A Novel Fusion Protein, AChR-Fc, Ameliorates Myasthenia Gravis by Neutralizing Antiacetylcholine Receptor Antibodies and Suppressing Acetylcholine Receptor-Reactive B Cells.

Most patients with myasthenia gravis (MG) have elevated levels of autoantibodies against the nicotinic acetylcholine receptor (AChR) at the neuromuscular junction, which leads to muscle weakness. We developed a fusion protein, AChR-Fc, as a novel therapeutic biomolecule for patients with MG and examined its efficacy. AChR-Fc was expressed by Chinese hamster ovary cells and purified. We examined the neutralizing activity and cellular cytotoxicity of AChR-Fc using anti-AChR antibody-producing hybridoma cells and serum samples from 16 patients with MG. The effects of AChR-Fc in vivo were also examined using rat MG models. AChR-Fc bound to anti-AChR antibodies and exhibited cytotoxicity against patient-derived antibody-producing B cells. Additionally, a dose-dependent improvement in the clinical signs of disease was observed in a rat MG model. AChR-Fc can diminish signs of MG by neutralizing anti-AChR antibodies and enhancing cytotoxicity against autoantibody-producing B cells. Thus, AChR-Fc can be a novel therapeutic biomolecule for patients with MG.