Project description:Objective: Brain tumors (gliomas) contain large populations of infiltrating macrophages and recruited microglia, which in experimental murine glioma models promote tumor formation and progression. Among the barriers to understanding the contributions of these stromal elements to high-grade glioma (glioblastoma; GBM) biology is the relative paucity of tools to characterize infiltrating macrophages and resident microglia. In this study, we leveraged multiple RNA analysis platforms to identify new monocyte markers relevant to GBM patient outcome. Methods: High-confidence lists of mouse resident microglia- and bone marrow-derived macrophage-specific transcripts were generated using converging RNA-seq and microarray technologies and validated using qRT-PCR and flow cytometry. Expression of select cell surface markers was analyzed in brain-infiltrating macrophages and resident microglia in an induced GBM mouse model, while allogeneic bone marrow transplantation was performed to trace the origins of infiltrating and resident macrophages. Glioma tissue microarrays were examined by immunohistochemistry, and the Gene Expression Omnibus (GEO) database was queried to determine the prognostic value of identified microglia biomarkers in human GBM. Results: We generated a unique catalog of differentially-expressed bone marrow-derived monocyte and resident microglia transcripts, and demonstrated that brain-infiltrating macrophages acquire F11R expression in GBM and following bone-marrow transplantation. Moreover, mononuclear cell F11R expression positively correlates with human high-grade glioma and additionally serves as a biomarker for GBM patient survival, regardless of GBM molecular subtype. Significance: These studies establish F11R as a novel monocyte prognostic marker for GBM critical for defining a subpopulation of stromal cells for future potential therapeutic intervention. Total RNA was isolated from three independently-generated sets of flow sorted bone marrow monocytes (CD11b+ CD45high CD115+ Ly6G- cells) and brainstem microglia (CD11b+ CD45low CD115low Ly6G- cells) for Illumina RNA-Seq, and two additional pools were subsequently generated and submitted for Affymetrix Mouse Exon 1.0ST microarray. Two of the RNA-Seq samples were additionally analyzed by the microarray, for a total of 6 samples (3 monocyte, 3 microglia) in each platform. Data outputs were analyzed by two analysis methods each (RNA-Seq data: ALEXA-Seq and Cufflinks; microarray data: Partek and Aroma). All four lists were merged into a new high-confidence gene list of transcripts that were significantly differentially expressed (DE) in three out of the four analyses. In this dataset, we includeRNA-Seq data obtained from flow sorted mouse bone marrow monocytes and brainstem microglia.

Project description:Objective: Brain tumors (gliomas) contain large populations of infiltrating macrophages and recruited microglia, which in experimental murine glioma models promote tumor formation and progression. Among the barriers to understanding the contributions of these stromal elements to high-grade glioma (glioblastoma; GBM) biology is the relative paucity of tools to characterize infiltrating macrophages and resident microglia. In this study, we leveraged multiple RNA analysis platforms to identify new monocyte markers relevant to GBM patient outcome. Methods: High-confidence lists of mouse resident microglia- and bone marrow-derived macrophage-specific transcripts were generated using converging RNA-seq and microarray technologies and validated using qRT-PCR and flow cytometry. Expression of select cell surface markers was analyzed in brain-infiltrating macrophages and resident microglia in an induced GBM mouse model, while allogeneic bone marrow transplantation was performed to trace the origins of infiltrating and resident macrophages. Glioma tissue microarrays were examined by immunohistochemistry, and the Gene Expression Omnibus (GEO) database was queried to determine the prognostic value of identified microglia biomarkers in human GBM. Results: We generated a unique catalog of differentially-expressed bone marrow-derived monocyte and resident microglia transcripts, and demonstrated that brain-infiltrating macrophages acquire F11R expression in GBM and following bone-marrow transplantation. Moreover, mononuclear cell F11R expression positively correlates with human high-grade glioma and additionally serves as a biomarker for GBM patient survival, regardless of GBM molecular subtype. Significance: These studies establish F11R as a novel monocyte prognostic marker for GBM critical for defining a subpopulation of stromal cells for future potential therapeutic intervention. Total RNA was isolated from three independently-generated sets of flow sorted bone marrow monocytes (CD11b+ CD45high CD115+ Ly6G- cells) and brainstem microglia (CD11b+ CD45low CD115low Ly6G- cells) for Illumina RNA-Seq, and two additional pools were subsequently generated and submitted for Affymetrix Mouse Exon 1.0ST microarray. Two of the RNA-Seq samples were additionally analyzed by the microarray, for a total of 6 samples (3 monocyte, 3 microglia) in each platform. Data outputs were analyzed by two analysis methods each (RNA-Seq data: ALEXA-Seq and Cufflinks; microarray data: Partek and Aroma). All four lists were merged into a new high-confidence gene list of transcripts that were significantly differentially expressed (DE) in three out of the four analyses. In this dataset, we include exon expression data obtained from flow sorted mouse bone marrow monocytes and brainstem microglia.

Project description:Intratumoral microglia and MΦ constitute up to 70% of the tumor mass of high-grade gliomas (HGG) with profound impact on hallmarks of malignancy such as angiogenesis and immunosuppression. The dynamics and functional states of intratumoral myeloid cells during tumor progression and the molecular mechanisms controlling them are poorly understood. Here we define homeostatic and antigen-presenting myeloid cellular states in experimental and human HGG by longitudinal single-cell RNA-sequencing and combined transcriptome and proteome profiling. During glioma progression, myeloid cells gradually shift from a homeostatic to a tumor-associated effector state. We show that these dynamics are under strict control by early changes in resident microglia and the tumor genotype: In gliomas with mutations in isocitrate dehydrogenase (IDH), a disease-defining driver mutation, differentiation of invaded myeloid cells was blocked resulting in an immature, immunosuppressive phenotype. In late-stage IDH-mutant gliomas, monocyte-derived MΦ drive a tolerogenic remodeling of the glioma microenvironment thus preventing T-cell response. We define the molecular mechanism responsible for the tumor genotype-dependent education of infiltrating MΦ to be causally related to an enzymatically enhanced tryptophan catabolism via TDO2, resulting in the production of kynurenine, an endogenous ligand of the aryl hydrocarbon receptor (AHR). TDO2 activation further induces an amino acid starvation response triggering the import of exogenous tryptophan by intratumoral MΦ via LAT1-CD98. We here provide evidence that paracrine R-2-HG and tryptophan are critically involved in the differentiation and activation of monocyte-derived MΦ and that the previously observed altered amino acid metabolism in IDHmut gliomas is also responsible for shaping an immunosuppressive tumor microenvironment through maintenance of this complex metabolic axis. We further show that this regulatory metabolic network is particularly active in infiltrating MΦ because of their distinct expression profile that constitutes an immune subset-specific metabolic vulnerability. Consequently, the immunosuppressive phenotype in IDH-mutant glioma models was reversed by pharmacological inhibition of LAT1-CD98 or AHR. Thus, we provide evidence for a tumor genotype-dependent, dynamic network of resident and recruited intratumoral myeloid cells that shape the immune microenvironment of IDH-mutant HGG through pleiotropic interaction with the tumor metabolome and identify tryptophan metabolism as a viable therapeutic target for the immunotherapy of IDH-mutant tumors.

Project description:Murine BV2 microglia cells were transfected either with siRNA negative control or siRNA against caspase-3 for 48h. Later on some the of the BV2 transfected cells were co-cultured with C6 glioma cells during 6h. We used the SA Biosciences Mouse Wound Healing PCR Array (PAMM-121Z) to quantitate gene expression of relevant genes related to the wound healing process Glioma cells recruit and exploit microglia, resident immune cells of the brain, for their proliferation and invasion capability. The underlying molecular mechanism used by glioma cells to transform microglia into a tumor-supporting phenotype remains elusive. Here, we report that glioma-induced microglia conversion is coupled to a reduction of basal microglial caspase-3 activity, increased S-nitrosylation of mitochondria-associated caspase-3 through inhibition of thioredoxin-2 activity, and demonstrate that caspase-3 inhibition regulates microglial tumor-supporting function. Further, we identified nitric oxide synthase-2 (NOS2) activity originating from the glioma cells as a driving stimulus in the control of microglial caspase-3 activity. Repression of glioma NOS2 expression in vivo led to reduction in both microglia recruitment and tumor expansion, whereas depletion of the microglial caspase-3 gene promoted tumor growth. This study provides evidence that the inhibition of Trx2-mediated denitrosylation of SNO-procaspase-3 is part of the microglial pro-tumoral activation pathway initiated by glioma cancer cells. qPCR gene expression profiling. Three independent experiments of siControl BV2 monoculture, siCaspase3 BV2 monoculture, siControl BV2 cocultured 6h with C6 glioma cells and siCaspase3 BV2 cocultured 6h with C6 glioma cells. Equal amount total RNA from each culture was used for the gene expression analysis. Please note that the raw data for three independent experiments (prior to averaging the data) is provided in the 'Raw_Data_File_with_the_Ct_values_for_3_indep_experiments.txt'.

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Dynamics of glioma-associated microglia and macrophages reveals their divergent roles in the immune response of brain

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