Project description:Sepsis-associated encephalopathy is a common complication during systemic inflammation. Microglia are key player in this process. For a better understanding we compared hippocampal tissue following sepsis induction of microglia depleted and non-depleted mice. We show an overall reduction of inflammatory response in the hippocampus of microglia depleted animals.
Project description:Chronic stress is associated with anxiety and cognitive impairment. Repeated social defeat (RSD) in mice induces anxiety-like behavior driven by microglia and the recruitment of inflammatory monocytes to the brain. Nonetheless, it is unclear how microglia communicate with other cells to modulate the physiological and behavioral responses to stress. Using single-cell (sc)RNAseq, novel stress-associated microglia were identified in the hippocampus and defined by RNA profiles of cytokine/chemokine signaling, cellular stress, and phagocytosis. Microglia depletion with a CSF1R antagonist (PLX5622) attenuated the stress-associated profile of leukocytes, endothelia, and astrocytes. Furthermore, RSD-induced social withdrawal and cognitive impairment were microglia dependent, but social avoidance was microglia independent. Furthermore, single-nuclei (sn)RNAseq showed robust responses to RSD in hippocampal neurons that were both microglia dependent and independent. Notably, stress-induced CREB, oxytocin, and glutamatergic signaling in neurons were microglia dependent. Collectively, these stress-associated microglia influenced transcriptional profiles in the hippocampus linked to social and cognitive deficits.
Project description:In this study we hypothesize that early life stress perturbs the normal function of microglia in the developing hippocampus and that this effect is responsible for the ability of early life tress to disrupt normal synaptic maturation, myelination, and axonal growth in the developing hippocampus. To test this hypothesis we used the mouse immune panel from NanoString in order to identify immune-related genes whose expression is modified by BDS, a mouse model of early life stress, in microglia isolated from the hippocampus of 14-day old male pups. This project is part of a manuscript that is currently under preparation (Delpech J.C. et al. Early life stress perturbs the maturation of microglia in the developing hippocampus, Brain, Behavior and Immunity, 2016)
Project description:Previous studies have reported that microglia depletion leads to impairment of synapse formation and these cells rapidly repopulate from CNS progenitors. However, the impact of microglia depletion and repopulation on the long-term state of the CNS environment has not been characterized. Here, we found by RNA-seq analysis that acute and synchronous microglia depletion results in a type 1-interferon inflammatory signature in degenerating somatosensory cortex in microglia-depleted mice. Transcriptomic and mass cytometry analysis of repopulated microglia demonstrates an interferon regulatory factor 7-driven activation state. Minocycline and anti-IFNAR1 antibody treatment attenuate the CNS type-1 interferon-driven inflammation and restore microglia homeostasis. Together, we found that acute microglia ablation induces a type-1 interferon activation state of grey matter microglia associated with acute neurodegeneration.
Project description:The purpose of this experiment is to examine the cellular and molecular changes in the microglia and other non-neuron cells in the hippocampus of 7 month old Mr1+/+ and Mr1-/- mice.
Project description:Microglia is dynamically reprogrammed according to the progression of Alzheimer’s disease (AD). However, clinical translation into biomarker development for functional change in microglia has not been achieved. Here, we find the close association of the metabolic reconfiguration of microglia with increased hippocampal glucose uptake, which can be noninvasively estimated by [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET). We found that increased FDG activity in the hippocampus of an AD mouse model depended on microglial uptake. Single-cell RNA-sequencing of the hippocampus showed the changes of glucose metabolism profiles including glucose transporters, glycolysis and oxidative phosphorylation mainly occurred in microglia. A subset of microglia with high glucose transporters with defective glycolysis and oxidative phosphorylation was increased according to disease progression. Furthermore, we also found a positive association between a soluble TREM2 of cerebrospinal fluid, a marker of microglial activation, and hippocampal FDG uptake as a human study. We identified a reconfiguration of microglial glucose metabolism in the hippocampus of AD and suggested a feasible imaging biomarker based on widely used FDG PET to reflect microglial metabolic profiles.
Project description:The APPSwe/PS1dE9 (APP/PS1) ß-amyloidopathy mouse model exhibits extracellular Aß deposition increasing steadily from about 6 months, particularly in the neocortex and hippocampus, with reactive astrogliosis and synapse loss occurring proximal to plaques. We crossed APP/PS1 mice onto genetically modified mice which lack microglia (Csf1r ∆FIRE/∆FIRE) to assess whether Aß plaque deposition and downstream events are altered in brains lacking microglia.
Project description:Recent studies have demonstrated the complex coordination of pro-inflammatory signaling and reactive microglia/macrophage on the formation Müller glial-derived progenitor cells (MGPCs) intheretinas offish, birds and mice.We generated scRNA-seq libraries to identify transcriptional changes in Müller glia (MG) that result from the depletion of microglia from the chick retina. We found significant changes in different networks of genes in MG in normal and damaged retinas when the microglia are ablated. We identified a failure of MG to upregulate Wnt-ligands, Heparin binding epidermal growth factor (HBEGF), Fibroblast growth factor (FGF), retinoic acid receptors and genes related to Notch-signaling. Inhibition of GSK3β, to simulate Wnt-signaling, failed to rescue the deficit in formation of proliferating MGPCs in damaged retinas missing microglia. By comparison, application of HBEGF or FGF2 completely rescued the formation of proliferating MGPCs in microglia-depleted retinas. Similarly, injection of a small molecule inhibitor to Smad3 or agonist to retinoic acid receptors partially rescued the formation of proliferating MGPCs in microglia-depleted damaged retinas. According to scRNA-seq libraries, patterns of expression of ligands, receptors, signal transducers and/or processing enzymes to cell-signaling via HBEGF, FGF, retinoic acid and TGFβ are rapidly and transiently upregulated by MG after neuronal damage, consistent with important roles for these cell-signaling pathways in regulating the formation of MGPCs. We conclude that quiescent and activated microglia have a significant impact upon the transcriptomic profile of MG. We conclude that signals produced by reactive microglia in damaged retinas stimulate MG to upregulate cell signaling through HBEGF, FGF and retinoic acid, and downregulate signaling through TGFβ/Smad3 to promote the reprogramming on MG into proliferating MGPCs.
Project description:We generated a HeLa cell model of mucopolysaccharidosis IIIB (MPSIIIB) by depleting NAGLU. MPSIIIB-associated cell defects were prominent in NAGLU-depleted cells. We explored alterations of metabolic pathways in NAGLU-depleted cells versus non-depleted control cells by performing gene expression profiling. Exon array transcriptome analysis showed 96 transcripts with increased expression level and 38 transcripts with decreased expression level in NAGLU-depleted versus non-depleted cells. Total RNA was extracted from two independent cultures of non-depleted cells and NAGLU-depleted cells. We considered a minimal fold change of 1.5 fold and a corrected P value lower than 0.05.