Project description:Expression profiling of distinct central nervous system (CNS) cell populations has been employed to facilitate disease classification and to provide insights into the molecular basis of brain pathology. One important cell type implicated in a wide variety of CNS disease states is the resident brain macrophage (microglia). In these studies, microglia are often isolated from dissociated brain tissue by flow sorting procedures [fluorescence-activated cell sorting (FACS)] or from postnatal glial cultures by mechanic isolation. Given the highly dynamic and state-dependent functions of these cells, the use of FACS or short-term culture methods may not accurately capture the biology of brain microglia. In the current study, we performed RNA-sequencing using Cx3cr1+/GFP labeled microglia isolated from the brainstem of 6-week-old mice to compare the transcriptomes of FACS-sorted versus laser capture microdissection (LCM). While both isolation techniques resulted in a large number of shared (common) transcripts, we identified transcripts unique to FACS-isolated and LCM-captured microglia. In particular, M-bM-^HM-<50% of these LCM-isolated microglial transcripts represented genes typically associated with neurons and glia. While these transcripts clearly localized to microglia using complementary methods, they were not translated into protein. Following the induction of murine experimental autoimmune encephalomyelitis, increased oligodendrocyte and neuronal transcripts were detected in microglia, while only the myelin basic protein oligodendrocyte transcript was increased in microglia after traumatic brain injury. Collectively, these findings have implications for the design and interpretation of microglia transcriptome-based investigations. Wildtype and GFP expressing microglia from mouse brainstems were flow sorted or captured by laser microdissection. Differences between the two isolation methods were verified and further examined in neurodegenerative disease models.
Project description:Expression profiling of distinct central nervous system (CNS) cell populations has been employed to facilitate disease classification and to provide insights into the molecular basis of brain pathology. One important cell type implicated in a wide variety of CNS disease states is the resident brain macrophage (microglia). In these studies, microglia are often isolated from dissociated brain tissue by flow sorting procedures [fluorescence-activated cell sorting (FACS)] or from postnatal glial cultures by mechanic isolation. Given the highly dynamic and state-dependent functions of these cells, the use of FACS or short-term culture methods may not accurately capture the biology of brain microglia. In the current study, we performed RNA-sequencing using Cx3cr1+/GFP labeled microglia isolated from the brainstem of 6-week-old mice to compare the transcriptomes of FACS-sorted versus laser capture microdissection (LCM). While both isolation techniques resulted in a large number of shared (common) transcripts, we identified transcripts unique to FACS-isolated and LCM-captured microglia. In particular, ∼50% of these LCM-isolated microglial transcripts represented genes typically associated with neurons and glia. While these transcripts clearly localized to microglia using complementary methods, they were not translated into protein. Following the induction of murine experimental autoimmune encephalomyelitis, increased oligodendrocyte and neuronal transcripts were detected in microglia, while only the myelin basic protein oligodendrocyte transcript was increased in microglia after traumatic brain injury. Collectively, these findings have implications for the design and interpretation of microglia transcriptome-based investigations.
Project description:Myelin is required for the function of neuronal axons in the central nervous system, yet the mechanisms supporting myelin health are unclear. Although central nervous system macrophages have been implicated, it is unknown which macrophage populations are involved and which aspects of myelin health they influence. Here, we show that resident microglia are critical for the maintenance of myelin health in adulthood in both mouse and human. We demonstrate that whereas microglia are dispensable for developmental myelin ensheathment, they are required for subsequent regulation of myelin growth and associated cognitive function, and for the preservation of myelin integrity by preventing its degeneration. We discovered that loss of myelin health in the absence of microglia is underpinned by the appearance of a myelinating oligodendrocyte subpopulation with altered lipid metabolism, regulated by a disruption of the TGFβ1-TGFβR1 axis. Our findings highlight microglia as promising therapeutic targets for conditions where myelin growth and integrity are dysregulated, such as in ageing and neurodegenerative disease.
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:Multiple sclerosis involves an aberrant autoimmune response and progressive failure of remyelination in the central nervous system. Prevention of neural degeneration and subsequent disability requires remyelination through the generation of new oligodendrocytes, but current treatments exclusively target the immune system. Oligodendrocyte progenitor cells are stem cells in the central nervous system and the principal source of myelinating oligodendrocytes. These cells are abundant in demyelinated regions of patients with multiple sclerosis, yet fail to differentiate, thereby representing a cellular target for pharmacological intervention. To discover therapeutic compounds for enhancing myelination from endogenous oligodendrocyte progenitor cells, we screened a library of bioactive small molecules on mouse pluripotent epiblast stem-cell-derived oligodendrocyte progenitor cells. Here we show seven drugs function at nanomolar doses selectively to enhance the generation of mature oligodendrocytes from progenitor cells in vitro. Two drugs, miconazole and clobetasol, are effective in promoting precocious myelination in organotypic cerebellar slice cultures, and in vivo in early postnatal mouse pups. Systemic delivery of each of the two drugs significantly increases the number of new oligodendrocytes and enhances remyelination in a lysolecithin-induced mouse model of focal demyelination. Administering each of the two drugs at the peak of disease in an experimental autoimmune encephalomyelitis mouse model of chronic progressive multiple sclerosis results in striking reversal of disease severity. Immune response assays show that miconazole functions directly as a remyelinating drug with no effect on the immune system, whereas clobetasol is a potent immunosuppressant as well as a remyelinating agent. Mechanistic studies show that miconazole and clobetasol function in oligodendrocyte progenitor cells through mitogen-activated protein kinase and glucocorticoid receptor signalling, respectively. Furthermore, both drugs enhance the generation of human oligodendrocytes from human oligodendrocyte progenitor cells in vitro. Collectively, our results provide a rationale for testing miconazole and clobetasol, or structurally modified derivatives, to enhance remyelination in patients. RNA sequencing of oligodendrocyte progenitor cells treated with vehicle, miconazole or clobetasol for 0, 2, 6, or 12 hours. Cells were plated 1.5 hours prior to addition of drug.
Project description:Oligodendrocytes are a type of neuroglia that have provide trophic support and insulation to axons in central nervous system. A proper differentiation of oligodendrocyte precursor cells is crucial for central nervous system myelination and development. Such maturation proccess can be induced in vitro by addition of 12-myristate 13-acetate (PMA) jointly to serum deprivation in oligodendrocyte precursor cell cultures. In the present work, we established a reference data set using 2D LC fractionation and ion-mobility enhanced data-independent proteomic analyses of proteins expressed by treated- and nontreated oligodendrocytes. The final dataset beyond all fractions comprised 223,531 ion peptides corresponding to 10,614 proteins groups. Our results can help futher studies using MO3.13 cells as a tool of investigation not only to oligodendrocyte maturation, also to diseases that have oligodendrocytes as key players.
Project description:Failed regeneration of myelin around neuronal axons following central nervous system damage contributes to nerve dysfunction and clinical decline in various neurological conditions, for which there is an unmet therapeutic demand. Here, we show that interaction between glial cells – astrocytes and mature myelin-forming oligodendrocytes – is a critical determinant of remyelination. Using in vivo/ ex vivo/ in vitro rodent models and human brain lesion analyses, we discover that astrocytes support the survival of regenerating oligodendrocytes, via downregulation of the Nrf2 pathway associated with increased astrocytic cholesterol biosynthesis pathway activation. Remyelination fails following sustained astrocytic Nrf2 activation in focally-lesioned mice yet is restored by either cholesterol biosynthesis/efflux stimulation, or Nrf2 inhibition using the existing therapeutic Luteolin. We identify that astrocyte-oligodendrocyte interaction regulates remyelination, and reveal a drug strategy for central nervous system regeneration centred on targeting this interaction.