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Pharmacologic inhibition of 5-lipoxygenase improves memory, rescues synaptic dysfunction, and ameliorates tau pathology in a transgenic model of tauopathy.

ABSTRACT: 5-Lipoxygenase (5-LO) is a protein widely distributed in the central nervous system where it modulates amyloidosis and memory impairments in transgenic mouse models of Alzheimer's disease. However, no data are available as to whether 5-LO is elevated in human tauopathy or if it directly influences tau pathology in a relevant model of the disease.We assayed 5-LO levels in brain samples from patients with tauopathy and transgenic tau mice, and we evaluated the effect of 5-LO pharmacologic inhibition on the phenotype of these mice.The 5-LO protein is upregulated in human tauopathy and transgenic tau mice brains. Pharmacologic blockade of 5-LO in tau mice resulted in significant memory improvement, rescue of synaptic integrity and dysfunction, and reduction of tau pathology via a cdk5-dependent mechanism.These results establish a key role of 5-LO in the development of the tau pathology phenotype and demonstrate it to be a novel viable therapeutic target for the pharmacologic treatment of human tauopathy.

SUBMITTER: Giannopoulos PF

PROVIDER: S-EPMC4529386 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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Pharmacologic inhibition of 5-lipoxygenase improves memory, rescues synaptic dysfunction, and ameliorates tau pathology in a transgenic model of tauopathy.

Giannopoulos Phillip F PF Chu Jin J Sperow Margaret M Li Jian-Guo JG Yu W Haung WH Kirby Lynn G LG Abood Mary M Praticò Domenico D

Biological psychiatry 20150207 10

<h4>Background</h4>5-Lipoxygenase (5-LO) is a protein widely distributed in the central nervous system where it modulates amyloidosis and memory impairments in transgenic mouse models of Alzheimer's disease. However, no data are available as to whether 5-LO is elevated in human tauopathy or if it directly influences tau pathology in a relevant model of the disease.<h4>Methods</h4>We assayed 5-LO levels in brain samples from patients with tauopathy and transgenic tau mice, and we evaluated the ef ...[more]

PMID: 25802082

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Project description:IntroductionThe typical symptoms of Alzheimer's disease (AD) are cognitive impairment, disrupted spatial orientation, behavioral and psychiatric abnormalities, and later motor deficits. Neuropathologically, AD is characterized by deposits of pathological forms of endogenous proteins - amyloid-β, and neurofibrillary tau protein pathology. The latter closely correlates with brain atrophy and clinical impairment. Pharmacological therapies for these pathologies are largely absent, raising the question whether non-pharmacological interventions could be efficacious. Environmental factors can play a role in the manifestation of AD. It is unknown whether enriched environment (EE) can ameliorate the propagation of protein aggregates or their toxic components.MethodsWe injected insoluble tau extracts from human brains with AD (600 or 900 ng per animal) into hippocampi of SHR72 transgenic rats that express non-mutated truncated human tau 151-391/4R, but usually do not develop hippocampal tangles. The rats had either standard housing, or could access an EE 5×/week for 3 months. Behavioral analysis included the Morris Water Maze (MWM). Histological analysis was used to assess the propagation of tau pathology.ResultsAnimals exposed to EE performed better in the MWM (spatial acquisition duration and total distance, probe test); unexposed animals improved over the course of acquisition trials, but their mean performance remained below that of the EE group. Enriched environment abrogated tau propagation and hippocampal tangle formation in the 600 ng group; in the 900 ng group, tangle formation was ∼10-fold of the 600 ng group, and unaffected by EE.ConclusionEven a small difference in the amount of injected human AD tau can cause a pronounced difference in the number of resulting tangles. EE leads to a noticeably better spatial navigation performance of tau-injected animals. Furthermore, EE seems to be able to slow down tau pathology progression, indicating the possible utility of similar interventions in early stages of AD where tangle loads are still low.

Project description:Alzheimer's disease (AD), the most common tauopathy, is an age-dependent, progressive neurodegenerative disease. Epidemiological studies implicate the role of genetic background in the onset and progression of AD. Despite mutations in familial AD, several risk factors have been implicated in sporadic AD, of which the onset is unknown. In AD, there is a sequential and hierarchical spread of tau pathology to other brain areas. Studies have strived to understand the factors that influence this characteristic spread. Using transgenic rat models with different genetic backgrounds, we reported that the genetic background may influence the manifestation of neurofibrillary pathology. In this study we investigated whether genetic background has an influence in the spread of tau pathology, using hippocampal inoculations of insoluble tau from AD brains in rodent models of tauopathy with either a spontaneously hypertensive (SHR72) or Wistar-Kyoto (WKY72) genetic background. We observed that insoluble tau from human AD induced AT8-positive neurofibrillary structures in the hippocampus of both lines. However, there was no significant difference in the amount of neurofibrillary structures, but the extent of spread was prominent in the W72 line. On the other hand, we observed significantly higher levels of AT8-positive structures in the parietal and frontal cortical areas in W72 when compared to SHR72. Interestingly, we also observed that the microglia in these brain areas in W72 were predominantly phagocytic in morphology (62.4% in parietal and 47.3% in frontal), while in SHR72 the microglia were either reactive or ramified (67.2% in parietal and 84.7% in frontal). The microglia in the hippocampus and occipital cortex in both lines were reactive or ramified structures. Factors such as gender or age are not responsible for the differences observed in these animals. Put together, our results, for the first time, show that the immune response modulating genetic variability is one of the factors that influences the propagation of tau neurofibrillary pathology.

Project description:BackgroundMolecular tweezers (MTs) are broad-spectrum inhibitors of abnormal protein aggregation. A lead MT, called CLR01, has been demonstrated to inhibit the aggregation and toxicity of multiple amyloidogenic proteins in vitro and in vivo. Previously, we evaluated the effect of CLR01 in the 3 × Tg mouse model of Alzheimer's disease, which overexpresses mutant human presenilin 1, amyloid β-protein precursor, and tau and found that subcutaneous administration of the compound for 1 month led to a robust reduction of amyloid plaques, neurofibrillary tangles, and microgliosis. CLR01 also has been demonstrated to inhibit tau aggregation in vitro and tau seeding in cell culture, yet because in Alzheimer's disease (AD) and in the 3 × Tg model, tau hyperphosphorylation and aggregation are thought to be downstream of Aβ insults, the study in this model left open the question whether CLR01 affected tau in vivo directly or indirectly.MethodsTo determine if CLR01 could ameliorate tau pathology directly in vivo, we tested the compound similarly using the P301S-tau (line PS19) mouse model. Mice were administered 0.3 or 1.0 mg/kg per day CLR01 and tested for muscle strength and behavioral deficits, including anxiety- and disinhibition-like behavior. Their brains then were analyzed by immunohistochemical and biochemical assays for pathological forms of tau, neurodegeneration, and glial pathology.ResultsCLR01 treatment ameliorated muscle-strength deterioration, anxiety-, and disinhibition-like behavior. Improved phenotype was associated with decreased levels of pathologic tau forms, suggesting that CLR01 exerts a direct effect on tau in vivo. Limitations of the study included a relatively short treatment period of the mice at an age in which full pathology is not yet developed. In addition, high variability in this model lowered the statistical significance of the findings of some outcome measures.ConclusionsThe findings suggest that CLR01 is a particularly attractive candidate for the treatment of AD because it targets simultaneously the two major pathogenic proteins instigating and propagating the disease, amyloid β-protein (Aβ), and tau, respectively. In addition, our study suggests that CLR01 can be used for the treatment of other tauopathies in the absence of amyloid pathology.

Dataset Information

Pharmacologic inhibition of 5-lipoxygenase improves memory, rescues synaptic dysfunction, and ameliorates tau pathology in a transgenic model of tauopathy.

Publications

Pharmacologic inhibition of 5-lipoxygenase improves memory, rescues synaptic dysfunction, and ameliorates tau pathology in a transgenic model of tauopathy.

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