Single-cell analysis reveals heterogeneity of high endothelial venules and different regulation of genes controlling lymphocyte entry to lymph nodes

High endothelial venules (HEVs) are specialized blood vessels allowing recirculation of naïve lymphocytes through lymphoid organs. Here, using full length single-cell RNA sequencing, RNA-FISH, flow cytometry and immunohistofluorescence, we reveal the heterogeneity of HEVs in adult mouse peripheral lymph nodes (PLNs) under conditions of homeostasis, antigenic stimulation and after inhibition of lymphotoxin-b receptor (LTbR) signaling. We demonstrate that HEV endothelial cells are in an activated state during homeostasis, and we identify the genes characteristic of the differentiated HEV phenotype. We show that LTbR signaling regulates many HEV genes and pathways in resting PLNs, and that immune stimulation induces a global and temporary inflammatory phenotype in HEVs without compromising their ability to recruit naïve lymphocytes. Most importantly, we uncover differences in the regulation of genes controlling lymphocyte trafficking, Glycam1, Fut7, Gcnt1, Chst4, B3gnt3 and Ccl21a, that have implications for HEV function and regulation in health and disease. Overall design: Comparison of High Endothelial Cells and Blood Endothelial Cells from mouse lymph nodes under 4 different conditions with a total of 220 single cells.

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Veerman K, Tardiveau C, Martins F, Coudert J, Girard JP