Monitoring Endothelin-A Receptor Expression during the Progression of Atherosclerosis.

Miriam Stölting,Anne Helfen,Michael T Kuhlmann,Christiane Geyer,Eva Wardelmann,Carsten Höltke,Anke Hahnenkamp,Moritz Wildgruber,Marco V Usai

doi:10.3390/biomedicines8120538

Abstract

Cardiovascular disease remains the most frequent cause of death worldwide. Atherosclerosis, an underlying cause of cardiovascular disease, is an inflammatory disorder associated with endothelial dysfunction. The endothelin system plays a crucial role in the pathogenesis of endothelial dysfunction and is involved in the development of atherosclerosis. We aimed to reveal the expression levels of the endothelin-A receptor (ETAR) in the course of atherogenesis to reveal possible time frames for targeted imaging and interventions. We used the ApoE−/− mice model and human specimens and evaluated ETAR expression by quantitative rtPCR (qPCR), histology and fluorescence molecular imaging. We found a significant upregulation of ETAR after 22 weeks of high-fat diet in the aortae of ApoE−/− mice. With regard to translation to human disease, we applied the fluorescent probe to fresh explants of human carotid and femoral artery specimens. The findings were correlated with qPCR and histology. While ETAR is upregulated during the progression of early atherosclerosis in the ApoE−/− mouse model, we found that ETAR expression is substantially reduced in advanced human atherosclerotic plaques. Moreover, those expression changes were clearly depicted by fluorescence imaging using our in-house designed ETAR-Cy 5.5 probe confirming its specificity and potential use in future studies.

Highlights

Despite an improved prognosis for cardiovascular diseases, these remain the most frequent causes of death worldwide (WHO 2016)
We investigated the expression of the endothelin-A receptor (ETA R) in ApoE−/−
While the aorta of a C57Bl/6 mouse prior to a high-fat diet shows no atherosclerotic changes in the vessel wall (Figure 1A), long-term high-fat diet for 22 weeks reveals a high load of large fat-rich plaques around the bifurcation in the aortic arch of the ApoE−/− mouse aorta (Figure 1B) as typically observed during atherosclerosis development in humans

Summary

Introduction

Despite an improved prognosis for cardiovascular diseases, these remain the most frequent causes of death worldwide (WHO 2016). Atherosclerosis is perceived as an inflammatory disease whose pathogenesis starts with endothelial dysfunction, which is associated with increased vascular permeability and the storage of cholesterol in the subintimal space. Endothelin-1 (ET-1) and its associated G-protein coupled receptors ETA R and ETB R are involved in the pathogenesis of atherosclerosis [5,6,7,8]. This signaling axis plays an important role in various tumor entities [9] and in the pathophysiology of pulmonary arterial hypertension (PAH), where ET receptor antagonism has shown clinical efficacy [10]. Taken together there is strong evidence that ET receptors are crucial for atherogenesis and the understanding of their variable expression status in the course of plaque development is of tremendous importance for diagnostic and therapeutic approaches

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