Distinct signature, origin and dynamics of macrophages in the peripheral and central nervous system (single cells)
Ontology highlight
ABSTRACT: We performed ontogenic, transcriptomic and spatial characterization of sciatic nerve Macs (snMacs). Using multiple fate-mapping systems, we show that snMacs do not derive from the early embryonic precursors colonizing the CNS, but originate primarily from late embryonic precursors and get replaced by bone marrow-derived Macs over time. Using single-cell profiling, we identified a tissue-specific core signature of snMacs and found two spatially-separated snMacs: Relmα + Mgl1 + snMacs in the epineurium and Relmα Mgl1 snMacs in the endoneurium. Globally, snMacs lack most core signature genes of microglia, with only the endoneurial subset expressing a restricted number of these genes. Single-cell transcriptomics revealed that in response to injury both snMacs respond differently and that the PNS, in contrast to the CNS, is permissive to prolonged engraftment of monocyte-derived Macs recruited upon injury.
Project description:We performed ontogenic, transcriptomic and spatial characterization of sciatic nerve Macs (snMacs). Using multiple fate-mapping systems, we show that snMacs do not derive from the early embryonic precursors colonizing the CNS, but originate primarily from late embryonic precursors and get replaced by bone marrow-derived Macs over time. Using single-cell profiling, we identified a tissue-specific core signature of snMacs and found two spatially-separated snMacs: Relmα + Mgl1 + snMacs in the epineurium and Relmα Mgl1 snMacs in the endoneurium. Globally, snMacs lack most core signature genes of microglia, with only the endoneurial subset expressing a restricted number of these genes. Single-cell transcriptomics revealed that in response to injury both snMacs respond differently and that the PNS, in contrast to the CNS, is permissive to prolonged engraftment of monocyte-derived Macs recruited upon injury.
Project description:We performed ontogenic, transcriptomic and spatial characterization of sciatic nerve Macs (snMacs). Using multiple fate-mapping systems, we show that snMacs do not derive from the early embryonic precursors colonizing the CNS, but originate primarily from late embryonic precursors and get replaced by bone marrow-derived Macs over time. Using single-cell profiling, we identified a tissue-specific core signature of snMacs and found two spatially-separated snMacs: Relmα + Mgl1 + snMacs in the epineurium and Relmα Mgl1 snMacs in the endoneurium. Globally, snMacs lack most core signature genes of microglia, with only the endoneurial subset expressing a restricted number of these genes. Single-cell transcriptomics revealed that in response to injury both snMacs respond differently and that the PNS, in contrast to the CNS, is permissive to prolonged engraftment of monocyte-derived Macs recruited upon injury.
Project description:Although inflammation appears to play a role in neurolymphomatosis (NL), the mechanisms leading to degeneration in the peripheral nervous system are poorly understood. The purpose of this exploratory study was to identify molecular pathways underlying NL pathogenesis, combining clinical and neuropathological investigation with gene expression (GE) studies. Based on the neuropathic symptoms and signs, NL patients were classified into three forms of neuropathy: chronic symmetrical sensorimotor polyneuropathy (SMPN, n=3), multiple mononeuropathy (MN, n=4) and acute motor-sensory axonal neuropathy (AMSAN, n=1). Predominantly diffuse malignant cells infiltration of epineurium was present in chronic SMPN, whereas endoneurial perivascular cells invasion was observed in MN. In contrast, diffuse endoneurium malignant cells localization occurred in AMSAN. We identified alterations in the expression of 1266 genes, with 115 up-regulated and 1151 down-regulated genes, which were mainly associated with ribosomal proteins (RP) and olfactory receptors (OR) signaling pathways, respectively. Among the top up-regulated genes were actin alpha 1 skeletal muscle (ACTA1) and desmin (DES). Similarly, in NL nerves ACTA1, DES and several RPs were highly expressed, associated with endothelial cells and pericytes abnormalities. Peripheral nerve involvement may be due to conversion towards a more aggressive phenotype, potentially explaining the poor prognosis. The candidate genes reported in this study may be a source of clinical biomarkers for NL.
Project description:Xenopus is uniquely suited for identifying core features of successful CNS axon regeneration, because parts of its CNS (e.g., eye), regenerate axons throughout life, whereas others (e.g., hindbrain) do so only as tadpoles. We performed bisulfite whole genome bisulfite methylation sequencing (WGBS) on juvenile frog eye after optic nerve injury, and on hindbrain samples from tadpole and juvenile frog after spinal cord injury during the peak phase of axon regeneration, to compare tissue-related and injury-induced differences in DNA methylation among them.
Project description:RELMα is a small, secreted protein expressed by T helper type 2 (Th2) cytokine activated “M2” macrophages in helminth infection and allergy. At steady state and in response to Th2 cytokines, RELMα is highly expressed by peritoneal macrophages. We generated RELMα TdTomato (Td) reporter/knockout (RΕLMαTd/Td) mice. RELMαTd/Td mice had increased IL-4 induced peritoneal macrophage responses and splenomegaly compared to RELMα+/+ mice. Nanostring data indicated that RELMαTd/Td peritoneal macrophages were more proliferative and activated than RELMα+/+ macrophages, with increased genes associated with T cell response, growth factor and cytokine signaling, but decreased genes associated with differentiation and maintenance of myeloid cells.This studies identify a new RELMα regulatory pathway whereby RELMα-expressing macrophages directly sustain Treg proliferation to limit Th2 inflammatory responses.
Project description:Xenopus is uniquely suited for addressing the question of whether a core gene expression program for successful CNS axon regeneration exists, because parts of its CNS (e.g., eye), regenerate axons throughout life, whereas others (e.g., hindbrain) do so only as tadpoles. We performed RNA-Seq after optic nerve and spinal cord injury to identify trauma-induced genes shared between two regenerative CNS regions, but not shared with a non-regenerative one. We provide these data as a resource for new avenues of investigation into the molecular basis of tissue regeneration.
Project description:Xenopus is uniquely suited for identifying core features of successful CNS axon regeneration, because parts of its CNS (e.g., eye), regenerate axons throughout life, whereas others (e.g., hindbrain) do so only as tadpoles. To aid in the interpretation of bisulfite whole genome methylation sequencing (WGBS) on juvenile frog eye after optic nerve injury, and on hindbrain samples from tadpole and juvenile frog after spinal cord injury during the peak phase of axon regeneration, we performed ChIP-seq for histone modifications associated with active gene expression (H3K4me3 & H3K27ac) and repressed gene expression (H3K27me3 & H3K9me3) on these same tissues, as well as DNA-immunoprecipitation sequencing (DIP seq) for 5-hydroxymethyl cytosine (5hmC) on eye samples during optic nerve regeneration.
Project description:The RELMα+ macrophage phenotype associates with the presence of anti-inflammatory macrophages and work in other model systems has demonstrated that the balance of pro-inflammatory and anti-inflammatory macrophages is critically important in enabling the resolution of inflammation. Moreover, in the context of type 2 immunity, RELMα+ anti-inflammatory macrophages are associated with the activation of macrophages via the IL4Ra. Despite a breadth of inflammatory pathologies associated with the large intestine, including those that accompany parasitic infection, it is not known about how large intestinal macrophages are activated towards an anti-inflammatory phenotype.
Project description:Appropriate lung repair responses are essential to restore functional integrity and prevent severe disease phenotypes after injury. While macrophages are thought to contribute to repair, whether distinct subsets occupy particular niches and assume dedicated tasks to mediate host recovery post- injury remains unknown. Using an in vivo model of influenza A virus (IAV) infection in combination with single-cell and spatial transcriptomic analyses, bone marrow chimeras and monocyte fate-mapping, we found the transitional appearance of Ccr2-dependent monocyte-derived Ly6G+ macrophages (Ly6G Macs) after viral clearance. Ly6G Macs inhabited the alveolar spaces of regenerating perilesional areas, exhibited a unique ultrastructural morphology as well as a high metabolic potential. Using in vivo gene targeting and ex vivo wound healing assays, we found that Ly6G Macs could limit disease severity and promote alveolar regeneration via interleukin-4 receptor- and arginase-1-dependent mechanisms acting on type 2 alveolar epithelial cells. We also found evidence that similar macrophages existed in other models of lung injury and in the airways of virally-infected humans. Our study thus identifies perilesional alveolar Ly6G Macs as a spatially-restricted short-lived macrophage subset engaging a crosstalk with type 2 alveolar epithelial cells to promote alveolar regeneration and recovery post-injury, thus representing an attractive therapeutic target.
Project description:Appropriate lung repair responses are essential to restore functional integrity and prevent severe disease phenotypes after injury. While macrophages are thought to contribute to repair, whether distinct subsets occupy particular niches and assume dedicated tasks to mediate host recovery post- injury remains unknown. Using an in vivo model of influenza A virus (IAV) infection in combination with single-cell and spatial transcriptomic analyses, bone marrow chimeras and monocyte fate-mapping, we found the transitional appearance of Ccr2-dependent monocyte-derived Ly6G+ macrophages (Ly6G Macs) after viral clearance. Ly6G Macs inhabited the alveolar spaces of regenerating perilesional areas, exhibited a unique ultrastructural morphology as well as a high metabolic potential. Using in vivo gene targeting and ex vivo wound healing assays, we found that Ly6G Macs could limit disease severity and promote alveolar regeneration via interleukin-4 receptor- and arginase-1-dependent mechanisms acting on type 2 alveolar epithelial cells. We also found evidence that similar macrophages existed in other models of lung injury and in the airways of virally-infected humans. Our study thus identifies perilesional alveolar Ly6G Macs as a spatially-restricted short-lived macrophage subset engaging a crosstalk with type 2 alveolar epithelial cells to promote alveolar regeneration and recovery post-injury, thus representing an attractive therapeutic target.