A001 - an extracellular loop C peptide-specific AQP4 monoclonal antibody, was created by using transfected lentivirus in HEK293 cells.

A001 demonstrates the competitive and blocking advantage over NMO-IgG in vitro.

A001 can repress the complement-dependent cytotoxicity via NMO-IgG.

A001 alleviates disease severity and reduces pathological inflammation and demyelination in experimental NMO mice.

Neuromyelitis optica spectrum disorder (NMOSD) is a neuroinflammatory disease caused by an autoantibody that targets the extracellular domain (ECD) of the astrocytic water channel aquaporin-4 (AQP4-IgG or NMO-IgG). The generation of AQP4-IgG leads to the loss of AQP4 function, destruction of astrocytes via complement-dependent cytotoxicity (CDC), antibody-dependent cell-mediated cytotoxicity, and subsequent inflammatory nerve damage. Therefore, preventing NMO-IgG–AQP4 binding may represent a feasible therapeutic strategy for NMOSD. In this study, we generated a monoclonal antibody targeting the AQP4 ECD loop C (named A001). We examined its binding affinity for AQP4 and its ability to prevent NMO-IgG from binding to AQP4, inhibit CDC in culture, and mitigate NMO-like pathology in a mouse model. Fluorophore-tagged A001 displayed a staining pattern in AQP4-overexpressing HEK293 cells that overlapped the staining pattern of fluorophore-tagged NMO-IgG. Preincubation or coincubation with A001 effectively blocked NMO-IgG immunostaining. Furthermore, A001 inhibited NMO-IgG–induced damage to AQP4-overexpressing HEK293 cells in the presence of human or mouse complement. Intrathecal A001 injection also reduced demyelination and immunocyte infiltration in the optic nerve and spinal cord in an NMO-IgG–induced mouse model of NMOSD. Competitive blockade of autoantibody binding to APQ4 using an ECD peptide-specific antibody is a potentially promising therapeutic strategy for NMOSD.

AQP4

Monoclonal antibody

Complement-dependent cytotoxicity

Extracellular domain

Experimental neuromyelitis optica

© 2025 The Authors. Published by Elsevier B.V.