Cellular Uptake of α-Synuclein Oligomer-Selective Antibodies is Enhanced by the Extracellular Presence of α-Synuclein and Mediated via Fcγ Receptors
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Immunotherapy targeting aggregated α-synuclein has emerged as a potential treatment strategy against Parkinson’s disease and other α-synucleinopathies. We have developed α-synuclein oligomer/protofibril selective antibodies that reduce toxic α-synuclein in a human cell line and, upon intraperitoneal administration, in spinal cord of transgenic mice. Here, we investigated under which conditions and by which mechanisms such antibodies can be internalized by cells. For this purpose, human neuroglioma H4 cells were treated with either monoclonal oligomer/protofibril selective α-synuclein antibodies, linear epitope monoclonal α-synuclein antibodies, or with a control antibody. The oligomer/protofibril selective antibody mAb47 displayed the highest cellular uptake and was therefore chosen for additional analyses. Next, α-synuclein overexpressing cells were incubated with mAb47, which resulted in increased antibody internalization as compared to non-transfected cells. Similarly, regular cells exposed to mAb47 together with media containing α-synuclein displayed a higher uptake as compared to cells incubated with regular media. Finally, different Fcγ receptors were targeted and we then found that blockage of FcγRI and FcγRIIB/C resulted in reduced antibody internalization. Our data thus indicate that the robust uptake of the oligomer/protofibril selective antibody mAb47 by human CNS-derived cells is enhanced by extracellular α-synuclein and mediated via Fcγ receptors. Altogether, our finding lend further support to the belief that α-synuclein pathology can be modified by monoclonal antibodies and that these can target toxic α-synuclein species in the extracellular milieu. In the context of immunotherapy, antibody binding of α-synuclein would then not only block further aggregation but also mediate internalization and subsequent degradation of antigen–antibody complexes.
Keywordsα-Synuclein Parkinson’s disease Lewy bodies Monoclonal antibodies Antibody uptake Fc gamma receptors
The work was supported financially by grants from Swedish Research Council (2011-4519, 2012-2172, 2010-6745), Marianne and Marcus Wallenberg Foundation, Uppsala Berzelii Technology Center for Neurodiagnostics, Swedish Brain Foundation, Parkinson Research Foundation, Swedish Alzheimer Foundation, Swedish Parkinson Foundation, Swedish Society of Medicine, Hans-Gabriel and Alice Trolle Wachtmeister’s Foundation for Medical Research, Lundbeck Foundation, Lennart and Christina Kalén, Stohne’s Foundation, Söderström–Königska Foundation, Swedish Dementia Foundation, Björklund’s Foundation for ALS research, Magnus Bergwall Foundation, Thore Nilsson Foundation, Old Servants’ Foundation, Åhlén Foundation, Loo and Hans Osterman’s Foundation, Jeansson’s Foundation, Larsson-Röst’s Foundation, Anna Maria Lundin Foundation, Golje’s Foundation, King Gustaf V:s and Queen Victoria’s Freemason Foundation, and Göransson Sandviken’s Foundation. TLF is supported by Fundação para a Ciência e Tecnologia (SFRH/BD/74881/2010). TFO is supported by the DFG Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB).
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Conflict of interest
I have read the journal’s policy and have the following conflicts: FE and CM are employed by BioArctic Neuroscience AB. LL is co-founder of BioArctic Neuroscience AB and stock owner. This does not alter the adherence to all the CEMN policies on sharing data and materials. None of the authors have any financial relationship with the organizations that sponsored the research.
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