A molecular map of murine lymph node blood vascular endothelium at single cell resolution

Kevin Brulois,Anusha Rajaraman,Bin Zhou,Jasper J Koning,Kristy Red-Horse,Denis Dermadi,Dietmar Vestweber,Ania Bogoslowski,Eugene C Butcher,Edward O’Hara,Ralf H Adams,Junliang Pan,Hiroto Kawashima,Paul Kubes,Helena Kiefel,Sofia Nordling,Agata Szade,Milladur Rahman,Reina E Mebius

doi:10.1038/s41467-020-17291-5

Abstract

Blood vascular endothelial cells (BECs) control the immune response by regulating blood flow and immune cell recruitment in lymphoid tissues. However, the diversity of BEC and their origins during immune angiogenesis remain unclear. Here we profile transcriptomes of BEC from peripheral lymph nodes and map phenotypes to the vasculature. We identify multiple subsets, including a medullary venous population whose gene signature predicts a selective role in myeloid cell (vs lymphocyte) recruitment to the medulla, confirmed by videomicroscopy. We define five capillary subsets, including a capillary resident precursor (CRP) that displays stem cell and migratory gene signatures, and contributes to homeostatic BEC turnover and to neogenesis of high endothelium after immunization. Cell alignments show retention of developmental programs along trajectories from CRP to mature venous and arterial populations. Our single cell atlas provides a molecular roadmap of the lymph node blood vasculature and defines subset specialization for leukocyte recruitment and vascular homeostasis.

Highlights

Blood vascular endothelial cells (BECs) control the immune response by regulating blood flow and immune cell recruitment in lymphoid tissues
Clusters extending to the termini of the arterial, capillary resident regenerative population (CRP), and high endothelial venules’ (HEV) branches were further separated to distinguish cells that were most distinct from the bulk of EC: these cells are enriched for genes associated with mature arterial (e.g., Gkn[3], Bmx) or HEV (Chst[4], Glycam1) differentiation, or in the case of CRP, for genes associated with endothelial specification during early development or with stem cells (e.g., Ets[2], Cxcr[4], Nes) (Fig. 1f)
In conjunction with their expression of genes involved in embryonic vascular development and their enrichment in cells undergoing basal cell division, the results suggest that CRP are a poised regenerative subset or progenitor that contributes to vessel maintenance at steady state and to neogenesis of EC including high endothelial cells (HEC) during lymph nodes (LN) angiogenesis

Summary

Introduction

Blood vascular endothelial cells (BECs) control the immune response by regulating blood flow and immune cell recruitment in lymphoid tissues. We identify multiple subsets, including a medullary venous population whose gene signature predicts a selective role in myeloid cell (vs lymphocyte) recruitment to the medulla, confirmed by videomicroscopy. We define five capillary subsets, including a capillary resident precursor (CRP) that displays stem cell and migratory gene signatures, and contributes to homeostatic BEC turnover and to neogenesis of high endothelium after immunization. Our single cell atlas provides a molecular roadmap of the lymph node blood vasculature and defines subset specialization for leukocyte recruitment and vascular homeostasis. We confirm known features of high endothelium[6,7], identify endothelial subsets, describe unexpected diversity among capillary cells and demonstrate a distinctive role of medullary veins in selective myeloid cell recruitment. Genetic lineage tracing suggests that CRP function as progenitors, contributing to neogenesis of the blood vascular endothelium including high endothelium in immune angiogenesis

Methods

Results

Conclusion