HLA-B*51 and Behçet Disease

Juvenile Behçet syndrome: a contemporary view and differential diagnosis in pediatric practice

PURPOSE OF REVIEW

This review aims to provide a comprehensive and contemporary overview of juvenile Behçet syndrome (jBS), highlighting its clinical manifestations, diagnostic challenges, and treatment strategies.

RECENT FINDINGS

Behçet syndrome, with its intricate etiopathogenesis and diverse clinical phenotypes, is more aptly classified as a syndrome than a single disease. Its heterogeneous nature requires a broad diagnostic approach and sophisticated differential diagnosis capabilities. The relatively rare occurrence of Behçet syndrome, combined with incomplete clinical presentations and overlapping differential diagnoses, presents significant diagnostic challenges, particularly in pediatric cases. Nevertheless, substantial progress has been made in treatment, especially in managing inflammatory components and preventing complications. Juvenile patients, given their developmental stage, require distinct therapeutic strategies compared to adults, with careful consideration of treatment side effects on growth and psychosocial development.

SUMMARY

To ensure early identification of jBS, it is imperative to refine and develop diagnostic criteria specifically tailored to pediatric populations. With a deeper understanding of the disease mechanisms, treatment protocols should be designed to address the developmental, psychosocial, and individual needs of patients, aiming to minimize long-term side effects. Additionally, comprehensive studies considering age, sex, and ethnic differences are necessary to fill gaps in the literature and resolve existing inconsistencies.

HLA-B*51:01 in Iranian patients with Behcet uveitis syndrome

BACKGROUND

Behcet's disease (BD) is a multisystem disorder prevalent along the historic Silk Road, with Behcet's uveitis (BU) representing a significant complication contributing to disability. Various studies have linked different HLA alleles with BD across diverse populations.

METHODS

In this study, we investigated the association between HLA-B51:01/x and HLA-B27/x genotypes with Behcet's uveitis in 50 unrelated Iranian patients diagnosed with Behcet's uveitis, comparing them to a control group of 70 healthy individuals. Our analysis aimed to determine the susceptibility conferred by these alleles and assess their clinical relevance.

RESULTS

Our findings indicate a notable susceptibility conferred by the HLA-B51:01/x genotype for Behcet's uveitis (P=0.0001). Conversely, the B27/x genotype did not demonstrate significant associations with Behcet's uveitis. Furthermore, we employed prevalence-corrected positive predictive value (PcPPV) calculations to gauge the clinical utility of testing for these alleles within the Iranian Behcet's uveitis patient population. The PcPPV for B27/x genotype testing was determined to be 0.05%, while the PcPPV for B51:01/x genotype testing in the same population was 0.065%. These results suggest that carriers of the B*51:01 allele, when presenting with clinical symptoms, exhibit a heightened risk for Behcet's uveitis compared to the general population.

CONCLUSION

Individuals carrying the B51:01 allele, when symptomatic, face an elevated Behcet's uveitis risk. This insight aids in targeted clinical assessments for at-risk populations.

Behçet's Syndrome in a Child: A Case Report and a Review of Literature

Behçet's syndrome is a complex chronic inflammatory disorder characterized by widespread inflammation of the blood vessels, affecting various systems in the body. Although its exact cause remains unknown, genetic predisposition, particularly HLA-B51/B5 gene carriage, and environmental factors are believed to play roles. The disease typically manifests in individuals aged 20-40 years, with an uncommon occurrence in children and elderly individuals. Key clinical manifestations include recurrent oral and genital ulcers, skin lesions, ocular involvement, positive pathergy test results, and other systemic symptoms. Eye involvement is common and can lead to severe visual impairment if left untreated. This diversity of Behçet's disease (BD) presentations and complications emphasizes the importance of early recognition and management. An eight-year-old girl presented with a deep painful ulcer in the mouth and a history of chronic constipation, severe joint pain, and recurrent mouth ulcers. Initial examination revealed an ulcer scar on the tongue and a deep ulcer on the left side of the mucobuccal fold. The patient was diagnosed with a recurrent major aphthous ulcer and prescribed Predo pediatric syrup as a mouthwash and paracetamol to relieve the pain. A biopsy was recommended by her physician to be done under general anesthesia and to rule out malignancy; the biopsy result revealed the presence of a benign squamous epithelium with reactive changes. The genetic result revealed HLA B*51 positivity and normal immunoglobulin levels. Treatment with colchicine led to the complete healing of the ulcer with scar formation after three months. This case report highlights the unique presentation of Behçet's syndrome in children and the challenges associated with its diagnosis. It emphasizes the importance of the early recognition and prompt management of BD in the pediatric population, in which disease progression can be more severe than in adult-onset cases. This case provides valuable insights into the clinical features of and diagnostic approach to Behçet's syndrome in children.

Application of mendelian randomization in ocular diseases: a review

Ocular disorders can significantly lower patients' quality of life and impose an economic burden on families and society. However, for the majority of these diseases, their prevalence and mechanisms are yet unknown, making prevention, management, and therapy challenging. Although connections between exposure factors and diseases can be drawn through observational research, it is challenging to rule out the interference of confounding variables and reverse causation. Mendelian Randomization (MR), a method of research that combines genetics and epidemiology, has its advantage to solve this problem and thus has been extensively utilized in the etiological study of ophthalmic diseases. This paper reviews the implementation of MR in the research of ocular diseases and provides approaches for the investigation of related mechanisms as well as the intervention strategies.

Biology of HLA class I associated inflammatory diseases

Human leukocyte antigen (HLA) class I association is a well-established feature of common and uncommon inflammatory diseases, but it is unknown whether it impacts the pathogenesis of these disorders. The "arthritogenic peptide" hypothesis proposed initially for HLA-B27-associated ankylosing spondylitis (AS) seems the most intuitive to serve as a model for other HLA class I-associated diseases, but evidence supporting it has been scarce. Recent technological advances and the discovery of epistatic relationships between disease-associated HLA class I and endoplasmic reticulum aminopeptidase (ERAP) coding variants have led to the generation of new data and conceptual approaches to the problem requiring its re-examination. Continued success in these endeavors holds promise to resolve a Gordian Knot in human immunobiology. It may ultimately benefit patients by enabling the development of new therapies and precision tools for assessing disease risk and predicting treatment responses.

[Behçet's and Cogan's syndromes - The Variable Vessel Vasculitides]

Behçet's syndrome and Cogan's syndrome constitute the group of variable vessel vasculitides in the Chapel-Hill Nomenclature. They involve arteries and veins of all sizes. As reflected in the name "syndrome", both diseases can manifest with different individual symptoms. Both formally are rare diseases, but the Cogan syndrome is much rarer than Behçet`s. For the latter, there are diagnosis and classification criteria as well as European (EULAR, European Alliance of Associations for Rheumatology) treatment recommendations. The symptomatology, diagnostic measures and treatment as well as some considerations about pathogenesis will be discussed in this article.

CXCL13 in Cerebrospinal Fluid: Clinical Value in a Large Cross-Sectional Study

C-X-C-motif chemokine ligand 13 (CXCL13) in cerebrospinal fluid (CSF) is increasingly used in clinical routines, although its diagnostic specificity and divergent cut-off values have been defined so far mainly for neuroborreliosis. Our aim was to evaluate the value of CSF-CXCL13 as a diagnostic and treatment response marker and its role as an activity marker in a larger disease spectrum, including neuroborreliosis and other neuroinflammatory and malignant CNS-disorders. Patients who received a diagnostic lumbar puncture (LP) (n = 1234) between July 2009 and January 2023 were included in our retrospective cross-sectional study. The diagnostic performance of CSF-CXCL13 for acute neuroborreliosis was highest at a cut-off of 428.92 pg/mL (sensitivity: 92.1%; specificity: 96.5%). In addition, CXCL13 levels in CSF were significantly elevated in multiple sclerosis with clinical (p = 0.001) and radiographic disease activity (p < 0.001). The clinical utility of CSF-CXCL13 appears to be multifaceted. CSF-CXCL13 is significantly elevated in patients with neuroborreliosis and shows a rapid and sharp decline with antibiotic therapy, but it is not specific for this disease and is also highly elevated in less common subacute neuroinfectious diseases, such as neurosyphilis and cryptococcal meningitis or in primary/secondary B-cell lymphoma.

Autoimmune Heart Disease: A Comprehensive Summary for Forensic Practice

Autoimmune heart disease is a non-random condition characterised by immune system-mediated aggression against cardiac tissue. Cardiac changes often exhibit nonspecific features and, if unrecognised, can result in fatal outcomes even among seemingly healthy young individuals. In the absence of reliable medical history, the primary challenge lies in differentiating between the various cardiopathies. Numerous immunohistochemical and genetic studies have endeavoured to characterise distinct types of cardiopathies, facilitating their differentiation during autopsy examinations. However, the presence of a standardised protocol that forensic pathologists can employ to guide their investigations would be beneficial. Hence, this summary aims to present the spectrum of autoimmune cardiopathies, including emerging insights such as SARS-CoV-2-induced cardiopathies, and proposes the utilisation of practical tools, such as blood markers, to aid forensic pathologists in their routine practice.

Lesion probability map in cerebral vein thrombosis due to Behçet's disease

AIM

Behçet's disease (BD) is a multisystemic inflammatory disease. Cerebral venous sinus thrombosis (CVST) is the second most common form of neuro-BD after parenchymal central nervous system involvement. The purpose of this study was to construct flow-void probability maps of patients with CVST with and without BD to visually illustrate the impacted cerebral venous sinuses, to compare the subgroups of patients, and investigate the effect of thrombus localization on clinical findings.

METHODS

Seventeen patients with a diagnosis of BD-related CVST (CVST-BD) and 23 patients with a diagnosis of CVST related to other etiologies (CVST-O) were included. We collected data including gender, age at onset of BD and CVST, presenting symptoms, neurological findings, and the etiology. High-resolution magnetic resonance venographies obtained during CVST were used to mark and digitalize thrombosed areas. Thrombus probability and subtraction maps were created to reveal the differences between the subgroups.

RESULTS

Remarkably, all patients with CVST-BD had thrombosis in the transverse sinus (TS). However, TS was affected in 73.9% of the CVST-O patients (17/17 in CVST-BD vs 17/23 in CVST-O, P = .03). Thrombosis developed mostly in the superior sagittal sinus (SSS) and TS in the CVST-O group (11/23, 47.8% and 17/23, 73.9%, respectively). The frequency of SSS thrombosis tended to be higher in the CVST-O (47.8% vs 23.5%, P = .19).

CONCLUSION

Venous infarction and hemorrhage were less common in patients with CVST-BD. The only clinical symptom in most of the CSVT patients with BD was headache due to elevated intracranial pressure. TS thrombosis was more common in patients with BD.

Update on the Diagnosis of Behçet's Disease

Behçet's disease (BD) is a systemic inflammatory disease with unknown etiology. It is characterized by recurrent mucocutaneous lesions and major organ disease such as ocular, neurologic, vascular, and gastrointestinal manifestations. The diagnosis of BD is mainly based on clinical manifestations after ruling out other potential causes. There are no specific laboratory, histopathologic, or genetic findings for the diagnosis of BD. The International Study Group (ISG) criteria set is still the most widely used set for the diagnosis. The main limitation of this criteria set is the lack of major organ manifestations such as vascular, neurologic, and gastrointestinal involvement. The ICBD 2014 criteria are more sensitive, especially in early disease. However, patients with such as spondyloarthritis can easily meet this criteria set, causing overdiagnosis. Diagnosing BD can be a big challenge in daily practice, especially in patients presenting with only major organ involvement such as posterior uveitis, neurologic, vascular, and gastrointestinal findings with or without oral ulcers. These patients do not meet ISG criteria and can be diagnosed with "expert opinion" in countries with high BD prevalence. The pathergy test is the only diagnostic test used as diagnostic or classification criteria for BD. Our recent studies showed that common femoral vein (CFV) thickness measurement can be a valuable, practical, and cheap diagnostic tool for BD with sensitivity and specificities higher than 80% for the cut-off value of 0.5 mm. However, the diagnostic accuracy of CFV measurement should be investigated in other disease groups in the differential diagnosis of BD and in also different ethnic populations.

Behçet- und Cogan-Syndrom

Das Behçet- und das Cogan-Syndrom bilden zusammen die Gruppe der Vaskulitiden der variablen Gefäße nach der Chapel-Hill Nomenklatur. Sie können Arterien und Venen jeder Größe betreffen. Wie die Bezeichnung „Syndrom“ bei beiden Krankheitsbildern bereits widerspiegelt, können beide individuell sehr unterschiedliche Symptome bieten. Beide zählen formal zu den seltenen Erkrankungen, wobei das Cogan-Syndrom mit der Beschreibung von lediglich einigen hundert Fällen weltweit deutlich seltener als das Behςet-Syndrom ist. Für letzteres gibt es Diagnose- und Klassifikationskriterien, und auch europäische (EULAR, European Alliance of Associations for Rheumatology) Therapieempfehlungen. Symptomatologie, Diagnostik und Therapie, aber auch einige Überlegungen zur Pathogenese dieser beiden Vaskulitiden werden im Folgenden beleuchtet.

Genetics in Behcet's Disease: An Update Review

Behcet's disease (BD) is one of the most vision-threatening clinical entities of uveitis. Although the etiopathogenesis of BD remains obscure, accumulating evidence has demonstrated that both genetic and environmental factors may contribute to the development of BD. Genome-wide association studies (GWAS) and candidate association studies have identified several genetic variants strongly associated with BD, including variants in human leukocyte antigen (HLA) -A02, -A03, -A24, -A26, -A31, -B15, -B27, -B35, -B49, -B51, -B57, -B58, -C0704, CIITA, ERAP1, MICA, IL1A-IL1B, IL10, IL12, IL23R, IL-23R/IL-12RB2, IL1RL1-IL18R1, STAT4, TFCP2L1, TRAF5, TNFAIP3, CCR1/CCR3, RIPK2, ADO-ZNF365-EGR2, KLRC4, LACC1, MEFV, IRF8, FUT2, CEBPB-PTPN1, ZMIZ1, RPS6KA4, IL10RA, SIPA1-FIBP-FOSL1, VAMP1, JRKL/CTCN5, IFNGR1 and miRNA-146a. Epigenetic modifications are also reported to play essential roles in the development of BD, including DNA methylation and histone modification. We review here the recent advances in the genetic and epigenetic factors associated with the BD pathogenesis.

Weak complex formation of adverse drug reaction-associated HLAB57, B58, and B15 molecules

The combination of certain human leukocyte antigen (HLA) polymorphisms with administration of certain drugs shows a strong correlation with developing drug hypersensitivity. Examples of typical combinations are HLA-B*57:01 with abacavir and HLA-B*15:02 with carbamazepine. However, despite belonging to the same serotype, HLA-B*57:03 and HLA-B*15:01 are not associated with drug hypersensitivity. Recent studies have shown that several HLA polymorphisms are associated with multiple drugs rather than a single drug, all resulting in drug hypersensitivity. In this study, we compared the molecular structures and intracellular localization of HLA-B*57:01, HLA-B*58:01, and HLA-B*15:02, which pose risks for developing drug hypersensitivity, as well as HLA-B*57:03 and HLA-B*15:01 that do not present such risks. We found that HLA molecules posing risks have a low affinity for the subunit β₂-microglobulin; notably, the weak hydrogen bond formed via Gln96 of the HLA molecule contributes to this behavior. We also clarified that these HLA molecules are easily accumulated in the endoplasmic reticulum, exhibiting a low expression on the cell surface. Considering that these hypersensitivity risk-associated HLA molecules form complexes with β₂-microglobulin and peptides in the endoplasmic reticulum, we assumed that their low complex formation ability in the endoplasmic reticulum facilitates the interaction with multiple drugs.

Progress in the genetics of uveitis

Uveitis is the most common form of intraocular inflammatory disease and is a significant cause of visual impairment worldwide. Aetiologically, uveitis can also be classified into infectious uveitis and non-infectious uveitis. The common non-infectious forms of uveitis include acute anterior uveitis (AAU), Behçet’s disease (BD), Vogt-Koyanagi-Harada (VKH) disease, birdshot chorioretinopathy (BSCR), sarcoid uveitis. In addition, a few monogenic autoinflammatory disorders can also cause uveitis, such as Blau Syndrome and haploinsufficiency of A20 (HA20). Although the exact pathogenesis of non-infectious uveitis is still unclear, it is well-recognised that it involves both genetic and environmental risk factors. A hallmark of uveitis is its strong associations with human leucocyte antigens (HLA). For examples, AAU, BD and BSCR are strongly associated with HLA-B27, HLA-B51, and HLA-A29, respectively. In uveitis studies, multiple GWAS have successfully been conducted and led to identification of novel susceptibility loci, for example, IL23R has been identified in BD, VKH and AAU. In this review, we summarize the latest progress on the genetic associations of both HLA and non-HLA genes with major forms of uveitis, including AAU, BD, VKH, BSCR, sarcoid uveitis, Blau Syndrome and HA20, and potential future research directions.

Pathogenesis of Behçet's Syndrome: Genetic, Environmental and Immunological Factors

Behçet's syndrome (BS) is a rare systemic vasculitis, characterized by a wide range of different clinical involvements and unpredictable phases of recurrence and remission. BS can be described as a multifactorial disease with an incompletely known etiopathogenesis; in fact, though presenting some peculiar features, such as its typical geographic distribution and the strong association with the well-known genetic predisposing factor HLA-B*51, the cause behind the onset and progression of the disease remains currently not fully understood. Besides genetic HLA and non-HLA predisposing associations and epigenetic influence, environmental factors also play an important role in the pathogenesis of the disease, and among these, infectious agents (both bacterial and viral) and specific microbiome alterations are considered of particular relevance in BS pathogenesis. BS has been included for decades among autoimmune diseases, in light of evidence showing T- and B-cell aberrant responses. However, because of recurrent mucocutaneous lesions and episodes of inflammation without antigen-specific T-cell or autoantibody responses, BS has also been classified among autoinflammatory disorders. Nevertheless, differently from autoinflammatory diseases, BS mildly responds to therapies targeting IL-1, its onset is not usually in childhood, and has high neutrophilic vasculitic involvement. Finally, given the association with HLA class I alleles, similar to spondyloarthropathies, the concept of BS as a major histocompatibility complex (MHC) I -opathy has been introduced. Understanding the complex etiopathogenesis of BS is essential to identify modifiable risk factors of BS occurrence or exacerbation and to develop targeted therapies. This review summarizes current evidence on the main genetic, environmental and immunological factors contributing to BS development.

Distinct transcriptional profile of blood mononuclear cells in Behçet's disease: insights into the central role of neutrophil chemotaxis

OBJECTIVES

Both innate and adaptive immune responses are reportedly increased in Behçet's disease (BD), a chronic, relapsing systemic vasculitis lying at the intersection between autoinflammation and autoimmunity. To further study pathophysiologic molecular mechanisms operating in BD, we searched for transcriptome-wide changes in blood mononuclear cells from these patients.

METHODS

We performed 3' mRNA next-generation sequencing-based genome-wide transcriptional profiling followed by analysis of differential expression signatures, Kyoto Encyclopedia of Genes and Genomes pathways, GO biological processes and transcription factor signatures.

RESULTS

Differential expression analysis clustered the transcriptomes of 13 patients and one healthy subject separately from those of 10 healthy age/gender-matched controls and one patient. Among the total of 17 591 expressed protein-coding genes, 209 and 31 genes were significantly upregulated and downregulated, respectively, in BD vs controls by at least 2-fold. The most upregulated genes comprised an abundance of CC- and CXC-chemokines. Remarkably, the 5 out of top 10 upregulated biological processes involved leucocyte recruitment to peripheral tissues, especially for neutrophils. Moreover, NF-kB, TNF and IL-1 signalling pathways were prominently enhanced in BD, while transcription factor activity analysis suggested that the NF-kB p65/RELA subunit action underlies the observed differences in the BD transcriptome.

CONCLUSION

This RNA-sequencing analysis in peripheral blood mononuclear cells derived from patients with BD does not support a major pathogenetic role for adaptive immunity-driven mechanisms, but clearly points to the action of aberrant innate immune responses with a central role played by upregulated neutrophil chemotaxis.

Immunological tests and their interpretation in uveitis

Uveitis is a complex disorder including both infectious and non-infectious etiologies. Clinical diagnosis is a challenge because many diseases share common clinical signs. Laboratory support is crucial for confirming the clinical diagnosis. Laboratory diagnosis includes direct tests and indirect tests. For example smear, culture, and molecular diagnostics demonstrate the pathogens, hence they are direct tests. Immunologic tests employ an antigen to detect presence of antibodies to a pathogen, or an antibody to detect the presence of an antigen, of the pathogen in the specimens. The immunological tests used in laboratories are made by producing artificial antibodies that exactly “match” the pathogen in question. When these antibodies come into contact with a sample they bind to the matching pathogen if found in the sample. Hence they are grouped under indirect evidence. There are several investigations in uveitis to reach the confirmed diagnosis including microbiological, immunological, imaging and molecular diagnostic testing. In this section we will discuss immunological investigations of infectious and non-infectious uveitis.

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.

A comprehensive overview on the genetics of Behçet's disease

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

Behçet disease (BD) and BD-like clinical phenotypes: NF-κB pathway in mucosal ulcerating diseases

Behçet's disease (BD) is a heterogeneous multi-organ disorder in search of a unified pathophysiological theory and classification. The disease frequently has overlapping features resembling other disease clusters, such as vasculitides, spondyloarthritides and thrombophilias with similar genetic risk variants, namely HLA-B*51, ERAP1, IL-10, IL-23R. Many of the BD manifestations, such as unprovoked recurrent episodes of inflammation and increased expression of IL-1, IL-6 and TNFα, overlap with those of the hereditary monogenic autoinflammatory syndromes, positioning BD at the crossroads between autoimmune and autoinflammatory syndromes. BD-like disease associates with various inborn errors of immunity, including familial Mediterranean fever, conditions related to dysregulated NF-κB activation (eg TNFAIP3, NFKB1, OTULIN, RELA, IKBKG) and either constitutional trisomy 8 or acquired trisomy 8 in myelodysplastic syndromes. We review here the recent advances in the immunopathology of BD, BD-like diseases and the NF-κB pathway suggesting new elements in the elusive BD etiopathogenesis.

Functional Genetic Polymorphisms in the IL1RL1-IL18R1 Region Confer Risk for Ocular Behçet's Disease in a Chinese Han Population

Single nucleotide polymorphisms (SNPs) in the IL1RL1–IL18R1 region are associated with various immune-mediated diseases. This study was carried out to investigate the causal variant for ocular Behçet’s disease (BD) and elucidate its target genes in the IL1RL1–IL18R1 region. Nine candidate functional SNPs were prioritized with bioinformatics analysis, followed by a two-stage association study in 694 ocular BD patients and 1,458 unaffected controls. Functional studies were performed in the peripheral blood mononuclear cells (PBMCs) of 45 healthy men and 16 active male BD patients. Genotyping was performed using the MassARRAY System. The mRNA expressions of IL1RL1, IL18R1, IL18RAP, and SLC9A4 were assayed by real-time PCR and secretion of cytokines was examined by ELISA. Significantly lower frequencies of the rs12987977 GG genotype/G allele (P_c = 8.93 × 10^–7, OR = 0.39; P_c = 2.60 × 10^–3, OR = 0.77, respectively), rs12999364 TT genotype/T allele (P_c = 3.15 × 10^–4, OR = 0.51; P_c = 1.13 × 10^–2, OR = 0.80, respectively), and rs4851569 AA genotype/A allele (P_c = 3.29 × 10^–4, OR = 0.52; P_c = 9.72 × 10^–3, OR = 0.80, respectively) were observed in BD patients compared with the controls. Functional experiments revealed a downregulation of IL1RL1, IL18R1, and SLC9A4 and a decreased secretion of IFN-γ in the anti-CD3/CD28 antibody-treated PBMCs as well as a decreased production of TNF-α in the lipopolysaccharide (LPS)-stimulated PBMCs in carriers of the protective homozygous rs12987977/GG genotype compared with the TT genotype. Our findings show that functional SNPs—rs12987977, rs12999364, and rs4851569—in the IL1RL1–IL18R1 region confer susceptibility to ocular BD in a Chinese Han population. And IL1RL1, IL18R1, and SLC9A4 may be the target genes of rs12987977.

Clusters in Pediatric Rheumatic Diseases

PURPOSE OF THE REVIEW

Rheumatic diseases usually have very diverse and complex pathophysiology resulting in different clinical phenotypes. Some certain phenotypes cluster together with a common presentation, course, and outcome. Our primary aim is to review the known disease clusters in certain rheumatological conditions.

RECENT FINDINGS

Cluster analysis has been reported in several rheumatic diseases, Behcet disease being the most common. Five individual clusters together with some clinical associations have been reported in Behcet patients. Certain antibody-phenotype associations and damage clusters have been reported in systemic lupus erythematosus (SLE) patients as well. Although there is no proper cluster analysis, two distinct phenotypes are evident in deficiency of ADA2 (DADA2): those with a polyarteritis nodosa-like vasculopathy and hematological involvement with pure red cell aplasia or bone marrow failure. The variants are claimed to be different regions of this gene for these 2 phenotypes. Lastly, there is a recent paper grouping ANCA-associated vasculitis according to disease phenotype and antibody associations. There are distinct clusters in certain rheumatic diseases which might help us to predict comorbidities, disease course, and treatment response.

Epidemiology of 2000 Chinese uveitis patients from Northeast China

Aims

To study the clinical characteristics of 2000 patients with uveitis admitted to the ophthalmology centre of the Second Hospital of Jilin University.

Methods

We retrospectively analysed 2000 patients with uveitis who were admitted to the uveitis clinic of the Second Hospital of Jilin University from July 2010 to June 2019 and analysed data on sex, onset age, onset season, anatomical classification, visual acuity and compared the results with those of other investigation studies.

Results

Among 2000 uveitis patients, the mean age of onset was 39.9±14.9 years. There were 946 male patients (47.3%) and 1054 female patients (52.7%). By anatomical classification, panuveitis was the most common (986 cases, 49.3%), followed by anterior uveitis (786 cases, 39.3%), posterior uveitis (119 cases, 6.0%) and intermediate uveitis (109 cases, 5.5%). Among anterior uveitis cases, ankylose spondylitis (207 cases, 26.34%), Fuchs syndrome (74 cases, 9.41%) and viral uveitis (71 cases, 9.03%) were the most common. Among panuveitis cases, Vogt-Koyanagi-Harada syndrome (372 cases, 37.73%), Behcet’s disease (142 cases, 14.40%) and sympathetic ophthalmitis (33 cases, 3.35%) were the most common. Uveitis often occurs during the autumn–winter transition period. The prevalence of anterior uveitis is highest in November, and statistical analysis shows that the incidence of uveitis has a significant correlation with the month. Panuveitis has the most significant effect on vision.

Conclusion

Panuveitis and anterior uveitis are the most common anatomical classifications of uveitis, which has a significant impact on vision, and their incidence is related to seasonal changes.

Redundancy and Complementarity between ERAP1 and ERAP2 Revealed by their Effects on the Behcet's Disease-associated HLA-B*51 Peptidome

The endoplasmic reticulum aminopeptidases ERAP1 and ERAP2 trim peptides to be loaded onto HLA molecules, including the main risk factor for Behçet's disease HLA-B*51. ERAP1 is also a risk factor among HLA-B*51-positive individuals, whereas no association is known with ERAP2. This study addressed the mutual relationships between both enzymes in the processing of an HLA-bound peptidome, interrogating their differential association with Behçet's disease. CRISPR/Cas9 was used to generate knock outs of ERAP1, ERAP2 or both from transfectant 721.221-HLA-B*51:01 cells. The surface expression of HLA-B*51 was reduced in all cases. The effects of depleting each or both enzymes on the B*51:01 peptidome were analyzed by quantitative label-free mass spectrometry. Substantial quantitative alterations of peptide length, subpeptidome balance, N-terminal residue usage, affinity and presentation of noncanonical ligands were observed. These effects were often different in the presence or absence of the other enzyme, revealing their mutual dependence. In the absence of ERAP1, ERAP2 showed similar and significant processing of B*51:01 ligands, indicating functional redundancy. The high overlap between the peptidomes of wildtype and double KO cells indicates that a large majority of B*51:01 ligands are present in the ER even in the absence of ERAP1/ERAP2. These results indicate that both enzymes have distinct, but complementary and partially redundant effects on the B*51:01 peptidome, leading to its optimization and maximal surface expression. The distinct effects of both enzymes on the HLA-B*51 peptidome provide a basis for their differential association with Behçet's disease and suggest a pathogenetic role of the B*51:01 peptidome.

Vasculitis: Decade in Review

BACKGROUND

In the last decade, we have come to better understand and manage the vasculitides. The classification of vasculitides has been revised. Genome- wide association studies and linkage analyses have been undertaken in hope of better understanding the pathogenesis of vasculitides. Comprehensive genetic studies have highlighted new pathways that may guide us in more targeted therapies. Description of the monogenic forms of vasculitis, such as deficiency of adenosine deaminase type 2 (DADA2), Haploinsufficiency of A20 (HA20), have introduced a new perspective to vasculopathies, and introduced alternative treatments for these diseases.

CONCLUSION

In this review, the important discoveries in pathogenesis and consensus treatment recommendations from the past decade will be summarized.

Immunopathogenesis of Behcet's Disease

Behcet's disease (BD) is a chronic systemic inflammatory vasculitis of unknown etiology characterized by recurrent episodes of oral aphthous ulcers, genital ulcers, skin lesions, ocular lesions, and other manifestations. Although the pathogenesis of BD is unclear, some studies have shown that immunological aberrations play an important role in the development and progression of BD. Infection-related trigger factors, including antigens and autoantigens, are believed to mediate the development of BD in patients with a genetic predisposition and subsequently activate the innate and adaptive immune systems, resulting in the production of numerous cytokines and chemokines to combat the infection-related factors. The study of the immunological mechanism of BD paves the way for the development of innovative therapies. Recently, novel biotherapy approaches, including interferon-α (IFN-α), tumor necrosis factor-α (TNF-α) antagonists, and other agents that target interleukins and their receptors, have shown promising results in the treatment of patients with refractory BD and have improved the prognosis of BD. In this review, we provide the current concepts of BD immunopathogenesis.

Behçet syndrome: A great imitator

Behçet syndrome is considered to be a multisystemic vasculitis involving the skin, mucosa, eyes, joints, nervous system, cardiovascular system, and gastrointestinal system. The exact pathogenesis of the disease is unknown, but autoimmune factors are thought to play the main role. Vasculitis in Behçet syndrome can involve any kind and size of vessels, and this explains why the disease has the ability of multisystemic involvement. The commonest clinical presentation of Behçet syndrome is recurrent and painful mucocutaneous ulcerations known as aphthosis. The other clinical manifestations vary among patients and populations. The disease tends to be more severe in men. Ocular, vascular, and central nervous system involvements are the major causes of morbidity and mortality. Behçet syndrome is a mimicker of many diseases with its several faces and considered as one of the great imitators in dermatology.

How ERAP1 and ERAP2 Shape the Peptidomes of Disease-Associated MHC-I Proteins

Four inflammatory diseases are strongly associated with Major Histocompatibility Complex class I (MHC-I) molecules: birdshot chorioretinopathy (HLA-A^*29:02), ankylosing spondylitis (HLA-B^*27), Behçet's disease (HLA-B^*51), and psoriasis (HLA-C^*06:02). The endoplasmic reticulum aminopeptidases (ERAP) 1 and 2 are also risk factors for these diseases. Since both enzymes are involved in the final processing steps of MHC-I ligands it is reasonable to assume that MHC-I-bound peptides play a significant pathogenetic role. This review will mainly focus on recent studies concerning the effects of ERAP1 and ERAP2 polymorphism and expression on shaping the peptidome of disease-associated MHC-I molecules in live cells. These studies will be discussed in the context of the distinct mechanisms and substrate preferences of both enzymes, their different patterns of genetic association with various diseases, the role of polymorphisms determining changes in enzymatic activity or expression levels, and the distinct peptidomes of disease-associated MHC-I allotypes. ERAP1 and ERAP2 polymorphism and expression induce significant changes in multiple MHC-I-bound peptidomes. These changes are MHC allotype-specific and, without excluding a degree of functional inter-dependence between both enzymes, reflect largely separate roles in their processing of MHC-I ligands. The studies reviewed here provide a molecular basis for the distinct patterns of genetic association of ERAP1 and ERAP2 with disease and for the pathogenetic role of peptides. The allotype-dependent alterations induced on distinct peptidomes may explain that the joint association of both enzymes and unrelated MHC-I alleles influence different pathological outcomes.

Association of LACC1, CEBPB-PTPN1, RIPK2 and ADO-EGR2 with ocular Behcet's disease in a Chinese Han population

Background

An Immunochip study recently identified the association of a number of new genetic loci with Behcet’s disease (BD).

Objective

To confirm the association between new genetic loci reported in an Immunochip study and BD in a Han Chinese population.

Methods

A two-stage association study was carried out in 1238 patients with BD and 1458 healthy controls. Twenty-two candidate single nucleotide polymorphisms (SNPs) were selected for genotyping by iPLEXGold genotyping or TaqMan SNP assays and a meta-analysis was performed for significantly associated markers.

Results

The results showed that four SNPs (LACC1/rs9316059, CEBPB-PTPN1/rs913678, ADO-EGR2/rs224127 and RIPK2/rs10094579) were associated with BD in an allelic association test (rs9316059 T allele: p_c=4.95×10⁻⁸, OR=0.687; rs913678 C allele: p_c=3.01×10⁻⁴, OR=1.297; rs224127 A allele: p_c=3.77×10⁻⁴, OR=1.274; rs10094579 A allele: p_c=6.93×10⁻⁴, OR=1.302). For four SNPs tested by meta-analysis, the association with BD was strengthened and all exceeded genome-wide significance (rs9316059: p=2.96×10⁻¹⁶; rs913678: p=2.09×10⁻¹⁶; rs224127: p=5.28×10⁻¹³; rs10094579: p=9.21×10⁻¹¹).

Conclusions

Our findings confirmed the association of four loci (LACC1, CEBPB-PTPN1, ADO-EGR2 and RIPK2) in Chinese Han patients with BD.

Knitting the Threads of Silk through Time: Behçet's Disease-Past, Present, and Future

Behçet's disease (BD) is a chronic relapsing vasculitis that affects vessels of all types and sizes with a broad spectrum of phenotypic heterogeneity and complex immunopathogenesis. Efforts by the scientific community to resolve the unmet needs of BD and gaps in our knowledge have been hampered by considerable challenges that primarily relate to the rare nature of the disease in many parts of the world and its heterogeneity. Controversies remain in many aspects of the disease including the diagnostic criteria, immunopathogenesis and biomarker discovery, geographical variation, and therapeutic considerations. In this review, we highlight recent advances in our scientific understanding of BD, shed new insights into diagnostic and treatment strategies, and discuss residual gaps in our knowledge that will serve as the basis for current and future research.

Dense genotyping of immune-related loci implicates host responses to microbial exposure in Behçet's disease susceptibility

We analyzed 1,900 Turkish Behçet’s disease cases and 1,779 controls genotyped with the Immunochip. The most significantly associated single nucleotide polymorphism (SNP) was rs1050502, a tag SNP for HLA-B*51. In the Turkish discovery set, we identified three novel loci, IL1A-IL1B, IRF8, and CEBPB-PTPN1, with genome-wide significance (P<5×10⁻⁸) by direct genotyping, and ADO-EGR2 by imputation. ADO-EGR2, IRF8, and CEBPB-PTPN1 replicated by genotyping 969 Iranian cases and 826 controls. Imputed data in 608 Japanese cases and 737 controls replicated ADO-EGR2 and IRF8 and meta-analysis additionally identified RIPK2 and LACC1. The disease-associated allele of rs4402765, the lead marker of the IL1A-IL1B locus, was associated with both decreased interleukin-1α and increased interleukin-1β production. ABO non-secretor genotypes of two ancestry-specific FUT2 SNPs showed strong disease association (P=5.89×10⁻¹⁵). Our findings extend shared susceptibility genes with Crohn’s disease and leprosy, and implicate mucosal factors and the innate immune response to microbial exposure in Behçet’s disease susceptibility.

Autoimmune sensorineural hearing loss as presenting manifestation of paediatric Behçet disease responding to adalimumab: a case report

Background

Autoimmune sensorineural hearing loss, also known as autoimmune inner ear disease (AIED) is a rare clinical entity characterized by progressive and bilateral sensorineural hearing loss often accompanied by vestibular symptoms. Diagnosis is essential as a consistent number of patients show a positive response to steroids alone or in association with other immunosuppressive drugs. AIED is defined as primary when the disease is limited to the ear, whereas in up to a third of cases it is associated to other systemic autoimmune diseases such as Behçet disease (BD).

BD is a rare multisystem vasculitis characterized by recurrent oral and genital aphtosis, uveitis, skin lesions, neurological and vascular manifestations. Clinical presentation is variable thus making the diagnosis difficult in many instances. The choice of therapy is also limited by the scarceness of high-quality therapy studies.

Case presentation

We present a 15-year-old-boy with six months of history of fever, dizziness, tinnitus and ataxia. He had a final diagnosis of AIED associated to BD and was successfully treated with the anti-tumor necrosis factor (TNF)-α adalimumab.

Conclusions

This case report points out to the diagnostic and therapeutic challenges of BD especially when unusual symptoms are the prominent manifestations of the disease. It also suggests that adalimumab is a good therapeutic option in children with BD and audiovestibular symptoms.

A Focus on the Epidemiology of Uveitis

PURPOSE

Uveitis is a common, sight-threatening inflammatory ocular disease and includes multiple heterogeneous clinical entities. The prevalence of various types of uveitis depends upon multiple factors, such as age, sex, race, geographic distribution, environmental influence, genetics, and social habits. Epidemiologic research of uveitis is necessary to understand the etiology and immunopathogenesis of this group of diseases. The present study attempts to concentrate on the most recent information on the epidemiology of uveitis and compare it with previous knowledge.

METHODS

An extensive literature search was performed in the Medline database (PubMed) and included surveys completed until 2015. Articles that reported prevalence and incidence were studied. References cited in the articles were also studied.

RESULTS

The incidence and prevalence of uveitis differs based on age, anatomic location of the inflammatory process (anterior, intermediate, posterior uveitis, panuveitis), gender, histopathology (granulomatous, non-granulomatous), type of inflammatory process (acute, chronic, recurrent), and etiology (infectious, non-infectious). Prevalence differs by geographic location. Idiopathic anterior uveitis is the most common form of uveitis in the community. Infectious causes are common (30-60%) in the developing countries. Herpes and toxoplasmosis are the leading infectious causes of uveitis. Non-infectious uveitic conditions are generally more common in the developed world. An increase in the prevalence of infectious etiologies, including tuberculosis and syphilis, has been seen in developed countries. Introduction of new treatment options has also changed patterns of disease.

CONCLUSIONS

Introduction of new uveitis entities, changes in the incidence of already known disease and increased availability of diagnostic testing have all altered the epidemiology of uveitis in recent years. Knowledge of regional patterns of disease is essential. A more detailed classification of uveitis with the establishment of uniform diagnostic criteria and prospective population based studies would certainly benefit epidemiologic research and clinical practice.

A 44-year-old man with eye, kidney, and brain dysfunction

Retinal vasculopathy with cerebral leukodystrophy (RVCL) is a rare, autosomal dominant condition caused by mutations of TREX1 (3-prime repair exonuclease-1). The phenotypic expressions range from isolated retinal involvement to varying degrees of retinopathy, cerebral infarction with calcium depositions, nephropathy, and hepatopathy. We report a case of RVCL caused by a novel TREX1 mutation. This patient's multisystem presentation, retinal involvement interpreted as "retinal vasculitis," and improvement of neuroimaging abnormalities with dexamethasone led to the accepted diagnosis of a rheumatologic disorder resembling Behçet disease. Clinicians should consider RVCL in any patient with retinal capillary obliterations associated with tumefactive brain lesions or nephropathy.

Molecular Genetic Advances in Uveitis

Uveitis is usually considered as an intraocular inflammation characterized by variety of clinical features. Behcet's disease (BD), Vogt-Koyanagi-Harada (VKH) syndrome, acute anterior uveitis (AAU), and birdshot chorioretinopathy (BCR) are examples of noninfectious forms of uveitis. Although the precise pathogenesis remains unclear, accumulating evidence shows that complex genetic backgrounds coupled with an aberrant immune response may be implicated in the development of uveitis. The complement and pattern recognition systems are both important factors of the innate immune system and are involved in the pathogenesis of uveitis. Copy number variants (CNVs) of complement component 4 have been found to be associated with BD and VKH syndrome, but not with AAU. Several CNVs and gene polymorphisms of toll-like receptors were found to be associated with BD. Leukocytes are an important part of the adaptive immune system and various molecules on these cells play an important role in the development of uveitis. Genes encoding for human leukocyte antigens (HLAs) have been shown to be associated with certain uveitis entities, including BD (HLA-B51), VKH syndrome (HLA-DR4, DRB1/DQA1), AAU (HLA-B27), and BCR (HLA-A29). Genome wide association studies showed that the IL-23R locus was a shared risk factor for multiple uveitis entities including BD, AAU, and VKH syndrome. In addition, various other non-HLA genes are also associated with BD or VKH syndrome, such as IL-10, STAT4, STAT3, and UBAC2. These studies support the hypothesis that genetic factors play a key role in the pathogenesis of uveitis.

Association of Higher Defensin β-4 Genomic Copy Numbers with Behçet's Disease in Iraqi Patients

OBJECTIVES

Behçet's disease (BD) is an immune-mediated small vessel systemic vasculitis. Human β-defensins are antimicrobial peptides associated with many inflammatory diseases and are encoded by the β-defensin family of multiple-copy genes. However, their role in BD necessitates further investigation. The aim of the present study was to investigate the possible association of BD in its various clinical forms with defensin β-4 (DEFB4) genomic copy numbers.

METHODS

This case-control study was conducted from January to September 2011 and included 50 control subjects and 27 unrelated Iraqi BD patients registered at Baghdad Teaching Hospital, Bagdad, Iraq. Copy numbers of the DEFB4 gene were determined using the comparative cycle threshold method by duplex real-time polymerase chain reaction technology at the Department of Dermatology of Jena University Hospital, Jena, Germany.

RESULTS

DEFB4 genomic copy numbers were significantly higher in the BD group compared to the control group (P = 0.010). However, no statistically significant association was found between copy numbers and clinical variables within the BD group.

CONCLUSION

The DEFB4 copy number polymorphism may be associated with BD; however, it is not associated with different clinical manifestations of the disease.

'MHC-I-opathy'-unified concept for spondyloarthritis and Behçet disease

The spondyloarthropathies comprise ankylosing spondylitis (AS), reactive arthritis, psoriatic arthritis (PsA) and arthritis associated with inflammatory bowel disease. In this Perspectives article, we describe how Behçet disease and several clinically distinct spondyloarthropathies-all associated with MHC class I (MHC-I) alleles such as HLA-B(*)51, HLA-C(*)0602 and HLA-B(*)27 and epistatic ERAP-1 interactions-have a shared immunopathogenetic basis. As a unifying concept, we propose that barrier dysfunction in environmentally exposed organs such as the skin, and aberrant innate immune reactions at sites of mechanical stress, can often trigger secondary adaptive immune CD8(+) T-cell responses with prominent neutrophilic inflammation that culminate in exacerbation and recurrence of these diseases. Of note, these 'MHC-I-opathies' show a differential immunopathology, probably reflecting antigenic differences within target tissues: HLA-B(*)51 is linked to ocular and mucocutaneous disease but not gut involvement, and HLA-C(*)0602 is linked to type I psoriasis but not scalp or nail disease.

The immunogenetics of Behçet's disease: A comprehensive review

Behçet's disease is a chronic multisystem inflammatory disorder characterized mainly by recurrent oral ulcers, ocular involvement, genital ulcers, and skin lesions, presenting with remissions and exacerbations. It is thought that both environmental and genetic factors contribute to its onset and development. Although the etiology of Behçet's disease remains unclear, recent immunogenetic findings are providing clues to its pathogenesis. In addition to the positive association of HLA-B*51, which was identified more than four decades ago, and which has since been confirmed in multiple populations, recent studies report additional independent associations in the major histocompatibility complex class I region. HLA-B*15, -B*27, -B*57, and -A*26 are independent risk factors for Behçet's disease, while HLA-B*49 and -A*03 are independent class I alleles that are protective for Behçet's disease. Genome-wide association studies have identified associations with genome-wide significance (P < 5 × 10(-8)) in the IL23R-IL12RB2, IL10, STAT4, CCR1-CCR3, KLRC4, ERAP1, TNFAIP3, and FUT2 loci. In addition, targeted next-generation sequencing has revealed the involvement of rare nonsynonymous variants of IL23R, TLR4, NOD2, and MEFV in Behçet's disease pathogenesis. Significant differences in gene function or mRNA expression associated with the risk alleles of the disease susceptibility loci suggest which genes in a disease-associated locus influence disease pathogenesis. These genes encompass both innate and adaptive immunity and confirm the importance of the predominant polarization towards helper T cell (Th) 1 versus Th2 cells, and the involvement of Th17 cells. In addition, epistasis observed between HLA-B*51 and the risk coding haplotype of the endoplasmic reticulum-associated protease, ERAP1, provides a clue that an HLA class I-peptide presentation-based mechanism contributes to this complex disease.

Equine recurrent uveitis: Human and equine perspectives

Equine recurrent uveitis (ERU) is a spontaneous disease characterised by repeated episodes of intraocular inflammation. The epidemiology of ERU has not been fully elucidated, but the condition appears to be much more common in horses than is recurrent uveitis in humans, especially in certain breeds and geographical regions. Both humans and horses show a similarly altered immune response and a marked autoimmune response as the primary disease pathophysiology. However, an inciting cause is not always clear. Potential inciting factors in horses include microbial agents such as Leptospira spp. Microbial factors and genetic predisposition to the disease may provide clues as to why the horse appears so susceptible to this disease. The aim of this review is to discuss the immunology and genetics of ERU, compare the disease in horses with autoimmune anterior uveitis in humans, and discuss potential reasons for the increased prevalence in the horse.

Pathogenesis of Behçet's disease: autoinflammatory features and beyond

Behçet's disease (BD) is an inflammatory disorder of unknown aetiology characterised by recurrent attacks affecting the mucocutaneous tissues, eyes, joints, blood vessels, brain and gastrointestinal tract. It is a multifactorial disease classified as a variable vessel vasculitis, and several environmental triggers may induce inflammatory episodes in genetically susceptible individuals. BD has several autoinflammatory features including recurrent self-limited clinical manifestations overlapping with monogenic autoinflammatory disorders, significant host predisposition and abnormally increased inflammatory response, with a robust innate component. Human leukocyte antigen (HLA)-B*51 is the strongest susceptibility factor described so far affecting the disease risk and typical phenotype. Non-HLA genetic associations such as endoplasmic reticulum aminopeptidase 1 (ERAP1), interleukin 23 receptor (IL23R) and IL10 variations suggest that BD shares susceptibility genes and inflammatory pathways with spondyloarthritis. Although genomewide association studies revealed an increased risk associated with recessively inherited ERAP1 variations in HLA-B*51 positive patients, it is not clear yet whether certain peptide-HLA allele combinations result in an adaptive response by a self-antigen-directed cytotoxic response or an innate response by modulating an NK cell activity or causing an unfolded protein response. Understanding of major histocompatibility complex (MHC) Class I-driven inflammatory response is expected to provide insights for the development of better treatment and remission-induction options in BD as well as in ankylosing spondylitis (AS) and psoriasis.

MATHEMATICAL MODELING OF BEHÇET'S DISEASE: A DYNAMICAL SYSTEMS APPROACH

Behçet's Disease (BD) is a multi-systemic, auto-inflammatory disorder that is characterized by recurrent episodes of inflammatory manifestations affecting skin, mucosa, eyes, blood vessels, joints and several other organs. BD is classified as a multifactorial disease with an important contribution of genetics. Genetic studies suggest that there is a strong association of BD with a Class I major histocompatibility complex antigen, named HLA-B*51, along with several other weaker associations with genes encoding proteins involved in inflammation. However, pathogenic mechanisms associated with these genetic variations and their interactions with the environment have not been elucidated yet. In this paper, we present a mathematical model for BD based on a dynamical systems perspective that captures especially the relapsing nature of the disease. We propose a disease progression mechanism and construct a model, in the form of coupled ordinary differential equations (ODEs), which reveals the occurrence pattern of the disease in the population. According to our model, the disease has three distinct modes describing different phenotypes of people carrying HLA-B*51 tissue antigen, namely, the Healthy Carrier, the Potential Patient and the Active Patient. We herein present an exemplary mathematical model for BD, for the first time in the literature, that concisely captures the actions of many cell types together with genetic and environmental effects. The proposed model provides insight into this complex inflammatory disease which may lead to identification of new tools for its treatment and prevention.

Biologics, colchicine, corticosteroids, immunosuppressants and interferon-alpha for Neuro-Behçet's Syndrome

BACKGROUND

Neuro-Behçet Syndrome (NBS) is a severe chronic inflammatory vascular disease involving the Central Nervous System (CNS), and it is an invalidating condition with disability and a huge impact on quality of life. Recommendations on treatments for NBS include the use of disease-modifying therapies in general, although they are not supported by a systematic review of the evidence.

OBJECTIVES

To assess the benefit and harms of available treatments for NBS, including biologics, colchicine, corticosteroids, immunosuppressants and interferon-alpha.

SEARCH METHODS

We searched the following databases up to 30 September 2014: Trials Specialised Register of The Cochrane Multiple Sclerosis and Rare Diseases of the Central Nervous System Group, CENTRAL, MEDLINE, EMBASE, CINAHL, LILACS, ORPHANET, Clinicaltrials.gov and World Health Organization (WHO) International Clinical Trials Registry Portal.

SELECTION CRITERIA

Randomised controlled trials (RCTs), controlled clinical trials (CCTs), prospective and retrospective controlled cohort studies were eligible to assess the benefit. Patients over 13 years of age with a diagnosis of NBS. For assessment of harms, open-label extension (OLE), case-control studies, population-based registries, case-series and case-reports were additionally planned to be evaluated.

DATA COLLECTION AND ANALYSIS

Selection of studies, data extraction and assessment of risk of bias were planned to be carried out independently by two review authors. Standard methodological procedures expected by The Cochrane Collaboration were followed. We planned to perform standard pair-wise meta-analyses for RCTs, and meta-analyses based on the adjusted estimates using the inverse-variance weighted average method for non-randomised studies (NRSs). We planned to present the main results of the review in a 'Summary of Findings' table using the GRADE approach.

MAIN RESULTS

No RCTs, CCTs or controlled cohort studies on the benefit of the treatments for NBS met the inclusion criteria of the review. Only one potentially eligible study was identified, but it did not report sufficient details on the patient characteristics. The author of this study did not provide additional data on request, and therefore it was excluded. Hence, no studies were included in the present review. Since no studies were included in the assessment of benefit, no further search was performed in order to collect data on harms.

AUTHORS' CONCLUSIONS

There is no evidence to support or refute the benefit of biologics, colchicine, corticosteroids, immunosuppressants and interferon-alpha for the treatment of patients with NBS. Thus, well-designed multicentre RCTs are needed in order to inform and guide clinical practice.

Genetics of Behçet's disease: lessons learned from genomewide association studies

PURPOSE OF REVIEW

Behçet's disease is a complex disease, and genetic susceptibility plays a critical role. This review aimed to discuss the recent genomewide association study (GWAS) findings and their implications to the pathogenesis of Behçet's disease.

RECENT FINDINGS

GWAS data confirmed the major role of HLA-B51 in Behçet's disease susceptibility, and the discovery of epistatic interactions between HLA-B51 and ERAP1 variants provided some hints about its possible pathogenic mechanisms. Investigation of human leukocyte antigen (HLA) Class I region showed weaker but independent associations around HLA-A and HLA-C regions. Genomewide studies also established associations with IL10, IL23R, CCR1, STAT4, KLRC4, GIMAP2/GIMAP4, and UBAC2 genes in Behçet's disease patients of different ethnicities. Deep resequencing of targeted genes identified additional associations with rare variants in TLR4, MEFV, and NOD2 genes.

SUMMARY

GWAS data established a major step forward by providing insights into the underlying mechanisms in Behçet's disease with the discovery of new susceptibility genes. These variations may implicate defects in the sensing and processing of microbial and endogenous danger signals as well as in the regulation of innate and adaptive immune responses in Behçet's disease. Association findings with HLA Class I antigens as well as IL23R, ERAP1, IL10, and MEFV genes also suggest shared inflammatory pathways with spondyloarthropathies.

Immunopathogenesis of ocular Behçet's disease

Behçet's disease (BD) is a chronic recurrent systemic inflammatory disorder of unknown etiology characterized by oral and genital ulcerations, skin lesions, and uveitis. The ocular involvement of BD, or Behçet's uveitis (BU), is characterized by panuveitis or posterior uveitis with occlusive retinal vasculitis and tends to be more recurrent and sight threatening than other endogenous autoimmune uveitides, despite aggressive immunosuppression. Although pathogenesis of BD is unclear, researches have revealed that immunological aberrations may be the cornerstone of BD development. General hypothesis of BD pathogenesis is that inflammatory response is initiated by infectious agents or autoantigens in patients with predisposing genetic factors and perpetuated by both innate and acquired immunity. In addition, a network of immune mediators plays a substantial role in the inflammatory cascade. Recently, we found that the immunopathogenesis of BU is distinct from other autoimmune uveitides regarding intraocular effector cell profiles, maturation markers of dendritic cells, and the cytokine/chemokine environment. In addition, accumulating evidence indicates the involvement of Th17 cells in BD and BU. Recent studies on genetics and biologics therapies in refractory BU also support the immunological association with the pathogenesis of BU. In this review, we provide an overview of novel findings regarding the immunopathogenesis of BU.

Behçet's syndrome pathophysiology and potential therapeutic targets

Behçet syndrome is a systemic inflammatory disorder characterized by multiorgan involvement such as oral and genital ulcers, uveitis, skin lesions as well as by less frequent, but often more severe, central nervous system and vascular manifestations. The pathogenetic mechanisms are still incompletely known; however the interaction between a specific genetic background and environmental or infectious factors certainly contributes to the immune dysregulation that characterizes this disease. The discovery of new immunological pathways in Behçet syndrome pathogenesis may help us to set up new treatments. In this review, we will focus our attention on the possible mechanisms underlying Behçet syndrome pathogenesis and their potential role as novel therapeutic targets.

The relationship between plasma homocysteine level and HLA-B51 in patients with Behcet's disease: a case-control study

BACKGROUND

Various coagulation disorders have been reported to explain hypercoagulability state in Behcet's disease (BD). A possible negative association between human leukocyte antigen (HLA)-B51 and increased homocysteine level has been suggested in a previous report from Iranian patients with BD. The aim of this study was to find any possible relationship between plasma homocysteine levels and HLA-B51.

METHODS

In a case-control study, BD patients (fulfilling the new International Criteria for BD) and controls (who had similar clinical symptoms but BD was clinically excluded in them) were included. Mean plasma homocysteine levels measured by enzyme-linked immunosorbent assay in HLA-B51 positive and negative individuals both in patients and controls were compared by t-test, Mann-Whitney test and analysis of variance (F-test).

RESULTS

Ninety-six BD patients and 152 controls were recruited. There was no significant difference between HLA-B51 positive and negative individuals either in the mean plasma homocysteine levels (13.59 ± 9.03 vs. 12.95 ± 4.98 μmol/L, P = 0.514), or in the prevalence of hyperhomocysteinemia (17% vs. 21.4%, P = 0.504). This was true both for BD and control groups. In HLA-B51 positive and negative BD patients, mean plasma homocysteine levels were 14.29 ± 12.02 and 12.62 ± 4.79 μmol/L, respectively (P = 0.33), and the prevalence of hyperhomocysteinemia was 20.8% versus 19.5% (P = 0.55). In the control group, the mean plasma homocysteine levels in HLA-B51 positive and negative individuals were 12.85 ± 4.28 and 13.14 ± 5.10 μmol/L, respectively (P = 0.794), and the prevalence of hyperhomocysteinemia was 13% versus 22.1% (P = 0.23). The difference was non-significant regarding sex (P > 0.71) and disease activity (P > 0.31).

CONCLUSION

In contrast to our previous report, we found no relationship between plasma homocysteine levels and HLA-B51 in this study, either in BD or in the control group.