Science Daily explainer: https://www.sciencedaily.com/releases/2 ... 131220.htm
From open access paper:Researchers then tried treating APOE4 mice with an inhibitor known to suppress Cyclophilin A. The inhibitor not only improved integrity in the blood-brain barrier in APOE4 mice, but also prevented development of further neuron loss and behavioral deficits. Researchers observed that the APOE4 mice treated with the inhibitor did not exhibit behavioral deficits during daily activities. This suggests that treatment targeting this pathway might have the potential to also slow down the progression of vascular and neurodegenerative disorders in people with Alzheimer's disease who have the APOE4 gene.
"So far there has been little hope for those in the late stage of the disease, which is very hard on patients and their loved ones," said Zlokovic. "We are excited to further study the potential that interventions focused on blood-brain barrier repair and blood vessel strength, independent of amyloid pathology, could have on slowing down or stopping neurodegeneration and cognitive decline in advanced Alzheimer's disease."
The inhibitor used in this study to suppress the Cyclophilin A, Debio-025, has been used in humans to treat hepatitis C, suggesting this could be a potential treatment for cognitive impairment in APOE4 carriers that show Cyclophilin A-MMP9 pathway activity in early or late disease stages.
APOE4 accelerates advanced-stage vascular and neurodegenerative disorder in old Alzheimer’s mice via cyclophilin A independently of amyloid-β
https://www.nature.com/articles/s43587-021-00073-z
Axel Montagne, Angeliki M. Nikolakopoulou, Mikko T. Huuskonen, Abhay P. Sagare, Erica J. Lawson, Divna Lazic, Sanket V. Rege, Alexandra Grond, Edward Zuniga, Samuel R. Barnes, Jacob Prince, Meghana Sagare, Ching-Ju Hsu, Mary J. LaDu, Russell E. Jacobs & Berislav V. Zlokovic
Nature Aging volume 1, pages 506–520 (2021)
DOI: 10.1038/s43587-021-00073-z
Abstract
Apolipoprotein E4 (APOE4), the main susceptibility gene for Alzheimer’s disease (AD), leads to vascular dysfunction, amyloid-β pathology, neurodegeneration and dementia. How these different pathologies contribute to advanced-stage AD remains unclear. Using aged APOE knock-in mice crossed with 5xFAD mice, we show that, compared to APOE3, APOE4 accelerates blood–brain barrier (BBB) breakdown, loss of cerebral blood flow, neuronal loss and behavioral deficits independently of amyloid-β. BBB breakdown was associated with activation of the cyclophilin A-matrix metalloproteinase-9 BBB-degrading pathway in pericytes. Suppression of this pathway improved BBB integrity and prevented further neuronal loss and behavioral deficits in APOE4;5FAD mice while having no effect on amyloid-β pathology. Thus, APOE4 accelerates advanced-stage BBB breakdown and neurodegeneration in Alzheimer’s mice via the cyclophilin A pathway in pericytes independently of amyloid-β, which has implication for the pathogenesis and treatment of vascular and neurodegenerative disorder in AD.