Differential Effects of Partial and Complete Loss of TREM2 on Microglial Injury Response and Tauopathy [RNA-Seq]
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE118628 | GEO | 2018/09/20
REPOSITORIES: GEO
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Project description:Alzheimer's disease (AD), the most common form of dementia, is characterized by the abnormal accumulation of amyloid plaques and hyperphosphorylated tau aggregates, as well as microgliosis. The link between mutations in Triggering Receptor Expressed on Myeloid Cells 2 (TREM2), a microglia-expressed gene, and the increased risk for developing late-onset AD suggests a detrimental role for microglia in disease pathophyioslogy. Hemizygous TREM2 mutations are posited to increase risk for AD through loss-of-function haploinsufficiency. The effects of TREM2 haploinsufficiency on tau pathology and tau-associated deficits have not yet been characterized. Using in vivo imaging, we showed that TREM2 haploinsufficiency, but not complete loss of TREM2, resulted in a striking agedependent impairment in microglia’s response to injury without affecting baseline motility. This TREM2-dependent effect on microglial motility is consistent with transcriptomic alterations in cell motility uncovered with unbiased RNAsequencing analysis. Moreover, TREM2 haploinsufficiency, but not complete loss of TREM2, exacerbated phosphorylated tau pathology in transgenic mice expressing mutant human tau. In addition, TREM2 haploinsufficiency increased tau inclusions and tau-mediated inflammation without further exacerbating neuronal loss. Our findings demonstrate for the first time that TREM2 haploinsufficiency induces deficits in a tauopathy mouse model, supporting the notion that the hemizygous missense variant results in loss-of-function.
2018-09-20 | GSE107293 | GEO
Project description:The hemizygous R47H variant of TREM2, a microglia-specific gene in the brain, increases risk for late-onset Alzheimer’s disease (AD). To understand its pathogenicity, we performed single-nuclei RNA-sequencing of cortical tissue from AD patients with R47H or the common variant (CV)-TREM2 with matched sex, pathology and APOE status. we found that the R47H mutation is associated with cell type- and sex-specific transcriptional changes in human AD, with microglia exhibiting the most robust alterations. R47H-associated microglial subpopulations were characterized by hyperactivation of AKT, one of the signaling pathways downstream of TREM2, and enhanced inflammatory signatures. In tauopathy mouse models that carry one allele of human TREM2 (hTREM2) with either the R47H mutation or CV, the mutation induced spatial memory deficits and exacerbated tau-mediated deficits in female mice. Similar to the human data, the disease-enhancing effects of R47H microglia were associated with robust increases in proinflammatory cytokines, Syk-Akt-signaling, and elevation of a subset of disease-associated microglial signatures identified using single-cell sequencing from isolated microglia. Pharmacological Akt inhibition largely reversed the enhanced inflammatory signatures in R47H microglia treated with tau fibrils. By unraveling the disease-enhancing properties of the R47H mutation in mouse and human, our findings shed light on an immune-linked AD subtype and provide new directions for modulating brain immune responses to treat AD.
2022-07-16 | GSE154578 | GEO
Project description:The hemizygous R47H variant of TREM2, a microglia-specific gene in the brain, increases risk for late-onset Alzheimer’s disease (AD). Using transcriptomic analysis at the single-nuclei level from brain tissue of AD patients with the R47H mutation or the common variant (CV)-TREM2, we found that R47H-associated microglial subpopulations had enhanced inflammatory signatures reminiscent of previously-identified disease-associated microglia (DAM) and hyperactivation of AKT, one of the signaling pathways downstream of TREM2. We established a tauopathy mouse model with heterozygous knock-in of the human TREM2 with R47H mutation or CV, and found that R47H induced and exacerbated tau-mediated spatial memory deficits in female mice. Single-cell transcriptomic analysis of microglia from these mice also revealed transcriptomic changes induced by R47H that had significant overlaps with R47H microglia in human AD brains, including robust increases in proinflammatory cytokines, activation of Akt signaling, and elevation of a subset of disease-associated microglial signatures. Pharmacological Akt inhibition with MK-2206 largely reversed the enhanced inflammatory signatures in primary R47H microglia treated with tau fibrils. Strikingly, in R47H heterozygous tauopathy mice, MK-2206 treatment abolished a tauopathy-dependent microglial subcluster, and rescued tauopathy-induced synapse loss. By uncovering disease-enhancing mechanisms of the R47H mutation conserved in human and mouse, our study supports inhibitors of AKT signaling as a novel microglial modulating strategy to treat AD.
2021-12-06 | GSE140670 | GEO
Project description:The hemizygous R47H variant of TREM2, a microglia-specific gene in the brain, increases risk for late-onset Alzheimer’s disease (AD). Using transcriptomic analysis at the single-nuclei level from brain tissue of AD patients with the R47H mutation or the common variant (CV)-TREM2, we found that R47H-associated microglial subpopulations had enhanced inflammatory signatures reminiscent of previously-identified disease-associated microglia (DAM) and hyperactivation of AKT, one of the signaling pathways downstream of TREM2. We established a tauopathy mouse model with heterozygous knock-in of the human TREM2 with R47H mutation or CV, and found that R47H induced and exacerbated tau-mediated spatial memory deficits in female mice. Single-cell transcriptomic analysis of microglia from these mice also revealed transcriptomic changes induced by R47H that had significant overlaps with R47H microglia in human AD brains, including robust increases in proinflammatory cytokines, activation of Akt signaling, and elevation of a subset of disease-associated microglial signatures. Pharmacological Akt inhibition with MK-2206 largely reversed the enhanced inflammatory signatures in primary R47H microglia treated with tau fibrils. Strikingly, in R47H heterozygous tauopathy mice, MK-2206 treatment abolished a tauopathy-dependent microglial subcluster, and rescued tauopathy-induced synapse loss. By uncovering disease-enhancing mechanisms of the R47H mutation conserved in human and mouse, our study supports inhibitors of AKT signaling as a novel microglial modulating strategy to treat AD.
2021-12-06 | GSE136389 | GEO
Project description:Non-neuronal responses in neurodegenerative disease have received increasing attention as important contributors to disease pathogenesis and progression. Here we utilize single-cell RNA-sequencing to broadly characterize responses of twelve cell types in three different mouse models of Alzheimer’s Disease, capturing the effects of tau-only, amyloid-only, or combined tau- amyloid pathology. We characterize microglia, oligodendrocyte, astrocyte, and T cell responses and compare them across these models. Notably, we identify two distinct transcriptional states for oligodendrocytes induced during disease and determine their spatial distribution. Furthermore, we explore the impact of Trem2 deletion in the context of combined pathology. Trem2 knockout mice exhibit severely blunted microglial responses to combined tau and amyloid pathology, but responses from non-microglial cell types (oligodendrocytes, astrocytes, and T cells) are relatively unchanged. These results delineate core transcriptional states that are accessible in the degenerating brain and how they are influenced by a key Alzheimer’s Disease risk gene, Trem2.
2021-11-12 | GSE160512 | GEO
Project description:We describe in vivo follow-up PET imaging and postmortem findings from an autosomal dominant Alzheimer’s disease (ADAD) PSEN1 E280A carrier who was also homozygous for the APOE3 Christchurch (APOE3ch) variant and was protected against Alzheimer’s symptoms for almost three decades beyond the expected age of onset. We identified a distinct anatomical pattern of tau pathology with atypical accumulation in vivo and unusual postmortem regional distribution characterized by sparing in the frontal cortex and severe pathology in the occipital cortex. The frontal cortex and the hippocampus, less affected than the occipital cortex by tau pathology, contained Related Orphan Receptor B (RORB) positive neurons, homeostatic astrocytes and higher APOE expression. The occipital cortex, the only cortical region showing cerebral amyloid angiopathy (CAA), exhibited a distinctive chronic inflammatory microglial profile and lower APOE expression. Thus, the Christchurch variant impacts the distribution of tau pathology, modulates age at onset, severity, progression, and clinical presentation of ADAD, suggesting possible therapeutic strategies.
2022-08-26 | GSE206744 | GEO
Project description:The hemizygous R47H variant of TREM2, a microglia-specific gene in the brain, increases risk for late-onset Alzheimer’s disease (AD). In this study, we identified a subpopulation of microglia with disease-enhancing proinflammatory signatures associated with the R47H mutation in human AD brains and tauopathy mouse brains. Using transcriptomic analysis at the single-nuclei level from AD patients with the R47H or the common variant (CV)-TREM2 with matched sex, pathology and clinical dementia status, we found that the R47H mutation was associated with cell type- and sex-specific transcriptional changes in human AD brains. Further characterization of microglia revealed that R47H-associated microglial subpopulations had enhanced inflammatory signatures reminiscent of previously-identified disease-associated microglia (DAM) and hyperactivation of AKT, one of the signaling pathways downstream of TREM2. In a newly-generated tauopathy knock-in mouse model expressing one allele of human TREM2 (hTREM2) with either the R47H mutation or CV, R47H induced and exacerbated tau-mediated spatial memory deficits in female mice. Single-cell transcriptomic analysis of microglia from these mice also revealed transcriptomic changes induced by R47H that had significant overlaps with R47H microglia in human AD brains, including robust increases in proinflammatory cytokines, activation of Akt-signaling, and elevation of a subset of disease-associated microglial signatures. Strikingly, pharmacological Akt inhibition largely reversed the enhanced inflammatory signatures induced by R47H in primary microglia treated with tau fibrils as well as rescued the tauopathy-induced synapse loss in R47H heterozygous mice. By unraveling the disease-enhancing properties of the R47H mutation in mouse and human, our findings shed light on an immune-linked AD subtype and provide new directions for modulating microglial immune responses to treat AD.
2021-08-18 | GSE181903 | GEO
Project description:APOE is the strongest genetic risk factor for late-onset Alzheimer’s disease. ApoE exacerbates tau-associated neurodegeneration by driving microglial activation. However, how apoE regulates microglial activation and whether targeting apoE is therapeutically beneficial in tauopathy is unclear. Here we show that overexpressing a low-density lipoprotein receptor (LDLR) transgene in P301S tau transgenic mice markedly reduces brain apoE and ameliorates tau pathology and neurodegeneration. ApoE specifically interacts with a high-molecular-weight tau species, and highly correlates with phospho-tau and insoluble tau levels. Microglial expression of the LDLR transgene reduces intracellular apoE and is associated with less microglial activation. snRNA-seq analysis of apoE-deficient or LDLR-overexpressing brains reveals that apoE deficiency drives microglial catabolism and increases the oligodendrocyte progenitor cell population. LDLR overexpression shares overlapping mechanisms, but uniquely upregulates microglial expression of specific ion channels and neurotransmitter receptors in tauopathy. A subset of disease-associated astrocytes with both neuroprotective and neurotoxic gene signatures is also identified.
2021-02-06 | GSE166261 | 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: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