Microglial CLEC7A restrains amyloid beta plaque pathology in a mouse model of Alzheimer's disease
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE315139 | GEO | 2025/12/29
REPOSITORIES: GEO
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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:Microglia are necessary for CNS function during development and play roles in aging, Alzheimer’s Disease (AD) and the response to demyelinating injury. Mitochondrial respiratory chain (RC) is necessary for conventional T cell proliferation6 and macrophage-dependent immune responses. However, whether mitochondrial RC is essential for microglia proliferation or function is not known. We conditionally deleted the mitochondrial complex III subunit Rieske Iron-Sulfur Protein (RISP) in the microglia of adult mice to assess the requirement of microglial RC for survival, proliferation, and adult CNS function in vivo. Surprisingly, mitochondrial RC function was not required for survival or proliferation of microglia in vivo. RNA-seq analysis showed that loss of RC function in microglia caused changes in gene expression distinct from aged or disease-associated microglia (DAM). Microglia-specific loss of mitochondrial RC function is not sufficient to induce cognitive decline. Amyloid-β plaque coverage decreased and microglial interaction with Amyloid-β plaques increased in the hippocampus of 5xFAD mice with mitochondrial RC-deficient microglia. Microglia-specific loss of mitochondrial RC function did impair remyelination following an acute, reversible demyelinating event. Thus, mitochondrial respiration in microglia is dispensable for proliferation but is essential to maintain a proper response to CNS demyelinating injury.
2024-06-10 | GSE269239 | GEO
Project description:It was recently revealed that gut microbiota promote amyloid-beta (Aβ) burden in mouse models of Alzheimer’s disease (AD). However, the underlying mechanisms when using either germ-free (GF) housing conditions or treatments with antibiotics (ABX) remained unknown. In this study, we show that GF and ABX-treated 5x familial AD (5xFAD) mice developed attenuated hippocampal Aβ pathology and associated neuronal loss, and thereby delayed disease-related memory deficits. While Ab production remained unaffected in both GF and ABX-treated 5xFAD mice, we noticed in GF 5xFAD mice enhanced microglial Aβ uptake at early stages of the disease compared to ABX-treated 5xFAD mice. Furthermore, RNA-sequencing of hippocampal microglia from SPF, GF and ABX-treated 5xFAD mice revealed distinct microbiota-dependent gene expression profiles associated with phagocytosis and altered microglial activation states. Taken together, we observed that constitutive or induced microbiota modulation in 5xFAD mice differentially controls microglial Aβ clearance mechanisms preventing neurodegeneration and cognitive deficits.
2020-07-15 | GSE154428 | GEO
Project description:Background: In Alzheimer’s disease (AD), microglia surround extracellular plaques and mount a sustained inflammatory response, contributing to the pathogenesis of the disease. Identifying approaches to specifically target plaque-associated microglia (PAMs) without interfering in the homeostatic functions of non-plaque associated microglia would afford a powerful tool and potential therapeutic avenue. Methods: Here, we demonstrated that a systemically administered nanomedicine, hydroxyl dendrimers (HDs), can cross the blood brain barrier and are preferentially taken up by PAMs in a mouse model of AD. As proof of principle, to demonstrate biological effects in PAM function, we treated the 5xFAD mouse model of amyloidosis for 4 weeks via systemic administration (ip, 2x weekly) of HDs conjugated to a colony stimulating factor-1 receptor (CSF1R) inhibitor (D-45113). Results: Treatment resulted in significant reductions in amyloid-beta (Aβ) and a stark reduction in the number of microglia and microglia-plaque association in the subiculum and somatosensory cortex, as well as a downregulation in microglial, inflammatory, and synaptic gene expression compared to vehicle treated 5xFAD mice. Conclusions: This study demonstrates that systemic administration of a dendranib may be utilized to target and modulate PAMs.
2024-05-07 | GSE266470 | GEO
Project description:The adenosine triphosphate–binding cassette transporter A7 (ABCA7) gene is ranked as one of the top susceptibility loci for Alzheimer’s disease (AD). While ABCA7 mediates lipid transport across cellular membranes, ABCA7 loss of function has been shown to exacerbate amyloid-β (Aβ) pathology and compromise microglial function. Our family-based study uncovered an extremely rare ABCA7 p.A696S variant that was substantially segregated with the development of AD in 3 African American families. Using the knockin mouse model, we investigated the effects of ABCA7-A696S substitution on amyloid pathology and brain immune response in 5xFAD transgenic mice. Importantly, our study demonstrated that ABCA7-A696S substitution reduces amyloid plaque–associated microgliosis and increases dystrophic neurites around amyloid deposits compared to control mice. We also found increased X-34–positive amyloid plaque burden in 5xFAD mice with ABCA7-A696S substitution, while there was no evident difference in insoluble Aβ levels between mouse groups. Thus, ABCA7-A696S substitution may disrupt amyloid compaction resulting in aggravated neuritic dystrophy due to insufficient microglia barrier function. In addition, we observed that ABCA7-A696S substitution disturbs the induction of proinflammatory cytokines interleukin 1β and interferon γ in the brains of 5xFAD mice, although some disease-associated microglia gene expression, including Trem2 and Tyrobp, are upregulated. Lipidomics also detected higher total lysophosphatidylethanolamine levels in the brains of 5xFAD mice with ABCA7-A696S substitution than controls. These results suggest that ABCA7-A696S substitution might compromise the adequate innate immune response to amyloid pathology in AD by modulating brain lipid metabolism, providing novel insight into the pathogenic mechanisms mediated by ABCA7.
2025-03-13 | GSE288170 | 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:GFAP and vimentin deficiency alters gene expression in astrocytes and microglia in wild-type mice and changes the transcriptional response of reactive glia in mouse model for Alzheimer's disease. Reactive astrocytes with an increased expression of intermediate filament (IF) proteins Glial Fibrillary Acidic Protein (GFAP) and Vimentin (VIM) surround amyloid plaques in Alzheimer's disease (AD). The functional consequences of this upregulation are unclear. To identify molecular pathways coupled to IF regulation in reactive astrocytes, and to study the interaction with microglia, we examined WT and APPswe/PS1dE9 (AD) mice lacking either GFAP, or both VIM and GFAP, and determined the transcriptome of cortical astrocytes and microglia from 15- to 18-month-old mice. Genes involved in lysosomal degradation (including several cathepsins) and in inflammatory response (including Cxcl5, Tlr6, Tnf, Il1b) exhibited a higher AD-induced increase when GFAP, or VIM and GFAP, were absent. The expression of Aqp4 and Gja1 displayed the same pattern. The downregulation of neuronal support genes in astrocytes from AD mice was absent in GFAP/VIM null mice. In contrast, the absence of IFs did not affect the transcriptional alterations induced by AD in microglia, nor was the cortical plaque load altered. Visualizing astrocyte morphology in GFAP-eGFP mice showed no clear structural differences in GFAP/VIM null mice, but did show diminished interaction of astrocyte processes with plaques. Microglial proliferation increased similarly in all AD groups. In conclusion, absence of GFAP, or both GFAP and VIM, alters AD-induced changes in gene expression profile of astrocytes, showing a compensation of the decrease of neuronal support genes and a trend for a slightly higher inflammatory expression profile. However, this has no consequences for the development of plaque load, microglial proliferation, or microglial activation. 2 cell types from 6 conditions: cortical microglia and cortical astrocytes from 15-18 month old APPswe/PS1dE9 mice compared to wildtype littermates. Biological replicates: microglia from APPswe/PS1dE9, N=7, microglia from WT, N=7, astrocytes from APPswe/PS1dE9, N=4, microglia from WT, N=4
2015-11-04 | E-GEOD-74614 | biostudies-arrayexpress
Project description:The aim of this study is to characterize the underlying molecular mechanisms of the gain-of-function Trem2T96K mutation in Alzheimer’s disease (AD) pathogenesis by using the constitutive Trem2T96K knock-in mouse crossed to the 5xFAD mouse model of AD. By transcriptional single cell sorting, we comprehensively mapped all microglial populations in 8-month-old female 5xFAD;Trem2+/+, 5xFAD;Trem2T96K/+, and 5xFAD;Trem2T96K/T96K mice. Single-cell RNA-seq analysis revealed that Trem2T96K leads to concomitant suppression of the disease-associated microglia (DAM) gene signature and activation of homeostatic (HOM) genes and impairs the transition of HOM microglia into DAM in female 5xFAD mice. Collectively, these results suggest that Trem2T96K leads to reduced microglial immune activation in female 5xFAD mice.
2025-09-17 | GSE307686 | GEO
Project description:Microglia, the innate immune cells of the brain, play a defining role in the progression of Alzheimer’s disease (AD). The microglial response to amyloid plaques can be either neuroprotective or neurotoxic. Here we show that the protective function of microglia is associated with and functionally linked to a transcriptional shift toward lymphoid gene expression. Microglial contact with the plaques induces downregulation of PU.1, a lineage-specifying transcription factor. PU.1 downregulation plays a key role in mitigating the severity of AD, as evidenced by a reduction in neurotoxic microglia activation, preservation of neuronal connections, maintenance of cognitive function, and increased survival in mice with genetically reduced PU.1 expression in microglia. The neuroprotective effect of PU.1 downregulation is linked to the de-repression of lymphoid-specific proteins, particularly CD28—a surface protein critical for T cell activation. Microglia-specific deficiency in CD28, which is expressed exclusively in a small subset of plaque-associated PU.1low microglia, promotes an inflammatory microglial state and associated increase in amyloid plaque load. Our findings suggest that PU.1low lymphoid/CD28-expressing microglia that emerge in response to AD pathology exert a suppressive, anti-inflammatory effect during AD. This novel role of CD28 -and potentially other lymphoid co-stimulatory or co-inhibitory receptor proteins- in governing microglia responses in AD points to possible new immunotherapy approaches for AD treatment.
2025-08-07 | PXD063383 | Pride
Project description:Over the past decade, genetic evidence has demonstrated that microglial dysregulation is likely to play a central role in the development of Alzheimer's disease (AD). As resident immune cells in the brain, microglia become dystrophic and senescent during the chronic progression of AD. To explore whether replenishing the brain with new microglia is beneficial to AD, we employed a CSF1R inhibitor PLX3397 to deplete microglia and induce repopulation after the inhibitor withdrawal in 5xFAD transgenic mice. We observed that microglial repopulation ameliorates AD-associated cognitive deficits, accompanied by elevation of synaptic proteins and hippocampal long-term potentiation (LTP). In addition, microglial morphology is restored after microglial self-renewal, and amyloid pathology is reduced with long-term repopulation but not short-term. Transcriptome analysis showed that repopulating microglia in 5xFAD mice recovers a gene expression profile that is highly similar to microglia from WT mice. Notably, the neurotrophic signaling pathway and hippocampal neurogenesis dysregulated in the AD brain are restored after microglial replenishment. At last, we confirmed that microglial repopulation rescues brain-derived neurotrophic factor (BDNF) expression to contribute to synaptic plasticity. Together, we conclude that microglial self-renewal benefits AD brain by restoring the BDNF neurotrophic signaling pathway. Thus, the proper replenishment of microglia may be an effective and novel therapeutic strategy for ameliorating cognition impairment in AD.
2023-07-24 | GSE223156 | GEO