The influence of HLA-B51 on clinical manifestations among Japanese patients with Behçet's disease: A nationwide survey

Impact of HLA-B51 on Uveitis and Retinal Vasculitis: Data from the AIDA International Network Registries on Ocular Inflammatory Disorders

PURPOSE

The clinical relevance of human leukocyte antigen (HLA) subtypes such as HLA-B51 on Behçet's disease (BD)-related uveitis and non-infectious uveitis (NIU) unrelated to BD remains largely unknown.

METHODS

Data were prospectively collected from the International AIDA Network Registry for BD and for NIU. We assessed differences between groups (NIU unrelated to BD and positive for HLA-B51, BD-related uveitis positive for HLA-B51 and BD-related uveitis negative for HLA-B51) in terms of long-term ocular complications, visual acuity (VA) measured by best corrected visual acuity (BCVA), anatomical pattern, occurrence of retinal vasculitis (RV) and macular edema over time.

RESULTS

Records of 213 patients (341 eyes) were analyzed. No differences in complications were observed (p = 0.465). With regard to VA, a significant difference was detected in median BCVA (p = 0.046), which was not maintained after Bonferroni correction (p = 0.060). RV was significantly more prevalent in NIU-affected patients who tested positive for HLA-B51, irrespective of the systemic diagnosis of BD (p = 0.025). No differences emerged in the occurrence of macular edema (p = 0.99).

CONCLUSIONS

Patients with NIU testing positive for HLA-B51 exhibit an increased likelihood of RV throughout disease course, irrespective of a systemic diagnosis of BD. The rate of complications as well as VA are comparable between NIU cases unrelated to BD testing positive for HLA-B51 and uveitis associated with BD. Therefore, it is advisable to perform the HLA-B typing in patients with NIU or retinal vasculitis, even in the absence of typical BD features.

Behçet's Disease: A Comprehensive Review on the Role of HLA-B*51, Antigen Presentation, and Inflammatory Cascade

Behçet's disease (BD) is a complex, recurring inflammatory disorder with autoinflammatory and autoimmune components. This comprehensive review aims to explore BD's pathogenesis, focusing on established genetic factors. Studies reveal that HLA-B*51 is the primary genetic risk factor, but non-HLA genes (ERAP1, IL-10, IL23R/IL-12RB2), as well as innate immunity genes (FUT2, MICA, TLRs), also contribute. Genome-wide studies emphasize the significance of ERAP1 and HLA-I epistasis. These variants influence antigen presentation, enzymatic activity, and HLA-I peptidomes, potentially leading to distinct autoimmune responses. We conducted a systematic review of the literature to identify studies exploring the association between HLA-B*51 and BD and further highlighted the roles of innate and adaptive immunity in BD. Dysregulations in Th1/Th2 and Th17/Th1 ratios, heightened clonal cytotoxic (CD8+) T cells, and reduced T regulatory cells characterize BD's complex immune responses. Various immune cell types (neutrophils, γδ T cells, natural killer cells) further contribute by releasing cytokines (IL-17, IL-8, GM-CSF) that enhance neutrophil activation and mediate interactions between innate and adaptive immunity. In summary, this review advances our understanding of BD pathogenesis while acknowledging the research limitations. Further exploration of genetic interactions, immune dysregulation, and immune cell roles is crucial. Future studies may unveil novel diagnostic and therapeutic strategies, offering improved management for this complex disease.

Risk factors, clinical features and treatment of Behçet's disease uveitis

Behçet's disease is a systemic vasculitis frequently associated with intraocular inflammation. Recent findings identified independent clinical clusters in Behçet's disease, each involving distinct combinations of affected organs. Ocular Behçet's disease, mainly manifested as uveitis, is characterized as an independent cluster with a low likelihood of association with other system involvements, such as intestinal, cardiovascular, or central nervous system. A prevailing theory suggests that the pathogenesis of the disease is multifactorial, where a variety of genetic and infectious agents may interact with each other to cause the disease. Among sporadic cases, the human leukocyte antigen (HLA) genes, including HLA-B51, HLA-A26, HLA-B15, and HLA-B5701, have been found to be a key component conferring genetic susceptibility. Outside the HLA region, a set of susceptibility variants are identified, closely related to interleukin (IL)-23/IL-17 pathway, tumor necrosis factor (TNF) signaling, and pattern recognition receptor systems. Microbial infections, such as Streptococcus sanguinis, Mycobacterium tuberculosis, and Herpes simplex virus (HSV), are linked to play the triggering of disease in immunogenetically predisposed individuals. Clinically, due to the notable relapsing-remitting course of ocular Behçet's disease, the prevention of recurrent attack would be the primary treatment goal. Combination of corticosteroids and immunomodulatory drugs, such as anti-TNF agents, interferon, and conventional immunosuppressants (e.g. cyclosporine, azathioprine), have been the mainstream regimen for the disease. Future research may focus on comparing the effectiveness of immunomodulatory drugs and identifying the most suitable subgroups for a specific drug on the basis of the knowledge of the molecular heterogeneity of the disease.

HLA Alleles in a Behçet Disease Multiethnic Population With and Without Ophthalmic Manifestations

OBJECTIVE

The aim of this study was to analyze HLA alleles in patients with Behçet disease (BD) and their correlation with ophthalmic manifestations (OMs) in a multiethnic Brazilian population.

METHODS

This case-control study compared 72 BD patients with or without OM who underwent a thorough ophthalmologic evaluation, including best-corrected visual acuity, bino-ophthalmoscopy, and HLA analysis, with 144 matched healthy controls. Fluorescein angiography was also performed in the patients with BD and OM. HLA class I (A, B, and C) and II (DRB1, DQB1, and DQA1) typing were performed using PCR-SSO.

RESULTS

Of 72 patients with BD, 42 (58%) had OM. The HLA-B*51 and -A*26 alleles were more frequent in patients with BD than in controls (23.6% vs 14.6% and 12.5% vs 4.3%, respectively), but could not differentiate OM risk. The HLA alleles of BD patients that differentiated those with and without OM were HLA-B*15 (40.5% vs 20.7%; odds ratio [OR], 2.59; p = 0.0059), HLA-C*02 (33.3% vs 13.4%; OR, 3.20; p = 0.0024), and HLA-DQB1*03 (64.3% vs 45.7%, p = 0.017), whereas HLA-A*03 (0.0% vs 13.3%, p = 0.006) and HLA-DRB1*15 (4.8% vs 19.5%; OR, 0.21; p = 0.0121) were protective against OM.

CONCLUSIONS

In this study of a Brazilian multiethnic BD population, alleles were similar between groups of BD patients with and without OM. We described HLA-B*15, -C*02, and -DQB1*03 as risk factors and -A*03 and -DRB1*15 as protective factors for OM in BD, which could function as biomarkers for predicting disease phenotypes.

Evaluation of HLA-B51 frequency and its relationship with clinical findings in patients with Behçet’s disease: 4-year analysis in a single center

Background

The clinical findings of Behçet’s disease (BD) differ according to the country and race investigated. The most important genetic factor known in the pathogenesis of BD is HLA-B51, and this positivity is high in countries on the “Silk Road” where BD is as frequent as it is in Turkey. Although the positivity of HLA B51 is proven to be high in Turkey, there are no studies in the area of the western Black sea demonstrating its relation to the demographic. We aimed to investigate the association of HLA-B51 positivity in Turkish patients diagnosed as having BD and the relationship between the demographic and clinical findings of the patients.

Results

In this descriptive, cross-sectional study, a convenience sample of adults with BD was obtained from an outpatient clinic of a university hospital in Turkey between January 2018 and January 2022. Patients were diagnosed as having BD according to the criteria of the International BD Study Group, and the patients’ sociodemographic and clinical characteristics were recorded retrospectively. Demographic data and the frequency of clinical findings were compared between patients who were HLA-B51-positive and HLA-B51-negative. Sixty patients (55.6%) were HLA-B51-positive. Oral ulceration, genital ulceration, thrombophlebitis, and family history of BD were found to be higher in patients who were HLA-B51-positive. Erythema nodosum, papulopustular eruption, pathergy positivity, arthritis, and ocular involvement were less frequent in patients with HLA-B51 positivity. However, there were no statistically significant differences according to the frequency of clinical findings between the HLA-B51-positive and HLA-B51-negative groups.

Conclusions

HLA B51 positivity is not diagnostic of BD; however, it may affect clinical phenotypes. Although oral and genital ulcerations, thrombophlebitis, and positive family history of BD were found to be common in patients with HLA-B51 positivity, this relationship could not reach statistical significance.

The association of Behçet's syndrome with HLA-B51 as understood in 2021

PURPOSE OF REVIEW

To discuss clinical and pathogenic roles of HLA-B∗51 in Behçet's syndrome.

RECENT FINDINGS

HLA-B∗51 remains the most important genetic factor in Behçet's syndrome, despite the recent identification of several susceptibility genes. The prevalence of HLA-B∗51 has been shown to differ among phenotype-based clinical clusters in the same patient population. HLA-B∗51 shows epistatic interaction with the susceptible allele of endoplasmic reticulum aminopeptidase (ERAP)1 encoding the Hap10 allotype, which has the lowest trimming activity of the MHC-Class I binding peptides. Subsequent molecular studies have suggested that the disease-associated Hap10 allotype is implicated in the generation and selection of the disease protective or promoting peptides loading onto HLA-B∗51, although these pathogenic peptides have yet to be identified.

SUMMARY

HLA-B∗51 is a hallmark of Behçet's syndrome but genetic markers are not very useful in the diagnosis of Behçet's syndrome. Rather, it is considered an important factor in determining clinical phenotypes in this heterogeneous condition. The epigenetic interaction of HLA-B∗51 with ERAP1 sheds light on pathogenesis.

Skin manifestation as an explaining factor of heterogeneity in Behçet's disease: A focused analysis in full-blown conditions

Behçet's disease (BD), a chronic multi-systemic disorder, presents diverse clinical manifestations depending on patient ethnicity and geographic region. Use of varying diagnostic criteria augments clinical heterogeneity. We aimed to characterize heterogenous manifestations in patients with full-blown BD fulfilling the major diagnostic criteria in use. We retrospectively analyzed 338 patients diagnosed with complete BD based on Japanese diagnostic criteria, which fulfill both International Study Group (ISG) criteria and the International Criteria for BD (ICBD). Unbiased clustering analysis was performed to elucidate the heterogeneous spectrum, followed by subgroup analysis of identified clusters. Results of unbiased clustering analysis identify dominant skin lesion type as an important factor that determines clustering among the heterogenous BD patients. Regression analysis reveals that presence of predominantly papulopustular lesions has protective effect for vascular involvement compared to other skin phenotypes. In conclusion, unbiased clustering analysis highlights that dermatologic manifestation can be a factor to understand the heterogeneity of BD and determining the dominant type of skin lesions may help clinicians predict major vascular involvement.

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.

Behçet syndrome

Behçet syndrome is a systemic vasculitis with an unknown aetiology affecting the small and large vessels of the venous and arterial systems. The presence of symptom clusters, regional differences in disease expression and similarities with, for example, Crohn's disease suggest that multiple pathological pathways are involved in Behçet syndrome. These disease features also make formulating disease criteria difficult. Genetic studies have identified HLA-B*51 as a genetic risk factor. However, the low prevalence of HLA-B*51 in many patients with bona fide disease, especially in non-endemic regions, suggests that other factors must also be operative in Behçet syndrome. Despite lacking a clear aetiological mechanism and definition, management of manifestations that include major vascular disease, eye disease and central nervous system involvement has improved with the help of new technology. Furthermore, even with our incomplete understanding of disease mechanisms, the prognoses of patients with Behçet syndrome, including those with eye disease, continue to improve. New treatment options and a better understanding of the underlying pathogenesis for various manifestations of this condition are required to further improve the management of the disease, which will improve patient quality of life.

Analysis of vascular involvement in 460 patients with Behçet's syndrome: Clinical characteristics and associated factors

OBJECTIVES

To describe demographic and clinical characteristics of vascular involvement in patients with Behçet's syndrome (BS) and to evaluate associations with such involvement.

METHODS

We retrospectively evaluated records of 2118 BS patients. In total, 460 patients diagnosed with superficial thrombophlebitis (ST) and/or major vascular events (venous and/or arterial involvements) were included in current analysis. Isolated ST with no accompanying deep venous thrombosis might be accepted as part of skin involvement; therefore, we defined two different outcomes for vascular involvement ("any vascular event" and "major vascular events") and performed univariable and multivariable logistic regression to assess factors associated with these outcome variables.

RESULTS

Overall, 68 (14.8%) patients had isolated ST, and 392 (85.2%) had major vascular events. The mean age of vascular BS was 33.8 (SD: 10.5) years and median follow-up was 13.9 (Q1-Q3: 8.3-22.9) years. The primary sites of major vascular events were deep venous thrombosis (n=358, 77.8%), pulmonary arterial involvement (n=66, 14.3%), extrapulmonary arterial involvement (n=52, 11.3%), and intracardiac thrombosis (n=14, 3.0%), respectively. Male sex was significantly associated with a higher risk for both outcome variables. When it was added to analysis, ST itself was the strongest explanatory variable that was associated with major vascular events in all multivariable models (ORs=11.9, 12.0, 13.0, and 18.9). While HLA-B51 was significantly associated with any vascular event, there was no similar observation for major vascular events.

CONCLUSION

Male sex is a well-known risk factor for major vascular events in BS, but our study established that presence of ST was the strongest risk factor.

A Contemporary Review of Behcet's Syndrome

Behcet's syndrome (BS) is a chronic systemic inflammatory vasculitis with a wide range of clinical manifestations including recurrent oral and genital ulcers; cutaneous lesions; and ophthalmic, neurologic, and gastrointestinal involvement. BS has a global distribution but is particularly prevalent in so-called Silk Road populations. Disease onset is usually around the third or fourth decade of life, and the sex ratio is roughly 1:1. Both environmental and genetic factors contribute to the etiology of BS, although the detailed mechanisms remain unclear. At present, there is no laboratory examination with diagnostic value for BS; therefore, a diagnosis is made based on clinical manifestations. The International Study Group diagnostic criteria published in 1990 is the most widely used and recognized, but in order to improve sensitivity, the International Criteria for Behcet's Disease is developed in 2014. Evaluating disease activity in BS is an important basis for treatment selection and monitoring, the simplified Behcet's Disease Current Activity Form (2006 version) is a well-established scoring method. Given that multiple organs are affected in BS, it must be differentiated from other diseases with similar manifestations or that may be induced by drug treatment. The goal of BS treatment is to eradicate triggers and/or aggravating factors, alleviate and control clinical symptoms, prevent and treat any damage to organs, slow disease progression, and improve the patient's quality of life. The clinical management of BS depends on the affected organs and disease severity. In this review, we summarize the current state of knowledge of BS pathogenesis and therapeutic options.

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.

Changes in the proportion of clinical clusters contribute to the phenotypic evolution of Behçet's disease in Japan

Background

We hypothesized that Behçet’s disease (BD) consists of several clinical subtypes with different severity, resulting in heterogeneity of the disease. Here, we conducted a study to identify clinical clusters of BD.

Methods

A total of 657 patients registered in the Yokohama City University (YCU) regional BD registry between 1990 and 2018, as well as 6754 patients who were initially registered in the Japanese Ministry of Health, Labour and Welfare (MHLW) database between 2003 and 2014, were investigated. The YCU registry data regarding the clinical manifestations of BD, human leukocyte antigen (HLA) status, treatments, and hospitalizations were analyzed first, followed by similar analyses of the MHLW for validation. A hierarchical cluster analysis was independently performed in both patient groups.

Results

A hierarchical cluster analysis determined five independent clinical clusters in the YCU cohort. Individual counterparts of the YCU clusters were confirmed in the MHLW registry. Recent phenotypical evolutions of BD in Japan, such as increased gastrointestinal (GI) involvement, reduced complete type according to the Japan Criteria, and reduced HLA-B51 positivity were associated with chronologically changing proportions of the clinical clusters.

Conclusions

In this study, we identified independent clinical clusters among BD patients in Japan and found that the proportion of each cluster varied over time. We propose five independent clusters namely “mucocutaneous”, “mucocutaneous with arthritis”, “neuro”, “GI”, and “eye.”

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.