Is Behçet's disease a 'class 1-opathy'? The role of HLA-B*51 in the pathogenesis of Behçet's disease

[An update on Behçet's syndrome]

Behçet's syndrome (BS, synonym: Behçet's disease, or Adamantiades-Behçet's disease, ABD) is classified as a vasculitis of variable vessel size and can manifest itself in both arterial and venous vessels. Its extensive and at the same time interindividually very different clinical picture is not uncommon a challenge, both with regard to the diagnosis of this rheumatic systemic disease, which is rather rare in our latitudes, and its therapeutic options. In addition to the four cardinal symptoms of recurrent oral aphthae, genital aphthae, skin and eye lesions, the clinical picture offers numerous other manifestations which often require interdisciplinary cooperation. In addition to the above mentioned ocular involvement, which can still lead to blindness if inadequately treated, this is especially true for intestinal and cerebral manifestations as well as for large vessel vasculitis.A final revision of the European League Against Rheumatism recommendations for the management of Behcet's syndrome (EULAR) was made in 2018, and the recommendations are now established internationally as an important treatment guide. Therapy is based on the leading organ involvement. After adalimumab received approval for the treatment of posterior ocular involvement in 2016, another agent, apremilast, became available in 2020. The drug is recommended for the treatment of recurrent oral aphthae in adult Behçet's patients requiring systemic therapy. Nevertheless, there is a further need for new drugs.This article aims to highlight recent findings in the areas of epidemiology, immunopathogenesis & genetics, clinical findings, and therapy, with an emphasis on clinical relevance.

[The role of HLA-B27 in the pathogenesis and diagnosis of axial spondyloarthritis : 50 years after discovery of the strong genetic association]

BACKGROUND

The association of the human lymphocyte antigen B27 (HLA-B27) with ankylosing spondylitis (AS), also now called axial spondylarthritis (axSpA), was first described 50 years ago.

OBJECTIVE

This article gives an overview of the available knowledge on the topic.

MATERIAL AND METHODS

This is a narrative review based on the experience of the authors.

RESULTS

The HLA-B27 is a member of the HLA class I family of genes of the major histocompatibility complex (MHC). The prevalence of HLA-B27 in the central European population is approximately 8 %, i.e., the vast majority of carriers of HLA-B27+ remain healthy. The frequency of HLA-B27 shows a decline from north to south. The HLA-B27 explains only 30 % of the genetic burden of axSpA. The prevalence of the disease correlates with the frequency of HLA-B27 in the population, i.e., there are geographic differences. Approximately 60-90 % of patients with axSpA worldwide are HLA-B27+. Some 200 subtypes of HLA-B27 can be differentiated using the polymerase chain reaction (PCR). In Thailand and Sardinia two subtypes were found that are not associated with axSpA. The physiological function of HLA class I molecules is the defence of the organism against microbes. Microbial peptides are presented to the immune system, which can be specifically attacked by CD8+ T‑cells. Genetic polymorphisms of the enzyme endoplasmic reticulum aminopeptidase 1 (ERAP1), which breaks down peptides in the endoplasmic reticulum, are associated only with HLA-B27+ diseases.

DISCUSSION

The pathogenesis of axSpA is unclear but a major hypothesis is that of the arthritogenic peptides. In this it is assumed that potentially pathogenic foreign or autologous peptides can be presented by HLA-B27. If nothing else, HLA-B27 plays an important role in the diagnosis, classification and determination of the severity of axSpA.

Neutrophil extracellular traps and neutrophilic dermatosis: an update review

Neutrophils have both antimicrobial ability and pathogenic effect in the immune system, neutrophil extracellular traps (NETs) formation is one of the representative behaviors of their dual role. NETs formation was triggered by pathogen-related components and pathogen non-related proteins as cytokines to exert its effector functions. Recent studies indicate that the pathogenicity of NETs contributed to several skin diseases such as psoriasis, Stevens-Johnson syndrome, toxic epidermal necrolysis, and neutrophilic dermatosis. Especially in neutrophilic dermatosis, a heterogeneous group of inflammatory skin disorders characterized with sterile neutrophilic infiltrate on dermis, NETs formation was reported as the way of participation of neutrophils in the pathogenesis of these diseases. In this review, we describe the different processes of NETs formation, then summarized the most recent updates about the pathogenesis of neutrophilic dermatosis and the participation of NETs, including pyoderma gangrenosum and PAPA syndrome, Behçet syndrome, hidradenitis suppurativa, Sweet Syndrome, pustular dermatosis and other neutrophilic dermatosis. Furthermore, we discuss the link between NETs formation and the development of neutrophilic dermatosis.

Genetic testing of Behçet's disease using next-generation sequencing to identify monogenic mimics and HLA-B*51

OBJECTIVE

Several monogenic autoinflammatory disorders and primary immunodeficiencies can present early in life with features that may be mistaken for Behçet's disease (BD). We aimed to develop a genetic analysis workflow to identify rare monogenic BD-like diseases and establish the contribution of HLA haplotype in a cohort of patients from the UK.

METHODS

Patients with clinically suspected BD were recruited from four BD specialist care centres in the UK. All participants underwent whole exome sequencing (WES), and genetic analysis thereafter by 1. examining genes known to cause monogenic immunodeficiency, autoinflammation or vasculitis by virtual panel application; 2. scrutiny of variants prioritised by Exomiser using Human Phenotype Ontology (HPO); 3. identification of copy number variants using ExomeDepth; and 4. HLA-typing using OptiType.

RESULTS

Thirty-one patients were recruited: median age 15 (4-52), and median disease onset age 5 (0-20). Nine/31 (29%) patients had monogenic disease mimicking BD: 5 cases of Haploinsufficiency of A20 with novel TNFAIP3 variants (p.T76I, p.M112Tfs*8, p.S548Dfs*128, p.C657Vfs*14, p.E661Nfs*36); 1 case of ISG15 deficiency with a novel nonsense variant (ISG15:p.Q16X) and 1p36.33 microdeletion; 1 case of Common variable immune deficiency (TNFRSF13B:p.A181E); and 2 cases of TNF receptor associated periodic syndrome (TNFRSF1A:p.R92Q). Of the remaining 22 patients, 8 (36%) were HLA-B*51 positive.

CONCLUSION

We describe a novel genetic workflow for BD, which can efficiently detect known and potentially novel monogenic forms of BD, whilst additionally providing HLA-typing. Our results highlight the importance of genetic testing before BD diagnosis, since this has impact on choice of therapy, prognosis, and genetic counselling.

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.

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.

[An update on Behçet's syndrome]

Behçet's syndrome (BS, synonym: Behçet's disease, or Adamantiades-Behçet's disease, ABD) is classified as a vasculitis of variable vessel size and can manifest itself in both arterial and venous vessels. Its extensive and at the same time interindividually very different clinical picture is not uncommon a challenge, both with regard to the diagnosis of this rheumatic systemic disease, which is rather rare in our latitudes, and its therapeutic options. In addition to the four cardinal symptoms of recurrent oral aphthae, genital aphthae, skin and eye lesions, the clinical picture offers numerous other manifestations which often require interdisciplinary cooperation. In addition to the above mentioned ocular involvement, which can still lead to blindness if inadequately treated, this is especially true for intestinal and cerebral manifestations as well as for large vessel vasculitis.A final revision of the European League Against Rheumatism recommendations for the management of Behcet's syndrome (EULAR) was made in 2018, and the recommendations are now established internationally as an important treatment guide. Therapy is based on the leading organ involvement. After adalimumab received approval for the treatment of posterior ocular involvement in 2016, another agent, apremilast, became available in 2020. The drug is recommended for the treatment of recurrent oral aphthae in adult Behçet's patients requiring systemic therapy. Nevertheless, there is a further need for new drugs.This article aims to highlight recent findings in the areas of epidemiology, immunopathogenesis & genetics, clinical findings, and therapy, with an emphasis on clinical relevance.

Fifty years after the discovery of the association of HLA B27 with ankylosing spondylitis

The human lymphocyte antigen B27 (HLA B27) is a member of the HLA class I family of genes in the major histocompatibility complex whose name goes back to its discovery in studies of transplanted tissue compatibility. Its prevalence in the mid-European population is about 8%. The association of HLA B27 alleles with ankylosing spondylitis (AS), a highly heritable disease, which is part of the spectrum of axial spondyloarthritis (axSpA), was discovered 50 years ago. HLA B27 explains less than 30% of the total genetic load. About 60%-90% of axSpA patients worldwide carry HLA B27. The prevalence of the disease is linked to the frequency of HLA B27 in the population which implies that there are relevant differences. Among the roughly 200 subtypes known there are two which are not disease associated. The function of HLA class I molecules is to present peptides to the immune system to defend the organism against microbes targeted by CD8+T cells. This is much supported by the role of the endoplasmic reticulum aminopeptidase 1 (ERAP 1) in AS, an enzyme that is responsible for the intracellular trimming of peptides, since polymorphisms of this gene are only associated with HLA-B27+ disease. The arthritogenic peptide hypothesis trying to explain the pathogenesis of AS is based on that very immune function assuming that also self peptides can be presented. HLA-B27 also plays an important role in classification, diagnosis and severitiy of axSpA.

Oral Lesions as the Primary Manifestations of Behçet's Disease: The Importance of Interdisciplinary Diagnostics-A Case Report

BACKGROUND

Behçet's disease (BD) is a rare chronic auto-inflammatory systemic disease with non-specific oral manifestations, categorised as generalised variable vessel vasculitis that requires an interdisciplinary approach to diagnose due to its phenotypic heterogeneity. Whilst the oral lesions that reoccur in BD underpin the complex diagnostic process, the crucial role of dental professionals is highlighted in a case report summarised herein. We present a case of a 47-year-old male referred to the Oral Medicine Department by a rheumatologist after previous hospitalization for thrombosis of the iliac vein and inferior vena cava. He had elevated inflammatory C-reactive protein biomarker and an increased erythrocyte sedimentation rate. Recurrent episodes of folliculitis, oral and genital ulcers were reported. Clinical examination revealed multiple ulcerations in the oral mucosa. The complementary, histopathological analysis performed to rule out other disorders, based on excisional biopsy, showed non-keratinised stratified squamous epithelium with areas of exocytosis and ulceration. The connective tissue presented an intense mixed inflammatory infiltrate, congested blood vessels, haemorrhage, vasculitis, and HLA-B genotyping identified the expression of HLA-B15, further supporting the BD diagnosis. Treatment was initiated with colchicine, prednisolone, and weekly subcutaneous administration of methotrexate and resulted in the complete remission of oral lesions and no recurrence of other manifestations.

CONCLUSIONS

This BD case report emphasizes the importance of a multidisciplinary approach in diagnosing BD, including the use of histopathological assessment and genetic profiling. It highlights the significance of thorough intraoral assessment and referral to a multidisciplinary team for diagnosis. The oral manifestations of BD as the primary symptoms often indicate underlying major systemic pathologies. The authors stress the need for a structured diagnostic algorithm to facilitate timely and effective management of BD.

EULAR study group on ‘MHC-I-opathy’: identifying disease-overarching mechanisms across disciplines and borders

The ‘MHC-I (major histocompatibility complex class I)-opathy’ concept describes a family of inflammatory conditions with overlapping clinical manifestations and a strong genetic link to the MHC-I antigen presentation pathway. Classical MHC-I-opathies such as spondyloarthritis, Behçet’s disease, psoriasis and birdshot uveitis are widely recognised for their strong association with certain MHC-I alleles and gene variants of the antigen processing aminopeptidases ERAP1 and ERAP2 that implicates altered MHC-I peptide presentation to CD8+T cells in the pathogenesis. Progress in understanding the cause and treatment of these disorders is hampered by patient phenotypic heterogeneity and lack of systematic investigation of the MHC-I pathway.

Here, we discuss new insights into the biology of MHC-I-opathies that strongly advocate for disease-overarching and integrated molecular and clinical investigation to decipher underlying disease mechanisms. Because this requires transformative multidisciplinary collaboration, we introduce the EULAR study group on MHC-I-opathies to unite clinical expertise in rheumatology, dermatology and ophthalmology, with fundamental and translational researchers from multiple disciplines such as immunology, genomics and proteomics, alongside patient partners. We prioritise standardisation of disease phenotypes and scientific nomenclature and propose interdisciplinary genetic and translational studies to exploit emerging therapeutic strategies to understand MHC-I-mediated disease mechanisms. These collaborative efforts are required to address outstanding questions in the etiopathogenesis of MHC-I-opathies towards improving patient treatment and prognostication.

Frail Silk: Is the Hughes-Stovin Syndrome a Behçet Syndrome Subtype with Aneurysm-Involved Gene Variants?

Hughes-Stovin syndrome is a rare disease characterized by thrombophlebitis and multiple pulmonary and/or bronchial aneurysms. The etiology and pathogenesis of HSS are incompletely known. The current consensus is that vasculitis underlies the pathogenic process, and pulmonary thrombosis follows arterial wall inflammation. As such, Hughes-Stovin syndrome may belong to the vascular cluster with lung involvement of Behçet syndrome, although oral aphtae, arthritis, and uveitis are rarely found. Behçet syndrome is a multifactorial polygenic disease with genetic, epigenetic, environmental, and mostly immunological contributors. The different Behçet syndrome phenotypes are presumably based upon different genetic determinants involving more than one pathogenic pathway. Hughes-Stovin syndrome may have common pathways with fibromuscular dysplasias and other diseases evolving with vascular aneurysms. We describe a Hughes-Stovin syndrome case fulfilling the Behçet syndrome criteria. A MYLK variant of unknown significance was detected, along with other heterozygous mutations in genes that may impact angiogenesis pathways. We discuss the possible involvement of these genetic findings, as well as other potential common determinants of Behçet/Hughes-Stovin syndrome and aneurysms in vascular Behçet syndrome. Recent advances in diagnostic techniques, including genetic testing, could help diagnose a specific Behçet syndrome subtype and other associated conditions to personalize the disease management.

The proportion of C1q-high and ISG15-high monocytes in the skin of patients with Behçet disease

Behçet disease (BD) is a chronic systemic vasculitis that is clinically characterized by recurrent oral ulcers, genital ulcers, uveitis, and skin lesions. Here, we conducted bulk RNA-seq of skin samples from 4 BD patients and 4 normal controls (NCs). A total of 260 differentially expressed genes (DEGs), including 99 upregulated and 161 downregulated genes, were detected in the skin lesions of BD patients compared to NCs. These DEGs were mainly enriched in the following biological processes: the activation and migration of immune cells, the release of proinflammatory factors, and the IFN-γ signaling pathway. The top upregulated DEGs were CXCL10, CXCL9, FCGR3A, GBP5, GBP4, LILRB2, ADIPOQ, PLIN1, SLC43A2, and MYO1G. Using the deconvolution method CIBERSORT, we analyzed the immune cells subtypes in the skin of BD by integrating the single cell RNA-seq data from PBMC (GSE198616) and bulk RNA-seq data of skin. There was a higher proportion of C1q+ and ISG15 + monocyte subtypes in skin of BD. IHC staining of CD14 and CD16 showed that the monocyte number increased in the skin of BD. IF staining confirmed there was a higher proportion of the C1Q + Mono and ISG15 + Mono subsets in the skin of BD patients. Moreover, we analyzed the average expression level of the top upregulated genes in immune cell types found in PBMC from BD patients and NCs. Almost all the top upregulated genes expressed in monocytes. CXCL10 was specifically expressed in ISG15 + monocyte, and GBP5, GBP4 and IFI44L were expressed more strongly in ISG15 + monocytes. LILRB2 was expressed more strongly in CD16⁺ monocytes and C1Q + monocytes. In conclusion, our study identified that the IFN-γ pathway was activated in skin of BD and the proportion of C1q+ and ISG15 + monocyte subtype increased in the skin of BD.

Association of miRNA-146a Gene Polymorphism Rs2910164 with Behcet's Disease: A Meta-analysis

BACKGROUND

A meta-analysis was performed by summarizing relevant researches to evaluate the relationship between miRNA-146a gene polymorphism rs2910164 and Behcet's disease (BD).

METHODS

A systematic search of published studies was conducted in PubMed and Embase. Five eligible studies involving 1167 BD cases and 1662 controls were included in the current meta-analysis.

RESULTS

The results suggested that the polymorphism rs2910164 was correlated with BD susceptibility in all genetic models. In subgroup analysis according to ethnicity, the relationship between this polymorphism and BD was more significant in Caucasians (allele model: OR = 0.49, 95% CI 0.39-0.61; heterozygote model: OR = 0.35, 95% CI 0.26-0.47; homozygote model: OR = 0.29, 95% CI 0.16-0.53; dominant model: OR = 0.34, 95% CI 0.25-0.45; recessive model: OR = 0.56, 95% CI 0.50-0.72) than that in Asians.

CONCLUSION

In conclusion, this meta-analysis indicates that miRNA-146a gene polymorphism rs2910164 G allele confers BD susceptibility, especially in Caucasians.

Transcriptome analysis of immune cells from Behçet's syndrome patients: the importance of IL-17-producing cells and antigen-presenting cells in the pathogenesis of Behçet's syndrome

Background

Behçet’s syndrome (BS) is an immune-mediated disease characterized by recurrent oral ulcers, genital ulcers, uveitis, and skin symptoms. HLA-B51, as well as other genetic polymorphisms, has been reported to be associated with BS; however, the pathogenesis of BS and its relationship to genetic risk factors still remain unclear. To address these points, we performed immunophenotyping and transcriptome analysis of immune cells from BS patients and healthy donors.

Methods

ImmuNexUT is a comprehensive database consisting of RNA sequencing data and eQTL database of immune cell subsets from patients with immune-mediated diseases and healthy donors, and flow cytometry data and transcriptome data from 23 BS patients and 28 healthy donors from the ImmuNexUT study were utilized for this study. Differential gene expression analysis and weighted gene co-expression network analysis (WGCNA) were performed to identify genes associated with BS and clinical features of BS. eQTL database was used to assess the relationship between genetic risk factors of BS with those genes.

Results

The frequency of Th17 cells was increased in BS patients, and transcriptome analysis of Th17 cells suggested the activation of the NFκB pathway in Th17 cells of BS patients. Next, WGCNA was used to group genes into modules with similar expression patterns in each subset. Modules of antigen-presenting cells were associated with BS, and pathway analysis suggested the activation of antigen-presenting cells of BS patients. Further examination of genes in BS-associated modules indicated that the expression of YBX3, a member of a plasmacytoid dendritic cell (pDC) gene module associated with BS, is influenced by a BS risk polymorphism, rs2617170, in pDCs, suggesting that YBX3 may be a key molecule connecting genetic risk factors of BS with disease pathogenesis. Furthermore, pathway analysis of modules associated with HLA-B51 indicated that the association of IL-17-associated pathways in memory CD8⁺ T cells with HLA-B51; therefore, IL-17-producing CD8⁺ T cells, Tc17 cells, may play a critical role in BS.

Conclusions

Various cells including CD4⁺ T cells, CD8⁺ T cells, and antigen-presenting cells are important in the pathogenesis of BS. Tc17 cells and YBX3 may be potential therapeutic targets in BS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02867-x.

Behçet's disease risk-variant HLA-B51/ERAP1-Hap10 alters human CD8 T cell immunity

OBJECTIVES

The endoplasmic reticulum aminopeptidase (ERAP1) haplotype Hap10 encodes for a variant allotype of the endoplasmic reticulum (ER)-resident peptide-trimming aminopeptidase ERAP1 with low enzymatic activity. This haplotype recessively confers the highest risk for Behçet's diseases (BD) currently known, but only in carriers of HLA-B*51, the classical risk factor for the disease. The mechanistic implications and biological consequences of this epistatic relationship are unknown. Here, we aimed to determine its biological relevance and functional impact.

METHODS

We genotyped and immune phenotyped a cohort of 26 untreated Turkish BD subjects and 22 healthy donors, generated CRISPR-Cas9 ERAP1 KOs from HLA-B*51 ⁺ LCL, analysed the HLA class I-bound peptidome for peptide length differences and assessed immunogenicity of genome-edited cells in CD8 T cell co-culture systems.

RESULTS

Allele frequencies of ERAP1-Hap10 were similar to previous studies. There were frequency shifts between antigen-experienced and naïve CD8 T cell populations of carriers and non-carriers of ERAP1-Hap10 in an HLA-B*51 background. ERAP1 KO cells showed peptidomes with longer peptides above 9mer and significant differences in their ability to stimulate alloreactive CD8 T cells compared with wild-type control cells.

CONCLUSIONS

We demonstrate that hypoactive ERAP1 changes immunogenicity to CD8 T cells, mediated by an HLA class I peptidome with undertrimmed peptides. Naïve/effector CD8 T cell shifts in affected carriers provide evidence of the biological relevance of ERAP1-Hap10/HLA-B*51 at the cellular level and point to an HLA-B51-restricted process. Our findings suggest that variant ERAP1-Hap10 partakes in BD pathogenesis by generating HLA-B51-restricted peptides, causing a change in immunodominance of the ensuing CD8 T cell response.

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.

Frenemies within: An Endocarditis Case in Behçet's Disease

A 57-year female patient diagnosed with Behçet's disease, on azathioprine, was noticed to have at a routine examination antinuclear and antiphospholipid antibodies. An overlapping lupus-like syndrome was diagnosed; hydroxychloroquine and aspirin were added. Three years later, the patient presented with dyspnea and sweating, with no fever. A cardiac bruit was noted; a giant vegetation was detected by echocardiography. Laboratory revealed severe thrombocytopenia, antiphospholipid antibodies and low complement. Blood cultures were positive for Abiotrophia defectiva serology and also revealed a chronic Coxiella burnetii infection. Antibiotic therapy, low-dose anticoagulation and control of the underlying disease mildly improved the platelet count, which fully recovered only after cardiac valve replacement. However, the Behçet's disease, initially quiescent, flared after the therapy of infections. We discuss potential links between Behçet's disease and the occurrence of antinuclear and antiphospholipid antibodies and Coxiella endocarditis in this setting. We also highlight the differences between the endocarditis in Behçet's disease, antiphospholipid syndrome, Coxiella burnetii and Abiotrophia defectiva infection, respectively. Intracellular infections may modify the presentation of autoimmune diseases. Confounding clinical features of Coxiella persistent infection and non-bacterial thrombotic endocarditis in Behçet's disease warrant further insight.

Behçet Disease: An Update for Dermatologists

Behçet disease (BD) is a chronic, relapsing, systemic vasculitis of unknown etiology with the clinical features of oral and genital ulcers, cutaneous vasculitic lesions, ocular, articular, vascular, gastrointestinal, neurologic, urogenital and cardiac involvement. BD usually appears around the third or fourth decade of life. Gender distribution is roughly equal. The disease is much more frequent in populations along the ancient 'Silk Road', extending from Eastern Asia to countries in the Middle East and the Mediterranean, compared with Western countries, but has universal distribution. Mucocutaneous manifestations are the clinical hallmarks of BD. The diagnostic criteria widely used in the disease's diagnosis are based on mucocutaneous manifestations because of their high sensitivity and/or specificity. Genetic factors are the key driver of BD pathogenesis, and HLA-B51 antigen is the strongest genetic susceptibility factor. Streptococcus sanguinis (S. sanguinis) or microbiome change can trigger innate immune system-mediated inflammation sustained by adaptive immune responses. Epistatic interaction between HLA-B51 and endoplasmic reticulum aminopeptidase 1 (ERAP1) in antigen-presenting cells disrupt T-cell homeostasis leading to downregulation of Tregs and expansion of Th1 and Th17. Thus, neutrophil activation and intense neutrophil infiltration of the affected organs develop in the early stage of inflammation. BD has a variable clinical course with unpredictable exacerbations and remissions. The disease is associated with a high mortality rate, especially in young male patients, and large-vessel, neurological, gastrointestinal system and cardiac involvement are the most important causes of death. The principal aim of treatment should be to prevent irreversible organ damage, especially during the disease's early, active phase. A better understanding of the disease's pathogenesis has provided important information on its management. New drugs, especially apremilast and anti-TNF-α agents are effective in the management of BD and have the potential to improve patients' quality of life, prognosis and survival.

Kinetics of Abacavir-Induced Remodelling of the Major Histocompatibility Complex Class I Peptide Repertoire

Abacavir hypersensitivity syndrome can occur in individuals expressing the HLA-B*57:01 major histocompatibility complex class I allotype when utilising the drug abacavir as a part of their anti-retroviral regimen. The drug is known to bind within the HLA-B*57:01 antigen binding cleft, leading to the selection of novel self-peptide ligands, thus provoking life-threatening immune responses. However, the sub-cellular location of abacavir binding and the mechanics of altered peptide selection are not well understood. Here, we probed the impact of abacavir on the assembly of HLA-B*57:01 peptide complexes. We show that whilst abacavir had minimal impact on the maturation or average stability of HLA-B*57:01 molecules, abacavir was able to differentially enhance the formation, selectively decrease the dissociation, and alter tapasin loading dependency of certain HLA-B*57:01-peptide complexes. Our data reveals a spectrum of abacavir mediated effects on the immunopeptidome which reconciles the heterogeneous functional T cell data reported in the literature.

Dose HLA-B5, 7, 8, 27, and 51 Antigens Associated to Behcet's disease? A Study in Southwestern Iran

BACKGROUND

Behcet's disease is a potentially life threatening autoimmune disease with recurrent ulcers and unknown pathogenesis. Gender and human leukocyte antigen-B51 seem to have an effective role in the clinical features of the disease.

OBJECTIVE

The aim of this study is to evaluate the frequency of HLA-B5, 7, 8, 27 and 51 in behçet's disease in southwestern Iranian patients who visited the rheumatology clinic and to find the association between these HLA types and the disease.

METHODS

63 patients with behcet's disease participated in this study and peripheral blood samples were collected from them. The expression of each HLA antigen was evaluated by standard lymphocytotoxicity technique.

RESULTS

Compared to other studied antigens, the expression of HLA-B5 and HLA-B51 was more prevalent among our patients. According to the results, 25% and 21% of patients were positive for HLA-B5 and HLA-B51, respectively.

CONCLUSIONS

HLA-B5 and HLA-B51 are dominant positive HLA antigens among behcet's disease patients in the southwest of Iran; however, we cannot conclude that these antigens are valuable diagnostic or prognostic biomarkers due to our study limitations. We suggest studying the association between HLA-B antigens and inflammation severity in patients to determine the possible prognostic value of HLA-B antigens in Iranian population in the southwest and this region needs more studies in HLA subject among BD patients because of the frequency of BD to evaluate the value of HLA typing in BD prognosis.

Experimental Therapeutic Solutions for Behcet's Disease

Behcet’s disease (BD) is a chronic systemic vasculitis with inflammation attacks that involve multiple organs. In addition to numerous mucocutaneous symptoms, notably recurrent oral and genital ulcers, ocular, articular, vascular, gastrointestinal, cardiac, and neurological system involvement can be observed. Mucocutaneous lesions are the primary symptom of the disease in most patients, and they usually occur before major organ involvement and other symptoms of the disease. Recognizing the disease’s mucocutaneous lesions is very important to diagnose at an early stage, control with appropriate treatment and close follow-up, and prevent major organ involvement. Genome-wide association studies (GWAS) in recent years have confirmed that HLA-B*51 is the most significant genetic predisposing factor. The majority of gene polymorphisms have been detected in molecules that respond to microorganisms and genes encoding cytokines and adhesion molecules. The infectious agent S. sanguinis -commonly found in the oral mucosa of patients with BD- or the differences in the salivary or intestinal microbiome composition can trigger innate immune-mediated inflammation sustained by acquired or adaptive immune responses. In antigen-presenting cells (APCs), epistatic interactions between HLA-B*51 and endoplasmic reticulum aminopeptidase 1 (ERAP1) variants lead to the disruption of T-cell homeostasis, especially the activation of Type1 T-helper and Th17 pathway and suppression of regulatory T-cells. Recent developments to clarify the disease’s etiopathogenesis provided us with a better understanding of the mechanism of action of the relatively old drugs while opening a way for many new treatment methods. Apremilast has become an important option in the treatment of mucocutaneous symptoms with its high efficacy and safety. The disease increases the mortality rate, especially in young male patients. New treatments, especially anti-TNF-α agents, have provided significant progress and decreased the mortality rates with their rapid effect and high efficacy in patients with severe organ involvement and resistance to traditional immunosuppressive and immunomodulatory therapies. The use of IL-1, IL-6, IL-17, IL-12/IL-23 antagonists in different organ involvement has gradually increased, and the quality of life has significantly improved in many patients.

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.

Mimicking Behçet's disease: GM-CSF gain of function mutation in a family suffering from a Behçet's disease-like disorder marked by extreme pathergy

Behçet's disease (BD) is an inflammatory disease mainly affecting men along the ancient Silk Route. In the present study we describe a Dutch family suffering from BD-like disease with extreme pathergic responses, but without systemic inflammation. Genetic assessment revealed a combination of the human leukocyte antigen (HLA)-B*51 risk-allele together with a rare heterozygous variant in the CSF2 gene (c.130A>C, p.N44H) encoding for granulocyte-macrophage colony-stimulating factor (GM-CSF) found by whole exome sequencing. We utilized an over-expression vector system in a human hepatocyte cell line to produce the aberrant variant of GM-CSF. Biological activity of the protein was measured by signal transducer and activator of transcription 5 (STAT-5) phosphorylation, a downstream molecule of the GM-CSF receptor, in wild-type peripheral mononuclear cells (PBMCs) using flow cytometry. Increased STAT-5 phosphorylation was observed in response to mutated GM-CSF when compared to the wild-type or recombinant protein. CSF2 p.N44H results in disruption of one of the protein's two N-glycosylation sites. Enzymatically deglycosylated wild-type GM-CSF also enhanced STAT-5 phosphorylation. The patient responded well to anti-tumor necrosis factor (TNF)-α treatment, which may be linked to the capacity of TNF-α to induce GM-CSF in phorbol 12-myristate 13-acetate (PMA)-treated PBMCs, while GM-CSF itself only induced dose-dependent interleukin (IL)-1Ra production. The identified CSF2 pathway could provide novel insights into the pathergic response of BD-like disease and offer new opportunities for personalized treatment.

The Impact of the 'Mis-Peptidome' on HLA Class I-Mediated Diseases: Contribution of ERAP1 and ERAP2 and Effects on the Immune Response

The strong association with the Major Histocompatibility Complex (MHC) class I genes represents a shared trait for a group of autoimmune/autoinflammatory disorders having in common immunopathogenetic basis as well as clinical features. Accordingly, the main risk factors for Ankylosing Spondylitis (AS), prototype of the Spondyloarthropathies (SpA), the Behçet's disease (BD), the Psoriasis (Ps) and the Birdshot Chorioretinopathy (BSCR) are HLA-B*27, HLA-B*51, HLA-C*06:02 and HLA-A*29:02, respectively. Despite the strength of the association, the HLA pathogenetic role in these diseases is far from being thoroughly understood. Furthermore, Genome-Wide Association Studies (GWAS) have highlighted other important susceptibility factors such as Endoplasmic Reticulum Aminopeptidase (ERAP) 1 and, less frequently, ERAP2 that refine the peptidome presented by HLA class I molecules to CD8⁺ T cells. Mass spectrometry analysis provided considerable knowledge of HLA-B*27, HLA-B*51, HLA-C*06:02 and HLA-A*29:02 immunopeptidome. However, the combined effect of several ERAP1 and ERAP2 allelic variants could generate an altered pool of peptides accounting for the "mis-immunopeptidome" that ranges from suboptimal to pathogenetic/harmful peptides able to induce non-canonical or autoreactive CD8⁺ T responses, activation of NK cells and/or garbling the classical functions of the HLA class I molecules. This review will focus on this class of epitopes as possible elicitors of atypical/harmful immune responses which can contribute to the pathogenesis of chronic inflammatory diseases.

Initial whole-genome sequencing and analysis of the host genetic contribution to COVID-19 severity and susceptibility

The COVID-19 pandemic has accounted for millions of infections and hundreds of thousand deaths worldwide in a short-time period. The patients demonstrate a great diversity in clinical and laboratory manifestations and disease severity. Nonetheless, little is known about the host genetic contribution to the observed interindividual phenotypic variability. Here, we report the first host genetic study in the Chinese population by deeply sequencing and analyzing 332 COVID-19 patients categorized by varying levels of severity from the Shenzhen Third People's Hospital. Upon a total of 22.2 million genetic variants, we conducted both single-variant and gene-based association tests among five severity groups including asymptomatic, mild, moderate, severe, and critical ill patients after the correction of potential confounding factors. Pedigree analysis suggested a potential monogenic effect of loss of function variants in GOLGA3 and DPP7 for critically ill and asymptomatic disease demonstration. Genome-wide association study suggests the most significant gene locus associated with severity were located in TMEM189-UBE2V1 that involved in the IL-1 signaling pathway. The p.Val197Met missense variant that affects the stability of the TMPRSS2 protein displays a decreasing allele frequency among the severe patients compared to the mild and the general population. We identified that the HLA-A*11:01, B*51:01, and C*14:02 alleles significantly predispose the worst outcome of the patients. This initial genomic study of Chinese patients provides genetic insights into the phenotypic difference among the COVID-19 patient groups and highlighted genes and variants that may help guide targeted efforts in containing the outbreak. Limitations and advantages of the study were also reviewed to guide future international efforts on elucidating the genetic architecture of host-pathogen interaction for COVID-19 and other infectious and complex diseases.

Succinivibrionaceae is dominant family in fecal microbiota of Behçet's Syndrome patients with uveitis

Behçet’s Syndrome (BS) is a multisystem vasculitis with various clinical manifestations. Pathogenesis is unclear, but studies have shown genetic factors, innate immunity and autoinflammation to have an important role in the disease course. Diversity in the microbial community of gut microbiota may significantly contribute to the activation of the innate immune system. The clinical features of BS present themselves in clusters and each cluster may be a consequence of different disease mechanisms. For this reason we aimed to investigate the gut microbiota of BS patients with uveitis. In addition to healthy controls, we have aimed to compare the gut microbiota of BS with that of Familial Mediterranean Fever (FMF) and Crohn’s Disease (CD) as both diseases have innate and autoinflammatory features in their pathogenesis. Seven patients with BS, 12 patients with FMF, 9 patients with CD and 16 healthy controls (HC) were included in the study. Total genomic DNAs were isolated from fecal samples of the patients. Partial 16S rRNA gene was sequenced using the PGM Ion Torrent (Thermo Fisher Scientific, Waltham, MA, USA) for microbiota analysis. Statistical analysis showed that significant differences were detected on the microbial community of four groups. Succinivibrionaceae is dominant and the signature family, whereas Bacteroides was absent in BS patients.

Behçet's syndrome in Italy: a detailed retrospective analysis of 396 cases seen in 3 tertiary referral clinics

Behçet's syndrome (BS) is a multisystemic disorder displaying a marked variability across different geographic areas. The main aim of this study was to analyze demographic and clinical features of a cohort of BS patients diagnosed in three tertiary referral centers in Italy and detect potential associations between the different manifestations. Medical records of 396 patients (218 females, 178 males) were retrospectively analyzed. Mean age at onset was 30.00 ± 18.75 years with a female-to-male ratio of 1.22:1. Mucocutaneous features were the most frequent starting manifestations of BS, followed by eye inflammation. Erythema nodosum (p = 0.007), arthritis/arthralgias (p = 0.0115), and central nervous system (CNS) signs (p = 0.014) were significantly over-represented in female patients, whereas male gender was associated with lower mean age at onset (p = 0.031), higher frequency of pseudofollicular lesions, and uveitis (p = 0.00134 and p < 0.0001 respectively), particularly for posterior segment involvement and panuveitis (p < 0.0001). Regarding the association between disease features, genital ulcers were negatively associated with uveitis (p < 0.0001) and vascular involvement (p < 0.0001). Other negative associations were detected between uveitis and gastrointestinal involvement (p = 0.008), pseudofolliculitis and CNS signs (p = 0.031), vascular involvement (p = 0.002) and erythema nodosum (p = 0.013). Logistic regression identified male gender and genital ulcers, respectively, with a higher (OR 2.199 [1.397-3.461], p < 0.001) and lower risk (OR 0.157 [0.090-0.273], p < 0.0001) of developing major organ involvement. Our evaluations found that the disease had started mostly in the second and third decade with most severe features in the male gender, and that patients presenting with mucocutaneous manifestations were less prone to develop major organ involvement.

Psoriasis and Connective Tissue Diseases

Psoriasis is a chronic systemic inflammatory disease with various co-morbidities, having been recently considered as a comprehensive disease named psoriatic disease or psoriatic syndrome. Autoimmune diseases are one form of its co-morbidities. In addition to the genetic background, shared pathogenesis including innate immunity, neutrophil extracellular trap (NETs), and type I interferon, as well as acquitted immunity such as T helper-17 (Th17) related cytokines are speculated to play a significant role in both psoriasis and connective tissue diseases. On the other hand, there are definite differences between psoriasis and connective tissue diseases, such as their pathomechanisms and response to drugs. Therefore, we cannot expect that one stone kills two birds, and thus caution is necessary when considering whether the administered drug for one disease is effective or not for another disease. In this review, several connective tissue diseases and related diseases are discussed from the viewpoint of their coexistence with psoriasis.

Behçet's Disease in Children: Diagnostic and Management Challenges

Behçet’s Disease (BD) is an inflammatory disease of unknown etiology with multisystemic involvement, being the main clinical manifestations represented by recurrent oral and genital ulcerations and uveitis. The disease has typically a chronic-relapsing course and may cause significant morbidity and mortality due to eye, vascular and neurological involvement. Although BD is more frequently diagnosed in adulthood, the disease onset can also be in pediatric age. Pediatric-onset BD is commonly featured by an incomplete clinical picture, and therefore the diagnosis represents a considerable clinical challenge for the physicians. The first classification criteria for pediatric BD, based on a scoring system, have been proposed few years ago. This work focuses on the main difficulties concerning both the diagnostic approach and the treatment of BD in pediatric age. The recommendation for the treatment of pediatric BD has been recently updated and allowed a considerable improvement of the therapeutic strategies. In particular, the use of anti-TNFα drugs as a second-line option for refractory BD, and as a first-line treatment in severe ocular and neurological involvement, has demonstrated to be effective in improving the outcome of BD patients. The knowledge about the molecular pathogenesis is progressively increasing, showing that BD shares common features with autoimmune and autoinflammatory disorders, and thus leading to the use of new biologic agents targeting the main mediators involved in the determination of BD. Anti-IL-17, anti-IL-23, anti-IL-1 and anti-IL-6 agents have shown promising results for the treatment of refractory BD in clinical trials and will represent an important alternative for the therapeutic approach to the disease.

Cancer incidence in Behçet's disease

BACKGROUND

Previous studies demonstrated an increased cancer risk in autoimmune diseases. Behçet's disease (BD) was also reported to be associated with an increased risk of cancer, although the data is limited.

AIMS

In this study, we aimed to assess cancer incidence in a large cohort of BD patients and to compare with the data of the same age and gender groups.

METHODS

The study cohort consisted of BD patients of > 18 years of age who were prospectively recorded in the Hacettepe University Vasculitis Center. Data on any cancer was collected from the patient files. Cancer incidence was compared with age- and gender-specific cancer incidence rates of the normal population retrieved from the 2014 Turkish National Cancer Registry (TNCR) data using standardized incidence rates (SIR).

RESULTS

Totally, 451 adult cases with BD were included. The median age of the cohort was 43 (20-75), and 52.5% of the patients were males. Eleven cancer cases were observed during a median of 124 months follow-up. Behçet's disease was associated with an increase in cancer risk compared with expected counts in the corresponding age and sex group (SIR 2.84, 95% CI 1.50-4.94, p < 0.001). Patients with papulopustular lesions had a trend toward a decreased risk of cancer (p = 0.060), and patients using azathioprine had a significantly decreased cancer risk (p = 0.031).

CONCLUSION

This study revealed BD patients had approximately three times increased cancer risk compared with corresponding age and sex groups. Besides the routine care, increased attention for cancer surveillance is required in the follow-up of BD patients.

Long-term effectiveness and safety of secukinumab for treatment of refractory mucosal and articular Behçet's phenotype: a multicentre study

OBJECTIVE

To evaluate the effectiveness and safety of secukinumab in patients with a mucosal and articular Behçet's phenotype resistant to conventional and biologic treatment.

METHODS

A multicentre retrospective study was performed on 15 patients with a mucosal and articular phenotype of Behçet's syndrome fulfilling the International Criteria for Behçet's Disease and refractory to treatment with colchicine, disease-modifying antirheumatic drugs and at least one antitumour necrosis factor-α agent. Minimum follow-up was set at 6 months. Six patients with a polyarticular involvement were treated with secukinumab 300 mg/month, while all other cases received secukinumab 150 mg/month. Dose increase from 150 to 300 mg per month and shortening of administration frequency were allowed for poor disease control. Response evaluation was based on the number of oral ulcers in the previous 28 days and Disease Activity Score-28 for articular manifestations.

RESULTS

At 3 months of follow-up, nine (66.7%) patients achieved a response (complete or partial), and this proportion further increased to 86.7% at 6 months, 76.9% at 12 months, 90.0% at 18 months and 100.0% after 24 months. Notably, all patients who started with secukinumab 300 mg/month achieved complete response by month 6. Seven (46.7%) patients could achieve a response only after switching to a higher dosage.

CONCLUSIONS

Our study suggests that secukinumab at a dose of 150 and 300 mg per month is safe and effective for the long-term treatment of patients with Behçet's syndrome with a mucosal and articular phenotype refractory to previous treatments. Notably, secukinumab 300 mg/month resulted in superior complete mucosal and articular responses with no serious or dose-related adverse effects.

Identification of an Unconventional Subpeptidome Bound to the Behçet's Disease-associated HLA-B*51:01 that is Regulated by Endoplasmic Reticulum Aminopeptidase 1 (ERAP1)

Human leukocyte antigen (HLA) B*51:01 and endoplasmic reticulum aminopeptidase 1 (ERAP1) are strongly genetically associated with Behçet's disease (BD). Previous studies have defined two subgroups of HLA-B*51 peptidome containing proline (Pro) or alanine (Ala) at position 2 (P2). Little is known about the unconventional non-Pro/Ala2 HLA-B*51-bound peptides. We aimed to study the features of this novel subpeptidome, and investigate its regulation by ERAP1. CRISPR-Cas9 was used to generate an HLA-ABC-triple knockout HeLa cell line (HeLa.ABC-KO), which was subsequently transduced to express HLA-B*51:01 (HeLa.ABC-KO.B51). ERAP1 was silenced using lentiviral shRNA. Peptides bound to HLA-B*51:01 were eluted and analyzed by mass spectrometry. The characteristics of non-Pro/Ala2, Pro2, and Ala2 peptides and their alteration by ERAP1 silencing were investigated. Effects of ERAP1 silencing on cell surface expression of HLA-B*51:01 were studied using flow cytometry. More than 20% of peptides eluted from HLA-B*51:01 lacked Pro or Ala at P2. This unconventional group of HLA-B*51:01-bound peptides was relatively enriched for 8-mers (with relatively fewer 9-mers) compared with the Pro2 and Ala2 subpeptidomes and had similar N-terminal and C-terminal residue usages to Ala2 peptides (with the exception of the less abundant leucine at position Ω). Knockdown of ERAP1 increased the percentage of non-Pro/Ala2 from 20% to ∼40%, increased the percentage of longer (10-mer and 11-mer) peptides eluted from HLA-B*51:01 complexes, and abrogated the predominance of leucine at P1. Interestingly knockdown of ERAP1 altered the length and N-terminal residue usage of non-Ala2&Pro2 and Ala2 but not the Pro2 peptides. Finally, ERAP1 silencing regulated the expression levels of cell surface HLA-B*51 in a cell-type-dependent manner. In conclusion, we have used a novel methodology to identify an unconventional but surprisingly abundant non-Pro/Ala2 HLA-B*51:01 subpeptidome. It is increased by knockdown of ERAP1, a gene affecting the risk of developing BD. This has implications for theories of disease pathogenesis.

Treating the Different Phenotypes of Behçet's Syndrome

Behçet's syndrome (BS) is a multisystemic vasculitis, characterized by different clinical involvements, including mucocutaneous, ocular, vascular, neurological, and gastrointestinal manifestations. Based on this heterogeneity, BS can be hardly considered as a single clinical entity. Growing evidence supports that, within BS, different phenotypes, characterized by clusters of co-existing involvements, can be distinguished. Namely, three major BS phenotypes have been reported: (a) the mucocutaneous and articular phenotype, (b) the extra-parenchymal neurological and peripheral vascular phenotype, and (c) the parenchymal neurological and ocular phenotype. To date, guidelines for the management of BS have been focused on the pharmacological treatment of each specific BS manifestation. However, tailoring the treatments on patient's specific phenotype, rather than on single disease manifestation, could represent a valid strategy for a personalized therapeutic approach to BS. In the present literature review, we summarize current evidence on the pharmacological treatments for the first-, second-, and third-line treatment of the major BS phenotypes.

Clinical features and disease course of neurological involvement in Behcet's disease: HUVAC experience

BACKGROUND/AIM

Neurological involvement (Neuro-Behcet's Disease: NBD) is a rare manifestation of Behcet's Disease (BD) and it is related with significant mortality and morbidity. We aimed to evaluate disease course and outcome of NBD patients registered in Hacettepe University Vasculitis Center (HUVAC) prospective database starting from October 2014.

METHODS

Totally, 419 patients (329 of the patients had fulfilled the International Study Group (ISG) criteria and 90 patients were considered as incomplete BD) were recorded as BD to March 2018. We retrospectively reviewed the charts of 123 patients with neurological complaints/ symptoms according International Consensus Recommendations (ICR) Criteria for Neuro-Behçet's disease. In final analysis, 77 NBD patients (Definite NBD = 61, possible NBD = 16) were included. Demographics, clinical features, treatment characteristics, disability status and survival status of the patients were evaluated.

RESULTS

Forty-seven (61%) of the patients were male. Median time to neurological involvement from first diagnosis of BD is 6 (IQR = 8.8) years in patients who had diagnosis of BD before neurological involvement. Distribution of NBD: parenchymal (pNBD), non-parenchymal (npNBD), mixed (mNBD) and peripheral nervous system (pnsNBD) were 47 (61%), 22 (28.6%), 5 (6.5%), 3 (3.9%), respectively. Eye involvement was more frequent in pNBD compared to npNBD. Brainstem (72.9%) was the most frequently affected parenchymal area and followed by cerebellum (43.8%) and diencephalon (37.5%). Twelve patients had spinal cord involvement (n = 12, 24.5%). Among the patients with pNBD and mNBD (total n = 52), 48 patients were considered as acute onset parenchymal disease and 4 patients were evaluated as chronic progressive disease. Fifty-eight percent of the patients with acute onset parenchymal disease had only one attack. Totally 14 BD patients deceased during a median 9.4 (IQR = 13) years disease duration and 9 of these patients had NBD (pNBD = 6, mNBD = 2, pnsNBD = 1). Corticosteroids (IV pulse = 75.5% and oral medium-high dose = 90%), alpha-interferon (76.9%), cyclophosphamide (57.1%), and TNF inhibitors (23.5%) were the most frequently preferred treatment options for pNBD.

CONCLUSIONS

Neurological involvement is seen about 5 years after the diagnosis of BD, and ocular involvement more commonly seen in these patients than non-NBD patients. More than half of the patients with acute onset parenchymal NBD had only one attack. No death was observed in the patients with non-parenchymal NBD. Biologic agents (Interferon-alpha and anti-TNF agents) were used in most patients.

MEFV gene mutations in neuro-Behçet's disease and neuro-Sweet disease

Mediterranean fever (MEFV) gene mutations are associated with familial Mediterranean fever (FMF). Recent studies have suggested that MEFV gene mutations may act as disease modifiers in neuro‐Behçet's (NBD) disease and neuro‐Sweet disease (NSD). We investigated MEFV genes and clinical features in 17 patients with NBD or NSD. MEFV gene mutations were frequently observed (70.6%). Headaches and exertional leg pain were associated with MEFV gene mutations (P < 0.05). Moreover, higher frequency of white matter lesions without sites predilection (P < 0.05) and non‐parenchymal lesions (P < 0.05) were also observed. MEFV gene mutations may be associated with particular findings and lesion sites.

TIM-3 genetic variants and risk of Behçet disease in the Iranian population

BACKGROUND

Behçet disease is a prototypical systemic autoimmune disease, caused by a complex interplay between environmental and genetic factors. The transmembrane immunoglobulin and mucin domain-3 (TIM-3) is a distinct member of the TIM family that is preferentially expressed on Th1 cells and plays a role in Th1-mediated autoimmune or inflammatory diseases, such as Behçet disease.

OBJECTIVE

The aim of this study was to test the potential association between TIM-3 gene polymorphisms and Behçet disease.

METHODS

Two single-nucleotide polymorphisms of TIM-3 (rs9313439 and rs10515746) were genotyped in 212 patients with Behçet disease and 200 healthy controls. Typing of the polymorphisms was performed using multiplex PCR amplification.

RESULTS

There were no significant differences in allele and genotype frequencies between the Behçet disease patients and controls who were successfully genotyped. Similar results were also found after stratification by gender, age, or clinical features.

STUDY LIMITATIONS

Lack of studies on various racial or ethnic groups and small sample size.

CONCLUSION

This study failed to demonstrate any association between the tested TIM-3 polymorphisms and Behçet disease.

Behçet's Disease: An Overview of Etiopathogenesis

Behçet's disease (BD) is a systemic inflammatory disease with a chronic, relapsing-remitting course of unknown etiology hallmarked predominantly by mucocutaneous lesions and ocular involvement. BD shares some common features with autoimmune and autoinflammatory diseases and spondyloarthropathies (MHC-I-opathies). It is related to more than one pathogenic pathway triggered by environmental factors such as infectious agents in genetically predisposed subjects. The interplay between genetic background and immune system is linked to the BD presentation. Genetic factors have been investigated extensively, and several recent genome-wide association studies have confirmed HLA-B ^* 51 to be the strongest genetic susceptibility factor. However, new non-HLA susceptibility genes have been identified. Genetic variations in the genes encoding the cytokines could affect their function and be associated with disease susceptibility. Infectious agents such as Streptococcus sanguinis or the differences in salivary or gut microbiome composition can be considered to trigger the innate-derived inflammation, which is, subsequently, sustained by adaptive immune responses. Altered trimming of microbial and/or endogenous peptides by endoplasmic reticulum aminopeptidase 1 (ERAP1), presented by HLA-B ^* 51, may play a key role in BD pathogenesis causing an alteration in T cell balance with downregulation of Tregs and expansion of Th1 and Th17. The activity of neutrophils is increased and there is an intense neutrophil infiltration in the early stage of inflammation in organs affected by the disease. Association with HLA-B ^* 51 and increased IL-17 response seems to have an important role in neutrophil activity. In this paper, we provide an overview of the most recent advances on BD etiopathogenesis.

Human Leukocyte Antigens (HLA) Genes Association in Type 1 Diabetic Nephropathy

BACKGROUND

Diabetic nephropathy is a common worldwide multifactorial disease where involvement of genetic factors is well etablished. The aim of this study was to investigate the HLA genes implication in the development of type 1 diabetic nephropathy.

METHODS

We performed a case- control study where one hundred and fifty subjects were examined. Patients were divided in two groups; with and without type 1 diabetic nephropathy. HLA typing was performed using Polymerase Chain Reaction- Sequence Specific Oligonucleotide (PCR- SSO) method. HLA association to clinical phenotype and HLA haplotype analysis was also investigated.

RESULTS

HLA B*51 is increased in patients without type 1 diabetic nephropathy (7.14% vs. 0 %, P <0.05, OR= 0), however no other studied alleles seem to have any effect (all P>0.05). Haplotype analysis also does not reveal any significant association, however, A*02-B*18-DRB1*03-DQA1*05- DQB1*03 haplotype shows a tendency to be associated with the development of diabetic nephropathy (P = 0.05).

CONCLUSION

These results suggest a protective effect of HLA B*51 allele from type 1 diabetic nephropathy. However, further studies are required in order to clarify its potential implication as a protective marker.

Functionally distinct ERAP1 and ERAP2 are a hallmark of HLA-A29-(Birdshot) Uveitis

Birdshot Uveitis (Birdshot) is a rare eye condition that affects HLA-A29-positive individuals and could be considered a prototypic member of the recently proposed 'MHC-I (major histocompatibility complex class I)-opathy' family. Genetic studies have pinpointed the endoplasmic reticulum aminopeptidase (ERAP1) and (ERAP2) genes as shared associations across MHC-I-opathies, which suggests ERAP dysfunction may be a root cause for MHC-I-opathies. We mapped the ERAP1 and ERAP2 haplotypes in 84 Dutch cases and 890 controls. We identified association at variant rs10044354, which mediated a marked increase in ERAP2 expression. We also identified and cloned an independently associated ERAP1 haplotype (tagged by rs2287987) present in more than half of the cases; this ERAP1 haplotype is also the primary risk and protective haplotype for other MHC-I-opathies. We show that the risk ERAP1 haplotype conferred significantly altered expression of ERAP1 isoforms in transcriptomic data (n = 360), resulting in lowered protein expression and distinct enzymatic activity. Both the association for rs10044354 (meta-analysis: odds ratio (OR) [95% CI]=2.07[1.58-2.71], P = 1.24 × 10(-7)) and rs2287987 (OR[95% CI]: =2.01[1.51-2.67], P = 1.41 × 10(-6)) replicated and showed consistent direction of effect in an independent Spanish cohort of 46 cases and 2103 controls. In both cohorts, the combined rs2287987-rs10044354 haplotype associated with Birdshot more strongly than either variant alone [meta-analysis: P=3.9 × 10(-9)]. Finally, we observed that ERAP2 protein expression is dependent on the ERAP1 background across three European populations (n = 3353). In conclusion, a functionally distinct combination of ERAP1 and ERAP2 are a hallmark of Birdshot and provide rationale for strategies designed to correct ERAP function for treatment of Birdshot and MHC-I-opathies more broadly.

Immune Regulatory Genes Are Major Genetic Factors to Behcet Disease: Systematic Review

Behcet's disease (BD) is a chronic refractory multi-system autoimmune disorder that occurs in a genetically susceptible host. Multiple genetic factors have been identified that may contribute to the pathogenesis of BD. The major genes with polymorphisms associated with BD include HLA-B and -A, CIITA, ERAP1, MICA, IL10, IL12A, IL12RB2, IL23R, MEFV, IRF8, TNFAIP3, REL, TLR4, NOD1,2, CCR1,CCR3, GIMAP1,2,4, KLRC4, STAT4, NCOA5, FOXP3, PSORS1C1, FUT2, UBAC2, SUMO4, ADO-EGR2, CEBPB-PTPN1, and JPKL-CNTN5. These genes encode proteins involved mainly in immune regulation and inflammation, and some in transcription and post-translational modification. A complete view of these BD-associated genes may provide a clue to this complex disease in terms of its pathogenesis and exploring potentially targeted therapies for BD.