Comprehensive analysis of HLA genes in Takayasu arteritis in Japan

Anti-integrin αvβ6 antibody in Takayasu arteritis patients with or without ulcerative colitis

Background

It has been well documented that Takayasu arteritis (TAK) and ulcerative colitis (UC) coexist in the same patients. HLA-B*52 characterizes the co-occurrence, which is one of the common genetic features between these two diseases, indicating shared underlying pathologic mechanisms. Anti-integrin αvβ6 antibody (Ab) is present in sera of UC patients in a highly specific manner. We investigated if there were any associations between anti-integrin αvβ6 Ab and TAK, considering the risk HLA alleles.

Methods

A total of 227 Japanese TAK patients were recruited in the current study and their serum samples were subjected to measurement of anti-integrin αvβ6 Ab by ELISA. The clinical information, including the co-occurrence of UC, was collected. The HLA allele carrier status was determined by Luminex or genotype imputation.

Results

The information about the presence of UC was available for 165 patients, among which eight (4.84%) patients had UC. Anti-integrin αvβ6 antibody was identified in 7 out of 8 TAK subjects with UC (87.5%) while only 5 out of 157 (3.18%) TAK subjects without UC had the antibody (OR 121, p=7.46×10-8). A total of 99 out of 218 (45.4%) patients were HLA-B*52 carriers. There was no significant association between the presence of anti-integrin αvβ6 Ab and HLA-B*52 carrier status in those without UC (OR 2.01, 95% CI 0.33-12.4, p = 0.189).

Conclusions

The prevalence of anti-integrin αvβ6 Ab was high in TAK patients with UC, but not in the absence of concomitant UC. The effect of HLA-B*52 on anti-integrin αvβ6 Ab production would be minimal.

Aortitis after switching short-acting granulocyte colony-stimulating factors in a lymphoma patient with HLA-B52

Aortitis is a rare adverse event of granulocyte colony-stimulating factor (G-CSF) treatment. Several previous studies have described recurrent aortitis caused by re-administration of the same G-CSF. However, no previous studies have examined the safety of switching between short-acting G-CSFs in patients who develop aortitis. We report the case of a 55-year-old man with refractory diffuse large B-cell lymphoma, who developed G-CSF-associated aortitis. The aortitis was triggered by filgrastim and recurred after treatment with lenograstim. The patient possessed human leukocyte antigen B52, which has been implicated in Takayasu arteritis. In addition, a drug-induced lymphocyte stimulation test for lenograstim performed upon detection of recurrent G-CSF-associated aortitis produced a positive result. Our case suggests that switching from one short-acting G-CSF to another does not prevent recurrence of G-CSF-associated aortitis. Although the etiology of G-CSF-associated aortitis has not been fully elucidated, our case also suggests that some patients may be genetically predisposed to aortitis.

Common Risk Variants in AHI1 Are Associated With Childhood Steroid Sensitive Nephrotic Syndrome

Introduction

Steroid-sensitive nephrotic syndrome (SSNS) is the most common form of kidney disease in children worldwide. Genome-wide association studies (GWAS) have demonstrated the association of SSNS with genetic variation at HLA-DQ/DR and have identified several non-HLA loci that aid in further understanding of disease pathophysiology. We sought to identify additional genetic loci associated with SSNS in children of Sri Lankan and European ancestry.

Methods

We conducted a GWAS in a cohort of Sri Lankan individuals comprising 420 pediatric patients with SSNS and 2339 genetic ancestry matched controls obtained from the UK Biobank. We then performed a transethnic meta-analysis with a previously reported European cohort of 422 pediatric patients and 5642 controls.

Results

Our GWAS confirmed the previously reported association of SSNS with HLA-DR/DQ (rs9271602, P = 1.12 × 10-27, odds ratio [OR] = 2.75). Transethnic meta-analysis replicated these findings and identified a novel association at AHI1 (rs2746432, P = 2.79 × 10-8, OR = 1.37), which was also replicated in an independent South Asian cohort. AHI1 is implicated in ciliary protein transport and immune dysregulation, with rare variation in this gene contributing to Joubert syndrome type 3.

Conclusions

Common variation in AHI1 confers risk of the development of SSNS in both Sri Lankan and European populations. The association with common variation in AHI1 further supports the role of immune dysregulation in the pathogenesis of SSNS and demonstrates that variation across the allele frequency spectrum in a gene can contribute to disparate monogenic and polygenic diseases.

Advances in Takayasu arteritis: An Asia Pacific perspective

Takayasu Arteritis (TA) is a rare form of chronic granulomatous large vessel vasculitis that is more common in Asia compared to other parts of the world. There have been several developments in the field of Takayasu arteritis in relation to genetics, classification, clinical features, imaging, disease activity assessment and management and much of these works have been done in the Asia Pacific region. We will be discussing selected few in the current review.

HLA-B52 allele in giant cell arteritis may indicate diffuse large-vessel vasculitis formation: a retrospective study

Background

This study aimed to identify new characteristics of elderly onset large-vessel vasculitis (EOLVV) by focusing on human leucocyte antigen (HLA) genotype, polymyalgia rheumatica (PMR), and affected vascular lesions observed on positron emission tomography/computed tomography (PET/CT) imaging.

Methods

We retrospectively studied 65 consecutive Japanese patients with large-vessel vasculitis (LVV) who had extracranial vasculitis lesions and underwent PET/CT imaging. PET/CT images were assessed using the semi-quantitative PET visual score of each affected vessel, and the PET vascular activity score (PETVAS) and number of affected vessels were calculated. Subjects were subsequently grouped based on age at onset, superficial temporal artery (STA) involvement, and presence of PMR and compared each group according to HLA genotype. Unsupervised hierarchical cluster analysis was used to identify the patients with similar characteristics in terms of affected vascular lesions detected through PET/CT imaging. The clinical characteristics and PET/CT findings of the population newly identified in this study were examined.

Results

Twenty-seven patients with EOLVV did not meet the American College of Rheumatology 1990 criteria for giant cell arteritis (GCA) and Takayasu arteritis and were considered as unclassified EOLVV (UEOLVV). The unsupervised hierarchical cluster analysis revealed that UEOLVV with PMR and large-vessel GCA (LV-GCA) formed a cluster of LVV with GCA features (i.e., PMR and/or STA involvement) when restricted to patients who were HLA-B52-positive. Patients who were HLA-B52-positive with LVV and GCA features had similar clinical characteristics and patterns of affected vessels and presented with diffuse LVV lesions. HLA-B52-positive patients who had LVV with GCA features also presented with higher PETVAS, more affected vessels, and lower rates of biologics usage and relapse compared to HLA-B52-positive patients with TAK.

Conclusions

Patients who had UEOLVV with PMR had similar characteristics to patients with LV-GCA. Patients who were HLA-B52-positive and had LVV with GCA features presented with diffuse vascular lesions and may comprise a core population of Japanese patients with EOLVV. The findings of HLA-B52 positivity and diffusely affected vessels in patients with EOLVV can be considered as suspicious findings of LV-GCA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02618-4.

Time Trajectory of Pulmonary Artery Involvement in Takayasu Arteritis Confirmed by Histopathology

The early diagnosis of Takayasu arteritis (TAK) remains challenging when TAK-related pulmonary artery involvement occurs as an isolated or initial clinical manifestation. We describe the long-term course of a patient with isolated pulmonary TAK who was initially diagnosed with pulmonary arterial hypertension with in situ thrombus but was re-diagnosed following thromboendarterectomy surgery. (Level of Difficulty: Beginner.).

Evaluation of tocilizumab for intractable Takayasu arteritis and 18F-fluorodeoxyglucose-positron emission tomography for detecting inflammation under tocilizumab treatment

BACKGROUND

Although high-dose glucocorticoids are effective in suppressing active inflammation of Takayasu arteritis (TAK), many patients experience relapse during tapering of glucocorticoids. Recently, the interleukin-6 receptor antibody, tocilizumab (TCZ), was reported to be effective for steroid-resistant TAK. However, there are no objective ways of diagnosing TAK recurrence because TCZ suppresses inflammatory biomarkers.

OBJECTIVES

To investigate the efficacy of TCZ at 1-year follow-up and of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography for detection of recurrence of inflammation during TCZ treatment.

METHODS AND RESULTS

We treated 19 patients with refractory TAK with TCZ. TCZ was discontinued in 2 cases because of side effects. Abatement of arteritis symptoms along with reduction of glucocorticoid dosage was achieved in 12 patients, resulting in a remission induction rate of 70.6%. The dosage of glucocorticoid was reduced from 16.1 ± 10.2 mg to 3.8 ± 1.7 mg at 1 year (p<0.001) in these patients. In the remaining 5 patients, glucocorticoid tapering led to exacerbation of symptoms and glucocorticoid dose had to be increased. FDG-PET scan results closely matched clinical course in all 5 patients with recurrence even during TCZ treatment, while the scan was negative for the remaining 12 patients.

CONCLUSIONS

TCZ injection provides robust steroid-sparing effect and improvement of inflammation without significant adverse effects. Recurrence of inflammation can be detected by FDG-PET even during TCZ treatment.

Pathogenesis of liver injury in Takayasu arteritis: advanced understanding leads to new horizons

Liver injury in Takayasu arteritis (TA) is a rare phenomenon. Most symptoms are nonspecific, and the exact pathogenesis remains to be elucidated. Early diagnosis and new treatment methods are important for an improved prognosis. A summary of the clinical information and mechanistic analyses may contribute to making an early diagnosis and development of new treatment methods. A PubMed search was conducted using the specific key words “Takayasu arteritis” and “liver” or “hepatitis” or “hepatic”. Symptoms and treatment of TA with an accompanying liver injury were reviewed retrospectively. Many factors are presumed to be involved in the mechanism of TA with liver injury, including the immune response, genes, infections, and gut microbiota. There are several lines of evidence indicating that immune dysfunction is the main pathogenic factor that triggers granuloma formation in TA patients. However, the role of genetics and infections has not been fully confirmed. Recently, the gut microbiota has emerged as an essential component in the process. We reviewed in detail the current concepts that support the complex pathogenesis of TA accompanied by liver injury, and we presented recent theories from the literature. Finally, we discussed future research directions of liver injury in TA.

Single-Nucleotide Polymorphism of the MLX Gene Is Associated With Takayasu Arteritis

BACKGROUND

Takayasu arteritis (TAK) is an autoimmune systemic arteritis of unknown pathogenesis. Genome-wide association studies revealed that single-nucleotide polymorphisms in the MLX gene encoding the MLX (Max-like protein X) transcription factor are significantly associated with TAK in Japanese patients. MLX single-nucleotide polymorphism rs665268 is a missense mutation causing the Q139R substitution in the DNA-binding site of MLX.

METHODS

To elucidate the hypothesis that the single-nucleotide polymorphism of the MLX gene plays a critical role in the development of TAK, we conducted clinical and laboratory analyses.

RESULTS

We show that rs665268 significantly correlated with the severity of TAK, including the number of arterial lesions and morbidity of aortic regurgitation; the latter may be attributed to the fact that MLX mRNA expression was mostly detected in the aortic valve. Furthermore, the Q139R mutation caused structural changes in MLX, which resulted in enhanced formation of a heterodimer with MondoA, upregulation of TXNIP (thioredoxin-interacting protein) expression, and increase in the activity of the NLRP3 (NACHT, LRR, and PYD domains-containing protein 3) inflammasome and cellular oxidative stress. Furthermore, autophagy, which negatively regulates inflammasome activation, was suppressed by the Q139R mutation in MLX. The MLX-Q139R mutant significantly induced macrophage proliferation and macrophage-endothelium interaction, which was abolished by the treatment with SBI-477, an inhibitor of MondoA nuclear translocation. Our findings suggest that the Q139R substitution in MLX plays a crucial role in the pathogenesis of TAK.

CONCLUSIONS

MLX-Q139R mutation plays a crucial role in the pathogenesis of TAK through promoting inflammasome formation.

Novel HLA class I associations with HIV-1 control in a unique genetically admixed population

Associations between HLA class I alleles and HIV progression in populations exhibiting Amerindian and Caucasian genetic admixture remain understudied. Using univariable and multivariable analyses we evaluated HLA associations with five HIV clinical parameters in 3,213 HIV clade B-infected, ART-naïve individuals from Mexico and Central America (MEX/CAM cohort). A Canadian cohort (HOMER, n = 1622) was used for comparison. As expected, HLA allele frequencies in MEX/CAM and HOMER differed markedly. In MEX/CAM, 13 HLA-A, 24 HLA-B, and 14 HLA-C alleles were significantly associated with at least one clinical parameter. These included previously described protective (e.g. B*27:05, B*57:01/02/03 and B*58:01) and risk (e.g. B*35:02) alleles, as well as novel ones (e.g. A*03:01, B*15:39 and B*39:02 identified as protective, and A*68:03/05, B*15:30, B*35:12/14, B*39:01/06, B*39:05~C*07:02, and B*40:01~C*03:04 identified as risk). Interestingly, both protective (e.g. B*39:02) and risk (e.g. B*39:01/05/06) subtypes were identified within the common and genetically diverse HLA-B*39 allele group, characteristic to Amerindian populations. While HLA-HIV associations identified in MEX and CAM separately were similar overall (Spearman's rho = 0.33, p = 0.03), region-specific associations were also noted. The identification of both canonical and novel HLA/HIV associations provides a first step towards improved understanding of HIV immune control among unique and understudied Mestizo populations.

Surgical strategy for refractory aortitis

In some instances, we encounter cases suffered from inflammatory aortic diseases (aortitis) in Japan, some of which are at the active stages with systemic inflammation. Most of them are refractory with some technical difficulties of surgical treatment. The aortic wall, particularly, at the active stage, is too fragile to hold the surgical sutures. Consequently, the suture reinforcement with Teflon felt is required. In the late stage after surgery, false aneurysms on the suture line, that is, suture detachment potentially occur. To prevent such sequelae in the early and late phases, continuous (life-long) as well as perioperative inflammation control using corticosteroid as an initial drug and/or other immunosuppression agents. This decade, instead of the conventional open surgical repairs, endovascular treatments have widely spread, predominantly for stenotic aortic/arterial lesions. In particular, for more difficult patients suffered from more troublesome Behçet disease, endovascular treatments would have greater advantages to avoid more occasionally occurred pseudo-aneurysm on the other parts as well as the surgical suture lines. The key issues on surgical treatment for refractory aortitis are perioperative inflammation control including the long term with corticosteroid and/or immunosuppressive agents, appropriate open surgical or endovascular treatment approaches, and sufficient reinforcement of surgical suture lines.

Diagnosis, Management, and Outcome of Aortitis at a Single Center

BACKGROUND

Aortitis is a rare condition with inflammatory or infectious etiology that can be difficult to diagnose due to the highly variable clinical presentation and nonspecific symptoms. However, current literature on the diagnosis, management, and prognosis of aortitis is extremely scarce.

METHODS

We retrospectively reviewed all patients' charts who were diagnosed with giant cell arteritis, Takayasu arteritis, or noninfectious aortitis presenting at a single center between January 1, 2009, and April 17, 2015. Data collected included demographics, medical history, comorbidities, laboratory and imaging data, management, and outcome.

RESULTS

Among the included 15 patients presenting with aortitis at our center, 53% were diagnosed with Takayasu arteritis, 33% with idiopathic inflammatory aortitis, and 13% with giant cell arteritis. All patients received steroid treatment, 67% received adjunctive immunosuppressants or immunomodulators, and 33% underwent interventional procedures. Based on clinical presentation and laboratory and imaging findings at the last follow-up visit for each patient, 67% showed improvement, 27% had no change in disease activity, and 7% had a progression of the disease.

CONCLUSIONS

Takayasu arteritis was found to be more common than idiopathic inflammatory aortitis and giant cell arteritis among our 15 cases diagnosed with aortitis. All patients received medical therapy and 33% received interventional procedures, leading to 67% improvement of disease activity or related complications. This article also offers a comprehensive review of the diagnosis, management, and outcome of aortitis, supplementing the very limited literature on this disease.

The genetics of Takayasu arteritis

Takayasu arteritis (TAK) is a rare systemic vasculitis that is characterized by granulomatous inflammation of the aorta and its major branches. The cellular and biochemical processes involved in the pathogenesis of TAK are beginning to be elucidated, and implicate both cell and antibody-mediated autoimmune mechanisms. In addition, the underlying etiology to TAK may be explained, at least in part, by a complex genetic contribution. The most well-recognized genetic susceptibility locus for the disease is the classical HLA allele, HLA-B*52, which has been confirmed in several ethnicities. The genetic susceptibility with HLA-B*52, as well as additional classical alleles and loci, implicate both HLA class I and class II involvement in TAK. Furthermore, genetic associations with genes encoding immune response regulators, pro-inflammatory cytokines and mediators of humoral immunity may directly relate to disease mechanisms. Non-HLA susceptibility loci that have been recently established for TAK with a genome-wide level of significance include FCGR2A/FCGR3A, IL12B, IL6, RPS9/LILRB3, and a locus on chromosome 21 near PSMG1. In this review, we present the complex genetic predisposition to TAK and discuss how recent findings identified potential targets in the pathogenesis and treatment of the disease.

Lack of association between polymorphisms in interleukin (IL)-12, IL-12R, IL-23, IL-23R genes and Takayasu arteritis in a Chinese population

OBJECTIVE

The goal of this study was to investigate the relationship between polymorphisms in interleukin (IL)-12, IL-12R, IL-23, and IL-23R genes and Takayasu arteritis (TA) in a Chinese population.

METHODS

A case-control study was performed to investigate the associations of 19 single nucleotide polymorphisms (SNPs) mapping to IL12A, IL12B, IL12RB1, IL12RB2 and IL23R with susceptibility to TA in 145 Chinese TA patients and 300 healthy controls. Genotype identification was performed with the MassARRAY system from Sequenom. The statistical analysis was conducted by Chi square test and unconditional logistic regression with plink.

RESULTS

No significant differences were found for the distribution of allele and genotype frequencies of these SNPs between TA patients and healthy controls. However, a trend for IL12A rs582054 and IL23R rs1004819 in association with the TA phenotype was detected. TA patients carrying the rs582054/rs568408 haplotype (P' = 0.019) appeared less likely to progress to a more severe form of disease. And the C allele (P' = 0.082) of IL23R rs1004819 appeared to be a protective factor to refractory disease.

CONCLUSIONS

These findings suggest that the polymorphisms of IL12A, IL12B, IL12RB1, IL12RB2 and IL23R might make no contribution to the susceptibility of TA in the Chinese population.

Large Vessel Vasculitis with an Isolated Lesion of a Single-lobe Pulmonary Artery

Chronic pulmonary arterial obstructions are caused mostly by chronic pulmonary artery thromboembolism and rarely by vasculitis or intimal sarcoma of the pulmonary artery. We herein report an unusual case of a 42-year-old woman with a solitary obstruction of the pulmonary artery in the right lower lobe of her lung. Because we could not exclude the possibility of intimal sarcoma, middle and lower lobectomy was performed. The resected specimens revealed large vessel vasculitis (LVV) and an isolated lesion in the right lower lobe pulmonary artery. LVV should therefore be considered in the differential diagnosis for single pulmonary arterial stenosis or obstruction.

Revisited HLA and non-HLA genetics of Takayasu arteritis--where are we?

Takayasu arteritis (TAK) is an immune-mediated vasculitis affecting large arteries first reported in 1908 from Japan. Case reports of familial onset of TAK from Japan and other countries indicated genetic contribution to TAK onset beyond ethnicity. Genetic studies of TAK have been performed mainly addressing the human leukocyte antigen (HLA) locus. HLA genetic studies of TAK that have previously been reported are reviewed in this manuscript. HLA-B*52:01 is associated with TAK beyond population. Many of the associations other than HLA-B*52:01 can be explained by a haplotype with HLA-B*52:01. HLA-B*67:01 is a novel susceptibility HLA-B allele to TAK confirmed in the Japanese population. Further independent associations are suggested in the HLA locus. Involvement of the 171st and 67th amino acid residues with TAK onset has been indicated. The 67th amino acid may explain the difference in susceptibility effects to TAK and Behçet's disease between HLA-B*52:01 and *51:01. HLA-B*52:01 is associated not only with TAK susceptibility but also with clinical phenotypes. Recent genome-wide association studies of TAK revealed multiple non-HLA susceptibility genes. In particular, the IL12B region seems to have a central role in TAK onset and its progression. Whether TAK and giant cell arteritis (GCA), the other vasculitis affecting large arteries, are the same disease is an interesting question to address in spite of different clinical manifestations between the two diseases. GCA is associated with HLA-DR4, which is not associated with TAK. GCA is not associated with HLA-Bw52. These two diseases seem not to share non-HLA susceptibility loci based on the recent genetic studies.

Takayasu arteritis and ulcerative cutaneous sarcoidosis

A 67-year-old woman was referred to our hospital due to a refractory lower extremity ulcer. Occlusion of the bilateral superficial femoral arteries and a difference (>50 mmHg) in blood pressure between the bilateral upper limbs were noted. In addition to occlusion of the left subclavian artery and stenosis at the ostium of the right coronary artery, these findings led to a diagnosis of Takayasu arteritis. Furthermore, a biopsy of the ulcerated skin lesion localized on the fibular surface showed a non-caseating cutaneous granulomatous lesion resulting in the diagnosis of cutaneous sarcoidosis. The simultaneous occurrence of cutaneous sarcoidosis and Takayasu arteritis, albeit rare, should not be overlooked.

[Large vessel vasculitis]

Giant cell arteritis (GCA) and Takayasu arteritis (TA) are the two diseases characterized as large vessel vasculitis (LVV) and are autoimmune diseases with granulomatous inflammation that affect medium and large sized arteries. These diseases are accompanied by symptoms of systemic inflammatory reactions typically including fatigue, weight loss and low grade fever as well as elevation of the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels. More specific symptoms include headache and visual symptoms for GCA and arm or leg claudication, renal hypertension and angina pectoris for TA. Imaging studies to demonstrate inflammatory vascular wall lesions and biopsy of the temporal artery for GCA are the most relevant diagnostic procedures. Treatment relies mainly on glucocorticoids. Methotrexate seems to have a moderate glucocorticoid-sparing effect but evidence for other immunosuppressants, including azathioprine, tocilizumab and cyclophosphamide is limited. Revascularization methods might also be required in TA.

A Case of Membranous Glomerulonephropathy Associated with Takayasu's Arteritis

Glomerulonephropathy is a rare complication of Takayasu's arteritis (TA). To date, most glomerulonephropathies associated with TA show the histological feature of mesangial proliferation. Membranous glomerulonephropathy (MG) is a form of glomerulonephropathy in which the mesangial proliferation is not conspicuous and its association with TA is extremely rare. A 54-year-old man was referred to our hospital due to progressive edema in the lower limbs and nephrotic range proteinuria. Five years previously, he underwent percutaneous angioplasty for left subclavian artery stenosis. Kidney biopsy revealed stage II MG. General examination including enhanced CT scan confirmed the presence of TA. He started oral prednisolone therapy at a dose of 40 mg daily. The C-reactive protein level normalized 7 days after the prednisolone therapy. Three months later, proteinuria had remitted. Though the true relationship between MG and TA was not revealed in present case, considering the fact that complete remission of nephrotic syndrome occurred following the improvement of C-reactive protein level in response to steroid therapy, TA might be the secondary cause of MG. To our best knowledge, only two case reports described the association of MG and TA previously. Those two patients, however, also demonstrated the feature of systemic lupus erythematosus in addition to TA. This is the first case report that describes a patient who presented as MG associated with TA, but not complicated by systemic lupus erythematosus.

The Molecular Biology and Treatment of Systemic Vasculitis in Children

Primary systemic vasculitides are rare in childhood but are associated with significant morbidity and mortality. The cause of the majority of vasculitides is unknown, although it is likely that a complex interaction between environmental factors, such as infections and inherited host responses, triggers the disease and determines the vasculitis phenotype. Several genetic polymorphisms in vasculitides have now been described, which may be relevant in terms of disease predisposition or development of disease complications. Treatment regimens continue to improve with the use of different immunosuppressive medications and newer therapeutic approaches such as biologic agents. This chapter reviews recent studies shedding light on the pathogenesis of vasculitis with emphasis on molecular biology where known, and summarizes current treatment strategies. We discuss new emerging challenges particularly with respect to the long-term cardiovascular morbidity for children with systemic vasculitis and emphasize the importance of future international multicenter collaborative studies to further increase and standardize the scientific base investigating and treating childhood vasculitis.

Takayasu's arteritis is associated with HLA-B*52, but not with HLA-B*51, in Turkey

Introduction

HLA-B*51 and HLA-B*52 are two close human leukocyte antigen (HLA) allele groups with minor amino acid differences. However, they are associated with two different vasculitides (HLA-B*51 in Behçet's disease and HLA-B*52 in Takayasu's arteritis (TAK)) and with major clinical and immunological differences. In this study, we aimed to screen a large cohort of TAK patients from Turkey for the presence of HLA-B*51 and HLA-B*52 as susceptibility and severity factors.

Methods

TAK patients (n = 330) followed at a total of 15 centers were included in the study. The mean age of the patients was 37.8 years, and 86% were women. DNA samples from the patients and healthy controls (HC; n = 210) were isolated, and the presence of HLA-B*51 or HLA-B*52 was screened for by using PCR with sequence-specific primers.

Results

We found a significant association of HLA-B*52 with TAK (20.9% vs HC = 6.7%, P = 0.000, OR = 3.7, 95% CI = 2.02 to 6.77). The distribution of HLA-B*51 did not differ between TAK patients and HCs (22.7% vs 24.8%, OR = 0.9, 95% CI = 0.60 to 1.34). The presence of HLA-B*52 decreased in late-onset patients (> 40 years of age; 12.0%, P = 0.024, OR = 0.43, 95% CI = 0.20 to 0.91). Patients with angiographic type I disease with limited aortic involvement also had a lower presence of HLA-B*52 compared to those with all other disease subtypes (13.1% vs 26%, P = 0.005, OR = 0.43, 95% CI = 0.23 to 0.78).

Conclusions

In this study, the previously reported association of TAK with HLA-B*52 in other populations was confirmed in patients from Turkey. The functional relevance of HLA-B*52 in TAK pathogenesis needs to be explored further.

Genome-wide association study identifies HLA-DP as a susceptibility gene for pediatric asthma in Asian populations

Asthma is a complex phenotype influenced by genetic and environmental factors. We conducted a genome-wide association study (GWAS) with 938 Japanese pediatric asthma patients and 2,376 controls. Single-nucleotide polymorphisms (SNPs) showing strong associations (P<1×10⁻⁸) in GWAS were further genotyped in an independent Japanese samples (818 cases and 1,032 controls) and in Korean samples (835 cases and 421 controls). SNP rs987870, located between HLA-DPA1 and HLA-DPB1, was consistently associated with pediatric asthma in 3 independent populations (P_combined = 2.3×10⁻¹⁰, odds ratio [OR] = 1.40). HLA-DP allele analysis showed that DPA1*0201 and DPB1*0901, which were in strong linkage disequilibrium, were strongly associated with pediatric asthma (DPA1*0201: P = 5.5×10⁻¹⁰, OR = 1.52, and DPB1*0901: P = 2.0×10⁻⁷, OR = 1.49). Our findings show that genetic variants in the HLA-DP locus are associated with the risk of pediatric asthma in Asian populations.

Asthma is the most common chronic disorder in children, and asthma exacerbation is an important cause of childhood morbidity and hospitalization. Here, taking advantage of recent technological advances in human genetics, we performed a genome-wide association study and follow-up validation studies to identify genetic variants for asthma. By examining 6,428 Asians, we found rs987870 and HLA-DPA1*0201/DPB1*0901 were associated with pediatric asthma. The association signal was stretched in the region of HLA-DPB2, collagen, type XI, alpha 2 (COL11A2), and Retinoid X receptor beta (RXRB), but strong linkage disequilibrium in this region made it difficult to specifically identify causative variants. Interestingly, the SNP (or the HLA-DP allele) associated with pediatric asthma (Th-2 type immune diseases) in the present study confers protection against Th-1 type immune diseases, such as type 1 diabetes and rheumatoid arthritis. Therefore, the association results obtained in the present study could partially explain the inverse relationship between asthma and Th-1 type immune diseases and may lead to better understanding of Th-1/Th-2 immune diseases.

A single nucleotide polymorphism in the 3'-untranslated region of MyD88 gene is associated with Buerger disease but not with Takayasu arteritis in Japanese

Buerger disease (BD) and Takayasu arteritis (TA) are rare vascular disorders. Although their etiology and pathogenesis have not been elucidated, several studies have suggested the involvement of innate immunity. Myeloid differentiation primary-response protein 88 (MyD88) is a key signaling adaptor for all Toll-like receptors, which have a central role in innate immunity. In the present study, we evaluated the association of MyD88 with BD and TA. We conducted case-control studies in Japanese populations composing of 131 BD cases, 90 TA cases and 270 healthy controls to be genotyped for a single nucleotide polymorphism rs7744 A>G in the 3'-untranslated region of MyD88 gene. The frequency of GG genotype was significantly lower in the BD patients than in the controls (6.9 vs 15.9%, P=0.011, odds ratio=0.39, 95% confidence interval; 0.19, 0.81), although there was no significant difference in the genotype frequencies between the TA patients and controls. It was suggested that MyD88 may confer resistance to BD in Japanese. Because this is the first report of the association between MyD88 and BD, replication studies in other cohorts are required.

The contribution of Asian researchers to the field of rheumatology

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

Takayasu arteritis in France: a single-center retrospective study of 82 cases comparing white, North African, and black patients

We conducted a single-center retrospective study to compare the characteristics of Takayasu arteritis (TA) among white, North African, and black patients in a French tertiary care center (Hospital Pitié-Salpêtrière, Paris). Eighty-two patients were studied (82.9% female) during a median follow-up of 5.1 years (range, 1 mo to 30 yr). Among these 82 patients, 39 (47.6%) were white, 20 (24.4%) were North African, and 20 (24.4%) were black patients. Median age at diagnosis was 39.3 years (range, 14-70 yr) in white patients vs. 28.4 years (range, 12-54 yr) in North African (p = 0.02), and 28.0 years (range, 13-60 yr) in black patients (p = 0.08). Patients aged >40 years at TA onset were more frequently white than non-white (40.0% vs. 18.6%, p = 0.03). North African patients had more frequent occurrence of ischemic stroke (p = 0.03) and poorer survival (p = 0.01) than white patients. Type V of the Hata classification was the most frequent type among white (38.5%), North African (65.0%), and black patients (40.0%). Corticosteroids were used in 96.1% of patients. Fifty-three percent of white and North African patients, and 44% of black patients required a second line of immunosuppressive treatment (p = 0.60). Vascular surgical procedures were respectively performed in 46.1%, 50.0%, and 55.0% of white, North African, and black patients, p = 0.81. The 5-year and 10-year survival rates were 100% and 95.0%, respectively, in white patients; 67.4% at both 5 years and 10 years in North African patients; and 100% at both 5 years and 10 years in black patients. This study is one of the first direct comparisons of TA profiles among patients of distinct ethnic backgrounds. Our data support the idea that late-onset TA or an overlap between TA and large-vessel giant cell arteritis may be observed in white patients. North African patients have a higher occurrence of ischemic stroke and poorer survival than white patients.

A novel HLA-B allele, B*5214, detected in a Taiwanese volunteer bone marrow donor using a sequence-based typing method

HLA-B*5214, a novel rare allele of HLA-B*52 variant, was found in a Taiwanese volunteer bone marrow donor by sequence-based typing method. The sequence of B*5214 is identical to that of B*520101 in exon 2 but differs from B*520101 in exon 3 at nucleotide positions 419 A-->T and 435 A-->G. Alteration of these two nucleotides resulted an amino acid substitution at amino acid residue 116 Y-->F ( TAC-->TTC) and a silent exchange at residue 121 K-->K (AAA-->AAG).

Takayasu disease on the centenary of its discovery

Takayasu disease was first reported in 1908 by Mikito Takayasu as "a case of peculiar changes in the central retinal vessels." Because in these patients the pulse of the radial artery is impalpable, investigations focusing on the ischemic symptoms of the upper body were conducted. In 1948, Shimizu and Sano named this pathological condition "pulseless disease." Since then, the lesions of Takayasu disease have been detected not only in the aortic arch and its main branches but also in various vessels, including the abdominal aorta and renal arteries. The ocular symptoms of Takayasu disease are considered to be due to ischemia in the retina and choroid. The typical wreath-like arteriovenous anastomosis around the disc reported by Takayasu is observed at a relatively late stage of the disease. The characteristic fundus findings of Takayasu disease include tortuosity and dilatation of the central retinal artery and vein, retinal arteriovenous anastomosis, prominent retinal vasculature, microaneurysms in the capillaries, occlusion of retinal arterioles, soft exudate, choked disc, and optic atrophy. Fluorescein angiography reveals retinal microaneurysms, sludging, slower blood flow, dilatation of retinal vessels, leakage of fluorescence dye due to increased vascular permeability, and arteriovenous anastomosis. Arteriovenous anastomosis initially appears in the periphery at the early stage, and in the arteriovenous crossing at the advanced stage. Systemic administration of corticosteroids is required to prevent vascular stenosis during the early stages of Takayasu disease. Reconstruction of the carotid artery may improve subjective symptoms and fundus findings.