Affinity-matured 'aquaporumab' anti-aquaporin-4 antibody for therapy of seropositive neuromyelitis optica spectrum disorders. (1st January 2020)

• Record Type: Journal Article
• Authors: Duan, Tianjiao; Tradtrantip, Lukmanee; Phuan, Puay-Wah; Bennett, Jeffrey L.; Verkman, Alan S.
• Is Part Of: Neuropharmacology. Volume 162(2020)
• Publication Date: 2020-01-01
• Subjects: NMOSD -- Autoimmunity -- Blocking antibody -- AQP4 -- Astrocyte; ADCC antibody-dependent cellular cytotoxicity -- AQmabAM affinity-matured aquaporumab -- AQmabIdeS IdeS-cleaved AQmabAM -- AQP4 aquaporin-4 -- AQP4-IgG aquaporin-4 immunoglobulin G -- BSA bovine serum albumin -- CDC complement-dependent cytotoxicity -- CDR complementary determining region -- CHO Chinese hamster ovary -- EC50 half-maximal effective concentration -- Fab antigen-binding fragment -- F(ab)2 two antigen-binding fragment portions -- Fc the fragment crystallizable region -- HRP horseradish peroxidase -- IC50 half-maximal inhibitory concentration -- IdeS IgG-degrading enzyme of Streptococcus pyogenes -- Kd binding constant -- NMO neuromyelitis optica -- NMOSD neuromyelitis optica spectrum disorders -- PBS phosphate-buffered saline -- PFA paraformaldehyde -- t1/2 half time -- 2B4 isotype-matched antibody control; Neuropsychopharmacology -- Periodicals; Autonomic Agents -- Periodicals; Neuropsychopharmacologie -- Périodiques; Neuropsychopharmacology; Periodicals; Electronic journals; 615.78
• DOI: 10.1016/j.neuropharm.2019.107827
• Languages: English
• ISSNs: 0028-3908

Abstract

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 AQmab AM, bound to AQP4 in cell cultures with Kd ~ 18 ng/ml (~0.12 nM), ~8-fold greater affinity than the original antibody. AQmab AM, but without L234A/L235A Fc mutations, produced complement-dependent cytotoxicity (CDC) with EC50 ~ 82 ng/ml. AQmab AM 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 AQmab AM blocked binding of serum NMO autoantibodies to AQP4. AQmab AM 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. Highlights: Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory disease of the central nervous system. Seropositive NMOSD is caused by binding of pathogenic IgG autoantibodies to water channel aquaporin-4 on astrocytes. Aquaporumab is an engineered human monoclonal IgG antibody, with effector functions neutralized, that strongly binds to aquaporin-4. An affinity matured aquaporumab blocked NMOSD autoantibody binding to aquaporin-4 and prevented complement and cellular cytotoxicity.