Single-cell RNA-seq profiling of mouse endothelial cells in response to pulmonary arterial hypertension

Aims
Endothelial cell dysfunction plays a critical role in the initiation and pathogenesis of pulmonary arterial hypertension (PAH). We aimed to characterise the endothelial cell dynamics in PAH at a single cell resolution.
Methods and Results
We carried out single-cell RNA sequencing of lung endothelial cells isolated from an endothelial cell lineage tracing mouse model in control and SU5416/Hypoxia-induced PAH conditions. Endothelial cell populations corresponding to the different lung vessel types, including two distinct capillary populations, could be identified in both control and PAH mice. Differential gene expression analysis revealed novel global and vesseltype specific responses in endothelial cells due to PAH. Global changes included the upregulation of the major histocompatibility complex class II pathway, supporting a role for endothelial cells in the inflammatory response in PAH. We also identified a PAH response specific to the second capillary endothelial cell populations, with the upregulation of genes involved in cell motility and angiogenesis. Comparison with human genetics and transcriptomics data revealed the differential regulation in PAH samples of four genes with variants associated to PAH and five genes up-regulated in PAH endothelial cells in both human and mouse scRNA-seq. Among them, Aqp1 and
Adam15 genes represent promising new candidates to target endothelial dysfunction. Finally, we identified zonation-dependent changes across the arteriovenous axis in PAH using an in-silico cell ordering approach and showed the upregulation of the Serine/threonine-protein kinase Sgk1 at the junction between the macro- and microvasculature.
Conclusions
This study uncovers endothelial cell transcriptomics changes in PAH at a high
resolution, revealing novel candidates relevant to PAH.