Dataset Information

ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy.

ABSTRACT: APOE4 is the strongest genetic risk factor for late-onset Alzheimer disease. ApoE4 increases brain amyloid-? pathology relative to other ApoE isoforms. However, whether APOE independently influences tau pathology, the other major proteinopathy of Alzheimer disease and other tauopathies, or tau-mediated neurodegeneration, is not clear. By generating P301S tau transgenic mice on either a human ApoE knock-in (KI) or ApoE knockout (KO) background, here we show that P301S/E4 mice have significantly higher tau levels in the brain and a greater extent of somatodendritic tau redistribution by three months of age compared with P301S/E2, P301S/E3, and P301S/EKO mice. By nine months of age, P301S mice with different ApoE genotypes display distinct phosphorylated tau protein (p-tau) staining patterns. P301S/E4 mice develop markedly more brain atrophy and neuroinflammation than P301S/E2 and P301S/E3 mice, whereas P301S/EKO mice are largely protected from these changes. In vitro, E4-expressing microglia exhibit higher innate immune reactivity after lipopolysaccharide treatment. Co-culturing P301S tau-expressing neurons with E4-expressing mixed glia results in a significantly higher level of tumour-necrosis factor-? (TNF-?) secretion and markedly reduced neuronal viability compared with neuron/E2 and neuron/E3 co-cultures. Neurons co-cultured with EKO glia showed the greatest viability with the lowest level of secreted TNF-?. Treatment of P301S neurons with recombinant ApoE (E2, E3, E4) also leads to some neuronal damage and death compared with the absence of ApoE, with ApoE4 exacerbating the effect. In individuals with a sporadic primary tauopathy, the presence of an ?4 allele is associated with more severe regional neurodegeneration. In individuals who are positive for amyloid-? pathology with symptomatic Alzheimer disease who usually have tau pathology, ?4-carriers demonstrate greater rates of disease progression. Our results demonstrate that ApoE affects tau pathogenesis, neuroinflammation, and tau-mediated neurodegeneration independently of amyloid-? pathology. ApoE4 exerts a 'toxic' gain of function whereas the absence of ApoE is protective.

SUBMITTER: Shi Y

PROVIDER: S-EPMC5641217 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy.

Shi Yang Y Yamada Kaoru K Liddelow Shane Antony SA Smith Scott T ST Zhao Lingzhi L Luo Wenjie W Tsai Richard M RM Spina Salvatore S Grinberg Lea T LT Rojas Julio C JC Gallardo Gilbert G Wang Kairuo K Roh Joseph J Robinson Grace G Finn Mary Beth MB Jiang Hong H Sullivan Patrick M PM Baufeld Caroline C Wood Michael W MW Sutphen Courtney C McCue Lena L Xiong Chengjie C Del-Aguila Jorge L JL Morris John C JC Cruchaga Carlos C Fagan Anne M AM Miller Bruce L BL Boxer Adam L AL Seeley William W WW Butovsky Oleg O Barres Ben A BA Paul Steven M SM Holtzman David M DM

Nature 20170920 7673

APOE4 is the strongest genetic risk factor for late-onset Alzheimer disease. ApoE4 increases brain amyloid-β pathology relative to other ApoE isoforms. However, whether APOE independently influences tau pathology, the other major proteinopathy of Alzheimer disease and other tauopathies, or tau-mediated neurodegeneration, is not clear. By generating P301S tau transgenic mice on either a human ApoE knock-in (KI) or ApoE knockout (KO) background, here we show that P301S/E4 mice have significantly h ...[more]

PMID: 28959956

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Project description:Inflammation is considered a mechanistic driver of Alzheimer's disease, thought to increase tau phosphorylation, the first step to the formation of neurofibrillary tangles (NFTs). To further understand how inflammation impacts the development of tau pathology, we used (hTau) mice, which express all six, non-mutated, human tau isoforms, but with an altered ratio of tau isoforms favoring 3R tau due to the concomitant loss of murine tau (mTau) that is predominantly 4R. Such an imbalance pattern has been related to susceptibility to NFTs formation, but whether or not this also affects susceptibility to systemic inflammation and related changes in tau phosphorylation is not known. To reduce the predominance of 3R tau by increasing 4R tau availability, we bred hTau mice on a heterozygous mTau background and compared the impact of systemic inflammation induced by lipopolysaccharide (LPS) in hTau mice hetero- or homozygous mTau knockout. Three-month-old male wild-type (Wt), mTau+/-, mTau-/-, hTau/mTau+/-, and hTau/mTau-/- mice were administered 100, 250, or 330 μg/kg of LPS or its vehicle phosphate buffer saline (PBS) [intravenously (i.v.), n = 8-9/group]. Sickness behavior, reflected by behavioral suppression in the spontaneous alternation task, hippocampal tau phosphorylation, measured by western immunoblotting, and circulating cytokine levels were quantified 4 h after LPS administration. The persistence of the LPS effects (250 μg/kg) on these measures, and food burrowing behavior, was assessed at 24 h post-inoculation in Wt, mTau+/-, and hTau/mTau+/- mice (n = 9-10/group). In the absence of immune stimulation, increasing 4R tau levels in hTau/mTau+/- exacerbated pS202 and pS396/404 tau phosphorylation, without altering total tau levels or worsening early behavioral perturbations characteristic of hTau/mTau-/- mice. We also show for the first time that modulating 4R tau levels in hTau mice affects the response to systemic inflammation. Behavior was suppressed in all genotypes 4 h following LPS administration, but hTau/mTau+/- exhibited more severe sickness behavior at the 100 μg/kg dose and a milder behavioral and cytokine response than hTau/mTau-/- mice at the 330 μg/kg dose. All LPS doses decreased tau phosphorylation at both epitopes in hTau/mTau+/- mice, but pS202 levels were selectively reduced at the 100 μg/kg dose in hTau/mTau-/- mice. Behavioral suppression and decreased tau phosphorylation persisted at 24 h following LPS administration in hTau/mTau+/- mice.

Dataset Information

ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy.

Publications

ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy.

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