P Sidiras1,2, D Spruyt2, V Gangji3, V Imbault4, T Sokolova5, P Durez5, D Communi4, J Rasschaert2, V Badot6. 1. Department of Rheumatology, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium. 2. Laboratory of Bone and Metabolic Biochemistry, Université Libre de Bruxelles, Brussels, Belgium. 3. Department of Rheumatology, Tivoli University Hospital, La Louviere, Belgium. 4. IRIBHM, Université Libre de Bruxelles, Brussels, Belgium. 5. Department of Rheumatology, Saint-Luc University Hospital, Brussels, Belgium. 6. Department of Rheumatology, Brugmann University Hospital, Brussels, Belgium.
Abstract
Objectives: Anti-carbamylated protein antibodies (anti-CarP) are reported to be associated with increased disease activity and with more severe joint damage in rheumatoid arthritis (RA) patients. The present study investigated the presence of anti-CarP in various rheumatic diseases, and their specific clinical significance in RA, in Belgian rheumatology patients.Method: We tested sera from 254 RA patients, 56 healthy controls, and 153 patients with different rheumatic conditions: juvenile idiopathic arthritis (JIA), axial spondyloarthritis, systemic sclerosis, and Sjögren's syndrome (SS). An in-house enzyme-linked immunosorbent assay was used to detect immunoglobulin G antibodies against carbamylated foetal calf serum. Results: Anti-CarP were detected in 88 RA patients (34.6%), of whom 82% were also positive for anti-citrullinated protein antibodies (ACPAs) and 81% were also rheumatoid factor (RF) positive. Of note, 11 anti-CarP single-positive patients were detected (4.3%). The previously reported association with joint erosions was not detected. However, in ACPA- and RF-negative RA patients, the presence of anti-CarP was associated with higher disease activity and disability. Fifteen per cent of JIA patients and 30% of SS patients also tested positive for anti-CarP and their antibody levels did not differ significantly from those of anti-CarP-positive RA patients. Anti-CarP levels were, however, significantly higher in ACPA- or RF-positive patients. Conclusion: Anti-CarP antibodies were detected in the sera of a cohort of Belgian RA patients. Moreover, they were also detected in primary SS patients and in JIA patients. In the seronegative subset of RA patients, anti-CarP antibodies showed prognostic value.
Objectives: Anti-carbamylated protein antibodies (anti-CarP) are reported to be associated with increased disease activity and with more severe joint damage in rheumatoid arthritis (RA) patients. The present study investigated the presence of anti-CarP in various rheumatic diseases, and their specific clinical significance in RA, in Belgian rheumatology patients.Method: We tested sera from 254 RApatients, 56 healthy controls, and 153 patients with different rheumatic conditions: juvenile idiopathic arthritis (JIA), axial spondyloarthritis, systemic sclerosis, and Sjögren's syndrome (SS). An in-house enzyme-linked immunosorbent assay was used to detect immunoglobulin G antibodies against carbamylated foetal calf serum. Results: Anti-CarP were detected in 88 RApatients (34.6%), of whom 82% were also positive for anti-citrullinated protein antibodies (ACPAs) and 81% were also rheumatoid factor (RF) positive. Of note, 11 anti-CarP single-positive patients were detected (4.3%). The previously reported association with joint erosions was not detected. However, in ACPA- and RF-negative RApatients, the presence of anti-CarP was associated with higher disease activity and disability. Fifteen per cent of JIA patients and 30% of SS patients also tested positive for anti-CarP and their antibody levels did not differ significantly from those of anti-CarP-positive RApatients. Anti-CarP levels were, however, significantly higher in ACPA- or RF-positive patients. Conclusion: Anti-CarP antibodies were detected in the sera of a cohort of Belgian RApatients. Moreover, they were also detected in primary SS patients and in JIA patients. In the seronegative subset of RApatients, anti-CarP antibodies showed prognostic value.