Long RNA profiles of human brain extracellular vesicles in Alzheimer's disease
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ABSTRACT: Alzheimer's disease (AD) is the most common neurodegenerative disorder. Extracellular vesicles (EVs) are carriers of nucleic acids, lipids and proteins, and are known to play a significant role in neurodegenerative pathogenesis. The goals of this study are to compare long RNA (exLR) profiling of EVs in normal human brains with which in AD human brain. EVs were isolated from frontal cortex of normal control (n=10) and AD (n=8) donors.
Project description:Alzheimer's disease (AD) is a neurodegenerative disorder characterized by cognitive decline and memory loss. It has been suggested that alterations in energy metabolism, specifically an increase in resting energy expenditure (REE), may be a key factor in the development and progression of AD. Regular physical activity may improve cognitive function in patients with AD, and although the mechanisms are unclear, organ-to-organ communication may play a role. We hypothesize that changes to extracellular vesicles (EVs) in response to regular physical activity might be involved in organ-to-organ communication mediating the improvement to cognitive function caused by regular physical activity in patients with AD. In this experiment, we profiled the microRNA composition of extracellular vesicles (EVs) purified from the blood of sedentary (sedEV) and/or acutely exercised (exEV) mice as part of understanding this hypothesis.
Project description:This dataset contains microarray data from normal controls (aged 20-99 yrs) and Alzheimer's disease cases, from 4 brain regions: hippocampus, entorhinal cortex, superior frontal cortex, post-central gyrus. Changes in expression of synaptic and immune related genes were analyzed, investigating age-related changes and AD-related changes, and region-specific patterns of change. These AD cases were processed simultaneously with the control cases (young and aged) included in GSE11882 (GSE11882 dataset contains data exclusively from normal control brains).
Project description:Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by progressive deterioration of cognitive function. Evidence suggests a role for epigenetic regulation, in particular the cytosine modifications 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC,) in AD. 5hmC is highly enriched in the nervous system and displays neurodevelopment and age-related changes. To determine the role of 5hmC in AD, we performed genome-wide analyses of 5hmC in DNA from prefrontal cortex of post-mortem AD as well as RNA-Seq to correlate changes in methylation status with transcriptional changes. We also utilized the existing AD fly model to further test the functional significance of these epigenetically altered loci. We identified 325 genes containing differentially hydroxymethylated loci (DhMLs) in both the discovery and replication datasets, and these are enriched for pathways involved in neuron projection development and neurogenesis. Of the 325 genes identified, 140 also showed changes in gene expression by RNA-Seq. Proteins encoded by genes identified in the current analysis form direct protein-protein interactions with AD-associated genes, expanding the network of genes implicated in AD. Furthermore, we identified AD-associated single nucleotide polymorphisms (SNPs) located within or near DhMLs, suggesting that these SNPs may identify regions of epigenetic gene regulation that play a role in AD pathogenesis. Finally using the existing AD fly model we showed that some of these genes could modulate the toxicity associated with AD. Our data implicate neuron projection development and neurogenesis pathways as potential targets in AD. These results indicate that incorporating epigenomic and transcriptomic data with GWAS data can expand the known network of genes involved in disease pathogenesis. Combination of epigenome profiling and Drosophila model enables us to identify the epigenetic modifiers of Alzheimer's disease. University of Kentucky Alzheimer's Disease Research Center (3 control, 3 Alzheimer's) and Emory University Alzheimer's Disease Research Center (2 control, 2 Alzheimer's)
Project description:Alzheimer's disease (AD) is the most common type of dementia. Extracellular amyloid β (Aβ) plaques and intracellular Tau-containing neurofibrillary tangles are major AD lesions that identify Alzheimer’s pathology and to neuronal loss. However, given that these structures are also seen in cognitively normal persons (healthy controls, HC) and in persons who have mild cognitive impairment (MCI), extensive efforts have been undertaken to identify other diagnostic or prognostic indicators. Here, we characterized the RNA contents of extracellular vesicles (EVs) in the plasma of age-matched individuals who are healthy or have MCI or AD. Using RNA sequencing analysis, we found that mitochondrial (mt)RNAs, including MT-ND1 through MT-ND6 and other protein-coding and noncoding mtRNAs, were strikingly elevated in MCI- and AD-associated plasma EVs compared with healthy control EVs. In cultured cells derived from astrocytes, microglia, and neurons, exposure to the toxic conditions in the AD environment (Aβ fibers and H2O2), EVs contained mitochondrial structures (as detected by electron microscopy) as well as mitochondrial RNAs. We propose that in the MCI and AD brain environment, toxicity causing mitochondrial damage results in the packaging of mitochondrial components for export in EVs, and further propose that mitochondrial RNAs in plasma EVs are robust diagnostic and prognostic markers in AD.
Project description:The apolipoprotein E (APOE) gene is the strongest genetic risk modifier for Alzheimer's disease (AD), with the APOE4 allele increasing risk and APOE2 decreasing it compared to the common APOE3 allele. Using single-nuclei RNA sequencing of the temporal cortex from APOE2 carriers, APOE3 homozygotes, and APOE4 carriers, we found that AD-associated transcriptomic changes were highly APOE genotype-dependent. Comparing AD with controls, APOE2 carriers showed upregulated synaptic and myelination-related pathways, preserving synapses and myelination at the protein level. Conversely, these pathways were downregulated in APOE3 homozygotes, resulting in reduced synaptic and myelination proteins. In APOE4 carriers, excitatory neurons displayed reduced synaptic pathways similar to APOE3, but oligodendrocytes showed upregulated myelination pathways like APOE2. However, their synaptic and myelination protein levels remained unchanged or increased. APOE4 carriers also showed increased pro-inflammatory signatures in microglia but reduced responses to amyloid-β pathology. These findings reveal APOE genotype-specific molecular alterations in AD across cell types.
Project description:Cognitively normal brains are compared to sporadic AD and Down syndrome brains with AD for comparison of two different forms of Alzheimer's disease
Project description:Alzheimer's disease (AD) is one of the neurodegenerative diseases and characterized by the appearance and accumulation of amyloid-β (Aβ) aggregates and phosphorylated tau with aging. We performed scRNAseq of immene cells in the brain from WT and AD mice.
Project description:APOE4 is the strongest genetic risk factor for Alzheimer's disease (AD), with increased odds ratios in females. Targeting amyloid plaques shows modest improvement in male non-APOE4 carriers. Leveraging single-cell transcriptomics across APOE variants in both sexes, multiplex flow cytometry, and validation in two independent cohorts of APOE4 female AD patients, we identify a new subset of neutrophils interacting with microglia associated with cognitive impairment. This phenotype is defined by increased IL-17 and IL-1 co-expressed gene modules in blood neutrophils and in microglia of cognitively impaired female APOE e4 carriers, showing increased infiltration to the AD brain. APOE4 female IL-17+ neutrophils upregulated the immunosuppressive cytokines IL-10 and TGFB and immune checkpoints, including LAG-3 and PD-1, associated with accelerated immune aging. Deletion of APOE4 in neutrophils reduced this immunosuppressive phenotype and restored the microglial response to neurodegeneration (MGnD), limiting plaque pathology in AD mice. Mechanistically, IL-17F upregulated in APOE4 neutrophils interacts with microglial IL-17RA to suppress the induction of MGnD phenotype, and blocking this axis supported cognitive improvement in AD mice. These findings provide a translational basis to target IL-17F in APOE e4 female carriers with cognitive impairment.
Project description:APOE4 is the strongest genetic risk factor for Alzheimer's disease (AD) with increased odds ratios in females. Targeting amyloid plaques show modest improvement in male non-APOE4 carriers. Leveraging single cell transcriptomics across APOE variants in both sexes, multiplex flow cytometry and validation in two independent cohorts of APOE4 female AD patients, we identify a new subset of neutrophils, interacting with microglia associated with cognitive impairment. This phenotype is defined by increased IL-17 and IL-1 co-expressed gene modules in blood neutrophils and in microglia of cognitively impaired female APOE e4 carriers, showing increased infiltration to the AD brain. APOE4 female IL-17+ neutrophils upregulated the immunosuppressive cytokines IL-10 and TGFb, and immune checkpoints including LAG-3 and PD-1, associated with accelerated immune aging. Deletion of APOE4 in neutrophils reduced this immunosuppressive phenotype and restored microglial response to neurodegeneration (MGnD), limiting plaque pathology in AD mice. Mechanistically, IL-17F upregulated in APOE4 neutrophils interacts with microglial IL-17RA to suppress the induction of MGnD phenotype, and blocking this axis supported cognitive improvement in AD mice. These findings provide a translational basis to target IL-17F in APOE e4 female carriers with cognitive impairment.
Project description:APOE4 is the strongest genetic risk factor for Alzheimer's disease (AD) with increased odds ratios in females. Targeting amyloid plaques show modest improvement in male non-APOE4 carriers. Leveraging transcriptomics across APOE variants in both sexes, multiplex flow cytometry and validation in two independent cohorts of APOE4 female AD patients, we identify a new subset of neutrophils associated with cognitive impairment. This phenotype is defined by increased IL-17 and IL-1 co-expressed gene modules in blood neutrophils of cognitively impaired female APOE e4 carriers, showing increased infiltration to the AD brain. APOE4 female IL-17+ neutrophils upregulated the immunosuppressive cytokines IL-10 and TGFb, and immune checkpoints including LAG-3 and PD-1, associated with accelerated immune aging. Deletion of APOE4 in neutrophils reduced this immunosuppressive phenotype and restored microglial response to neurodegeneration (MGnD), limiting plaque pathology in AD mice. Mechanistically, IL-17Fupregulated in APOE4 neutrophils interacts with microglial IL-17RA to suppress the induction of MGnD phenotype, and blocking this axis supported cognitive improvement in AD mice. These findings provide a translational basis to target IL-17F in APOE e4 female carriers with cognitive impairment.