alleles frequencies in the analyzed Romanian cohort. We performed HLA typing using next-generation sequencing (NGS) in a Romanian cohort to estimate class I HLA allele frequencies up to a six-digit resolution. A total of 420 voluntary donors from the National Registry of Voluntary Hematopoietic Stem Cell Donors (RNDVCSH) were included in the study for HLA genotyping. Peripheral blood samples were taken and brought to the Fundeni Clinical Institute during 2020-2021. HLA genotyping was performed using the Immucor Mia Fora NGS MFlex kit. A total of 109 different alleles were detected in 420 analyzed samples, out of which 31 were for HLA-A, 49 for HLA-B, and 29 for HLA-C. The most frequent HLA-A alleles were HLA-A*02:01:01 (26.11%), HLA-A*01:01:01 (12.5%), HLA-A*24:02:01 (11.67%), HLA-A*03:01:01 (9.72%), HLA-A*11:01:01, and HLA-A*32:01:01 (each with 8.6%). For the HLA-B locus, the most frequent allele was HLA-B*18:01:01 (11.25%), followed by HLA-B*51:01:01 (10.83%) and HLA-B*08:01:01 (7.78%). The most common HLA-C alleles were HLA-C*07:01:01 (17.36%), HLA-C*04:01:01 (13.47%), and HLA-C*12:03:01 (10.69%). Follow-up studies are ongoing for confirming the detected results.

Unique presentation of acute neuro-Behçet's disease involving a cytotoxic edema core surrounded by vasogenic edema

A 53-year-old woman with recurrent stomatitis, genital ulcers, and folliculitis was admitted to our hospital after experiencing visual disturbances for the past two weeks, and a non-throbbing headache for the past three days. She had also developed numbness in her left extremities. An ophthalmological examination revealed inflammatory changes in the eye. Cerebrospinal fluid analysis showed increased cell counts, protein, and interleukin-6 levels. Brain magnetic resonance imaging revealed multiple high signal intensities on T2-weighted (T2W)/fluid-attenuated inversion recovery (FLAIR) images of the pons and occipital and parietal lobes. The T2W/FLAIR high-signal-intensity lesion in the pons was hyperintense on diffusion-weighted imaging (DWI) and hypointense on apparent diffusion coefficient mapping (ADC), suggesting cytotoxic edema. Another high-signal-intensity lesion on T2W/FLAIR was isointense to hyperintense on DWI and hyperintense on ADC, indicating vasogenic edema. The vasogenic edema in the left occipital lobe contained a small core that was hyperintense on DWI and hypointense on ADC, suggesting cytotoxic edema. The patient was diagnosed with acute neuro-Behçet's disease (neuro-BD) and responded well to high-dose glucocorticoid and colchicine treatment. The present report emphasizes that patients with acute neuro-BD may present with cytotoxic edema in the pons and cerebral spheres. Further reports of similar cases would contribute to a better understanding of the role of cytotoxic edema in the pathophysiology of neuro-BD and help elucidate the mechanisms underlying a unique presentation characterized by a central cytotoxic edema core within vasogenic edema. (233 words).

Replication Study of the Association of GAS6 and PROS1 Polymorphisms with Behçet's Disease in a Japanese Population

PURPOSE

To investigate whether polymorphisms of GAS6 and PROS1, which each encode protein ligands for a family of tyrosine kinase receptors, are associated with Behçet's disease (BD) in a Japanese population.

METHODS

We recruited 734 Japanese patients with BD and 1789 Japanese healthy controls. In all participants, we genotyped two single-nucleotide polymorphisms (SNPs) reportedly associated with BD: rs9577873 in GAS6 and rs4857037 in PROS1.

RESULTS

We found that GAS6 rs9577873 was not significantly associated with BD. In contrast, PROS1 rs4857037, specifically the A allele, was associated with increased risk for BD. The A allele was also significantly associated with BD under additive and recessive genetic models. Expression analysis revealed that this allele was significantly associated with increased PROS1 expression.

CONCLUSIONS

Our findings suggest that increased PROS1 expression related to the A risk allele of rs4857037 affects tyrosine kinase receptor signaling, contributing to the development of BD.

HLA-B*51 Frequency in Transplant Patients and Donors

OBJECTIVES

HLA molecules play a crucial role in transplantation. The best treatment modality in patients with end-stage renal disease is renal transplant. HLA mismatches between patients and donors can prolong time for renal transplant therapy, reduce graft survival, and increase mortality. HLA region is the most polymorphic genetic region and is essential for antigen presentation. The main target of the recipient's immune system is HLA molecules on the surface of donor cells. HLA-B*51 is associated with Behcet disease, a rare multisystemic disease characterized by autoimmunity and inflammatory processes. In transplant recipients, inflammation and vasculitis are immunologic mechanisms that are responsible for damage of graft tissue. In this retrospective study, we aimed to investigate the frequency of HLA-B*51 in patients diagnosed with end-stage renal disease and in controls and to investigate correlations with rejection episodes.

MATERIALS AND METHODS

Patients who applied to Baskent University Adana Dr. Turgut Noyan Research and Medical Center (between 2010 and 2022) with end-stage renal disease (n = 1732) and a control group (n = 5277) received HLA typing for class I (HLA-A, HLA-B). Sequence-specific primers or sequencespecific oligonucleotides were used. Among patients diagnosed with end-stage renal disease, 321 had kidney transplant.

RESULTS

Frequency of HLA-B*51 was 25.92% in patients and 25.22% in controls. No significant differences were found between patients and controls in the frequency of HLA-B*51. Among kidney transplant recipients with HLA-B*51 (n = 72), 38.89% had rejection episodes and 61.11% had no rejection. No significant association was found between HLA-B*51 allele positivity and rejection.

CONCLUSIONS

No significant relationship was shown between patients diagnosed with end-stage renal disease and HLA-B*51 positivity. Previous studies support frequency of the HLA-B*51 allele in the control group. Although Behçet disease is known to cause renal vasculitis, HLA-B*51 positivity alone was not associated with vasculitis or inflammation.

Advances in pathogenesis and treatment of ocular involvement in Behcet's disease

Behcet's disease (BD) is a chronic multi-systemic disease characterized by relapsing-remitting oral ulcers, genital ulcers, ocular inflammatory involvements, and numerous other systemic features. Ocular involvements are quite common in BD and may cause severe tissue damage and potentially blindness. Even though the pathogenesis of BD remains ambiguous, growing evidences have shown that genetic factors, environmental triggers and immunological abnormalities play significant roles in its development and progression. Novel biotherapies targeting IFN-γ, TNF-α and interleukins have been used in recent years. In this review, we mainly pay attention to the ocular involvement of BD, and discuss the current understanding of mechanisms and advances in therapeutic approaches, especially novel biologics. Finally, we discuss the management in patients with pregnancy.

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.

Association of long non-coding RNAs NEAT1, and MALAT1 expression and pathogenesis of Behçet's disease among Egyptian patients

Behçet's disease (BD) is a chronic inflammatory disease. Immunological defects have been shown to play a significant role in the progression of BD. The serum levels of two long non-coding RNAs (lncRNAs), NEAT1 and MALAT1, were examined in patients with BD to identify their role in the disease pathogenesis. Both lncRNAs were mentioned as essential regulators of innate immune responses and have a crucial role in inflammatory diseases. Fifty patients with BD and a similar number of control individuals were involved in our study. At enrollment, data was collected from patients and controls, and the disease severity in active cases was determined using the Behçet's Disease Current Activity Form (BDCAF). Levels of the two studied biomarkers in the serum, NEAT1 and MALAT1, were investigated by quantitative RT-PCR (qRT-PCR). NEAT1 levels were significantly turned down in BD patients (fold changes = 0.77, p = 0.0001) and correlated negatively with the BDCAF (r = −0.41; p = 0.003). On the other hand, the MALAT1 levels were significantly up-regulated in BD patients (fold changes = 2.65, p = 0.003). Serum levels of NEAT1 were significantly decreased in patients with active states than in stationary cases (0.387 versus 1.99, respectively; p = 0.01) and compared with controls (p = 0.001). Also, NEAT1 levels were significantly increased in patients with stationary states compared to controls (p = 0.03). There was a positive association between NEAT1 and MALAT1 levels among BD patients (r = 0.29, p = 0.04). Our findings demonstrate a possible role of NEAT1 and MALAT1 in the pathogenesis of BD.

Natural LILRB1 D1-D2 variants show frequency differences in populations and bind to HLA class I with various avidities

Leukocyte immunoglobulin-like receptor B1 (LILRB1) is widely expressed on various immune cells and the engagement of LILRB1 to HLA class I and pathogen-derived proteins can modulate the immune response. In the current study, 108 LILRB1 alleles were identified by screening the LILRB1 locus from the 1000 Genomes Phase 3 database. Forty-six alleles that occurred in three or more individuals encode 28 LILRB1 allotypes, and the inferred LILRB1 allotypes were then grouped into 9 LILRB1 D1-D2 variants for further analysis. We found that variants 1, 2, and 3 represent the three most frequent LILRB1 D1-D2 variants and the nine variants show frequency differences in populations. The binding assay demonstrated that variant 1 bound to HLA class I with the highest avidity, and all tested LILRB1 D1-D2 variants bound to HLA-C with lower avidity than to HLA-A and -B. Locus-specific polymorphisms at positions 183, 189, and 268 in HLA class I and dimorphisms in HLA-A (positions 207 and 253) and in HLA-B (position 194) affect their binding to LILRB1. Notably, the electrostatic interaction plays a critical role in the binding of LILRB1 to HLA class I as revealed by electrostatic analysis and by comparison of different binding avidities caused by polymorphisms at positions 72 and 103 of LILRB1. In this paper, we present a comprehensive study of the population genetics and binding abilities of LILRB1. The data will help us better understand the LILRB1-related diversity of the immune system and lay a foundation for functional studies.

Critical Role of Gut Microbiota and Epigenetic Factors in the Pathogenesis of Behçet's Disease

Behçet’s disease (BD) is a chronic refractory multisystem autoinflammatory disease, characterized by typical clinical features of non-specific vasculitis, oral and genital ulcers, uveitis, as well as skin lesions. The exact etiopathogenesis of BD remains unknown, existing studies have indicated that genetics and environmental factors contribute to the increased development of BD. Recently, several studies have shown that external environmental factors can affect the process of epigenetic modification, and abnormalities of epigenetic factors have been confirmed to be involved in the occurrence of BD. At the same time, abnormalities of gut microbiota (GM) in the body, have also been confirmed to participate in the pathogenesis of BD by regulating the balance of Th17/Tregs. This article reviews the pathogenesis of BD and summarizes numerous clinical studies, focusing on the mechanism of GM and epigenetic factors impacting on BD, and providing new ideas for further elucidating the pathogenesis of BD.

Epidemiologic and Etiological Features of Korean Patients With Behçet's Disease

Behçet's disease (BD) is a multisystem disease in which environmental factors provoke an adverse immune response in patients with genetic susceptibility towards BD, subsequently leading to a cascade of dysregulated inflammation throughout the body. It is particularly prevalent in regions spanning the ancient Silk Road, including Korea, where the first known case of BD was reported in 1961. We summarize the history, epidemiology, and clinical presentation of BD in Korea, highlighting the clinical tendencies that are particularly seen in the Korean BD population as compared to European populations. Analysis of epidemiologic trends over the past three decades in Korea shows a decreasing prevalence of complete BD and a higher prevalence of intestinal BD. We also discuss the ever-evolving understanding of the pathogenesis of BD, noting the complex interplay among genetics, environment, and immunology. The HLA-B51 allele is the most significant known genetic risk factor in developing BD. We also discuss more recently studied associations between BD and immune factors such as IL-10, IL-23R-IL-12RB2, IL-1A-IL-1B, CCR1, ERAP1, and the GIMAP cluster, the last of which has been found to have an association with BD specifically in Korea. Environmental factors such as pollution and microbials are often the inciting event in developing BD, as they trigger an imbalanced immune response in genetically susceptible individuals, one that has been often found to exhibit an aberrant Th1/Th17 response. There would be value to further studying the pathogenesis and clinical characteristics of Korean BD.

Current research status of HLA in immune-related diseases

Human leukocyte antigen (HLA), also known as human major histocompatibility complex (MHC), is encoded by the HLA gene complex, and is currently known to have the highest gene density and the most polymorphisms among human chromosomal areas. HLA is divided into class I antigens, class II antigens, and class III antigens according to distribution and function. Classical HLA class I antigens include HLA-A, HLA-B, and HLA-C; HLA class II antigens include HLA-DP, HLA-DQ, and HLA-DR; nonclassical HLA class I and II molecules include HLA-F, E, H, X, DN, DO, and DM; and others, such as complement, are class III antigens. HLA is closely related to the body's immune response, regulation, and surveillance and is of great significance in the study of autoimmune diseases, tumor immunity, organ transplantation, and reproductive immunity. HLA is an important research topic that bridges immunology and clinical diseases. With the development of research methods and technologies, there will be more discoveries and broader prospects.

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.

Integrated proteome and phosphoproteome analyses of peripheral blood mononuclear cells in primary Sjögren syndrome patients

Primary Sjögren syndrome (pSS) is a common autoimmune disease. Here, we performed the first proteome and phosphoproteome analyses of peripheral blood mononuclear cells in pSS patients to obtain a comprehensive profile and identify the potential crucial proteins and pathways for the screening and evaluation of pSS patients. Peripheral blood mononuclear cells from 8 pSS-confirmed patients (American-European Consensus Group Criteria, 2002) and 10 normal controls were selected. Label-free quantitative proteomics was utilized to obtain quantitative information. In total, 787 proteins were identified as differentially expressed proteins, and 175 phosphosites on 123 proteins were identified as differentially phosphorylated proteins. We performed functional enrichment analyses with these proteins and phosphoproteins based on public database. Furthermore, protein-protein interaction network analyses were performed by using multiple algorithms. Using module and hub protein analyses, we identified 16 modules for the proteins, 2 clusters for the phosphoproteins and selected the top 10 hub proteins. Finally, we identified 22 motifs using motif analysis of the phosphosites and found 17 newly identified motifs, while 6 motifs were experimentally verified for known protein kinases. The findings distinguished pSS patients from normal controls at the peripheral blood mononuclear cells level and revealed potential candidates for use in pSS diagnosis.

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.

HLA-A26 is a risk factor for Behçet's disease ocular lesions

BACKGROUND

How HLA-A26 modulates Behçet's disease (BD) ocular lesions such as iridocyclitis and retinochorioiditis has not been scrutinized.

METHODS

Ministry of Health, Labour and Welfare of Japan provided us a database of BD patients who were registered from 2003 to 2014. We selected patients who satisfied International Criteria for BD and whose data for HLA-A26 was available.

RESULTS

Eligible 557 patients consisting of 238 men (42.7%) and 319 women (57.3%), whose median age was 38 years old (interquartile range 29-47) were analyzed. Prevalence of general ocular lesions, iridocyclitis, retinochorioiditis, and chronic lesions were 43.1%, 30.7%, 34.1%, and 17.4%, respectively. The prevalence of ocular lesions was higher among HLA-A26 carriers compared to that among HLA-A26 non-carriers with odds ratio (OR) of 2.5 (95% confidence interval (95% CI) 1.8-3.5, p < .001) for general ocular lesions, OR of 2.5 (95% CI 1.7-3.6, p < .001) for iridocyclitis, OR of 2.8 (95% CI 1.9-4.0, p < .001) for retinochorioiditis, and OR of 2.7 (95% CI 1.7-4.3, p < .001) for 'chronic ocular lesion following iridocyclitis or retinochorioiditis'. The HLA-A26 had a similar impact on ocular lesions between HLA-B51 positive and negative cases (Breslow-Day test, p > .05). However, the HLA-A26 had a larger impact on iridocyclitis for men compared to women (Breslow-Day test, p = .040). The male HLA-A26 carriers had higher risk of iridocyclitis with OR of 3.4 (95% CI 2.0-5.9, p < .001), while the OR for women was 1.5 (95% CI 0.9-2.6, p = .146).

CONCLUSION

HLA-A26 carriers had higher risk for iridocyclitis and retinochorioiditis. However, the impact was more prominent for men.

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.