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Induction of Paralysis and Visual System Injury in Mice by T Cells Specific for Neuromyelitis Optica Autoantigen Aquaporin-4
Published on: August 21, 2017
More Efficient Complement Activation by Anti-Aquaporin-4 Compared With Anti-Myelin Oligodendrocyte Glycoprotein
Magdalena Lerch1, Kathrin Schanda1, Eliott Lafon1
1From the Clinical Department of Neurology (M.L., K.S., H.H., M.R.), Medical University of Innsbruck, Austria; Institute of Hygiene and Medical Microbiology (E.L., R.W., D.W.), Medical University of Innsbruck, Austria; Neurology Unit (S.M., A.D.), Department of Neuroscience, Biomedicine, and Movement Sciences, University of Verona, Italy; Department of Pediatric Neurology (E.M.W.), Olgahospital/Klinikum Stuttgart, Germany; Department of Pediatrics I (C.L.), Medical University of Innsbruck, Austria; Paediatric Neurology (K.R.), Witten/Herdecke University, Children's Hospital Datteln, Germany; Department of Neurology (T.B.), Medical University of Vienna, Austria; and Division of Neuropathology and Neurochemistry (C.L., R.H.), Department of Neurology, Medical University of Vienna, Austria.
Background And Objectives:
The objective was to study complement-mediated cytotoxicity induced by immunoglobulin G (IgG) anti-aquaporin-4 antibodies (AQP4-IgG) and anti-myelin oligodendrocyte glycoprotein antibodies (MOG-IgG) in human serum samples from patients suffering from the rare demyelinating diseases of the CNS neuromyelitis optica spectrum disorder (NMOSD) and MOG-IgG-associated disease (MOGAD).
Methods:
A cell-based assay with HEK293A cells expressing different MOG isoforms (MOGα1-3β1-3) or AQP4-M23 was used. Cells were incubated with human MOG-IgG or AQP4-IgG-positive serum samples together with active or heat-inactivated human complement, and complement-dependent cytotoxicity (CDC) was measured with a lactate dehydrogenase assay. To further quantify antibody-mediated cell damage, formation of the terminal complement complex (TCC) was analyzed by flow cytometry. In addition, immunocytochemistry of the TCC and complement component 3 (C3) was performed.
Results:
AQP4-IgG-positive serum samples induced higher CDC and TCC levels than MOG-IgG-positive sera. Notably, both showed a correlation between antibody titers and CDC and also between titers and TCC levels. In addition, all 6 MOG isoforms tested (MOGα1-3β1-3) could induce at least some CDC; however, the strongest MOG-IgG-induced CDC levels were found on MOGα1, MOGα3, and MOGβ1. Different MOG-IgG binding patterns regarding recognition of different MOG isoforms were investigated, and it was found that MOG-IgG recognizing all 6 isoforms again induced highest CDC levels on MOGα1 and MOGβ1. Furthermore, surface staining of TCC and C3 revealed positive staining on all 6 MOG isoforms tested, as well as on AQP4-M23.
Discussion:
Both MOG-IgG and AQP4-IgG are able to induce CDC in a titer-dependent manner. However, AQP4-IgG showed markedly higher levels of CDC compared with MOG in vitro on target cells. This further highlights the role of complement in AQP4-IgG-mediated disease and diminishes the importance of complement activation in MOG-IgG-mediated autoimmune disease.
