Anti-VGLUT2 autoantibodies in neurological diseases

Area of Science:

• Neuroimmunology
• Autoimmune Diseases
• Biomarker Discovery

Background:

• Autoantibodies are crucial for diagnosing autoimmune diseases and guiding treatment.
• Uncharacterized autoantibodies persist in some neurological autoimmune disease patients.
• Identifying novel autoantibodies is key to understanding disease mechanisms.

Purpose of the Study:

• To identify the target antigen of previously uncharacterized autoantibodies found in patient sera.
• To characterize the clinical presentation and potential treatment response in patients with these novel autoantibodies.
• To establish anti-VGLUT2 autoantibodies as a distinct biomarker for specific neurological autoimmune disorders.

Main Methods:

• Indirect immunofluorescence assay (IIFA) on neuronal tissue.
• Immunoprecipitation and mass spectrometry to identify autoantibody targets.
• Recombinant IIFA, competitive inhibition assays, and colocalization studies to confirm VGLUT2 as the target.
• Immunoblotting with recombinant antigen fragments to map the epitope.

Main Results:

• Vesicular glutamate transporter 2 (VGLUT2) was identified as the autoantibody target in 285/314 patients.
• Associated diagnoses included encephalitis (25/87), dementia/cognitive impairment (17/87), and polyneuropathy (16/87).
• Index patients frequently presented with cognitive changes, sensorimotor disturbances, gait abnormalities, and visual impairments, often with coexisting chronic conditions.

Conclusions:

• Anti-VGLUT2 autoantibodies represent a newly identified biomarker for neurological autoimmune disorders.
• These disorders may manifest as encephalitis, cognitive deficits, and neuropathy.
• Immunotherapy showed beneficial effects in some patients, suggesting potential for immunomodulatory treatment.