| 1. |
- 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. |
- Fahlquist-Hagert, Cecilia, et al.
(author)
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Variants of beta-glucan polysaccharides downregulate autoimmune inflammation
- 2022
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In: COMMUNICATIONS BIOLOGY. - : Springer Science and Business Media LLC. - 2399-3642. ; 5:1
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Journal article (peer-reviewed)abstract
- Common infections and polysaccharides, from bacteria and yeasts, could trigger psoriasis and psoriatic arthritis (PsA), and possibly rheumatoid arthritis (RA). The objective of this study was to investigate the effects of beta-glucan polysaccharides in the effector phase of arthritis and as regulators of psoriasis and PsA-like symptoms in mice. Collagen antibody induced arthritis was studied as a model of RA and mannan-induced psoriasis (MIP) was used as model for psoriasis and PsA, using mice with a mutation of Ncf1 on the B10.Q genetic background, making them highly disease susceptible. The mice were exposed to three common variants: 1,6-beta-glucan, 1,3-beta-glucan and 1,3-1,6-beta-glucan. These beta-glucans down-regulated disease in mice if administered simultaneously, before or after mannan. Interestingly, the protection was macrophage mannose receptor (MMR/CD206) dependent with a more pronounced protection long-term than short-term. The number of resident peritoneal macrophages decreased after in vivo challenge with beta-glucan and mannan compared to mannan alone, whereas the numbers of infiltrating cells correspondingly increased, further indicating macrophages as key for beta-glucan mediated regulation. At the doses tested, beta-glucans could not induce arthritis, psoriasis or PsA in wild-type mice. However, beta-glucans could ameliorate the PsA-like symptoms representing a new unforeseen possibility to explore for future clinical treatment. beta-glucan exerted anti-inflammatory activities in a murine model of psoriasis and psoriatic arthritis is, at least in part, mediated via the activation of CD206 on macrophages
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| 3. |
- 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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| 4. |
- Hultqvist, Malin, et al.
(author)
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Positioning of a Polymorphic Quantitative Trait Nucleotide in the Ncf1 Gene Controlling Oxidative Burst Response and Arthritis Severity in Rats
- 2011
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In: Antioxidants and Redox Signaling. - : Mary Ann Liebert Inc. - 1523-0864 .- 1557-7716. ; 14:12, s. 2373-2383
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Journal article (peer-reviewed)abstract
- The Ncf1 gene, encoding the P47(PHOX) protein that regulates production of reactive oxygen species (ROS) by the phagocyte NADPH oxidase (NOX2) complex, is associated with autoimmunity and arthritis severity in rats. We have now identified that the single-nucleotide polymorphism (SNP) resulting in an M153T amino acid substitution mediates arthritis resistance and thus explains the molecular polymorphism underlying the earlier identified Ncf1 gene effect. We identified the SNP in position 153 to regulate ROS production using COSPHOX cells transfected with mutated Ncf1. To determine the role of this SNP for control of arthritis, we used the Wistar strain, identified to carry only the postulated arthritis resistant SNP in position 153. When this Ncf1 allele was backcrossed to the arthritis susceptible DA strain, both granulocyte ROS production and arthritis resistance were restored. Position 153 is located in the hinge region between the PX and SH3 domains of P47(PHOX). Mutational analysis of this position revealed a need for an -OH group in the side chain but we found no evidence for phosphorylation. The polymorphism did not affect assembly of the P47(PHOX)/P67(PHOX) complex in the cytosol or membrane localization, but is likely to operate downstream of assembly, affecting activity of the membrane NOX2 complex.
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| 5. |
- 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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| 6. |
- Romero-Castillo, Laura, et al.
(author)
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Human MHC Class II and Invariant Chain Knock-in Mice Mimic Rheumatoid Arthritis with Allele Restriction in Immune Response and Arthritis Association
- 2024
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In: Advanced Science. - 2198-3844.
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Journal article (peer-reviewed)abstract
- Transgenic mice expressing human major histocompatibility complex class II (MHCII) risk alleles are widely used in autoimmune disease research, but limitations arise due to non-physiologic expression. To address this, physiologically relevant mouse models are established via knock-in technology to explore the role of MHCII in diseases like rheumatoid arthritis. The gene sequences encoding the ectodomains are replaced with the human DRB1*04:01 and 04:02 alleles, DRA, and CD74 (invariant chain) in C57BL/6N mice. The collagen type II (Col2a1) gene is modified to mimic human COL2. Importantly, DRB1*04:01 knock-in mice display physiologic expression of human MHCII also on thymic epithelial cells, in contrast to DRB1*04:01 transgenic mice. Humanization of the invariant chain enhances MHCII expression on thymic epithelial cells, increases mature B cell numbers in spleen, and improves antigen presentation. To validate its functionality, the collagen-induced arthritis (CIA) model is used, where DRB1*04:01 expression led to a higher susceptibility to arthritis, as compared with mice expressing DRB1*04:02. In addition, the humanized T cell epitope on COL2 allows autoreactive T cell-mediated arthritis development. In conclusion, the humanized knock-in mouse faithfully expresses MHCII, confirming the DRB1*04:01 alleles role in rheumatoid arthritis and being also useful for studying MHCII-associated diseases.
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| 7. |
- Sareila, Outi, et al.
(author)
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Reactive Oxygen Species Regulate Both Priming and Established Arthritis, but with Different Mechanisms
- 2017
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In: Antioxidants and Redox Signaling. - : Mary Ann Liebert Inc. - 1523-0864 .- 1557-7716. ; 27:18, s. 1473-1490
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Journal article (peer-reviewed)abstract
- Aims: Neutrophil cytosolic factor 1 (NCF1) is a key regulatory component of the phagocytic NOX2 complex, which produces reactive oxygen species (ROS). Polymorphism of the Ncf1 gene is associated with increased arthritis severity. In this study, we generated targeted Ncf1 knock-in mice with inducible Ncf1 expression and determined the critical time window during which the NOX2-derived ROS protect the mice from arthritis.Results: Targeted Ncf1 knock-in mice lacked NOX2-derived ROS, and in vivo allelic conversion of Ncf1 by the CreER(T2) recombinase led to full protein expression and ROS production within 10 days. Mice in which Ncf1 had been activated before immunization with type II collagen (CII) developed only mild clinical symptoms of collagen-induced arthritis (CIA), whereas the ROS-deficient littermates had severe arthritis. The functional Ncf1 restricted the expansion of IL-17A-producing T cells specific for the immunodominant CII peptide. When the Ncf1 gene was activated after the priming phase, Ncf1-dependent protection from autoimmune arthritis was still observed, together with a reduced number of splenic monocytes but it was not associated with alterations in peptide-specific T cell response. The Ncf1-deficient mice expressed pronounced interferon signature, which could be normalized by conditional expression of Ncf1 and was also present in the Ncf1-mutated mouse during arthritis.Innovation and Conclusion: Ncf1 deficiency has been known to predispose to autoimmunity in both humans and rodents. Our in vivo results point to a regulatory role of NOX2-derived ROS not only during priming but also during the effector phase of CIA, most likely via different mechanisms.
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