Angiotensin-converting enzyme expression in human carotid artery atherosclerosis

Area of Science:

• Cardiovascular Biology
• Vascular Pathology
• Molecular Medicine

Background:

• Angiotensin-converting enzyme (ACE) inhibitors show promise in animal models of atherosclerosis and human myocardial infarction.
• While ACE components are found in coronary arteries, their presence in carotid arteries, a common atherosclerosis site, is unknown.
• Carotid artery atherosclerosis is a significant cause of stroke.

Purpose of the Study:

• To investigate the presence and localization of ACE mRNA and protein in human carotid atheromatous lesions.
• To determine if ACE expression is associated with specific cell types within atherosclerotic plaques.
• To understand the role of ACE in carotid artery plaque progression.

Main Methods:

• Analysis of 24 human carotid endarterectomy specimens with advanced atherosclerotic lesions (Stary type V and VI).
• Localization of ACE mRNA and protein using in situ hybridization and immunohistochemistry.
• Colocalization of ACE with cell-specific markers (smooth muscle cells, endothelial cells, macrophages, lymphocytes).

Main Results:

• ACE protein and mRNA were detected in the intima of carotid plaques, primarily within macrophages and microvessels.
• ACE expression was significantly higher in macrophage-rich areas and plaque shoulder regions.
• Microvessel ACE expression was associated with inflammation; smooth muscle cells showed minimal ACE staining.

Conclusions:

• Atherosclerosis alters ACE production in the carotid artery, with increased transcription and translation in inflamed plaque regions.
• Inflammation-driven ACE expression in carotid plaques may contribute to the progression of atherosclerosis.
• These findings highlight a potential mechanism linking inflammation and ACE in vascular disease.