The presence of both HLA-DRB1[*]04:01 and HLA-B[*]15:01 increases the susceptibility to cranial and extracranial giant cell arteritis.

Objectives: To determine if patients with the predominant extracranial large-vessel-vasculitis (LVV) pattern of giant cell arteritis (GCA) have a distinctive HLA-B association, different from that reported in biopsy-proven cranial GCA patients. In a further step we assessed if the combination of HLA-B and HLA-DRB1 alleles confers an increased risk for GCA susceptibility, either for the cranial and extracranial LVV phenotypes. Methods: A total of 184 patients with biopsy-proven cranial GCA, 105 with LVV-GCA and 486 healthy controls were included in our study. We compared HLA-B phenotype frequencies between the three groups. Results: HLA-B*15 phenotype was significantly increased in patients with classic cranial GCA compared to controls (14.7% versus 5.8%, respectively; p<0.01; OR [95% CI] =2.81 [1.54-5.11]). It was mainly due to the HLA-B*15:01 allele (12.5% versus 4.0%, respectively; p<0.01; OR [95% CI] =3.51 [1.77-6.99]) and remained statistically significant after Bonferroni correction. Similar HLA-B*15 association was observed in patients with the LVV-GCA (11.4% versus 5.8%, p=0.04, OR [95% CI] =2.11 [1.04-4.30]). This association was also mainly due to the HLA-B*15:01 allele (10.5% versus 4.0%, respectively; p=0.0054; OR [95% CI] =2.88 [1.19-6.59]). Noteworthy, the presence of HLA-B*15:01 together with HLA-DRB1*04:01 led to an increased risk of developing both cranial and extracranial LVV-GCA. Conclusions: Susceptibility to GCA is strongly related to the HLA region, regardless of the clinical phenotype of expression of the disease.This work was partially supported by RETICS Programs, RD08/0075 (RIER), RD12/0009/0013 and RD16/0012 from ‘‘Instituto de Salud Carlos III’’ (ISCIII) (Spain). However, this research did not receive any specific grant from funding agencies in the commercial or not-for-profit sectors

Cranial and extracranial giant cell arteritis share similar HLA-DRB1 association

Objective:To determine whether giant cell arteritis (GCA) patients with the typical pattern of cranial ischemicmanifestations and those with the extracranial large-vessel-vasculitis (LVV)-GCA phenotype exhibit differentHLA-DRB1association.Methods:178 biopsy-proven GCA patients who had cranial ischemic features but no LVV manifestations, 100patients with LVV-GCA without cranial ischemic manifestations and 486 ethnically matched healthy controlswere recruited. All patients and controls were Spanish of European ancestry. We comparedHLA-DRB1pheno-type frequencies between the three groups.Results:Both GCA subgroups had well-differentiated clinical features. Patients with LVV-GCA were younger(68.0§10.0 yearsversus74.0§10.4 years;p<0.01) and presented more commonly with polymyalgia rheu-matica symptoms (81%versus39.3%;p<0.01) than those with the classic cranial GCA phenotype.HLA-DRB1*04phenotype frequency was significantly increased in patients with classic cranial GCA compared tocontrols (42.1%versus23.5%, respectively;p<0.01; odds ratio-OR [95% confidence interval-CI] = 2.38[1.623.47]). This association was mainly due to theHLA-DRB1*04:01allele (20.8%versus5.3%, respectively;p<0.01; OR [95% CI] = 4.64 [2.638.26]).HLA-DRB1*04association was also observed in LVV-GCA patientswhen compared to controls (46.0%versus23.5%, respectively;p<0.01; OR [95% CI] = 2.78 [1.734.44])

Influence of IL17A gene on the pathogenesis of immunoglobulin-A vasculitis

OBJECTIVES: Cytokines signaling pathway genes represent a key component of the genetic network implicated in the pathogenesis of immunoglobulin-A vasculitis (IgAV), an inflammatory vascular pathology. Interleukin (IL)17A is described as a genetic risk locus for some autoimmune diseases, such as giant cell arteritis and spondyloarthritis. Accordingly, we aimed to determine the potential influence of IL17A on the pathogenesis of IgAV. METHODS: Five IL17A tag polymorphisms (rs4711998, rs8193036, rs3819024, rs2275913 and rs7747909), which cover the major variability of this gene, were genotyped in 360 Caucasian patients with IgAV and 1,003 sex and ethnically matched healthy controls using TaqMan probes. RESULTS: No statistically significant differences between patients with IgAV and healthy controls were observed when each IL17A genetic variant was analysed independently. Similarly, no statistically significant differences between patients with IgAV and healthy controls were found when the five IL17A polymorphisms were evaluated combined conforming haplotypes. In addition, there were no statistically significant differences in genotype, allele and haplotype frequencies of IL17A when patients with IgAV were stratified according to the age at disease onset or to the presence/absence of gastrointestinal or renal manifestations. CONCLUSIONS: Our results do not support an influence of IL17A on the pathogenesis of IgAV

Role of IRF5 in the pathogenesis of immunoglobulin-A vasculitis

OBJECTIVES: Interferon regulatory factor 5 (IRF5) is a major regulator of type I interferon induction and is also critical to produce pro-inflammatory cytokines. An influence of IRF5 genetic variants on the increased risk of immune-mediated diseases has been described. Accordingly, we aimed to evaluate the implication of IRF5 in the pathogenesis of Immunoglobulin-A vasculitis (IgAV), an inflammatory vascular pathology. METHODS: Three tag genetic variants (rs2004640, rs2070197 and rs10954213), representative of 3 different haplotype blocks within IRF5, were genotyped in 372 Caucasian patients with IgAV and 876 sex and ethnically matched healthy controls by TaqMan assays. RESULTS: No significant differences in the genotype and allele frequencies between patients with IgAV and healthy controls were observed when each IRF5 polymorphism was evaluated independently. Likewise, no significant differences between patients with IgAV and healthy controls were found when we assessed the three IRF5 polymorphisms combined, conforming haplotypes. In addition, there were no significant differences in genotype, allele and haplotype frequencies of IRF5 when patients with IgAV were stratified according to the age at disease onset or to the presence/absence of gastrointestinal or renal manifestations. CONCLUSIONS: Our results do not support an influence of IRF5 on the pathogenesis of IgAV