Project description:Microglia are key regulators of inflammatory response after stroke and brain injury. Here we profiled the microglia transcriptome isolated from a spontaneously hypertensive rat model of focal cerebral ischemia. We identified an extensive and persistent upregulation of anti-inflammatory M2-like patterns after stroke and a mild up-regulation of pro-inflammatory M1-like patterns at later stage. We also found that younger brains showed larger microglial response than middle aged brains. Moreover, beyond the standard M1/M2 dichotomy, a wide spectrum of novel microglial polarization states was activated in response to stroke, particularly the phenotypes related to Tlr2 and dietary fatty acids stimulation.
Project description:Ischemic stroke is a common acute CNS disorder leading to nearly half a million deaths per year in Europe. The high mortality is primarily owed to the limited treatment options of restoring blood flow in a narrow time window of several hours. Furthermore, inflammatory processes in the days and weeks after ischemic stroke contribute to tissue loss and neurological deficits. The key cells that influence and control this inflammatory cascade are microglia, the innate immune cells of the CNS. Microglia can be influenced and activated by e.g. lipopolysaccharide (LPS),a bacterial cell membrane component. It has been previously shown, that repetitive LPS stimuli prior to infarction (termed immunological preconditioning) lead to reduced infarct volumina in mouse models of ischemic stroke. Furthermore, our laboratory has shown, that phosphoinositide-3 kinase gamma mediates microglial functions after LPS-preconditioning. Hence, the aim of this work was to characterize proteomic alterations in microglia with (I) ischemic stroke in general in the tMCAO (transient middle cerebral artery occlusion) mouse model of ischemic stroke, (II) the influence of LPS-preconditioning on microglial proteomic alterations after tMCAO and (III) the role of PI3Ky in the microglial proteomic changes after tMCAO and preconditioning. This was done by a single LPS injection 3 days before tMCAO in wildtype mice and mice with PI3Ky knockout or knockin of the kinase dead form of PI3Ky.
Project description:To detect chromatin loops maintaining genomic interactions among enhancer and promoter regions in microglia after ischemic stroke, we performed H3K27ac HiChIP of FACS-sorted CD45intCD11bint microglia from sham-operated and post-ischemic day 6 mouse brains.
Project description:To investigate time-dependent changes in gene expression in microglia after ischemic stroke, we performed RNA-seq of FACS-sorted microglia from mouse brains at multiple time points after middle cerebral artery occlusion (MCAO).
Project description:Microglia are resident myeloid cells in the central nervous system (CNS) that regulate homeostasis and protect CNS from damage and infection. The phenotype of microglia is critical in regulating the propagation and resolution of inflammatory responses after ischemic stroke. However, little is known of its complexity and heterogeneity in the above context. Here, using single-cell RNA sequencing (scRNA-seq) of over 11,000 cells from the mice ischemic brain tissues, we demonstrated a previously undefined molecular heterogeneity among microglia clusters following ischemic stroke.
Project description:To investigate time-dependent changes in the epigenetic chromatin state in microglia after ischemic stroke, we performed assay for transposase-accessible chromatin with sequencing (ATAC-seq) of microglia from mouse brains at multiple time points after middle cerebral artery occlusion (MCAO).
Project description:Microglia are resident CNS immune cells that are active sensors in healthy brain and versatile effectors under pathological conditions. Cerebral ischemia induces a robust neuroinflammatory response that includes marked changes in the gene expression and phenotypic profile of a variety of endogenous CNS cell types (astrocytes, neurons, microglia) as well as an influx of leukocytic cells (neutrophils, macrophages, T-cells) from the periphery. Many molecules and conditions can trigger a transformation of ârestingâ (or surveying) microglia to an âactivatedâ (alerted/reactive) state. Here we review recent developments in the literature that relate to microglial activation in the experimental setting of in vitro and in vivo ischemia. We also present new data from our own laboratory demonstrating the direct effects of in vitro ischemic conditions on the microglial phenotype and genomic profile. Emphasis is placed on the role of specific molecular signaling systems such as hypoxia inducible factor-1 (HIF-1) and toll-like receptor-4 (TLR4) in regulating the microglial response in this setting. We then review histological and recent novel radiological data that confirms a key role for microglial activation in the setting of ischemic stroke in humans. We discuss recent progress in the pharmacological and molecular targeting of microglia in acute ischemic stroke. Finally, we explore how recent studies on ischemic preconditioning have increased interest in preemptively targeting microglial activation in order to reduce stroke severity. 12 arrays, 4 experimental groups, 3 replicates in each group, CN is control normoxia, CH is control hypoxia, TN is TLR4 knockout normoxia, TH is TLR4 knockout hypoxia.
Project description:To investigate YY1 and ZFP384 binding in microglia and the microglial cell line after ischemic stroke, we performed cleavage under targets and tagmentation (CUT&Tag) analysis using anti-YY1 and anti-ZFP384 antibodies.