Dataset Information

Intravenous Injection of PHF-Tau Proteins From Alzheimer Brain Exacerbates Neuroinflammation, Amyloid Beta, and Tau Pathologies in 5XFAD Transgenic Mice.

ABSTRACT: Alzheimer's disease (AD) is characterized by the accumulation in the brain of intraneuronal aggregates of abnormally and hyperphosphorylated tau proteins and of extracellular deposits of amyloid-? surrounded by dystrophic neurites. Numerous experimental models have shown that tau pathology develops in the brain after intracerebral injection of brain homogenates or pathological tau [paired helical filaments (PHF)-tau)] from AD brains. Further investigations are however necessary to identify or exclude potential extracerebral routes of tau pathology transmission, e.g., through the intravascular route. In this study, we have analyzed the effect of intravenous injection of PHF-tau proteins from AD brains on the formation of tau and amyloid pathologies in the brain of wild-type (WT) mice and of 5XFAD mice (an amyloid model). We observed that 5XFAD mice with a disrupted blood-brain barrier showed increased plaque-associated astrogliosis, microgliosis, and increased deposits of A?40 and A?42 after intravenous injection of PHF-tau proteins. In addition, an increased phosphotau immunoreactivity was observed in plaque-associated dystrophic neurites. These results suggest that blood products contaminated by PHF-tau proteins could potentially induce an exacerbation of neuroinflammation and AD pathologies.

SUBMITTER: Houben S

PROVIDER: S-EPMC7381181 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Intravenous Injection of PHF-Tau Proteins From Alzheimer Brain Exacerbates Neuroinflammation, Amyloid Beta, and Tau Pathologies in 5XFAD Transgenic Mice.

Houben Sarah S de Fisenne Marie-Ange MA Ando Kunie K Vanden Dries Virginie V Poncelet Luc L Yilmaz Zehra Z Mansour Salwa S De Decker Robert R Brion Jean-Pierre JP Leroy Karelle K

Frontiers in molecular neuroscience 20200714

Alzheimer's disease (AD) is characterized by the accumulation in the brain of intraneuronal aggregates of abnormally and hyperphosphorylated tau proteins and of extracellular deposits of amyloid-β surrounded by dystrophic neurites. Numerous experimental models have shown that tau pathology develops in the brain after intracerebral injection of brain homogenates or pathological tau [paired helical filaments (PHF)-tau)] from AD brains. Further investigations are however necessary to identify or ex ...[more]

PMID: 32765217

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Project description:Frontotemporal lobar degeneration with ? pathology (FTLD-tau) is one of a group of neurodegenerative diseases that manifests with cognitive decline. Alzheimer (AD) and cerebrovascular lesions are commonly noted in the brains of most elderly individuals, begging the question as to whether (a) coexisting AD and vascular pathology or age contribute to the development of FTLD-tau disorders and vice versa and (b) FTLD-tau-like pathology can be found in non-diseased individuals. We studied brains of FTLD-tau cases exhibiting (a) argyrophilc grain disease (AGD), (b) progressive supranuclear palsy (PSP), (c) corticobasal degeneration (CBD), or (d) Pick's disease (PiD) for coexisting AD and vascular pathology for comparison with that of non-diseased individuals and AD patients. We confirmed that AGD lowered the threshold for AD pathology to cause dementia. Such an effect was not seen in PSP, CBD, or PiD. In PiD, white matter degeneration and demyelination was observed in the frontal and temporal lobes in association with small vessel disease (SVD)-related changes in white matter arteries. Age at death varied among the four types of FTLD-tau. PiD cases were youngest at death followed by CBD, PSP, and finally AGD. In 9.8% of non-diseased controls, we found grains, coiled bodies, and/or ?-positive astrocytes mimicking an AGD-like pattern. Moreover, the prevalence of FTLD-tau pathology in non-diseased individuals increased with age. In summary, this study demonstrates that age impacts of the diversity of neuropathological changes in FTLD-tau. The age-related coexistence of AD-related pathology is, thereby, associated with AGD but not with PSP, CBD, and PiD. Moreover, severe SVD and white matter demyelination is associated with PiD indicating a role of vascular copathology in this type of FTLD-tau. Finally, our finding that FTLD-tau-related pathological lesions occur in non-diseased individuals suggests that preclinical stages of FTLD-tau exist. As such, our results indicate that age, together with vascular and AD-related copathology, contributes to the morphological appearance of FTLD-tau.

Project description:Short peptide sequences within the microtubule binding domain of the protein Tau are proposed to be core nucleation sites for formation of amyloid fibrils displaying the paired helical filament (PHF) morphology characteristic of neurofibrillary tangles. To study the structure of these proposed nucleation sites, we analyzed the x-ray diffraction patterns from the assemblies formed by a variety of PHF/tau-related peptide constructs containing the motifs VQIINK (PHF6*) in the second repeat and VQIVYK (PHF6) in the third repeat of tau. Peptides included: tripeptide acetyl-VYK-amide (AcVYK), tetrapeptide acetyl-IVYK-amide (AcPHF4), hexapeptide acetyl-VQIVYK-amide (AcPHF6), and acetyl-GKVQIINKLDLSNVQKDNIKHGSVQIVYKPVDLSKVT-amide (AcTR4). All diffraction patterns showed reflections at spacings of 4.7 A, 3.8 A, and approximately 8-10 A, which are characteristic of an orthogonal unit cell of beta-sheets having dimensions a=9.4 A, b=6.6 A, and c=approximately 8-10 A (where a, b, and c are the lattice constants in the H-bonding, chain, and intersheet directions). The sharp 4.7 A reflections indicate that the beta-crystallites are likely to be elongated along the H-bonding direction and in a cross-beta conformation. The assembly of the AcTR4 peptide, which contains both the PHF6 and PHF6* motifs, consisted of twisted sheets, as indicated by a unique fanning of the diffuse equatorial scattering and meridional accentuation of the (210) reflection at 3.8 A spacing. The diffraction data for AcVYK, AcPHF4, and AcPHF6 all were consistent with approximately 50 A-wide tubular assemblies having double-walls, where beta-strands constitute the walls. In this structure, the peptides are H-bonded together in the fiber direction, and the intersheet direction is radial. The positive-charged lysine residues face the aqueous medium, and tyrosine-tyrosine aromatic interactions stabilize the intersheet (double-wall) layers. This particular contact, which may be involved in PHF fibril formation, is proposed here as a possible aromatic target for anti-tauopathy drugs.

Dataset Information

Intravenous Injection of PHF-Tau Proteins From Alzheimer Brain Exacerbates Neuroinflammation, Amyloid Beta, and Tau Pathologies in 5XFAD Transgenic Mice.

Publications

Intravenous Injection of PHF-Tau Proteins From Alzheimer Brain Exacerbates Neuroinflammation, Amyloid Beta, and Tau Pathologies in 5XFAD Transgenic Mice.

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