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Pathogenic Citrulline‐Multispecific B Cell Receptor Clades in Rheumatoid Arthritis
Author(s) -
Titcombe Philip J.,
Wigerblad Gustaf,
Sippl Natalie,
Zhang Na,
Shmagel Anna K.,
Sahlström Peter,
Zhang Yue,
Barsness Laura O.,
GhodkePuranik Yogita,
Baharpoor Azar,
Hansson Monika,
Israelsson Lena,
Skriner Karl,
Niewold Timothy B.,
Klareskog Lars,
Svensson Camilla I.,
Amara Khaled,
Malmström Vivianne,
Mueller Daniel L.
Publication year - 2018
Publication title -
arthritis and rheumatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.106
H-Index - 314
eISSN - 2326-5205
pISSN - 2326-5191
DOI - 10.1002/art.40590
Subject(s) - biology , breakpoint cluster region , antibody , b cell , citrullination , b cell receptor , molecular mimicry , microbiology and biotechnology , polyclonal antibodies , epitope , immunology , gene , genetics , citrulline , arginine , amino acid
Objective Anti–citrullinated protein antibodies ( ACPA s) 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 ( BCR s) 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 ( mA b) 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 BCR s 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 mA b 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 mA b 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.