Lan Do1, Gabriel Granåsen2, Urban Hellman1, Kristina Lejon3, Mats Geijer4,5,6, Xenofon Baraliakos7, Torsten Witte8, Helena Forsblad-d'Elia1,9,10. 1. Department of Public Health and Clinical Medicine, Rheumatology, Umeå University, Umeå, Sweden. 2. Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden. 3. Department of Clinical Microbiology, Infection and Immunology, Umeå University, Umeå, Sweden. 4. Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. 5. Department of Radiology, Region Västra Götaland, Sahlgrenska University Hospital, Gothenburg, Sweden. 6. Faculty of Medicine, Lund University, Lund, Sweden. 7. Department of Biochemistry, Ruhr-Universität Bochum, Bochum, Germany. 8. Department of Rheumatology and Clinical Immunology, Medical University Hannover, Hannover, Germany. 9. Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. 10. Department of Rheumatology, Region Västra Götaland, Sahlgrenska University Hospital, Gothenburg, Sweden.
Abstract
OBJECTIVES: Antibodies against anti-CD74 are related to axial spondyloarthritis (axSpA). The objectives were to study; 1) IgA anti-CD74 in radiographic (r)-axSpA patients in the Backbone cohort and to calculate the sensitivity and specificity of anti-CD74, 2) the fluctuation of IgA anti-CD74 levels in prospectively collected samples, 3) and to explore the relation between IgA anti-CD74 and radiographic spinal changes. METHODS: IgA anti-CD74 was analyzed by ELISA in 155 patients with r-axSpA and age- and sex-matched controls. BASDAI, ASDAS, BASFI, and BASMI were assessed and spinal radiographs were scored for r-axSpA related changes with mSASSS. Previously donated samples, before inclusion in the Backbone study, were identified in the Medical Biobank of Northern Sweden. RESULTS: A total of 155 patients comprising 69% men and 31% women, age (mean±SD) 55.5 ± 11.4 years, and 152 (98.1%) HLA-B27 positive, were included. The plasma level of IgA anti-CD74 was significantly higher in the patients, median (IQR), 12.9 (7.9-17.9) U/ml compared with controls 10.9 (7.2-14.6) U/ml, p= 0.003. IgA anti-CD74 was above the cut-off level of 20 U/ml in 36/155 (23.2%) patients and in 15/151 (9.9%) controls, p= 0.002. Multivariable logistic regression analyzes revealed that to have ≥1 syndesmophyte associated with IgA anti-CD74 (OR 5.64, 95% CI, 1.02-35.58, p= 0.048) adjusted for hsCRP, smoking, BMI, sex, and age. No distinct pattern of IgA anti-CD74 over time was revealed. CONCLUSION: Plasma levels of IgA anti-CD74 were increased in r-axSpA and independently associated with radiographic spinal changes which suggests that IgA anti-CD74 could play a role in the pathogenies of r-axSpA.
OBJECTIVES: Antibodies against anti-CD74 are related to axial spondyloarthritis (axSpA). The objectives were to study; 1) IgA anti-CD74 in radiographic (r)-axSpA patients in the Backbone cohort and to calculate the sensitivity and specificity of anti-CD74, 2) the fluctuation of IgA anti-CD74 levels in prospectively collected samples, 3) and to explore the relation between IgA anti-CD74 and radiographic spinal changes. METHODS:IgA anti-CD74 was analyzed by ELISA in 155 patients with r-axSpA and age- and sex-matched controls. BASDAI, ASDAS, BASFI, and BASMI were assessed and spinal radiographs were scored for r-axSpA related changes with mSASSS. Previously donated samples, before inclusion in the Backbone study, were identified in the Medical Biobank of Northern Sweden. RESULTS: A total of 155 patients comprising 69% men and 31% women, age (mean±SD) 55.5 ± 11.4 years, and 152 (98.1%) HLA-B27 positive, were included. The plasma level of IgA anti-CD74 was significantly higher in the patients, median (IQR), 12.9 (7.9-17.9) U/ml compared with controls 10.9 (7.2-14.6) U/ml, p= 0.003. IgA anti-CD74 was above the cut-off level of 20 U/ml in 36/155 (23.2%) patients and in 15/151 (9.9%) controls, p= 0.002. Multivariable logistic regression analyzes revealed that to have ≥1 syndesmophyte associated with IgA anti-CD74 (OR 5.64, 95% CI, 1.02-35.58, p= 0.048) adjusted for hsCRP, smoking, BMI, sex, and age. No distinct pattern of IgA anti-CD74 over time was revealed. CONCLUSION: Plasma levels of IgA anti-CD74 were increased in r-axSpA and independently associated with radiographic spinal changes which suggests that IgA anti-CD74 could play a role in the pathogenies of r-axSpA.