More Efficient Complement Activation by Anti-Aquaporin-4 Compared With Anti-Myelin Oligodendrocyte Glycoprotein Antibodies

Magdalena Lerch; Kathrin Schanda; Eliott Lafon; Reinhard Würzner; Sara Mariotto; Alessandro Dinoto; Eva Maria Wendel; Christian Lechner; Harald Hegen; Kevin Rostásy; Thomas Berger; Doris Wilflingseder; Romana Höftberger; Markus Reindl

doi:10.1212/NXI.0000000000200059

More Efficient Complement Activation by Anti-Aquaporin-4 Compared With Anti-Myelin Oligodendrocyte Glycoprotein Antibodies

Neurol Neuroimmunol Neuroinflamm. 2022 Nov 22;10(1):e200059. doi: 10.1212/NXI.0000000000200059. Print 2023 Jan.

Affiliations

¹ From 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.
² From 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. [email protected].

Abstract

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 (MOGα_1-3β_1-3) 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 (MOGα_1-3β_1-3) 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.

Publication types

Comparative Study
Research Support, Non-U.S. Gov't

MeSH terms

Aquaporin 4*
Autoantibodies*
Complement Activation
Humans
Immunoglobulin G
Myelin-Oligodendrocyte Glycoprotein
Oligodendroglia

Substances

Aquaporin 4
Autoantibodies
Immunoglobulin G
Myelin-Oligodendrocyte Glycoprotein

Grants and funding

P 32699/FWF_/Austrian Science Fund FWF/Austria