Elevated Apolipoprotein E Expression in Hippocampal Microglia Drives Temporal Lobe Epilepsy Progression

Area of Science:

• Neuroscience
• Immunology
• Metabolomics

Background:

• Temporal lobe epilepsy (TLE) is the most common epilepsy type, often involving hippocampal sclerosis (HS).
• Microglia reactivity is key in TLE pathogenesis, with apolipoprotein E (APOE) potentially mediating these effects.
• The precise role of APOE in TLE progression and hippocampal microglia remains unclear.

Purpose of the Study:

• To elucidate the role of APOE and hippocampal microglia in TLE mechanisms.
• To validate APOE as a potential biomarker and therapeutic target for TLE.

Main Methods:

• Bioinformatics analysis of patient and mouse model data.
• Single-cell RNA sequencing to identify APOE-expressing microglia.
• In vitro and in vivo functional experiments in TLE mouse models.
• Genetic knockout of APOE in TLE models.

Main Results:

• APOE expression is significantly elevated in TLE-HS hippocampi and mouse models.
• A subset of microglia highly expresses APOE, increasing during disease progression.
• APOE-expressing microglia promote neuroinflammation, neuronal apoptosis, and excitability, altering glycerophospholipid metabolism.
• APOE knockout reduces gliosis, neuronal death, and seizures in TLE mice.

Conclusions:

• APOE-expressing microglia are critical drivers of hippocampal sclerosis and TLE progression.
• APOE and its downstream pathways represent promising therapeutic targets for TLE.