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- Hensvold, Aase, et al.
(författare)
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The human bone marrow plasma cell compartment in rheumatoid arthritis-Clonal relationships and anti-citrulline autoantibody producing cells
- 2023
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Ingår i: Journal of Autoimmunity. - : Elsevier BV. - 0896-8411 .- 1095-9157. ; 136
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Tidskriftsartikel (refereegranskat)abstract
- A majority of circulating IgG is produced by plasma cells residing in the bone marrow (BM). Long-lived BM plasma cells constitute our humoral immune memory and are essential for infection-specific immunity. They may also provide a reservoir of potentially pathogenic autoantibodies, including rheumatoid arthritis (RA)-associated anti-citrullinated protein autoantibodies (ACPA). Here we investigated paired human BM plasma cell and peripheral blood (PB) B-cell repertoires in seropositive RA, four ACPA+ RA patients and one ACPA- using two different single-cell approaches, flow cytometry sorting, and transcriptomics, followed by recombinant antibody generation. Immunoglobulin (Ig) analysis of >900 paired heavy-light chains from BM plasma cells identified by either surface CD138 expression or transcriptome profiles (including gene expression of MZB1, JCHAIN and XBP1) demonstrated differences in IgG/A repertoires and N-linked glycosylation between patients. For three patients, we identified clonotypes shared between BM plasma cells and PB memory B cells. Notably, four individuals displayed plasma cells with identical heavy chains but different light chains, which may indicate receptor revision or clonal convergence. ACPA-producing BM plasma cells were identified in two ACPA+ patients. Three of 44 recombinantly expressed monoclonal antibodies from ACPA+ RA BM plasma cells were CCP2+, specifically binding to citrullinated peptides. Out of these, two clones reacted with citrullinated histone-4 and activated neutrophils. In conclusion, single-cell investigation of B-cell repertoires in RA bone marrow provided new understanding of human plasma cells clonal relationships and demonstrated pathogenically relevant disease-associated autoantibody expression in long-lived plasma cells.
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- Sherina, Natalia, et al.
(författare)
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Antibodies to a Citrullinated Porphyromonas gingivalis Epitope Are Increased in Early Rheumatoid Arthritis, and Can Be Produced by Gingival Tissue B Cells : Implications for a Bacterial Origin in RA Etiology
- 2022
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Ingår i: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Based on the epidemiological link between periodontitis and rheumatoid arthritis (RA), and the unique feature of the periodontal bacterium Porphyromonas gingivalis to citrullinate proteins, it has been suggested that production of anti-citrullinated protein antibodies (ACPA), which are present in a majority of RA patients, may be triggered in the gum mucosa. To address this hypothesis, we investigated the antibody response to a citrullinated P. gingivalis peptide in relation to the autoimmune ACPA response in early RA, and examined citrulline-reactivity in monoclonal antibodies derived from human gingival B cells. Antibodies to a citrullinated peptide derived from P. gingivalis (denoted CPP3) and human citrullinated peptides were analyzed by multiplex array in 2,807 RA patients and 372 controls; associations with RA risk factors and clinical features were examined. B cells from inflamed gingival tissue were single-cell sorted, and immunoglobulin (Ig) genes were amplified, sequenced, cloned and expressed (n=63) as recombinant monoclonal antibodies, and assayed for citrulline-reactivities by enzyme-linked immunosorbent assay. Additionally, affinity-purified polyclonal anti-cyclic-citrullinated peptide (CCP2) IgG, and monoclonal antibodies derived from RA blood and synovial fluid B cells (n=175), were screened for CPP3-reactivity. Elevated anti-CPP3 antibody levels were detected in RA (11%), mainly CCP2+ RA, compared to controls (2%), p<0.0001, with a significant association to HLA-DRB1 shared epitope alleles, smoking and baseline pain, but with low correlation to autoimmune ACPA fine-specificities. Monoclonal antibodies derived from gingival B cells showed cross-reactivity between P. gingivalis CPP3 and human citrullinated peptides, and a CPP3+/CCP2+ clone, derived from an RA blood memory B cell, was identified. Our data support the possibility that immunity to P. gingivalis derived citrullinated antigens, triggered in the inflamed gum mucosa, may contribute to the presence of ACPA in RA patients, through mechanisms of molecular mimicry.
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- Sippl, Natalie
(författare)
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Exploring lymphocyte subsets, autoantibodies and the effect of B cell targeted therapies in rheumatic diseases
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nowadays, around 100 different diseases sort under the umbrella of rheumatic diseases(1). They involve different mechanisms and symptoms engaging joints, tendons, ligaments, bones, muscles but also vital organs like the kidneys nervous system and circulation. The diagnoses is dependent on a combination of common clinical manifestations and laboratory findings such as the presence of specific antibodies that target self-antigen (2–4). Rheumatic disease evolves from a complex interplay between genetic, stochastic and environmental factors resulting in a loss of immune tolerance. B-cell targeting agents have proven useful in the treatment of several rheumatic diseases. Rituximab, a chimeric monoclonal antibody targeting CD20, is e.g. used in rheumatoid arthritis (RA) patients who do not respond to tumor necrosis factor (TNF) inhibitors and as off label-rescue treatment in systemic lupus erythematosus (SLE). Additionally, belimumab, a B cell activating factor (BAFF) inhibitor, is the first approved biological drug for SLE. Even though B-cell targeting therapies are commonly used, little is known about the effect of these therapies on disease associated B and T cell subsets, such as age/autoimmune-associated B cells (ABCs) and T follicular helper (Tfh) cells. In paper I, we therefore studied the effect of these two subsets in response to rituximab treatment in SLE patients and found that ABCs are indeed influenced by the treatment while Tfh frequencies stayed similar to baseline. Additionally, we observed a decrease frequency of programmed cell death protein 1 (PD-1) high CD4+ T cells. In paper II, we investigated the effect of belimumab on circulating B and T cell phenotypes in SLE patients using mass cytometry and correlated them with clinical response. Belimumab had rapid effects on B cell subsets of earlier developmental stages such as naïve B cells while late B cell stages, such as memory or plasma cells, decreased later in a gradual manner or did not change upon treatment. Only early immunological changes correlated with disease improvement. High B cell counts at baseline were associated with late or non-responders. Not all patients respond to B-cell targeting therapy, highlighting the heterogenicity of SLE. To develop novel therapies, a better understanding of the underlying mechanisms related to clinical phenotypes is needed. Thus, in paper III, we explored the cytokine profile and the cellular composition in the synovial fluid of lupus arthritis patients, and we found elevated levels of IL-6 and IL-17A in the joint. Furthermore, we found an enrichment of Th17, peripheral helper T cells and EOMES/Granzyme A-expressing T cells in synovial fluid of SLE patients. All in all, indicating a potential role of Th17 cells in the pathogenesis of lupus. In contrast to lupus arthritis, RA patients exhibit a more aggressive form of arthritis, especially in conjunction with anti-citrullinated protein autoantibodies (ACPA). Therefore, in paper IV, we investigated the citrulline-specific B cell population in RA patients using an antigen-tetramer enrichment technology followed by single cell sequencing of the immunoglobulin genes. We discovered that the broad ACPA specificity in RA patients might develop from clonal expansion of a few B cell clones. Furthermore, monoclonal antibodies which originated from citrulline reactive B cells were multi-reactive and able to promote pain-like behavior and joint inflammation in mice. Overall, this thesis explored immunological changes upon B-cell-targeting therapy and pathogenicity in joint inflammation in SLE and seropositive RA patients. We provided new understanding of B-cell targeting therapies on B and T cell subsets in SLE patients as well as the pathogenic mechanism which might be involved in lupus arthritis. Additionally, we examined the citrulline reactive B cell repertoire in RA patients and our data reveal their potential origin.
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