APOE genotype or brain amyloid alters the plasma proteome in elderly subjects without dementia
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ABSTRACT:
PROVIDER: PRJNA1150594 | ENA |
REPOSITORIES: ENA
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Project description:Recent work has bolstered the possibility that peripheral changes may be relevant to Alzheimer’s disease pathogenesis in the brain. While age-associated blood-borne proteins have been targeted to restore function to the aged brain, it remains unclear whether other dysfunctional systemic states can be exploited for similar benefits. Here we investigate whether APOE allelic variation or presence of brain amyloid are associated with plasma proteomic changes and the molecular processes associated with these changes. Using the SOMAscan assay, we measured 1,305 plasma proteins from 53 homozygous, APOE3 and APOE4 subjects without dementia. We investigated the relationship of either the APOE-ε4 allele or amyloid positivity with plasma proteome changes by linear mixed effects modeling and ontology-based pathway and module trait correlation analyses. APOE4 is associated with plasma protein differences linked to atherosclerosis, tyrosine kinase activity, cholesterol transport, extracellular matrix, and synaptogenesis pathways. Independent of APOE4, we found that subjects likely harboring brain amyloid exhibit plasma proteome signatures associated with AD-linked pathways, including neurovascular dysfunction. Our results indicate that APOE4 status or presence of brain amyloid are associated with plasma proteomic shifts prior to the onset of symptoms, suggesting that systemic pathways in certain risk contexts may be plausible targets for disease modification.
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2023-12-29 | GSE239974 | GEO
Project description:Degeneration of synapses in Alzheimer’s disease (AD) strongly correlates with cognitive decline, and synaptic pathology contributes to disease pathophysiology. We recently discovered that the strongest genetic risk factor for sporadic AD, apolipoprotein E epsilon 4 (APOE4), exacerbates synapse loss and synaptic accumulation of oligomeric amyloid beta in human AD brain. To begin to understand the molecular cascades involved in synapse loss in AD and how this is mediated by APOE, and to generate a resource of knowledge of changes in the synaptic proteome in AD, we conducted a proteomic screen and systematic in-silico analysis of synaptoneurosome preparations from temporal and occipital cortices of human AD and control subjects with known APOE gene status. Our analysis identified over 5,500 proteins in human synaptoneurosomes and highlighted disease and APOE-associated changes in multiple molecular pathways including a disruption of cellular and synaptic signalling, glial related protein changes important for neuroinflammatory neuron-glia interactions, and changes in proteins important for mitochondrial function in AD that differ with APOE genotype.
2020-05-26 | PXD013753 | Pride
Project description:Due to an increasingly aging population, the incidence of dementias such as Alzheimer’s disease are steadily rising, with recent estimates predicting >115million dementia sufferers by 2050. The ability to identify early markers in blood, which appear before the onset of clinical symptoms is of considerable interest to allow early intervention, particularly in “high risk” groups such as those with Type 2 Diabetes (T2D). Here we present longitudinal genome-wide DNA methylation data comparing 18 elderly individuals with T2D who developed pre-symptomatic dementia within an 18 month period following baseline assessment to 18 age, sex and education matched controls who maintained normal cognitive function. We identified a highly significant overlap in the effect size of the top-ranked methylation sites at baseline and follow-up, and identified 8 robust loci, some of which have been previously related to neurodegenerative processes, which were consistently differentially methylated prior to symptoms at baseline, and at 18 month follow up, when a diagnosis of pre-symptomatic dementia had been provided. Finally we show a significant overlap in the effect size of the top-ranked methylation sites in converters, only after they develop symptoms of pre-symptomatic dementia, with changes at the same loci in blood samples from patients with clinically-diagnosed Alzheimer’s disease.
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Project description:The major genetic risk factor for Alzheimer’s disease (AD), APOE4, accelerates beta-amyloid (Aβ) plaque formation, but whether this is caused by APOE expressed in microglia or astrocytes is debated. We express here the human APOE isoforms in astrocytes in an Apoe-deficient AD mouse model. This is not only sufficient to restore the amyloid plaque pathology but also induces the characteristic transcriptional pathological responses in Apoe-deficient microglia surrounding the plaques. We find that both APOE4 and the protective APOE2 from astrocytes increase fibrillar plaque deposition, but differentially affect soluble Aβ aggregates. Microglia and astrocytes show specific alterations in function of APOE genotype expressed in astrocytes. Our experiments indicate a central role of the astrocytes in APOE mediated amyloid plaque pathology and in the induction of associated microglia responses.
2024-10-04 | GSE252454 | GEO
Project description:Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder that is influenced by genetic and environmental risk factors, such as inheritance of ε4 allele of APOE (APOE4), sex and diet. Here, we examined the effect of high fat diet (HFD) on amyloid pathology and expression profile in brains of AD model mice expressing human APOE isoforms (APP/E3 and APP/E4 mice). APP/E3 and APP/E4 mice were fed HFD or Normal diet for 3 months. We found that HFD significantly increased amyloid plaques in male and female APP/E4, but not in APP/E3 mice. To identify differentially expressed genes and gene-networks correlated to diet, APOE isoform and sex, we performed RNA sequencing and applied Weighted Gene Co-expression Network Analysis. We determined that the immune response network with major hubs Tyrobp/DAP12, Csf1r, Tlr2, C1qc and Laptm5 correlated significantly and positively to the phenotype of female APP/E4-HFD mice. Correspondingly, we found that in female APP/E4-HFD mice, microglia coverage around plaques, particularly of larger size, was significantly reduced. This suggests altered containment of the plaque growth and sex-dependent vulnerability in response to diet. The results of our study show concurrent impact of diet, APOE isoform and sex on the brain transcriptome and AD-like phenotype.
2018-01-13 | GSE109152 | GEO
Project description:DNA methylation changes have been associated to dementia and cognitive decline. However, it is not clear if these changes arise before or during the onset of the pathologies. Here, using Illumina's MethylationEPIC array technology, we have profiled the methylomes of elderly, cognitively healthy individuals which go on to develop dementia or stay cognitively healthy. The subjects are profiled at a pre-diagnosis stage and at 4 year follow-up post-diagnosis.
2022-04-25 | E-MTAB-10600 | biostudies-arrayexpress
Project description:Alzheimer’s disease (AD) is an age-associated neurodegenerative disease characterized by amyloidosis, tauopathy, and activation of microglia, the brain resident innate immune cells. We show that a RiboTag translational profiling approach can bypass biases due to cellular enrichment/cell sorting. In our recent study entitled “Microglial translational profiling reveals a convergent APOE pathway from aging, amyloid, and tau”, we utilized data acquired using this approach in models of amyloidosis, tauopathy, and aging, to reveal a common set of alterations and identified a central APOE-driven network that converged on CCL3 and CCL4 across all conditions. Notably, examination of the aged female dataset demonstrated a significant exacerbation of many of these shared transcripts in this APOE network, revealing a potential mechanism for increased AD susceptibility in females. This study has broad implications for microglial transcriptomic approaches and provides new insights into microglial pathways associated with different pathological aspects of aging and AD.
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Project description:The E4 allele of Apolipoprotein E (APOE) is associated with both metabolic dysfunction and a heightened pro-inflammatory response – two findings that may be intrinsically linked through the concept of immunometabolism. Here, we combined bulk, single-cell, and spatial transcriptomics with cell-specific and spatially resolved metabolic analyses to systematically address the role of APOE across age, neuroinflammation, and AD pathology. RNAseq highlighted immunometabolic changes across the APOE4 glial transcriptome, specifically in subsets of metabolically distinct microglia enriched in the E4 brain during aging or following an inflammatory challenge. E4 microglia display increased Hif1a expression, a disrupted TCA cycle, and are inherently pro-glycolytic, while spatial transcriptomics and MALDI mass spectrometry imaging highlight an E4-specific response to amyloid that is characterized by widespread alterations in lipid metabolism. Taken together, our findings emphasize a central role for APOE in regulating microglial immunometabolism.
2022-09-04 | GSE212323 | GEO
Project description:One of the hallmarks of Alzheimer’s disease is the presence of extracellular diffuse and fibrillar plaques predominantly consisting of the amyloid-β (Aβ) peptide. ApoE influences the deposition of amyloid pathology through affecting the clearance and aggregation of monomeric Aβ in the brain. In addition to influencing Aβ metabolism, increasing evidence suggests that apoE influences microglial function in neurodegenerative diseases. Here, we characterize the impact that apoE has on amyloid pathology and the innate immune response in APPPS1∆E9 and APPPS1-21 transgenic mice. We report that Apoe deficiency reduced fibrillar plaque deposition consistent with previous studies. However, fibrillar plaques in Apoe-deficient mice exhibited a striking reduction in plaque compaction. Hyperspectral fluorescent imaging using luminescent conjugated oligothiophenes identified distinct Aβ morphotypes in Apoe-deficient mice. We also observed a significant reduction in fibrillar plaque-associated microgliosis and activated microglial gene expression in Apoe-deficient mice, along with significant increases in dystrophic neurites around fibrillar plaques. Our results suggest that apoE is critical in stimulating the innate immune response to amyloid pathology.
2018-02-15 | GSE109906 | GEO