Project description:Microglial cells are the resident macrophages of the brain. Perivascular macrophages (PVM) are also myeloid resident cells that are located at the interface between blood, CSF and brain in the perivascular space. Due to their strategic location and their ability to sample CSF content, we hypothesized that PVM might play a role in CSF flow. Using different fluorescent tracers injected either into the CSF (influx) or the brain parenchyma (efflux) we assessed their spatio-temporal distribution and found that ablation (using clodronate liposomes) or dysfunction (using genetic tools) of PVM alters CSF dynamics and patterns. Using single cell RNA sequencing, we found that PBMs can be divided in two sub-populations, and that one population of PBMs could interact with vascular smooth muscle cells, which allow arterial pulsations and subsequently CSF flow. Interestingly, aging results in altered PVM phenotype, and reversing this phenotype using macrophage specific grown factors reversed some of aging-associated dysfunctions of CSF flow. In summary, our results identify a new role of PVM in CSF flow and open new avenues for therapeutical applications targeting PVM in neurodegenerative diseases such as Alzheimer’s disease.
Project description:Microglial cells are the resident macrophages of the brain. Perivascular macrophages (PVM) are also myeloid resident cells that are located at the interface between blood, CSF and brain in the perivascular space. Due to their strategic location and their ability to sample CSF content, we hypothesized that PVM might play a role in CSF flow. Using different fluorescent tracers injected either into the CSF (influx) or the brain parenchyma (efflux) we assessed their spatio-temporal distribution and found that ablation (using clodronate liposomes) or dysfunction (using genetic tools) of PVM alters CSF dynamics and patterns. Using single cell RNA sequencing, we found that PBMs can be divided in two sub-populations, and that one population of PBMs could interact with vascular smooth muscle cells, which allow arterial pulsations and subsequently CSF flow. Interestingly, aging results in altered PVM phenotype, and reversing this phenotype using macrophage specific grown factors reversed some of aging-associated dysfunctions of CSF flow. In summary, our results identify a new role of PVM in CSF flow and open new avenues for therapeutical applications targeting PVM in neurodegenerative diseases such as Alzheimer’s disease.
Project description:Microglial cells are the resident macrophages of the brain. Perivascular macrophages (PVM) are also myeloid resident cells that are located at the interface between blood, CSF and brain in the perivascular space. Due to their strategic location and their ability to sample CSF content, we hypothesized that PVM might play a role in CSF flow. Using different fluorescent tracers injected either into the CSF (influx) or the brain parenchyma (efflux) we assessed their spatio-temporal distribution and found that ablation (using clodronate liposomes) or dysfunction (using genetic tools) of PVM alters CSF dynamics and patterns. Using single cell RNA sequencing, we found that PBMs can be divided in two sub-populations, and that one population of PBMs could interact with vascular smooth muscle cells, which allow arterial pulsations and subsequently CSF flow. Interestingly, aging results in altered PVM phenotype, and reversing this phenotype using macrophage specific grown factors reversed some of aging-associated dysfunctions of CSF flow. In summary, our results identify a new role of PVM in CSF flow and open new avenues for therapeutical applications targeting PVM in neurodegenerative diseases such as Alzheimer’s disease.
Project description:Microglial cells are the resident macrophages of the brain. Perivascular macrophages (PVM) are also myeloid resident cells that are located at the interface between blood, CSF and brain in the perivascular space. Due to their strategic location and their ability to sample CSF content, we hypothesized that PVM might play a role in CSF flow. Using different fluorescent tracers injected either into the CSF (influx) or the brain parenchyma (efflux) we assessed their spatio-temporal distribution and found that ablation (using clodronate liposomes) or dysfunction (using genetic tools) of PVM alters CSF dynamics and patterns. Using single cell RNA sequencing, we found that PBMs can be divided in two sub-populations, and that one population of PBMs could interact with vascular smooth muscle cells, which allow arterial pulsations and subsequently CSF flow. Interestingly, aging results in altered PVM phenotype, and reversing this phenotype using macrophage specific grown factors reversed some of aging-associated dysfunctions of CSF flow. In summary, our results identify a new role of PVM in CSF flow and open new avenues for therapeutical applications targeting PVM in neurodegenerative diseases such as Alzheimer’s disease.
Project description:Central nervous system (CNS) macrophages comprise parenchymal microglia and border-associated macrophages (BAMs) residing in the meninges, the choroid plexus and the perivascular spaces. With the exception of choroid plexus macrophages, most CNS macrophages emerge during primitive hematopoiesis in the extra-embryonic yolk sac. What remains unknown however, is whether microglia and BAMs share a developmental program or arise from separate predefined lineages. Here, we identified two phenotypically, transcriptionally and locally distinct brain macrophage populations throughout development, giving rise to microglia and BAMs. Two independent macrophage populations were already present in the yolk sac prior to their seeding of the brain. Using fate-mapping system, we demonstrate that in contrast to microglia, the pool of embryonic BAMs in the choroid plexus and the meninges was gradually replaced by precursors emerging later in embryogenesis. The development of microglia was dependent on TGF-β whereas the genesis and maturation of BAMs occurred independently of this cytokine. Collectively, our data show that developing parenchymal and non-parenchymal brain macrophages are separate entities in terms of ontogeny, gene expression signatures and requirement for TGF-β.