Amyloid-[beta] pathology enhances pathological fibrillary tau seeding induced by Alzheimer PHF in vivo

• Published in: Acta neuropathologica Vol. 137; no. 3; p. 397
• Main Authors: Vergara, Cristina, Houben, Sarah, Suain, Valérie, Yilmaz, Zehra, De Decker, Robert, Vanden Dries, Virginie, Boom, Alain
• Format: Journal Article
• Language: English
• Published: Springer 01.03.2019
• Subjects: Advertising executives; Alzheimer's disease; Analysis; Brain; Dementia; EDTA; Genetic engineering; Neurophysiology; Parkinsonism; Physiological aspects
• ISSN: 0001-6322; 1432-0533
• DOI: 10.1007/s00401-018-1953-5

Neuropathological analysis in Alzheimer's disease (AD) and experimental evidence in transgenic models overexpressing frontotemporal dementia with Parkinsonism linked to chromosome 17 (FTDP-17) mutant tau suggest that amyloid-[beta] pathology enhances the development of tau pathology. In this work, we analyzed this interaction independently of the overexpression of an FTDP-17 mutant tau, by analyzing tau pathology in wild-type (WT), 5xFAD, APP.sup.-/- and tau.sup.-/- mice after stereotaxic injection in the somatosensory cortex of short-length native human AD-PHF. Gallyas and phosphotau-positive tau inclusions developed in WT, 5xFAD, and APP.sup.-/- but not in tau.sup.-/- mice. Ultrastructural analysis demonstrated their intracellular localization and that they were composed of straight filaments. These seeded tau inclusions were composed only of endogenous murine tau exhibiting a tau antigenic profile similar to tau aggregates in AD. Insoluble tau level was higher and ipsilateral anteroposterior and contralateral cortical spreading of tau inclusions was more important in AD-PHF-injected 5xFAD mice than in WT mice. The formation of large plaque-associated dystrophic neurites positive for oligomeric and phosphotau was observed in 5xFAD mice injected with AD-PHF but never in control-injected or in non-injected 5xFAD mice. An increased level of the p25 activator of CDK5 kinase was found in AD-PHF-injected 5xFAD mice. These data demonstrate in vivo that the presence of A[beta] pathology enhances experimentally induced tau seeding of endogenous, wild-type tau expressed at physiological level, and demonstrate the fibrillar nature of heterotopically seeded endogenous tau. These observations further support the hypothesis that A[beta] enhances tau pathology development in AD through increased pathological tau spreading.