RESUMEN
The cytokine transforming growth factor-ß (TGF-ß) regulates the development and homeostasis of several tissue-resident macrophage populations, including microglia. TGF-ß is not critical for microglia survival but is required for the maintenance of the microglia-specific homeostatic gene signature1,2. Under defined host conditions, circulating monocytes can compete for the microglial niche and give rise to long-lived monocyte-derived macrophages residing in the central nervous system (CNS)3-5. Whether monocytes require TGF-ß for colonization of the microglial niche and maintenance of CNS integrity is unknown. We found that abrogation of TGF-ß signaling in CX3CR1+ monocyte-derived macrophages led to rapid onset of a progressive and fatal demyelinating motor disease characterized by myelin-laden giant macrophages throughout the spinal cord. Tgfbr2-deficient macrophages were characterized by high expression of genes encoding proteins involved in antigen presentation, inflammation and phagocytosis. TGF-ß is thus crucial for the functional integration of monocytes into the CNS microenvironment.
Asunto(s)
Encéfalo/inmunología , Enfermedades Desmielinizantes/inmunología , Macrófagos/patología , Médula Espinal/inmunología , Factor de Crecimiento Transformador beta/inmunología , Animales , Encéfalo/metabolismo , Encéfalo/patología , Enfermedades Desmielinizantes/metabolismo , Enfermedades Desmielinizantes/patología , Macrófagos/inmunología , Macrófagos/metabolismo , Ratones , Transducción de Señal , Médula Espinal/metabolismo , Médula Espinal/patología , Factor de Crecimiento Transformador beta/metabolismoRESUMEN
Microglia are implicated in the pathophysiology of several neurodegenerative disorders, including Alzheimer's disease. While the role of microglia and peripheral macrophages in regulating amyloid beta pathology has been well characterized, the impact of these distinct cell subsets on tau pathology remains poorly understood. We and others have recently demonstrated that monocytes can engraft the brain and give rise to long-lived parenchymal macrophages, even under nonpathological conditions. We undertook the current study to investigate the regulation of tau pathology by microglia and peripheral macrophages using hTau transgenic mice, which do not exhibit microglial activation/pathology or macrophage engraftment. To assess the direct impact of microglia on tau pathology we developed a protocol for long-term microglial depletion in Cx3cr1CreER R26DTA mice and crossed them with hTau mice. We then depleted microglia up to 3 months in both young and old mice, but no net change in forebrain soluble oligomeric tau or total or phosphorylated levels of aggregated tau was recorded. To investigate the consequence of peripherally-derived parenchymal macrophages on tau aggregation we partially repopulated the hTau microglial pool with peripheral macrophages, but this also did not affect levels of tau oligomers or insoluble aggregates. Our study questions the direct involvement of microglia or peripheral macrophages in the development of tau pathology in the hTau model.
Asunto(s)
Enfermedad de Alzheimer/patología , Macrófagos/metabolismo , Microglía/metabolismo , Tauopatías/patología , Proteínas tau/metabolismo , Enfermedad de Alzheimer/metabolismo , Animales , Encéfalo/patología , Modelos Animales de Enfermedad , Ratones Transgénicos , Microglía/patología , Monocitos/metabolismoRESUMEN
We investigated the biotransformation of very small superparamagnetic iron oxide nanoparticles (VSOP) in atherosclerotic LDLR-/- mice. Transmission electron microscopy revealed an uptake of VSOP not only by macrophages but also by endothelial cells in liver, spleen, and atherosclerotic lesions and their accumulation in the lysosomal compartment. Using magnetic particle spectroscopy (MPS), we show that the majority of VSOP's superparamagnetic iron was degraded within 28â¯days. MPS spectrum shape indicated changes in the magnetic properties of VSOP during the biodegradation process. Experiments with primary murine bone marrow derived macrophages, primary murine liver sinusoidal endothelial cells, and primary human aortic endothelial cells demonstrated that loading with VSOP induced a differential response of cellular iron homeostasis mechanisms with increased levels of ferritin and iron transport proteins in macrophages and increased levels of ferritin in endothelial cells.
Asunto(s)
Aterosclerosis/metabolismo , Compuestos Férricos/química , Compuestos Férricos/metabolismo , Nanopartículas de Magnetita/administración & dosificación , Receptores de LDL/fisiología , Animales , Aorta/citología , Aorta/metabolismo , Aterosclerosis/fisiopatología , Capilares/citología , Capilares/metabolismo , Proliferación Celular , Células Cultivadas , Endotelio Vascular/citología , Endotelio Vascular/metabolismo , Ferritinas/metabolismo , Humanos , Macrófagos/citología , Macrófagos/metabolismo , Nanopartículas de Magnetita/química , Masculino , Ratones , Ratones NoqueadosRESUMEN
Intratumoral heterogeneity is a characteristic of glioblastomas that contain an intermixture of cell populations displaying different glioblastoma subtype gene expression signatures. Proportions of these populations change during tumor evolution, but the occurrence and regulation of glioblastoma subtype transition is not well described. To identify regulators of glioblastoma subtypes we utilized a combination of in vitro experiments and in silico analyses, using experimentally generated as well as publicly available data. Through this combined approach SOX2 was identified to confer a proneural glioblastoma subtype gene expression signature. SFRP2 was subsequently identified as a SOX2-antagonist, able to induce a mesenchymal glioblastoma subtype signature. A subset of patient glioblastoma samples with high SFRP2 and low SOX2 expression was particularly enriched with mesenchymal subtype samples. Phenotypically, SFRP2 decreased tumor sphere formation, stemness as assessed by limiting dilution assay, and overall cell proliferation but increased cell motility, whereas SOX2 induced the opposite effects. Furthermore, an SFRP2/non-canonical-WNT/KLF4/PDGFR/phospho-AKT/SOX2 signaling axis was found to be involved in the mesenchymal transition. Analysis of human tumor tissue spatial gene expression patterns showed distinct expression of SFRP2- and SOX2-correlated genes in vascular and cellular areas, respectively. Finally, conditioned media from SFRP2 overexpressing cells increased CD206 on macrophages. Together, these findings present SFRP2 as a SOX2-antagonist with the capacity to induce a mesenchymal subtype transition in glioma cells located in vascular tumor areas, highlighting its role in glioblastoma tumor evolution and intratumoral heterogeneity.
Asunto(s)
Transición Epitelial-Mesenquimal/genética , Regulación Neoplásica de la Expresión Génica , Glioblastoma/etiología , Glioblastoma/metabolismo , Proteínas de la Membrana/genética , Factores de Transcripción SOXB1/genética , Proteínas Portadoras , Línea Celular Tumoral , Perfilación de la Expresión Génica , Glioblastoma/patología , Humanos , Factor 4 Similar a Kruppel/metabolismo , Macrófagos/inmunología , Macrófagos/metabolismo , Macrófagos/patología , Proteínas de la Membrana/metabolismo , Especificidad de Órganos , Unión Proteica , Proteínas Proto-Oncogénicas c-akt/metabolismo , Receptores del Factor de Crecimiento Derivado de Plaquetas/metabolismo , Factores de Transcripción SOXB1/metabolismo , Transducción de SeñalRESUMEN
Circulating monocytes can compete for virtually any tissue macrophage niche and become long-lived replacements that are phenotypically indistinguishable from their embryonic counterparts. As the factors regulating this process are incompletely understood, we studied niche competition in the brain by depleting microglia with >95% efficiency using Cx3cr1CreER/+R26DTA/+ mice and monitored long-term repopulation. Here we show that the microglial niche is repopulated within weeks by a combination of local proliferation of CX3CR1+F4/80lowClec12a- microglia and infiltration of CX3CR1+F4/80hiClec12a+ macrophages that arise directly from Ly6Chi monocytes. This colonization is independent of blood brain barrier breakdown, paralleled by vascular activation, and regulated by type I interferon. Ly6Chi monocytes upregulate microglia gene expression and adopt microglia DNA methylation signatures, but retain a distinct gene signature from proliferating microglia, displaying altered surface marker expression, phagocytic capacity and cytokine production. Our results demonstrate that monocytes are imprinted by the CNS microenvironment but remain transcriptionally, epigenetically and functionally distinct.
Asunto(s)
Encéfalo/inmunología , Linaje de la Célula/inmunología , Regulación de la Expresión Génica/inmunología , Microglía/inmunología , Monocitos/inmunología , Traslado Adoptivo , Animales , Antígenos de Diferenciación/genética , Antígenos de Diferenciación/inmunología , Antígenos Ly/genética , Antígenos Ly/inmunología , Proteínas Bacterianas/inmunología , Células de la Médula Ósea/citología , Células de la Médula Ósea/inmunología , Encéfalo/citología , Encéfalo/efectos de la radiación , Receptor 1 de Quimiocinas CX3C/genética , Receptor 1 de Quimiocinas CX3C/inmunología , Linaje de la Célula/efectos de la radiación , Proliferación Celular , Metilación de ADN , Genes Reporteros , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/inmunología , Interferón Tipo I/genética , Interferón Tipo I/inmunología , Lectinas Tipo C/genética , Lectinas Tipo C/inmunología , Proteínas Luminiscentes/inmunología , Macrófagos/citología , Macrófagos/inmunología , Macrófagos/efectos de la radiación , Ratones , Ratones Transgénicos , Microglía/citología , Microglía/efectos de la radiación , Monocitos/citología , Monocitos/efectos de la radiación , Monocitos/trasplante , Fagocitosis , Receptores Mitogénicos/genética , Receptores Mitogénicos/inmunología , Transducción de Señal , Quimera por Trasplante , Irradiación Corporal TotalRESUMEN
While bone marrow-derived Ly6Chi monocytes can infiltrate the central nervous system (CNS) they are developmentally and functionally distinct from resident microglia. Our understanding of the relative importance of these two populations in the distinct processes of pathogenesis and resolution of inflammation during neurodegenerative disorders was limited by a lack of tools to specifically manipulate each cell type. During recent years, the development of experimental cell-specific depletion models has enabled this issue to be addressed. Herein we compare and contrast the different depletion approaches that have been used, focusing on the respective functionalities of microglia and monocyte-derived macrophages in a range of neurodegenerative disease states, and discuss their prospects for immunotherapy.