Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.937
Filtrar
1.
Neurology ; 95(19): e2666-e2674, 2020 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-32913022

RESUMO

BACKGROUND: Several neurotransmitter receptors activate signaling pathways that alter processing of the amyloid precursor protein (APP) into ß-amyloid (Aß). Serotonin signaling through a subset of serotonin receptors suppresses Aß generation. We proposed that escitalopram, the most specific selective serotonin reuptake inhibitor (SSRI) that inhibits the serotonin transporter SERT, would suppress Aß levels in mice. OBJECTIVES: We hypothesized that acute treatment with escitalopram would reduce Aß generation, which would be reflected chronically with a significant reduction in Aß plaque load. METHODS: We performed in vivo microdialysis and in vivo 2-photon imaging to assess changes in brain interstitial fluid (ISF) Aß and Aß plaque size over time, respectively, in the APP/presenilin 1 mouse model of Alzheimer disease treated with vehicle or escitalopram. We also chronically treated mice with escitalopram to determine the effect on plaques histologically. RESULTS: Escitalopram acutely reduced ISF Aß by 25% by increasing α-secretase cleavage of APP. Chronic administration of escitalopram significantly reduced plaque load by 28% and 34% at 2.5 and 5 mg/d, respectively. Escitalopram at 5 mg/kg did not remove existing plaques, but completely arrested individual plaque growth over time. CONCLUSIONS: Escitalopram significantly reduced Aß in mice, similar to previous findings in humans treated with acute dosing of an SSRI.


Assuntos
Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Citalopram/farmacologia , Fragmentos de Peptídeos/efeitos dos fármacos , Placa Amiloide/patologia , Inibidores de Captação de Serotonina/farmacologia , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Modelos Animais de Doenças , Líquido Extracelular , Microscopia Intravital , Camundongos , Microdiálise , Microscopia de Fluorescência por Excitação Multifotônica , Fragmentos de Peptídeos/metabolismo , Placa Amiloide/metabolismo , Presenilina-1/genética
2.
Nat Commun ; 11(1): 4727, 2020 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-32948752

RESUMO

The apolipoprotein E (APOE) gene contains both the major common risk variant for late onset Alzheimer's disease (AD), e4, and the major neuroprotective variant, e2. Here we examine the association of APOE e2 with multiple neurodegenerative pathologies, leveraging the NACC v. 10 database of 1557 brains that included 130 e2 carriers and 679 e4 carriers in order to examine potential neuroprotective effects. For AD-related pathologies of amyloid plaques and Braak stage, e2 had large and highly significant protective effects contrasted with e3/e3 and e4 carriers with odds ratios of about 0.50 for e3 contrasts and 0.10 for e4 contrasts. When we separately examined e2/e4 carriers, risk for AD pathologies was similar to that of e4 carriers, not e2 carriers. For multiple fronto-temporal lobar pathologies and tauopathies, e2 was not significantly associated with pathology. In sum, we found that e2 was associated with large but circumscribed protective effects.


Assuntos
Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Apolipoproteína E2/genética , Apolipoproteína E2/metabolismo , Genótipo , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/patologia , Apolipoproteína E4/genética , Apolipoproteína E4/metabolismo , Apolipoproteínas E/genética , Apolipoproteínas E/metabolismo , Encéfalo/metabolismo , Feminino , Degeneração Lobar Frontotemporal/metabolismo , Humanos , Modelos Logísticos , Masculino , Placa Amiloide/patologia , Tauopatias/metabolismo , alfa-Sinucleína/metabolismo
3.
Neurology ; 95(12): e1640-e1649, 2020 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-32759190

RESUMO

OBJECTIVE: To examine whether neuropathologic burden is associated with hearing impairment. METHODS: We studied 2,755 autopsied participants ≥55 years of age from the National Alzheimer's Coordinating Center database. Participants had at least 1 clinical evaluation at US National Institute on Aging-funded Alzheimer's Disease Center no more than 2 years before death. Patients were classified as hearing impaired by clinician report at baseline. Common dementia neuropathologies included Alzheimer disease pathologic change (Consortium to Establish a Registry for Alzheimer's Disease neuritic plaque density, neurofibrillary degeneration Braak stage), Lewy body disease, gross infarcts, and microinfarcts. Logistic regression models predicted impaired hearing with adjustment for age at death, sex, race, education, center, and follow-up time. Relative risks were calculated with the use of marginal standardization. RESULTS: Impaired hearing was common (32%). In participants who were cognitively normal at baseline (n = 580), impaired hearing was associated with higher Braak stage (relative risk [RR] 1.33 per 2-stage increase, 95% confidence interval [CI] 1.06-1.66) but not other pathologies. In participants with dementia (n = 2,175), impaired hearing was positively associated with microinfarcts (RR 1.18, 95% CI 1.00-1.39) and inversely associated with neuritic plaque density (RR 0.91 per score increase, 95% CI 0.85-0.99). Development of impaired hearing in those with cognitive impairment was associated with neocortical Lewy bodies (1.26, 95% CI 1.02-1.55). CONCLUSIONS: Impaired hearing, reported before the onset of cognitive impairment, was associated with increased neurofibrillary tangle burden. Impaired hearing in those with cognitive impairment was associated with microinfarcts and neocortical Lewy bodies but not typical Alzheimer disease pathologic change. Functional hearing problems may be a preclinical marker of neurofibrillary neurodegeneration, although replication is needed.


Assuntos
Doença de Alzheimer/patologia , Encéfalo/patologia , Perda Auditiva/patologia , Placa Amiloide/patologia , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/complicações , Autopsia , Feminino , Perda Auditiva/complicações , Humanos , Corpos de Lewy/patologia , Masculino , Emaranhados Neurofibrilares/patologia
4.
BMC Neurol ; 20(1): 317, 2020 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-32854643

RESUMO

BACKGROUND: The ventricular system plays a vital role in blood-cerebrospinal fluid (CSF) exchange and interstitial fluid-CSF drainage pathways. CSF is formed in the specialized secretory tissue called the choroid plexus, which consists of epithelial cells, fenestrated capillaries and the highly vascularized stroma. Very little is currently known about the role played by the ventricles and the choroid plexus tissue in aging and Alzheimer's disease (AD). METHODS: In this study, we used our state-of-the-art proteomic platform, a liquid chromatography/mass spectrometry (LC-MS/MS) approach coupled with Tandem Mass Tag isobaric labeling to conduct a detailed unbiased proteomic analyses of autopsied tissue isolated from the walls of the inferior horn of the lateral ventricles in AD (77.2 ± 0.6 yrs), age-matched controls (77.0 ± 0.5 yrs), and nonagenarian cases (93.2 ± 1.1 yrs). RESULTS: Ingenuity pathway analyses identified phagosome maturation, impaired tight-junction signaling, and glucose/mannose metabolism as top significantly regulated pathways in controls vs nonagenarians. In matched-control vs AD cases we identified alterations in mitochondrial bioenergetics, oxidative stress, remodeling of epithelia adherens junction, macrophage recruitment and phagocytosis, and cytoskeletal dynamics. Nonagenarian vs AD cases demonstrated augmentation of oxidative stress, changes in gluconeogenesis-glycolysis pathways, and cellular effects of choroidal smooth muscle cell vasodilation. Amyloid plaque score uniquely correlated with remodeling of epithelial adherens junctions, Fc γ-receptor mediated phagocytosis, and alterations in RhoA signaling. Braak staging was uniquely correlated with altered iron homeostasis, superoxide radical degradation and phagosome maturation. CONCLUSIONS: These changes provide novel insights to explain the compromise to the physiological properties and function of the ventricles/choroid plexus system in nonagenarian aging and AD pathogenesis. The pathways identified could provide new targets for therapeutic strategies to mitigate the divergent path towards AD.


Assuntos
Doença de Alzheimer/fisiopatologia , Encéfalo/patologia , Ventrículos Laterais/patologia , Idoso , Idoso de 80 Anos ou mais , Envelhecimento , Doença de Alzheimer/líquido cefalorraquidiano , Ventrículos Cerebrais/patologia , Plexo Corióideo/patologia , Cromatografia Líquida , Feminino , Humanos , Masculino , Placa Amiloide/patologia , Proteômica , Espectrometria de Massas em Tandem
5.
PLoS One ; 15(7): e0235979, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32706773

RESUMO

Alzheimer's disease (AD) is proposed to be induced by abnormal aggregation of amyloidß in the brain. Here, we designed a brain-permeable peptide nanofiber drug from a fragment of heat shock protein to suppress aggregation of the pathogenic proteins. To facilitate delivery of the nanofiber into the brain, a protein transduction domain from Drosophila Antennapedia was incorporated into the peptide sequence. The resulting nanofiber efficiently suppressed the cytotoxicity of amyloid ßby trapping amyloid ß onto its hydrophobic nanofiber surface. Moreover, the intravenously or intranasally injected nanofiber was delivered into the mouse brain, and improved the cognitive function of an Alzheimer transgenic mouse model. These results demonstrate the potential therapeutic utility of nanofibers for the treatment of AD.


Assuntos
Doença de Alzheimer/prevenção & controle , Peptídeos beta-Amiloides/administração & dosagem , Encéfalo/metabolismo , Modelos Animais de Doenças , Transtornos da Memória/prevenção & controle , Nanofibras/administração & dosagem , Placa Amiloide/prevenção & controle , Administração Intranasal , Doença de Alzheimer/etiologia , Doença de Alzheimer/patologia , Animais , Encéfalo/efeitos dos fármacos , Feminino , Transtornos da Memória/etiologia , Transtornos da Memória/patologia , Camundongos , Camundongos Transgênicos , Nanofibras/química , Placa Amiloide/etiologia , Placa Amiloide/patologia
7.
J Neurosci ; 40(28): 5347-5361, 2020 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-32457076

RESUMO

Amyloid-ß (Aß) deposition occurs years before cognitive symptoms appear and is considered a cause of Alzheimer's disease (AD). The imbalance of Aß production and clearance leads to Aß accumulation and Aß deposition. Increasing evidence indicates an important role of astrocytes, the most abundant cell type among glial cells in the brain, in Aß clearance. We explored the role of low-density lipoprotein receptor-related protein 4 (LRP4), a member of the LDLR family, in AD pathology. We show that Lrp4 is specifically expressed in astrocytes and its levels in astrocytes were higher than those of Ldlr and Lrp1, both of which have been implicated in Aß uptake. LRP4 was reduced in postmortem brain tissues of AD patients. Genetic deletion of the Lrp4 gene augmented Aß plaques in 5xFAD male mice, an AD mouse model, and exacerbated the deficits in neurotransmission, synchrony between the hippocampus and PFC, and cognition. Mechanistically, LRP4 promotes Aß uptake by astrocytes likely by interacting with ApoE. Together, our study demonstrates that astrocytic LRP4 plays an important role in Aß pathology and cognitive function.SIGNIFICANCE STATEMENT This study investigates how astrocytes, a type of non-nerve cells in the brain, may contribute to Alzheimer's disease (AD) development. We demonstrate that the low-density lipoprotein receptor-related protein 4 (LRP4) is reduced in the brain of AD patients. Mimicking the reduced levels in an AD mouse model exacerbates cognitive impairment and increases amyloid aggregates that are known to damage the brain. We show that LRP4 could promote the clearance of amyloid protein by astrocytes. Our results reveal a previously unappreciated role of LRP4 in AD development.


Assuntos
Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Astrócitos/metabolismo , Encéfalo/metabolismo , Proteínas Relacionadas a Receptor de LDL/metabolismo , Doença de Alzheimer/patologia , Animais , Astrócitos/patologia , Encéfalo/patologia , Modelos Animais de Doenças , Feminino , Humanos , Proteínas Relacionadas a Receptor de LDL/genética , Masculino , Camundongos , Placa Amiloide/metabolismo , Placa Amiloide/patologia
8.
Nat Methods ; 17(5): 531-540, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32371980

RESUMO

Single-molecule localization microscopy is a powerful tool for visualizing subcellular structures, interactions and protein functions in biological research. However, inhomogeneous refractive indices inside cells and tissues distort the fluorescent signal emitted from single-molecule probes, which rapidly degrades resolution with increasing depth. We propose a method that enables the construction of an in situ 3D response of single emitters directly from single-molecule blinking datasets, and therefore allows their locations to be pinpointed with precision that achieves the Cramér-Rao lower bound and uncompromised fidelity. We demonstrate this method, named in situ PSF retrieval (INSPR), across a range of cellular and tissue architectures, from mitochondrial networks and nuclear pores in mammalian cells to amyloid-ß plaques and dendrites in brain tissues and elastic fibers in developing cartilage of mice. This advancement expands the routine applicability of super-resolution microscopy from selected cellular targets near coverslips to intra- and extracellular targets deep inside tissues.


Assuntos
Encéfalo/metabolismo , Cartilagem/metabolismo , Imageamento Tridimensional/métodos , Microscopia de Fluorescência/métodos , Nanotecnologia/métodos , Placa Amiloide/metabolismo , Imagem Individual de Molécula/métodos , Animais , Encéfalo/patologia , Cartilagem/patologia , Núcleo Celular/metabolismo , Células Cultivadas , Interpretação de Imagem Assistida por Computador/métodos , Masculino , Camundongos , Mitocôndrias/metabolismo , Imagem Molecular/métodos , Poro Nuclear/metabolismo , Placa Amiloide/patologia
9.
Sci Rep ; 10(1): 5888, 2020 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-32246090

RESUMO

Amyloid plaques composed of Aß amyloid peptides and neurofibrillary tangles are a pathological hallmark of Alzheimer's disease. In situ identification of early-stage amyloid aggregates in Alzheimer's disease is relevant for their importance as potential targets for effective drugs. Synchrotron-based infrared imaging is here used to identify early-stage oligomeric/granular aggregated amyloid species in situ in the brain of APP/PS1 transgenic mice and Octodon degus for the first time. Also, APP/PS1 mice show fibrillary aggregates at 6 and 12 months whereas very little formation of fibrils is found in aged Octodon degus. Finally, significant decreased burden of early-stage aggregates and fibrillary aggregates is obtained following treatment with G4-His-Mal dendrimers (a neurodegenerative protector) in 6-month-old APP/PS1 mice, thus demonstrating putative therapeutic properties of G4-His-Mal dendrimers in AD models. Identification, localization, and characterization using infrared imaging of these non-fibrillary species in the cerebral cortex at early stages of AD progression in transgenic mice point to their relevance as putative pharmacological targets. No less important, early detection of these structures may be useful in the search for markers for non-invasive diagnostic techniques.


Assuntos
Doença de Alzheimer/patologia , Placa Amiloide/patologia , Fatores Etários , Doença de Alzheimer/diagnóstico , Animais , Encéfalo/patologia , Modelos Animais de Doenças , Masculino , Camundongos , Camundongos Transgênicos , Octodon , Espectroscopia de Infravermelho com Transformada de Fourier , Síncrotrons
10.
Nat Med ; 26(3): 398-407, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32161412

RESUMO

Development of tau-based therapies for Alzheimer's disease requires an understanding of the timing of disease-related changes in tau. We quantified the phosphorylation state at multiple sites of the tau protein in cerebrospinal fluid markers across four decades of disease progression in dominantly inherited Alzheimer's disease. We identified a pattern of tau staging where site-specific phosphorylation changes occur at different periods of disease progression and follow distinct trajectories over time. These tau phosphorylation state changes are uniquely associated with structural, metabolic, neurodegenerative and clinical markers of disease, and some (p-tau217 and p-tau181) begin with the initial increases in aggregate amyloid-ß as early as two decades before the development of aggregated tau pathology. Others (p-tau205 and t-tau) increase with atrophy and hypometabolism closer to symptom onset. These findings provide insights into the pathways linking tau, amyloid-ß and neurodegeneration, and may facilitate clinical trials of tau-based treatments.


Assuntos
Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Amiloide/metabolismo , Padrões de Herança/genética , Proteínas tau/metabolismo , Adulto , Idoso , Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/diagnóstico por imagem , Atrofia , Encéfalo/patologia , Cognição , Progressão da Doença , Feminino , Fluordesoxiglucose F18/química , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Neuroimagem , Fosforilação , Placa Amiloide/patologia , Solubilidade , Proteínas tau/líquido cefalorraquidiano
11.
Proc Natl Acad Sci U S A ; 117(12): 6844-6854, 2020 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-32144141

RESUMO

Chronic inflammation during Alzheimer's disease (AD) is most often attributed to sustained microglial activation in response to amyloid-ß (Aß) plaque deposits and cell death. However, cytokine release and microgliosis are consistently observed in AD transgenic animal models devoid of such pathologies, bringing into question the underlying processes that may be at play during the earliest AD-related immune response. We propose that this plaque-independent inflammatory reaction originates from neurons burdened with increasing levels of soluble and oligomeric Aß, which are known to be the most toxic amyloid species within the brain. Laser microdissected neurons extracted from preplaque amyloid precursor protein (APP) transgenic rats were found to produce a variety of potent immune factors, both at the transcript and protein levels. Neuron-derived cytokines correlated with the extent of microglial activation and mobilization, even in the absence of extracellular plaques and cell death. Importantly, we identified an inflammatory profile unique to Aß-burdened neurons, since neighboring glial cells did not express similar molecules. Moreover, we demonstrate within disease-vulnerable regions of the human brain that a neuron-specific inflammatory response may precede insoluble Aß plaque and tau tangle formation. Thus, we reveal the Aß-burdened neuron as a primary proinflammatory agent, implicating the intraneuronal accumulation of Aß as a significant immunological component in the AD pathogenesis.


Assuntos
Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Encéfalo/patologia , Inflamação/patologia , Neurônios/imunologia , Placa Amiloide/patologia , Doença de Alzheimer/imunologia , Doença de Alzheimer/metabolismo , Amiloidose , Animais , Encéfalo/imunologia , Encéfalo/metabolismo , Modelos Animais de Doenças , Feminino , Humanos , Inflamação/imunologia , Inflamação/metabolismo , Masculino , Neurônios/metabolismo , Neurônios/patologia , Placa Amiloide/imunologia , Placa Amiloide/metabolismo , Ratos , Ratos Transgênicos
12.
Am J Pathol ; 190(6): 1323-1331, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32201261

RESUMO

Amyloid ß-proteins (Aßs) Aß1-42 and Aß1-43 are converted via two product lines of γ-secretase to Aß1-38 and Aß1-40. This parallel stepwise processing model of γ-secretase predicts that Aß1-42 and Aß1-43, and Aß1-38 and Aß1-40 are proportional to each other, respectively. To obtain further insight into the mechanisms of parenchymal Aß deposition, these four Aß species were quantified in insoluble fractions of human brains (Brodmann areas 9 to 11) at various Braak senile plaque (SP) stages, using specific enzyme-linked immunosorbent assays. With advancing SP stages, the amounts of deposited Aß1-43 in the brain increased proportionally to those of Aß1-42. Similarly, the amounts of deposited Aß1-38 correlated with those of Aß1-40. Surprisingly, the ratios of deposited Aß1-38/Aß1-42 and Aß1-40/Aß1-43 were proportional and discriminated the Braak SP stages accurately. This result indicates that the generation of Aß1-38 and Aß1-40 decreased and the generation of Aß1-42 and Aß1-43 increased with advancing SP stages. Thus, Aßs deposition might depend on γ-secretase activity, as it does in the cerebrospinal fluid. Here, the extracted γ-secretase from Alzheimer disease brains generates an amount of Aß1-42 and Aß1-43 compared with cognitively normal brains. This refractory γ-secretase localized in detergent-solubilized fractions from brain cortices. But activity modulated γ-secretase, which decreases Aß1-42 and Aß1-43 in the cerebrospinal fluid, localized in detergent-insoluble fractions. These drastic alterations reflect Aß situation in Alzheimer disease brains.


Assuntos
Doença de Alzheimer/metabolismo , Secretases da Proteína Precursora do Amiloide/metabolismo , Encéfalo/metabolismo , Placa Amiloide/metabolismo , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Encéfalo/patologia , Progressão da Doença , Feminino , Humanos , Masculino , Placa Amiloide/patologia
13.
Molecules ; 25(4)2020 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-32079064

RESUMO

CRANAD-28, a difluoroboron curcumin analogue, has been demonstrated in earlier reports to successfully label amyloid beta (Aß) plaques for imaging both ex vivo and in vivo. CRANAD-28's imaging brightness, ability to penetrate the blood brain barrier, and low toxicity make the compound a potentially potent imaging tool in Alzheimer's research. In this study, the Aß-labeling ability of CRANAD-28 was investigated in further detail using histological staining to assess different criteria, including stained Aß plaque brightness, Aß plaque size, and Aß plaque number count. The results of this study demonstrated CRANAD-28 to be superior across all criteria assessed. Furthermore, CRANAD-28 and IBA-1 antibody were used to label Aß-plaques and microglia respectively. Statistical analysis with Spearman regression revealed a statistically significant negative correlation between the size of labeled Aß plaques and surrounding microglia density. This finding provides interesting insight into Aß plaque and microglia dynamism in AD pathology and corroborates the findings of previous studies. In addition, we found that CRANAD-28 provided distinct spectral signatures for Aßs in the core and periphery of the plaques. Based on the study's results, CRANAD-28 could be considered as an alternative standard for imaging Aß-plaques in future research studies.


Assuntos
Compostos de Boro/química , Encéfalo/ultraestrutura , Curcumina/química , Corantes Fluorescentes/química , Microglia/ultraestrutura , Placa Amiloide/ultraestrutura , Doença de Alzheimer , Animais , Benzotiazóis/química , Encéfalo/metabolismo , Modelos Animais de Doenças , Feminino , Humanos , Camundongos , Camundongos Transgênicos , Microglia/metabolismo , Microglia/patologia , Microscopia Confocal , Microtomia , Placa Amiloide/metabolismo , Placa Amiloide/patologia , Coloração e Rotulagem/métodos
14.
Int J Mol Sci ; 21(3)2020 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-32050445

RESUMO

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and is the most common form of dementia in the elderly. Caspases, a family of cysteine proteases, are major mediators of apoptosis and inflammation. Caspase-6 is considered to be an up-stream modulator of AD pathogenesis as active caspase-6 is abundant in neuropil threads, neuritic plaques, and neurofibrillary tangles of AD brains. In order to further elucidate the role of caspase-6 activity in the pathogenesis of AD, we produced a double transgenic mouse model, combining the 5xFAD mouse model of AD with caspase-6 knock out (C6-KO) mice. Behavioral examinations of 5xFAD/C6-KO double transgenic mice showed improved performance in spatial learning, memory, and anxiety/risk assessment behavior, as compared to 5xFAD mice. Hippocampal mRNA expression analyses showed significantly reduced levels of inflammatory mediator TNF-α, while the anti-inflammatory cytokine IL-10 was increased in 5xFAD/C6-KO mice. A significant reduction in amyloid-ß plaques could be observed and immunohistochemistry analyses showed reduced levels of activated microglia and astrocytes in 5xFAD/C6-KO, compared to 5xFAD mice. Together, these results indicate a substantial role for caspase-6 in the pathology of the 5xFAD model of AD and suggest further validation of caspase-6 as a potential therapeutic target for AD.


Assuntos
Doença de Alzheimer/genética , Caspase 6/genética , Doença de Alzheimer/patologia , Doença de Alzheimer/fisiopatologia , Animais , Modelos Animais de Doenças , Feminino , Deleção de Genes , Masculino , Memória , Camundongos , Camundongos Knockout , Mutação , Placa Amiloide/genética , Placa Amiloide/patologia , Placa Amiloide/fisiopatologia , Aprendizagem Espacial
15.
J Neuroimmunol ; 341: 577185, 2020 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-32045774

RESUMO

Alzheimer's disease (AD) is the most common dementia type affecting nearly 44 million people worldwide. Recent findings point to microglia as a significant contributor to neural development, neuroinflammation, and degeneration. Dysregulated immunoactivity in AD has been broadly studied, and current research on animal models enabled us to identify a new cluster of microglia (disease-associated microglia) alongside previously detected glial populations (e.g., plaque-associated microglia, dark microglia, Human Alzheimer's microglia) associated with neuroinflammation and with macrophagic activity. These distinct populations of glia show a spatial distribution within plaques with unique imaging features and distinct gene expression profile. Novel genetic approaches using single-nuclei RNA sequencing (sn-RNA seq) allowed researchers to identify gene expression profiles from fixed human samples. Recent studies, exposing transcriptomic clusters of disease-related cells and analyzing sequenced RNA from sorted myeloid cells, seem to confirm the hypothesis of the central role of glia in the pathogenesis of Alzheimer's disease. These discoveries may shed light on the effects of microglial activation and differences in gene expression profiles, furthering research towards the development of a cell-specific therapy. In this review, we examine recent studies that guide us towards recognizing the role of diverse populations of glial cells and their possible heterogeneous functional states in the pathogenesis of AD in humans.


Assuntos
Doença de Alzheimer/imunologia , Microglia/imunologia , Degeneração Neural/imunologia , Proteínas Adaptadoras de Transdução de Sinal/deficiência , Doença de Alzheimer/patologia , Animais , Modelos Animais de Doenças , Proteínas do Olho/fisiologia , Perfilação da Expressão Gênica , Humanos , Glicoproteínas de Membrana/deficiência , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/fisiologia , Camundongos , Microglia/classificação , Microglia/metabolismo , Microglia/patologia , Degeneração Neural/patologia , Fatores de Crescimento Neural/fisiologia , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Placa Amiloide/imunologia , Placa Amiloide/patologia , Receptores Imunológicos/deficiência , Receptores Imunológicos/genética , Receptores Imunológicos/fisiologia , Serpinas/fisiologia , Transcriptoma
16.
Cell Mol Life Sci ; 77(24): 5243-5258, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32034429

RESUMO

Synaptic functional disturbances with concomitant synapse loss represent central pathological hallmarks of Alzheimer's disease. Excessive accumulation of cytotoxic amyloid oligomers is widely recognized as a key event that underlies neurodegeneration. Certain complement components are crucial instruments of widespread synapse loss because they can tag synapses with functional impairments leading to their engulfment by microglia. However, an exact understanding of the affected synaptic functions that predispose to complement-mediated synapse elimination is lacking. Therefore, we conducted systematic proteomic examinations on synaptosomes prepared from an amyloidogenic mouse model of Alzheimer's disease (APP/PS1). Synaptic fractions were separated according to the presence of the C1q-tag using fluorescence-activated synaptosome sorting and subjected to proteomic comparisons. The results raised the decline of mitochondrial functions in the C1q-tagged synapses of APP/PS1 mice based on enrichment analyses, which was verified using flow cytometry. Additionally, proteomics results revealed extensive alterations in the level of septin protein family members, which are known to dynamically form highly organized pre- and postsynaptic supramolecular structures, thereby affecting synaptic transmission. High-resolution microscopy investigations demonstrated that synapses with considerable amounts of septin-3 and septin-5 show increased accumulation of C1q in APP/PS1 mice compared to the wild-type ones. Moreover, a strong positive correlation was apparent between synaptic septin-3 levels and C1q deposition as revealed via flow cytometry and confocal microscopy examinations. In sum, our results imply that deterioration of synaptic mitochondrial functions and alterations in the organization of synaptic septins are associated with complement-dependent synapse loss in Alzheimer's disease.


Assuntos
Doença de Alzheimer/genética , Amiloide/metabolismo , Proteoma/genética , Sinapses/genética , Doença de Alzheimer/patologia , Amiloide/toxicidade , Proteínas Amiloidogênicas/genética , Animais , Modelos Animais de Doenças , Regulação da Expressão Gênica/genética , Humanos , Camundongos , Microglia/metabolismo , Microglia/patologia , Mitocôndrias/genética , Mitocôndrias/patologia , Oligopeptídeos/genética , Placa Amiloide/genética , Placa Amiloide/patologia , Septinas/genética , Sinapses/metabolismo , Sinapses/patologia , Sinaptossomos/metabolismo , Sinaptossomos/patologia
17.
J Neurosci ; 40(7): 1581-1593, 2020 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-31915254

RESUMO

Alzheimer's disease (AD) is the most common neurodegenerative disorder, resulting in the progressive decline of cognitive function in patients. Familial forms of AD are tied to mutations in the amyloid precursor protein, but the cellular mechanisms that cause AD remain unclear. Inflammation and amyloidosis from amyloid ß (Aß) aggregates are implicated in neuron loss and cognitive decline. Inflammation activates the protein-tyrosine phosphatase 1B (PTP1B), and this could suppress many signaling pathways that activate glycogen synthase kinase 3ß (GSK3ß) implicated in neurodegeneration. However, the significance of PTP1B in AD pathology remains unclear. Here, we show that pharmacological inhibition of PTP1B with trodusquemine or selective ablation of PTP1B in neurons prevents hippocampal neuron loss and spatial memory deficits in a transgenic AD mouse model with Aß pathology (hAPP-J20 mice of both sexes). Intriguingly, while systemic inhibition of PTP1B reduced inflammation in the hippocampus, neuronal PTP1B ablation did not. These results dissociate inflammation from neuronal loss and cognitive decline and demonstrate that neuronal PTP1B hastens neurodegeneration and cognitive decline in this model of AD. The protective effect of PTP1B inhibition or ablation coincides with the restoration of GSK3ß inhibition. Neuronal ablation of PTP1B did not affect cerebral amyloid levels or plaque numbers, but reduced Aß plaque size in the hippocampus. In summary, our preclinical study suggests that targeting PTP1B may be a new strategy to intervene in the progression of AD.SIGNIFICANCE STATEMENT Familial forms of Alzheimer's disease (AD) are tied to mutations in the amyloid precursor protein, but the cellular mechanisms that cause AD remain unclear. Here, we used a mouse model expressing human amyloid precursor protein bearing two familial mutations and asked whether activation of a phosphatase PTP1B participates in the disease process. Systemic inhibition of this phosphatase using a selective inhibitor prevented cognitive decline, neuron loss in the hippocampus, and attenuated inflammation. Importantly, neuron-targeted ablation of PTP1B also prevented cognitive decline and neuron loss but did not reduce inflammation. Therefore, neuronal loss rather than inflammation was critical for AD progression in this mouse model, and that disease progression could be ameliorated by inhibition of PTP1B.


Assuntos
Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Proteínas do Tecido Nervoso/fisiologia , Proteína Tirosina Fosfatase não Receptora Tipo 1/fisiologia , Memória Espacial/fisiologia , Peptídeos beta-Amiloides/análise , Animais , Colestanos/farmacologia , Modelos Animais de Doenças , Feminino , Glicogênio Sintase Quinase 3 beta/fisiologia , Hipocampo/efeitos dos fármacos , Hipocampo/patologia , Humanos , Inflamação , Resistência à Insulina , Masculino , Aprendizagem em Labirinto , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação , Proteínas do Tecido Nervoso/antagonistas & inibidores , Fragmentos de Peptídeos/análise , Placa Amiloide/patologia , Proteína Tirosina Fosfatase não Receptora Tipo 1/antagonistas & inibidores , Proteínas Recombinantes/metabolismo , Memória Espacial/efeitos dos fármacos , Espermina/análogos & derivados , Espermina/farmacologia
18.
Psychopharmacology (Berl) ; 237(4): 1233-1243, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31953648

RESUMO

RATIONALE AND OBJECTIVE: Vortioxetine has been reported to exhibit a variety of neurobiological functions and neuroprotective effects. In the present study, we aimed to investigate the effects of vortioxetine on cognitive performance in a transgenic mouse model of Alzheimer's disease (AD). METHODS: We administered vortioxetine (10 mg/kg, i.p., every day, for approximately 6 weeks), which acts on multiple 5-serotonin (5-HT) receptors, to 3.5-month-old 5×FAD mice. Subsequently, we used the open field (OF) test to detect anxiety-like behavior in the mice. The novel object recognition (NOR) test and Morris water maze (MWM) were used to assess the cognitive states of the 5×FAD mice. We also measured the levels of insoluble amyloid plaques and soluble ß-amyloid (Aß) plaques. Finally, we explored the expression levels of postsynaptic density protein 95 (PSD95), synaptophysin (SYP), and synaptotagmin-1 (SYT1) in the hippocampus of the mice. RESULTS: The administration of vortioxetine effectively reversed the reduction in anxiety-type behaviors in 5×FAD mice and improved the impairment in recognition memory and spatial reference memory. However, we did not find that vortioxetine decreased or delayed the formation of amyloid plaques or Aß. Interestingly, we found a significant increase in the expression levels of PSD95, SYP, and SYT1 in the 5×FAD mice after vortioxetine treatment compared with the control group. CONCLUSION: These results demonstrate that vortioxetine may improve cognitive impairment in 5×FAD mice. The role in cognitive improvement may be related to the beneficial effects of vortioxetine on synaptic function.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Disfunção Cognitiva/tratamento farmacológico , Fármacos Neuroprotetores/uso terapêutico , Sinapses/efeitos dos fármacos , Vortioxetina/uso terapêutico , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Animais , Disfunção Cognitiva/genética , Disfunção Cognitiva/patologia , Flavina-Adenina Dinucleotídeo/genética , Hipocampo/efeitos dos fármacos , Hipocampo/patologia , Humanos , Aprendizagem em Labirinto/efeitos dos fármacos , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Transgênicos , Fármacos Neuroprotetores/farmacologia , Placa Amiloide/tratamento farmacológico , Placa Amiloide/genética , Placa Amiloide/patologia , Sinapses/patologia , Vortioxetina/farmacologia
19.
J Neurosci ; 40(9): 1956-1974, 2020 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-31980586

RESUMO

TREM2 is an Alzheimer's disease (AD) risk gene expressed in microglia. To study the role of Trem2 in a mouse model of ß-amyloidosis, we compared PS2APP transgenic mice versus PS2APP mice lacking Trem2 (PS2APP;Trem2ko) at ages ranging from 4 to 22 months. Microgliosis was impaired in PS2APP;Trem2ko mice, with Trem2-deficient microglia showing compromised expression of proliferation/Wnt-related genes and marked accumulation of ApoE. Plaque abundance was elevated in PS2APP;Trem2ko females at 6-7 months; but by 12 or 19-22 months of age, it was notably diminished in female and male PS2APP;Trem2ko mice, respectively. Across all ages, plaque morphology was more diffuse in PS2APP;Trem2ko brains, and the Aß42:Aß40 ratio was elevated. The amount of soluble, fibrillar Aß oligomers also increased in PS2APP;Trem2ko hippocampi. Associated with these changes, axonal dystrophy was exacerbated from 6 to 7 months onward in PS2APP;Trem2ko mice, notwithstanding the reduced plaque load at later ages. PS2APP;Trem2ko mice also exhibited more dendritic spine loss around plaque and more neurofilament light chain in CSF. Thus, aggravated neuritic dystrophy is a more consistent outcome of Trem2 deficiency than amyloid plaque load, suggesting that the microglial packing of Aß into dense plaque is an important neuroprotective activity.SIGNIFICANCE STATEMENT Genetic studies indicate that TREM2 gene mutations confer increased Alzheimer's disease (AD) risk. We studied the effects of Trem2 deletion in the PS2APP mouse AD model, in which overproduction of Aß peptide leads to amyloid plaque formation and associated neuritic dystrophy. Interestingly, neuritic dystrophies were intensified in the brains of Trem2-deficient mice, despite these mice displaying reduced plaque accumulation at later ages (12-22 months). Microglial clustering around plaques was impaired, plaques were more diffuse, and the Aß42:Aß40 ratio and amount of soluble, fibrillar Aß oligomers were elevated in Trem2-deficient brains. These results suggest that the Trem2-dependent compaction of Aß into dense plaques is a protective microglial activity, limiting the exposure of neurons to toxic Aß species.


Assuntos
Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Axônios/patologia , Espinhas Dendríticas/patologia , Glicoproteínas de Membrana/genética , Fragmentos de Peptídeos/metabolismo , Placa Amiloide/genética , Receptores Imunológicos/genética , Fator Trefoil-1/metabolismo , Animais , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microglia/patologia , Neuritos/patologia , Proteínas de Neurofilamentos/líquido cefalorraquidiano , Placa Amiloide/patologia
20.
Int J Mol Sci ; 21(3)2020 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-31991844

RESUMO

Zinc and apolipoprotein E (apoE) are reportedly involved in the pathology of Alzheimer's disease. To investigate the associative interaction among zinc, apoE, and amyloid-ß (Aß) and its role in amyloid pathogenesis, we performed various biochemical and immunoreactive analyses using brain tissues of Tg2576 mice and synthetic Aß and apoE peptides. On amyloid plaques or in brain lysates of Tg2576 mice, apoE and Aß immunoreactivities increased after zinc chelation and were restored by its subsequent replacement. Zinc depletion dissociated apoE/Aß complexes or larger-molecular sizes of Aß oligomers/aggregates into smaller-molecular sizes of apoE and/or Aß monomers/complexes. In the presence of zinc, synthetic apoE and/or Aß peptides aggregated into larger-molecular sizes of oligomers or complexes. Endogenous proteases or plasmin in brain lysates degraded apoE and/or Aß complexes, and their proteolytic activity increased with zinc depletion. These biochemical findings suggest that zinc associates with apoE and Aß to encourage the formation of apoE/Aß complexes or large aggregates, raising the deposition of zinc-rich amyloid plaques. In turn, the presence of abundant zinc around and within apoE/Aß complexes may block the access or activity of Aß-degrading antibodies or proteases. These results support the plausibility of chelation strategy aiming at reducing amyloid pathology in Alzheimer's disease.


Assuntos
Peptídeos beta-Amiloides/metabolismo , Amiloide/metabolismo , Apolipoproteínas E/metabolismo , Placa Amiloide/metabolismo , Placa Amiloide/patologia , Zinco/metabolismo , Animais , Modelos Animais de Doenças , Humanos , Camundongos , Agregados Proteicos , Agregação Patológica de Proteínas , Ligação Proteica
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...