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T Cell-Dependent Affinity Maturation and Innate Immune Pathways Differentially Drive Autoreactive B Cell Responses in Rheumatoid Arthritis.

ABSTRACT: OBJECTIVE:Rheumatoid arthritis (RA) is characterized by the activation of B cells that produce anti-citrullinated protein antibodies (ACPAs) and rheumatoid factors (RFs), but the mechanisms by which tolerance is broken in these B cells remain incompletely understood. We undertook this study to investigate whether ACPA+ and RF+ B cells break tolerance through distinct molecular mechanisms. METHODS:We developed antigen-tetramers to isolate ACPA+ and RF+ B cells and performed single-cell RNA sequencing on 2,349 B cells from 6 RA patients and 1 healthy donor to analyze their immunoglobulin repertoires and transcriptional programs. Prominent immunoglobulins were expressed as monoclonal antibodies and tested for autoantigen reactivity. RESULTS:ACPA+ and RF+ B cells were enriched in the peripheral blood of RA patients relative to healthy controls. Characterization of patient-derived monoclonal antibodies confirmed ACPA and RF targeting of tetramer-specific B cells at both antigen-inexperienced and affinity-matured B cell stages. ACPA+ B cells used more class-switched isotypes and exhibited more somatic hypermutations relative to RF+ B cells, and these differences were accompanied by down-regulation of CD72 and up-regulation of genes that promote class-switching and T cell-dependent responses. In contrast, RF+ B cells expressed transcriptional programs that stimulate rapid memory reactivation through multiple innate immune pathways. Coexpression analysis revealed that ACPA+ and RF+ B cell-enriched genes belong to distinct transcriptional regulatory networks. CONCLUSION:Our findings suggest that ACPA+ and RF+ B cells are imprinted with distinct transcriptional programs, which suggests that these autoantibodies associated with increased inflammation in RA arise from 2 different molecular mechanisms.

SUBMITTER: Lu DR

PROVIDER: S-EPMC6203609 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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T Cell-Dependent Affinity Maturation and Innate Immune Pathways Differentially Drive Autoreactive B Cell Responses in Rheumatoid Arthritis.

Lu Daniel R DR McDavid Andrew N AN Kongpachith Sarah S Lingampalli Nithya N Glanville Jacob J Ju Chia-Hsin CH Gottardo Raphael R Robinson William H WH

Arthritis & rheumatology (Hoboken, N.J.) 20180924 11

<h4>Objective</h4>Rheumatoid arthritis (RA) is characterized by the activation of B cells that produce anti-citrullinated protein antibodies (ACPAs) and rheumatoid factors (RFs), but the mechanisms by which tolerance is broken in these B cells remain incompletely understood. We undertook this study to investigate whether ACPA+ and RF+ B cells break tolerance through distinct molecular mechanisms.<h4>Methods</h4>We developed antigen-tetramers to isolate ACPA+ and RF+ B cells and performed single- ...[more]

PMID: 29855173

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Project description:ObjectiveRheumatoid arthritis (RA) is characterized by the presence of anti-citrullinated protein antibodies (ACPAs); nevertheless, the origin, specificity, and functional properties of ACPAs remain poorly understood. The aim of this study was to characterize the evolution of ACPAs by sequencing the plasmablast antibody repertoire at serial time points in patients with established RA.MethodsBlood samples were obtained at up to 4 serial time points from 8 individuals with established RA who were positive for ACPAs by the anti-cyclic citrullinated peptide test. CD19+CD3-IgD-CD14-CD20-CD27+CD38++ plasmablasts were isolated by single-cell sorting and costained with citrullinated peptide tetramers to identify ACPA-expressing plasmablasts. Cell-specific oligonucleotide barcodes were utilized, followed by large-scale sequencing and bioinformatics analysis, to obtain error-corrected, paired heavy- and light-chain antibody gene sequences for each B cell.ResultsBioinformatics analysis revealed 170 persistent plasmablast lineages in the RA blood, of which 19% included multiple isotypes. Among IgG- and IgA-expressing plasmablasts, significantly more IgA-expressing than IgG-expressing persistent lineages were observed (P < 0.01). Shared complementarity-determining region 3 sequence motifs were identified across subjects. A subset of the plasmablast lineages included members derived from later time points with divergent somatic hypermutations that encoded antibodies that bind an expanded set of citrullinated antigens. Furthermore, these recombinant, differentially mutated plasmablast antibodies formed immune complexes that stimulated higher macrophage production of tumor necrosis factor (TNF) compared to antibodies representing earlier time point-derived lineage members that were less mutated.ConclusionThese findings demonstrate that established RA is characterized by a persistent IgA ACPA response that exhibits ongoing affinity maturation. This observation suggests the presence of a persistent mucosal antigen that continually promotes the production of IgA plasmablasts and their affinity maturation and epitope spreading, thus leading to the generation of ACPAs that bind additional citrullinated antigens and more potently stimulate macrophage production of TNF.

Dataset Information

T Cell-Dependent Affinity Maturation and Innate Immune Pathways Differentially Drive Autoreactive B Cell Responses in Rheumatoid Arthritis.

Publications

T Cell-Dependent Affinity Maturation and Innate Immune Pathways Differentially Drive Autoreactive B Cell Responses in Rheumatoid Arthritis.

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