Project description:Following all types of neurological injury, resident macrophages are activated locally, and blood-derived macrophages are recruited. Distinguishing the role of resident and blood-derived macrophages is complicated by the difficulty in distinguishing between these cell types because they mostly express the same molecular markers in a diseased state. To begin to understand the complexity of functions of resident and blood-derived macrophages following acute injury in the central nervous system (CNS) we ablated microglia, but not infiltrating macrophages, to determine their contribution following lysolecithin-induced demyelination .
Project description:Microglia, brain resident macrophages, require instruction from the central nervous system microenvironment to maintain their identity, morphology, and to regulate inflammatory responses. We investigated the heterogeneity of response of microglia to the presence of neurons and astrocytes by performing single-cell sequencing of microglia in both monoculture, and in coculture with neurons and astrocytes.
Project description:Microglia represent the resident immune cells of the central nervous system. However, blood-borne monocytic cells are also able to invade the ischemic brain. In this study, we aim to characterize similarities and differences between these two cell populations using gene expression profiling.
Project description:Microglia are the resident macrophages of the central nervous system (CNS). Gene profiling identified the transcriptional regulator Sall1 as a microglia signature gene. Given the high expression of Sall1 in microglia, we sought to identify its function in vivo. The Sall1CreER allele has been targeted into the Sall1 locus, therefore Sall1CreER/fl mice (heterozygous for both alleles) allow inducible ablation of Sall1 expression in microglia after tamoxifen treatment. We performed RNA-seq to examine gene expression profiles of microglia sorted from tamoxifen treated adult Sall1CreER/fl mice and Sall1fl/fl control littermates. Microglia were obtained with > 98% purity and the absence of Sall1 was confirmed in Sall1CreER/fl microglia. We could show that deletion of Sall1 in microglia in vivo resulted in the conversion of these cells from resting tissue macrophages into inflammatory phagocytes leading to altered neurogenesis and disturbed tissue homeostasis. Similar changes in gene expression profiles were found in Sall1-deficient microglia isolated from tamoxifen-treated Cx3cr1CreERSall1fl/fl mice. In these mice, deletion of Sall1 is targeted to CX3CR1+ myeloid cells including microglia and CNS-associated macrophages but not to any other CNS-resident cells. This indicated that Sall1 transcriptional regulation maintains microglia identity and physiological properties in the CNS.
Project description:In chronic inflammatory diseases of the central nervous system (CNS), immune cells persisting behind the blood-brain barrier are supposed to promulgate local tissue destruction. The drivers of such compartmentalized inflammation remain unclear, but tissue-resident memory T cells (TRM) represent a potentially important cellular player in this process
Project description:In chronic inflammatory diseases of the central nervous system (CNS), immune cells persisting behind the blood-brain barrier are supposed to promulgate local tissue destruction. The drivers of such compartmentalized inflammation remain unclear, but tissue-resident memory T cells (TRM) represent a potentially important cellular player in this process
Project description:Several viruses can infect the mammalian nervous system and induce neurological dysfunction. Adoptive immunotherapy (AI) is an approach that involves administration of antiviral T cells and has shown promise in clinical studies for the treatment of peripheral virus infections in humans such as cytomegalovirus, Epstein-Barr virus, and adenovirus, among others. Clearance of neurotropic infections, on the other hand, is particularly challenging because the central nervous system (CNS) is relatively intolerant of immunopathological reactions. Therefore, it is essential to develop and mechanistically understand therapies that noncytopathically eradicate pathogens from the CNS. Here, we used mice persistently infected from birth with lymphocytic choriomeningitis virus (LCMV) to demonstrate that therapeutic antiviral T cells can completely purge the persistently infected brain without causing blood brain barrier breakdown or tissue damage. Mechanistically, this is accomplished through a tailored release of chemoattractants that recruit antiviral T cells, but few pathogenic innate immune cells such as neutrophils and inflammatory monocytes. Upon arrival, T cells enlisted the support of nearly all brain resident myeloid cells (microglia) by converting them into CD11c+ antigen-presenting cells (APCs) – a cell population also found in the brain of a human immunodeficiency virus infected patient. Two-photon imaging studies revealed that antiviral CD8+ and CD4+ T cells interacted directly with CD11c+ microglia and induced STAT1 signaling, but did not initiate programmed cell death. We propose that noncytopathic CNS viral clearance can be achieved by therapeutic antiviral T cells reliant on restricted chemoattractant production and interactions with apoptosis-resistant microglia. 6 Mouse Microglia-sorted Brain Samples: 3 (-) AI, 3 (+) AI.
Project description:The ubiquitin-proteasome system maintains the functional proteome of the cells by the clearance of damaged, misfolded, old and/or unneeded proteins. This is particularly important in the brain where protein accumulation has a hallmark of many neurodegenerative diseases that drives neuroinflammation. Microglia are the resident immune cells of the central nervous system and play a major role in the regulation of brain homeostasis via constitutive expression of standard proteasomes and immunoproteasomes (IP). Nevertheless, the impact of IP function on the innate immunity of CNS is not well described. Here, we analyzed ubiquitylated proteins in IP deficient microglia upon enrichment and under different conditions to identify the proteins preferentially degraded by the IP and to investigate the impact of the accumulation of these proteins on microglia function.
Project description:Microglia are resident myeloid cells of the central nervous system (CNS). Recently, single-cell RNA sequencing (scRNAseq) has enabled description of a disease-associated subtype of microglia (DAM) with a role in neurodegeneration and demyelination. In this study we use scRNAseq to investigate the temporal dynamics of immune cells harvested from the epicenter of traumatic spinal cord injury (SCI). As a consequence of SCI, homeostatic microglia undergo permanent transcriptional re-programming into a subtype of microglia with striking similarities to previoysly reported DAM as well as a distinct microglial state found during development. Using a microglia depletion model we showed that DAM in SCI are derived from homeostatic microglia and strongly enhance recovery of hind limb locomotor function following injury.
Project description:Microglia are important immune cells in the central nervous system (CNS). Dysfunctions of gene-deficient microglia contribute to the development and progression of multiple CNS diseases. Microglia replacement by nonself cells has been proposed to treat microglia associated disorders. However, most of attempts are failed due to low replacement efficiencies, such as with the traditional bone marrow transplantation approach. In this study, we develop three efficient strategies for microglia replacement: microglia replacement by bone marrow transplantation (mrBMT), microglia replacement by peripheral blood (mrPB) and microglia replacement by microglia transplantation (mrMT). mrBMT and mrPB allow microglia-like cells to efficiently replace resident microglia in the whole CNS. On the other hand, mrMT achieves microglia replacement in brain regions of interest. In summary, the present study offers effective tactics for microglia replacement with diverse application scenarios, which potentially opens up a window on treating microglia-associated CNS disorders.