A genome-wide association study of rheumatoid arthritis without antibodies against citrullinated peptides.

INTRODUCTION: Rheumatoid arthritis (RA) patients can be classified based on presence or absence of anticitrullinated peptide antibodies (ACPA) in their serum. This heterogeneity among patients may reflect important biological differences underlying the disease process. To date, the majority of genetic studies have focused on the ACPA-positive group. Therefore, our goal was to analyse the genetic risk factors that contribute to ACPA-negative RA. METHODS: We performed a large-scale genome-wide association study (GWAS) in three Caucasian European cohorts comprising 1148 ACPA-negative RA patients and 6008 controls. All patients were screened using the Illumina Human Cyto-12 chip, and controls were genotyped using different genome-wide platforms. Population-independent analyses were carried out by means of logistic regression. Meta-analysis with previously published data was performed as follow-up for selected signals (reaching a total of 1922 ACPA-negative RA patients and 7087 controls). Imputation of classical HLA alleles, amino acid residues and single nucleotide polymorphisms was undertaken. RESULTS: The combined analysis of the studied cohorts resulted in identification of a peak of association in the HLA-region and several suggestive non-HLA associations. Meta-analysis with previous reports confirmed the association of the HLA region with this subset and an observed association in the CLYBL locus remained suggestive. The imputation and deep interrogation of the HLA region led to identification of a two amino acid model (HLA-B at position 9 and HLA-DRB1 at position 11) that accounted for the observed genome-wide associations in this region. CONCLUSIONS: Our study shed light on the influence of the HLA region in ACPA-negative RA and identified a suggestive risk locus for this condition.

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.

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.

Hypoxia inducible factor-1-alpha (HIF-1alpha) is related to both angiogenesis and inflammation in rheumatoid arthritis.

OBJECTIVES: Despite the important role of the transcription factor HIF-1alpha in angiogenesis and inflammation, only a few studies on HIF-1alpha expression have been performed in RA patients. The aim of the present study was to identify the layer in synovial tissue of RA patients where HIF1a is expressed and to find out whether HIF-1alpha expression is related to both angiogenesis and inflammation in synovium from RA patients. METHODS: A reproducible staining method for HIF-1alpha was developed. HIF-1alpha -positive cells were quantified in synovial tissue from patients with RA. As control we used synovial tissue from patients with osteoarthritis (OA). The number of HIF-1alpha-positive cells was compared with the number of blood vessels present and was correlated with the amount of inflammation. The amount of inflammation was determined by counting inflammatory cells, by estimating the proliferation marker Ki67 in inflamed tissue, and by using a recently published synovitis score which gives an accurate estimate of the amount of inflammation present. RESULTS: HIF-1alpha was expressed weakly in the lining layer and strongly in the sublining layer in RA synovial tissue. In contrast, HIF-1alpha was only weakly expressed in OA synovial tissue. The number of HIF-1alpha -positive cells correlated strongly with the number of blood vessels in RA synovial tissue and with inflammatory endothelial cell infiltration (blood vessels), cell proliferation (Ki67) and the synovitis score. CONCLUSIONS: HIF-1alpha expression is strongest in the sub-lining layer of RA synovium and is related to both angiogenesis and inflammation in synovium from RA patients. These results thus suggest that HIF-1alpha could serve as an important new therapeutic target in RA, targeting both angiogenesis and inflammation.

Increased incidence of azathioprine-induced pancreatitis in Crohn's disease compared with other diseases.

BACKGROUND: Azathioprine is widely used in Crohn's disease. A major drawback is the occurrence of side-effects, especially acute pancreatitis. Acute pancreatitis is rarely seen when azathioprine is used for other diseases than Crohn's disease. AIM: To survey side-effects of azathioprine after liver or renal transplantation, for systemic lupus erythematosis, Wegener's granulomatosis, autoimmune hepatitis, rheumatoid arthritis, ulcerative colitis or Crohn's disease. METHODS: A computerized search using the term 'azathioprine' or 'imuran' was performed on the Hospital Information System of the university hospital Groningen, resulting in 1564 patients matching our criteria. RESULTS: Eleven of 224 patients with Crohn's disease experienced acute pancreatitis (4.9%) compared with two of 129 (1.5%) with autoimmune hepatitis, two of 388 (0.5%) after renal transplantation, one of 254 (0.4%) after liver transplantation. Acute pancreatitis was more prevalent in Crohn's disease compared with any other disease. Azathioprine-toxicity necessitating withdrawal occurred significantly (P < 0,05) more in rheumatoid arthritis (78 of 317), ulcerative colitis (20 of 94) and Crohn's disease (52 of 224) compared with systemic lupus erythematosis (five of 73), Wegener's granulomatosis (six of 85), autoimmune hepatitis (eight of 129), after liver transplantation (17 of 254) and after renal transplantation (22 of 388). CONCLUSIONS: Acute pancreatitis is strongly associated with Crohn's disease and rarely occurs with other underlying conditions. Overall azathioprine-induced toxicity and the necessity of withdrawal is more common in inflammatory bowel disease and rheumatoid arthritis compared with other diseases.

Serum matrix metalloproteinase 3 levels in comparison to C-reactive protein in periods with and without progression of radiological damage in patients with early rheumatoid arthritis.

OBJECTIVE: To evaluate serum matrix metalloproteinase 3 (MMP-3) levels in comparison to C-reactive protein (CRP) in periods with and without progression of radiological damage in patients with early rheumatoid arthritis (RA). METHODS: Thirty-two patients with RA and radiological progression (> or = 5 points according to the Sharp/van der Heijde method) during 6 months followed by a 6-month period without radiological progression (< or = 1 point) were selected from a prospective follow-up study of early RA patients. Serum MMP-3 levels, CRP, the erythrocyte sedimentation rate (ESR), disease activity index (DAS), swollen joint count (SJC), tender joint count (TJC), and Ritchie articular index (RAI) were measured monthly and results were transformed into mean values for the 6-month periods. RESULTS: During the period with radiological progression the mean serum MMP-3 correlated significantly with the mean CRP (r = 0.68, p < 0.001), ESR (r = 0.54, p = 0.001) and swollen joint count (r = 0.48, p = 0.006). In the period without radiological progression the mean serum MMP-3 only correlated with the mean CRP (r = 0.44, p = 0.012). Individual changes--expressed in percentages (%)--between the two periods showed a decrease in both the mean serum MMP-3 and CRP in 19 and an increase in 3 patients, in parallel with other markers of disease activity in these patients (69% of cases). The individual change (%) in mean serum MMP-3 or CRP did not correlate with the difference in radiological progression between the two periods. CONCLUSIONS: Serum MMP-3 and CRP are closely related and there seems to be no difference between serum MMP-3 and CRP with regard to the monitoring of the progression of radiological damage.

Serum matrix metalloproteinase 3 in early rheumatoid arthritis is correlated with disease activity and radiological progression.

OBJECTIVE: To analyze the clinical significance of serial measurements of serum matrix metalloproteinase 3 (MMP-3) levels in relation to markers of disease activity and radiological progression in early rheumatoid arthritis (RA). METHODS: In a 3 year prospective study of 33 patients with early RA (symptoms < 1 year at entry) monthly measurements of serum MMP-3 were transformed into time integrated values for 6 month periods for comparison with other markers of disease activity like swollen joint count (SJC), tender joint count (TJC), Ritchie articular index (RAI), the disease activity score (DAS), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and radiological progression, scored according to Sharp's method, in which erosions and joint space narrowing are scored separately and combined to a total Sharp score. RESULTS: Significant correlations were found between serum MMP-3 and SJC, ESR, and CRP during all periods and between 6 and 30 months with the DAS. There were no correlations between serum MMP-3 and TJC or the RAI. During the first 12 months serum MMP-3 was correlated only with the item joint space narrowing of the Sharp score. After 12 months of followup it was also correlated with the total Sharp score and after 18 months it was correlated with all 3 items of the Sharp score. There was a wide interindividual variation in the relation between serum MMP-3 and radiological progression but intraindividually this relation seemed to be rather constant. CONCLUSION: Time integrated values of serum MMP-3 are correlated with time integrated values of other markers of disease activity such as joint swelling, ESR, CRP, and the DAS. Of the radiological scores, as outcome measures, especially joint space narrowing correlated closely with cumulative serum MMP-3.

Serum levels of matrix metalloproteinase-3 in relation to the development of radiological damage in patients with early rheumatoid arthritis.

OBJECTIVE: To evaluate the significance of serum matrix metalloproteinase-3 (MMP-3) levels in relation to the development of radiological damage (X-ray damage) in early rheumatoid arthritis (RA). METHODS: Serum MMP-3 levels were measured in 46 healthy controls (CTRL), 19 osteoarthritis (OA) and 78 RA patients with joint symptoms for <1 yr at presentation (T0): 48 patients without and 30 with X-ray damage at T0. Serum MMP-3, measured by ELISA, and X-ray damage, scored according to Sharp's method, were assessed at 0, 6, 12 and 24 months. RESULTS: MMP-3 levels in CTRL and OA were low or undetectable with no differences between the groups (P=0.19). Levels in RA were higher than in CTRL (P<0.01). Initial MMP-3 levels in patients with X-ray damage at T0 (n=30) were higher than the levels in patients without any X-ray damage during follow-up (n=19) (P<0.01), but were not different from those in patients who developed X-ray damage during the study (n=29) (P=0.11). In the patients without X-ray damage at T0, there was a significant correlation between MMP-3 at T0 and the total X-ray damage after 6 months (r=0.34, P=0.02) and 12 months (r=0.32, P=0.03). This correlation was almost exclusively determined by joint space narrowing in the Sharp score. CONCLUSION: The serum MMP-3 level seems to be an indicator for the development of radiological damage in patients with early RA and appears to be particularly indicative of cartilage degradation.

Cytochrome b5 reductase deficiency, an uncommon cause of cyanosis.

A patient with cyanosis due to methaemoglobinaemia caused by cytochrome b5 reductase deficiency is described. Investigation of his family confirmed transmission of this disorder as an autosomal recessive trait. The consequences of this rare condition are discussed.