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Pechlivanidou M, Xenou K, Tzanetakos D, Koutsos E, Stergiou C, Andreadou E, Voumvourakis K, Giannopoulos S, Kilidireas C, Tüzün E, Tsivgoulis G, Tzartos S, Tzartos J. Potential Role of Antibodies against Aquaporin-1 in Patients with Central Nervous System Demyelination. Int J Mol Sci 2023; 24:12982. [PMID: 37629163 PMCID: PMC10455752 DOI: 10.3390/ijms241612982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/09/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023] Open
Abstract
Aquaporins (AQPs; AQP0-AQP12) are water channels expressed in many and diverse cell types, participating in various functions of cells, tissues, and systems, including the central nervous system (CNS). AQP dysfunction and autoimmunity to AQPs are implicated in several diseases. The best-known example of autoimmunity against AQPs concerns the antibodies to AQP4 which are involved in the pathogenesis of neuromyelitis optica spectrum disorder (NMOSD), an autoimmune astrocytopathy, causing also CNS demyelination. The present review focuses on the discovery and the potential role of antibodies against AQP1 in the CNS, and their potential involvement in the pathophysiology of NMOSD. We describe (a) the several techniques developed for the detection of the AQP1-antibodies, with emphasis on methods that specifically identify antibodies targeting the extracellular domain of AQP1, i.e., those of potential pathogenic role, and (b) the available evidence supporting the pathogenic relevance of AQP1-antibodies in the NMOSD phenotype.
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Affiliation(s)
- Maria Pechlivanidou
- Tzartos NeuroDiagnostics, 11523 Athens, Greece; (M.P.); (K.X.); (E.K.); (C.S.); (S.T.)
| | - Konstantina Xenou
- Tzartos NeuroDiagnostics, 11523 Athens, Greece; (M.P.); (K.X.); (E.K.); (C.S.); (S.T.)
| | - Dimitrios Tzanetakos
- Second Department of Neurology ‘’Attikon’’ University Hospital, School of Medicine, National & Kapodistrian University of Athens, 12462 Athens, Greece; (D.T.); (K.V.); (S.G.); (G.T.)
| | - Emmanuel Koutsos
- Tzartos NeuroDiagnostics, 11523 Athens, Greece; (M.P.); (K.X.); (E.K.); (C.S.); (S.T.)
| | - Christos Stergiou
- Tzartos NeuroDiagnostics, 11523 Athens, Greece; (M.P.); (K.X.); (E.K.); (C.S.); (S.T.)
| | - Elisabeth Andreadou
- First Department of Neurology, ‘’Aiginiteion’’ University Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece; (E.A.); (C.K.)
| | - Konstantinos Voumvourakis
- Second Department of Neurology ‘’Attikon’’ University Hospital, School of Medicine, National & Kapodistrian University of Athens, 12462 Athens, Greece; (D.T.); (K.V.); (S.G.); (G.T.)
| | - Sotirios Giannopoulos
- Second Department of Neurology ‘’Attikon’’ University Hospital, School of Medicine, National & Kapodistrian University of Athens, 12462 Athens, Greece; (D.T.); (K.V.); (S.G.); (G.T.)
| | - Constantinos Kilidireas
- First Department of Neurology, ‘’Aiginiteion’’ University Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece; (E.A.); (C.K.)
- Second Department of Neurology, Henry Dunant Hospital Center, 11526 Athens, Greece
| | - Erdem Tüzün
- Department of Neuroscience, Aziz Sancar Institute of Experimental Medicine, Istanbul University, 34093 Istanbul, Turkey;
| | - Georgios Tsivgoulis
- Second Department of Neurology ‘’Attikon’’ University Hospital, School of Medicine, National & Kapodistrian University of Athens, 12462 Athens, Greece; (D.T.); (K.V.); (S.G.); (G.T.)
| | - Socrates Tzartos
- Tzartos NeuroDiagnostics, 11523 Athens, Greece; (M.P.); (K.X.); (E.K.); (C.S.); (S.T.)
- Department of Neurobiology, Hellenic Pasteur Institute, 11521 Athens, Greece
- Department of Pharmacy, University of Patras, 26504 Patras, Greece
| | - John Tzartos
- Second Department of Neurology ‘’Attikon’’ University Hospital, School of Medicine, National & Kapodistrian University of Athens, 12462 Athens, Greece; (D.T.); (K.V.); (S.G.); (G.T.)
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Hinson SR, Clift IC, Luo N, Kryzer TJ, Lennon VA. Autoantibody-induced internalization of CNS AQP4 water channel and EAAT2 glutamate transporter requires astrocytic Fc receptor. Proc Natl Acad Sci U S A 2017; 114:5491-6. [PMID: 28461494 DOI: 10.1073/pnas.1701960114] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Aquaporin-4 (AQP4) water channel-specific IgG distinguishes neuromyelitis optica (NMO) from multiple sclerosis and causes characteristic immunopathology in which central nervous system (CNS) demyelination is secondary. Early events initiating the pathophysiological outcomes of IgG binding to astrocytic AQP4 are poorly understood. CNS lesions reflect events documented in vitro following IgG interaction with AQP4: AQP4 internalization, attenuated glutamate uptake, intramyelinic edema, interleukin-6 release, complement activation, inflammatory cell recruitment, and demyelination. Here, we demonstrate that AQP4 internalization requires AQP4-bound IgG to engage an astrocytic Fcγ receptor (FcγR). IgG-lacking Fc redistributes AQP4 within the plasma membrane and induces interleukin-6 release. However, AQP4 endocytosis requires an activating FcγR's gamma subunit and involves astrocytic membrane loss of an inhibitory FcγR, CD32B. Interaction of the IgG-AQP4 complex with FcγRs triggers coendocytosis of the excitatory amino acid transporter 2 (EAAT2). Requirement of FcγR engagement for internalization of two astrocytic membrane proteins critical to CNS homeostasis identifies a complement-independent, upstream target for potential early therapeutic intervention in NMO.
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