Elisabeth Brouwer

Genome-wide association study meta-analysis identifies seven new rheumatoid arthritis risk loci

To identify new genetic risk factors for rheumatoid arthritis, we conducted a genome-wide association study meta-analysis of 5,539 autoantibody-positive individuals with rheumatoid arthritis (cases) and 20,169 controls of European descent, followed by replication in an independent set of 6,768 rheumatoid arthritis cases and 8,806 controls. Of 34 SNPs selected for replication, 7 new rheumatoid arthritis risk alleles were identified at genome-wide significance (P < 5 × 10−8) in an analysis of all 41,282 samples. The associated SNPs are near genes of known immune function, including IL6ST, SPRED2, RBPJ, CCR6, IRF5 and PXK. We also refined associations at two established rheumatoid arthritis risk loci (IL2RA and CCL21) and confirmed the association at AFF3. These new associations bring the total number of confirmed rheumatoid arthritis risk loci to 31 among individuals of European ancestry. An additional 11 SNPs replicated at P < 0.05, many of which are validated autoimmune risk alleles, suggesting that most represent genuine rheumatoid arthritis risk alleles.

Effectiveness of Rituximab Treatment in Primary Sjogren's Syndrome A Randomized, Double-Blind, Placebo-Controlled Trial

OBJECTIVE To study the efficacy and safety of B cell depletion with rituximab, a chimeric murine/human anti-CD20 monoclonal antibody, in patients with primary Sjögrens syndrome (SS) in a double-blind, randomized, placebo-controlled trial. METHODS Patients with active primary SS, as determined by the revised American-European Consensus Group criteria, and a rate of stimulated whole saliva secretion of > or =0.15 ml/minute were treated with either rituximab (1,000 mg) or placebo infusions on days 1 and 15. Patients were assigned randomly to a treatment group in a ratio of 2:1 (rituximab:placebo). Followup was conducted at 5, 12, 24, 36, and 48 weeks. The primary end point was the stimulated whole saliva flow rate, while secondary end points included functional, laboratory, and subjective variables. RESULTS Thirty patients with primary SS (29 female) were randomly allocated to a treatment group. The mean +/- SD age of the patients receiving rituximab was 43 +/- 11 years and the disease duration was 63 +/- 50 months, while patients in the placebo group were age 43 +/- 17 years and had a disease duration of 67 +/- 63 months. In the rituximab group, significant improvements, in terms of the mean change from baseline compared with that in the placebo group, were found for the primary end point of the stimulated whole saliva flow rate (P = 0.038 versus placebo) and also for various laboratory parameters (B cell and rheumatoid factor [RF] levels), subjective parameters (Multidimensional Fatigue Inventory [MFI] scores and visual analog scale [VAS] scores for sicca symptoms), and extraglandular manifestations. Moreover, in comparison with baseline values, rituximab treatment significantly improved the stimulated whole saliva flow rate (P = 0.004) and several other variables (e.g., B cell and RF levels, unstimulated whole saliva flow rate, lacrimal gland function on the lissamine green test, MFI scores, Short Form 36 health survey scores, and VAS scores for sicca symptoms). One patient in the rituximab group developed mild serum sickness-like disease. CONCLUSION These results indicate that rituximab is an effective and safe treatment strategy for patients with primary SS.

T cell reactivity to proteinase 3 and myeloperoxidase in patients with Wegener's granulomatosis (WG).

T cell‐mediated immunity is hypothesized to play an important role in the pathogenesis of granulomatous inflammation and vasculitis as found in patients with WG. The antigenic specificities of those T cells remain, however, unknown. Anti‐neutrophil cytoplasmic antibodies (ANCA) present in patients with WG are directed to proteinase 3 (PR3) and myeloperoxidase (MPO). In the present study we investigated the proliferative capacity of peripheral Wood mononuclear cells (PBMC) from patients with WG and age‐and sex‐matched controls in response to the WG autoantigens PR3 and MPO. Possible mitogenic effects of active PR3 and toxic effects of active MPO were excluded by using heat‐inactivated PR3 and MPO. Antigen‐specific stimulation induced by these autoantigens was studied by using processed PR3 and MPO in the lymphocyte stimulation test (LST). Proliferation induced by processed antigen correlated with that by heat‐inactivated free antigen. The general capacity to proliferate in response to mitogens and recall antigens did not differ between patients and controls. However, patients with WG who were or had been positive for PR3‐ANCA (n = 17) responded more strongly to PR3 than to MPO and showed higher responses to PR3 compared with controls (n = 13). Within the PR3‐ANCA group T cell proliferation did not correlate with ANCA titre. In a small group of patients with MPO‐ANCA (n=5) no differences were observed compared with controls for MPO‐specific proliferation. The data presented demonstrate that autoreactive PR3‐specific T cells are present in patients with WG. Their fine specificity and possible role in the pathogenesis of WG have to be defined in further studies.

Periodontitis in established rheumatoid arthritis patients: a cross-sectional clinical, microbiological and serological study

IntroductionThe association between rheumatoid arthritis (RA) and periodontitis is suggested to be linked to the periodontal pathogen Porphyromonas gingivalis. Colonization of P. gingivalis in the oral cavity of RA patients has been scarcely considered. To further explore whether the association between periodontitis and RA is dependent on P. gingivalis, we compared host immune responses in RA patients with and without periodontitis in relation to presence of cultivable P. gingivalis in subgingival plaque.MethodsIn 95 RA patients, the periodontal condition was examined using the Dutch Periodontal Screening Index for treatment needs. Subgingival plaque samples were tested for presence of P. gingivalis by anaerobic culture technique. IgA, IgG and IgM antibody titers to P. gingivalis were measured by ELISA. Serum and subgingival plaque measures were compared to a matched control group of non-RA subjects.ResultsA higher prevalence of severe periodontitis was observed in RA patients in comparison to matched non-RA controls (27% versus 12%, p < 0.001). RA patients with severe periodontitis had higher DAS28 scores than RA patients with no or moderate periodontitis (p < 0.001), while no differences were seen in IgM-RF or ACPA reactivity. Furthermore, RA patients with severe periodontitis had higher IgG- and IgM-anti P. gingivalis titers than non-RA controls with severe periodontitis (p < 0.01 resp. p < 0.05), although subgingival occurrence of P. gingivalis was not different.ConclusionsSeverity of periodontitis is related to severity of RA. RA patients with severe periodontitis have a more robust antibody response against P. gingivalis than non-RA controls, but not all RA patients have cultivable P. gingivalis.

Baseline predictors of response and discontinuation of tumor necrosis factor-alpha blocking therapy in ankylosing spondylitis: a prospective longitudinal observational cohort study

IntroductionIdentifying ankylosing spondylitis (AS) patients who are likely to benefit from tumor necrosis factor-alpha (TNF-α) blocking therapy is important, especially in view of the costs and potential side effects of these agents. Recently, the AS Disease Activity Score (ASDAS) has been developed to assess both subjective and objective aspects of AS disease activity. However, data about the predictive value of the ASDAS with respect to clinical response to TNF-α blocking therapy are lacking. The aim of the present study was to identify baseline predictors of response and discontinuation of TNF-α blocking therapy in AS patients in daily clinical practice.MethodsAS outpatients who started TNF-α blocking therapy were included in the Groningen Leeuwarden Ankylosing Spondylitis (GLAS) study, an ongoing prospective longitudinal observational cohort study with follow-up visits according to a fixed protocol. For the present analysis, patients were excluded if they had previously received anti-TNF-α treatment. Predictor analyses of response and treatment discontinuation were performed using logistic and Cox regression models, respectively.ResultsBetween November 2004 and April 2010, 220 patients started treatment with infliximab (n = 32), etanercept (n = 137), or adalimumab (n = 51). At three and six months, 68% and 63% of patients were Assessments in Ankylosing Spondylitis (ASAS)20 responders, 49% and 46% ASAS40 responders, and 49% and 50% Bath Ankylosing Spondylitis Disease Activity Index (BASDAI)50 responders, respectively. Baseline predictors of response were younger age, male gender, higher ASDAS score, higher erythrocyte sedimentation rate (ESR) level, higher C-reactive protein (CRP) level, presence of peripheral arthritis, higher patients global assessment of disease activity, and lower modified Schober test. In August 2010, 64% of patients were still using their TNF-α blocking agent with a median follow-up of 33.1 months (range 2.4 to 68.2). Baseline predictors of discontinuation of TNF-α blocking therapy were female gender, absence of peripheral arthritis, higher BASDAI, lower ESR level, and lower CRP level.ConclusionsBesides younger age and male gender, objective variables such as higher inflammatory markers or ASDAS score were identified as independent baseline predictors of response and/or continuation of TNF-α blocking therapy. In contrast, higher baseline BASDAI score was independently associated with treatment discontinuation. Based on these results, it seems clinically relevant to include more objective variables in the evaluation of anti-TNF-α treatment.

Trial of Tocilizumab in Giant-Cell Arteritis

Background Giant‐cell arteritis commonly relapses when glucocorticoids are tapered, and the prolonged use of glucocorticoids is associated with side effects. The effect of the interleukin‐6 receptor alpha inhibitor tocilizumab on the rates of relapse during glucocorticoid tapering was studied in patients with giant‐cell arteritis. Methods In this 1‐year trial, we randomly assigned 251 patients, in a 2:1:1:1 ratio, to receive subcutaneous tocilizumab (at a dose of 162 mg) weekly or every other week, combined with a 26‐week prednisone taper, or placebo combined with a prednisone taper over a period of either 26 weeks or 52 weeks. The primary outcome was the rate of sustained glucocorticoid‐free remission at week 52 in each tocilizumab group as compared with the rate in the placebo group that underwent the 26‐week prednisone taper. The key secondary outcome was the rate of remission in each tocilizumab group as compared with the placebo group that underwent the 52‐week prednisone taper. Dosing of prednisone and safety were also assessed. Results Sustained remission at week 52 occurred in 56% of the patients treated with tocilizumab weekly and in 53% of those treated with tocilizumab every other week, as compared with 14% of those in the placebo group that underwent the 26‐week prednisone taper and 18% of those in the placebo group that underwent the 52‐week prednisone taper (P<0.001 for the comparisons of either active treatment with placebo). The cumulative median prednisone dose over the 52‐week period was 1862 mg in each tocilizumab group, as compared with 3296 mg in the placebo group that underwent the 26‐week taper (P<0.001 for both comparisons) and 3818 mg in the placebo group that underwent the 52‐week taper (P<0.001 for both comparisons). Serious adverse events occurred in 15% of the patients in the group that received tocilizumab weekly, 14% of those in the group that received tocilizumab every other week, 22% of those in the placebo group that underwent the 26‐week taper, and 25% of those in the placebo group that underwent the 52‐week taper. Anterior ischemic optic neuropathy developed in one patient in the group that received tocilizumab every other week. Conclusions Tocilizumab, received weekly or every other week, combined with a 26‐week prednisone taper was superior to either 26‐week or 52‐week prednisone tapering plus placebo with regard to sustained glucocorticoid‐free remission in patients with giant‐cell arteritis. Longer follow‐up is necessary to determine the durability of remission and safety of tocilizumab. (Funded by F. Hoffmann–La Roche; ClinicalTrials.gov number, NCT01791153.)

Common and different genetic background for rheumatoid arthritis and coeliac disease

Recent genome-wide association studies (GWAS) have revealed genetic risk factors in autoimmune and inflammatory disorders. Several of the associated genes and underlying pathways are shared by various autoimmune diseases. Rheumatoid arthritis (RA) and coeliac disease (CD) are two autoimmune disorders which have commonalities in their pathogenesis. We aimed to replicate known RA loci in a Dutch RA population, and to investigate whether the effect of known RA and CD risk factors generalize across the two diseases. We selected all loci associated to either RA or CD in a GWAS and confirmed in an independent cohort, with a combined P-value cut-off P < 5 x 10(-6). We genotyped 11 RA and 11 CD loci in 1368 RA patients, 795 CD patients and 1683 Dutch controls. We combined our results in a meta-analysis with UK GWAS on RA (1860 cases; 2938 controls) and CD (767 cases; 1422 controls). In the Dutch RA cohort, the PTPN22 and IL2/IL21 variants showed convincing association (P = 3.4 x 10(-12) and P = 2.8 x 10(-4), respectively). Association of RA with the known CD risk variant in the SH2B3 was also observed, predominantly in the subgroup of rheumatoid factor-positive RA patients (P = 0.0055). In a meta-analysis of Dutch and UK data sets, shared association with six loci (TNFAIP3, IL2/IL21, SH2B3, LPP, MMEL1/TNFRSF14 and PFKFB3/PRKCQ) was observed in both RA and CD cohorts. We confirmed two known loci and identified four novel ones for shared CD-RA genetic risk. Most of the shared loci further emphasize a role for adaptive and innate immunity in these diseases.

LRegulation of cytokine-induced HW-1 alpha expression in rheumatoid synovial fibroblasts

Abstract:  The transcription factor hypoxia‐inducible factor (HIF)‐1 plays a central physiological role in oxygen and energy homeostasis, and is activated during hypoxia by stabilization of the subunit HIF‐1α. Activation can also occur by proinflammatory cytokines during inflammation. Hypoxia, as well as proinflammatory cytokines, plays an important role in the synovia in rheumatoid arthritis (RA) patients. Expression of HIF‐1α has been demonstrated in RA synovial lining layer. The aim of the study was to investigate the regulation of the intracellular signal transduction pathways, involved in the expression of HIF‐1α, and in the expression of genes regulated by HIF‐1α in rheumatoid synovial fibroblasts (RSF). RSF were cultured under proinflammatory conditions (IL‐1β and TNF‐α stimulation) and under chemical hypoxia (CoCl2 treatment). Expression of HIF‐1α was analyzed in nuclear extracts by Western blotting. The effect of inhibitors of the PI3K and the ERK pathway on HIF‐1α protein expression was measured. mRNA expression of HIF‐1α, COX‐2, vascular endothelial growth factor (VEGF), and stromal cell‐derived factor (SDF)‐1 was determined by real‐time RT‐PCR, and protein production of VEGF and SDF‐1 by ELISA. Treatment of the synovial fibroblasts with 150 mM CoCl2 as well as stimulation with 10 ng/mL IL‐1β or TNF‐α resulted in strong protein expression of HIF‐1α, measured with Western blotting. Pretreatment with the MEK1/2 inhibitor PD98059 as well as the PI3K inhibitor LY294002 resulted in inhibition of the cytokine‐induced HIF‐1α expression. Furthermore, it was shown that cytokine‐induced mRNA expression of HIF‐1α was inhibited by the PI3K inhibitor. We found that cytokine stimulation induced VEGF mRNA and protein production, but no significant effect of kinase inhibition was found on VEGF production in cytokine‐stimulated RSF. Both the ERK pathway and the PI3K pathway are involved in the cytokine‐induced HIF‐1α expression in RSF and in the expression of proangiogenic factors.

The periodontium of periodontitis patients contains citrullinated proteins which may play a role in ACPA (anti-citrullinated protein antibody) formation

AIM To determine the presence and location (stroma versus epithelium) of citrullinated proteins in periodontitis tissue as compared to non-periodontitis tissue and synovial tissue of RA patients. MATERIALS & METHODS Periodontitis, healthy periodontal and RA-affected synovial tissue samples were collected in addition to buccal swabs. These samples were stained for the presence of citrullinated proteins using polyclonal (Ab5612) and monoclonal (F95) antibodies. Furthermore, Western blotting with F95 was performed on lysates prepared from periodontal and synovial tissues. RESULTS In periodontitis stroma, increased citrullinated protein presence (80%) was observed compared with control stroma (33%), the latter was associated with inflammation of non-periodontitis origin. Periodontal epithelium always stained positive for Ab5612. Noteworthy, only periodontitis-affected epithelium stained positive for F95. All buccal mucosal swabs and 3 of 4 synovial tissue samples stained positive for both Ab5612 and F95. Western blotting with F95 showed presence of similar citrullinated proteins in both periodontitis and RA-affected synovial tissue. CONCLUSION Within the periodontal stroma, citrullination is an inflammation-depended process. In periodontal epithelium, citrullination is a physiological process. Additional citrullinated proteins are formed in periodontitis, apparently similar to those formed in RA-affected synovial tissue. Periodontitis induced citrullination may play a role in the aetiology of rheumatoid arthritis.

Immuno-miRs: critical regulators of T-cell development, function and ageing

MicroRNAs (miRNAs) are instrumental to many aspects of immunity, including various levels of T‐cell immunity. Over the last decade, crucial immune functions were shown to be regulated by specific miRNAs. These ‘immuno‐miRs’ regulate generic cell biological processes in T cells, such as proliferation and apoptosis, as well as a number of T‐cell‐specific features that are fundamental to the development, differentiation and function of T cells. In this review, we give an overview of the current literature with respect to the role of miRNAs at various stages of T‐cell development, maturation, differentiation, activation and ageing. Little is known about the involvement of miRNAs in thymic T‐cell development, although miR‐181a and miR‐150 have been implicated herein. In contrast, several broadly expressed miRNAs including miR‐21, miR‐155 and miR‐17~92, have now been shown to regulate T‐cell activation. Other miRNAs, including miR‐146a, show a more T‐cell‐subset‐specific expression pattern and are involved in the regulation of processes unique to that specific T‐cell subset. Importantly, differences in the miRNA target gene repertoires of different T‐cell subsets allow similar miRNAs to control different T‐cell‐subset‐specific functions. Interestingly, several of the here described immuno‐miRs have also been implicated in T‐cell ageing and there are clear indications for causal involvement of miRNAs in immunosenescence. It is concluded that immuno‐miRs have a dynamic regulatory role in many aspects of T‐cell differentiation, activation, function and ageing. An important notion when studying miRNAs in relation to T‐cell biology is that specific immuno‐miRs may have quite unrelated functions in closely related T‐cell subsets.