Selective recognition and elimination of nicotinic acetylcholine receptor-reactive B cells by a recombinant fusion protein AChR-Fc in myasthenia gravis in vitro

Abstract 

AChR-reactive B cells play a key role in the pathogenesis of myasthenia gravis (MG) by producing autoantibodies. Selective elimination of AChR-reactive B cells will be a promising way to treat MG. Thus, we generated a fusion protein (referred to as AChR-Fc) composed of the human extracellular domain of AChR α1 subunit and the Fc domain of the human IgG1 heavy chain, which could bind both to AChR-reactive BCR and FcγRIIB on the surface of AChR-reactive B cells. Our results showed that AChR-Fc inhibited the proliferation of AChR-specific hybridoma cells, promoted their apoptosis, and mediated cytotoxicity by cross-linking effector cells and complement. Likewise, AChR-Fc significantly reduced the number of AChR-reactive B cells from spleen of Lewis rats immunized with AChR ex vivo.

Abbreviations: AChE, acetylcholinesterase, AChR, nicotinic acetylcholine receptor, ANOVA, one-way analysis of variance, BCR, B cell receptor, BrdU, bromodeoxyuridine, EAMG, experimental autoimmune myasthenia gravis, ELISA, enzyme-linked immunosorbent assay, FACS, fluorescence-activated cell sorter, Hα1–210, extracellular domain of AChR α1 subunit, IVIG, intravenous immunoglobulin, KO, knock out, MG, myasthenia gravis, MIR, main immunogenic region, MS, multiple sclerosis, N.C., negative control, NMJ, neuromuscular junction, PBMC, peripheral blood mononuclear cell, RA, rheumatoid arthritis, SLE, systemic lupus erythematosus, TAChR, torpedo acetylcholine receptor, WT, wild type

Keywords: Myasthenia gravis, Autoantibodies, Autoimmunity, Fusion protein