GluA3 autoantibodies induce alterations in dendritic spine and behavior in mice

Area of Science:

• Neuroscience
• Immunology
• Pathology

Background:

• Autoantibodies targeting GluA3 subunits of AMPA receptors (AMPARs) are linked to Rasmussen's encephalitis, epilepsy, and cognitive deficits.
• Anti-GluA3 immunoglobulin G (IgG) has been identified in patients with frontotemporal dementia (FTD), suggesting a potential role in neurodegeneration.

Purpose of the Study:

• To investigate the in vivo behavioral, molecular, and morphological effects of anti-GluA3 IgG in a preclinical model.
• To explore the pathogenic role of anti-GluA3 IgG in the context of FTD.

Main Methods:

• Intracerebroventricular infusion of purified anti-GluA3 IgG from FTD patients or control IgG into mice.
• Biochemical analysis of synaptic GluA3-containing AMPAR levels in the prefrontal cortex and hippocampus.
• Assessment of behavioral changes including recognition memory, social behavior, and social cognition.
• Confocal imaging to evaluate dendritic spine morphology in the prefrontal cortex.

Main Results:

• Anti-GluA3 IgG reduced synaptic GluA3-containing AMPAR levels in the prefrontal cortex but not the hippocampus.
• Mice treated with anti-GluA3 IgG exhibited impaired recognition memory, social behavior, and social cognitive functions.
• Profound alterations in dendritic spine morphology were observed in the prefrontal cortex of treated animals.
• All observed alterations were transient, resolving within 10-14 days post-injection.

Conclusions:

• In vivo administration of anti-GluA3 IgG induces transient behavioral, molecular, and morphological changes in mice.
• These findings suggest a novel autoimmune mechanism involving excitatory synapses in FTD patients with anti-GluA3 IgG.
• Anti-GluA3 IgG may contribute to the clinical symptoms observed in FTD patients.