title: A small-molecule screen yields idiotype-specific blockers of neuromyelitis optica immunoglobulin G binding to aquaporin-4.
abstract: Neuromyelitis optica (NMO) is an inflammatory demyelinating disease of the central nervous system caused by binding of anti-aquaporin-4 (AQP4) autoantibodies (NMO-IgG) to AQP4 on astrocytes. A screen was developed to identify inhibitors of NMO-IgG-dependent, complement-dependent cytotoxicity. Screening of 50,000 synthetic small molecules was done using CHO cells expressing human AQP4 and a human NMO recombinant monoclonal antibody (rAb-53). The screen yielded pyrano[2,3-c]pyrazoles that blocked rAb-53 binding to AQP4 and prevented cytotoxicity in cell culture and spinal cord slice models of NMO. Structure-activity analysis of 82 analogs yielded a blocker with IC(50) ∼ 6 μm. Analysis of the blocker mechanism indicated idiotype specificity, as (i) pyrano[2,3-c]pyrazoles did not prevent AQP4 binding or cytotoxicity of other NMO-IgGs, and (ii) surface plasmon resonance showed specific rAb-53 binding. Antibody structure modeling and docking suggested a putative binding site near the complementarity-determining regions. Small molecules with idiotype-specific antibody targeting may be useful as research tools and therapeutics.
authors.affiliation: Department of Medicine, University of California, San Francisco, California 94143-0521, USA.
authors.forename: Puay-Wah
authors.initials: PW
authors.lastname: Phuan
authors.forename: Marc O
authors.initials: MO
authors.lastname: Anderson
authors.forename: Lukmanee
authors.initials: L
authors.lastname: Tradtrantip
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.forename: Joseph
authors.initials: J
authors.lastname: Tan
authors.forename: Chiwah
authors.initials: C
authors.lastname: Lam
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Bennett
authors.forename: A S
authors.initials: AS
authors.lastname: Verkman
mesh_terms: D000818:Animals; D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects; D051401:Aquaporin 4 / Q000276:immunology* / Q000378:metabolism; D001323:Autoantibodies / Q000276:immunology / Q000378:metabolism*; D001665:Binding Sites; D016466:CHO Cells; D006224:Cricetinae; D057166:High-Throughput Screening Assays; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology / Q000378:metabolism*; D007130:Immunoglobulin Idiotypes / Q000276:immunology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D062105:Molecular Docking Simulation; D009471:Neuromyelitis Optica / Q000276:immunology* / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D011714:Pyrans / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D013116:Spinal Cord / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D013329:Structure-Activity Relationship; D020349:Surface Plasmon Resonance; D046509:Tissue Culture Techniques
chemical_list: C496030:AQP4 protein, human; D051401:Aquaporin 4; D001323:Autoantibodies; D007074:Immunoglobulin G; D007130:Immunoglobulin Idiotypes; D011714:Pyrans; D011720:Pyrazoles