@article{d0cfbfa8ef17487aa9137083fead1c0b,
title = "Reemergence of pathogenic, autoantibody-producing B cell clones in myasthenia gravis following B cell depletion therapy",
abstract = "Myasthenia gravis (MG) is an autoantibody-mediated autoimmune disorder of the neuromuscular junction. A small subset of patients (<10%) with MG, have autoantibodies targeting muscle-specific tyrosine kinase (MuSK). MuSK MG patients respond well to CD20-mediated B cell depletion therapy (BCDT); most achieve complete stable remission. However, relapse often occurs. To further understand the immunomechanisms underlying relapse, we studied autoantibody-producing B cells over the course of BCDT. We developed a fluorescently labeled antigen to enrich for MuSK-specific B cells, which was validated with a novel Nalm6 cell line engineered to express a human MuSK-specific B cell receptor. B cells ( approximately equal to 2.6 million) from 12 different samples collected from nine MuSK MG patients were screened for MuSK specificity. We successfully isolated two MuSK-specific IgG4 subclass-expressing plasmablasts from two of these patients, who were experiencing a relapse after a BCDT-induced remission. Human recombinant MuSK mAbs were then generated to validate binding specificity and characterize their molecular properties. Both mAbs were strong MuSK binders, they recognized the Ig1-like domain of MuSK, and showed pathogenic capacity when tested in an acetylcholine receptor (AChR) clustering assay. The presence of persistent clonal relatives of these MuSK-specific B cell clones was investigated through B cell receptor repertoire tracing of 63,977 unique clones derived from longitudinal samples collected from these two patients. Clonal variants were detected at multiple timepoints spanning more than five years and reemerged after BCDT-mediated remission, predating disease relapse by several months. These findings demonstrate that a reservoir of rare pathogenic MuSK autoantibody-expressing B cell clones survive BCDT and reemerge into circulation prior to manifestation of clinical relapse. Overall, this study provides both a mechanistic understanding of MuSK MG relapse and a valuable candidate biomarker for relapse prediction.",
keywords = "Myasthenia gravis, Muscle-specific tyrosine kinase (MuSK), B cells, Autoantibodies, B cell depletion therapy, Rituximab, ACETYLCHOLINE-RECEPTOR ANTIBODY, SYSTEMIC-LUPUS-ERYTHEMATOSUS, CHIMERIC ANTIGEN RECEPTOR, ACTIVATING FACTOR, TOLERANCE CHECKPOINTS, IGG4 AUTOANTIBODIES, PERIPHERAL-BLOOD, MUSK, RITUXIMAB, EXPRESSION",
author = "M.L. Fichtner and K.B. Hoehn and E.E. Ford and M. Mane-Damas and S. Oh and P. Waters and A.S. Payne and M.L. Smith and C.T. Watson and M. Losen and P. Martinez-Martinez and R.J. Nowak and S.H. Kleinstein and K.C. O'Connor",
note = "Funding Information: MLF is supported through a DFG Research fellowship (FI 2471/1-1). KCO is supported by the National Institute of Allergy and Infectious Diseases of the NIH under award numbers R01-AI114780 and R21-AI142198, and through an award provided through the Rare Diseases Clinical Research Consortia of the NIH and MGNet (award number U54-NS115054). SHK is supported by the National Institute of Allergy and Infectious Diseases of the NIH under award number R01AI104739. PMM and MMD were supported by the the Kootstra Talent Fellowship (Fall 2019, Maastricht University) and the ZonMW/NWO Aspasia Program [grant number 015.011.033] and a NIH grant (R21-AI142198). ASP and SO were supported by sponsored research from Cabaletta Bio. The funders had no role in the decision to publish or preparation of the manuscript. Funding Information: KCO has received research support from Alexion, now part of AstraZeneca, and Viela Bio, now part of Horizon Therapeutics, and Cabaletta Bio. KCO is a consultant and equity shareholder of Cabaletta Bio. During the last two years, KCO has served as consultant/advisor for Alexion Pharmaceuticals, now part of AstraZeneca, and for Roche, and he has received speaking fees from Alexion, Roche, Genentech, Viela Bio, now part of Horizon Therapeutics, and UCB. MLF received a SPIN award from Grifols outside the submitted work and is a member of the Alexion-Akademie. KBH receives consulting fees from Prellis Biologics. SHK receives consulting fees from Peraton. ASP has received equity, research support, patent licensing and other payments from Cabaletta Bio; patent licensing payments from Novartis; and consultant fees from Janssen. SO has received patent licensing payments from Cabaletta Bio. The research of PMM and MMD at the School of Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences was financially supported by Apellis, Argenx, Genmab, Neurotune and Takeda. PMM is a co-inventor of the following patent: Use of effector-function-deficient antibodies for treatment of auto-immune diseases (Patent number: 9181344). These competing interests played no role in the research design, reference collection, decision to publish, or preparation of the manuscript. Funding Information: We thank Dr. Gianvito Masi for critical reading of the manuscript, Drs. Lesley Devine and Chao Wang in the Yale Flow Cytometry Core for their assistance with cell sorting, and Lindsay Young for administrative support. The Yale Flow Cytometry Core is supported in part by an NCI Cancer Center Support Grant # NIH P30 CA016359. We also thank Yale Center for Genome Analysis and Keck Microarray Shared Resource for providing the necessary Pacific Biosciences sequencing services, which is funded, in part, by the National Institutes of Health instrument grant 1S10OD028669-01. Publisher Copyright: {\textcopyright} 2022, The Author(s).",
year = "2022",
month = oct,
day = "28",
doi = "10.1186/s40478-022-01454-0",
language = "English",
volume = "10",
journal = "Acta neuropathologica communications",
issn = "2051-5960",
publisher = "BioMed Central Ltd",
number = "1",
}