Ana Márquez

Association of the STAT4 gene with increased susceptibility for some immune-mediated diseases.

OBJECTIVE The STAT4 gene encodes a transcription factor involved in the signaling pathways of several cytokines, including interleukin-12 (IL-12), the type I interferons, and IL-23. Recently, the association of a STAT4 haplotype marked by rs7574865 with rheumatoid arthritis (RA) and systemic lupus erythematosus was reported. The aim of this study was to investigate the role of this STAT4 tagging polymorphism in other immune-mediated diseases. METHODS The study group comprised 2,776 consecutively recruited Spanish individuals: 575 with RA, 440 with multiple sclerosis, 700 with inflammatory bowel disease, 311 with type 1 diabetes, and 723 ethnically matched healthy control subjects. The STAT4 polymorphism rs7574865 was genotyped using a predesigned TaqMan assay. Allele and genotype frequencies in patients and control subjects were compared by chi-square test. RESULTS The association of STAT4 polymorphism rs7574865 with RA was validated in patients of Spanish origin (for T versus G, P = 1.2 x 10(-6), odds ratio [OR] 1.59, 95% confidence interval [95% CI] 1.31-1.92), and the association was described for the first time in both clinical forms of inflammatory bowel disease, Crohns disease and ulcerative colitis (for T versus G, P = 0.006, OR 1.29, 95% CI 1.07-1.55), and in type 1 diabetes mellitus (for T versus G, P = 0.008, OR 1.36, 95% CI 1.07-1.71). In contrast, the genotypic distribution of this polymorphism showed no difference between patients with multiple sclerosis and healthy control subjects (for T versus G, P = 0.83, OR 1.02, 95% CI 0.82-1.28). CONCLUSION The STAT4 gene is emerging as a novel common risk factor for diverse complex diseases.

Role of the PXR gene locus in inflammatory bowel diseases

Background: The pregnane X receptor gene (PXR/NR1I2) has been recently associated with an increased risk for inflammatory bowel disease (IBD), although a subsequent case‐control study failed to replicate the original association in an independent population. This nuclear receptor regulates genes involved in the detoxification process in the liver and intestine, like ABCB1/MDR1. PXR expression was significantly reduced in the colon of patients with ulcerative colitis (UC), but remained unaffected in Crohns disease (CD) patients. Considering previous results, we aimed at investigating the impact of this locus on IBD predisposition in the Spanish population. Methods: Three PXR polymorphisms, including the 1 more strongly correlated with IBD risk in the initial study at −25385C/T (rs3814055) and the 6 haplotypes conformed by them, were analyzed in 365 UC and 331 CD patients and compared with 550 ethnically matched controls. Results: The overall haplotypic distribution showed a significant difference between UC and CD patients (P = 0.05; χ2 = 10.84). Among UC patients a significant difference was seen between those with extensive colitis and controls (P = 0.004; χ2 = 17.04), mainly due to the presence of a risk haplotype (rs3814055*T//rs6784598*C//rs2276707*C: P = 0.001; odds ratio [OR] = 1.66, 95% confidence interval [CI] 1.20–2.30). Patients with extensive UC carrying the −25385T allele showed increased susceptibility compared with left‐sided colitis patients and with healthy subjects. In patients with extensive UC a significantly different distribution of genotypes of the MDR1 G/A change located in intron 3 (rs3789243) was observed between carriers/noncarriers of the −25385T risk allele (P = 0.005). Conclusions: Our data seem to support the association of the PXR locus with extensive UC and the interaction between PXR and MDR1 genes. (Inflamm Bowel Dis 2007)

STAT3 locus in inflammatory bowel disease and multiple sclerosis susceptibility

STAT3 (signal transducer and activator of transcription 3) signaling is a critical component of Th17-dependent autoimmune processes. Genome-wide association studies (GWAS) have revealed the role of the STAT3 gene in inflammatory bowel disease (IBD) susceptibility, although confirmation in clinical subphenotypes is warranted. Mice with targeted deletion of Stat3 in T cells are resistant to experimental autoimmune encephalomyelitis, which is a multiple sclerosis (MS) model. Moreover, increased phosphorylated STAT3 was reported in T cells of patients evolving from clinically isolated syndrome to defined MS and in relapsing patients. These evidences led us to analyze the role of STAT3 in Crohns disease (CD), ulcerative colitis (UC) and MS risk. Polymorphisms in the STAT3 region (rs3809758/rs744166/rs1026916/rs12948909) were genotyped and the inferred haplotypes were subsequently analyzed in 860 IBD and 1540 MS Spanish patients and 1720 ethnically matched controls. The haplotype conformed by the risk alleles of each polymorphism was significantly associated with both clinical phenotypes of IBD (CD: P=0.005, odds ratio 1.25, 95% confidence interval 1.06–1.46; and UC: P=0.002, odds ratio 1.19, 95% confidence interval 1.02–1.38). No evidence of association was detected for MS. The originally described association of IBD with STAT3 polymorphisms is corroborated for the two clinical phenotypes, CD and UC, in an independent population. A major role of this gene in MS seems unlikely.

IL23R and IL12B polymorphisms in spanish IBD patients: No evidence of interaction

Background: Recent genomic surveys have identified IL23R and IL12B as susceptibility loci for inflammatory bowel disease (IBD). Our aim in the present study was to ascertain whether the IL23R and IL12B associations with IBD are also observed in our population, and to analyze possible genetic interactions between polymorphisms at IL12B and IL23R, ligand and receptor, respectively. Methods: In all, 707 IBD patients (344 with Crohns disease and 363 with ulcerative colitis) and 547 healthy controls from the same ethnic origin (Caucasian Spaniards) were included in the present study. Two single nucleotide polymorphisms (SNPs) in IL23R (rs7517847 and rs11209026) and 2 in IL12B (rs3212227 and rs6887695) genes were analyzed by TaqMan technology. Genetic frequencies were compared with a chi‐square test. Interaction between genes was analyzed by case‐only comparisons. Results: The data show an association of both IL23R SNPs with overall IBD (statistically stronger, rs7517847; odds ratio [OR] = 0.79, 95% confidence interval [CI]: 0.67–0.94, minor allele frequencies: 0.355 in IBD patients versus 0.410 in controls; P = 0.005), somewhat stronger in Crohns disease (OR = 0.74, 95% CI: 0.61–0.91) than in ulcerative colitis (OR = 0.84, 95% CI: 0.69–1.03). IL12B rs6887695 showed a weak association with IBD (OR = 1.24, 95% CI: 1.04–1.47, minor allele frequencies: 0.375 in IBD patients versus 0.326 in controls, P = 0.012), stronger in UC (OR = 1.31, 95% CI: 1.07–1.60, P = 0.007). No statistically significant differences were apparent when patients were stratified according to clinical characteristics. No interaction was observed between any of the polymorphisms studied at IL12B and IL23R. Conclusions: Our study confirms the association of IL23R and IL12B with IBD in the Spanish population, but no interaction between either loci could be detected.

Association of the macrophage migration inhibitory factor gene polymorphisms with inflammatory bowel disease

Macrophage migration inhibitory factor (MIF), an immunoregulatory cytokine that has pro-inflammatory, hormonal and enzymatic activities, has been found to be markedly increased in the serum of patients with inflammatory bowel disease (IBD).1,2 MIF-deficient mice failed to develop disease1 and blockage with anti-MIF antibody reduced disease activity.1,2 Finally, functional polymorphisms of the human MIF gene have been associated with increased susceptibility to inflammatory and autoimmune diseases.3 These findings prompted us to investigate the potential association of the functional MIF −173G/C and −794 (CATT)n gene variants with the susceptibility and clinical expression of IBD. We studied a case–control cohort (cohort 1) comprising 336 patients with Crohn’s disease and 287 patients with ulcerative colitis from south Spain and 361 controls from the same area. An additional cohort (cohort 2) was analysed, comprising 325 patients with Crohn’s disease, 347 patients with ulcerative colitis and 526 controls from Madrid. Table 1 shows the clinical characteristics …

Polymorphisms in the selenoprotein S gene: lack of association with autoimmune inflammatory diseases

BackgroundSelenoprotein S (SelS) protects the functional integrity of the endoplasmic reticulum against the deleterious effects of metabolic stress. SEPS1/SelS polymorphisms have been involved in the increased release of pro-inflammatory cytokines interleukin (IL)-1β, tumor necrosis factor (TNF)-α and IL-6 in macrophages. We aimed at investigating the role of the SEPS1 variants previously associated with higher plasma levels of these cytokines and of the SEPS1 haplotypes in the susceptibility to develop immune-mediated diseases characterized by an inflammatory component.ResultsSix polymorphisms distributed through the SEPS1 gene (rs11327127, rs28665122, rs4965814, rs12917258, rs4965373 and rs2101171) were genotyped in more than two thousand patients suffering from type 1 diabetes, rheumatoid arthritis or inflammatory bowel diseases and 550 healthy controls included in the case-control study.ConclusionLack of association of SEPS1 polymorphisms or haplotypes precludes a major role of this gene increasing predisposition to these inflammatory diseases.

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.

Role of ATG16L1 Thr300Ala polymorphism in inflammatory bowel disease: A Study in the Spanish population and a meta-analysis

Background: Thr300Ala polymorphism in ATG16L1 was reported as a susceptibility factor to Crohns disease (CD). Inconsistently replicated associations with ulcerative colitis (UC) and specifically with ileal CD were also reported. Our aims were: to replicate the ATG16L1 Thr300Ala association with inflammatory bowel disease (IBD) in the Spanish population, to perform a meta‐analysis to determine the risk conferred to the different IBD subgroups, and to test for the interaction with CARD15 or IL23R risk loci. Methods: Thr300Ala (rs2241880) single nucleotide polymorphism (SNP) was genotyped in 712 IBD patients and 745 controls by TaqMan technology. Genetic frequencies were compared with chi‐square tests. Our findings were pooled in a meta‐analysis. Results: In Spain, we observed an association of rs2241880 with CD (P = 0.008; odds ratio [OR, 95% confidence interval, CI] = 1.28 [1.06–1.54]), but not with UC. No significant differences emerged when patients were stratified by clinical features. Similarly, the meta‐analysis demonstrated a significant association only with CD (P < 10−4; OR [95% CI] = 1.33 [1.28–1.38]). A significant difference between ileal CD patients and controls was observed, but heterogeneity was found in comparisons involving colonic CD patients and definite conclusions cannot be drawn. No interaction between rs2241880 and the established CARD15 or IL23R susceptibility variants was observed. Conclusions: The Thr300Ala polymorphism is associated with CD, regardless of the CARD15 or IL23R status, but not with UC. Stratification by clinical phenotypes did not show definitive results because of the existing heterogeneity among studies. (Inflamm Bowel Dis 2009;)

Lack of validation of genetic variants associated with anti-tumor necrosis factor therapy response in rheumatoid arthritis: a genome-wide association study replication and meta-analysis

IntroductionIn this study, our aim was to elucidate the role of four polymorphisms identified in a prior large genome-wide association study (GWAS) in which the investigators analyzed the responses of patients with rheumatoid arthritis (RA) to treatment with tumor necrosis factor inhibitors (TNFi). The authors of that study reported that the four genetic variants were significantly associated. However, none of the associations reached GWAS significance, and two subsequent studies failed to replicate these associations.MethodsThe four polymorphisms (rs12081765, rs1532269, rs17301249 and rs7305646) were genotyped in a total of 634 TNFi-treated RA patients of Spanish Caucasian origin. Four outcomes were evaluated: changes in the Disease Activity Score in 28 joints (DAS28) after 6 and 12 months of treatment and classification according to the European League Against Rheumatism (EULAR) response criteria at the same time points. Association with DAS28 changes was assessed by linear regression using an additive genetic model. Contingency tables of genotype and allele frequencies between EULAR responder and nonresponder patients were compared. In addition, we combined our data with those of previously reported studies in a meta-analysis including 2,998 RA patients.ResultsNone of the four genetic variants showed an association with response to TNFi in any of the four outcomes analyzed in our Spanish patients. In addition, only rs1532269 yielded a suggestive association (P = 0.0033) with the response to TNFi when available data from previous studies were combined in the meta-analysis.ConclusionOur data suggest that the rs12081765, rs1532269, rs17301249 and rs7305646 genetic variants do not have a role as genetic predictors of TNFi treatment outcomes.