Abstract P615: Hypertension-Dependent Reprogramming of the Endothelial Transcriptome

Abstract

Hypertension has drastic consequences for the cardiovascular system and especially for endothelial cell health. Clinically this is observed through the repeated finding that hypertension is associated with endothelial dysfunction. Despite this strong evidence that hypertension leads to impairment of endothelial function, the molecular events that give rise to endothelial dysfunction are poorly characterized. To better understand how hypertension affects the health and function of endothelial cells at the molecular level, we utilized a mouse model of spontaneous hypertension (BPH/2J) with the overarching hypothesis that hypertension causes the transcriptional reprogramming of endothelial cells leading to endothelial dysfunction. First, we non-invasively quantified endothelial function from hypertensive and normotensive (BPN/3J) mice by measuring flow-mediated vasodilation with high-frequency ultrasound. We found that hypertensive mice failed to dilate their femoral artery while normotensive control mice dilated their femoral artery 17 ± 8% (Mean ± SEM). Next, we acutely isolated cardiac endothelial cells by magnetic-assisted cell sorting for endothelial marker CD31. Through this technique, we enriched our sample for endothelial cells (as defined by expression of two endothelial-specific cell-surface markers CD31 and CD102) to 92 ± 1% compared to 9 ± 1% in pre-magnetically sorted cells. Finally, we isolated RNA and transcriptionally profiled the endothelial cells from normotensive and hypertensive mice (n=3 mice per group) with an average depth of 30 million reads per sample with RNAseq. We found that over 4000 genes were differentially expressed between groups (FDR cutoff of .01). Using Ingenuity Pathways Analysis (Qiagen), we identified multiple pathways that were dysregulated in endothelial cells exposed to hypertension including those related to immune function, cell morphology and cell-to-cell communication. This work represents one of the first studies to utilize cell-specific RNAseq to quantify how endothelial cells are transcriptionally reprogrammed in a pathological state. It is our hope that this work will lead to targeted therapeutics to improve endothelial function in patients with hypertension.