Converging synaptic and network dysfunctions in distinct autoimmune encephalitis.

Area of Science:

• Neuroscience
• Immunology
• Molecular Biology

Background:

• Autoimmune encephalitis presents with prominent neuropsychiatric and cognitive symptoms, regardless of the targeted neurotransmitter receptor.
• The precise mechanisms driving these shared symptoms in autoimmune encephalitis are not fully understood.

Purpose of the Study:

• To investigate the impact of patient-derived monoclonal autoantibodies against N-methyl-D-aspartate receptors (NMDAR) and gamma-aminobutyric acid A receptors (GABAaR) on hippocampal network function.
• To elucidate the cellular and synaptic mechanisms underlying network dysfunction in autoimmune encephalitis.

Main Methods:

• Utilized patient-derived monoclonal autoantibodies targeting NMDAR and GABAaR.
• Examined synaptic receptor membrane dynamics, content, and transmission in the hippocampal network.
• Assessed neuronal activity, protein kinase signaling, and excitation/inhibition balance at the cellular level.

Main Results:

• Both NMDAR and GABAaR autoantibodies altered excitatory and inhibitory synaptic receptor dynamics and transmission, irrespective of antibody affinity or effect.
• These effects were dependent on neuronal activity and involved protein kinase signaling.
• Both autoantibodies increased the excitation/inhibition balance and led to hippocampal network hyperactivation via distinct cellular alterations.

Conclusions:

• Autoantibodies targeting distinct neurotransmitter receptors (NMDAR and GABAaR) can converge to cause network dysfunction in the brain.
• Shared and distinct mechanisms contribute to the observed network hyperactivation and excitation/inhibition imbalance in autoimmune encephalitis.
• These findings provide insights into the pathophysiology of autoimmune encephalitis and its associated neurological and psychiatric symptoms.