Tore K. Kvien

Association analysis of the 1858C>T polymorphism in the PTPN22 gene in juvenile idiopathic arthritis and other autoimmune diseases.

A functional single nucleotide polymorphism, 1858C>T, in the PTPN22 gene, encoding a tyrosine phosphatase, has been reported to be associated with type I diabetes and some other autoimmune diseases. To further investigate whether this polymorphism may be a general susceptibility factor for autoimmunity, we performed an association study in five different autoimmune diseases, three previously not tested. We found an association with juvenile idiopathic arthritis (OR=1.41; P=0.04), not previously reported, and a tendency for an association with coeliac disease (OR=1.35; P=0.08). In primary sclerosing cholangitis, no association was observed (OR=0.95; P=0.8). Furthermore, we confirmed the increased risk in rheumatoid arthritis (OR=1.58; P=0.001), but could not find support for an association with systemic lupus erythematosus (OR=0.94; P=0.8). Altogether, we have provided further evidence of an association between autoimmune diseases and the 1858C>T polymorphism in PTPN22.

A coding polymorphism in NALP1 confers risk for autoimmune Addison's disease and type 1 diabetes.

Variants in the gene encoding NACHT leucine-rich-repeat protein 1 (NALP1), an important molecule in innate immunity, have recently been shown to confer risk for vitiligo and associated autoimmunity. We hypothesized that sequence variants in this gene may be involved in susceptibility to a wider spectrum of autoimmune diseases. Investigating large patient cohorts from six different autoimmune diseases, that is autoimmune Addisons disease (n=333), type 1 diabetes (n=1086), multiple sclerosis (n=502), rheumatoid arthritis (n=945), systemic lupus erythematosus (n=156) and juvenile idiopathic arthritis (n=505), against 3273 healthy controls, we analyzed four single nucleotide polymorphisms (SNPs) in NALP1. The major allele of the coding SNP rs12150220 revealed significant association with autoimmune Addisons disease compared with controls (OR=1.25, 95% CI: 1.06–1.49, P=0.007), and with type 1 diabetes (OR=1.15, 95% CI: 1.04–1.27, P=0.005). Trends toward the same associations were seen in rheumatoid arthritis, systemic lupus erythematosus and, although less obvious, multiple sclerosis. Patients with juvenile idiopathic arthritis did not show association with NALP1 gene variants. The results indicate that NALP1 and the innate immune system may be implicated in the pathogenesis of many autoimmune disorders, particularly organ-specific autoimmune diseases.

Association analysis of the interleukin 17A gene in Caucasian rheumatoid arthritis patients from Norway and New Zealand

OBJECTIVEnElevated levels of IL-17A have been detected in the inflamed synovium of RA patients, and murine arthritis models deficient in IL17A have shown reduced inflammation. Our aim was to investigate IL17A as a candidate gene for RA, and to assess correlations between risk variants and disease phenotypes.nnnMETHODSnFive single nucleotide polymorphisms (SNPs) were selected to tag the genetic variability of the IL17A region and were genotyped by TaqMan technology on 950 RA cases and 933 random controls from Norway. Associations to progression of radiographic damage and presence of autoantibodies were examined in a 10-yr follow-up cohort of early RA. In addition, 580 RA patients and 504 controls from New Zealand were used as a replication data set.nnnRESULTSnA weak association between RA and the promoter SNP rs2275913 [odds ratio (OR) = 1.17; 95% CI 1.02, 1.34; P = 0.02] was found in the Norwegian population. The association was also evident at the genotype level where it indicated a recessive model. The allelic association was not replicated in the RA cohort from New Zealand (OR = 0.96; 95% CI 0.81, 1.16; P = 0.69). However, combined analysis suggested a weak recessive association (OR = 1.19; 95% CI 1.02, 1.37; P = 0.02). No significant associations were observed with radiographic progression, anti-cyclic citrullinated peptide or IgM-RF.nnnCONCLUSIONSnModest evidence of an association with IL17A in Norwegian RA patients was observed. Although, our findings were not replicated in an independent RA material from New Zealand, a significant common risk estimate indicated that IL17A warrants further investigation in RA.

Lipids, myocardial infarction and ischaemic stroke in patients with rheumatoid arthritis in the Apolipoprotein-related Mortality RISk (AMORIS) Study

Objectives To examine the rates of acute myocardial infarction (AMI) and ischaemic stroke (IS) and to examine the predictive value of total cholesterol (TC) and triglycerides (TG) for AMI and IS in patients with rheumatoid arthritis (RA) and people without RA. Methods In the Apolipoprotein MOrtality RISk (AMORIS) Study 480 406 people (including 1779 with RA, of whom 214 had an AMI and 165 an IS) were followed for 11.8 (range 7–17) years. Cox regression analysis was used to calculate HR per SD increase in TC or TG with 95% CI. All values were adjusted for age, diabetes and hypertension. Results The levels of TC and TG were significantly lower in patients with RA than in people without RA. Despite this, the rate of AMI and IS per 1000 years was at least 1.6 times higher in RA than non-RA. TC was nearly significantly predictive for AMI (HR/SD 1.13 (95% CI 0.99 to 1.29), p=0.07) and significantly predictive for future IS in RA (HR/SD 1.20 (95% CI 1.03 to 1.40), p=0.02). TG had no relationship to development of AMI (1.07, 0.94 to 1.21, p=0.29), but was weakly related to IS (1.13, 0.99 to 1.27, p=0.06). In contrast, both TC and TG were significant predictors of AMI and IS in people without RA. Conclusions Patients with RA had 1.6 times higher rate of AMI and IS than people without RA. TC and TG were significant predictors of AMI and IS in people without RA, whereas the predictive value in RA was not consistent.

Intensive lipid lowering in patients with rheumatoid arthritis and previous myocardial infarction: an explorative analysis from the incremental decrease in endpoints through aggressive lipid lowering (IDEAL) trial

OBJECTIVESnDocumentation on secondary prevention with statins in RA patients with coronary heart disease (CHD) is limited, despite the increased risk of CHD in RA. Our objective was to describe the effect of statin treatment on lipid levels and cardiovascular disease (CVD) events in patients with RA who participated in the incremental decrease in endpoints through aggressive lipid lowering (IDEAL) study.nnnMETHODSnPatients with previous myocardial infarction (MI) were randomly assigned to atorvastatin 80u2009mg daily or simvastatin 20-40u2009mg daily and followed for 4.8 years. We focused on changes in lipid levels in the current exploratory analyses and used the composite secondary endpoint in the IDEAL study: any CVD event. Out of the 8888 patients in the IDEAL study, 87 had RA.nnnRESULTSnRA patients had significantly lower baseline levels of total- and low-density lipoprotein (LDL) cholesterol than patients without RA; 4.8u2009+u20091.0 vs 5.1u2009+u20091.0 (Pu2009=u20090.023) and 2.9u2009+u20090.9 vs 3.1u2009+u20090.9u2009mmol/l (Pu2009=u20090.034) for total cholesterol and LDL, respectively. The lipid reductions with either simvastatin or atorvastatin were comparable. Cardiovascular events occurred in 23/87 (26.4%) of the RA patients compared with 2523/8801 (28.7%; Pu2009=u20090.70) in the general IDEAL population. The occurrence of these events was not related to the duration of RA, age, gender or treatment assignment.nnnCONCLUSIONnPatients with RA and previous MI had comparable lipid-lowering effect and similar rates of cardiovascular events as those without RA, although the RA patients had lower baseline cholesterol levels than patients without RA.

Rosuvastatin‐Induced Carotid Plaque Regression in Patients With Inflammatory Joint Diseases: The Rosuvastatin in Rheumatoid Arthritis, Ankylosing Spondylitis and Other Inflammatory Joint Diseases Study

Patients with rheumatoid arthritis (RA) and carotid artery plaques have an increased risk of acute coronary syndromes. Statin treatment with the goal of achieving a low‐density lipoprotein (LDL) cholesterol level of ≤1.8 mmoles/liter (≤70 mg/dl) is recommended for individuals in the general population who have carotid plaques. The aim of the ROsuvastatin in Rheumatoid Arthritis, Ankylosing Spondylitis and other inflammatory joint diseases (RORA‐AS) study was to evaluate the effect of 18 months of intensive lipid‐lowering treatment with rosuvastatin with regard to change in carotid plaque height.

Interferon regulatory factor 5 gene polymorphism confers risk to several rheumatic diseases and correlates with expression of alternative thymic transcripts

OBJECTIVESnPolymorphisms in genes related to the IFN pathway were investigated for susceptibility to rheumatic diseases and correlation with gene expression in thymus.nnnMETHODSnForty-five polymorphisms were genotyped in Norwegian patients with RA (nu2009=u2009518), JIA (nu2009=u2009440), SLE (nu2009=u2009154) and healthy controls (nu2009=u2009756). Forty-two thymic samples were used for gene expression analysis. Six hundred and fifty SLE patients and 737 healthy controls from Spain were available for replication.nnnRESULTSnWe found a novel association between interferon regulatory factor 5 (IRF5), rs2004640 and JIA, in particular with the polyarthritis RF-negative patients [odds ratio (OR)u2009=u20091.60; 95% confidence interval (CI) 1.17, 2.20; Pu2009=u20090.003]. Also, we confirmed the associations between rs2004640 and SLE (ORu2009=u20091.95; 95% CI 1.50, 2.53; Pu2009=u20093.75u2009×u200910(-7)), which was further strengthened in a meta-analysis (ORu2009=u20091.44; 95% CI 1.36, 1.52; Pu2009=u20092.11u2009×u200910(-37)). Suggestive evidence of association between rs2004640 and RA was found in the Norwegian discovery cohort (ORu2009=u20091.19; 95% CI 1.02, 1.40; Pu2009=u20090.029) and strengthened in a meta-analysis (ORu2009=u20091.11; 95% CI 1.05, 1.18; Pu2009=u20090.00028). Expression levels of exon 1B IRF5 transcripts were dependent on the presence of the rs2004640 T risk allele in thymic tissue, while exon 1A transcript levels correlated with IRF5 promoter CGGGG-indel variants.nnnCONCLUSIONnThe IFN pathway gene, IRF5, is a common susceptibility factor for several rheumatic and autoimmune diseases, and risk variants are correlated with expression of alternative IRF5 transcripts in thymus implying a regulatory role.

CIITA gene variants are associated with rheumatoid arthritis in Scandinavian populations.

Expression of the major autoimmune risk loci DRB1 and DQB1 is regulated by the class II MHC (major histocompatibility complex) transactivator (CIITA), making the CIITA gene a strong autoimmune risk locus candidate. A CIITA promoter single-nucleotide polymorphism (SNP), rs3087456 (-168u2009A/G), has indeed been associated with several autoimmune diseases, including rheumatoid arthritis (RA). Recently, an intronic SNP rs8048002 has been suggested as a better susceptibility marker in Addison’s disease. Therefore, we tested both SNPs in a panel of autoimmune diseases, consisting of Norwegian patients with RA (n=819), juvenile idiopathic arthritis (JIA; n=524), or type 1 diabetes (T1D; n=1211), and 2149 controls. We also included an independent Swedish RA cohort (n=2503) and controls (n=1416). Both rs3087456 and rs8048002 were significantly associated with RA (combined Norwegian and Swedish patients Pcorrected=0.012 and Pcorrected=0.0016, respectively), but not with JIA or T1D. Meta-analysis of 16 RA cohorts confirmed rs3087456 with only marginal significance (P=0.016). However, results were stronger in the Scandinavian subgroup (4 cohorts, P=3.8 × 10−4), indicating a population-dependent effect. A similar pattern was observed in a meta-analysis of rs8048002. Our results support involvement of CIITA in RA, but imply that this is population dependent and that the aetiological variant is yet to be discovered.

HLA-C alleles confer risk for anti-citrullinated peptide antibody-positive rheumatoid arthritis independent of HLA-DRB1 alleles

OBJECTIVEnThe MHC exerts the greatest contribution to RA susceptibility, where certain HLA-DRB1 alleles confer the greatest risk. Interestingly, there is evidence for more risk factors in the MHC with regions surrounding the HLA class I loci, but whether these antigen-presenting loci could be causal risk variants has not been directly investigated. In this study we investigate the HLA association by direct genotyping of the HLA loci.nnnMETHODSnNine hundred and fifty RA patients and 933 healthy controls were genotyped for HLA-A, -B and -C. Eleven single-nucleotide polymorphisms (SNPs) and one insertion/deletion in the MHC were also included. Conditional logistic regression analyses were performed separately in ACPA-positive and -negative RA to identify the strongest susceptibility locus and additional risk loci.nnnRESULTSnIn ACPA-positive RA, the most significantly associated locus was HLA-DRB1 (P = 1.58 × 10(-54)), with SE alleles being predisposing. After controlling for HLA-DRB1, the HLA-C locus was found to confer susceptibility (P = 2.32 × 10(-9)), particularly, the HLA-C*03 allele. Also, in ACPA-negative RA, HLA-DRB1 was the most significant locus (P = 7.22 × 10(-9)), but with other risk alleles (particularly DRB1*03). A possible independent involvement of HLA-C was also observed for ACPA-negative RA (P = 0.02).nnnCONCLUSIONnHLA-DRB1 was the major MHC risk locus in both ACPA-positive and ACPA-negative RA, but with allelic risk heterogeneity. Joint analyses of the HLA class I loci together with previously proposed SNP associations pointed at HLA-C as a second susceptibility locus in ACPA-positive RA.

Association analysis of the CCL3L1 copy number locus by paralogue ratio test in Norwegian rheumatoid arthritis patients and healthy controls

Genotyping of multiallelic copy number variants (CNVs) is technically difficult and can lead to inaccurate conclusions. This is reflected by inconsistent results published for the CNV C-C chemokine ligand 3-like 1 (CCL3L1) and its contribution to rheumatoid arthritis (RA) susceptibility. In order to draw robust conclusions about CCL3L1 involvement in RA, we have performed association analysis (CNVtools) using genotyping by the paralogue ratio test of a Norwegian RA case–control material (N=1877). We also analyzed the associations after stratification for anti-citrullinated peptide antibody (ACPA) status. Clear clusters representing specific copy number classes were evident, but significant differential bias was observed resulting in a systematic trend toward slightly higher apparent copy number for cases relative to controls. Controlling for bias revealed no significant differences in copy number distribution either between all patients and controls, or after ACPA stratification. Our results do not support involvement of the CCL3L1 CNV in RA susceptibility.