Increase in tissue endothelin-1 and ETA receptor levels in human aortic valve stenosis.

AIMS Aortic valve stenosis (AS) is an actively regulated process like atherosclerosis, which is accompanied by changes e.g. in endothelin-related genes. However, the role of endothelin peptides in AS is unknown. METHODS AND RESULTS We characterized the expression of the endothelin system in aortic valves of patients with normal valves (n = 12), regurgitation, and fibrosis (n = 6) and AS (n = 18) by reverse-transcriptase-polymerase chain reaction and immunohistochemistry. The number of endothelin-1 (ET-1) positive cells was higher in AS than in control valves, while levels of ET-1 mRNA did not differ between groups. Endothelin receptor-A (ET(A)) mRNA levels were upregulated in stenotic valves (4.3-fold, P = 0.032) associated with a remarkable increase in number of ET(A)-immunopositive cells. ET(B)-receptor mRNA levels did not change during disease progression. Endothelin-converting enzyme-1 (ECE-1) mRNA levels were 42% lower (P = 0.007) in stenotic valves. Finally, because ET-1 and ECE-1 have binding site for activator protein-1 (AP-1), we measured AP-1 DNA binding by gel shift assays, which showed significantly lower (76%, P = 0.003) activity in AS. CONCLUSION AS is characterized by distinct upregulation of ET-1 and its target receptor ET(A), promoting growth, inflammation, and fibrosis. These findings suggest therapeutic potential for ET(A)-receptor antagonists in aortic valve calcification.