Identification of a genetic variant for joint damage progression in autoantibody-positive rheumatoid arthritis.

BACKGROUND: Joint destruction is a hallmark of autoantibody-positive rheumatoid arthritis (RA), though the severity is highly variable between patients. The processes underlying these interindividual differences are incompletely understood. METHODS: We performed a genome-wide association study on the radiological progression rate in 384 autoantibody-positive patients with RA. In stage-II 1557 X-rays of 301 Dutch autoantibody-positive patients with RA were studied and in stage-III 861 X-rays of 742 North American autoantibody-positive patients with RA. Sperm-Associated Antigen 16 (SPAG16) expression in RA synovium and fibroblast-like synoviocytes (FLS) was examined using Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR) and immunohistochemistry. FLS secrete metalloproteinases that degrade cartilage and bone. SPAG16 genotypes were related to matrix metalloproteinase (MMP)-3 and MMP-1 expression by FLS in vitro and MMP-3 production ex vivo. RESULTS: A cluster of single nucleotide polymorphisms (SNPs) at 2q34, located at SPAG16, associated with the radiological progression rate; rs7607479 reached genome-wide significance. A protective role of rs7607479 was replicated in European and North American patients with RA. Per minor allele, patients had a 0.78-fold (95% CI 0.67 to 0.91) progression rate over 7 years. mRNA and protein expression of SPAG16 in RA synovium and FLS was verified. FLS carrying the minor allele secreted less MMP-3 (p=1.60×10(-2)). Furthermore, patients with RA carrying the minor allele had lower serum levels of MMP-3 (p=4.28×10(-2)). In a multivariate analysis on rs7607479 and MMP-3, only MMP-3 associated with progression (p=2.77×10(-4)), suggesting that the association between SPAG16-rs7607479 and joint damage is mediated via an effect on MMP-3 secretion. CONCLUSIONS: Genetic and functional analyses indicate that SPAG16 influences MMP-3 regulation and protects against joint destruction in autoantibody-positive RA. These findings could enhance risk stratification in autoantibody-positive RA.

Reasons for medical help-seeking behaviour of patients with recent-onset arthralgia.

OBJECTIVE: Patient delay in seeking medical help may cause suboptimal use of the therapeutic window in rheumatoid arthritis. We aimed to assess the motivations and the urgency with which patients with arthralgia seek medical help. METHODS: 612 patients with arthralgia-visiting two Dutch Early Arthritis Recognition Clinics-were studied. Patients filled out a questionnaire with questions on their symptoms and their reasons for seeking medical help. Comparisons were made for patients with short or prolonged patient delay, patients with and without arthritis, age and gender. RESULTS: The median symptom duration was 4 weeks. A prolonged delay in seeking help was associated with a gradual onset of symptoms (78%) and the perception that symptoms would not be serious or would go away (16% and 48%, respectively). Arthralgia patients who promptly sought medical help more often had an acute onset of symptoms and more frequently reported impairments at work or in daily functioning than patients who postponed seeking help (all p<0.005). Patients with and without arthritis generally had similar reasons for seeking help. The proportion of patients who had a prolonged patient delay was comparable between male and female subjects and between age categories. Particularly younger patients postponed seeking help because they thought their symptoms would disappear spontaneously. CONCLUSIONS: This large-scale study observed several reasons and symptom characteristics influencing the help-seeking behaviour of persons with arthralgia. These data can be helpful to define strategies aiming at early identification of arthritis.

Genetic studies on components of the Wnt signalling pathway and the severity of joint destruction in rheumatoid arthritis.

BACKGROUND: Progression of joint destruction in rheumatoid arthritis (RA) is partly heritable; knowledge of genetic factors may increase our understanding of the mechanisms underlying joint destruction. The activity of the Wnt/ß-catenin pathway influences osteoblast differentiation. Dickkopf-1 (Dkk-1) and sclerostin (Sost) are negative regulators and lipoprotein receptor-related protein-5 (LRP-5) and Kremen-1 are transmembrane receptors involved in this pathway. OBJECTIVE: To study variants in the genes encoding these proteins in relation to progression of joint destruction. METHODS: 1418 patients with RA of four cohorts with 4885 sets of hands and feet x-rays were studied. Explorative analyses were performed on 600 patients with RA from Leiden on single nucleotide polymorphisms (SNPs) tagging Dkk-1, Sost, Kremen-1 and LRP-5. SNPs significantly associating with joint damage progression were subsequently genotyped in cohorts from Groningen (NL), Sheffield (UK) and Lund (Sweden). Data were summarised in meta-analyses. Serum levels of functional Dkk-1 and sclerostin were measured and studied in relation to genotypes. RESULTS: In the first cohort, six Dkk-1, three Sost, one Kremen-1 and 10 LRP-5 SNPs were significantly associated with radiological progression of joint destruction. Three Dkk-1 SNPs were associated significantly with progression of joint damage in the meta-analysis, also after correction for multiple testing (rs1896368, rs1896367 and rs1528873). Two Sost SNPs tended to significance (rs4792909 and rs6503475, p=0.07 after false discovery rate correction). Gene-gene interactions between SNPs on Dkk-1 and Sost were seen. Serum levels of Dkk-1 were significantly correlated with the genotypes in rs1896368 (p=0.02). CONCLUSIONS: Patients with RA carrying risk alleles of genetic variants in Dkk-1 have higher serum levels of functional Dkk-1 and more progressive joint destruction over time.

Loss of metacarpal bone density predicts RA development in recent-onset arthritis.

OBJECTIVE: Serum samples taken before the onset of RA suggest that one of the first features of RA is BMD loss. We determined the ability of radiographic BMD loss to predict RA development and arthritis persistency in patients with early undifferentiated arthritis (UA). METHODS: Five hundred and seventeen patients with early UA, included in the Leiden Early Arthritis Clinic, were assessed. Of these, 101 had hand radiographs made at first visit as well as after 6 months. BMD loss was measured using digital X-ray radiogrammetry (DXR) online. The outcome measures fulfilled the 1987 ACR criteria for RA after 1 year and arthritis persistency during a mean follow-up of 7 years. Additionally, it was assessed whether BMD measurements improved predictions compared with a validated prediction rule. RESULTS: A total of 53.8% of UA patients developed RA and 67.5% had persistent disease after 7 years follow-up. Highly elevated BMD loss (≥2.5 mg/cm2/month) was present in 16.3% of patients and associated with RA development [odds ratio (OR) 6.1, 95% CI 1.2, 29.2, positive predictive value (PPV) 85%, negative predictive value (NPV) 52%, sensitivity 26%, specificity 95%]. BMD loss may have an independent effect of anti-CCP when tested in a logistic regression analysis (OR 4.1, 95% CI 0.8, 21.2), although the CI is large. All UA patients that were unclassified with the prediction rule and had highly elevated BMD loss progressed to RA. BMD loss was not significantly associated with arthritis persistency (HR = 0.56, 95% CI 0.14, 2.29). CONCLUSION: Present data suggest that BMD loss predicts RA development. These findings need to be verified in larger studies.

Predicting arthritis outcomes--what can be learned from the Leiden Early Arthritis Clinic?

OBJECTIVES: In order to allow personalized medicine, adequate prediction of disease outcome is required. In early undifferentiated arthritis (UA), prediction of the development of RA is crucial, and in case of RA predicting the severity of the disease course may guide individualized treatment decisions. METHODS: A total of 570 UA patients and 676 RA patients included in the Leiden Early Arthritis Clinic cohort were studied for baseline characteristics. The disease outcomes studied were fulfillment of the 1987 ACR-RA criteria and arthritis persistence in UA patients and the rate of radiological joint destruction and achieving sustained DMARD-free remission in RA patients. RESULTS: Predictive factors for fulfillment of the 1987 ACR-RA criteria and for persistent arthritis in UA were largely similar. Risk factors for a severe rate of joint destruction were: older age (P<0.001); male gender (P<0.001); longer symptom duration at first visit (P=0.048), involvement of lower extremities (P<0.001); BMI (P<0.001); high acute phase reactants, presence of IgM-RF (P<0.001); anti-CCP2 antibodies (P<0.001); anti-modified citrullinated vimentin antibodies (P<0.001) and HLA-DRB1 shared epitope alleles (P=0.001). A high BMI was associated with a lower rate of joint destruction but with a higher risk of disease persistence. The proportion of variance in joint destruction explained was 32% CONCLUSION: Predictors for RA development, previously used to develop a prediction rule in UA patients, are largely similar to predictors for arthritis persistency. Only part of the joint destruction level in RA is explained by the currently known risk factors. New factors need to be identified in order to guide pharmaceutical intervention at the level of individual RA patients.

Genetic Factors for the Severity of ACPA-negative Rheumatoid Arthritis in 2 Cohorts of Early Disease: A Genome-wide Study.

OBJECTIVE: Rheumatoid arthritis (RA) that is negative for anticitrullinated protein antibodies (ACPA) is a subentity of RA, characterized by less severe disease. At the individual level, however, considerable differences in the severity of joint destruction occur. We performed a study on genetic factors underlying the differences in joint destruction in ACPA-negative patients. METHODS: A genome-wide association study was done with 262 ACPA-negative patients with early RA included in the Leiden Early Arthritis Clinic and related to radiographic joint destruction over 7 years. Significant single-nucleotide polymorphisms (SNP) were evaluated for association with progression of radiographic joint destruction in 253 ACPA-negative patients with early RA included in the Better Anti-Rheumatic Farmaco Therapy (BARFOT) study. According to the Bonferroni correction of the number of tested SNP, the threshold for significance was p < 2 × 10(-7) in phase 1 and 0.0045 in phase 2. In both cohorts, joint destruction was measured by Sharp/van der Heijde method with good reproducibility. RESULTS: Thirty-three SNP associated with severity of joint destruction (p < 2 × 10(-7)) in phase 1. In phase 2, rs2833522 (p = 0.0049) showed borderline significance. A combined analysis of both the Leiden and BARFOT datasets of rs2833522 confirmed this association with joint destruction (p = 3.57 × 10(-9)); the minor allele (A) associated with more severe damage (for instance, after 7 yrs followup, patients carrying AA had 1.22 times more joint damage compared to patients carrying AG and 1.50 times more joint damage than patients carrying GG). In silico analysis using the ENCODE and Ensembl databases showed presence of H3K4me3 histone mark, transcription factors, and long noncoding RNA in the region of rs2833522, an intergenic SNP located between HUNK and SCAF4. CONCLUSION: Rs2833522 might be associated with the severity of joint destruction in ACPA-negative RA.

A genetic variant in osteoprotegerin is associated with progression of joint destruction in rheumatoid arthritis.

INTRODUCTION: Progression of joint destruction in rheumatoid arthritis (RA) is partly heritably; 45 to 58% of the variance in joint destruction is estimated to be explained by genetic factors. The binding of RANKL (Receptor Activator for Nuclear Factor κ B Ligand) to RANK results in the activation of TRAF6 (tumor necrosis factor (TNF) receptor associated factor-6), and osteoclast formation ultimately leading to enhanced bone resorption. This bone resorption is inhibited by osteoprotegerin (OPG) which prevents RANKL-RANK interactions. The OPG/RANK/RANKL/TRAF6 pathway plays an important role in bone remodeling. Therefore, we investigated whether genetic variants in OPG, RANK, RANKL and TRAF6 are associated with the rate of joint destruction in RA. METHODS: 1,418 patients with 4,885 X-rays of hands and feet derived from four independent data-sets were studied. In each data-set the relative increase of the progression rate per year in the presence of a genotype was assessed. First, explorative analyses were performed on 600 RA-patients from Leiden. 109 SNPs, tagging OPG, RANK, RANKL and TRAF6, were tested. Single nucleotide polymorphisms (SNPs) significantly associated in phase-1 were genotyped in data-sets from Groningen (Netherlands), Sheffield (United Kingdom) and Lund (Switzerland). Data were summarized in an inverse weighted variance meta-analysis. Bonferonni correction for multiple testing was applied. RESULTS: We found that 33 SNPs were significantly associated with the rate of joint destruction in phase-1. In phase-2, six SNPs in OPG and four SNPs in RANK were associated with progression of joint destruction with P-value <0.05. In the meta-analyses of all four data-sets, RA-patients with the minor allele of OPG-rs1485305 expressed higher rates of joint destruction compared to patients without these risk variants (P = 2.35x10-4). This variant was also significant after Bonferroni correction. CONCLUSIONS: These results indicate that a genetic variant in OPG is associated with a more severe rate of joint destruction in RA.

Associations between APOE genotypes and disease susceptibility, joint damage and lipid levels in patients with rheumatoid arthritis.

OBJECTIVE: Apolipoprotein E (APOE) genotypes are associated with cardiovascular disease (CVD) and lipid levels. In rheumatoid arthritis (RA), an association has been found with disease activity. We examined the associations between APOE genotypes and disease susceptibility and markers of disease severity in RA, including radiographic joint damage, inflammatory markers, lipid levels and cardiovascular markers. METHOD: A Norwegian cohort of 945 RA patients and 988 controls were genotyped for two APOE polymorphisms. We examined longitudinal associations between APOE genotypes and C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) as well as hand radiographs (van der Heijde Sharp Score(SHS)) in 207 patients with 10 year longitudinal data. Lipid levels, cardiovascular markers and history of CVD were compared across genotypes in a cross sectional study of 136 patients. Longitudinal radiological data of cohorts from Lund and Leiden were available for replication. (N = 935, with 4799 radiographs). RESULTS: In the Norwegian cohort, associations between APOE genotypes and total cholesterol (TC) and low-density lipoproteins (LDL) were observed (ε2 < ε3/ε3 < ε4, p = 0.03 and p = 0.02, respectively). No association was present for acute phase reactant or CVD markers, but a longitudinal linear association between APOE genotypes and radiographic joint damage was observed (p = 0.007). No association between APOE genotypes and the severity of joint destruction was observed in the Lund and Leiden cohorts, and a meta- analysis combining all data was negative. CONCLUSION: APOE genotypes are associated with lipid levels in patients with RA, and may contribute to dyslipidemia in some patients. APOE genotypes are not consistently associated with markers of inflammation or joint destruction in RA.

Can anti-cyclic citrullinated peptide antibody-negative RA be subdivided into clinical subphenotypes?

INTRODUCTION: Studies investigating genetic risk factors for susceptibility to rheumatoid arthritis (RA) studied anti-citrullinated peptide antibody (CCP)-positive RA more frequently than anti-CCP-negative RA. One of the reasons for this is the perception that anti-CCP-negative RA may include patients that fulfilled criteria for RA but belong to a wide range of diagnoses. We aimed to evaluate the validity of this notion and explored whether clinical subphenotypes can be discerned within anti-CCP-negative RA. METHODS: The 318 patients with anti-CCP-negative RA (1987 ACR criteria), included in the Leiden Early Arthritis Clinic between 1993 and 2006, were studied for baseline characteristics and radiologic progression data during a mean follow-up of 5 years. Grouping was studied both at variable and patient levels. Principal components analysis and partial least-squares regression were applied to study for clustering of variables. A cluster analysis was performed to look for clustering of patients. RESULTS: The simultaneous presence of patient characteristics at disease presentation was observed for several groups; however, the three largest groups of patients' characteristics explained only 26.5% of the total variance. Plotting the contribution of each patient to these three groups did not reveal clustering of patients. Comparable observations were made when data on progression of joint destruction were studied in relation to baseline clinical data. A cluster analysis, evaluating whether patients resemble each other, revealed no grouping of patients. Altogether, no clinically distinguishable subphenotypes were observed. CONCLUSIONS: The current data provide evidence that, for risk-factor studies, anti-CCP-negative RA patients can be studied as one group.