Pathogenic Citrulline‐Multispecific B Cell Receptor Clades in Rheumatoid Arthritis. Issue 12 (18th October 2018)

• Record Type: Journal Article
• Authors: Titcombe, Philip J.; Wigerblad, Gustaf; Sippl, Natalie; Zhang, Na; Shmagel, Anna K.; Sahlström, Peter; Zhang, Yue; Barsness, Laura O.; Ghodke‐Puranik, Yogita; Baharpoor, Azar; Hansson, Monika; Israelsson, Lena; Skriner, Karl; Niewold, Timothy B.; Klareskog, Lars; Svensson, Camilla I.; Amara, Khaled; Malmström, Vivianne; Mueller, Daniel L.
• Is Part Of: Arthritis & rheumatology. Volume 70:Issue 12(2018)
• Page Start: 1933
• Page End: 1945
• Publication Date: 2018-10-18
• Subjects: Arthritis -- Periodicals; Rheumatism -- Periodicals; 616.72
• DOI: 10.1002/art.40590
• Languages: English
• ISSNs: 2326-5191

Abstract

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.