1. Affinity-matured ‘aquaporumab’ anti-aquaporin-4 antibody for therapy of seropositive neuromyelitis optica spectrum disorders
- Author
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Duan, Tianjiao, Tradtrantip, Lukmanee, Phuan, Puay-Wah, Bennett, Jeffrey L, and Verkman, Alan S
- Subjects
Autoimmune Disease ,Neurosciences ,Eye Disease and Disorders of Vision ,Biotechnology ,Aetiology ,2.1 Biological and endogenous factors ,Animals ,Antibodies ,Blocking ,Antibodies ,Monoclonal ,Antibody Affinity ,Antibody-Dependent Cell Cytotoxicity ,Aquaporin 4 ,Autoantibodies ,Binding ,Competitive ,CHO Cells ,Cell Survival ,Complement System Proteins ,Cricetulus ,Cytotoxicity Tests ,Immunologic ,Humans ,Immunoglobulin G ,Killer Cells ,Natural ,Mutagenesis ,Neuromyelitis Optica ,Recombinant Proteins ,Serum ,NMOSD ,Autoimmunity ,Blocking antibody ,AQP4 ,Astrocyte ,Pharmacology and Pharmaceutical Sciences ,Psychology ,Neurology & Neurosurgery - Abstract
Pathogenesis in seropositive neuromyelitis optica spectrum disorders (herein called NMO) involves binding of IgG1 autoantibodies to aquaporin-4 (AQP4) on astrocytes in the central nervous system, which initiates complement and cellular injury. We previously developed an antibody blocking approach for potential therapy of NMO in which an engineered, monoclonal, anti-AQP4 antibody lacking cytotoxicity effector functions (called aquaporumab) blocked binding of NMO autoantibodies to astrocyte AQP4 (Tradtrantip et al. Ann. Neurol. 71, 314-322, 2012). Here, a high-affinity aquaporumab, which was generated by affinity maturation using saturation mutagenesis, was shown to block cellular injury caused by NMO patient sera. Anti-AQP4 antibody rAb-53, a fully human antibody with effector function neutralizing Fc mutations L234A/L235A and affinity-enhancing Fab mutations Y50R/S56R, called AQmabAM, bound to AQP4 in cell cultures with Kd ~ 18 ng/ml (~0.12 nM), ~8-fold greater affinity than the original antibody. AQmabAM, but without L234A/L235A Fc mutations, produced complement-dependent cytotoxicity (CDC) with EC50 ~ 82 ng/ml. AQmabAM prevented CDC produced by sera from eight NMO patients with IC50 ranging from 40 to 80 ng/ml, and similarly prevented antibody-dependent cellular cytotoxicity (ADCC). Mechanistic studies demonstrated that AQmabAM blocked binding of serum NMO autoantibodies to AQP4. AQmabAM offers a targeted, non-immunosuppressive approach for therapy of seropositive NMO. Autoantibody blocking may be a useful therapeutic strategy for other autoimmune diseases as well.
- Published
- 2020