Expression and localization of human endothelin-converting enzyme-1 isoforms in symptomatic atherosclerotic disease and saphenous vein.

Abstract

Endothelin-converting enzyme (ECE-1) is a critical enzyme in the production of the potent vasoconstrictor peptide endothelin (ET-1). It has previously been shown that the levels of both ET-1 and ECE-1 are raised in atherosclerosis, but the possible relevance of the isoforms of ECE-1 in these changes has not yet been investigated. The aim of this study was to examine the expression of the ECE-1a and ECE-1c isoforms in human atherosclerotic pathologies. Immunohistochemical analysis was carried out on sections from atherosclerotic and non-atherosclerotic vascular tissue using a combination of ECE-1 isoform-specific antibodies, anti-alpha-actin antibodies to identify smooth muscle cells (SMC) and anti-CD68 antibodies to identify macrophages. ECE-1 isoform expression was also examined in cultured SMC and in macrophages isolated from human blood. Results indicated differences in isoform expression in atherosclerotic lesions, with distinct patterns of staining for ECE-1a and ECE-1c. ECE-1c immunoreactivity was seen in macrophages, and also correlated with actin staining. ECE-1a was also localized to macrophages and SMC. Results of this study suggest that these local changes influence the expression patterns of the ECE-1 isoforms within individual cell types. Correlation of these isoform expression patterns with the stage of atherosclerosis could provide novel indicators of disease progression.