Patient-Derived Anti-NMDAR Antibody Disinhibits Cortical Neuronal Networks through Dysfunction of Inhibitory Neuron...

Area of Science:

• Neuroscience
• Immunology
• Pathophysiology

Background:

• Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a severe neuropsychiatric disorder.
• Autoantibodies against NMDARs cause diverse symptoms, including psychiatric manifestations, cognitive impairment, seizures, and autonomic instability.
• Previous research primarily focused on hippocampal effects, leaving cortical network dysfunction under-explored.

Purpose of the Study:

• To investigate the effects of patient-derived anti-NMDAR autoantibodies on cortical network function.
• To elucidate the specific mechanisms by which these antibodies induce cortical hyperexcitability.
• To explore potential links between cortical NMDAR antibody effects and other neuropsychiatric disorders.

Main Methods:

• Utilized a patient-derived monoclonal antibody targeting the NR1 subunit of NMDAR.
• Applied in vitro imaging and electrophysiological techniques on rodent cortical neuron cultures.
• Assessed effects on network activity, Npas4 signaling, synaptic transmission, and neuronal currents.

Main Results:

• The hNR1 antibody induced a hyperexcitable state in cortical networks.
• Disruption of network stabilizing mechanisms, including Npas4 signaling, was observed.
• Reduced synaptic output from inhibitory neurons led to decreased inhibitory drive and presynaptic protein levels.
• Single-cell analysis revealed selective impairment of NMDAR currents and synaptic transmission in cortical inhibitory neurons, but not excitatory neurons.

Conclusions:

• A novel, cortex-specific mechanism of antibody-induced neuronal hyperexcitability was identified.
• The findings highlight brain regional specificity in the pathology of autoimmune encephalitis.
• Impaired inhibitory neuron function leading to cortical disinhibition may share mechanisms with disorders like schizophrenia.