Significant associations of HLA-B*5101 and B*5108, and lack of association of class II alleles with Behçet's disease in Italian patients

The relationship between HLA-B*51 subtypes, clinical manifestations and severity of Behçet's syndrome: a large Italian cohort study

Objectives

Behçet's syndrome (BS) is a chronic multisystemic inflammatory disorder of unclear aetiology. The predominant BS susceptibility locus was identified within HLA-B*51. HLA-B*51 subtypes were previously studied as disease susceptibility markers. Few data are now available about the relationship between B*51 subtypes and clinical phenotype. The aim of this study was to genotype HLA-B*51 subtypes in a series of Italian BS patients and to test the association with clinical manifestations and disease severity (Krause's index).

Methods

HLA-B*51 subtype genotyping for 63 alleles (B*51:01-B*51:63) was performed by PCR after DNA extraction from whole blood of BS patients. The correlation of disease clinical manifestations and severity (Krause's index) with the HLA-B*51 allele and its subtypes was analysed.

Results

We enrolled 241 (140 male and 101 female) BS patients, and HLA-B*51 frequency was 62.7% (151 of 241). One hundred and eight of the HLA-B*51-positive patients carried the B*51:01 subtype (108 of 151, 71.5%), 39 of 151 (25.8%) the B*51:08 subtype, 2 of 151 (1.3%) the B*51:02 subtype, 1 of 151 (0.7%) the B*51:05 subtype, and 1 of 151 (0.7%) the B*51:07 subtype. We found that ocular involvement was statistically associated with HLA-B*51 positivity and with B*51:01 and B*51:08 subtypes (P < 0.05). We also found that disease severity was higher in HLA-B*51-positive patients than in negative patients, but without statistical significance (median Krause's index 5.1 vs 4.1, P > 0.05).

Conclusion

Here, we confirm a high frequency of the HLA-B*51 allele in our group of BS patients. B*51:01 and B*51:08 were found to be the most common subtypes, and an association of both subtypes with ocular involvement was also underlined.

A plausible contributor to multiple sclerosis; presentation of antigenic myelin protein epitopes by major histocompatibility complexes

BACKGROUND

Multiple sclerosis (MS) can be induced upon successful presentation of myelin antigens by MHC I/II. Antigenic similarity between the myelin and viral proteins may worsen the immunological responses.

METHODOLOGY

Antigenic regions within myelin proteins; PLP1, MBP, MOG, and MAG were analyzed using SVMTrip and EMBOSS. Homology search identified sequence similarity between the predicted host epitopes and viral proteins. NetMHCpan predicted MHC I/II binding followed by peptide-protein docking through the HPEPDOCK server. Thereafter we analyzed conformational flexibility and stability of 15 protein-peptide complexes based on high docking scores. The binding free energy was calculated using conventional (MD) and Gaussian accelerated molecular dynamics simulation.

RESULTS

PLP1, MBP, MAG and MOG contained numerous antigenic epitopes. MBP and MOG epitopes had sequence similarity to HHV-6 BALF5; EBNA1 and CMV glycoprotein M (gM), and EBV LMP2B, gp350/220; HHV-8 ORFs respectively. Many herpes virus proteins like tegument, envelope glycoproteins, and ORFs of EBV, CMV, HHV-6, and HHV-8 demonstrated sequence similarity with MAG and PLP1. Some antigenic peptides were also linear B-cell epitopes and influenced cytokine production by T-cell. MHC I allele HLA-B*57:01 bound to PLP1 peptide and HLA-A*68:02 bound to a MAG peptide strongly. MHC II alleles HLA-DRB1*04:05 and HLA-DR1*01:01 associated with MAG- and MOG-derived peptides, respectively, demonstrating high HPEPDOCK scores. MD simulations established stable binding of certain peptides with the MHC namely HLA-B*51:01-MBP(DYKSAHKGFKGVDAQGTLSKIFKL), HLA-B*57:01-PLP1(PDKFVGITYALTVVWLLVFACSAVPVYIYF), HLA-DR1*01:01-MOG(VEDPFYWVSPGVLVLLAVLPVLLLQITVGLVFLCLQYR) and HLA-DRB1*04:05-MAG(TWVQVSLLHFVPTREA).

CONCLUSIONS

Cross-reactivity between self-antigens and pathogen derived immunodominant epitopes may induce MS. Our study supported the role of specific MHC alleles as a contributing MS risk factor.

HLA-B*51 allelic and carrier frequency in Kazakhstan: insights into Behçet's disease prevalence in Central Asia

Behçet's disease (BD) is a systemic vasculitis whose prevalence varies according to the ethnicity. HLA-B*51 is a well-known genetic factor predisposing to BD: populations with higher HLA-B*51 allelic frequencies are also those with a greater disease prevalence, as occurs in the Silk Road countries. However, the BD prevalence is unknown in many countries, including Kazakhstan and, in general, Central Asia, despite the location on or near the Silk Road. Due to the lack of clinical studies from this area, we analyzed the bone marrow donors registry in Kazakhstan, in order to assess the HLA-B*51 allelic and carrier frequencies, which resulted to be 8.14 and 15.28%, respectively. Through a comparison with the same parameters in other countries (by performing a data search in the medical literature and in the Allele Frequency Net Database), we might speculate a BD prevalence in Kazakhstan of 10-15/100.000 at least. This result should prompt a greater clinical consideration of this disease in Central Asia, as well as the publication of clinical data from this geographic area.

Behçet disease, new insights in disease associations and manifestations: a next-generation sequencing study

Behçet disease is a multi-system disease associated with human leukocyte antigen (HLA) class I polymorphism. High-resolution next-generation sequencing (NGS) with haplotype analysis has not been performed previously for this disease. Sixty Egyptian patients diagnosed according to the International Study Group (ISG) criteria for Behçet disease and 160 healthy geographic and ethnic-matched controls were genotyped for HLA class I loci (HLA-A, B, C). For HLA class II loci (DRB1, DRB3/4/5, DQA1, DQB1, DPA1, DPB1), 40 control samples were genotyped. High-resolution HLA genotyping was performed using NGS and the results were analyzed. Clinical manifestations were oral ulcers (100%), genital ulcers (100%), eye (55%) and neurological (28%) and vascular involvement (35%). HLA-B*51:08 [odds ratio (OR) = 19·75, 95% confidence interval (CI) = 6·5-79; P < 0·0001], HLA-B*15:03 (OR = 12·15, 95% CI = 3·7-50·7; P < 0·0001), HLA-C*16:02 (OR = 6·53, 95% CI = 3-14; P < 0·0001), HLA-A*68:02 (OR = 3·14, 95% CI = 1·1-8·9; P < 0·01) were found to be associated with Behçet disease, as were HLA-DRB1*13:01 and HLA-DQB1*06:03 (OR = 3·39, 95% CI = 0·9-18·9; P = 0·04 for both). By contrast, HLA-A*03:01 (OR = 0·13, 95% CI = 0-0·8; P = 0·01) and HLA-DPB1*17:01 were found to be protective (OR = 0·27, 95% CI = 0·06-1·03; P = 0·02). We identified strong linkage disequilibrium between HLA-B*51:08 and C*16:02 and A*02:01 in a haplotype associated with Behçet disease. HLA-B*51:08 was significantly associated with legal blindness (OR = 2·98, 95% CI = 1·06-8·3; P = 0·01). In Egyptian Behçet patients, HLA-B*51:08 is the most common susceptibility allele and holds poor prognosis for eye involvement.

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.

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

The strongest genetic risk factor of Behçet's disease (BD) is HLA-B*51. Our group previously reported that HLA-A*26 is independently associated with the risk of the onset of BD apart from HLA-B*51. Here, we re-evaluated the association between HLA-A*26 and BD in the Japanese population. We also performed a comprehensive literature search and meta-analyzed the extracted published data concerning the relationship between HLA-A*26 and BD to estimate the odds ratio (OR) of HLA-A*26 to BD. In this study, we genotyped 611 Japanese BD patients and 2,955 unrelated ethnically matched healthy controls. Genotyping results showed that the phenotype frequency of HLA-A*26 was higher in BD patients than in controls (OR = 2.12, 95% CI: 1.75-2.56). Furthermore, within the HLA-B*51-negative populations, the phenotype frequency of HLA-A*26 was significantly higher in BD patients than in controls (OR = 3.10, 95% CI: 2.43-3.95). Results obtained from meta-analysis combined with our data showed that the modified OR of HLA-A*26 became 1.80 (95% CI:1.58-2.06), whereas within the HLA-B*51-negative population, the modified OR became 4.02 (95% CI: 2.29-7.05). A subgroup analysis arranged by the geographical regions showed HLA-A*26 is in fact associated with the onset of BD in Northeast Asia (OR = 2.11, 95% CI: 1.75-2.56), but not in the Middle East or in Europe.

Genetics and immunodysfunction underlying Behçet's disease and immunomodulant treatment approaches

Behçet's disease (BD) is a chronic autoimmune condition primarily prevalent in populations along the Mediterranean Sea. The exact etiology of BD has not been fully explained yet, but the disease occurrence is associated with a genetic factor, human leukocyte antigen (HLA)-B51 antigen. Among the various immunodysfunctions that are found in BD, patients are increased neutrophil motility and superoxide production, as well as elevated production of tumor necrosis factor (TNF)-α and decreased production of interleukin (IL)-10. Elevated levels of inflammatory cytokines like IL-1 and IL-17 in BD have been found associated with aberrant expression of microRNA. Gene polymorphisms in BD patients have been observed in molecules involved in responses to pathogens that can ultimately modulate the host antimicrobial response. Moreover, several single nucleotide polymorphisms (SNPs) have been reported in genes encoding chemokines and adhesion molecules; many of these changes manifest as increases in vascular inflammation and vascular damage. Lastly, genetic and epigenetic changes have been suggested as involved in the pathogenesis of BD. Modifications in DNA methylation have been found in BD patient monocytes and lymphocytes, leading to adverse function of these cells. This review presents a comprehensive compilation of the literature with regard to the immunodysfunction underlying BD, as well as of the genetics, newly described clinical specifications and novel treatment strategies using immunomodulants based on the current understanding of BD.

The Behçet's disease-associated variant of the aminopeptidase ERAP1 shapes a low-affinity HLA-B*51 peptidome by differential subpeptidome processing

A low-activity variant of endoplasmic reticulum aminopeptidase 1 (ERAP1), Hap10, is associated with the autoinflammatory disorder Behçet's disease (BD) in epistasis with HLA-B*51, which is the main risk factor for this disorder. The role of Hap10 in BD pathogenesis is unknown. We sought to define the effects of Hap10 on the HLA-B*51 peptidome and to distinguish these effects from those due to HLA-B*51 polymorphisms unrelated to disease. The peptidome of the BD-associated HLA-B*51:08 subtype expressed in a Hap10-positive cell line was isolated, characterized by mass spectrometry, and compared with the HLA-B*51:01 peptidome from cells expressing more active ERAP1 allotypes. We additionally performed synthetic peptide digestions with recombinant ERAP1 variants and estimated peptide-binding affinity with standard algorithms. In the BD-associated ERAP1 context of B*51:08, longer peptides were generated; of the two major HLA-B*51 subpeptidomes with Pro-2 and Ala-2, the former one was significantly reduced, and the latter was increased and showed more ERAP1-susceptible N-terminal residues. These effects were readily explained by the low activity of Hap10 and the differential susceptibility of X-Pro and X-Ala bonds to ERAP1 trimming and together resulted in a significantly altered peptidome with lower affinity. The differences due to ERAP1 were clearly distinguished from those due to HLA-B*51 subtype polymorphism, which affected residue frequencies at internal positions of the peptide ligands. The alterations in the nature and affinity of HLA-B*51·peptide complexes probably affect T-cell and natural killer cell recognition, providing a sound basis for the joint association of ERAP1 and HLA-B*51 with BD.

HLA class I variation in Iranian Lur and Kurd populations: high haplotype and allotype diversity with an abundance of KIR ligands

HLA-A, -B and -C alleles of 285 individuals, representing three Iranian Lur populations and one Iranian Kurd population were sequenced completely, yielding human leukocyte antigen (HLA) class I genotypes at high resolution and filling four fields of the official HLA nomenclature. Each population has 87-99 alleles, evenly distributed between the three HLA class I genes, 145 alleles being identified in total. These alleles were already known, named and deposited in the HLA database. The alleles form 316 different HLA A-B-C haplotypes, with each population having between 80 and 112 haplotypes. The four Iranian populations form a related group that is distinguished from other populations, including other Iranians. All four KIR ligands - the A3/11, Bw4, C1 and C2 epitopes - are well represented, particularly Bw4, which is carried by three high-frequency allotypes: HLA-A*24:02, HLA-A*32:01 and HLA-B*51:01. In the Lur and Kurd populations, between 82% and 94% of individuals have the Bw4 epitope, the ligand for KIR3DL1. HLA-B*51:01 is likely of Neandertal origin and associated with Behcet's disease, also known as the Silk Road disease. The Lordegan Lur have the highest frequency of HLA-B*51:01 in the world. This allele is present on 46 Lur and Kurd haplotypes. Present at lower frequency is HLA-B*51:08, which is also associated with Behcet's disease. In the four Iranian populations, 31 haplotypes encode both Bw4(+) HLA-A and Bw4(+) HLA-B, a dual combination of Bw4 epitopes that is relatively rare in other populations, worldwide. This study both demonstrates and emphasizes the value of studying HLA class I polymorphism at highest resolution in anthropologically well-defined populations.

Genetic Association of HLA-A*26, -A*31, and -B*51 with Behcet's Disease in Saudi Patients

BACKGROUND

HLA-B*51 has been universally associated with Behcet’s disease (BD) susceptibility, while different alleles of HLA-A have also been identified as independent BD susceptibility loci in various ethnic populations. The objective of this study was to investigate associations of HLA-A and -B alleles with BD in Saudi patients.

MATERIALS AND METHODS

Genotyping for HLA-A and HLA-B was performed using HLA genotyping kit (Lab type^(R) SSO) in 120 Saudi subjects, including 60 BD patients and 60 matched healthy controls.

RESULTS

Our results revealed that frequencies of HLA-A*26, -A*31, and -B*51 were significantly higher in BD patients than in controls, suggesting that HLA-A*26, -A*31, and -B*51 are associated with BD. The frequency of HLA-B*15 was significantly lower in BD patients than in controls. Stratification of genotyping results into active and nonactive forms of BD revealed that the frequency of HLA-A*31 was significantly higher in the nonactive form than in the active form of BD, while there was no significant difference in the distribution of other alleles between the two forms of BD.

CONCLUSION

This study suggests that HLA-A*26, -A*31, and -B*51 are associated with susceptibility risk to BD, while HLA-B*15 may be protective in Saudi patients. However, larger scale studies are needed to confirm these findings.

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.

Characterization of the major histocompatibility complex locus association with Behçet's disease in Iran

Introduction

The aim of this study was to characterize the association of human leukocyte antigen (HLA) B alleles and major histocompatibility complex (MHC) single nucleotide polymorphisms (SNPs) with Behçet’s disease (BD) in an Iranian dataset.

Methods

The association of three SNPs in the MHC region previously identified as the most associated in high-density genotyping studies was tested in a case–control study on 973 BD patients and 825 controls from Iran, and the association of HLA-B alleles was tested in a subset of 681 patients and 414 controls.

Results

We found that HLA-B*51 (P = 4.11 × 10⁻⁴¹, OR [95% CI] = 4.63[3.66-5.85]) and B*15 confer risk for BD (P = 2.83 × 10⁻², OR [95% CI] = 1.75[1.08-2.84]) in Iranian, and in B*51 negative individuals, only the B*15 allele is significantly associated with BD (P = 2.51 × 10⁻³, OR [95% CI] = 2.40[1.37-4.20]). rs76546355, formerly known as rs116799036, located between HLA-B and MICA (MHC class I polypeptide-related sequence A), demonstrated the same level of association with BD as HLA-B*51 (P_adj = 1.78 × 10⁻⁴⁶, OR [95% CI] = 5.46[4.21-7.09], and P_adj = 8.34 × 10⁻⁴⁸, OR [95% CI] = 5.44[4.20-7.05], respectively) in the HLA-B allelotyped subset, while rs2848713 was less associated (P_adj = 7.14 × 10⁻³⁵, OR [95% CI] = 3.73[2.97-4.69]) and rs9260997 was not associated (P_adj = 1.00 × 10⁻¹). Additionally, we found that B*51 genotype-phenotype correlations do not survive Bonferroni correction, while carriers of the rs76546355 risk allele predominate in BD cases with genital ulcers, positive pathergy test and positive BD family history (2.31 × 10⁻⁴ ≤ P ≤ 1.59 × 10⁻³).

Conclusions

We found that the HLA-B*51 allele and the rs76546355/rs116799036 MHC SNP are independent genetic risk factors for BD in Iranian, and that positivity for the rs76546355/rs116799036 risk allele, but not for B*51, does correlate with specific demographic characteristics or clinical manifestations in BD patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0585-6) contains supplementary material, which is available to authorized users.

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.

HLA and non-HLA genes in Behçet's disease: a multicentric study in the Spanish population

Introduction

According to genome wide association (GWA) studies as well as candidate gene approaches, Behçet’s disease (BD) is associated with human leukocyte antigen (HLA)-A and HLA-B gene regions. The HLA-B51 has been consistently associated with the disease, but the role of other HLA class I molecules remains controversial. Recently, variants in non-HLA genes have also been associated with BD. The aims of this study were to further investigate the influence of the HLA region in BD and to explore the relationship with non-HLA genes recently described to be associated in other populations.

Methods

This study included 304 BD patients and 313 ethnically matched controls. HLA-A and HLA-B low resolution typing was carried out by PCR-SSOP Luminex. Eleven tag single nucleotide polymorphisms (SNPs) located outside of the HLA-region, previously described associated with the disease in GWA studies and having a minor allele frequency in Caucasians greater than 0.15 were genotyped using TaqMan assays. Phenotypic and genotypic frequencies were estimated by direct counting and distributions were compared using the χ² test.

Results

In addition to HLA-B*51, HLA-B*57 was found as a risk factor in BD, whereas, B*35 was found to be protective. Other HLA-A and B specificities were suggestive of association with the disease as risk (A*02 and A*24) or protective factors (A*03 and B*58). Regarding the non-HLA genes, the three SNPs located in IL23R and one of the SNPs in IL10 were found to be significantly associated with susceptibility to BD in our population.

Conclusion

Different HLA specificities are associated with Behçet’s disease in addition to B*51. Other non-HLA genes, such as IL23R and IL-10, play a role in the susceptibility to the disease.

Genetic and non-genetic factors affecting the visual outcome of ocular Behcet's disease

OBJECTIVE

To examine the prognostic factors for visual outcome in Korean BD patients with uveitis.

METHODS

Seventy-seven Korean BD patients with uveitis were enrolled. HLA-B and HLA-A genotypes were determined by PCR-based method. Visual acuity was measured by Snellen chart. Vision loss was graded into visual impairment (VI) defined as VA<20/40 for more than 6 months, loss of useful vision (LUV) as VA < 20/200, and near total blindness (NTB) as VA of light perception or worse.

RESULTS

VI was associated with a longer duration of uveitis, posterior uveitis, and cataract, LUV with male gender, a longer duration of uveitis, posterior uveitis, and cataract, and NTB with a longer duration of uveitis, cataract, and glaucoma. HLA-B*51 and HLA-A*26:01 did not show any association with VI, LUV, or NTB. However, HLA-B*51 carriers had earlier onset of uveitis and HLA-A*26:01 was strongly associated with posterior uveitis. In patients with posterior uveitis, VI was associated with a longer duration of uveitis and cataract, LUV with a longer duration, and NTB with HLA-B*51.

CONCLUSION

Longer duration of uveitis, posterior uveitis, male gender, cataract, and glaucoma were found to be associated with poor visual outcome in BD-related uveitis. HLA-B*51 was associated with NTB in patients with posterior uveitis. HLA-A*26:01 showed no association with VI, LUV, or NTB, however, was strongly associated with posterior uveitis.

A comparative study of the genetics of Behcet's disease in Iraq: international collaboration to transfer clinical and laboratory skills to Baghdad medical school and hospitals

A collaborative project funded by the Iraqi Research Fellowship Programme of the Council for Assisting Refugee Academics was set up to transfer laboratory and clinical skills in between three clinical research teams in the UK, Jordan and Iraq. The project was set up to study the genetics of the potentially debilitating condition, Behçet's Disease (BD). Blood samples were collected from: 38 BD patients, 28 patients with oral ulcers not related to BD and 32 healthy controls. All samples were analysed using Micro SSP HLA Class I B locus kit (B locus, generic). Logistic regression analysis revealed that samples positive for HLA-B51 were 7.4 times more likely to have BD than the healthy control subjects. The results of this study make a valuable addition to the scientific literature. Additional valuable outcomes include the intellectual exchange and transfer of skills in between the collaborating teams, which led to the establishment of an international research collaboration.

Laboratory support in the diagnosis of uveitis

Intraocular inflammations are still a diagnostic challenge for ophthalmologists. It is often difficult to make a precise etiological diagnosis in certain situations. Recently, there have been several advances in the investigations of uveitis, which has helped the ophthalmologists a lot in the management of such clinical conditions. A tailored approach to laboratory diagnosis of uveitic cases should be directed by the history, patient's symptoms and signs, and clinical examination. This review summarizes various modalities of laboratory investigations and their role in the diagnosis of uveitis.

HLA-A, B (Class I) and HLA-DR, DQ (Class II) antigens in Turkish patients with recurrent aphthous ulceration and Behçet's disease

OBJECTIVE

The aims of the present study were to typify the human leukocyte antigen system (HLA)-A, B (class I) and HLA-DR, DQ (class II) antigens and to assess the frequency of the presence of these antigens in the Turkish population with recurrent aphthous ulceration (RAU) and Behçet's disease (BD) compared to healthy subjects.

SUBJECTS AND METHODS

Thirty patients with RAU, 30 with BD, and 15 healthy subjects were included in the study. HLA typing was performed by serology with commercial kits for HLA class I and II (One Lambda, Canoga Park, Calif., USA).

RESULTS

The HLA-A23 frequency was 26.7% in the RAU patients, which was significantly higher than the 3.3% frequency in the patients with BD (p < 0.05). The HLA-A24 frequency was 33.3% in the RAU patient group, which was significantly higher (p < 0.05) than the frequency in the healthy subjects (6.7%). Significantly higher frequencies (46.7%) of HLA-A30 were found in the healthy subjects compared to the BD (13.3%) and RAU (3.3%) patients (p < 0.05 and p < 0.01, respectively). A higher frequency of HLA-B13 was observed in the RAU (23.3%) patients compared to the BD (0%) patients (p < 0.01). A decrease was observed in HLA-DR10 and HLA-DR17 in the RAU patients (p < 0.05), while a higher frequency of HLA-DR10 was observed in the BD patients compared to the RAU patients (p < 0.01).

CONCLUSIONS

These results showed that RAU and BD were not in the same spectrum and the involvement of other genetic and/or environmental factors might be responsible for the development of these diseases and/or disease progression.

Ancillary testing, diagnostic/classification criteria and severity grading in Behçet disease

Since there is no pathognomonic clinical sign or laboratory test to distinguish Behçet disease from other uveitic entities, the diagnosis must be made based on characteristic ocular and systemic findings in the absence of evidence of other disease that can explain the findings. Ancillary tests, including ocular and brain imaging studies, are used to assess the severity of intraocular inflammation and systemic manifestations of Behçet disease, to identify latent infections and other medical conditions that might worsen with systemic treatment, and to monitor for adverse effects of drugs used. There are two diagnostic or classification criteria in general use by the uveitis community, one from Japan and one from an international group; both rely on a minimum number and/or combination of clinical findings to identify Behçet disease. Finally, several grading schemes have been proposed to assess severity of ocular disease and response to treatment.

Replication study confirms the association between UBAC2 and Behçet's disease in two independent Chinese sets of patients and controls

Introduction

The purpose of this study was to replicate genetic factors associated with the susceptibility to Behçet's disease (BD). We conducted a two-stage candidate genes association and functional study, involving 477 BD patients and 1,334 normal controls of Chinese Han descent.

Methods

The genotyping of five candidate genes/loci, including LOC100129342, KIAA1529, CPVL, UBASH3B and UBAC2, were performed using TaqMan single nucleotide polymorphism (SNP) assays. Real-time PCR and luciferase reporter assay were performed to test the function of the identified promoter polymorphism. The main outcome measures were genotype frequencies and expression levels in BD patients.

Results

The first-stage study results showed that UBAC2 (rs9513584, Pc = 0.018, OR = 1.4), but not LOC100129342, KIAA1529, CPVL, UBASH3B was associated with the susceptibility to BD in Chinese Han. The fine-mapping association study of UBAC2 identified six risk SNPs for BD in the Chinese cohort; three of them were verified in validation study (rs3825427, first-stage Pc = 2.2 × 10^-3, second-stage Pc = 9.3 × 10^-3, combined Pc = 6.9 × 10^-6; rs9517668, first-stage Pc = 1.7 × 10^-3, second-stage Pc = 0.03, combined Pc = 3.3 × 10^-4; rs9517701, first-stage Pc = 5.1 × 10^-3, second-stage Pc = 9.0 × 10^-3, combined Pc = 2.9 × 10^-5; respectively). Functional analysis showed that the risk T allele of the promoter polymorphism rs3825427 had a significantly lower promoter activity than the non-risk G allele (P = 0.002) and a decreased expression of UBAC2 transcript variant 1 in peripheral blood mononuclear cells (PBMCs) and skin of normal controls carrying the risk T allele than that in individuals with the G allele (P = 0.045, P = 0.025; respectively). The mRNA expression of UBAC2 transcript variant 1 was significantly decreased in PBMCs and skin of BD patients as compared with controls (P = 0.025; P = 0.047, respectively). The mRNA expression of UBAC2 transcript variant 2 was significantly increased in skin of BD patients as compared with controls (P = 0.004).

Conclusions

This study replicates a predisposition gene to BD, UBAC2, and suggests that UBAC2 may be involved in the development of BD through its transcriptional modulation.

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.

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.

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.

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.

A study on thrombophilic factors in Italian Behcet's patients

BACKGROUND

Behcet's disease (BD) may complicate with arterial and venous thrombosis. The purpose of this work is to evaluate in an Italian group of BD patients with thrombotic events a large panel of inherited and acquired thrombophilic factors.

METHODS

Thirty BD patients, of which nine with previously arterial or venous thrombosis and 21 without, underwent the following investigations: plasma antithrombin activity, protein C activity, free protein S level, sensitivity to APC, total plasma homocysteine concentration, serum folate level, determination of anti-phospholipid antibodies, serum Lp(a) levels, tests for gene polymorphisms of factor V Leiden, prothrombin and methylenetetrahydrofolate reductase genes. Tests for the gene polymorphisms were also performed in a group of healthy control subjects.

RESULTS

All the six patients with arterial or deep venous thrombosis showed thrombophilic conditions such as protein C or protein S deficiency (one case each), hyperhomocysteinemia (two cases), positivity of anti-phospholipid antibodies associated with APC resistance or hyperhomocysteinemia (one case each). Among three subjects with superficial thrombophlebitis only one showed a mild hyperhomocysteinemia. No differences were found between BD patients and control subjects concerning polymorphisms of the genes considered. Among BD patients the Factor V H1299R mutation showed a weak association with venous thrombosis (P=0.048).

CONCLUSION

In BD patients different concomitant significant thrombophilic risk factors may contribute to the development of thrombotic events. Patients affected by vasculo-Behcet should be evaluated for the presence of coexisting major thrombophilic conditions.

Genetics of Behçet disease inside and outside the MHC

BACKGROUND

Behçet disease (BD) is a rare, chronic, systemic, inflammatory disorder characterised by recurrent ocular, genital and skin lesions. Although its aetiology is still uncertain, an intricate interplay between the environment (eg, viruses) and the host seems to initiate and/or perpetuate the disease, although the mechanism remains speculative. Since the identification of HLA-B*5101 (and more recently of MICA) as a susceptibility locus for BD, the identification of additional genetic locus/loci, whether inside, or perhaps more importantly outside the MHC has clearly stalled.

OBJECTIVE

To carry out a genome-wide association study (GWAS) of BD.

METHODS

300 Japanese patients with BD and an equal number of controls were recruited. The samples were screened using a dense panel of 23 465 microsatellites (MS) covering the entire genome.

RESULTS

The six best (of a total of 147) positively associated MS with BD were identified. Of these six, two were located within the human leucocyte antigen (HLA) class I region itself. Although one of these was clearly reminiscent of the association with HLA-B, the second, not in linkage disequilibrium with the former, was in the telomeric side of the class I region and remained to be formally identified. HLA genotyping and haplotype analysis conclusively led to the deciphering of a dual, independent, contribution of two HLA alleles to the pathogenesis of BD: HLA-B*5101 and HLA-A*26.

CONCLUSIONS

This GWAS highlights the premier genetic susceptibility locus for BD as the major histocompatibility complex itself, wherein reside two independent loci: HLA-B and HLA-A.

The novel –G646A polymorphism of the TNFα promoter is associated with the HLA‐B51 allele in Korean patients with Behçet's disease

OBJECTIVE

This study was performed to examine the influence of tumour necrosis factor-alpha (TNFalpha) promoter polymorphisms on disease susceptibility and clinical features of Behçet's disease (BD) and the association between TNFalpha polymorphisms and human leucocyte antigen (HLA)-B51.

METHODS

We examined 115 patients with BD and 114 healthy subjects. Six single nucleotide polymorphisms (SNPs) of the TNFalpha promoter at positions -1031, -863, -857, -308, -238, and -646 were analysed using automated sequencing. We compared the frequencies of alleles and genotypes in patients with BD and controls using the chi(2)-test or Fisher's exact test. Haplotype frequency was also assessed using the chi(2)-test.

RESULTS

We found no significant differences in the frequencies of polymorphic genotypes and alleles of the TNFalpha promoter region between BD patients and controls. The resulting haplotype frequencies of the BD patients were also not significantly different from those of controls. None of the TNFalpha promoter polymorphisms analysed here were associated with clinical features. Patients with the novel -646A allele of the TNFalpha promoter region were significantly associated with the expression of the HLA-B51 allele (p(corr) = 0.006), although this novel polymorphic allele was not associated with BD susceptibility.

CONCLUSION

The novel -646A TNFalpha allele was associated with the expression of HLA-B51 in Korean BD, although we found no genetic role of TNFalpha promoter polymorphisms in the susceptibility to BD. Further studies to examine the contributions of this gene polymorphism and HLA-B51 to the susceptibility to BD in large populations are required.

Autoinflammatory diseases

Autoinflammatory diseases (AIDs) are illnesses caused by primary dysfunction of the innate immune system. Proteins that are mutated in AIDs mediate the regulation of NFkappaB activation, cell apoptosis, and IL-1beta secretion through cross-regulated and sometimes common signaling pathways. AIDs include a broad number of monogenic [e.g., familial Mediterranean fever (FMF), cryopyrin-associated periodic syndrome (CAPS), mevalonate kinase deficiency (MKD), tumor necrosis factor (TNF)-receptor-associated periodic syndrome (TRAPS)] and multifactorial (e.g., Behçet's syndrome) disorders. These conditions are characterized by recurrent attacks of fever, abdominal pain, arthritis, and cutaneous signs; these symptoms sometimes overlap, obscuring diagnosis. Distinguishing signs and the use of specific functional tests where available (e.g., in MKD) are helpful. However, some patients remain hard to manage despite the advent of new genetic tests and/or due to lack of effective treatment.

HLA-B51 gene and its expression in association with Behçet’s Disease in Denizli Province of Turkey

Behçet's Disease (BD) is a multisystemic inflammatory disorder as a triad of symptoms including recurrent oral and genital aphthous ulceration, and uveitis with unknown pathogenesis. Many researchers have tried to investigate the association of HLA-B51 gene with the BD. We aimed to investigate the association of the HLA-B51 gene and its expression, also polymorphic structure by PCR, RT-PCR and sequence specific oligonucleotide primers and probes in BD patients (n: 35) and control group (n: 50). According to our results, we did not observe any association in between HLA-B51 gene, its polymorphism, expression and BD patients.

Four-digit allele genotyping of the HLA-A and HLA-B genes in Japanese patients with Behcet's disease by a PCR-SSOP-Luminex method

The present study represents the first four-digit allele genotyping of HLA-A and -B in Japanese Behcet's disease (BD) patients and controls using a new genotyping method (named the PCR-SSOP-Luminex method) to determine the association of certain HLA-A or -B alleles with BD. Peripheral blood lymphocytes were collected from 180 Japanese BD patients and 170 healthy controls. The genotype frequency of HLA-B*5101 was significantly increased in the patients (61.7%) as compared with the controls (15.9%) (Pc = 1 x 10(-16), OR = 8.5). When we recalculated the phenotype frequencies after excluding the HLA-B*51-positive patients and controls to account for the effects of the linkage disequilibrium and the abundance of the HLA-B*51 allele, the frequencies of HLA-A*2602 and HLA-B*3901 had a weak association in the patient group without HLA-B*51 as compared with the control group without HLA-B*51 (A*2602; Pc = 0.130, OR = 4.3, B*3901; Pc = 0.099, OR = 3.5). This study confirmed on the basis of using a new and more accurate genotyping method that Japanese BD patients have a strong primary association with HLA-B*5101. The significant increase of HLA-A*2602 and B*3901 in the patient group without HLA-B*51 suggests that these two alleles might also have some secondary influence on the onset of BD.

Development of an Oligochip for Genotyping Human Leukocyte Antigen-B51 and Its Clinical Application

Human leukocyte antigen (HLA) has been associated with Behcet's disease (BD), among which HLA-B51 is the most strongly associated genetic marker. The sandwich hybridization technique was applied in the design of the specific oligonucleotide probes to ensure the specific and accurate results. The probe-spotted chip was hybridized with the polymerase chain reaction (PCR) amplicons including nine suballeles (B*5101-B*5109) of exons 2 and 3 of HLA-B51 gene to determine the HLA-B51 genotypes. The results were subsequently confirmed by (PCR-SSP) and sequencing and were identical to those from polymerase chain reaction-sequencing specific primers (PCR-SSP) in 27 patients with BD and 30 healthy controls. This suggests that we successfully developed the oligochip for Behcet's-associated gene HLA-B51, which can effectively and accurately identify the HLA-B51 genotypes.

HLA class I and class II genotyping in patients with Behcet's disease: a regional study of eastern part of Turkey

Class I human leucocyte antigen (HLA)-B51 is well known to be associated with Behcet's disease in many ethnic groups. However, there has been no published paper with respect to its association with HLA class I and class II among the Turkish people who live in the eastern region of Turkey. Moreover, as it is known that B51 antigen is encoded by 21 alleles, B*5101-5121, HLA-B51 allele typing was performed, as well as HLA class I and class II genotyping of 75 patients with the disease and the 54 individuals in the matched control group. The result shows that the HLA-B51 frequency was significantly higher (58.66%) in the patient group, compared to that in the control group (18.51%) (OR = 6.245). In the subtyping of B51 alleles, 44 B51-positive patients possessed B*5101 (45.5%), B*5108 (25%), B*5105 (9.1%) and B*5104 (4.5%). There was no significant difference in the HLA-B51 allelic distribution between the patient group and the control group. However, homozygous carriers of HLA-B51 showed considerably high risk (OR = 2.647) in the patient group, compared to that in the control group. In the genotyping of class II HLA alleles, while HLA-DRB1*04 (45.3%) and HLA-DRB1*07 (24%) were the predominant alleles in the patient group, DRB1*11 (50%) appeared to be more common in the control group.

Behçet's disease

Behçet's disease is characterized by recurrent aphthous stomatitis, uveitis, genital ulcers, and skin lesions. The role of the HLA-B*51 gene has been confirmed in recent years, although its contribution to the overall genetic susceptibility to Behçet's disease was estimated to be only 19%. The production of a variety of cytokines by T cells activated with multiple antigens has been shown to play a pivotal role in the activation of neutrophils. As regards the treatment, anti-tumor necrosis factor alpha therapy has been shown to be effective for mucocutaneous symptoms as well as for sight-threatening panuveitis, although a randomized, controlled trial is required.

Mapping the HLA association in Behçet's disease: a role for tumor necrosis factor polymorphisms?

OBJECTIVE

Experimental evidence suggests that inappropriate regulation of tumor necrosis factor alpha (TNF alpha) may play a role in the pathogenesis of Behçet's disease (BD). This is supported by recent reports highlighting the efficacy of anti-TNF alpha agents in the treatment of this disease. The TNF gene is encoded in the class III region of the HLA complex adjacent to HLA-B. This genetic proximity to a gene that is already widely implicated in disease susceptibility led us to investigate the association between TNF promoter polymorphisms and susceptibility to BD.

METHODS

We studied 133 UK white Caucasoid patients with BD and 354 healthy controls. We attempted to dissect the contribution of individual polymorphisms in this gene-dense region by linkage disequilibrium mapping across 6 adjacent genes.

RESULTS

We report a novel association with the TNF promoter allele TNF-1031C. Subsequent analysis identified 2 extended HLA haplotypes associated with BD. One of them contained the previously recognized susceptibility gene HLA-B*51, while the other was defined by HLA-B*5701. Both of these haplotypes contained the TNF promoter polymorphism -1031C, an allele that was associated with disease even in individuals who did not carry either HLA-B*51 or HLA-B*5701.

CONCLUSION

The TNF-1031C allele is independently associated with susceptibility to BD in Caucasoid patients. Further studies will be required to determine the functional effects of this polymorphism, its influence in disease pathogenesis, and its role in other ethnic groups.

Expansion of gammadelta T-cells in Behçet's disease: role of disease activity and microbial flora in oral ulcers

Gammadelta T-cells participate in the immune response to infections and in autoimmunity by recognizing bacteria-derived and autologous antigens. The goal of this study was to evaluate the involvement of gammadelta T-cells in Behçet's disease (BD). Gammadelta T-cells in the peripheral-blood mononuclear cells (PBMCs) of Israeli patients with definite BD (n = 23), normal controls (n = 16), and patients with familial Mediterrranean fever (FMF; n = 20) were evaluated by means of flow cytometry. The responses of patient and control gammadelta T-cells to medium conditioned by microorganisms cultured from an oral ulcer of a patient with active BD were compared. The proportions of CD3(+) and CD8(+) cells in the PBMCs were not significantly different between groups. In contrast, gammadelta-T-cells accounted for 7.01% +/- 4.42% of the PBMCs in BD compared with 3.56% +/- 3.45% in FMF (P < .005) and 3.7% +/- 3.15% in normal individuals (P < .009). Their numbers were significantly higher during active disease than in remission (9.45% +/- 5.08% versus 2.27% +/- 3.3%; P < .009). The number of T-cell-receptor gammadelta(+) and Vdelta2(+) cells of BD patients, but not of controls, increased after 96 hours of culture in medium containing supernatant of microorganisms cultured from an oral ulcer in a patient with BD relative to their proportions in control medium: 58.2% vs 13.9% (P < .05) and 28% vs 9% (P < .04), respectively, of the cultured T-cells (n = 4).gammadelta T-cells are expanded in BD PBMCs during active disease. An exaggerated proliferative response to products released by microorganisms present in oral ulcers may play a role in this phenomenon.

Association of class I HLA antigens with the clinical manifestations of Turkish patients with Behçet's disease

Genetic factors appear to be important in the pathogenesis of Behçet's disease. Although it is known to be strongly associated with HLA-B 51, the association of HLA class I antigens with specific clinical findings of the disease has not been studied extensively and the few studies are conflicting. The aim of this study was to investigate the association of HLA class I alleles with the manifestations of Behçet's disease in Turkish patients. Eighty-five patients with Behçet's disease were typed for HLA-A, B, and C antigens with the serologic, standard microlymphocytotoxicity technique. Possible associations of the HLA complex with clinical findings of Behçet's disease were examined. Statistically significant findings are as follows (P < 0.05): increased HLA-B 51 and decreased HLA-B35 frequency in patients with thrombophlebitis, increased HLA-A29 and decreased HLA-Bw6 frequency in patients with ocular involvement, decreased HLA-Cw2 frequency in patients with erythema nodosum, and decreased HLA-Cw 7 frequency in patients with genital ulceration. Of particular note, the results of this study suggest that the presence of HLA-B 51 and the absence of HLA-B35 can be regarded as laboratory risk factors of venous thrombosis in patients with Behçet's disease.

Sequencing-based typing of HLA-B*51 alleles and the significant association of HLA-B*5101 and -B*5108 with Behçet's disease in Greek patients

Behçet's disease (BD) is widely known to be strongly associated with human leukocyte antigen (HLA) B51 in many different ethnic groups.Recently, HLA-B51 allele typing of Greek BD patients was performed to study the distribution of B*5101-B*5107 alleles in this Greek population, the B51 antigen strongly associated with BD was found to be predominantly encoded by allele B*5101. As it is now known that the B51 antigen can be encoded by 21 alleles, B*5101-B*5121, we performed HLA-B*51 allele genotyping among 58 Greek patients with BD. After serological HLA typing, typing of HLA-B*51 alleles was performed using the polymerase chain reaction-sequencing-based typing (PCR-SBT) method. The frequency of the B51 antigen was found to be significantly higher in the patient group as compared with the control group (75.9% of patients vs 22.0% of controls. In the genotyping of B51 alleles, 34 out of 44 B51-positive patients possessed B*5101, 13 out of the 44 carried B*5108. In contrast, all of the 9 B51-positive normal controls carried B*5101. This study revealed a strong association between Greeks with BD, both B*5101, B*5108, provided important insights into the molecular mechanism underlying the association between HLA status, this disease.

Allelic distribution of HLA-B*5 in HLA-B5-positive Israeli patients with Behçet's disease

In order to investigate the sub-typing of the B5 antigen in Israeli (Jewish and Arabic) patients with Behçet's disease (BD) allele-specific genotyping of B51 and B52 alleles was performed in Israeli BD patients and healthy controls. Among the HLA-B51-positive BD patients, B*5101 was found to be the predominant allele, identified in 62% of all BD patients and 78% of Jewish BD patients. HLA-B*5101 was also the predominant allele in HLA-B51-positive healthy controls. HLA-B*5108 and B*5104 alleles were identified in 23% and 15% of B51-positive BD patients, respectively. The HLA-B*5201 allele was identified in all HLA-B52-positive patients and controls. Our study suggests that both HLA-B*5101 and HLA-B*5201 are the dominant alleles of HLA-B5 in Israeli BD patients.

HLA-B*51 allele analysis by the PCR-SBT method and a strong association of HLA-B*5101 with Japanese patients with Behçet's disease

Behçet's disease (BD) is known to be associated with human leukocyte antigen (HLA) B51 in many different ethnic groups. An increased incidence of HLA-B51 in the patient group has also been reported in a Japanese population. Recently, the B51 antigen has been identified to comprise 21 alleles, B*5101-B*5121. Further, not only HLA-B*5101 but also HLA-B*5108 were found to be relatively increased in the patient groups among Italian and Saudi Arabian populations. Therefore, we performed HLA-B*51 allele genotyping by the polymerase chain reaction-sequencing based typing (PCR-SBT) method in order to investigate whether there is any correlation of one particular B51-associated allele with Japanese BD. Ninety-six Japanese patients with BD and 132 healthy Japanese volunteers were enrolled in this study. As a result, the phenotype frequency of the B51 antigen was confirmed to be remarkably increased in the patient group as compared to the ethnically matched control group (59.4% in patients vs. 13.6% in controls; Pc=0.0000000000098, R.R.=9.3). In the B*51 allele genotyping, 56 out of 57 B51-positive patients were defined as B*5101 and the remaining one was B*5102. In contrast, all of 18 B51-positive normal controls were B*5101. None of the Japanese patients and healthy controls carried the HLA-B*5108 allele. This study revealed that B*51 allelic distribution in Japanese was different from those in Italian and Saudi Arabian populations, and that the significantly high incidence of the HLA-B51 antigen in the Japanese BD patient group was mostly caused by the significant increase of the HLA-B*5101 allele.

Comparative analysis of the association of HLA-B*51 suballeles with Behçet's disease in patients of German and Turkish origin

The distribution of the different HLA-B*51 suballeles among patients with Behçet's disease (BD) of German (n=33) and Turkish (n=92) origin in comparison to their presence in the respective ethnically matched healthy control groups (German: n=325, Turkish: n=93) was studied. HLA-B*51x was significantly increased in both patient groups in comparison to the controls (Germans: 58% vs. 12%, OR 9.76, P<0.001; Turkish: 75% vs. 25%, OR 9.13, P<0.001). Molecular subtyping of B*51x revealed HLA-B*51011 and B*5108 as the predominant suballeles in both patient groups and controls although with a slightly increased frequency of HLA-B*5108 in the diseased individuals. HLA-B*5105 was the only further HLA-B*51x subtype detected in one Turkish patient heterozygous also for HLA-B*5101. HLA-B*5107 although present in a Turkish as well as German control was absent in the patient groups. There was also a tendency towards a higher degree of homozygosity for HLA-B*51x in both patient groups versus the matched controls (Germans: 10% in patients vs. 2,5% in controls; Turkish: 27% in patients vs. 13% in controls). Our study further supports previous hypothesis of an association of BD with B51 suballeles which share amino-acid residues at positions 63 and 67 as well as at positions 77-83 for specific peptide binding and natural killer (NK)-cell interactions. This applies to HLA-B*5101 and B*5108, but not to HLA-B*5107 different at position 67, which could be negatively associated with BD.

The absence of disease-specific polymorphisms within the HLA-B51 gene that is the susceptible locus for Behçet's disease

Behçet's disease is known to be associated with HLA-B51 in many different populations. Genetic evidence supports that the susceptible gene for Behçet's disease is the HLA-B51 allele at the HLA-B locus. This study was aimed to determine the HLA-B51 nucleotide sequence variation in three Behçet's disease patients and three healthy controls in order to elucidate if any disease specific mutations or polymorphisms may exist in the HLA-B51 gene of patients. Long-range polymerase chain reaction (PCR) was first carried out to give a PCR-amplified product of 9.5 kb which was then used as a template for nested PCR to give a final amplified product of 4.2 kb. This final product containing the 1.3-kb promoter/enhancer region and the entire HLA-B gene except for a 363-bp 3' terminal end segment encoding the 3' untranslated region was subcloned by the BP cloning technique and sequenced. The sequencing results showed that all the patients possessed the HLA-B*51011 allele, and there were no differences in the exonic nucleotide sequences between the three Behçet's disease patients and the three healthy controls. The HLA-B*51011 intronic and promoter/enhancer nucleotide sequences from the three patients had 22 single nucleotide polymorphisms (SNPs), a single insertion of 6 bp and a single deletion of 2 bp. On the other hand, the three healthy controls had 24 SNPs in their intronic and promoter/enhancer regions. However, none of these polymorphisms in the patients were specific for the disease. Therefore, these results clearly demonstrate that the HLA-B exonic sequence that encodes the HLA-B51 allele is the real pathogenic factor in Behçet's disease.