D. P. C. de Rooy

Genetic variants in IL15 associate with progression of joint destruction in rheumatoid arthritis: a multicohort study

Background Interleukin (IL)-15 levels are increased in serum, synovium and bone marrow of patients with rheumatoid arthritis (RA). IL-15 influences both the innate and the adaptive immune response; its major role is activation and proliferation of T cells. There are also emerging data that IL-15 affects osteoclastogenesis. The authors investigated the association of genetic variants in IL15 with the rate of joint destruction in RA. Method 1418 patients with 4885 x-ray sets of both hands and feet of four independent data sets were studied. First, explorative analyses were performed on 600 patients with early RA enrolled in the Leiden Early Arthritis Clinic. Twenty-five single-nucleotide polymorphisms (SNPs) tagging IL-15 were tested. Second, SNPs with significant associations in the explorative phase were genotyped in data sets from Groningen, Sheffield and Lund. In each data set, the relative increase of the progression rate per year in the presence of a genotype was assessed. Subsequently, data were summarised in an inverse weighting meta-analysis. Results Five SNPs were significantly associated with rate of joint destruction in phase 1 and typed in the other data sets. Patients homozygous for rs7667746, rs7665842, rs2322182, rs6821171 and rs4371699 had respectively 0.94-, 1.04-, 1.09-, 1.09- and 1.09-fold rate of joint destruction compared to other patients (p=4.0×10−6, p=3.8×10−4, p=5.0×10−3, p=5.0×10−3 and p=9.4×10−3). Discussion Independent replication was not obtained, possibly due to insufficient power. Meta-analyses of all data sets combined resulted in significant results for four SNPs (rs7667746, p<0.001; rs7665842, p<0.001; rs4371699, p=0.01; rs6821171, p=0.01). These SNPs were also significant after correction for multiple testing. Conclusion Genetic variants in IL-15 are associated with progression of joint destruction in RA.

A genetic variant in the region of MMP-9 is associated with serum levels and progression of joint damage in rheumatoid arthritis

Objectives The severity of joint destruction is highly variable between rheumatoid arthritis (RA) patients. The majority of its heritability is still unexplained. Several autoimmune diseases share genetic risk variants that may also influence disease progression. We aimed to identify genetic risk factors for the severity of joint damage in RA by studying genetic susceptibility loci of several autoimmune diseases. Methods In phase 1, 3143 sets of x-rays of 646 Dutch RA patients taken over 7 years (Sharp van der Heijde (SHS) scored) were studied. Genotyping was done by Immunochip. Associations of single-nucleotide polymorphisms (SNPs) with minor allele frequency (MAF) >0.01 and joint destruction were analysed. In phase 2, 686 North American RA patients with 926 SHS-scored x-rays over 15 years of follow-up were evaluated. In both phases multiple testing corrections were done for the number of uncorrelated SNPs; the thresholds for significance were p<1.1×10−6 and p<0.0036. Matrix metalloproteinase 9 (MMP-9) levels were measured with ELISA in baseline serum samples. Results In phase 1, 109 SNPs associated significantly with joint destruction (p<1.1×10−6). Of these, 76 were located in the HLA region; the 33 non-HLA variants were studied in phase 2. Here two variants were associated with the severity of joint destruction: rs451066 on chromosome 14 (p=0.002, MAF=0.20) and rs11908352 on chromosome 20 (p=0.002, MAF=0.21). Rs11908352 is located near the gene encoding MMP-9. Serum levels of MMP-9 were significantly associated with the rs11908352 genotypes (p=0.007). Conclusions These data indicate that two loci that confer risk to other autoimmune diseases also affect the severity of joint destruction in RA. Rs11908352 may influence joint destruction via MMP-9 production.

Smoking as a risk factor for the radiological severity of rheumatoid arthritis: a study on six cohorts

Background Smoking is a risk factor for the development of anti -citrullinated protein antibodies (ACPA) positive rheumatoid arthritis (RA). Whether smoking predisposes to severe joint damage progression is not known, since deleterious, protective and neutral observations have been made. Objective To determine the effect of smoking on joint damage progression. Methods Smoking status was assessed in 3158 RA patients included in six cohorts (Leiden Early Arthritis Clinic (Leiden-EAC), BARFOT, Lund, Iceland, NDB and Wichita). In total 9412 radiographs were assessed. Multivariate normal regression and linear regression analyses were performed. Data were summarised in a random effects inverse variance meta-analysis. Results When comparing radiological progression for RA patients that were never, past and current smokers, smoking was significantly associated with more severe joint damage in Leiden-EAC (p=0.042) and BARFOT (p=0.015) RA patients. No significant associations were found in the other cohorts, though a meta-analysis on the six cohorts showed significantly more severe joint damage progression in smokers (p=0.01). Since smoking predisposes to ACPA, analyses were repeated with ACPA as additional adjustment factor. Then the association was lost (meta-analysis p=0.29). Conclusions This multi-cohort study indicated that the effect of smoking on joint damage is mediated via ACPA and that smoking is not an independent risk factor for radiological progression in RA.

Studying associations between variants in TRAF1-C5 and TNFAIP3-OLIG3 and the progression of joint destruction in rheumatoid arthritis in multiple cohorts

The severity of joint destruction in rheumatoid arthritis (RA) is highly variable between patients. Recent twin and population studies indicated that the severity of joint destruction is influenced by genetic factors.1 ,2 Previously, we reported the association of rs10818488 ( TRAF1-C5 ) and rs675520 ( TNFAIP3-OLIG3 ) with progression of joint destruction.3 ,4 The genes near these loci encode for tumour necrosis factor receptor-associated factor-1 ( TRAF1 ), complement component-5 ( C5 ) and tumour necrosis factor α-induced protein-3 ( TNFAIP3 ; a protein that inhibits NF-κ B activation). A basic principle in genetic association studies is to evaluate multiple cohorts to validate observed findings. We therefore studied both single-nucleotide polymorphisms in several RA cohorts with radiological follow-up data. Six thousand two hundred and eighty-two x-rays of 2666 RA patients were studied: 147 patients from Lund (Sweden), 385 patients from Sheffield (UK), 285 patients from Iceland, 384 patients from the North American Rheumatoid Arthritis Consortium (NARAC), 756 patients from the National Databank of Rheumatic Diseases (NDB), 113 patients from Wichita and 596 patients from the Leiden Early Arthritis Clinic (Leiden-EAC) cohort (table 1). Detailed information on these datasets is provided elsewhere.2 ,5,–,10 …

A genetic variant in granzyme B is associated with progression of joint destruction in rheumatoid arthritis

OBJECTIVE Genetic factors account for an estimated 45-58% of the variance in joint destruction in rheumatoid arthritis (RA). The serine proteinase granzyme B induces target cell apoptosis, and several in vitro studies suggest that granzyme B is involved in apoptosis of chondrocytes. Serum levels of granzyme B are increased in RA and are also associated with radiographic erosions. The aim of this study was to investigate GZMB as a candidate gene accounting for the severity of joint destruction in RA. METHODS A total of 1,418 patients with 4,885 radiograph sets of the hands and feet from 4 independent cohorts were studied. First, explorative analyses were performed in 600 RA patients in the Leiden Early Arthritis Clinic cohort. Fifteen single-nucleotide polymorphisms (SNPs) tagging GZMB were tested. Significantly associated SNPs were genotyped in data sets representing patients from the Groningen, Sheffield, and Lund cohorts. In each data set, the relative increase in the annual rate of progression in the presence of a genotype was assessed. Data were summarized in a meta-analysis. The association of GZMB with the RNA expression level of the GZMB genomic region was tested by mapping expression quantitative trait loci (QTLs) on 1,469 whole blood samples. RESULTS SNP rs8192916 was significantly associated with the rate of joint destruction in the first cohort and in the meta-analysis of all data sets. Patients homozygous for the minor allele of rs8192916 had a higher rate of joint destruction per year compared with other patients (P = 7.8 × 10(-4)). Expression QTL of GZMB identified higher expression in the presence of the minor allele of rs8192916 (P = 2.27 × 10(-5)). CONCLUSION SNP rs8192916 located in GZMB is associated with the progression of joint destruction in RA as well as with RNA expression in whole blood.

Evaluating joint destruction in rheumatoid arthritis: is it necessary to radiograph both hands and feet?

Background Radiological damage is an important outcome measure in rheumatoid arthritis (RA), both for research and clinical purposes. Depending on the setting, both hands and feet are radiographed, or only a part of these. It is unknown whether radiographing part of the four extremities gives comparable information to radiographing both hands and feet. This study therefore aimed to compare the radiological information obtained both when evaluating single time point radiographs and progression over time, in early and advanced RA. Methods 6261 sets of hands and feet x-rays of 2193 RA patients from Leiden, Groningen (both from The Netherlands) and North America were studied. Correlations between joint damage at different regions were compared (unilateral vs bilateral and hands vs feet). Analyses were done at single time points (cross-sectional) and for progression over time (longitudinal), both for continuous severity measures (Sharp/van der Heijde score; SHS) and binomial measures of erosiveness. Results When studying single time points, the severity of joint damage (SHS) is highly correlated between left and right, but weakly correlated between hands and feet. Correlation coefficients were higher in advanced than early RA. These findings were comparable in the three datasets. When evaluating erosiveness using only unilateral x-rays or hands without feet, 19.3% and 24.0–40.4% are incorrectly classified as non-erosiveness. Similarly, when evaluating disease progression by imaging only unilateral x-rays or only hand x-rays, progression would have been missed in 11.6–16.2% and 21.2–31.0% of patients. Conclusion Performing x-rays of both hands and feet yields additive information compared with imaging only a part of these.

Association of Genetic Variants in the IL4 and IL4R Genes With the Severity of Joint Damage in Rheumatoid Arthritis: A Study in Seven Cohorts

OBJECTIVE The progression of joint destruction in rheumatoid arthritis (RA) is determined by genetic factors. Changes in IL4 and IL4R genes have been associated with RA severity, but this finding has not been replicated. This study was undertaken to investigate the association between IL4- and IL4R-tagging single-nucleotide polymorphisms (SNPs) and the progression rate of joint damage in RA in a multicohort candidate gene study. METHODS IL4- and IL4R-tagging SNPs (n = 8 and 39, respectively) were genotyped in 600 RA patients for whom 2,846 sets of radiographs of the hands and feet were obtained during 7 years of followup. Subsequently, SNPs significantly associated with the progression of joint damage were genotyped and studied in relation to 3,415 radiographs of 1,953 RA patients; these included data sets from Groningen (The Netherlands), Lund (Sweden), Sheffield (UK), the North American Rheumatoid Arthritis Consortium (US), Wichita (US), and the National Data Bank (US). The relative increase in progression rate per year in the presence of a genotype was determined in each cohort. An inverse variance weighting meta-analysis was performed on the 6 data sets that together formed the replication phase. RESULTS In the discovery phase, none of the IL4 SNPs and 7 of the IL4R SNPs were significantly associated with the joint damage progression rate. In the replication phase, 2 SNPs in the IL4R gene were significantly associated with the joint damage progression rate (rs1805011 [P = 0.02] and rs1119132 [P = 0.001]). CONCLUSION Genetic variants in IL4R were identified, and their association with the progression rate of joint damage in RA was independently replicated.

Does the season at symptom onset influence the long-term severity of radiographic joint destruction in rheumatoid arthritis?

Season-associated environmental factors have been related to the onset of rheumatoid arthritis (RA) and the severity of joint complaints.1 ,2 A recent study demonstrated that the onset of arthritis symptoms during winter or spring was associated with more radiographic joint damage after 1 year.3 This led us to evaluate the influence of the season of symptom onset on long-term radiographic progression. Six hundred and eighty-eight RA-patients, from the Leiden Early Arthritis Clinic (EAC) and 830 RA-patients from the Swedish BARFOT-study were included in the study.4 ,5 These cohorts were similar in the percentage of women patients, age, symptom duration, swollen joint count, C reactive protein and the percentage of anti-cyclic citrullinated protein antibody positive patients (data not shown). During a follow-up period of 5 and 7 years, a total of 6990 hands and feet x-ray sets were obtained and scored for joint damage according to the Sharp-van-der-Heijde method ( all …

THU0001 Variation in granzyme-b is associated with progression of joint destruction in rheumatoid arthritis

Background The severity of joint destruction in Rheumatoid Arthritis (RA) is highly variable between patients and 45-58% of the variance is estimated to be explained by genetic factors. The serine proteinase Granzyme-B (GZMB) is important for the rapid induction of target cell apoptosis by cytotoxic T-cells and several in vitro studies suggested that GZMB is involved in apoptosis of chondrocytes. GZMB serum levels are increased in RA and the height of these levels are associated with higher risk of radiographic erosions. Objectives To investigate GZMB as a candidate gene for the severity of the rate of joint destruction in RA. Methods 1,418 patients with 4,885 X-ray sets of both hands and feet of four independent datasets were studied. First, explorative analyses were performed on 600 RA-patients enrolled in the Leiden-Early-Arthritis-Clinic. 16 SNPs tagged GZMB and were tested. Significantly associated SNPs were genotyped in datasets from Groningen (NL), Sheffield (UK) and Lund (Sw). In each dataset the relative increase of the progression rate per year in the presence of a genotype was assessed. Subsequently, data were summarized in a meta-analysis. To assess the functional potential of GZMB, the association of the identified SNPs with RNA-expression level of the genomic region of GZMB was tested, by mapping expression quantitative trait locus (eQTL) on 1,469 whole blood samples. Results In the discovery cohort, patients homozygous for the minor allele of rs8192916 had a 1.05 (95%CI 1.02-1.08) fold rate of joint destruction per year compared to other patients (P=1.2×10-3). Thisassociation remained significant in the meta-analysis on all datasets (P=7.8×10-4). eQTL of GZMB tested a higher expression in the presence of the minor allele of rs8192916 (P=2.2×10-5). Conclusions Rs8192916 located in GZMB is associated with the progression of joint destruction in RA as well as with RNA expression levels in whole blood. Future studies are needed to evaluate whether rs8291916, or a genetic variant linked to this SNP, is associated with an enhanced destructive process or with propagation of the immune response, to further explain the observations done on DNA and RNA levels in RA. Disclosure of Interest None Declared

Brief Report: Association of Genetic Variants in theIL4andIL4RGenes With the Severity of Joint Damage in Rheumatoid Arthritis: A Study in Seven Cohorts: Association ofIL4RSNPs With Joint Damage in RA

OBJECTIVE The progression of joint destruction in rheumatoid arthritis (RA) is determined by genetic factors. Changes in IL4 and IL4R genes have been associated with RA severity, but this finding has not been replicated. This study was undertaken to investigate the association between IL4- and IL4R-tagging single-nucleotide polymorphisms (SNPs) and the progression rate of joint damage in RA in a multicohort candidate gene study. METHODS IL4- and IL4R-tagging SNPs (n = 8 and 39, respectively) were genotyped in 600 RA patients for whom 2,846 sets of radiographs of the hands and feet were obtained during 7 years of followup. Subsequently, SNPs significantly associated with the progression of joint damage were genotyped and studied in relation to 3,415 radiographs of 1,953 RA patients; these included data sets from Groningen (The Netherlands), Lund (Sweden), Sheffield (UK), the North American Rheumatoid Arthritis Consortium (US), Wichita (US), and the National Data Bank (US). The relative increase in progression rate per year in the presence of a genotype was determined in each cohort. An inverse variance weighting meta-analysis was performed on the 6 data sets that together formed the replication phase. RESULTS In the discovery phase, none of the IL4 SNPs and 7 of the IL4R SNPs were significantly associated with the joint damage progression rate. In the replication phase, 2 SNPs in the IL4R gene were significantly associated with the joint damage progression rate (rs1805011 [P = 0.02] and rs1119132 [P = 0.001]). CONCLUSION Genetic variants in IL4R were identified, and their association with the progression rate of joint damage in RA was independently replicated.