ALS-causing SOD1 mutants generate vascular changes prior to motor neuron degeneration

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease.
• Mutations in superoxide dismutase 1 (SOD1) are linked to familial ALS.
• The role of the blood-spinal cord barrier in ALS pathogenesis is not fully understood.

Purpose of the Study:

• To investigate the impact of ALS-linked SOD1 mutants on the blood-spinal cord barrier.
• To determine the sequence of events in SOD1-related ALS pathogenesis.

Main Methods:

• Utilized mouse models expressing SOD1 mutants with varying biochemical properties.
• Assessed blood-spinal cord barrier integrity by measuring tight junction protein levels (ZO-1, occludin, claudin-5).
• Monitored microcirculation, hypoperfusion, microhemorrhages, and neuroinflammation.

Main Results:

• SOD1 mutants disrupted the blood-spinal cord barrier by reducing tight junction proteins.
• This disruption led to microhemorrhages, release of neurotoxic products, and impaired microcirculation.
• Endothelial damage preceded motor neuron degeneration and neuroinflammation, suggesting a primary role.

Conclusions:

• ALS-linked SOD1 mutants directly damage endothelial cells, compromising the blood-spinal cord barrier.
• This early endothelial dysfunction is a key initiating event in SOD1-related ALS.
• Targeting endothelial damage may offer a therapeutic strategy for ALS.