A molecular map of lymph node blood vascular endothelium at single cell resolution
Ontology highlight
ABSTRACT: Blood vascular endothelial cells (BECs) control the immune response by regulating immune cell recruitment, metabolite exchange and blood flow in lymphoid tissues. However, the diversity of BEC and their origins during immune angiogenesis remain poorly understood. Here we profile transcriptomes of BEC from mouse peripheral lymph nodes and map key phenotypes to the vasculature. Our analysis identifies multiple novel subsets including a venous population whose gene signature predicts an unexpectedly selective role in myeloid cell (vs lymphocyte) recruitment to the medulla, confirmed by 2 photon videomicroscopy. We define five phenotypes of capillary lining BEC including a capillary resident regenerative population (CRP) that displays stem cell and migratory gene signatures and contributes to homeostatic BEC turnover and to vascular neogenesis after immunization. Trajectory analyses reveal retention of developmental programs along a progression of cellular phenotypes from CRP to mature venous and arterial BEC subsets. Overall, our single cell atlas provides a molecular blueprint of the lymph node blood vasculature and defines subset specialization for immune cell recruitment and vascular homeostasis.
Project description:This file contains gene microarray data from FACS purified mouse high endothelial cells and capillary endothelial cells from peripheral lymph nodes, mesenteric lymph nodes, and Peyer’s patches. The data will allow for better understanding of the specialization of high endothelial venules (HEV) and their role in lymphocyte recruitment from the blood; the tissue-specific differentiation of lymphoid tissue vasculature; and the specialized features of capillary vs. post-capillary endothelium, including differences in signaling pathways, adhesive properties and mechanisms of hemostasis. We analyzed transcript expression data from vascular endothelial subsets from BALB/c mouse lymphoid tissue.
Project description:Repair of the pulmonary vascular bed and the origin of new vasculature remains underexplored despite the critical necessity to meet oxygen demands after injury. Given their critical role in angiogenesis in other settings, we investigated the role of venous endothelial cells in endothelial regeneration after adult lung injury. Using single cell transcriptomics, we identified the norepinephrine transporter Slc6a2 as a marker of pulmonary venous endothelial cells and targeted that locus to generate a venous-specific, inducible Cre mouse line. Contributions of the venous endothelial cells to angiogenesis were examined during postnatal development, adult viral injury, and adult hyperoxia injury. Remarkably, we observed that venous endothelial cells proliferate into the adjacent capillary bed upon influenza injury and hyperoxia injury, but not during normal postnatal development. Imaging analysis demonstrated that venous endothelial cells exhibit the ability to proliferate and differentiate into general capillary and CAR4 expressing aerocyte capillary endothelial cells after infection, thus contributing to repair of the capillary plexus vital for gas exchange. Single cell transcriptomic analysis of Slc6a2 lineage traced cells confirmed these observations, with progeny exhibiting significant loss of venous identity and gain of capillary marker expression upon injury resolution. Our studies thus establish that venous endothelial cells exhibit demonstrable progenitor capacity upon respiratory viral injury and sterile injury, contributing to repair of the alveolar capillary bed responsible for pulmonary function.
Project description:Oncogenic mutations in PIK3CA, encoding p110α-PI3K, are a common cause of venous and lymphatic malformations. Vessel type-specific disease pathogenesis is poorly understood, hampering development of efficient therapies. Here, we reveal a new immune-interacting subtype of Ptx3-positive dermal lymphatic capillary endothelial cells (iLECs) that recruit pro-lymphangiogenic macrophages to promote progressive lymphatic overgrowth. Mouse model of Pik3caH1047R-driven vascular malformations showed that proliferation was induced in both venous and lymphatic ECs, but sustained selectively in LECs of advanced lesions. Single-cell transcriptomics identified the iLEC population, residing at lymphatic capillary terminals of normal vasculature, that was expanded in Pik3caH1047R mice. Expression of pro-inflammatory genes, including monocyte/macrophage chemokine Ccl2, in Pik3caH1047R-iLECs was associated with recruitment of VEGF-C-producing macrophages. Macrophage depletion, CCL2 blockade or anti-inflammatory COX-2 inhibition limited Pik3caH1047R-driven lymphangiogenesis. Thus, targeting the paracrine crosstalk between iLECs and macrophages provides a new therapeutic opportunity for lymphatic malformations. Identification of iLECs further indicates that peripheral lymphatic vessels not only respond to but also actively orchestrate inflammatory processes.
Project description:Aims: Coronary vasculature formation is a critical event during cardiac development, essential for heart function throughout perinatal and adult life. However, current understanding of coronary vascular development has largely been derived from transgenic mouse models. The aim of this study was to characterise the transcriptome of the human fetal cardiac endothelium using single-cell RNA sequencing (scRNA-seq) to provide critical new insights into the cellular heterogeneity and transcriptional dynamics that underpin endothelial specification within the vasculature of the developing heart. Methods and Results: We acquired scRNA-seq data of over 10,000 fetal cardiac endothelial cells (EC), revealing divergent EC subtypes including endocardial, capillary, venous, arterial, and lymphatic populations. Gene regulatory network analyses predicted roles for SMAD1 and MECOM in determining the identity of capillary and arterial populations, respectively. Trajectory inference analysis suggested an endocardial contribution to the coronary vasculature and subsequent arterialisation of capillary endothelium accompanied by increasing MECOM expression. Comparative analysis of equivalent data from murine cardiac development demonstrated that transcriptional signatures defining endothelial subpopulations are largely conserved between human and mouse. Furthermore, we revealed that knockdown of MECOM in human embryonic stem cell-derived EC (hESC-EC) resulted in an increase in venous EC marker expression, validating our prediction of its role in arterial EC identity. Conclusions: scRNA-seq of the human fetal cardiac endothelium identified distinct EC populations. A predicted endocardial contribution to the developing coronary vasculature was identified, as well as subsequent arterial specification of capillary EC. Loss of MECOM in hESC-EC increased venous EC marker expression, suggesting a role in maintaining arterial EC identity.
Project description:The heterogeneity of endothelial cells (ECs), lining blood vessels, across tissues remains incompletely inventoried. We constructed an atlas of >32,000 single-EC transcriptomic data from 11 tissues of the model organism Mus musculus. We propose a new classification of EC phenotypes based on transcriptome signatures and inferred putative biological features. We identified top-ranking markers for ECs from each tissue. ECs from different vascular beds (arteries, capillaries, veins, lymphatics) resembled each other across tissues, but only arterial, venous and lymphatic (not capillary) ECs shared markers, illustrating a greater heterogeneity of capillary ECs. We identified high-endothelial-venule and lacteal-like ECs in the intestines, and angiogenic ECs in healthy tissues. Metabolic transcriptomes of ECs differed amongst spleen, lung, liver, brain and testis, while being similar for kidney, heart, muscle and intestines. Within tissues, metabolic gene expression was heterogeneous amongst ECs from different vascular beds, altogether highlighting large EC heterogeneity.
Project description:Extracellular Vesicles (EVs) are crucial mediators of cell-to-cell communication in physiology but also in pathological conditions. Specifically, EVs released from the vasculature into blood were found to be quantitatively and qualitatively different in diseases versus healthy states. However, our understanding on EVs derived from the lymphatic system is still scarce. In this study we compared the mRNA and miRNA expression in blood vascular (BEC) and lymphatic (LEC) endothelial cells. After characterization of the EVs by fluo-triggered flow cytometry, nanoparticle tracking analysis and cryo-EM we utilized small RNA-sequencing to characterize miRNA signatures in the EVs and thereof identify cell-type specific miRNAs in BEC and LEC. We believe that our data provide a solid basis for further functional in vitro and in vivo studies addressing the role of EVs in the blood and lymphatic vasculature.
Project description:Extracellular Vesicles (EVs) are crucial mediators of cell-to-cell communication in physiology but also in pathological conditions. Specifically, EVs released from the vasculature into blood were found to be quantitatively and qualitatively different in diseases versus healthy states. However, our understanding on EVs derived from the lymphatic system is still scarce. In this study we compared the mRNA and miRNA expression in blood vascular (BEC) and lymphatic (LEC) endothelial cells. After characterization of the EVs by fluo-triggered flow cytometry, nanoparticle tracking analysis and cryo-EM we utilized small RNA-sequencing to characterize miRNA signatures in the EVs and thereof identify cell-type specific miRNAs in BEC and LEC. We believe that our data provide a solid basis for further functional in vitro and in vivo studies addressing the role of EVs in the blood and lymphatic vasculature.
Project description:This file contains gene microarray data from FACS purified mouse high endothelial cells and capillary endothelial cells from peripheral lymph nodes, mesenteric lymph nodes, and Peyer’s patches. The data will allow for better understanding of the specialization of high endothelial venules (HEV) and their role in lymphocyte recruitment from the blood; the tissue-specific differentiation of lymphoid tissue vasculature; and the specialized features of capillary vs. post-capillary endothelium, including differences in signaling pathways, adhesive properties and mechanisms of hemostasis.
Project description:Mature endothelial cells (ECs) are heterogeneous, with subtypes defined by tissue origin and by position within the vascular bed. Here, we performed scRNA-seq with mouse embryonic ECs and identified 19 subclusters, including Etv2+Bnip3+ early EC progenitors. Most of these subtypes were grouped by their vascular-bed types, while ECs from brain, heart and liver were grouped by their tissue origins. Compared to arterial ECs (aECs), embryonic venous (vECs) and capillary ECs (cECs) shared less markers with their adult counterparts. cECs showed some venous characteristics. One cEC cluster with both venous and capillary features served as a branch point for aEC and vEC lineages. aECs and vECs showed distinct transcriptional regulatory networks.
Project description:Following acute injury, the capillary vascular bed in the lung must be repaired to reestablish gas exchange between pulmonary endothelial cells (ECs) lining these vessels and the alveolar epithelium. However, the factors that control EC stress response and drive regeneration of pulmonary capillaries remain incompletely understood. Viral infections such as influenza and COVID-19 may indirectly damage lung vasculature through loss of epithelial gas exchange partners or through signaling from infiltrating immune cells. To prevent excessive tissue damage and to renew the endothelium, ECs must both withstand cellular stress and proliferate after injury. Here, we show that the transcription factor and immediate early gene Atf3 is essential for both responses in the mouse lung after influenza infection. Atf3 expression defines a subpopulation of capillary ECs enriched in genes involved in cellular response to stress, angiogenesis, and vascular development. Endothelial loss of ATF3 results in defective alveolar regeneration: in the absence of ATF3, ECs exhibit increased apoptosis and decreased proliferation, resulting in an emphysema-like phenotype with enlarged alveolar airspaces lined with regions of lost vasculature. These data implicate ATF3 as an essential component of the vascular response to acute lung injury that is required for successful lung regeneration.