Pathogenic Citrulline-Multispecific B Cell Receptor Clades in Rheumatoid Arthritis

Philip J. Titcombe, Gustaf Wigerblad, Natalie Sippl, Na Zhang, Anna K Shmagel, Peter Sahlström, Yue Zhang, Laura O. Barsness, Yogita Ghodke-Puranik, Azar Baharpoor, Monika Hansson, Lena Israelsson, Karl Skriner, Timothy B. Niewold, Lars Klareskog, Camilla I. Svensson, Khaled Amara, Vivianne Malmström, Daniel L Mueller

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

Objective: Anti–citrullinated protein antibodies (ACPAs) have proven highly useful as biomarkers for rheumatoid arthritis (RA). However, composition and functionality of the associated autoreactive B cell repertoire have not been directly assessed. We aimed to selectively investigate citrullinated autoantigen–specific B cell receptors (BCRs) involved in RA and initiate studies on their pathogenicity. Methods: Blood samples were obtained from patients in a University of Minnesota cohort with ACPA-positive RA (n = 89). Tetramer sets bearing citrullinated filaggrin peptide cfc1 or citrullinated α-enolase peptide were constructed to specifically capture autoreactive B cells from the unaltered, polyclonal repertoire in RA patients. Citrullinated peptide tetramer–bound B cells were subjected to flow cytometric cell sorting and single-cell IGH, IGK, and IGL gene sequencing for B cell lineage determinations. BCR gene sequences were also expressed as recombinant monoclonal antibodies (mAb) for direct evaluation of citrullinated autoantigen binding and effector functionality. Results: Using citrullinated peptide tetramer enrichment to investigate single autoreactive blood B cells, we identified biased V-region gene usage and conserved junction arrangements in BCRs from RA patients. Parsimonious clustering of related immunoglobulin gene nucleotide sequences revealed clonal expansions of rare individual B cell clades, in parallel with divergent sequence mutations. Correspondingly, recombinant mAb generated from such BCR lineages demonstrated citrulline-dependent cross-reactivity extending beyond the citrullinated peptides used for B cell capture. A pair of citrullinated autoantigen–specific mAb with cross-reactive binding profiles also promoted arthritis in mice. Conclusion: Our findings suggest that broad ACPA specificities in RA arise from a restricted repertoire of evolving citrulline-multispecific B cell clades with pathogenic potential.

Original languageEnglish (US)
Pages (from-to)1933-1945
Number of pages13
JournalArthritis and Rheumatology
Volume70
Issue number12
DOIs
StatePublished - Dec 2018

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