Characterization and use of the ECV304 autoantigenic citrullinome to understand anti-citrullinated protein/peptide autoantibodies in rheumatoid arthritis.

BACKGROUND: Anti-citrullinated protein antibodies (ACPAs) are highly specific for rheumatoid arthritis (RA). In vivo, ACPAs target peptidyl-citrulline epitopes (cit-) in a variety of proteins (cit-prot-ACPAs) and derived peptides (cit-pept-ACPAs) generated via the peptidylarginine deiminase (PAD) isoenzymes. We aimed to identify a cell line with self-citrullination capacity, to describe its autoantigenic citrullinome, and to test it as a source of autocitrullinated proteins and peptides. METHODS: Human cell lines were screened for cit-proteins by Western blot. PAD isoenzymes were identified by RT-PCR. Autocitrullination of ECV304 was optimized, and the ECV304 autocitrullinomes immunoprecipitated by sera from three RA patients were characterized by mass spectrometry. Cit-pept-ACPAs were detected using anti-CCP2 ELISA and cit-prot-ACPAs, by an auto-cit-prot-ECV304 ELISA. Sera from 177 RA patients, 59 non-RA rheumatic disease patients and 25 non-disease controls were tested. RESULTS: Of the seven cell lines studied, only ECV304 simultaneously overexpressed PAD2 and PAD3 and its extracts reproducibly autocitrullinated self and non-self-proteins. Proteomic analysis of the cit-ECV304 products immunoprecipitated by RA sera, identified novel cit-targets: calreticulin, profilin 1, vinculin, new 14-3-3 protein family members, chaperones, and mitochondrial enzymes. The auto-cit-prot-ECV304 ELISA had a sensitivity of 50% and a specificity of 95% for RA diagnosis. CONCLUSIONS: ECV304 cells overexpress two of the PAD isoenzymes capable of citrullinating self-proteins. These autocitrullinated cells constitute a basic and clinical research tool that enable the detection of cit-prot-ACPAs with high diagnostic specificity and allow the identification of the specific cit-proteins targeted by individual RA sera.

Assessing process of care in rheumatoid arthritis at McGill University hospitals.

OBJECTIVE: In rheumatoid arthritis (RA), quality indicators (QIs) are tools used to measure process of care. This study aimed to assess performance of selected QIs from the 2004 Arthritis Foundation's QI Set at 2 major sites of a university network of teaching hospitals. METHODS: The charts and electronic hospital records of 76 RA patients were audited to determine adherence to QIs. Logistic multivariate regression analyses were performed to investigate potential determinants of nonadherence and propose measures to facilitate better QI compliance, as a potential strategy towards RA care improvement. RESULTS: We identified consistent observance of QIs mandating prescription of disease-modifying antirheumatic drug therapy for all patients, drug adjustment with disease activity, prednisone tapering, and bisphosphonate therapy if indicated for patients on glucocorticoids. However, there was either lack of documentation or true inconsistent adherence to QIs dealing with radiograph performance, functional capacity assessment, and screening for hepatitis and tuberculosis before commencement of methotrexate and biologic agents, respectively. For the specific QIs analyzed, we did not find any definite independent associations with the studied variables. CONCLUSIONS: Our findings indicate that while there is frequent evidence for adherence to certain RA quality care standards at our centers, there is less compliance to others. Strategies to optimize the performance or documentation of those found most lacking, namely, functional capacity and screening for specific drug contraindications, could improve patient care. Radiographic disease monitoring, while lacking, may represent a move toward other more sensitive methods of RA progression detection, such as joint ultrasound. The inclusion of patient- and physician-derived information could help elucidate the reasons underlying nonadherence.

A retrospective review of rheumatology referral wait times within a health centre in Quebec, Canada.

It is important that inflammatory arthropathies such as rheumatoid arthritis be diagnosed promptly so that treatment can be administered in a timely fashion. However, there is considerable evidence that this process of care is delayed in many people. The aim of the study is to assess wait times between primary care referral and rheumatology assessment for new-onset inflammatory arthropathies. We performed a retrospective review related to new rheumatology consultations (N = 202) between September and November 2008 within the McGill University Health Centre, Montreal, Canada. At this centre, no formal triaging of rheumatology referrals exists. Of the 202 charts reviewed, wait times could be calculated in 164 cases. Only consultations for new-onset conditions were analyzed (N = 161). The results showed that patients with inflammatory arthritis were seen approximately 34.6 days (median 26) post-referral. Wait times for individuals who were ultimately diagnosed with non-urgent conditions (osteoarthritis, fibromyalgia and soft-tissue rheumatism) averaged 41.0 days (median 29). In conclusions, compared to non-urgent cases, individuals with inflammatory arthritis were seen about 1 week sooner. Nevertheless, provisional diagnosis provided on referrals did not appear to expedite wait times for persons with suspected inflammatory arthritis. This suggested that other factors, such as the concern of the patient, may have an influence on referral wait times. Implementation of a rapid access program or triage system may be helpful to further decrease wait times for inflammatory arthropathies.

The use of infliximab in academic rheumatology practice: an audit of early clinical experience.

OBJECTIVE: To audit a first clinical experience of treating rheumatic disease patients with infliximab in the setting of an academic tertiary care rheumatology practice. METHODS: The infusion history of patients referred to the McGill University Health Centre during the first 18 month period of a special access program for treatment with infliximab, a tumor necrosis factor-a antibody, was audited for disease characteristics, dosing schedule for infliximab, concomitant treatments, response rate, and side effect profile. RESULTS: Forty-one patients received a total of 300 infusions of infliximab over a period of 9 +/- 5 months (mean +/- standard deviation). Rheumatic disease indications were rheumatoid arthritis in 30, spondyloarthropathy in 6, psoriatic arthritis in 2, juvenile onset polyarthritis in 2, and scleroderma in one. Disease duration was 17 +/- 11 years. Concomitant treatment with steroids and methotrexate was present in 68% and 54%, respectively. Infliximab treatment was continued beyond 5 infusions or 22 weeks in 63%. Of the 26 patients continuing treatment, adjustment to dosing and/or interval schedule of infusions was made in 58%. The clinical response rate was moderately to greatly improved in 96%. Severe side effects considered directly related to the treatment were observed in 6 (15%) patients; less severe side effects, which did not preclude continuation of treatment but frequently required medical intervention, were noted in 93%. CONCLUSION: Infliximab is a valuable treatment for patients with resistant rheumatic diseases in the short term. Both the serious, and the frequent, more benign complication rate observed in this group of patients should alert physicians to be vigilant in the routine care of patients treated with infliximab.

Autoantigenic posttranslational modifications of proteins: does it apply to rheumatoid arthritis?

There are many posttranslational modifications of proteins of which all are homeostatically important either to carry out a particular structural or functional role or to allow efficient recycling of the amino acid constituents. An important feature of the modified proteins is the acquisition of autoantigenicity. That notion should have been recognized for years with the modifications of immunoglobulin G that constitute new targets for rheumatoid factors. Citrullination or the deimination of arginine residues in proteins creates epitopes that are targeted by rheumatoid autoantibodies with a diagnostic sensitivity and specificity of 40% to 70% and 92% to 99%, respectively. The how, when, and why of the responsible break in tolerance are largely speculative but apoptosis, multiple genetic and environmental influences are likely required. Identifying citrullinated proteins as autoantigens has resulted in new diagnostic and prognostic autoantibody markers for RA and studying the citrullination process and its nature and role in cell biology has provided new insights into its pathogenesis.