Introduction

Endothelial cells are involved in many physiological and pathophysiological processes in the cardiovascular system, including angiogenesis, inflammation, fibrosis, or the regulation of vascular tone. As endothelial cells form the inner layer of the vasculature they are considered as important sensors for cardiovascular risk factors. To understand the impact of different risk factors on endothelial cell biology, we assessed the transcriptome of cardiac endothelial cells in experimental models of diabetes mellitus, arterial hypertension, or obesity.

Methods and results

Wildtype mice (n = 4 per group) were assigned to different models. To induce diabetes, mice were treated with streptozotocin (STZ, 60 mg/kg body weight for 5 days, 8 weeks follow-up). Arterial hypertension was induced by continuous infusion of aldosterone (1 mg/kg body weight/day) or angiotensin II (2 mg/kg body weight/day) for 2 weeks. As a model for obesity, mice received high fat diet (4.7 kcal/g, 45% fat) for 21 weeks. Cardiac endothelial cells were isolated using fluorescence assisted cell sorting (FACS) by labelling a single cell suspension from snap frozen heart tissue with FITC-conjugated lectin. Cell type-specific gene expression was assessed by RNA sequencing with subsequent bioinformatics analysis.

We found 446 genes differentially regulated by STZ, 938 genes by aldosterone, 227 genes by angiotensin II, and 57 genes by high fat diet, respectively. Interestingly, we observed a large overlap in gene expression after angiotensin II and aldosterone treatment (85 %), suggesting that the effect of angiotensin II is indirectly mediated by an upregulation of aldosterone. In line with this, we found high expression of the mineralocorticoid receptor (22 FPKM) while angiotensin II receptor 1 expression was not detectable in cardiac endothelial cells.

We observed an overlapping imprint of all four models on genes related to angiogenesis including VEGF receptor 2 (Kdr). Surprisingly, there was no clear effect on genes related to inflammation. In addition, we observed changes that were distinct between different models, e.g. an upregulation of genes related to fatty acid metabolism after STZ treatment.

Conclusion