Endothelial factors in the pathogenesis of aortic valve stenosis

Abstract

Calcified aortic valve disease represents a spectrum of disease spanning from mild aortic valve sclerosis to severe aortic valve stenosis (AS), being an actively regulated disease process and showing some hallmarks of atherosclerosis. The calcified aortic valve lesion develops endothelial injury and is characterized by inflammation, lipid accumulation, renin-angiotensin system activation and fibrosis. There is no approved pharmacological treatment available in AS.

This study was aimed to characterize gene expression of endothelial factors in aortic valves in patients representing different stages of calcified aortic valve disease to reveal new targets for pharmacological interventions in AS. Aortic valves obtained from 75 patients undergoing valve replacement surgery were studied. Expression of natriuretic peptides (ANP, BNP and CNP), their processing enzymes (corin and furin), natriuretic receptors (NPR-A, NPR-B and NPR-C), endothelin-1 (ET-1), endothelin converting enzyme-1 (ECE-1), endothelin receptors A and B (ET_A and ET_B), and apelin pathway (apelin and its receptor APJ) was characterized by reverse-transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry.

AS was characterized by distinct downregulation of gene expression of CNP, its processing enzyme furin and the target receptor NPR-B. Furthermore, increased amount of ET-1 and its target receptor ET_A as well as imbalance between ET_A and ET_B receptors and downregulated endothelial nitric oxide synthase (eNOS) gene expression were observed. Finally, gene expression of apelin and APJ receptor were significantly upregulated in stenotic valves when compared to controls in combination with disequilibrium between expression of angiotensin II receptors AT₁ and AT₂. The study provides a better understanding of molecular echanisms associated with calcific aortic valve disease and suggest potential targets for novel therapeutic interventions.