Abstract
Background
Accurate placement of the macaque within the Alzheimer's disease (AD) research framework is essential to discover early-stage predictive biomarkers.
Objective
To assess utility of the aging macaque in advancing translational biomarker development for preclinical AD, we evaluated relative signal strength of comparable neuropathologic phenomena in macaques and patients.
Methods
We compared pathology in patient and macaque formalin-fixed paraffin embedded (FFPE) tissues using identical criteria. We quantified expression of amyloid-β (Aβ), pTau, and inflammatory and senescence markers across species. Distribution of AD-relevant markers were compared in FFPE and perfused frozen macaque brain to assess expression of labile proteins that could inform in-life fluid biomarkers.
Results
Aβ pathology in macaques closely approximated patient pathology. Complex plaque composition in macaques implied significant disruption of synaptic connectivity. In FFPE tissue, pretangle pTau immunoreactivity placed the macaque in Braak Stage 1b. In perfused frozen tissue, soluble pTau distribution approximated Braak Stage III-IV. In macaque, Aβ, pTau, and acetylcholinesterase labeling co-localized to AD-vulnerable circuits. Significant association of glial fibrillary acidic protein with Aβ occurred in humans only. The senescence marker p16 correlated positively with pTau expression and negatively with Aβ in patients only. Macaques lacked neuropathologic co-morbidities.
Conclusions
AD-relevant neuropathologic signals in the macaque support biomarker discovery in the areas of Aβ plaque evolution and associated synaptic disruption as well as early-stage tau phosphorylation. Relative protection from accumulation of senescence markers, fibrillar tau and neuropathologic co-morbidities in macaque implicate species difference in rates of biological brain aging. We provide over 4000 digital slides for further study.
Keywords
Get full access to this article
View all access options for this article.
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
