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- Andersson, Maria L.E., et al.
(author)
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Autoantibodies to Disease-Related Proteins in Joints as Novel Biomarkers for the Diagnosis of Rheumatoid Arthritis
- 2023
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In: Arthritis & Rheumatology. - : Wiley. - 2326-5191 .- 2326-5205. ; 75:7, s. 1110-1119
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Journal article (peer-reviewed)abstract
- Objective. This study was undertaken to develop and characterize a multiplex immunoassay for detection of autoantibodies against peptides derived from proteins known to play a role in development of arthritis and that are also expressed in joints.Methods. We selected peptides from the human counterpart of proteins expressed in the joints, based on mouse models that showed these to be targeted by pathogenic or regulatory antibodies in vivo. Using bead-based flow immunoassays measuring IgG antibodies, we selected triple helical or cyclic peptides, containing the epitopes, to avoid collinear reactivity. We characterized the analytical performance of the immunoassay and then validated it in 3 independent rheumatoid arthritis (RA) cohorts (n = 2,110), Swedish age- and sex-matched healthy controls, and patients with osteoarthritis (OA), patients with psoriatic arthritis (PsA), and patients with systemic lupus erythematosus (SLE).Results. Screening assays showed 5 peptide antigens that discriminated RA patients from healthy controls with 99% specificity (95% confidence interval [CI] 98-100%). In our validation studies, we reproduced the discriminatory capacity of the autoantibodies in 2 other RA cohorts, showing that the autoantibodies had high discriminatory capacity for RA versus OA, PsA, and SLE. The novel biomarkers identified 22.5% (95% CI 19-26%) of early RA patients seronegative for anti-cyclic citrullinated peptide and rheumatoid factor. The usefulness of the biomarkers in identifying seronegative RA patients was confirmed in validation studies using 2 independent cohorts of RA patients and cohorts of patients with OA, PsA, and SLE.Conclusion. A multiplex immunoassay with peptides from disease-related proteins in joints was found to be useful for detection of specific autoantibodies in RA serum. Of note, this immunoassay had high discriminatory capacity for early seronegative RA.
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| 2. |
- Gatto, Mariele, et al.
(author)
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Early increase of circulating transitional B cells and autoantibodies to joint-related proteins in patients with metastatic melanoma developing checkpoint inhibitor-induced inflammatory arthritis.
- 2023
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In: Arthritis & rheumatology (Hoboken, N.J.). - : Wiley. - 2326-5205 .- 2326-5191. ; 75:5, s. 856-863
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Journal article (peer-reviewed)abstract
- To investigate potential associations between B cell-related immunological changes and development of inflammatory arthritis (IA) after treatment with immune checkpoint inhibitors (ICI).Patients who developed IA (ICI-IA) and patients who did not develop immune-related adverse events (non-irAE) after receiving ICI due to metastatic melanoma were consecutively recruited. Blood samples were collected at the time of ICI-IA occurrence and at different timepoints during treatment. Peripheral blood B cell subsets during ICI treatment were analyzed by flow cytometry. Rheumatoid factor, autoantibodies against citrullinated peptides and against joint-related proteins were measured.Proportions of CD19+ B cells were higher in patients with ICI-IA (n=7) vs. non-irAE (n=15; median (interquartile range, IQR), %: 11.7 (9.7-16.2) vs. 8.1 (5.7-11.0), p=0.03). The proportion and absolute numbers of transitional CD19+ CD10+ CD24hi CD38hi B cells were increased in patients with ICI-IA vs. non-irAE (median (IQR); %: 8.1 (4.9-12.1) vs. 3.6 (1.9-4.9); cells/μl: 10.7 (8.9-19.6) vs. 4.4 (2.3-6.6), p<0.01 for both), and higher levels of transitional B cells were associated with development of ICI-IA (OR 95% CI: 2.25 (1.03-4.9), p=0.04). Transitional B cells increased before the onset of overt ICI-IA and decreased from active to quiescent ICI-IA (p=0.02). Autoantibodies to collagen II epitopes were detected in up to 43% of ICI-IA patients compared to none of the non-irAE patients (p=0.02).Development of ICI-IA is accompanied by an increase in transitional B cells and by production of autoantibodies to joint-related proteins. Monitoring of B cell-driven abnormalities upon ICI treatment may help earlier recognition of ICI-IA. This article is protected by copyright. All rights reserved.
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| 3. |
- Li, T. T., et al.
(author)
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Pathogenic antibody response to glucose-6-phosphate isomerase targets a modified epitope uniquely exposed on joint cartilage
- 2023
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In: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 82:6, s. 799-808
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Journal article (peer-reviewed)abstract
- ObjectivesTo identify the arthritogenic B cell epitopes of glucose-6-phosphate isomerase (GPI) and their association with rheumatoid arthritis (RA). MethodsIgG response towards a library of GPI peptides in patients with early RA, pre-symptomatic individuals and population controls, as well as in mice, were tested by bead-based multiplex immunoassays and ELISA. Monoclonal IgG were generated, and the binding specificity and affinity were determined by ELISA, gel size exclusion chromatography, surface plasma resonance and X-ray crystallography. Arthritogenicity was investigated by passive transfer experiments. Antigen-specific B cells were identified by peptide tetramer staining. ResultsPeptide GPI(293-307) was the dominant B cell epitope in K/BxN and GPI-immunised mice. We could detect B cells and low levels of IgM antibodies binding the GPI(293-307) epitopes, and high affinity anti-GPI(293-307) IgG antibodies already 7 days after GPI immunisation, immediately before arthritis onset. Transfer of anti-GPI(293-307) IgG antibodies induced arthritis in mice. Moreover, anti-GPI(293-307) IgG antibodies were more frequent in individuals prior to RA onset (19%) than in controls (7.5%). GPI(293-307)-specific antibodies were associated with radiographic joint damage. Crystal structures of the Fab-peptide complex revealed that this epitope is not exposed in native GPI but requires conformational change of the protein in inflamed joint for effective recognition by anti-GPI(293-307) antibodies. ConclusionsWe have identified the major pathogenic B cell epitope of the RA-associated autoantigen GPI, at position 293-307, exposed only on structurally modified GPI on the cartilage surface. B cells to this neo-epitope escape tolerance and could potentially play a role in the pathogenesis of RA.
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