Behçet's disease, the Silk Road and HLA-B51: historical and geographical perspectives

[Behçet's disease - ophthalmological and general aspects part I : etiology, pathogenesis and diagnostics]

Behçet's disease (also known as morbus Behcet or Admantiades-Behcet syndrome) is a chronic vasculitis mainly characterized by recurrent mucocutaneous lesions and sight threatening uveitis. It may also involve joints, vessels of all sizes and the central nervous system. Because of its severe morbidity and considerable mortality early diagnosis and treatment is important. Treatment and prognosis of this disorder have profited considerably in recent years following the introduction of biologic agents. This article summarizes the current state of knowledge and emphasizes the important role of the ophthalmologist in the diagnosis and therapy of Behçet's disease.

Targeted resequencing of candidate genes reveals novel variants associated with severe Behçet's uveitis

Behçet's disease (BD) is a chronic systemic inflammatory disorder characterized by four major manifestations: recurrent uveitis, oral and genital ulcers and skin lesions. To identify some pathogenic variants associated with severe Behçet's uveitis, we used targeted and massively parallel sequencing methods to explore the genetic diversity of target regions. A solution-based target enrichment kit was designed to capture whole-exonic regions of 132 candidate genes. Using a multiplexing strategy, 32 samples from patients with a severe type of Behçet's uveitis were sequenced with a Genome Analyzer IIx. We compared the frequency of each variant with that of 59 normal Korean controls, and selected five rare and eight common single-nucleotide variants as the candidates for a replication study. The selected variants were genotyped in 61 cases and 320 controls and, as a result, two rare and seven common variants showed significant associations with severe Behçet's uveitis (P<0.05). Some of these, including rs199955684 in KIR3DL3, rs1801133 in MTHFR, rs1051790 in MICA and rs1051456 in KIR2DL4, were predicted to be damaging by either the PolyPhen-2 or SIFT prediction program. Variants on FCGR3A (rs396991) and ICAM1 (rs5498) have been previously reported as susceptibility loci of this disease, and those on IFNAR1, MTFHR and MICA also replicated the previous reports at the gene level. The KIR3DL3 and KIR2DL4 genes are novel susceptibility genes that have not been reported in association with BD. In conclusion, this study showed that target enrichment and next-generation sequencing technologies can provide valuable information on the genetic predisposition for Behçet's uveitis.

Intense pulsed light in the treatment of telangiectasias: case report of Behçet's disease with superficial vascular involvement

Behçet's disease (BD) is a chronic systemic inflammatory disorder of unknown etiology with variable clinical manifestations. HLA-B51 allele is the most strongly associated known genetic factor. The mucocutaneous lesions (oral aphthae, genital aphthae, skin lesions such as pseudofolliculitis) constitute the hallmark of the disease, but also gastrointestinal, vascular, central nervous systems, and others may be involved. We report a case of a young man affected with Behçet's disease who presented facial telangiectasias and striae rubra in the inner region of his arms and at the level of his hips, as uncommon minor superficial vascular manifestations of BD. To manage them we have subjected the patient to a cycle of Intense Pulsed Light (IPL) therapy. Our findings showed that the use of IPL is a safe and effective treatment for telangiectasias and striae rubra, also in the complex clinical condition of Behçet's disease. In fact, the treatments were well tolerated, no sign of scarring or hyper/hypopigmentation was reported and we obtained a significant improvement of the lesions in terms of color and size of them.

Identification of a susceptibility locus in STAT4 for Behçet's disease in Han Chinese in a genome-wide association study

OBJECTIVE

To identify susceptibility loci for Behçet's disease (BD) and elucidate their functional role.

METHODS

A genome-wide association study (GWAS) and functional studies were conducted. A total of 149 patients and 951 controls were enrolled in the initial GWAS, and 554 patients and 1,159 controls were enrolled in the replication study. Real-time polymerase chain reaction, luciferase reporter assay, and enzyme-linked immunosorbent assay were performed.

RESULTS

Our GWAS and replication studies identified a susceptibility locus around STAT4 (single-nucleotide polymorphisms [SNPs] rs7574070, rs7572482, and rs897200; P = 3.36 × 10(-7) to 6.20 × 10(-9) ). Increased expression of STAT4 was observed in individuals carrying the rs897200 risk genotype AA. Consistent with the idea that STAT4 regulates the production of interleukin-17 (IL-17) and interferon-γ, IL17 messenger RNA and protein levels were increased in individuals carrying the rs897200 risk genotype AA. Interestingly, the risk allele A of rs897200 creates a putative transcription factor binding site. To test whether it directly affects STAT4 transcription, an in vitro luciferase reporter gene assay was performed. Higher transcription activity was observed in individuals carrying the risk allele A, suggesting that rs897200 is likely to directly affect STAT4 expression. Additionally, 2 SNPs, rs7574070 and rs7572482, which are tightly linked with rs897200, were cis-expression quantitative trait loci (eQTL) SNPs, suggesting that SNP rs897200 is an eQTL SNP. Most importantly, the clinical disease severity score was higher in individuals with the rs897200 risk genotype AA.

CONCLUSION

These findings strongly suggest that STAT4 is a novel locus underlying BD. We propose a model in which up-regulation of STAT4 expression and subsequent STAT4-driven production of inflammatory cytokines, such as IL-17, constitute a potential pathway leading to BD.

Behcet’s disease: a hardly diagnosed orphan disorder

Behcet’s disease is a multisystem autoimmune disease with variable clinial manifestations. The diagnosis may pose a difficult challenge for the clinician, who has to be familiar with the wide spectrum and combination of the symptoms of Behcet’s disease. It is considered a rare disease in Hungary, and there are only few reports on Behcet’s disease in the Hungarian literature. However, the past history of Hungary, the worldwide growing incidence of the disease, and the authors’ experience raise the possibility that the occurrence of the disease is higher than previously thought. In this review the authors present and discuss literature data on the pathogenesis and pathomechanism, as well as their own experience concerning the symptomatology of Behcet’s disease in order to promote diagnosis and offer adequate therapy for the patients. The authors presume that the importance of the disease is underestimated in Hungary due to a considerable number of unrecognized cases and they propose to establish a national registry for Behcets disease. Orv. Hetil., 2013, 154, 93–101.

Differential diagnosis and management of Behçet syndrome

Behçet syndrome (also known as Behçet disease) is a rare condition that is associated with considerable morbidity. Cases of Behçet syndrome have been reported worldwide, but the highest prevalence occurs in countries that border the ancient Silk Route, such as Turkey and Iran. Although oral ulceration, genital ulceration and eye disease are the classic triad of manifestations, the cardiovascular, gastrointestinal, musculoskeletal and central nervous systems can also be affected. The syndrome is chronic and relapsing with some patients having benign episodes whereas others have more serious complications, including blindness or the rupture of a pulmonary arterial aneurysm. Diagnosing Behçet syndrome, particularly outside of endemic regions, often incurs a considerable delay owing to the rarity of this condition. Furthermore, a paucity exists of data from randomized controlled trials on the optimal therapeutic approaches to use in patients, as well as a lack of informative laboratory surrogate markers to monitor disease progression. This Review discusses the issues surrounding the diagnosis and differential diagnosis of Behçet syndrome and presents the current approaches to managing patients with this complex group of disorders.

Two-stage association study in Chinese Han identifies two independent associations in CCR1/CCR3 locus as candidate for Behçet's disease susceptibility

Previous GWAS studies from Turkey suggested a potential risk locus at CCR1/CCR3 for Behçet's disease. However, this locus did not reach the GWAS significance threshold and has not yet been examined in other ethnic populations. The current study aimed to explore whether this locus was associated with Behçet's disease in Chinese Han and the functional role of the identified variants. A two-stage association study was performed in 653 patients and 1,685 controls using the iPLEX system. Real-time PCR was performed to examine the expression level of CCR1 and CCR3 genes. Haplotype analysis was used to construct the haplotype block. Logistic regression analysis was applied to calculate the independence of multiple associations. Bonferroni correction was applied to account for multiple testing. First stage analysis showed that ten SNPs, located in 3'UTR, 5'UTR in CCR1 or 5'UTR in CCR3, were significantly associated with Behçet's disease (P(c) = 0.018 to 1.3 × 10(-3)). The associations of six SNPs within this locus are independent after control for the genetic effect of rs17282391 using logistic regression analysis. Haplotype analysis identified three associated haplotypes: H3 (GTGAC), H6 (CCATTA) and H9 (CGA) (P(c) = 0.04 to 7.79 × 10(-4)). Three SNPs rs13084057, rs13092160 and rs13075270 showed consistent association in replication and combining studies (replication P(c) = 5.31 × 10(-5) to 1.44 × 10(-5); combining P(c) = 2.76 × 10(-7) to 6.50 × 10(-8)). Interestingly, eQTLs database reveals that SNP rs13092160 is eQTLs SNP, suggesting that this SNP is likely to be functional SNP that directly affects gene expression. The expression of CCR1 and CCR3 was increased in individuals with the CT genotype of rs13092160 (P < 0.05). No significant difference was found for the mRNA level of CCR1 and CCR3 between Behçet's patients and controls. These findings strongly indicate CCR1/CCR3 as a novel locus underlying Behçet's disease.

Contribution of Hla-B51 in the susceptibility and specific clinical features of Behcet's disease in Tunisian patients

BACKGROUND

Many researchers have tried to investigate the association of HLA-B51 with the severity and the clinical features of BD with conflicting results.

METHODS

We aimed at investigating the association of HLA-B51 with demographical and clinical manifestations as well as the severity of BD, by studying 178 native Tunisian BD patients, fulfilling the International Study group criteria for the BD classification recruited from the Department of Internal Medicine, Rabta Hospital in Tunis and compared with 125 native Tunisian healthy age and sex matching volunteers.

RESULTS

According to our findings, the frequency of HLAB 51 was significantly higher in BD patients than in controls (p<0.001). Positive pathergy test (PPT) (p = 0.01) and retinal vasculitis (p = 0.045), were significantly more frequent in HLA B51(+) patients, while the frequency of arterial aneurysms (p = 0.009) and neurological involvement, especially the parenchymal involvement (p<0.001), were significantly and clearly higher in HLA B51(-) patients. The patients without HLA B51 had a significantly less severe disease (p = 0.001). Discussion/conclusion We conclude that HLA B51 is a predisposing marker for BD in our population as in most ethnic groups. It seems to be associated with a subgroup of BD patients characterized by a higher frequency of ocular involvement and PPT, but a lower frequency of arterial aneurysm and neurological involvement, and a less severe disease course.

HLA gene and haplotype frequencies in Russians, Bashkirs and Tatars, living in the Chelyabinsk Region (Russian South Urals)

We have characterized the HLA-A, -B, -DRB1, -DQA1 and -DQB1 profiles of three major ethnic groups living in Chelyabinsk Region of Russian South Urals, viz., Russians (n = 207), Bashkirs (n = 146) and Tatars (n = 135). First field level typing was performed by PCR using sequence-specific primers. Estimates included carriage and gene frequencies, linkage disequilibrium and its significance and related values. Population comparisons were made between the allele family frequencies of the three populations and between these populations and 20 others using a dendrogram. Chelyabinsk Region Russians demonstrate all the features typical of a Caucasoid population, but also have some peculiarities. Together with Tatars, Russians have high frequencies of allele families and haplotypes characteristic of Finno-Ugric populations. This presupposes a Finno-Ugric impact on Russian and Tatar ethnogenesis. However, this was not apparent in Bashkirs, the first of the three populations to live in this territory, and implies admixture with populations of a Finno-Ugric origin with precursors of Russians and Tatars before they came to the South Urals. The Bashkirs appear close to Mongoloids in allele and haplotype distribution. However, Bashkirs cannot be labelled either as typical Mongoloids or as Caucasoids. Thus, Bashkirs possess some alleles and haplotypes frequent in Mongoloids, which supports the Turkic impact on Bashkir ethnogenesis, but also possess the AH 8.1 haplotype, which could evidence an ancient Caucasoid population that took part in their ethnic formation or of recent admixture with adjacent populations (Russians and Tatars). Bashkirs showed no features of populations with a substantial Finno-Ugric component, for example Chuvashes or Russian Saami. This disputes the commonly held belief of a Finno-Ugric origin for Bashkirs. Tatars appeared close to many European populations. However, they possessed some characteristics of Asiatic populations possibly reflecting a Mongoloid influence on Tatar ethnogenesis. Some aspects of HLA in Tatars appeared close to Chuvashes and Bulgarians, thus supporting the view that Tatars may be descendents of ancient Bulgars.

No association of PTPN22 polymorphisms with susceptibility to ocular Behcet's disease in two Chinese Han populations

BACKGROUND

Behcet's disease is known as a recurrent, multisystem inflammation and immune-related disease. Protein tyrosine phosphatase non-receptor 22 (PTPN22) is a key negative regulator of T lymphocytes and polymorphisms of the PTPN22 gene have been shown to be associated with various immune-related diseases. The present study was performed to assess the association between PTPN22 polymorphisms and Behcet's disease in two Chinese Han populations.

METHODOLOGY/PRINCIPAL FINDINGS

A total of 516 patients with ocular Behcet's disease and 690 healthy controls from two Chinese Han populations were genotyped by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method for three single nucleotide polymorphisms (SNPs). Hardy-Weinberg equilibrium was tested using the χ(2) test. Genotype frequencies were estimated through direct counting. Allele and genotype frequencies were compared between patients and controls using logistic regression analysis. The results revealed that there was no association between the tested three PTPN22 SNPs (rs2488457, rs1310182 and rs3789604) and ocular Behcet's disease (p>0.05). Categorization analysis according to the clinical features did not show any association of these three polymorphisms with these parameters (p>0.05).

CONCLUSIONS/SIGNIFICANCE

The investigated PTPN22 gene polymorphisms (rs2488457, rs1310182 and rs3789604) were not associated with ocular Behcet's disease in two Chinese Han populations, and showed that it may be different from other classical autoimmune diseases. More studies are needed to confirm these findings for Behcet's disease in other ethnic backgrounds.

Replication of a microsatellite genome-wide association study of Behcet's disease in a Korean population

OBJECTIVE

Behçet's disease is one of the major aetiologies of uveitis causing blindness in Asian countries. A genome-wide association study identified six microsatellite markers as disease susceptibility loci for Japanese patients with Behçet's disease. To confirm our recent results, these microsatellite markers were examined in a Korean population as a replication study.

METHODS

Study participants included 119 Behçet's disease patients and 141 controls. All were enrolled in Korea. Association between the six reported microsatellite markers (D3S0186i, D6S0014i, D6S0032i, 536G12A, D12S0645i and D22S0104i) and Behçet's disease was analysed. HLA-B was genotyped by sequence-based typing methods.

RESULTS

A microsatellite marker located near the HLA-B region demonstrated significant association with Behçet's disease (P = 0.028). The genotype and phenotype frequencies of the HLA-B*51 gene were significantly increased in patients (23.1 and 39.5%, respectively) compared with healthy controls (11.2 and 20.1%, respectively; P < 0.001).

CONCLUSION

Microsatellite analysis revealed that the HLA-B*51 gene was strongly associated with Behçet's disease in a Korean population.

Correlation of DEFA1 gene copy number variation with intestinal involvement in Behcet's disease

Copy number variation has been associated with various autoimmune diseases. We investigated the copy number (CN) of the DEFA1 gene encoding α-defensin-1 in samples from Korean individuals with Behcet's disease (BD) compared to healthy controls (HC). We recruited 55 BD patients and 35 HC. A duplex Taqman® real-time PCR assay was used to assess CN. Most samples (31.1%) had a CN of 5 with a mean CN of 5.4 ± 0.2. There was no significant difference in the CN of the DEFA1 gene between BD patients and HC. A high DEFA1 gene CN was significantly associated with intestinal involvement in BD patients. Variable DEFA1 gene CNs were observed in both BD patients and HC and a high DEFA1 gene CN may be associated with susceptibility to intestinal involvement in BD.

New insights in the clinical understanding of Behçet's disease

Behçet's disease is a chronic relapsing multisystemic inflammatory disorder characterized by four major symptoms (oral aphthous ulcers, genital ulcers, skin lesions, and ocular lesions) and occasionally by five minor symptoms (arthritis, gastrointestinal ulcers, epididymitis, vascular lesions, and central nervous system symptoms). Although the etiology of Behçet's disease is still unknown, there have been recent advances in immunopathogenic studies, genome-wide association studies, animal models, diagnostic markers, and new biological agents. These advances have improved the clinical understanding of Behçet's disease and have enabled us to develop new treatment strategies for this intractable disease, which remains one of the leading causes of blindness.

Potential Infectious Etiology of Behçet's Disease

Behçet's disease is a multisystem inflammatory disorder characterized by recurrent oral aphthous ulcers, genital ulcers, uveitis, and skin lesions. The cause of Behçet's disease remains unknown, but epidemiologic findings suggest that an autoimmune process is triggered by an environmental agent in a genetically predisposed individual. An infectious agent could operate through molecular mimicry, and subsequently the disease could be perpetuated by an abnormal immune response to an autoantigen in the absence of ongoing infection. Potentia bacterial are Saccharomyces cerevisiae, mycobacteria, Borrelia burgdorferi, Helicobacter pylori, Escherichia coli, Staphylococcus aureus, and Mycoplasma fermentans, but the most commonly investigated microorganism is Streptococcus sanguinis. The relationship between streptococcal infections and Behçet's disease is suggested by clinical observations that an unhygienic oral condition is frequently noted in the oral cavity of Behçet's disease patients. Several viral agents, including herpes simplex virus-1, hepatitis C virus, parvovirus B19, cytomegalovirus, Epstein-Barr virus and varicella zoster virus, may also have some role.

Ocular Behçet disease: current therapeutic approaches

PURPOSE OF REVIEW

To alert physician to timely recognition and current treatment of recurrent hypopyon iridocyclitis or panuveitis in ocular Behçet disease (OBD).

RECENT FINDINGS

Interferon-α, rituximab, intravitreal triamcinolone, and biological response modifiers by tumor necrosis factor inhibitors such as infliximab and adalimumab are being used increasingly for the treatment of severe sight-threatening ocular inflammation including retinal vasculitis and cystoid macular edema (CME).

SUMMARY

Biological agents offer tremendous potential in the treatment of OBD. Given that OBD predominantly afflicts the younger adults in their most productive years, dermatologist, rheumatologist, internist, or general practitioners supervising patients with oculo-articulo-oromucocutaneous syndromes should be aware of systemic Behçet disease. Early recognition of ocular involvement is important and such patients should strongly be instructed to visit immediately an ophthalmologist, as uveitis management differs from extraocular involvements with high ocular morbidity from sight-threatening complications due to relapsing inflammatory attacks in the posterior segment of the eye. A single infliximab infusion should be considered for the control of acute panuveitis, whereas repeated long-term infliximab infusions were proved to be more effective in reducing the number of episodes in refractory uveoretinitis with faster regression and complete remission of CME.

New insights into the pathogenesis of Behçet's disease

Behçet's disease (BD) is a recurrent systemic inflammatory disorder of unknown origin characterized by oral and genital mucous ulcer, uveitis, and skin lesions. Involvement of large vessels, central nervous system (CNS), gastrointestinal tract and thrombotic events are less frequent but can be life threatening. The aim of this review is to provide new insights into the pathogenesis of BD. Over the past year substantial advances have been done in the understanding of the genetic [1,2] and immunology [3] of BD. BD is at the crossroad between autoimmune and autoinflammatory syndromes. In common with autoimmune diseases BD shares class I MHC association. However, in contrast to autoimmune disorders, BD has clinical features that seem to be mostly autoinflammatory. The pathogenesis of BD is still unknown, but major determinants of the genetic and immune system abnormalities have been reported recently. Triggering infectious factors are supposed to participate in the outbreak of BD in genetically predisposed patients. Two recent large genome-wide association study (GWAS) conducted in Turkey and Japan reported association between single nucleotide polymorphism (SNP) of interleukin (IL)-10 and IL-23R/IL-12RB2 genes and BD. New insights into the perturbations of T cell homeostasis of BD recently emerged. We have recently demonstrated the promotion of Th17 responses and the suppression of regulatory T cells (Tregs) that were driven by interleukin (IL)-21 production and that correlates with BD activity. Inflammatory cells within BD inflammatory lesions included mostly neutrophils, Th1 and Th17 cells, and cytotoxic CD8+ and γδ T cells. Altogether, the recent progresses in the knowledge of BD pathogenesis pave the way for innovative therapy.

Clinical and Pathological Manifestations with Differential Diagnosis in Behçet's Disease

Behçet's disease is a multisystemic inflammatory disease of unknown etiology which usually occurs as a trait of symptoms: aphthous stomatitis, genital ulcerations, and ocular disease. At the beginning of the disease the diagnosis is uncertain because of various clinical manifestations and a long period up to the full clinical picture manifestation. Since neither the laboratory data nor the histopathological signs are truly pathognomonic in Behçet's disease, the differential diagnosis depends on a careful evaluation of the medical history and meticulous physical examination to detect concomitant systemic manifestations. Sometimes, some laboratory test may help establish the diagnosis. Subspecialty referral to ophthalmology, rheumatology, neurology, and gastroenterology should be considered when indicated.

Behçet's disease and genes within the major histocompatibility complex region

The role of genetic background in the development of Behçet's disease (BD) is best reflected by the strong association between HLA-B*51 and BD that has been demonstrated across various ethnic groups. The contributions made by other HLA or non-HLA genes to disease susceptibility have been suggested by the results of a number of gene association studies, although the true associations between the genes located within the major histocompatibility complex (MHC) region and BD have often been doubted due to the possibility of linkage disequilibrium of those genes with HLA-B*51. The presence of a true susceptibility gene in the vicinity of HLA-B*51 has also been extensively investigated because of the limited evidence that directly relates HLA-B*51 to the pathogenesis of BD. However, recent genome-wide association studies have confirmed that HLA-B*51 is primarily associated with BD and that there are multiple susceptibility loci other than HLA-B*51. In this review, we discuss BD-associated genes within the MHC region and their biological roles in the pathogenesis of BD.

Lack of an association of PD-1 and its ligand genes with Behcet's disease in a Chinese Han population

BACKGROUND

Behcet's disease is a chronic, multi-systemic autoimmune disease. Programmed cell death 1 (PD-1) gene is one of non-human leucocyte antigen genes. It has been demonstrated to be associated with several autoimmune diseases. However, only a few studies have addressed the association of ligand genes of PD-1, PD-L1 and PD-L2 with autoimmune disease. The purpose of this study was to analyze the potential association of the PD-1 and its ligand genes with Behcet's disease in a Chinese Han population.

METHODOLOGY/PRINCIPAL FINDINGS

Four single-nucleotide polymorphism (SNPs) rs2227981 and rs10204525 of PD-1, rs1970000 of PD-L1 and rs7854303 of PD-L2 were genotyped in 405 Behcet's patients and 414 age-, sex-, ethnic-matched healthy controls using polymerase chain reaction-restriction fragment length polymorphism assay. The results revealed that there were no significant differences in the genotype and allele frequencies of PD-1 rs2227981 and rs10204525 between the Behcet's patients and controls. A similar result was found for PD-L1 rs1970000 versus healthy controls. Only the C allele and the CC genotype of PD-L2 rs7854303 were identified in patients and controls. Stratification analysis based on gender and clinical findings did not show any associations between PD-1 or its ligand polymorphisms and Behcet's disease.

CONCLUSIONS/SIGNIFICANCE

None of the currently studied SNPs, PD-1 rs2227981 and rs10204525, PD-L1 rs1970000 and PD-L2 rs7854303, are associated with the susceptibility to Behcet's disease in a Chinese Han population. More studies are needed to confirm these findings in Behcet's patients with other ethnic backgrounds.

Behçet's Uveitis

Behçet's disease is a multisystem inflammatory disorder that is most common in countries along the ancient “Silk Road”. The eye is the most commonly involved vital organ in Behçet's patients and the typical form of involvement is a relapsing remitting panuveitis and retinal vasculitis. Uveitis is the initial manifestation of the disease in 10-15% of the patients. Anterior uveitis is always nongranulomatous. Diffuse vitritis, retinal infiltrates, sheathing of predominantly retinal veins, and occlusive vasculitis are the typical signs of posterior segment inflammation. Spontaneous resolution of acute inflammatory signs is a diagnostic feature. Fundus fluorescein angiography is the gold standard in monitoring inflammatory activity. Laser flare photometry is a useful noninvasive tool since flare readings correlate with fluorescein angiographic leakage. The most common complications are cataract, maculopathy, and optic atrophy. Male patients have a more severe disease course and worse visual prognosis. Immunomodulatory therapy is indicated in all patients with posterior segment involvement. Corticosteroids combined with azathioprine and/or cyclosporine is used initially. Biologic agents, including interferon alfa and infliximab, are used in resistant cases. Visual prognosis has improved in recent years with an earlier and more aggressive use of immunomodulatory therapy and the use of biologic agents in resistant cases.

Behçet's Syndrome and Thrombosis

Behçet syndrome (BS) is a multisystem vasculitis with unknown etiology and a unique geographic distribution. The disease course is characterized by exacerbations and remissions while abating as the years pass. The usual onset is in the third decade. Recurrent skin mucosa lesions and sight threatening panuveitis are the hallmark of the disease. Males are more severely affected than females. Vascular involvement can occur in up to 40% of cases. BS is unique among the vasculitides in that it may involve all sizes and types of vessels. It affects the veins more than the arteries. Lower extremity vein thrombosis is the most frequent manifestation of vascular involvement, followed by vena cava thrombosis, pulmonary artery aneurysms, Budd-Chiari syndrome, peripheral artery aneurysms, dural sinus thrombosis and abdominal aorta aneurysms. Vascular involvement is frequently associated with constitut onal symptoms and increased acute phase response and is the major cause of increased mortality. A predominantly neutrophilic vasculitis around the vaso vasorum is typical of BS. The thrombus is tightly adherent to the vessel wall which probably explains why thromboembolism is so rare despite the high frequency of venous disease. Thrombophilic factors do not seem to explain thrombotic tendency in BS. Immunosuppressive treatment is essential in suppression and preventing the attacks.

Genetics in ocular inflammation--basic principles

The ability to identify individuals at risk of ocular disease, or to determine the potential severity of disease or response to therapy is the current focus of much research. These studies are being led by genetic analysis of individuals to determine associations with alterations in gens that may explain manifestations of particular diseases. In this review we consider the basic principles behind genetic studies in general and of ocular disease in particular. We address the methodologies being utilised, and the results derived so far. The potential and pitfalls of such studies are relevant to the concept of personalised medicine and better defined clinical trials.

Behçet's disease exhibits an increased osteopontin serum level in active stage but no association with osteopontin and its receptor gene polymorphisms

Osteopontin (OPN) and its receptors have been reported to be involved in a number of autoimmune and inflammatory diseases. This study was designed to analyze the OPN serum level in Behçet's disease (BD) and the association of gene polymorphisms of OPN and its receptors with BD. The serum level of OPN in active BD patients, inactive BD patients, and controls was assayed by enzyme-linked immunosorbent assay. Four single nucleotide polymorphisms (SNPs) of OPN and 4 SNPs of OPN receptors were genotyped in 318 BD patients and 313 controls using a polymerase chain reaction restriction fragment length polymorphism assay. The OPN level was significantly increased in the serum of active BD patients compared with inactive BD patients and controls. SNP analysis indicated an increased frequency of the OPN rs1126772 A allele in BD patients compared with controls. However, the significance was lost after Bonferroni correction. The prevalence of other SNPs of OPN and its receptors did not differ between BD patients and controls. The results suggest that an increased serum OPN level was associated with clinical severity of BD. There was no association of the tested SNPs of OPN and its receptors with BD in Chinese Han patients.

Associations between the HLA-A polymorphism and the clinical manifestations of Behcet's disease

INTRODUCTION

The objective was to investigate associations between the HLA-A gene and Behcet's disease (BD) and its clinical manifestations.

METHODS

Genotyping for the HLA-A locus was performed using the polymerase chain reaction-Luminex typing method in 223 BD patients and 1,398 healthy controls.

RESULTS

The phenotypic frequencies of HLA-A*02:07 (odds ratio (OR) = 2.03, P = 0.002), A*26:01 (OR = 1.85, P = 0.008), and A*30:04 (OR = 2.51, P = 0.006) tended to be higher in BD patients than in normal controls, but the frequency of A*33:03 (OR = 0.59, P = 0.003) tended to be lower in BD patients. A meta-analysis adopting our and the Japanese data confirmed the associations of HLA-A*02:07, A*26:01, and A*33:03 with BD. Furthermore, the frequencies of the HLA-A*02:07, A*26:01, and A*30:04 were significantly higher in patients with skin lesions (OR = 2.37, P < 0.0005, Pc < 0.012) and arthritis (OR = 2.32, P = 0.002, Pc = 0.048), with uveitis (OR = 3.01, P < 0.0005, Pc < 0.012), and with vascular lesions (OR = 9.80, P < 0.0005, Pc < 0.012) and a positive pathergy test (OR = 4.10, P = 0.002, Pc = 0.048), respectively, than in controls. In HLA-B*51 non-carriers, these associations were also significant, being much stronger between HLA-A*26:01 and uveitis (OR = 4.19, P < 0.0005, Pc < 0.012) and between HLA-A*30:04 and vascular lesions (OR = 13.97, P < 0.00005, Pc < 0.0012). In addition, HLA-A*30:04 was associated with genital ulcers in HLA-B*51 non-carriers (OR = 3.89, P = 0.002, Pc = 0.048).

CONCLUSIONS

HLA-A*02:07, A*26:01, and A*30:04 were associated with increased risk for BD, while HLA-A*33:03 with decreased risk. HLA-A*02:07, A*26:01, and A*30:04 were associated with skin lesions and arthritis, with uveitis, and with vascular lesions, genital ulcers, and a positive pathergy test, respectively.

Behçet's syndrome

Behçet's syndrome is a systemic vasculitis with an unknown etiology affecting the small and large vessels of the venous and arterial systems. At least two clusters of disease expression have been described. The first includes superficial vein thrombosis, deep vein thrombosis, and dural sinus thrombi. The second includes acne, arthritis, and enthesitis. The presence of these clusters suggests there may be more than one disease mechanism operative in this complex disorder. Recent European League Against Rheumatism guidelines are useful for the management of the disease in organ systems distinct from the vascular, neurological, and gastrointestinal systems. This is because of a lack of controlled studies evaluating such vascular, neurological, and gastrointestinal complications.

Development of Behçet's disease in a Caucasian with human leukocyte antigen B51 after immigration to Japan

We herein report a 32-year-old Caucasian woman with human leukocyte antigen (HLA)-B51 who developed Behçet's disease after immigration to Japan. She was born and raised in Finland and had never experienced any clinical symptoms related to Behçet's disease before immigration to Japan. None of her family members in Finland had similar problems. Two years after the immigration, she developed typical clinical symptoms of Behçet's disease. This report strongly supports the canonical notion that the interaction of genetic factors, such as HLA-B51, with environmental factors specific to the countries in the Silk Road area, including Japan, may play a pivotal role in the pathogenesis of this disorder.

Genetic susceptibility to Behcet's disease: role of genes belonging to the MHC region

OBJECTIVE

To review the progress in the field of MHC-related genetic susceptibility to Behçet's disease (BD).

METHOD

Systematic review of the English literature between 1 January 1980 and 31 January 2010 using Medline. Case-control, population-based, observational cohort studies investigating the association between BD and HLA-B*51 subtypes, classical and non-classical HLA alleles and other HLA-related genes were selected. The geographical distribution of BD and these susceptibility genes was also taken into consideration. Case and familial case reports were excluded except for case series with more than two patients.

RESULTS

Ninety articles plus 17 obtained from other sources were included in the systematic review. We have found high evidence that a core component of genetic susceptibility to BD is within the MHC region being primarily related to an HLA-B*51 subtype: HLA-B*5101/B*510101. Moreover, HLA-A*26, HLA-B*15, HLA-B*5701 and TNF-α -1031C were independently associated with BD. Data suggest that other HLA (HLA-C, HLA-DR) and HLA-related [MHC Class I chain-related gene A (MIC-A), TNF-α] genes may play a role in BD co-susceptibility or pathogenesis. Finally, the distinctive geographical distribution of BD suggested an evolutionary selection of HLA-B*51 subtypes as the major susceptibility factors for BD.

CONCLUSION

Further studies must be addressed to clarify the functional relevance of the different genes found to be associated with disease susceptibility and the potential interactions between genes located within and outside the MHC region.

Study on association between polymorphism of HLA-DRB1 alleles and Behçet's disease

BACKGROUND

Behçet's disease (BD) is known to be associated with human leucocyte antigen (HLA)-B*51 in many ethnic groups. However, the association of HLA class II gene with BD has been described to be different according to different countries and regions.

OBJECTIVE

This study aims to investigate the association between polymorphism of HLA-DRB1 alleles and BD.

METHODS

Forty patients with BD and 100 healthy controls were typed for HLA-DRB1 alleles by the LABType SSO method.

RESULTS

The frequency of HLA-DRB1*14 was significantly higher in BD patients than in controls (P < 0.05), while the frequency of HLA-DRB1*15 was markedly lower in BD patients (P < 0.05). Regarding clinical manifestations, the frequency of HLA-DRB1*15 was significantly decreased in BD patients with genital ulcerations compared with controls (P < 0.05); the frequency of HLA-DRB1*14 was significantly increased in BD patients with erythema nodosum-like lesions and in BD patients with folliculitis-like lesions when compared to controls (P < 0.05, respectively). Moreover, the frequency of HLA-DRB1*14 was significantly increased in BD patients under 20 years of age at the onset of disease (P < 0.01), while the frequency of HLA-DRB1*15 was significantly decreased in them (P < 0.05), compared with controls.

CONCLUSION

The results suggested that HLA-DRB1 alleles might play an important role in the onset and clinical manifestations of BD.

STAT4 polymorphism in a Chinese Han population with Vogt-Koyanagi-Harada syndrome and Behçet's disease

This study investigated the association of rs7574865 polymorphism in STAT4 with Vogt-Koyanagi-Harada (VKH) syndrome and Behçet's disease (BD) in a Chinese Han population. Genotyping of rs7574865 polymorphism in the STAT4 gene was performed using polymerase chain reaction restriction fragment length polymorphisms in 379 VKH patients, 366 BD patients, and 414 controls. Of the samples, 20% were sequenced to validate polymerase chain reaction restriction fragment length polymorphism results. A binary logistic regression analysis was used to assess the influence of the gender on the association of STAT4 polymorphism with BD. A significantly increased frequency of TT genotype of the STAT4 rs7574865 was observed in VKH patients (p = 0.013). GT genotypic frequency was significantly lower in BD patients than in controls (p = 0.003) However the significance of rs7574865 was lost in all tested BD patients when adjusted for gender (p = 0.775). A significantly lower frequency of GT genotype and a significantly higher frequency of GG genotype was found in male BD patients compared with male controls (p = 0.000458 and p = 0.009, respectively). Stratification analysis according to tinnitus, alopecia, poliosis, headache, and vitiligo for VKH syndrome and oral ulceration, genital ulceration, skin lesions and arthritis for BD failed to find any association between the tested single nucleotide polymorphism and any of the extraocular findings. Our results suggest that TT genotype of rs7574865 may be a susceptible factor for VKH syndrome in a Chinese Han population, and that GG genotype of this SNP may confer susceptibility in male BD patients.

The contribution of Asian researchers to the field of rheumatology

Asia is home to more than half of the world's population and is a region of diverse ethnicity, culture, microbial endemicity, and economic backgrounds. This diversity is also reflected in the heterogeneity among Asian patients with rheumatic diseases in terms of clinical manifestations, disease courses, treatment responses and outcomes, which provides opportunities for researchers to conduct some unique studies. Several disease entities, such as Behçet syndrome, Takayasu arteritis, Kawasaki disease, and immunological disorders associated with human T-lymphotropic virus type 1 (HTLV-1), were first observed and defined in Asia. In addition, the region's researchers have been at the forefront of research in some interesting scientific topics, which has opened up new research avenues in rheumatology, such as the direct targeting of synovial cells in patients with rheumatoid arthritis via activation of the agonistic Fas pathway, establishment of the field of osteoimmunology, the discovery of regulatory T cells and synoviolin, and the development of tocilizumab, a humanized monoclonal antibody against interleukin-6 receptor.

[Ocular manifestations of Behçet's disease]

Eye involvement in Behçet's disease (BD) is frequent and an important cause of morbidity. The mean age at onset of uveitis is between 20 and 30 years in male and 30 years in female patients. Ocular involvement includes anterior, posterior or panuveitis. Uveitis may be the presenting manifestation of the disease in 20% of cases or may appear 2 or 3 years after the disease onset. The estimated risk of blindness at 5 years ranges from 15 to 25%. The main goals in the management of patients with BD uveitis are the rapid control of intraocular inflammation, the prevention of recurrent attacks, the achievement of complete remission, and preservation of vision. The medical treatment of patients with severe uveitis relies on the use of systemically administered drugs, including corticosteroids and cytotoxic agents. Anti-TNF agents and interferon-alpha seem to be efficient and well-tolerated alternative therapeutic options. Controlled clinical trials are mandatory to define the place of these new immunomodulatory agents in the therapeutic strategy, and especially their use as first-line therapy.

Current approach in the diagnosis and management of panuveitis

Panuveitis is a generalized inflammation of not only the whole of the uveal tract but also involves the retina and vitreous humor. It differs from other anatomical sites of inflammation in terms of causes as well as distribution. The common causes of panuveitis in our population are tuberculosis, Vogt-Koyanagi-Harada syndrome, sympathetic ophthalmia, Behcet's disease and sarcoidosis. A large number of cases still remain idiopathic. A stepwise approach is essential while evaluating these patients to be able to identify and treat the disease timely and correctly. Ancillary tests can be appropriately applied once the anatomic site of inflammation is identified. An exhaustive approach comprising a full battery of tests is obsolete. Only specific tailored investigations are ordered as suggested by the preliminary clinical and ocular examination. The mainstay of the treatment of uveitis is corticosteroids. Immunosuppressive agents are administered if the inflammation is not adequately controlled with corticosteroids. One of the recent breakthroughs in the treatment of refractory uveitis includes the introduction of immunomodulating drugs: Tumor necrosis factor-alpha antagonist and Interferon-alpha. Vitrectomy has been used in uveitis for over a few decades for diagnostic and therapeutic purposes. When compared to other anatomical sites of inflammation, panuveitis has poor visual outcome due to more widespread inflammation. The side-effects of the chronic treatment that these patients receive cannot be overlooked and should be specifically monitored under the supervision of an internist with special interest in inflammatory diseases.

HLA-B51/B5 and the risk of Behçet's disease: a systematic review and meta-analysis of case-control genetic association studies

OBJECTIVE

To quantify by meta-analysis the genetic effect of the HLA-B5 or HLA-B51 (HLA-B51/B5) allele on the risk of developing Behçet's disease (BD) and to look for potential effect modifiers.

METHODS

Relevant studies were identified using the PubMed Medline database and manual searches of the literature. Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated by using the random-effects model. Subgroup meta-analyses and meta-regression analyses were undertaken to investigate the effects of selected study-level parameters on the pooled OR. Heterogeneity was assessed using the I2 statistic. Pooled results were used to calculate population-attributable risks (PAR) for BD in relationship to HLA-B51/B5.

RESULTS

A total of 4,800 patients with BD and 16,289 controls from 78 independent studies (published 1975-2007) were selected. The pooled OR of HLA-B51/B5 allele carriers to develop BD compared with noncarriers was 5.78 (95% CI 5.00-6.67), with moderate between-study heterogeneity (I2 = 61%). The subgroup analyses stratifying studies by geographic locations (Eastern Asia, Middle East/North Africa, Southern Europe, Northern/Eastern Europe) yielded consistent OR ranges (5.31-7.20), with I2 ranges of 52-70%. Univariate random-effects meta-regression indicated the percentage of male BD cases (P = 0.008) as a source of heterogeneity. The PAR within the various geographic areas were estimated at 32-52%.

CONCLUSION

The strength of the association between BD and HLA-B51/B5, and its consistency across populations of various ethnicities, lends further support to this allele being a primary and causal risk determinant for BD. Variations according to sex support an interaction of this allele with BD characteristics.

HLA-B27 and HLA-B51 determination in Tunisian healthy subjects and patients with suspected ankylosing spondylitis and Behçet's disease

The aim of this retrospective study is to assess the frequency of HLA-B27 and HLA-B51 in healthy subjects from the center of Tunisia and to investigate their usefulness in the diagnosis of ankylosing spondylitis (AS) and Behçet's disease (BD), respectively. Microlymphocytotoxicity test was used to perform serologic HLA typing in a group of 124 healthy volunteers and a group of 365 patients suffering from clinical manifestations of AS and/or BD. HLA-B27 was found in 3.2% of healthy subjects and in 42.9% of patients with AS (P < 0.00006). HLA-B51 is, however, found in 16.1% of healthy subjects and in 30.0% of patients with BD (P > 0.05). Unlike HLA-B51, which seems to be as frequent in Tunisian patients with BD as in healthy subjects, HLA-B27 is more frequent in patients with AS than in controls. This highlights the usefulness of HLA-B27, rather than that of HLA-B51, in the diagnosis of the respective diseases.