The APOE isoforms differentially shape the transcriptomic and epigenomic landscapes of human microglia in a xenotransplantation model of Alzheimer’s disease [RNA-seq]
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE271385 | GEO | 2024/07/08
REPOSITORIES: GEO
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Project description:Microglia play a key role in the response to amyloid beta in Alzheimer’s disease (AD). In this context, the major transcriptional response of microglia is the upregulation of APOE, the strongest late-onset AD risk gene. Of its three isoforms, APOE2 is thought to be protective, while APOE4 increases AD risk. We hypothesised that the isoforms functionally alter microglia by shaping their transcriptomic and chromatin landscapes. We used ATAC- and ATAC-sequencing to profile gene expression and chromatin accessibility of human microglia isolated from a xenotransplantation model of AD. We identified widespread transcriptomic and epigenomic differences which are dependent on APOE genotype, and are corroborated across the profiling assays.
2024-07-08 | GSE271384 | GEO
Project description:Apolipoprotein E (APOE) is a strong genetic risk factor for late-onset Alzheimer’s disease (AD) with APOE4 increasing and APOE2 decreasing risk relative to APOE3. In the P301S mouse model of tauopathy, ApoE4 increases tau pathology and neurodegeneration when compared to ApoE3 or the absence of ApoE. However, the role of ApoE isoforms in regulating lipid metabolism in the setting of tauopathy is unknown. Here, by using targeted lipidomics coupled with histological analysis, we demonstrate that in P301S tau mice, ApoE4 strongly promotes glial lipid accumulation along with significant perturbations in cholesterol metabolism and lysosomal function. Increasing lipid efflux in glia via administration of the LXR agonist GW3965 reduces lipid droplet accumulation in primary E4 microglia in vitro and GW3965 or Abca1 overexpression strongly attenuates tau pathology, neurodegeneration, and synapse loss in P301S/ApoE4 mice. By immunostaining, bulk and snRNA sequencing, we demonstrate reductions in reactive astrocytes and microglia as well as significant changes in cholesterol biosynthesis and metabolism in glia of tauopathy mice in response to LXR activation. These data suggest that promoting efflux of glial lipids via Abca1 could serve as a therapeutic approach to ameliorate tau and ApoE4-linked neurodegeneration.
2023-12-08 | GSE242693 | GEO
Project description:Apolipoprotein E (APOE) is a strong genetic risk factor for late-onset Alzheimer’s disease (AD) with APOE4 increasing and APOE2 decreasing risk relative to APOE3. In the P301S mouse model of tauopathy, ApoE4 increases tau pathology and neurodegeneration when compared to ApoE3 or the absence of ApoE. However, the role of ApoE isoforms in regulating lipid metabolism in the setting of tauopathy is unknown. Here, by using targeted lipidomics coupled with histological analysis, we demonstrate that in P301S tau mice, ApoE4 strongly promotes glial lipid accumulation along with significant perturbations in cholesterol metabolism and lysosomal function. Increasing lipid efflux in glia via administration of the LXR agonist GW3965 reduces lipid droplet accumulation in primary E4 microglia in vitro and GW3965 or Abca1 overexpression strongly attenuates tau pathology, neurodegeneration, and synapse loss in P301S/ApoE4 mice. By immunostaining, bulk and snRNA sequencing, we demonstrate reductions in reactive astrocytes and microglia as well as significant changes in cholesterol biosynthesis and metabolism in glia of tauopathy mice in response to LXR activation. These data suggest that promoting efflux of glial lipids via Abca1 could serve as a therapeutic approach to ameliorate tau and ApoE4-linked neurodegeneration.
2023-12-08 | GSE242180 | GEO
Project description:The APOE gene is diversified by three alleles e2, e3, and e4 encoding corresponding apolipoprotein (apo) E isoforms. The e4 allele promotes age-related cognitive decline, risk of Alzheimer’s disease (AD), and the rate of AD dementia progression. ApoE is produced by astrocytes as high-density lipoprotein-like particles and these are internalized by neurons upon binding to neuron-expressed apoE receptors. ApoE isoforms differentially engage neuronal plasticity through poorly understood mechanisms. We examined here the effects of native apoE lipoproteins produced by immortalized astrocytes homozygous for e2, e3, and e4 alleles on the maturation and the transcriptomic profile of primary hippocampal neurons. Control neurons were grown in the presence of conditioned media from Apoe-/- astrocytes. ApoE2 and apoE3 significantly increase the dendritic arbor branching, the combined neurite length, and the total arbor surface of the hippocampal neurons, while apoE4 fails to produce similar effects and even significantly reduces the combined neurite length compared to the control. ApoE lipoproteins show no systemic effect on dendritic spine density, yet apoE2 and apoE3 increase the mature spines fraction, while apoE4 increases the immature spine fraction. This is associated with opposing effects of apoE2 or apoE3 and apoE4 on the expression of NR1 NMDA receptor subunit and PSD95. There are 1,062 genes differentially expressed across neurons cultured in the presence of apoE lipoproteins compared to the control. KEGG enrichment and gene ontology analyses show common for apoE2 and apoE3 activation of genes involved in neurite branching, and synaptic signaling. In contrast, apoE4 cultured neurons show upregulation of genes related to the glycolipid metabolism, which are involved in dendritic spine turnover and those which are usually silent in neurons and are related to cell cycle and DNA repair. In conclusion our work reveals that lipoprotein particles comprised of various apoE isoforms differentially regulate neuronal development through interaction with neuronal transcriptome. ApoE4 produces a functionally distinct transcriptomic profile, which is associated with attenuated neuronal development. Differential regulation of neuronal transcriptome by apoE isoforms is a newly identified biological mechanism, which has both implication in the development and aging of the CNS.
2022-05-10 | GSE193162 | GEO
Project description:We aim to investigate the interaction between two of the major genetic risk factors for AD: inheritance of APOEε4 and deficiency of Triggering Receptor Expressed on Myeloid cells 2 (TREM2). Trem2 deletion worsened memory in AD model mice but not in their WT littermates. Interestingly, the lack Trem2 resulted in a significantly less microglia around amyloid plaques in APP mice expressing both APOE isoforms but had no impact on amyloid load. Gene expression analysis identified as Trem2 signature a cluster of highly connected immune response genes, commonly downregulated as a result of Trem2 deletion in all experimental groups, such as Clec7a, Itgax, Cts7, Mpeg1, Csf1r, Cx3cr1, Pik3cg and Spi1/PU.1. In vitro experiments with primary microglia demonstrated a decrease of Aβ phagocytosis in APOE4 versus APOE3 microglia a difference that was augmented by the absence of Trem2. Our data demonstrate that the lack of Trem2 differentially impact the phenotype and brain transcriptome of APP mice expressing human APOE isoforms probably reflecting the difference between APOE isoforms to transport lipids that can affect APOE receptor-binding properties.
2020-07-09 | GSE144125 | GEO
Project description:The strongest risk factors for Alzheimer’s disease (AD) include the 4 allele of apolipoprotein E (APOE), the R47H variant of triggering receptor expressed on myeloid cells 2 (TREM2), and female sex. Here, we combine APOE4 and TREM2R47H (R47H) in female P301S tauopathy mice to identify the pathways activated when AD risk is the strongest, thereby highlighting detrimental disease mechanisms. We find that the R47H variant induces neurodegeneration in 9- to- 10-month-old female APOE4 tauopathy mice. The combination of APOE4 and R47H (APOE4-R47H) worsened hyperphosphorylated tau pathology in the frontal cortex and amplified tauopathy-induced cell-autonomous microglial cGAS-STING signaling and downstream interferon response. APOE4-R47H microglia displayed cGAS- and BAX-dependent upregulation of senescence, showing association between neurotoxic signatures and implicating mitochondrial permeabilization in pathogenesis. By uncovering pathways enhanced by the strongest AD risk factors, our study points to cGAS-STING signaling and associated microglial senescence as potential drivers of AD risk.
2024-08-22 | PXD053544 | Pride
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.
2024-06-04 | GSE262632 | GEO
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.
2024-06-04 | GSE260461 | GEO
Project description:In addition to tau and Aβ pathologies, inflammation plays an important role in Alzheimer's disease (AD). Variants in APOE and TREM2 increase AD risk. ApoE4 exacerbates tau-linked neurodegeneration and inflammation in P301S tau mice and removal of microglia blocks tau-dependent neurodegeneration. Microglia adopt a heterogeneous population of transcriptomic states in response to pathology, at least some of which are dependent on TREM2. Previously, we reported that knockout (KO) of TREM2 attenuated neurodegeneration in P301S mice that express mouse Apoe. Because of the possible common pathway of ApoE and TREM2 in AD, we tested whether TREM2 KO (T2KO) would block neurodegeneration in P301S Tau mice expressing ApoE4 (TE4), similar to that observed with microglial depletion. Surprisingly, we observed exacerbated neurodegeneration and tau pathology in TE4-T2KO versus TE4 mice, despite decreased TREM2-dependent microgliosis. Our results suggest that tau pathology-dependent microgliosis, that is, TREM2-independent microgliosis, facilitates tau-mediated neurodegeneration in the presence of ApoE4.
2022-11-30 | GSE206368 | GEO
Project description:The apolipoprotein E4 (APOE4) allele is associated with an increased risk of Alzheimer’s disease and a decreased risk of glaucoma, but the underlying mechanisms remain poorly understood. Here we find that in two mouse glaucoma models and in human glaucomatous retinas, microglia transition to a neurodegenerative (MGnD) phenotype characterized by upregulation of Apoe and Lgals3 (Galectin-3). Mice in which Apoe was targeted in microglia or carrying the human APOE4 allele were protected from retinal ganglion cell (RGC) loss despite elevated intraocular pressure (IOP). Similar to Apoe–/– retinal microglia, APOE4 microglia did not upregulate MGnD genes, including Lgals3, following IOP elevation. Genetic and pharmacologic targeting of Galectin-3 ameliorated RGC degeneration, and Galectin-3 expression was attenuated in human APOE4 glaucoma samples. These results demonstrate that impaired activation of APOE4 microglia is protective in glaucoma, and that the APOE-Galectin-3 signaling pathway can be targeted to treat this blinding disease.
2022-08-16 | GSE192509 | GEO