Project description:Background: Pericytes regulate vessel stabilization and function and their loss is associated with diseases such as diabetic retinopathy or cancer. Despite their physiological importance, pericyte function and molecular regulation during angiogenesis remain poorly understood. Methods: To decipher the transcriptomic programs of pericytes during angiogenesis, we crossed the Pdgfrb(BAC)-CreERT2 into the RiboTagflox/flox mice. Pericyte morphological changes were assessed in mural cell-specific R26-mTmG reporter mice, in which low doses of tamoxifen allowed labeling of single cell pericytes at high resolution. To study the role of phosphoinositide 3-kinase (PI3K) signaling in pericyte biology during angiogenesis, we used genetic mouse models which allow selective inactivation of PI3Kα and PI3Kβ isoforms and their negative regulator PTEN (phosphate and tensin homologue deleted on chromosome ten, PTEN) in mural cells. Results: At the onset of angiogenesis, pericytes exhibit molecular traits of cell proliferation and activated PI3K signaling, whereas during vascular remodeling pericytes upregulate genes involved in mature pericyte cell function, together with a remarkable decrease in PI3K signaling. Immature pericytes showed stellate shape and high proliferation, and mature pericytes were quiescent and elongated. Unexpectedly, we demonstrate that the PI3Kβ, but not PI3Kα, regulates pericyte proliferation and maturation during vessel formation. Genetic PI3Kβ inactivation in pericytes triggered early pericyte maturation. Conversely, unleashing PI3K signaling by means of PTEN deletion delayed pericyte maturation. Pericyte maturation was necessary to undergo vessel remodeling during angiogenesis. Conclusions: Our results identify new molecular and morphological traits associated to pericyte maturation and uncover PI3Kβ activity as a checkpoint to ensure appropriate vessel formation. In turn, our results may open new therapeutic opportunities to regulate angiogenesis in pathological processes through the manipulation of pericyte PI3Kβ activity.
Project description:Here, we performed single nuclear RNA-seq (snRNA-seq) of control and Pitx2 deficient cardiac tissue 3 weeks post myocardial infarction. Next, unsupervised graph-based clustering of the combined snRNA-Seq data set mapped to both introns and exons, comprising 7848 cells. Overall, we identified nine transcriptionally distinct clusters representing all the major cardiac cell types, including cardiac fibroblasts (FB), cardiomyocytes (CM), endothelial cells (EC), vascular smooth muscle cells (SMC), macrophages (Mφ), epicardial cells (EpiC), endocardial cells (EndoC), lymphatic endothelial cells (LEC), and mural cells or pericytes (PeC). Moreover, two distinct populations of fibroblasts, designated FB-1 and FB-2, were also identified.
Project description:Purpose: To further understand the beneficial effects of DSCR1 on the lymphatic system of 5XFAD mice, we investigated the transcriptional landscape of meningeal lymphatic endothelial cells (mLECs) by performing RNA sequencing.
Project description:The meningeal lymphatic network—housed within the dural meninges surrounding the brain— is critical for cerebrospinal fluid (CSF) drainage. Through continuous brain interstitial fluid (ISF) mixing with CSF via the glymphatic system, this lymphatic network facilitates the removal of central nervous system (CNS) waste. During aging and in Alzheimer’s disease (AD), attenuated meningeal lymphatic drainage promotes the buildup of toxic misfolded proteins—including amyloid beta—in the CNS. Alleviating this age-related meningeal lymphatic dysfunction represents a promising therapeutic strategy to alleviate AD pathology. However, the mechanisms underlying this lymphatic decline remain elusive. Here we demonstrate that age-related alterations in meningeal immunity contribute to meningeal lymphatic impairment. Single-cell RNA-sequencing of dural lymphatic endothelial cells in aged mice demonstrated a response signature to the cytokine IFNγ, which was elevated in the aged dura due to meningeal T cell accumulation. Chronic elevation of IFNγ in the meninges of young mice via AAV-mediated overexpression altered lymphatic adherans junctions and impaired CSF drainage to deep cervical lymph nodes—comparable to the deficits observed in aged mice. Direct disruption of lymphatic junctions via CSF-delivered VE-Cadherin disrupting antibodies was sufficient to phenocopy impairments in CSF drainage. Therapeutically, IFNγ neutralization in aged mice alleviated age-related impairments in meningeal lymphatic function. These data suggest manipulation of meningeal immunity as a viable therapeutic target to normalize CSF drainage in aged mice and alleviate the pathology in AD mice associated with impaired waste removal.
Project description:The meningeal lymphatic network—housed within the dural meninges surrounding the brain— is critical for cerebrospinal fluid (CSF) drainage. Through continuous brain interstitial fluid (ISF) mixing with CSF via the glymphatic system, this lymphatic network facilitates the removal of central nervous system (CNS) waste. During aging and in Alzheimer’s disease (AD), attenuated meningeal lymphatic drainage promotes the buildup of toxic misfolded proteins—including amyloid beta—in the CNS. Alleviating this age-related meningeal lymphatic dysfunction represents a promising therapeutic strategy to alleviate AD pathology. However, the mechanisms underlying this lymphatic decline remain elusive. Here we demonstrate that age-related alterations in meningeal immunity contribute to meningeal lymphatic impairment. Single-cell RNA-sequencing of dural lymphatic endothelial cells in aged mice demonstrated a response signature to the cytokine IFNγ, which was elevated in the aged dura due to meningeal T cell accumulation. Chronic elevation of IFNγ in the meninges of young mice via AAV-mediated overexpression altered lymphatic adherans junctions and impaired CSF drainage to deep cervical lymph nodes—comparable to the deficits observed in aged mice. Direct disruption of lymphatic junctions via CSF-delivered VE-Cadherin disrupting antibodies was sufficient to phenocopy impairments in CSF drainage. Therapeutically, IFNγ neutralization in aged mice alleviated age-related impairments in meningeal lymphatic function. These data suggest manipulation of meningeal immunity as a viable therapeutic target to normalize CSF drainage in aged mice and alleviate the pathology in AD mice associated with impaired waste removal.