Autoimmune rheumatologic diseases

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Sequencing the Plasmablast Antibody Repertoire at Serial Time Points Reveals Affinity Maturation That Drives Epitope Spreading in Rheumatoid Arthritis

Friday, June 16
6:15 PM - 7:30 PM

Rheumatoid arthritis (RA) is characterized by autoantibodies targeting citrullinated antigens, nevertheless the precise specificity and functional properties of anti-citrullinated protein antibodies (ACPAs) remain poorly understood. We sequenced the blood plasmablast antibody repertoire at serial time points to characterize the affinity maturation of key ACPA and gain insight into pathogenic mechanisms underlying RA. To profile the autoantibody repertoire, we used a cell barcoding technology that enables sequencing of the full-length, paired heavy and light chain genes expressed by individual B cells. This enables direct linkage of sequence information with antibody specificity through recombinant expression. We sorted and sequenced plasmablasts from peripheral blood sampled at up to four time points from eight individuals with established RA and used a citrullinated peptide-based sort reagent to isolate plasmablasts expressing ACPA. Bioinformatics analysis identified clonal lineages that persisted across serial time points, some of which share similar CDR3 sequences across patients, and characterized their expansion and contraction. Recombinant antibodies representative of the plasmablast clonal families were expressed and characterized using in vitro assays to define their antigen targets and compare immune complex stimulation of TNF production from macrophages. Certain clonal family members from later time points possessed higher levels of somatic hypermutation and demonstrated binding to an expanded set of antigen targets as compared to earlier family members. Our work provides evidence that affinity maturation of ACPA-encoding B cell lineages drives epitope spreading in individuals with established RA.

Serra E. Elliott

Postdoctoral Fellow
Stanford University; VA Palo Alto Health Care System

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    Sarah Kongpachith

    Stanford University; VA Palo Alto Health Care System

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      Nithya Lingampalli

      Stanford University; VA Palo Alto Health Care System

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        Lisa Blum

        Stanford University; VA Palo Alto Health Care System

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          Julia Z. Adamska

          Stanford University; VA Palo Alto Health Care System

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            William H. Robinson

            Stanford University; VA Palo Alto Health Care System

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