The VCAM1–ApoE pathway directs microglial chemotaxis and alleviates Alzheimer’s disease pathology
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE208006 | GEO | 2023/07/18
REPOSITORIES: GEO
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Project description:Impairment of microglial clearance activity contributes to beta-amyloid (Aβ) pathology in Alzheimer disease (AD). While the transcriptome profile of microglia directs microglial functions, how the microglial transcriptome can be regulated to alleviate AD pathology is largely unknown. Here, we show that injection of interleukin (IL)-33 in an AD transgenic mouse model ameliorates Aβ pathology by reprogramming microglial epigenetic and transcriptomic profiles to induce a microglial subpopulation with enhanced phagocytic activity. These IL-33–responsive microglia (IL-33RM) express distinct transcriptome signature, highlighted by major histocompatibility complex class II genes, and restored homeostatic signature genes. IL-33–induced remodeling of chromatin accessibility and PU.1 transcription factor binding at the signature genes of IL-33RM control their transcriptome reprogramming. Specifically, disrupting PU.1–DNA interaction abolishes the microglial state transition and Aβ clearance induced by IL-33. Thus, we define a PU.1-dependent transcriptional pathway that drives the IL-33–induced functional state transition of microglia, resulting in enhanced Aβ clearance.
2020-05-01 | GSE147495 | 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
Project description:Amyloid-beta (Aβ) deposition is an initiating factor in Alzheimer´s disease (AD). Microglia are the brain immune cells that surround and phagocytose Aβ, but their phagocytic capacity declines in AD. This is in agreement with studies that associate AD risk loci with genes regulating phagocytic function. Immunotherapies are currently pursued as therapeutic strategies against AD and there are increased efforts to understand the role of the immune system in ameliorating AD pathology. Here, we evaluated the effect of the Aβ targeting ACI-24 vaccine in preventing the AD pathology in an amyloidosis mouse model. ACI-24 vaccination elicited a robust and sustained antibody response in APPPS1 mice with an accompanying reduction of Aβ plaque load, amyloid plaque-associated ApoE and dystrophic neurites as compared to non-vaccinated controls. Furthermore, plaque-associated microglia had the tendency to be more activated post vaccination. The lower Aβ plaque load triggered by vaccination with ACI-24 was in concordance with the bulk transcriptomic analysis that revealed a reduction in the expression of several disease-associated microglial signatures. Accordingly, plaque-distant microglia displayed a more ramified morphology, supporting beneficial effects of the vaccination on bulk microglial phenotypes. Our study demonstrates that administration of the Aβ targeting vaccine, ACI-24, triggers protective microglial responses that translate into a reduction of AD pathology suggesting its use as a safe and cost effective AD therapeutic intervention.
2023-01-09 | PXD038665 | Pride
Project description:Microglia are innate immune cells of the brain that perform phagocytic and inflammatory functions in disease conditions. Transcriptomic studies of acutely-isolated microglia have provided novel insights into their molecular and functional diversity in homeostatic and neurodegenerative disease states. State-of-the-art mass spectrometric methods can comprehensively characterize proteomic alterations in microglia in neurodegenerative disorders, potentially providing novel functionally-relevant molecular insights that are not provided by transcriptomics. However, proteomic profiling of adult primary microglia in neurodegenerative disease conditions has not been performed. We performed quantitative proteomic analyses of purified CD11b+ acutely-isolated microglia adult mice in normal, acute neuroinflammatory (LPS-treatment) and chronic neurodegenerative states (5xFAD model of Alzheimer’s disease [AD]) using tandem mass tag mass spectrometry. Differential expression analyses were performed to characterize specific microglial proteomic changes in 5xFAD mice and identify overlap with LPS-induced pro-inflammatory changes. Our results were also contrasted with existing proteomic data from wild-type mouse microglia and from existing microglial transcriptomic data from wild-type and 5xFAD mice. Neuropathological validation studies of select proteins were performed in human AD and 5xFAD brains. Of 4,133 proteins identified, 187 microglial proteins were differentially expressed in the 5xFAD mouse model of AD pathology, including proteins with previously known (Apoe, Clu and Htra1) as well as previously unreported relevance to AD biology (Cotl1 and Hexb). Proteins upregulated in 5xFAD microglia shared significant overlap with pro-inflammatory changes observed in LPS-treated mice. Several proteins increased in human AD brain were also upregulated by 5xFAD microglia (Aβ peptide, Apoe, Htra1, Cotl1 and Clu). Cotl1 was identified as a novel microglia-specific marker with increased expression and strong association with AD neuropathology. Apoe protein was also detected within plaque-associated microglia in which Apoe and Aβ were highly co-localized suggesting a role for Apoe in phagocytic clearance of Aβ. We report the first comprehensive comparative proteomic study of adult mouse microglia derived from acute neuroinflammatory and AD models, representing a valuable resource to the neuroscience research community. We highlight shared and unique microglial proteomic changes in acute neuroinflammatory, aging and AD mouse models in addition to identifying novel roles for microglial proteins in human neurodegeneration.
2018-09-18 | PXD009137 | Pride
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:Neuroinflammation is thought to contribute to the pathogenesis of Alzheimer’s disease (AD), yet numerous studies have demonstrated a beneficial role for neuroinflammation in amyloid plaque clearance. We have previously shown that sustained expression of IL-1β in the hippocampus of APP/PS1 mice decreases amyloid plaque burden independent of recruited CCR2+ myeloid cells, suggesting resident microglia as the main phagocytic effectors of IL-1β-induced plaque clearance. To date, however, the mechanisms of IL-1β-induced plaque clearance remain poorly understood. To determine whether IL-1β-induced plaque clearance is due to enhanced microglial phagocytosis of Aβ, APP/PS1 mice induced to express mature human IL-1β in the hippocampus via adenoviral transduction were treated with the Aβ fluorescent probe methoxy-X04 (MX04) and microglial internalization of Aβ was analyzed by flow cytometry and immunohistochemistry. We found that resident microglia (CD45loCD11b+) constituted >70% of the MX04+ cells in both control and IL-1β-treated conditions, and that <10% of MX04+ cells were recruited myeloid cells (CD45hiCD11b+). However, we found that IL-1β treatment did not augment the percentage of MX04+ microglia nor the quantity of Aβ internalized by individual microglia. Instead, we found that IL-1β treatment resulted in a significant increase in the total number of MX04+ microglia in the hippocampus due to IL-1β-induced proliferation. Consistent with these results, transcriptomic analyses revealed very similar gene expression profiles between MX04+ and MX04- microglia, indicating IL-1β does not drive enhanced expression of phagocytosis-related genes. By contrast, IL-1β treatment was associated with large-scale changes in the expression of genes related to proliferation, immune function and inflammation. Together, these studies demonstrate that IL-1β induces microglial proliferation and the expression of genes involved in inflammatory immune functions that may be related to Aβ clearance.
2019-05-01 | GSE113539 | GEO
Project description:Variations in many genes linked to sporadic Alzheimer’s disease (AD), show abundant expression in microglia, however, relationships between these genes remain largely elusive. Here, we establish isogenic human ES-derived microglia-like cell lines (hMGLs) harboring AD variants in CD33, INPP5D, SORL1 and TREM2 loci, and curate a comprehensive atlas comprising ATACseq, ChIPseq, RNAseq and proteomics datasets. AD-like expression signatures are observed in AD mutant SORL1 and TREM2 hMGLs, while integrative multi-omic analysis of combined epigenetic and expression datasets indicates upregulation of APOE as a convergent pathogenic node. We also observe cross-regulatory relationships between SORL1 and TREM2, where SORL1R744X hMGLs induce TREM2 expression to enhance APOE expression. AD-associated SORL1 and TREM2 mutations also impaired hMGL Aβ uptake in an APOE-dependent manner in vitro, and attenuated Aβ uptake/clearance in mouse AD brain xenotransplants. Utilizing this modeling and analysis platform for human microglia, we provide new insight into epistatic interactions in AD genes and demonstrate convergence of microglial AD genes at the APOE locus.
2020-09-01 | GSE153655 | GEO
Project description:Variations in many genes linked to sporadic Alzheimer’s disease (AD), show abundant expression in microglia, however, relationships between these genes remain largely elusive. Here, we establish isogenic human ES-derived microglia-like cell lines (hMGLs) harboring AD variants in CD33, INPP5D, SORL1 and TREM2 loci, and curate a comprehensive atlas comprising ATACseq, ChIPseq, RNAseq and proteomics datasets. AD-like expression signatures are observed in AD mutant SORL1 and TREM2 hMGLs, while integrative multi-omic analysis of combined epigenetic and expression datasets indicates upregulation of APOE as a convergent pathogenic node. We also observe cross-regulatory relationships between SORL1 and TREM2, where SORL1R744X hMGLs induce TREM2 expression to enhance APOE expression. AD-associated SORL1 and TREM2 mutations also impaired hMGL Aβ uptake in an APOE-dependent manner in vitro, and attenuated Aβ uptake/clearance in mouse AD brain xenotransplants. Utilizing this modeling and analysis platform for human microglia, we provide new insight into epistatic interactions in AD genes and demonstrate convergence of microglial AD genes at the APOE locus.
2020-09-01 | GSE153654 | GEO
Project description:Variations in many genes linked to sporadic Alzheimer’s disease (AD), show abundant expression in microglia, however, relationships between these genes remain largely elusive. Here, we establish isogenic human ES-derived microglia-like cell lines (hMGLs) harboring AD variants in CD33, INPP5D, SORL1 and TREM2 loci, and curate a comprehensive atlas comprising ATACseq, ChIPseq, RNAseq and proteomics datasets. AD-like expression signatures are observed in AD mutant SORL1 and TREM2 hMGLs, while integrative multi-omic analysis of combined epigenetic and expression datasets indicates upregulation of APOE as a convergent pathogenic node. We also observe cross-regulatory relationships between SORL1 and TREM2, where SORL1R744X hMGLs induce TREM2 expression to enhance APOE expression. AD-associated SORL1 and TREM2 mutations also impaired hMGL Aβ uptake in an APOE-dependent manner in vitro, and attenuated Aβ uptake/clearance in mouse AD brain xenotransplants. Utilizing this modeling and analysis platform for human microglia, we provide new insight into epistatic interactions in AD genes and demonstrate convergence of microglial AD genes at the APOE locus.
2020-09-01 | GSE153657 | GEO
Project description:Background: ABCA1 has recently been identified as a novel genetic risk factor for Alzheimer’s disease. The major known role of ABCA1 in the brain is to transfer lipids onto lipid poor APOE. Given that APOEε4 is the strongest genetic risk factor for developing late onset Alzheimer’s disease, this recent finding implicates the cholesterol homeostatic pathway in the onset/progression of Alzheimer’s disease. microRNAs (miRs) are small RNA species that negatively regulate expression of their target genes. ABCA1 is regulated by miR-33, and loss of this miR significantly increases protein levels of ABCA1 and increases the lipidation of APOE. However, it is unknown if loss of miR-33 and subsequent increase in ABCA1 protein levels ameliorates amyloid pathology. Methods: We generated miR-33+/+;APP/PS1 and miR-33-/-;APP/PS1 mice to determine changes in amyloid-beta (Aβ) peptides and amyloid plaque formation utilizing biochemical and histological analyses. In addition to amyloid pathology, we assessed if deletion of miR-33 altered the activation of glial cells in the brains of these mice. We utilized in vitro methods to determine if miR-33 alters the phagocytosis of Aβ aggregates. We utilized RNA-sequencing and mass spectrometry to identify the transcriptome and proteome regulation by miR-33 in the context of amyloid pathology. Results: Deletion of miR-33 dramatically reduces insoluble Aβ peptide levels and the deposition of amyloid plaques in APP/PS1 mice. In addition, we identified that astrocyte and microglial activation is markedly decreased in miR-33-/-;APP/PS1 mice through histological analyses. Intriguingly, we show that loss of miR-33 results in amyloid plaques that are more compact, potentially implicating enhanced microglial phagocytosis. We confirm in vitro that loss of miR-33 significantly increases microglial phagocytosis of Aβ aggregates. Our multi-omics analyses reveal that deletion of miR-33 regulates immune response in the context of amyloid pathology. Interestingly, we identified that WNT/Beta-catenin signaling is significantly upregulated in miR-33-/-;APP/PS1 mice. Conclusion: We confirm that the deletion of miR-33 increases APOE lipidation and significantly reduces amyloid pathology as well as glial activation in APP/PS1 mice. Our results agree with previous work identifying APOE lipidation as an important modulator of amyloid pathology. We show, for the first time, that loss of miR-33 increases the phagocytosis of Aβ by microglia. In total, we identify miR-33 as a promising target for the amelioration of amyloid pathology.
2024-09-30 | GSE235179 | GEO