Direct role of HLA-B5 in influencing susceptibility to Takayasu aortoarteritis

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.

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.

Comparative study of the residues 63 and 67 on the HLA-B molecule in patients with Takayasu's Arteritis

Takayasu's Arteritis (TA) has been associated with the Major Histocompatibility Complex (MHC) genes; nevertheless, results in several populations have been heterogeneous. Studies both in Mexican and Asian populations suggest that residues at positions 63 (glutamic acid) and 67 (serine) of the HLA-B molecule could be the genetic markers for TA. In the present work, we analyzed the sequence of HLA-B alleles in 26 TA patients and 62 healthy controls. HLA-B subtyping analysis showed that all B52 alleles were B*5201, whereas only one HLA-B39 allele was B*3902. Sequencing of HLA-B alleles showed that 19 out of 26 patients studied (73.0%) presented at least an allele with glutamic acid at position 63 and serine at position 67. This condition was observed in only 21.0% of the healthy controls (pC = 0.00001, OR = 10.23). Out of the seven remaining patients, one presented glutamic acid at position 63 and four showed serine at position 67. Two patients (2/26 = 7.7%) and 24 healthy controls (24/62 = 38.7%) did not show similarity at the mentioned positions (pC = 0.016, OR = 0.13). These data corroborate the participation of positions 63 and 67 in the genetic susceptibility to TA and explain the high heterogeneity of alleles associated with the disease in several populations.

Granulomatous vasculitis

Granulomatous vasculitis is a subset of systemic necrotizing vasculitis and has granulomatous inflammation as the main histopathologic feature. Etiopathogenesis remains poorly understood, although recent advances suggest an important role for certain pro-inflammatory cytokines, such as tumor necrosis factor-alpha. They are a heterogeneous group of clinical disorders with protean manifestations. Serologic abnormalities are present, and the presence of granular cytoplasmic staining-antineutrophil cytoplasmic antibodies is most important and is particularly useful for the diagnosis of active Wegener's granulomatosis. Corticosteroids and cyclophosphamide remain very useful in the treatment of most of these disorders.

Occlusive thromboaortopathy (Takayasu disease): clinical and angiographic features and a brief review of literature

The aim of this study was to evaluate the diagnostic criteria and angiographic classifications of Takayasu arteritis by presenting the clinical, angiographic, and prognostic findings and a prospective follow-up of 78 patients. Occlusive thromboaortopathy or Takayasu arteritis is a large vessel vasculitis. The disease is systemic with an autoimmune and genetic etiology. The complete clinical and angiographic manifestations are reported for 78 cases based on diagnostic criteria of the American College of Rheumatology with a mean 6 +/- 3.2 years follow-up. The mean age was 34.7 and female:male ratio was 3.6:1. According to National Institute of Health criteria, 61.5% of patients were in the acute phase of disease with systemic symptoms such as fever, weight loss, malaise, and elevated C-reactive protein levels. Immunologic markers, such as antinuclear antibody and antineutrophil cytoplasmic antibodies, were negative. The tuberculin test result was positive in 47%. Vascular bruit was present in 89%. Almost all patients had stenoses, occlusions, or aneurysmatic changes of the aorta and its main branches. Hypertension was detected in 58% and left ventricular hypertrophy was initially present in 22 (28%) patients. The angiographic manifestations were classified as type I, cervicobrachial type with 20 cases (25.6%); type II, thoracoabdominal type with 13 cases (16.6%); type III, peripheral type with 10 cases (12.8%); and type IV, generalized type with 35 cases (44.8%). The coronary arteries were involved in 6 cases, pulmonary arteries in 11 initially 5 in follow-up (16 cases), and renal arteries in 28 cases, respectively. A good correlation of the clinical manifestations and the prognosis was observed. During follow-up, five patients suffered from myocardial infarction, six had cerebrovascular accident, seven patients underwent aortic valve replacement, and six patients died (mortality rate, 7.6%). The specificity and sensitivity of diagnostic criteria were 94% and 76%, respectively. In contrast to ours and Nasu's classification in the new classification of Numano, some angiographic types and subtypes of Takayasu arteritis are not present in our patients.

Association of HLA-DRB1*1602 and DRB1*1001 with Takayasu arteritis in Colombian mestizos as markers of Amerindian ancestry

We performed HLA Class I and Class II typing in 16 patients (15 women, one man) with a confirmed diagnosis of Takayasu arteritis. We did not find any of the previously described associations with HLA-B52, and/or HLA-DRB1*1301 alleles. However, in our patients, HLA-DRB1*1602 and HLA-DRB1*1001 were significantly increased. The association of Takayasu arteritis with Amerindian and Asian HLA-DRB1 alleles (DRB1*1602 and DRB1*1001) in the Colombian mestizo patients reported here, and with HLA-B*3906 previously reported in Mexicans, suggest the possibility that some HLA and disease associations are markers for ethnicity of a population carrying a disease gene which is present in an admixed population with the disease.

DNA typing of HLA class II genes (HLA-DR, -DQ and -DP) in Japanese patients with histiocytic necrotizing lymphadenitis (Kikuchi's disease)

The pathogenesis of histiocytic necrotizing lymphadenitis (HNL), which was reported first by Kikuchi et al. and Fujimoto et al. in 1972, is as yet unknown. HNL is frequently reported in Asian countries including Japan, however it is rare in Europe and North America. To elucidate whether the human leukocyte antigen (HLA) alleles and haplotypes are associated with HNL, we performed DNA typing of HLA class II genes (HLA-DR, -DQ, and -DP) in 86 patients with HNL and 525 unrelated healthy Japanese controls with polymerase chain reaction using sequence-specific oligonucleotide probes (PCR-SSOP). In this study, we found DPA1*01 and DPB1*0202 allele frequencies in HLA class II genes are significantly higher in HNL patients than in normal controls. It is known that the frequency of DPB1*0202 alleles is extremely low or absent in Caucasians (e.g., French 0.4%, Italian 0.8%) and Negroid (e.g., South African 0%, Hottentot 0%), but relatively frequent in Asians (e.g., Korean 9.9%, Japanese 4.5%). Previous reports have said the incidence of HNL is frequent in Asians but rare in other races. In light of this background, HLA class II genes of HNL and the incidence of HNL in Asian countries, including Japan, might have a positive relationship to DPA1*01 and DPB1*0202 allele.

Takayasu's arteritis: a cell-mediated large-vessel vasculitis

Takayasu's arteritis is an idiopathic, systemic inflammatory disease, typically involving the aorta and its main branches. Cell-mediated autoimmunity has been strongly implicated in its pathogenesis. Early or active-stage pathology consists of continuous or patchy granulomatous inflammation, which progresses to intimal and adventitial fibrosis and scarring of the media. Multiple focal or segmental stenoses result and aneurysms may occasionally occur. Clinical presentation is heterogeneous, ranging from asymptomatic to catastrophic. In some patients, constitutional signs and symptoms indicating a systemic inflammatory response are observed, usually in the early stages. Specific features reflect arterial involvement, and result from end-organ or limb ischemia; they include vascular, neurological, cardiac, and pulmonary manifestations. The course of Takayasu's arteritis usually extends for many years with varying degrees of activity. Takayasu's arteritis has a worldwide distribution, with the greatest prevalence in eastern countries. Women of reproductive age are preferentially affected, but the illness is being recognized with increasing frequency in males. Variable phenotypes are recently emerging in different ethnic groups. Diagnosis is based on clinical features and vascular imaging studies that document typical patterns of stenoses or aneurysms of the aorta and its primary branches. Assessment of the activity of Takayasu's arteritis is imprecise, in that clinical features and acute-phase reactants do not accurately reflect active blood vessel inflammation. High-dose corticosteroids alone or a cytotoxic agent in addition to a corticosteroid may be effective in treating active disease. Critical lesions may require correction by surgery or interventional radiology.

The association between the HLA antigens and Takayasu's arteritis in Thai patients

The HLA-A, -B, -DR and -DQ antigen distribution in 20 unrelated Thai patients with Takayasu's arteritis was compared with that in 44 healthy controls. The frequency of HLA-A31 and HLA-B52 (chi2=4.54, P<0.05; chi2=3.80, P<0.05, RR=7.5) appeared to be increased in the patient group. In contrast, the frequency of HLA-A24 and HLA-DQ3 (chi2=4.18, P<0.05, RR=0.25; chi2=5.36, P<.025, RR=0.28) appeared to be decreased in this group.

Molecular analyses of HLA class II-associated susceptibility to subtypes of autoimmune diseases unique to Asians

It is well known that individuals positive for particular HLA-class II alleles show high risks for the development of Takayasu arteritis and other diseases caused by immunological disorders such as autoimmune diseases and allergies. HLA class II molecules present antigenic peptides to CD4+ T cells. Their extensive polymorphism affects the structures of peptides bound to HLA class II molecules to create individual differences in immune responses to antigenic peptides. To better understand the mechanisms for association between HLA class II alleles and susceptibility to autoimmune diseases, it is important to identify self-peptides presented by disease-susceptible HLA class II molecules and triggering disease-causative T cells. Many autoimmune diseases are observed in all ethnic groups, whereas the incidences of diseases, clinical manifestations and disease-susceptible HLA class II alleles are different among various ethnic groups for some autoimmune diseases. These phenomena suggest that differences in autoimmune self-peptide(s) in the context of disease-susceptible HLA class II molecules may cause these differences. Therefore, comparisons among disease-susceptible HLA class II alleles, autoimmune self-peptides and clinical manifestations of autoimmune diseases in different ethnic groups would be helpful in determining the pathogenesis of the diseases. In this paper, we describe our recent findings on: (1) the uniqueness of both clinical manifestations and HLA-linked genetic background of Asian-type (optico-spinal form) multiple sclerosis; (2) the structural characteristics of peptides bound to HLA-DQ molecules susceptible to insulin-dependent diabetes mellitus; (3) the identification of a disease-related autoantigenic peptide presented by disease-susceptible HLA-DQ molecules in Asians-specific infant onset myasthenia gravis; and (4) a manipulation of human T cell response by altered peptide ligands, as a possible candidate for new and antigen-specific immuno-suppressive therapy against autoimmune diseases.

Demographic, clinical, and angiographic data of patients with Takayasu arteritis in Brazil

We collected clinical, demographic, and angiographic data of Takayasu arteritis (TA) patients followed at Rheumatology Division of three Public University Centers (UNIFESP, USP, and UNICAMP) located in São Paulo State, Brazil. Clinical and demographic data were obtained from 73 patients (61 female; 50 white) The mean age at time of diagnosis was 27 y.o. and the mean follow-up time was 5 years. The following clinical features were observed along the evolution of these patients: absent or reduced pulses in upper limbs (85%), arterial bruit (64.5%), claudication of upper members (57%), headache (45%), hypertension (35.5%), dizziness (29%), cardiac bruit (29%), weight loss (27.5%), arthralgia or arthritis (26%), fever (24.5%) and claudication of lower limbs (20.5%). According to new angiographic classification of Takayasu arteritis performed in 28 patients followed at UNTFESP, with routine full aortography, 21% were classified as type I, 4% as type IIa, 4% as type III, 14% as type IV and 57% as type V. No patients had type IIb. Patients with Takayasu arteritis in São Paulo State Brazil showed female predominance and arterial involvement pattern similar to the one observed in Japan, with more than 20% classified as type I with exclusive involvement of the branches from the aortic arch.