APOE4 accelerates advanced-stage vascular and neurodegenerative disorder in old Alzheimer's mice via cyclophilin A independently of amyloid-β.
Level 5 - mechanism / opinion, no new human data
Preclinical animal model research
PubMed 35291561 · doi:10.1038/s43587-021-00073-z
What was done
Researchers investigated the mechanisms linking APOE4 to advanced-stage Alzheimer's disease pathology using aged APOE knock-in mice crossed with 5xFAD transgenic mice. They compared APOE4-expressing mice to APOE3 controls, evaluating blood-brain barrier (BBB) integrity, cerebral blood flow, neuronal loss, behavioral performance, and the involvement of the cyclophilin A-matrix metalloproteinase-9 (MMP-9) pathway in pericytes, including the effect of suppressing this pathway.
What was found
The abstract reports no numerical values or confidence intervals. Compared to APOE3, APOE4 accelerated BBB breakdown, reduced cerebral blood flow, and exacerbated neuronal loss and behavioral deficits independently of amyloid-β load. Mechanistically, BBB breakdown was associated with activation of the cyclophilin A-MMP9 pathway in pericytes; suppressing this pathway restored BBB integrity and prevented additional neuronal loss and behavioral deficits in APOE4;5xFAD mice without altering amyloid-β pathology.
Why it matters
This study highlights a pericyte-driven, amyloid-independent vascular pathway through which APOE4 contributes to neurodegeneration, suggesting cyclophilin A signaling as a potential therapeutic target in APOE4-associated dementia.
Limits
The study was conducted entirely in transgenic mouse models, which do not fully capture the complexity of human Alzheimer's disease. The abstract does not report sample sizes, exact mouse ages, quantitative effect sizes, or specific intervention details.
Cited by
- supports Administering the cyclophilin A inhibitor Debio 025 daily for one month to humanized APOE4 mice partially restored vascular tight junctions, pericyte coverage, and improved neuronal function and cognition.