Inmaculada C. Morado

Identification of the PTPN22 functional variant R620W as susceptibility genetic factor for giant cell arteritis

Objective To analyse the role of the PTPN22 and CSK genes, previously associated with autoimmunity, in the predisposition and clinical phenotypes of giant cell arteritis (GCA). Methods Our study population was composed of 911 patients diagnosed with biopsy-proven GCA and 8136 unaffected controls from a Spanish discovery cohort and three additional independent replication cohorts from Germany, Norway and the UK. Two functional PTPN22 polymorphisms (rs2476601/R620W and rs33996649/R263Q) and two variants of the CSK gene (rs1378942 and rs34933034) were genotyped using predesigned TaqMan assays. Results The analysis of the discovery cohort provided evidence of association of PTPN22 rs2476601/R620W with GCA (PFDR=1.06E-04, OR=1.62, CI 95% 1.29 to 2.04). The association did not appear to follow a specific GCA subphenotype. No statistically significant differences between allele frequencies for the other PTPN22 and CSK genetic variants were evident either in the case/control or in stratified case analysis. To confirm the detected PTPN22 association, three replication cohorts were genotyped, and a consistent association between the PTPN22 rs2476601/R620W variant and GCA was evident in the overall meta-analysis (PMH=2.00E-06, OR=1.51, CI 95% 1.28 to 1.79). Conclusions Our results suggest that the PTPN22 polymorphism rs2476601/R620W plays an important role in the genetic risk to GCA.

Influence of the IL17A locus in giant cell arteritis susceptibility

Objective Different lines of evidence have highlighted the role of IL-17A in the inflammatory process occurring in giant cell arteritis (GCA). The aim of the present study was to assess whether the IL17A locus influences GCA susceptibility and its clinical subphenotypes. Methods We carried out a large meta-analysis including a total of 1266 biopsy-proven GCA patients and 3779 healthy controls from four European populations (Spain, Italy, Germany and Norway). Five IL17A polymorphisms (rs4711998, rs8193036, rs3819024, rs2275913 and rs7747909) were selected by tagging and genotyped using TaqMan assays. Allelic combination and dependency tests were also performed. Results In the pooled analysis, two of the five analysed polymorphisms showed evidence of association with GCA (rs2275913: PMH=1.85E−03, OR=1.17 (1.06–1.29); rs7747909: PMH=8.49E–03, OR=1.15 (1.04–1.27)). A clear trend of association was also found for the rs4711998 variant (PMH=0.059, OR=1.11 (1.00–1.23)). An independent effect of rs2275913 and rs4711998 was evident by conditional regression analysis. In addition, the haplotype harbouring the risk alleles better explained the observed association than the polymorphisms independently (likelihood p value <10−05). Conclusions Polymorphisms within the IL17A locus show a novel association with GCA. This finding supports the relevant role of the Th17 cells in this vasculitis pathophysiology.

Association Between Toll-like Receptor 4 Gene Polymorphism and Biopsy-proven Giant Cell Arteritis

Objective. Dendritic cells localized at the adventitia-media border of the normal medium-sized arteries play a pivotal role in the initiation of giant cell arteritis (GCA). These cells express a singular surface receptor profile, including a series of Toll-like receptors (TLR). Ligands of TLR-4 promote activation and differentiation of adventitial dendritic cells and are directly implicated in the pathogenesis of GCA. We aimed to assess the potential implication of the TLR4-(+896 A/G) gene polymorphism in the susceptibility to GCA. Methods. A total of 210 patients diagnosed with biopsy-proven GCA and 678 matched controls were included in our study. DNA from patients and controls was obtained from peripheral blood. Samples were genotyped for the TLR4-(+896 A/G) (rs4986790) gene polymorphism by polymerase chain reaction, using a predesigned TaqMan allele discrimination assay. Results. The TLR4 +896 G allele was significantly increased in biopsy-proven GCA patients compared to controls [p = 0.01; odds ratio (OR) 1.65; 95% confidence interval (CI) 1.08–2.52]. The increase was due to a significantly increased frequency of heterozygosity for the TLR4 −896 A/G genotype in the group of patients with biopsy-proven GCA compared to controls (TLR4 −896 A/G heterozygous in patients with GCA 18.1% compared to 11.4% in controls: p = 0.01; OR 1.72; 95% CI 1.10–2.69). However, no significant differences were observed when patients with GCA were stratified according to the presence of specific clinical features of the disease. Conclusion. Our results show for the first time an association of TLR4-(+896 A/G) gene polymorphism with susceptibility to biopsy-proven GCA.

Evidence of association of the NLRP1 gene with giant cell arteritis

Recent studies have focused attention on the involvement of NLRP1 to confer susceptibility for extended autoimmune/inflammatory disorders, being considered a common risk factor in autoimmunity.1–3 NLRP1 provides a scaffold for the assembly of the inflammasome that activates caspases 1 and 5, required for processing and activation of the proinflammatory cytokines interleukin 1β (IL-1β), IL-18 and IL-33 and promoting inflammation.4 In this study, we examined for the first time whether NLRP1 is associated with giant cell arteritis (GCA), a chronic systemic vasculitis affecting large and medium-sized arteries derived from the aorta, in particular the cranial branches of the carotid artery. GCA is the most common vasculitis in the elderly in Western countries with a female predominance.5 To investigate the possible genetic association of NLRP1 with this disease, we genotyped a single-nucleotide polymorphism (rs8182352), which has been reported to confer risk to the development of autoimmune processes in previous studies,1 ,2 in a total of 3583 individuals, comprising a discovery set from Spain (574 patients diagnosed with biopsy-proven GCA and 2366 healthy controls) and a replication set of subjects from Italy (111 biopsy-proven GCA patients and 532 controls) using a predesigned TaqMan allele discrimination assay. All individuals were of …

Association between IL-18 gene polymorphisms and biopsy-proven giant cell arteritis

IntroductionThe objective was to investigate the potential implication of the IL18 gene promoter polymorphisms in the susceptibility to giant-cell arteritis (GCA).MethodsIn total, 212 patients diagnosed with biopsy-proven GCA were included in this study. DNA from patients and matched controls was obtained from peripheral blood. Samples were genotyped for the IL18-137 G>C (rs187238), the IL18-607 C>A (rs1946518), and the IL18-1297 T>C (rs360719) gene polymorphisms with polymerase chain reaction, by using a predesigned TaqMan allele discrimination assay.ResultsNo significant association between the IL18-137 G>C polymorphism and GCA was found. However, the IL18 -607 allele A was significantly increased in GCA patients compared with controls (47.8% versus 40.9% in patients and controls respectively; P = 0.02; OR, 1.32; 95% CI, 1.04 to 1.69). It was due to an increased frequency of homozygosity for the IL18 -607 A/A genotype in patients with GCA (20.4%) compared with controls (13.4%) (IL18 -607 A/A versus IL18 -607 A/C plus IL18 -607 C/C genotypes: P = 0.04; OR, 1.59; 95% CI, 1.02 to 2.46). Also, the IL18-1297 allele C was significantly increased in GCA patients (30.7%) compared with controls (23.0%) (P = 0.003; OR, 1.48; 95% CI, 1.13 to 1.95). In this regard, an increased susceptibility to GCA was observed in individuals carrying the IL18-1297 C/C or the IL18-1297 C/T genotypes compared with those carrying the IL18-1297 T/T genotype (IL18-1297 C/C plus IL18-1297 T/C versus IL18-1297 T/T genotype in GCA patients compared with controls: P = 0.005; OR, 1.61; 95% CI, 1.15 to 2.25). We also found an additive effect of the IL18 -1297 and -607 polymorphisms with TLR4 Asp299Gly polymorphism. The OR for GCA was 1.95 for combinations of genotypes with one or two risk alleles, whereas carriers of three or more risk alleles have an OR of 3.7.ConclusionsOur results show for the first time an implication of IL18 gene-promoter polymorphisms in the susceptibility to biopsy-proven GCA. In addition, an additive effect between the associated IL18 and TLR4 genetic variants was observed.

Role of rs1343151 IL23R and rs3790567 IL12RB2 polymorphisms in biopsy-proven giant cell arteritis.

Objective. To assess the potential association between the rs1343151 IL23R and the rs3790567 IL12RB2 polymorphisms and giant cell arteritis (GCA). We also studied whether these polymorphisms might influence the phenotypic expression of GCA. Methods. In total, 357 Spanish patients with biopsy-proven GCA and 574 matched controls were assessed. DNA from patients and controls was obtained from peripheral blood. Samples were genotyped for the rs1343151 IL23R and the rs3790567 IL12RB2 polymorphisms using a predesigned TaqMan allele discrimination assay and by polymerase chain reaction amplification. Results. Regarding the rs1343151 IL23R polymorphism, no significant differences in the genotype or allele frequencies between GCA patients and healthy controls were observed. The frequency of the minor allele A of the rs3790567 IL12RB2 variant was increased in GCA patients compared with controls (30.1% vs 25.7%, respectively; p = 0.039, OR 1.25, 95% CI 1.01–1.54). An increased frequency of subjects carrying the minor allele A (GA+AA genotypes) of the rs3790567 IL12RB2 polymorphism was found among GCA patients compared with controls (52.8% vs 44.4%; p = 0.013, OR 1.40, 95% CI 1.06–1.85). Although a higher frequency of the combination of minor alleles (A-A) in the subgroup of patients with visual ischemic complications compared with the combination of both major alleles (G-G; p = 0.029) or with the other allelic combinations (p = 0.035) was found, logistic regression analysis showed that this association was no longer significant after adjustment for potential confounding factors (A-A vs G-G: OR 2.10, 95% CI 0.88–5.04, p = 0.096). Conclusion. Our results support a potential influence of the rs3790567 IL12RB2 polymorphism in the pathogenesis of GCA.

Role of the CCR5/Δ32CCR5 polymorphism in biopsy-proven giant cell arteritis

To further explore the potential role of chemokines in giant cell arteritis (GCA), we have studied whether the CCR5/Δ32CCR5 polymorphism is implicated in the susceptibility to the disease and its specific features. A total of 352 Spanish patients with biopsy-proven GCA and 479 matched controls were assessed. DNA was obtained from peripheral blood. Samples were genotyped by PCR with specific primers spanning the 32-bp deletion region. No statistically significant difference in the Δ32CCR5 allele frequency between GCA patients (6.1%) and controls (6.8%) was observed (p = 0.58). This was also the case when the CCR5 /Δ32CCR5 genotype distribution was assessed (p = 0.49). The Δ32CCR5 allele frequency did not differ between patients with or without specific manifestations of the disease, such as polymyalgia rheumatica, visual ischemic manifestations, or irreversible occlusive disease. Hence, our results do not support a potential influence of Δ32CCR5 in the susceptibility to or clinical spectrum of GCA.

Influence of CD40 rs1883832 Polymorphism in Susceptibility to and Clinical Manifestations of Biopsy-proven Giant Cell Arteritis

Objective. To assess the potential association between CD40 rs1883832 polymorphism and biopsy-proven giant cell arteritis (GCA). We also studied the influence of the polymorphism on phenotypic expression of this vasculitis, in particular the development of visual ischemic manifestations. Methods. Three hundred five Spanish patients with biopsy-proven GCA and 788 matched controls were assessed. DNA from patients and controls was obtained from peripheral blood. Samples were genotyped for the CD40 rs1883832 C/T polymorphism using a predesigned TaqMan allele discrimination assay and by polymerase chain reaction amplification. Results. Patients with GCA showed a trend toward a higher frequency of the minor allele homozygote of rs1883832 (TT) compared to healthy controls (12.1% vs 8.3%, respectively; p = 0.05, OR 1.54, 95% CI 0.98–2.40). Also, a marginally significant increased frequency of the minor allele T was observed in patients with GCA who had visual ischemic manifestations (36.9%) compared to those without visual ischemic manifestations (27.7%; p = 0.04, OR 1.53, 95% CI 0.99–2.34). In this regard, patients with GCA carrying the minor allele T (either TT or TC) experienced visual ischemic manifestations more commonly than those carrying the CC genotype (58.5% vs 44.2%; p = 0.04, OR 1.78, 95% CI 0.99–3.22). Conclusion. Our results suggest a potential implication of the CD40 rs1883832 C/T polymorphism in susceptibility to visual ischemic manifestations in individuals with biopsy-proven GCA.

Lack of Association Between TRAF1/C5 Gene Polymorphisms and Biopsy-proven Giant Cell Arteritis

Objective. A novel association with a 100-kb region on chromosome 9 that contains the tumor necrosis factor receptor-associated factor 1 (TRAF1) and C5 genes has been observed in some autoimmune rheumatic diseases, in particular in rheumatoid arthritis. We analyzed the influence of 2 single-nucleotide polymorphisms (SNP) from the TRAF1/C5 region in susceptibility to giant cell arteritis (GCA). Methods. We assessed 220 patients with biopsy-proven GCA and 410 matched controls. DNA from patients and controls was obtained from peripheral blood. Samples were genotyped for the rs10818488 and rs2900180 TRAF1/C5 gene polymorphisms by polymerase chain reaction, using a predesigned TaqMan allele discrimination assay. Results. A genotyping rate of 95% was achieved in this series of GCA. No significant differences in the genotype distribution between GCA patients and controls were found for the 2 SNP. GCA patients exhibited a reduced frequency of TRAF1/C5 AA homozygosity (7.6%) compared to controls (12.7%) but the difference was only marginally significant (OR 0.58, 95% CI 0.30–1.11, p = 0.07). The frequency of minor allele T of TRAF1/C5 rs2900180 was also slightly reduced in patients (24.3%) compared to controls (27.8%) (p = 0.19). No significant differences were observed when patients were stratified according to the presence of specific clinical disease features. Conclusion. Our results showed no influence of rs10818488 and rs2900180 TRAF1/C5 gene polymorphisms in susceptibility to and clinical expression of GCA.

Role of the C8orf13-BLK region in biopsy-proven giant cell arteritis.

Giant cell arteritis (GCA) is a complex polygenic disease in which more than one genetic locus is likely to contribute to disease susceptibility and clinical expression. In the present study, we have analyzed for first time the implication of rs13277113 and rs2736340 variants from the C8orf13-BLK gene region in the susceptibility to GCA. A total of 220 biopsy-proven GCA patients and 486 matched controls were assessed. DNA from patients and controls was obtained from peripheral blood. Samples were genotyped for the C8orf13-BLK region rs13277113 and rs2736340 using a predesigned TaqMan allele discrimination assay. No significant differences in the genotype distribution between GCA patients and controls for the rs13277113 and rs2736340 C8orf13-BLK gene variants were found. GCA patients were also stratified according to the presence of specific clinical features of the disease. In this regard, the allele A of the rs13277113 variant was overrepresented in patients with severe ischemic manifestations compared with patients without severe ischemic manifestations (p = 0.04; OR =1.65; 95% CI = 0.99-2.78). In conclusion, our results do not support a major implication of the C8orf13-BLK gene region in susceptibility to GCA. However, a potential implication of the rs13277113 variant in the development of severe ischemic complications may exist.