Project description:Microglia are specialized macrophages of the central nervous system (CNS) and first to react to pathogens or injury. Transcriptional profiling significantly contributed to our understanding of microglia functions. In the case of human CNS samples, a postmortem delay (PMD) in tissue access and collection is the potential factor that might affect microglia gene expression profiles. However, the direct analysis of effects of PMD on human microglia transcriptome is challenging due to many confounding factors such as sex, aging, nutrition, lifestyle, medication and medical history. To determine the effects of PMD on the microglia transcriptome. Here, we analyzed mouse microglia, where ante-mortem conditions and post-mortem delay can be tightly controlled. PMD had very limited effect on mouse microglia gene expression, only 50 genes (out of 15,554 detected genes) were differentially expressed between different PMDs.
Project description:Microglia are specialized macrophages of the central nervous system (CNS) and first to react to pathogens or injury. Over the last decade, transcriptional profiling of microglia significantly contributed to our understanding of their functions. In the case of human CNS samples, either potential CNS pathology in the case of surgery samples, or a postmortem delay (PMD) due to the time needed for tissue access and collection, are potential factors that affect gene expression profiles. To determine the effect of PMD on the microglia transcriptome, we first analyzed mouse microglia, where genotype, antemortem conditions and PMD can be controlled. Microglia were isolated from mice after different PMDs (0, 4, 6, 12, and 24?hr) using fluorescence-activated cell sorting (FACS). The number of viable microglia significantly decreased with increasing PMD, but even after a 12?hr PMD, high-quality RNA could be obtained. PMD had very limited effect on mouse microglia gene expression, only 50 genes were differentially expressed between different PMDs. These genes were related to mitochondrial, ribosomal, and protein binding functions. In human microglia transcriptomes we previously generated, 31 of the 50 PMD-associated mouse genes had human homologs, and their relative expression was also affected by PMD. This study provides a set of genes that shows relative expression changes in relation to PMD, both in mouse and human microglia. Although the gene expression changes detected are subtle, these genes need to be accounted for when analyzing microglia transcriptomes generated from samples with variable PMDs.
Project description:Microglia are central players in Alzheimer’s Disease (AD) pathology, but analyzing microglia states in human brain samples is challenging due to genetic diversity, postmortem delay and admixture of pathologies. To circumvent these issues, here we generated 138,577 single cell expression profiles of human stem cell-derived microglia xenotransplanted in the brain of the AppNL-G-F model of amyloid pathology and wild type controls. Xenografted human microglia adopt a disease-associated (DAM) profile similar to that seen in mouse microglia, but display a more pronounced HLA state, likely related to antigen presentation in response to amyloid plaques. The human microglial response also involves a pro-inflammatory cytokine/chemokine CRM response to oligomeric Aβo. Genetic deletion of TREM2 or APOE, as well as APOE polymorphisms and TREM2R47H expression in the transplanted microglia modulate these responses differentially. The expression of other AD risk genes is differentially regulated across the distinct cell states elicited in response to amyloid pathology. Thus, we have identified multiple transcriptomic cell states adopted by human microglia in response to AD-related pathology, which should be taken into account in translational studies.
Project description:There is evidence that microglia interact with infiltrating Th1 and Th17 cells and this interaction results in mutual activation. However, the potential of a distinct cytokine milieu generated by these effector T cell subsets to activate microglia is poorly understood. In this study, we tested the ability of factors secreted by Th1 and Th17 cells to induce microglial activation. Interestingly, we found that only Th1-associated factors had the potential to activate microglia while the Th17-associated factors as well as direct contact of Th17 cells with microglia only had a minimal effect. Further Th1-derived factors triggered a proinflammatory M1-type gene expression profile in microglia Microglia harvested from mixed glial cultures were treated with supernatants from Th1- or Th17 cultures. Microglia cultured in medium was used as controls. At 16h post treatment RNA was isolated from the microglia and probed on Agilent´s murine 4x44k microarrays. RNA isolated from four independent experiments were used for the gene expression profiling. Microglia, Th1, Th17
Project description:Our aim was to identify genes that were differentially expressed in microglia stimulated with Lipopolysaccharide, Luteolin, or both. Affymetrix microarrays were used to analyze RNA samples Experiment Overall Design: RNA from control BV-2 cells, and cells treated for 24h with LPS, Luteolin, or LPS+Luteolin was analyzed with Affymetrix GeneChip Mouse Genome 430 2.0 Arrays. Biological triplicates were analyzed for each condition
Project description:Preparation of primary microglial cultures from postnatal mice is tedious with a low yield, high variability and risk of astrocytic contamination. Microglia derived from embryonic stem cells (ESdM) have been suggested as alternative source, but it is unclear how closely ESdM resemble the molecular phenotype of primary microglia. Here, we performed a whole transcriptome analysis of ESdM in comparison to primary cultured and flow cytometry-sorted microglia and compared the microglial transcriptome to other cell types. Cultured microglia and ESdM were related to sorted microglia, but clearly distinct from other myeloid cell types, T cells, astrocytes and neurons. ESdM and primary cultured microglia showed strong overlap in their transcriptome. Only 144 gene transcripts were differentially expressed between both cell types, mainly derived from immune-related genes with a higher activation status of pro-inflammatory and immune defense genes in primary microglia compared to ESdM. Flow cytometry analysis of cell surface markers CD54, CD74 and CD274 selected from the microarray confirmed the close phenotypic relation between ESdM and primary cultured microglia. Thus, assessment of genome-wide transcriptional regulation demonstrates that microglia are distinct from other macrophage cell types and that mouse pluripotent stem cell-derived microglia are closely related to cultured postnatal microglia. Comparison of different primary neuronal cells with ES-cell derived microglial cells
Project description:Attempts to establish a tissue bank from autopsy samples have led to uncovering of the secrets of many diseases. Here, we examined the length of time that the RNA from postmortem tissues is available for microarray analysis and reported the gene expression profile for up- and down-regulated genes during the postmortem interval (PMI). We extracted RNA from fresh-frozen (FF) and formalin-fixed paraffin-embedded (FFPE) brains and livers of three different groups of mice: 1) mice immediately after death, 2) mice that were stored at room temperature for 3 h after death, and 3) mice that were stored at 4°C for 18 h after death, as this storage resembles the human autopsy process in Japan. Based on the microarray analysis, we selected genes that were altered by >1.3-fold or <0.77-fold and classified these genes using hierarchical cluster analysis following DAVID (database for annotation, visualization, and integrated discovery) gene ontology analysis. These studies revealed that cytoskeleton-related genes were enriched in the set of up-regulated genes, while serine protease inhibitors were enriched in the set of down-regulated genes. Interestingly, although the RNA quality was maintained, up-regulated genes were not validated by quantitative PCR, suggesting that these genes may become fragmented or modified by an unknown mechanism. We extracted RNA from fresh-frozen (FF) brains and livers from mice under three different conditions: 1) mice just after death as a control, 2) mice that were stored at room temperature for 3 h after death, and 3) mice that were stored at 4°C for 18 h after death to resemble the human autopsy process. We also created formalin-fixed paraffin-embedded (FFPE) tissue blocks at the same time using mouse organs obtained under the three conditions described above. We then purified RNA from the FFPE tissue blocks. Furthermore, we performed microarray analysis to examine changes in the gene expression profiles during the postmortem interval in FF samples and to compare ene expression profiles between FF and FFPE samples at three different postmortem times as described for the FF samples.
Project description:Glioblastoma multiforme (GBM) is a highly malignant brain cancer, and microglial cells play a critical role in its progression. Activation of microglia can either promote or inhibit GBM growth depending on the stage of tumour development and on the microenvironment. As current treatments for GBM have limited efficacy, there is an urgent need to develop novel strategies based on nanoplatforms for drug delivery and efficient targeting. This study investigated the microglial response and the therapeutic efficacy of dual cell membrane-coated and doxorubicin-loaded hexagonal boron nitride nanoplatelets, tested on human microglia and GBM cells. The results showed promising therapeutic effects on glioma cells and an M2 microglia polarization, highlighted through proteomic analysis.
Project description:Infiltrating monocyte derived macrophages (MDMs) and resident microglia dominate CNS injury sites. We show that MDMs and microglia can directly communicate to modulate each other’s function. Also, the presence of MDMs in CNS injury suppresses microglia-mediated phagocytosis and inflammation. We suggest that macrophages infiltrating the injured CNS provide a mechanism to control acute and chronic microglia-mediated inflammation, which could otherwise drive damage in a variety of CNS conditions. To understand the global effects of macrophage communication to microglia, we transcriptionally profiled activated adult mouse microglia in the presence or absence of macrophages with and without an inflammatory stiumulus (LPS)