Microglia and complement mediate early corticostriatal synapse loss and cognitive dysfunction in Huntington's disease

Area of Science:

• Neuroscience
• Immunology
• Genetics

Background:

• Huntington's disease (HD) is a genetic neurodegenerative disorder with early basal ganglia pathology.
• Mechanisms of region-specific degeneration and early cognitive deficits in HD remain unclear.

Purpose of the Study:

• Investigate the role of innate immune molecules in selective corticostriatal synapse loss in HD.
• Determine if complement cascade activation contributes to early cognitive phenotypes in HD.

Main Methods:

• Analysis of postmortem HD brain tissue and cerebrospinal fluid.
• Preclinical studies in genetic HD models using complement inhibition (antibody therapy, genetic ablation).
• Assessment of synaptic integrity, microglial activity, and cognitive function.

Main Results:

• Selective loss of corticostriatal synapses in HD patients, linked to activated complement proteins.
• Elevated complement levels in premanifest HD patients' CSF correlate with disease burden.
• Complement-mediated elimination of synapses by microglia in HD models, requiring mutant huntingtin expression.
• Inhibition of complement cascade prevented synapse loss and rescued cognitive deficits in HD models.

Conclusions:

• Microglia and the complement cascade are implicated in early corticostriatal synapse degeneration in HD.
• Complement activation contributes to cognitive deficits in presymptomatic HD.
• Complement represents a potential therapeutic target for early intervention in Huntington's disease.