Dataset Information

VEGF controls microglial phagocytic response to amyloid-β.

ABSTRACT: Microglial cells are well known to be implicated in the pathogenesis of Alzheimer's disease (AD), due to the impaired clearance of amyloid-β (Aβ) protein. In AD, Aβ accumulates in the brain parenchyma as soluble oligomers and protofibrils, and its aggregation process further give rise to amyloid plaques. Compelling evidence now indicate that Aβ oligomers (Aβo) are the most toxic forms responsible for neuronal and synaptic alterations. Recently, we showed that the Vascular Endothelial Growth Factor (VEGF) counteracts Aβo-induced synaptic alterations and that a peptide derived from VEGF is able to inhibit Aβ aggregation process. Moreover, VEGF has been reported to promote microglial chemotaxis to Aβ brain deposits. We therefore investigated whether VEGF could influence microglial phagocytic response to Aβ, using in vitro and ex vivo models of amyloid accumulation. We report here that VEGF increases Aβo phagocytosis by microglial cells and further characterized the molecular basis of the VEGF effect. VEGF is able to control α-secretase activity in microglial cells, resulting in the increased cleavage of the Triggering Receptor Expressed on Myeloid cells 2 (TREM2), a major microglial Aβ receptor. Consistently, the soluble form sTREM2 also increases Aβo phagocytosis by microglial cells. Taken together, these findings propose VEGF as a new regulator of Aβ clearance and suggest its potential role in rescuing compromised microglial function in AD.

SUBMITTER: de Gea P

PROVIDER: S-EPMC10757340 | biostudies-literature | 2023

REPOSITORIES: biostudies-literature

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VEGF controls microglial phagocytic response to amyloid-β.

de Gea Priscille P Benkeder Sarah S Bouvet Pauline P Aimard Mélanie M Chounlamountri Naura N Honnorat Jérôme J Do Le Duy LD Meissirel Claire C

Frontiers in cellular neuroscience 20231215

Microglial cells are well known to be implicated in the pathogenesis of Alzheimer's disease (AD), due to the impaired clearance of amyloid-β (Aβ) protein. In AD, Aβ accumulates in the brain parenchyma as soluble oligomers and protofibrils, and its aggregation process further give rise to amyloid plaques. Compelling evidence now indicate that Aβ oligomers (Aβo) are the most toxic forms responsible for neuronal and synaptic alterations. Recently, we showed that the Vascular Endothelial Growth Fact ...[more]

PMID: 38162003

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Project description:BackgroundMicroglia are the endogenous immune cells of the brain and act as sensors of pathology to maintain brain homeostasis and eliminate potential threats. In Alzheimer's disease (AD), toxic amyloid beta (Aβ) accumulates in the brain and forms stiff plaques. In late-onset AD accounting for 95% of all cases, this is thought to be due to reduced clearance of Aβ. Human genome-wide association studies and animal models suggest that reduced clearance results from aberrant function of microglia. While the impact of neurochemical pathways on microglia had been broadly studied, mechanical receptors regulating microglial functions remain largely unexplored.MethodsHere we showed that a mechanotransduction ion channel, PIEZO1, is expressed and functional in human and mouse microglia. We used a small molecule agonist, Yoda1, to study how activation of PIEZO1 affects AD-related functions in human induced pluripotent stem cell (iPSC)-derived microglia-like cells (iMGL) under controlled laboratory experiments. Cell survival, metabolism, phagocytosis and lysosomal activity were assessed using real-time functional assays. To evaluate the effect of activation of PIEZO1 in vivo, 5-month-old 5xFAD male mice were infused daily with Yoda1 for two weeks through intracranial cannulas. Microglial Iba1 expression and Aβ pathology were quantified with immunohistochemistry and confocal microscopy. Published human and mouse AD datasets were used for in-depth analysis of PIEZO1 gene expression and related pathways in microglial subpopulations.ResultsWe show that PIEZO1 orchestrates Aβ clearance by enhancing microglial survival, phagocytosis, and lysosomal activity. Aβ inhibited PIEZO1-mediated calcium transients, whereas activation of PIEZO1 with a selective agonist, Yoda1, improved microglial phagocytosis resulting in Aβ clearance both in human and mouse models of AD. Moreover, PIEZO1 expression was associated with a unique microglial transcriptional phenotype in AD as indicated by assessment of cellular metabolism, and human and mouse single-cell datasets.ConclusionThese results indicate that the compromised function of microglia in AD could be improved by controlled activation of PIEZO1 channels resulting in alleviated Aβ burden. Pharmacological regulation of these mechanoreceptors in microglia could represent a novel therapeutic paradigm for AD.

Project description:Microglia are specialized immune cells in the brain that eliminate misfolded protein deposits and cellular debris by phagocytosis. In Alzheimers disease, microglia clear the amyloid beta aggregates during disease onset but are unable to phagocytose them from the tissue environment during the late stages of the disease contributing to chronic inflammation. Lipids and metabolites orchestrate critical regulation events within the cell or by their secretion into the cellular microenvironment, yet, the effect of abeta on microglial lipidome and metabolome has not been well characterized till date. In this study, we used Multiple-Reaction Monitoring (MRM)-profiling to evaluate, for the first time, the lipid and metabolite changes in abeta-activated microglia that were isolated from mouse brains over 24 hours. We also developed a new bioinformatics pipeline to identify the statistically significant lipids and metabolites in abeta-treated microglial cells and condition medium that were differentially regulated compared to the vehicle controls. Triacylglycerides and phosphatidylglycerols were the most abundant lipid classes, whereas long-chain free fatty acids with 26 to 30 acyl chain carbon atoms were consistently decreased with abeta-treatment over time. Further, 42 significant metabolites were identified in cells. L-2-aminobutyric acid, hydroxybutyric acid, inosine, alanine, etc. were differentially regulated with abeta treatment suggesting changes in alanine, aspartate and glutamate metabolism, and arginine biosynthesis pathways. Selected metabolites were identified in the microglial conditioned medium, including stearic acid, tryptophan, palmitic acid, etc. that have been shown to affect the phagocytic properties of peripheral macrophages and may also play a role in the microglial phagocytic response. Thus, characterizing the lipidome and metabolome of microglia due to abeta identifies critical molecules involved in their immune response and highlight the molecular mechanisms of phagocytic function as well as dysfunction associated with AD.

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VEGF controls microglial phagocytic response to amyloid-β.

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VEGF controls microglial phagocytic response to amyloid-β.

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