Alzheimer’s disease brain-derived tau-containing extracellular vesicles: Pathobiology and GABAergic neuronal transmission

AbstractExtracellular vesicles (EVs) propagate tau pathology for Alzheimer’s disease (AD). How EV transmission influences AD are, nonetheless, poorly understood. To these ends, the physicochemical and molecular structure-function relationships of human brain-derived EVs, from AD and prodromal AD (pAD), were compared to non-demented controls (CTRL). AD EVs were shown to be significantly enriched in epitope-specific tau oligomers versus pAD or CTRL EVs assayed by dot-blot and atomic force microscopy tests. AD EVs were efficiently internalized by murine cortical neurons and transferred tau with higher aggregation potency than pAD and CTRL EVs. Strikingly, inoculation of tau-containing AD EVs into the outer molecular layer of the dentate gyrus induced tau propagation throughout the hippocampus. This was seen in 22 months-old C57BL/6 mice at 4.5 months post-injection by semiquantitative brain-wide immunohistochemistry tests with multiple anti-phospho-tau (p-tau) antibodies. Inoculation of the equal amount of tau from CTRL EVs or as oligomer or fibril-enriched fraction from the same AD donor showed little propagation. AD EVs induced tau accumulation in the hippocampus as oligomers or sarkosyl-insoluble proteins. Unexpectedly, p-tau cells were mostly GAD67+ GABAergic neurons and to a lesser extent, GluR2/3+ excitatory mossy cells, showing preferential EV-mediated GABAergic neuronal tau propagation. Whole-cell patch clamp recording of Cornu Ammonis (CA1) pyramidal cells showed significant reduction in the amplitude of spontaneous inhibitory post-synaptic currents. This was accompanied by reductions in c-fos+ GAD67+GABAergic neurons and GAD67+ GABAergic neuronal puncta surrounding pyramidal neurons in the CA1 region confirming reduced interneuronal projections. Our study posits a novel tau-associated pathological mechanism for brain-derived EVs.

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Reduction of Dendritic Inhibition in CA1 Pyramidal Neurons in Amyloidosis Models of Early Alzheimer’s Disease

Journal of Alzheimer s Disease ◽

10.3233/jad-200527 ◽

2020 ◽

Vol 78 (3) ◽

pp. 951-964

Author(s):

Marvin Ruiter ◽

Lotte J. Herstel ◽

Corette J. Wierenga

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Action Potentials ◽

Pyramidal Neurons ◽

Early Stage ◽

Brain Slices ◽

Pyramidal Cells ◽

Excitatory Input ◽

Aβ Oligomers ◽

Ca1 Pyramidal Neurons

Background: In an early stage of Alzheimer’s disease (AD), before the formation of amyloid plaques, neuronal network hyperactivity has been reported in both patients and animal models. This suggests an underlying disturbance of the balance between excitation and inhibition. Several studies have highlighted the role of somatic inhibition in early AD, while less is known about dendritic inhibition. Objective: In this study we investigated how inhibitory synaptic currents are affected by elevated Aβ levels. Methods: We performed whole-cell patch clamp recordings of CA1 pyramidal neurons in organotypic hippocampal slice cultures after treatment with Aβ-oligomers and in hippocampal brain slices from AppNL-F-G mice (APP-KI). Results: We found a reduction of spontaneous inhibitory postsynaptic currents (sIPSCs) in CA1 pyramidal neurons in organotypic slices after 24 h Aβ treatment. sIPSCs with slow rise times were reduced, suggesting a specific loss of dendritic inhibitory inputs. As miniature IPSCs and synaptic density were unaffected, these results suggest a decrease in activity-dependent transmission after Aβ treatment. We observed a similar, although weaker, reduction in sIPSCs in CA1 pyramidal neurons from APP-KI mice compared to control. When separated by sex, the strongest reduction in sIPSC frequency was found in slices from male APP-KI mice. Consistent with hyperexcitability in pyramidal cells, dendritically targeting interneurons received slightly more excitatory input. GABAergic action potentials had faster kinetics in APP-KI slices. Conclusion: Our results show that Aβ affects dendritic inhibition via impaired action potential driven release, possibly due to altered kinetics of GABAergic action potentials. Reduced dendritic inhibition may contribute to neuronal hyperactivity in early AD.

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Nucleolar PARP-1 Expression Is Decreased in Alzheimer’s Disease: Consequences for Epigenetic Regulation of rDNA and Cognition

Neural Plasticity ◽

10.1155/2016/8987928 ◽

2016 ◽

Vol 2016 ◽

pp. 1-9 ◽

Cited By ~ 18

Author(s):

Jianying Zeng ◽

Jenny Libien ◽

Fatima Shaik ◽

Jason Wolk ◽

A. Iván Hernández

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Pyramidal Neurons ◽

Pyramidal Cells ◽

Hippocampal Pyramidal Neurons ◽

Functional Changes ◽

Epigenetic Regulator ◽

Parp 1 ◽

Sensitive Marker ◽

Hippocampal Pyramidal Cells

Synaptic dysfunction is thought to play a major role in memory impairment in Alzheimer’s disease (AD). PARP-1 has been identified as an epigenetic regulator of plasticity and memory. Thus, we hypothesize that PARP-1 may be altered in postmortem hippocampus of individuals with AD compared to age-matched controls without neurologic disease. We found a reduced level of PARP-1 nucleolar immunohistochemical staining in hippocampal pyramidal cells in AD. Nucleolar PARP-1 staining ranged from dispersed and less intense to entirely absent in AD compared to the distinct nucleolar localization in hippocampal pyramidal neurons in controls. In cases of AD, the percentage of hippocampal pyramidal cells with nucleoli that were positive for both PARP-1 and the nucleolar marker fibrillarin was significantly lower than in controls. PARP-1 nucleolar expression emerges as a sensitive marker of functional changes in AD and suggests a novel role for PARP-1 dysregulation in AD pathology.

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Alix and Syntenin-1 direct amyloid precursor protein trafficking into extracellular vesicles

10.21203/rs.2.22338/v2 ◽

2020 ◽

Author(s):

Allaura S. Cone ◽

Stephanie N. Hurwitz ◽

Glorida S. Lee ◽

Xuegang Yuan ◽

Yi Zhou ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Subcellular Localization ◽

Amyloid Precursor Protein ◽

Extracellular Vesicles ◽

Protein Trafficking ◽

Cortical Neurons ◽

Molecular Mechanisms ◽

Precursor Protein ◽

Amyloid Precursor Protein Trafficking

Abstract Background: Endosomal trafficking and amyloidogenic cleavage of amyloid precursor protein (APP) is believed to play a role in the neurodegeneration observed in Alzheimer’s disease (AD). Recent evidence has suggested that packaging and secretion of APP and its amyloidogenic cleaved product (βAPP) into small extracellular vesicles (EVs) may facilitate uptake of these neurotoxic factors during disease progression. However, the molecular mechanisms underlying trafficking of APP into EVs are poorly understood. Results: In this study, the mechanism and impact of amyloid precursor protein trafficking into extracellular vesicles (EVs) were assessed by a series of inducible gene knockdowns. We demonstrate that vesicle-associated proteins Alix and Syntenin-1 are essential for proper subcellular localization and efficient EV secretion of APP via an endosomal sorting complexes required for transport (ESCRT)-independent pathway. The neurotoxic C-terminal fragment (CTF) of APP is similarly secreted in association with small vesicles. These mechanisms are conserved in terminally differentiated neuron-like cells. Furthermore, knockdown of Alix and Syntenin-1 alters the subcellular localization of APP, sequestering the precursor protein to endoplasmic reticulum and endolysosomal compartments, respectively. Finally, transfer of small EVs containing APP confers an increase in reactive oxygen species production and neurotoxicity to human induced pluripotent stem cell-derived cortical neurons and naïve primary neurons, an effect that is ameliorated by Alix and Syntenin-1 depletion. Conclusions: Altogether these findings elucidate a novel mechanism for understanding the intracellular trafficking of APP and βAPP into secreted extracellular vesicles, and the resultant potential impact on neurotoxicity in the context of Alzheimer’s disease amyloidopathy.

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Alix and Syntenin-1 direct amyloid precursor protein and amyloid beta trafficking into extracellular vesicles

10.21203/rs.2.22338/v1 ◽

2020 ◽

Author(s):

Allaura S. Cone ◽

Stephanie N. Hurwitz ◽

Glorida S. Lee ◽

Xuegang Yuan ◽

Yi Zhou ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Subcellular Localization ◽

Amyloid Precursor Protein ◽

Extracellular Vesicles ◽

Amyloid Beta ◽

Cortical Neurons ◽

Molecular Mechanisms ◽

Precursor Protein ◽

Endosomal Trafficking

Abstract Background: Endosomal trafficking and amyloidogenic cleavage of amyloid precursor protein (APP) is believed to play a role in the neurodegeneration observed in Alzheimer’s disease (AD). Recent evidence has suggested that packaging and secretion of APP and amyloid beta into small extracellular vesicles (EVs) may facilitate uptake of these neurotoxic factors during disease progression. However, the molecular mechanisms underlying trafficking of APP into EVs are poorly understood. Results: In this study, the mechanism and impact of amyloid precursor protein (APP) trafficking into extracellular vesicles (EVs) were assessed by a series of inducible gene knockdowns. We demonstrate that vesicle-associated proteins Alix and Syntenin-1 are essential for proper subcellular localization and efficient EV secretion of APP via an endosomal sorting complexes required for transport (ESCRT)-independent pathway. The neurotoxic metabolite amyloid beta (Aβ) is similarly secreted in association with small vesicles. These mechanisms are conserved in terminally differentiated neuron-like cells. Furthermore, knockdown of Alix and Syntenin-1 alters the subcellular localization of APP, sequestering the precursor protein to endoplasmic reticulum and endolysosomal compartments, respectively. Finally, transfer of small EVs containing APP confers an increase in reactive oxygen species production and neurotoxicity to human induced pluripotent stem cell-derived cortical neurons and naïve primary neurons, an effect that is ameliorated by Alix and Syntenin-1 depletion. Conclusions: Altogether these findings elucidate a novel mechanism for understanding the intracellular trafficking of APP and Aβ into secreted extracellular vesicles, and the resultant potential impact on neurotoxicity in the context of Alzheimer’s disease amyloidopathy.

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Astrocyte- and Neuron-Derived Extracellular Vesicles from Alzheimer’s Disease Patients Effect Complement-Mediated Neurotoxicity

Cells ◽

10.3390/cells9071618 ◽

2020 ◽

Vol 9 (7) ◽

pp. 1618 ◽

Cited By ~ 5

Author(s):

Carlos J. Nogueras-Ortiz ◽

Vasiliki Mahairaki ◽

Francheska Delgado-Peraza ◽

Debamitra Das ◽

Konstantinos Avgerinos ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Cell Viability ◽

Extracellular Vesicles ◽

Cortical Neurons ◽

Membrane Attack Complex ◽

Neurite Density ◽

Complement Inhibitors ◽

Rat Cortical Neurons ◽

And Control

We have previously shown that blood astrocytic-origin extracellular vesicles (AEVs) from Alzheimer’s disease (AD) patients contain high complement levels. To test the hypothesis that circulating EVs from AD patients can induce complement-mediated neurotoxicity involving Membrane Attack Complex (MAC) formation, we assessed the effects of immunocaptured AEVs (using anti-GLAST antibody), in comparison with neuronal-origin (N)EVs (using anti-L1CAM antibody), and nonspecific CD81+ EVs (using anti-CD81 antibody), from the plasma of AD, frontotemporal lobar degeneration (FTLD), and control participants. AEVs (and, less effectively, NEVs) of AD participants induced Membrane Attack Complex (MAC) expression on recipient neurons (by immunohistochemistry), membrane disruption (by EthD-1 assay), reduced neurite density (by Tuj-1 immunohistochemistry), and decreased cell viability (by MTT assay) in rat cortical neurons and human iPSC-derived neurons. Demonstration of decreased cell viability was replicated in a separate cohort of autopsy-confirmed AD patients. These effects were not produced by CD81+ EVs from AD participants or AEVs/NEVs from FTLD or control participants, and were suppressed by the MAC inhibitor CD59 and other complement inhibitors. Our results support the stated hypothesis and should motivate future studies on the roles of neuronal MAC deposition and AEV/NEV uptake, as effectors of neurodegeneration in AD.

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Alzheimer’s disease brain-derived extracellular vesicles spread tau pathology in interneurons

Brain ◽

10.1093/brain/awaa376 ◽

2020 ◽

Cited By ~ 2

Author(s):

Zhi Ruan ◽

Dhruba Pathak ◽

Srinidhi Venkatesan Kalavai ◽

Asuka Yoshii-Kitahara ◽

Satoshi Muraoka ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Extracellular Vesicles ◽

Cortical Neurons ◽

Acid Decarboxylase ◽

Gabaergic Interneurons ◽

Phosphorylated Tau ◽

Tau Pathology ◽

Tau Oligomers ◽

Prodromal Alzheimer’S Disease

Abstract Extracellular vesicles are highly transmissible and play critical roles in the propagation of tau pathology, although the underlying mechanism remains elusive. Here, for the first time, we comprehensively characterized the physicochemical structure and pathogenic function of human brain-derived extracellular vesicles isolated from Alzheimer’s disease, prodromal Alzheimer’s disease, and non-demented control cases. Alzheimer’s disease extracellular vesicles were significantly enriched in epitope-specific tau oligomers in comparison to prodromal Alzheimer’s disease or control extracellular vesicles as determined by dot blot and atomic force microscopy. Alzheimer’s disease extracellular vesicles were more efficiently internalized by murine cortical neurons, as well more efficient in transferring and misfolding tau, than prodromal Alzheimer’s disease and control extracellular vesicles in vitro. Strikingly, the inoculation of Alzheimer’s disease or prodromal Alzheimer’s disease extracellular vesicles containing only 300 pg of tau into the outer molecular layer of the dentate gyrus of 18-month-old C57BL/6 mice resulted in the accumulation of abnormally phosphorylated tau throughout the hippocampus by 4.5 months, whereas inoculation of an equal amount of tau from control extracellular vesicles, isolated tau oligomers, or fibrils from the same Alzheimer’s disease donor showed little tau pathology. Furthermore, Alzheimer’s disease extracellular vesicles induced misfolding of endogenous tau in both oligomeric and sarkosyl-insoluble forms in the hippocampal region. Unexpectedly, phosphorylated tau was primarily accumulated in glutamic acid decarboxylase 67 (GAD67) GABAergic interneurons and, to a lesser extent, glutamate receptor 2/3-positive excitatory mossy cells, showing preferential extracellular vesicle-mediated GABAergic interneuronal tau propagation. Whole-cell patch clamp recordings of CA1 pyramidal cells showed significant reduction in the amplitude of spontaneous inhibitory post-synaptic currents. This was accompanied by reductions in c-fos+ GAD67+ neurons and GAD67+ neuronal puncta surrounding pyramidal neurons in the CA1 region, confirming reduced GABAergic transmission in this region. Our study posits a novel mechanism for the spread of tau in hippocampal GABAergic interneurons via brain-derived extracellular vesicles and their subsequent neuronal dysfunction.

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Kaempferol promotes memory retention and density of hippocampal CA1 neurons in intra-cerebroventricular STZ-induced experimental AD model in Wistar rats

Biologija ◽

10.6001/biologija.v62i3.3368 ◽

2016 ◽

Vol 62 (3) ◽

Cited By ~ 3

Author(s):

Niloufar Darbandi ◽

Matin Ramezani ◽

Fariba Khodagholi ◽

Mitra Noori

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Pyramidal Neurons ◽

Neuronal Damage ◽

Pyramidal Cells ◽

Control Group ◽

Memory Retention ◽

Hippocampal Ca1 ◽

Learning Test ◽

Ca1 Area

Background. Alzheimer’s disease (AD) is a progressive degenerative disease which causes memory disorders, decreases cognitive functions and abilities, and results in behavioural changes. Some studies have indicated that the flavonoids are able to cross the blood–brain barrier and have a positive effect on the reduction of neuronal damage disorders in the brain such as Alzheimer’s disease. Materials and Methods. ICV administration of streptozotocin (3 mg/kg) was done on the first and the third day of the surgery and the animals’ memory was evaluated through passive avoidance tasks. Animals were divided into five groups: Salin-Salin, STZ-Salin, and STZ- different kaempferol doses (5, 7/5, 10 mg/kg). All animals received different doses of kaempferol or saline for 3 weeks starting one day before the surgery. Later, they were put into a learning test. After the memory test, the animals were killed and their brains were fixed with Paraformaldehyde 4%, and tissue processing was done. Finally, density of intact neurons in the CA1 area of the hippocampus in the brains of all groups was investigated. Results. The ICV injections of STZ significantly reduced memory retention and intact pyramidal cells compared to the control group. The kaempferol improved the effects of STZ. Conclusion. Our findings show that kaempferol can optimize cognitive deficits caused by injections of STZ and also has some useful impacts on hippocampal CA1 pyramidal neurons.

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Astrocyte- and neuron-derived extracellular vesicles from Alzheimer’s disease patients effect complement-mediated neurotoxicity

10.1101/2020.04.14.041863 ◽

2020 ◽

Author(s):

Carlos J Nogueras-Ortiz ◽

Vasiliki Mahairaki ◽

Francheska Delgado-Peraza ◽

Debamitra Das ◽

Konstantinos Avgerinos ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Extracellular Vesicles ◽

Cortical Neurons ◽

Membrane Attack Complex ◽

Neurite Density ◽

Complement Inhibitors ◽

Rat Cortical Neurons ◽

And Control ◽

Human Ipsc

AbstractWe have previously shown that blood astrocytic-origin extracellular vesicles (AEVs) from Alzheimer’s disease (AD) patients contain high complement levels. To test the hypothesis that circulating EVs from AD patients can induce complement-mediated neurodegeneration, we assessed the neurotoxicity of immunocaptured AEVs (with anti-GLAST antibody), neuronal-origin NEVs (with anti-L1CAM antibody), and multicellular-origin (with anti-CD81 antibody) EVs from the plasma of AD, frontotemporal lobar degeneration (FTLD) and control participants. AEVs (and, less effectively, NEVs) of AD participants induced Membrane Attack Complex (MAC) expression on recipient neurons, membrane disruption, reduced neurite density, and decreased cell viability in rat cortical neurons and human IPSC-derived neurons. Neurodegenerative effects were not produced by multicellular-origin EVs from AD participants or AEVs/NEVs from FTLD or control participants, and were suppressed by the MAC inhibitor CD59 and other complement inhibitors. Our results support the stated hypothesis and suggest that neuronal MAC deposition is necessary for AEV/NEV-mediated neurodegeneration in AD.

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