Autoantibodies to synapsin I sequestrate synapsin I and alter synaptic function

Anna Rocchi, Silvio Sacchetti, Antonio De Fusco, Silvia Giovedi, Barbara Parisi, Fabrizia Cesca, Markus Höltje, Klemens Ruprecht, Gudrun Ahnert-Hilger, Fabio Benfenati

Research output: Contribution to journalArticlepeer-review

Abstract

Synapsin I is a phosphoprotein that coats the cytoplasmic side of synaptic vesicles and regulates their trafficking within nerve terminals. Autoantibodies against Syn I have been described in sera and cerebrospinal fluids of patients with numerous neurological diseases, including limbic encephalitis and clinically isolated syndrome; however, the effects and fate of autoantibodies in neurons are still unexplored. We found that in vitro exposure of primary hippocampal neurons to patient’s autoantibodies to SynI decreased the density of excitatory and inhibitory synapses and impaired both glutamatergic and GABAergic synaptic transmission. These effects were reproduced with a purified SynI antibody and completely absent in SynI knockout neurons. Autoantibodies to SynI are internalized by FcγII/III-mediated endocytosis, interact with endogenous SynI, and promote its sequestration and intracellular aggregation. Neurons exposed to human autoantibodies to SynI display a reduced density of SVs, mimicking the SynI loss-of-function phenotype. Our data indicate that autoantibodies to intracellular antigens such as SynI can reach and inactivate their targets and suggest that an antibody-mediated synaptic dysfunction may contribute to the evolution and progression of autoimmune-mediated neurological diseases positive for SynI autoantibodies.

Original languageEnglish
Article number864
JournalCell Death and Disease
Volume10
Issue number11
DOIs
Publication statusPublished - Nov 1 2019

ASJC Scopus subject areas

  • Immunology
  • Cellular and Molecular Neuroscience
  • Cell Biology
  • Cancer Research

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