Identification of susceptibility SNPs in IL10 and IL23R-IL12RB2 for Behçet's disease in Han Chinese

Decoding Behcet's Uveitis: an In-depth review of pathogenesis and therapeutic advances

Behcet's disease (BD) is a rare but globally distributed vasculitis that primarily affects populations in the Mediterranean and Asian regions. Behcet's uveitis (BU) is a common manifestation of BD, occurring in over two-thirds of the patients. BU is characterized by bilateral, chronic, recurrent, non-granulomatous uveitis in association with complications such as retinal ischemia and atrophy, optic atrophy, macular ischemia, macular edema, and further neovascular complications (vitreous hemorrhage, neovascular glaucoma). Although the etiology and pathogenesis of BU remain unclear, numerous studies reveal that genetic factors (such as HLA-B51), dysregulated immune responses of both the innate and adaptive immune systems, infections (such as streptococcus), and environmental factors (such as GDP) are all involved in its development. Innate immunity, including hyperactivity of neutrophils and γδT cells and elevated NK1/NK2 ratios, has been shown to play an essential role in this disease. Adaptive immune system disturbance, including homeostatic perturbations, Th1, Th17 overaction, and Treg cell dysfunction, is thought to be involved in BU pathogenesis. Treatment of BU requires a tailored approach based on the location, severity of inflammation, and systemic manifestations. The therapy aims to achieve rapid inflammation suppression, preservation of vision, and prevention of recurrence. Systemic corticosteroids combined with other immunosuppressive agents have been widely used to treat BU, and beneficial effects are observed in most patients. Recently, biologics have been shown to be effective in treating refractory BU cases. Novel therapeutic targets for treating BU include the LCK gene, Th17/Treg balance, JAK pathway inhibition, and cytokines such as IL-17 and RORγt. This article summarizes the recent studies on BU, especially in terms of pathogenesis, diagnostic criteria and classification, auxiliary examination, and treatment options. A better understanding of the significance of microbiome composition, genetic basis, and persistent immune mechanisms, as well as advancements in identifying new biomarkers and implementing objective quantitative detection of BU, may greatly contribute to improving the adequate management of BU patients.

Association of IL-23R and IL-10 variations with Behçet disease: a genetic analysis study

Behçet disease (BD) is an autoimmune and autoinflammatory disease mainly affecting the Silk Road countries. The interindividual severity of BD depends on differences in the polymorphic profiles of the patients. One of the most prominent markers, HLA-B51 positivity, is also observed in 40-60% of patients with BD on the Silk Road. Inflammatory markers such as interleukin 10 (IL-10) and interleukin 23 receptor (IL-23R) are also widely associated with BD etiology. The polymorphisms on these genes may change the susceptibility to BD. In this case-control study, we assessed the associations of IL-10 rs3024498 and IL-23R rs10889677 single-nucleotide polymorphisms (SNPs) with BD susceptibility, if any. Two hundred eighty HLA-B51-positive patients with BD and 300 healthy controls were genotyped for these SNPs using RFLP-PCR. The chi-square test was used for genotyping. We found that IL-23R rs10889677 CC and IL-10 rs3024498 CT genotype frequencies were higher in the BD group than in the control group (p < 0.0001 and p = 0.0293, respectively). The recessive model (AA + CC vs. AC) and combined genotype (AC + CT) results were also statistically significant (p < 0.0001 and p = 0.0364, respectively). We conclude that IL-23R rs10889677 and IL-10 rs3024498 SNPs may be associated with the susceptibility to BD.

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

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

γδ T cells in autoimmune uveitis pathogenesis: A promising therapeutic target

Autoimmune uveitis is a non-infectious, inflammatory intraocular disease that affects the uveal and adjacent tissues. It frequently causes varying degrees of visual loss. Evidence for the strong association between activated γδ T cells and the development of autoimmune uveitis is growing. The innate and adaptive immune response are connected in the early phases by the γδ T cells that contain the γ and δ chains. γδ T cells can identify antigens in a manner that is not constrained by the MHC. When activated by various pathways, γδ T cells can not only secrete pro-inflammatory factors early on (such as IL-17), but they can also promote Th17 cells responses, which ultimately exacerbates autoimmune uveitis. Therefore, we review the mechanisms by which γδ T cells affect autoimmune uveitis in different activation and disease states. Moreover, we also prospect for immunotherapies targeting different γδ T cell-related action pathways, providing a reference for exploring new drug for the treatment of autoimmune uveitis.

Genetics in Behcet's Disease: An Update Review

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

A genome-wide association study in Chinese identifies novel risk loci for Behcet's uveitis

PURPOSE

To explore susceptibility loci associated with uveitis in Behcet's disease (BD).

METHODS

We conducted a genome-wide association study (GWAS) primarily involving 978 BD uveitis cases and 4388 controls and a replication study of 953 BD uveitis cases and 2129 controls in the Chinese population. Luciferase reporter analysis and Chromatin immunoprecipitation (ChIP) assay were performed to explore the functional role of susceptibility genetic variants nearby ZMIZ1.

RESULTS

Three independent HLA alleles (HLA-B51, HLA-A26 and HLA-C0704) were identified in a genome-wide association with BD uveitis. In the non-HLA region, besides confirming 7 previously reported loci, we identified 22 novel susceptibility variants located in 16 loci. Meta-analysis of the Chinese cohort involving 1931 cases and 6517 controls and a published Japanese cohort of 611 cases and 737 controls showed genome-wide significant associations with ZMIZ1, RPS6KA4, IL10RA, SIPA1-FIBP-FOSL1 and VAMP1. Functional experiments demonstrated that genetic variants of ZMIZ1 were associated with an enhanced transcriptional activity and an increased expression of ZMIZ1.

CONCLUSIONS

This GWAS study identified a novel set of genetic variants that are associated with susceptibility to uveitis in BD. These findings enriched our understanding of the contribution of genetic factors to the disease.

SNP-mediated binding of TBX1 to the enhancer element of IL-10 reduces the risk of Behçet's disease

Aims: The genetic association between Behçet's disease susceptibility and IL-10 has been confirmed in multiple cohorts, but the underlying mechanism of this association remains unclear. Materials & methods: We combined public resources and laboratory experiments (electrophoretic mobility shift assays, chromatin immunoprecipitation, luciferase reporter gene and CRISPR/Cas9 genome editing) to analyze transcription factor binding and enhancer activity controlling IL-10 expression. Results & conclusion: The T allele of noncoding rs3024490 within super-enhancer elements is able to specifically bind TBX1 and, in turn, promotes the enhancer activity and increased expression of IL-10. However, a relative deficiency in TBX1 in Behçet's disease patients leads to the low expression of IL-10 and increased risk of developing Behçet's disease.

A Darwinian View of Behçet's Disease

Behçet's disease (BD) is a multisystem inflammatory disorder of unknown etiology, characterized by oral and genital ulceration, with other complications including eye, skin, joint, and central nervous system (CNS) lesions. Diagnosis is based on clinical findings, which may differ between patients. There is a strong genetic basis for BD; however, only a few genes have been associated with the disease across the geographical spread of BD. In this article, we discuss the history and combination of genes involved in this complex disease in relation to the geographical range and present our view that the disease has developed from a Darwinian perspective, with different gene polymorphisms that affect the same biological pathway. Moreover, these mutations individually are protective mechanisms against the disease relevant to each region, which affected both archaic and modern humans.

Behçet's Disease-Do Microbiomes and Genetics Collaborate in Pathogenesis?

Behçet’s disease (BD) is a multisystem autoinflammatory condition characterized by mucosal ulceration, breakdown of immune privilege sites and vasculitis. A genetic basis for BD has been described in genome-wide and validation studies. Similarly, dysbiosis of oral and gut microbiomes have been associated with BD. This review will describe links between genetic polymorphisms in genes encoding molecules involved in gut biology and changes seen in microbiome studies. A potential decrease in bacterial species producing short chain fatty acids linked to mutations in genes involved in their production suggests a potential therapy for BD.

Association between Interleukin-10 Gene Polymorphisms and Behcet's Disease Susceptibility: Evidence from a Meta-Analysis

Epidemiological studies have demonstrated that interleukin-10 (IL-10) polymorphisms may be associated with the development of Behcet's disease (BD). However, the published results were inconsistent. Therefore, this meta-analysis was conducted to derive a more precise relationship between IL-10 polymorphisms and BD susceptibility. Online databases (PubMed, Embase, Science Citation Index (SCI), CNKI, and WanFang) were searched to identify eligible studies. Odds ratio (OR) and a 95% confidence interval (CI) were applied to assess the relationship strength between IL-10 -1082A>G (rs1800896), -819T>C (rs1800871), and -592A>C (rs1800872) polymorphisms and BD susceptibility. Publication bias, sensitivity, and cumulative analyses were conducted to measure the robustness of our findings. Finally, fifteen articles (36 independent case-control studies) involving 5,971 patients and 8,913 controls were included. Overall, significant associations between -819T>C polymorphisms and BD risk were observed in the total population (C vs. T: OR = 0.72, 95%CI = 0.67-0.77, P < 0.01, I 2 = 36.6%; TC vs. TT: OR = 0.73, 95%CI = 0.66-0.80, P < 0.01, I 2 = 23.0%; CC vs. TT: OR = 0.52, 95%CI = 0.39-0.70, P < 0.01, I 2 = 53.7%; TC+CC vs. TT: OR = 0.67, 95%CI = 0.61-0.71, P < 0.01, I 2 = 22.1%; and CC vs. TT+TC: OR = 0.66, 95%CI = 0.53-0.82, P < 0.01, I 2 = 57.8%). Moreover, the IL-10 -592 A>C polymorphism and the ACC haplotype exhibited a significant, protective effect against BD susceptibility. In summary, our meta-analysis suggested that IL-10 gene polymorphisms may play a salient role for BD development.

Activation of the interleukin-23/interleukin-17 signalling pathway in autoinflammatory and autoimmune uveitis

Uveitis is a group of diseases characterized by intraocular inflammation, of which some are driven by autoinflammatory or autoimmune responses, such as Vogt-Koyanagi-Harada disease, Behçet's disease, uveitis associated with spondyloarthritis, ocular sarcoidosis, sympathetic ophthalmia and birdshot chorioretinopathy. These entities have various clinical forms, but genetic and biomarker data suggest that they share a common molecular basis, activation of the Interleukin (IL)-23/IL-17 pathway. Multiple factors including genetic predisposition, various cytokine imbalances, infectious agents and gut alterations are found to trigger an aberrant response of this pathway. The enhanced activity of the IL-23/IL-17 pathway is committed to the expansion and pathogenicity of Th17 cells. Evidence from animal models demonstrates that the development of pathogenic Th17 cells is responsible for the induction of experimental autoimmune uveitis. Further findings indicate that retinal pigment epithelium (RPE) cells may be a target of IL-17. IL-17 triggers downstream inflammatory cascades and causes dysfunction of RPE cells, which may affect retinal barrier function and thereby promote intraocular inflammation. Currently, several emerging drugs blocking the IL-23/IL-17 pathway have been assessed for the treatment of uveitis in pilot studies. The purpose of this is to summarize updated biological knowledge and preliminary clinical data, providing the rationale for further development and evaluation of novel drugs targeting the IL-23/IL-17 pathway in autoinflammatory and autoimmune uveitis. Future studies may focus on translational medicine targeting the IL-23/IL-17 pathway for the improvement of diagnosis and treatment of uveitis. In conclusion, activation of the IL-23/IL-17 pathway is a critical biological event and can be an important target for the treatment of autoinflammatory and autoimmune uveitis.

Epigenome-wide association study identifies Behçet's disease-associated methylation loci in Han Chinese

OBJECTIVE

The aetiology of Behçet's disease (BD), known as a systemic vasculitis, is not completely understood. Increasing evidence suggests that aberrant DNA methylation may contribute to the pathogenesis of BD. The aim of this epigenome-wide association study was to identify BD-associated methylation loci in Han Chinese.

METHODS

Genome-wide DNA methylation profiles were compared between 60 BD patients and 60 healthy controls using the Infinium Human Methylation 450 K Beadchip. BD-associated methylation loci were validated in 100 BD patients and 100 healthy controls by pyrosequencing. Gene expression and cytokine production was quantified by real-time PCR and ELISA.

RESULTS

A total of 4332 differentially methylated CpG sites were associated with BD. Five differentially methylated CpG sites (cg03546163, cg25114611, cg20228731, cg23261343 and cg14290576) revealed a significant hypomethylation status across four different genes (FKBP5, FLJ43663, RUNX2 and NFIL3) and were validated by pyrosequencing. Validation results showed that the most significant locus was located in the 5'UTR of FKBP5 (cg03546163, P = 3.81E-13). Four CpG sites with an aberrant methylation status, including cg03546163, cg25114611, cg23261343 and cg14290576, may serve as a diagnostic marker for BD (area under the receiver operating curve curve = 83.95%, 95% CI 78.20, 89.70%). A significantly inverse correlation was found between the degree of methylation at cg03546163 as well as cg25114611 and FKBP5 mRNA expression. Treatment with a demethylation agent, 5-Aza-2'-deoxycytidine resulted in an increase of FKBP5 mRNA expression and a stimulated IL-1β production.

CONCLUSION

Our findings suggest that aberrant DNA methylation, independently of previously known genetic variants, plays a vital role in the pathogenesis of BD.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, chictr.org.cn, ChiCTR-CCC-12002184.

Variant in ERAP1 promoter region is associated with low expression in a patient with a Behçet-like MHC-I-opathy

Behçet disease (BD) is an immune-mediated disease. The cause of BD remains unknown, but the existence of multiple pathological pathways is suspected, including different genetic factors. Polymorphisms in ERAP1 gene have been associated with an increased risk of BD. However, while current BD-associated ERAP1 variants are suggested to contribute to disease by altering the activity of the encoded protein, there is no knowledge of variants that alter the expression level of ERAP1, despite previous associations between ERAP1 expression and BD. Here, we used whole-exome sequencing of a patient with a Behçet-like MHC-I-opathy to identify that the patient, unlike its healthy parents, was homozygous for a rare 1-bp deletion, rs140416843, in the promoter region of ERAP1. rs140416843 has not previously been associated with disease, but is linked to ERAP1 haplotype Hap10 which is associated with BD. The expression of ERAP1 by both RT-qPCR and RNA sequencing showed that ERAP1 mRNA expression correlated with the zygosity for the identified deletion and was decreased in comparison to a healthy cohort. In conclusion, we diagnosed the patient as having BD, and hypothesize that rs140416843-mediated changes in ERAP1 expression play a causative role in BD and that this risk factor is contributing to the association between Hap10 and BD. This is the first report to identify a variant that may cause BD by altering the expression of ERAP1, and our findings suggest that downregulation of ERAP1 expression can serve as a diagnostic marker for BD.

Exploring the association of IL-10 polymorphisms in Behcet's disease: a systematic review and meta-analysis

Background

Polymorphisms in the interleukin-10 (IL-10) gene have been studied in various ethnic groups for possible association with Behçet’s disease (BD). This study aimed to perform a meta-analysis of eligible studies to calculate the association of IL-10 polymorphisms with BD.

A systematic literature search was carried out in PubMed, Embase, Web of Science, and Scopus databases to identify relevant publications, and extracted the respective results. Pooled odds ratio (OR) with 95% confidence interval (CI) was used to evaluate the power of association with a random-effects model.

Results

A total of 19 articles, consisting of 10,626 patients and 13,592 controls were included in the meta-analysis. The meta-analysis revealed significant associations in allelic and genotypic test models of − 819 (C vs. T: OR = 0.691, P < 0.001; CC vs. TT: OR = 0.466, P < 0.001; CC + CT vs. TT: OR = 0.692, P < 0.001; and CC vs. CT + TT: OR = 0.557, P < 0.001), − 592 (C vs. A: OR = 0.779, P = 0.002; CC + AA vs. AA: OR = 0.713, P = 0.021; and CA vs. AA: OR = 0.716, P = 0.016), rs1518111 (G vs. A: OR = 0.738, P < 0.001; GG vs. AA: OR = 0.570, P < 0.001; GG + AG vs. AA: OR = 0.697, P < 0.001; GG vs. GA + AA: OR = 0.701, P < 0.001; and AG vs. GG: OR = 0.786, P = 0.004) and rs1554286 (C vs. T: OR = 0.582, P < 0.001; CC vs. TT: OR = 0.508, P < 0.001; CC + CT vs. TT: OR = 0.605, P < 0.001; CC vs. CT + TT: OR = 0.665, P = 0.012; and CT vs. TT: OR = 0.646, P = 0.001). However, we failed to find any association between − 1082 polymorphism and susceptibility of BD.

Conclusion

This meta-analysis demonstrated that the interleukin-10 -819, − 596, rs1518111 and rs1554286 polymorphisms could be responsible against BD susceptibility, and should probably be regarded as a protective factor for Behçet’s disease.

Current State of Precision Medicine in Primary Systemic Vasculitides

Precision medicine (PM) is an emerging data-driven health care approach that integrates phenotypic, genomic, epigenetic, and environmental factors unique to an individual. The goal of PM is to facilitate diagnosis, predict effective therapy, and avoid adverse reactions specific for each patient. The forefront of PM is in oncology; nonetheless, it is developing in other fields of medicine, including rheumatology. Recent studies on elucidating the genetic architecture of polygenic and monogenic rheumatological diseases have made PM possible by enabling physicians to customize medical treatment through the incorporation of clinical features and genetic data. For complex inflammatory disorders, the prevailing paradigm is that disease susceptibility is due to additive effects of common reduced-penetrance gene variants and environmental factors. Efforts have been made to calculate cumulative genetic risk score (GRS) and to relate specific susceptibility alleles for use of target therapies. The discovery of rare patients with single-gene high-penetrance mutations informed our understanding of pathways driving systemic inflammation. Here, we review the advances in practicing PM in patients with primary systemic vasculitides (PSVs). We summarize recent genetic studies and discuss current knowledge on the contribution of epigenetic factors and extracellular vesicles (EVs) in disease progression and treatment response. Implementation of PM in PSVs is a developing field that will require analysis of a large cohort of patients to validate data from genomics, transcriptomics, metabolomics, proteomics, and epigenomics studies for accurate disease profiling. This multi-omics approach to study disease pathogeneses should ultimately provide a powerful tool for stratification of patients to receive tailored optimal therapies and for monitoring their disease activity.

The associations between interleukin 10 polymorphisms and susceptibility to autoimmune uveitis - a meta-analysis

Autoimmune uveitis is an ocular inflammatory disease that is associated with genetic factors. Interleukin 10 (IL-10) is an immune-regulatory cytokine of autoimmune diseases. IL-10 is considered a candidate gene for uveitis. We evaluate the association of IL-10 with susceptibility to autoimmune uveitis. The results from seven studies were pooled in the meta-analysis, covering a total of 2893 cases of uveitis and 4873 controls. Published literature from MEDLINE and Embase was retrieved. Meta-analyses were conducted on the associations between autoimmune uveitis and the -1082 A/G and -819 C/T polymorphisms of the IL-10 gene. The meta-analysis revealed no association between uveitis and the IL-10 -1082 A allele (OR = 0.91, 95% CI = 0.64-1.30, p = 0.62). The recessive, dominant, and homozygous models of the IL-10 -1082 A/G allele also suggested no association between autoimmune uveitis and each genotype. The meta-analysis revealed significant association between uveitis and the -892 C allele (OR = 0.81, 95% CI = 0.67-0.98, p = 0.03). In addition, significant association was found in homozygous models (OR = 0.58, 95% CI = 0.36-0.92, p = 0.02). However, the dominant and recessive models of the IL-10 -819 C/T polymorphisms showed no association between uveitis and each genotype. This meta-analysis showed that the -1082 A/G polymorphisms of IL-10 were not associated with autoimmune uveitis, but the -819 C/T polymorphisms were significantly associated with uveitis.

Behçet's disease: An immunogenetic perspective

Behçet's disease (BD) is a chronic and rare multisystemic disorder defined by autoimmunity and inflammatory characteristics, manifested by ocular lesions, recurrent genital and oral ulcers, skin symptoms and arthritis as well as neurological, intestinal, and vascular involvement. Despite the unknown cause of BD, there is some strong documentation for immunological, genetic, environmental, and infectious factors playing a role in the pathogenesis of BD. While the nature of the genetic variants remains unidentified, many genetic risk factors are considered to contribute to BD susceptibility. Along with human leukocyte antigen gene encoding B*51 (HLA-B*51) and areas including the major histocompatibility complex class I, genome-wide association studies have recognized numerous other BD susceptibility genes including those encoding interleukin (IL)-10, IL-12 receptor β 2 (IL-12RB2), IL-23 receptor (IL-23R), C-C chemokine receptor 1 gene, signal transducer and activator of transcription 4 (STAT4), endoplasmic reticulum aminopeptidase (ERAP1), and genes encoding killer cell lectin-like receptor family members (KLRC4-KLRK1). It is believed that BD could be considered as a disorder lying in between autoimmune and autoinflammatory syndromes. The positive responses to classical immunosuppressive agents like azathioprine and cyclosporine and involvement of autoantigens in the initiation of the disorder are the main BD features that reflect the autoimmune nature of the disorder. In this review, we address recent findings on the role of common cytokines, antibodies and immunogenetic factors in BD.

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

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

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

Background

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

Objective

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

Methods

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

Results

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

Conclusions

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

Single-Nucleotide Polymorphisms in IL23R-IL12RB2 (rs1495965) Are Highly Prevalent in Patients with Behcet's Uveitis and Vary Between Populations

Purpose: To test the frequency of single-nucleotide polymorphisms in the IL-10, IL23R-IL12RB2 genes in patients with Behcet's uveitis. Methods: Blood samples were collected from 89 Israeli and Turkish patients, and from healthy control subjects of different origins. Genomic DNA was extracted from peripheral blood leukocytes and genotyped. Results: The risk allele, A, in rs1800871, of IL-10 gene was highly prevalent in Behcet's uveitis and healthy control samples alike; highest among the Turkish groups. Prevalence of G allele, in rs1495965, in the IL23R-IL12RB2 gene was high in Behcet's uveitis patients, and among healthy Turkish and Israelis of Middle Eastern origin, while lower among the other Israeli control group (77.9%, 78.9%, 27.8%, respectively, P < 0.001). Conclusion: Our findings highlight the differences between populations and may account for the increased prevalence of the disease among Turkish and Israelis of Middle Eastern origin. Further studies are required to map other healthy and affected populations.

Association of genetic variations in PTPN2 and CD122 with ocular Behcet's disease

BACKGROUND

Protein tyrosine phosphatases (PTPs) play critical roles in human autoimmunity. Previous studies found that PTPN2 may be the key regulatory factor in the T-cell-mediated immune response. PTPN2 regulates the Janus kinase/signal transducers and activators of transcription pathway by inhibiting signalling via the interleukin (IL)-2 receptor (CD122). An association between genetic variations in PTPN2 and CD122 with ocular Behcet's disease (BD) has not yet been addressed and was therefore the purpose of this study.

METHODS

A two-stage case-control study was performed in 906 patients with ocular BD and 2178 healthy controls. Genotyping analysis of 11 single nucleotide polymorphisms was carried out. The expression of PTPN2 in peripheral blood mononuclear cells (PBMCs) was quantified by real-time PCR and cytokine production was measured by ELISA.

RESULTS

The frequency of the GG genotype of PTPN2-rs7234029 was significantly lower in patients with ocular BD (p=1.94×10^-5, p_c=8.34×10^-4, OR=0.466). Stratification according to gender showed that rs7234029 was significantly associated with BD in men. A stratified analysis according to the main clinical features showed that rs7234029 was significantly associated with genital ulcers, skin lesions and a positive pathergy test. No association could be detected between BD and CD122 gene polymorphisms. Functional studies showed that rs7234029 GG genotype carriers had a higher PNPT2 mRNA expression level than those which carrying the AA or AG genotype, and a decreased secretion of IL-17 and tumour necrosis factor-alpha was seen by PBMCs from GG carriers. No significant difference could be detected concerning IL-1β or IL-6 production by stimulated PBMCs between the different genotype groups.

CONCLUSIONS

This study shows that a PTPN2-rs7234029 polymorphism is associated with ocular BD and is strongly influenced by gender. In addition, our results suggest that the genetic association with PTPN2 may involve the regulation of PTPN2 mRNA expression and cytokine secretion.

Behçet's disease risk association fine-mapped on the IL23R-IL12RB2 intergenic region in Koreans

Background

Behçet’s disease (BD) susceptibility had been associated with single-nucleotide polymorphisms (SNPs) in IL23R–IL12RB2, IL10, STAT4, or ERAP1 locus in Japanese, Turkish, Chinese, and other populations, but not in a Korean genome-wide association study (GWAS). We aimed to fine-map BD risk association of these four loci using extensive imputation and additional genotyping for replication.

Methods

In the discovery phase, 369 patients with BD enrolled in the previous Korean GWAS and 2000 controls retrieved from a population-based cohort of healthy Koreans were imputed for their genotypes of all SNPs in the four loci using the Asian data of the 1000 Genomes Project as reference. For genotype imputation of ERAP1 SNPs, the adjacent ERAP2 SNPs were also covered. For the 10 most significantly associated SNPs (8 imputed and 2 GWAS-genotyped), an additional 84 patients with BD and 283 healthy controls were genotyped for replication. The results from the discovery and replication phases were pooled for meta-analysis using the Mantel-Haenszel test to estimate the odds ratio (OR) and 95% confidence interval (CI).

Results

An IL23R–IL12RB2 intergenic SNP rs1495965 was significantly associated with BD risk (OR (95% CI) = 1.5 (1.3, 1.7), P = 2.5 × 10⁻⁷) in the pooled meta-analysis of the discovery (1.4 (1.2, 1.7), P = 4.9 × 10⁻⁷) and replication (1.9 (1.3, 2.6), P = 6.0 × 10⁻⁴) phases. BD risk association was fine-mapped on the intergenic region rather than the two flanking genes, as rs1495966 and rs4655535, almost perfectly correlated with rs1495965 (r² = 0.99), were also located in the same intergenic region. Consistent with previous reports, the P values tended to be lower within IL23R than IL12RB2. On the other hand, several IL10 SNPs were suggested for association in the discovery phase but all failed in the replication phase. No SNP in ERAP1–ERAP2 and STAT4 was suggested even in the discovery phase.

Conclusions

BD susceptibility association was fine-mapped on the intergenic region between IL23R and IL12RB2 as marked by three correlated SNPs, rs1495965, rs1495966, and rs4655535.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1435-5) contains supplementary material, which is available to authorized users.

Genetic polymorphisms of C-type lectin receptors in Behcet's disease in a Chinese Han population

C-type lectin receptors (CLRs) have been demonstrated to be involved in several autoimmune diseases. The role of CLRs in Behcet’s disease (BD) is unknown and thus was the purpose of this study. A two-stage association study was carried out and a total of 766 BD patients and 1674 healthy controls were recruited. Genotyping of 14 SNPs of 13 genes in CLRs was carried out by iPLEX Gold genotyping or polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. The expression of mannose binding lectin 2 (MBL2) and killer cell lectin like receptor C4 (KLRC4) was measured by Real-time PCR. Significantly increased frequencies of the A allele as well as AA genotype of rs1800450 in MBL2 (Pc = 2.50 × 10⁻⁶, OR = 1.494; Pc = 2.24 × 10⁻⁶,OR = 2.899; respectively) and TT genotype of rs2617170 in KLRC4 (Pc = 2.53 × 10⁻⁶, OR = 1.695) and decreased frequencies of GG genotype of rs1800450 (Pc = 1.56 × 10−3, OR = 0.689) and C allele as well as CC genotype of rs2617170 (Pc = 2.05 × 10−9,OR = 0.664; Pc = 1.20 × 10−5, OR = 0.585; respectively) were observed in BD. Two variants, p.Gly54Asp (rs1800450) and p.Asn104Ser (rs2617170) affect MBL2 and KLRC4 protein stability and expression. Our study demonstrates that the MBL2/rs1800450 and KLRC4/rs2617170 are susceptibility factors for BD in a Chinese Han population.

The Association of Chemokine Gene Polymorphisms with VKH and Behcet's Disease in a Chinese Han Population

To investigate the association of chemokine gene polymorphisms and Behcet's disease (BD) and Vogt Koyanagi Harada (VKH) disease in a Chinese Han population. A case-control study was performed. Three hundred and seventy-one BD patients, 371 VKH disease patients, and 605 healthy controls were recruited to determine genetic variants of 26 SNPs in 12 chemokine genes with iPLEX Gold genotyping assay and Sequenom MassARRAY or TaqMan SNP assays. In this study, P_uncorr values showed a weak association of five SNPs of five genes in BD and three SNPs of three genes in VKH disease. However, after Bonferroni correction, the 26 investigated SNPs showed no significant differences in genetic variants, including genotype and allele frequencies, between BD or VKH disease patients and healthy individuals. Haplotype analysis for the chemokine genes showed a significant association with the TC haplotype of CXCL12 in VKH. Stratified gender analysis and genotype-phenotype analysis were conducted to analyze the association of the 26 SNPs of 12 chemokine genes with BD and VKH disease. However, no significant association was observed after Bonferroni correction. This study showed no association of 26 SNPs in 12 chemokine genes with both BD and VKH disease in a Chinese Han population.

Ocular Behcet's disease is associated with aberrant methylation of interferon regulatory factor 8 (IRF8) in monocyte-derived dendritic cells

Aberrant methylation of interferon regulatory factor 8 (IRF8) has been noted in various tumors. IRF8 has also been reported to be involved in many autoimmune diseases, including Behcet's disease (BD). However, the methylation status of IRF8 in BD has not been reported. To address this issue, we investigated whether the degree of methylation of IRF8 in dendritic cells (DCs) plays a role in the development of BD. We found a lower mRNA expression and a higher methylation level of IRF8 in active ocular BD patients as compared to normal subjects and inactive patients. Treatment with a demethylation agent, 5-Aza-2'-deoxycytidine (DAC) resulted in an increase of mRNA expression and a reduction of the IRF8 methylation level. It also down-regulated the expression of the co-stimulatory molecules CD86, CD80, CD40, and reduced the production of IL-6, IL-1β, IL-23 and IL-12. An inhibition of Th1/Th17 responses was observed as evidenced by a decreased production of IFN-γ, IL-17, and a reduction of IFN-γ/IL-17- producing CD4⁺ T cells following treatment with DAC. This study shows that active ocular BD patients have an aberrant IRF8 methylation status. These findings suggest that epigenetic control of IRF8 expression may offer a future target in the treatment of ocular BD.

Genetic analysis of innate immunity in Behcet's disease identifies an association with IL-37 and IL-18RAP

Interleukin-1 (IL-1) and the IL-1 receptor (IL-1R) family play an important role in the pathogenesis of inflammatory diseases. This study aimed to investigate the association between single nucleotide polymorphisms (SNP) of IL-1 and IL-1R family genes with Vogt-Koyanagi-Harada (VKH) and Behcet’s disease (BD) in Han Chinese. The case-control study was divided into two stages and included 419 VKH cases, 1063 BD cases and 1872 healthy controls. The MassARRAY platform (Sequenom), iPLEX Gold Assay and TaqMan SNP assays were used to score genotypes of 24 SNPs. The expression of IL-37 and IL-18Rap was measured by ELISA and real-time PCR in genotyped healthy individuals. A significantly lower frequency of the AG genotype, and a higher frequency of the GG genotype and G allele of IL-37/rs3811047 were observed in BD as compared to controls. AA genotype and A allele frequency of IL-18RAP/rs2058660 was significantly decreased in BD as compared to controls. Functional studies performed in healthy controls showed that rs3811047 AG genotype carriers had a higher IL-37 gene expression in peripheral blood mononuclear cells (PBMCs) than GG carriers. GG carriers showed a higher cytokine expression as compared to AG carriers. No association was detected between the tested SNPs and VKH.