Differential localisation of the renin-angiotensin system in de-novo lesions and in-stent restenotic lesions in in-vivo human coronary arteries

Objective: Different components of the renin-angiotensin system (RAS) have been demonstrated in atherosclerotic plaques. However, the involvement of the RAS in in-stent restenosis is not clear. We studied the differential immunolocalisation of angiotensin converting enzyme (ACE) and the angiotensin II type 1 (AT1) receptor in de-novo stenotic lesions and in-stent restenotic lesions in human coronary arteries. Methods: Using a pullback atherectomy catheter, biopsies from de-novo coronary lesions (n = 19) and in-stent restenotic lesions (n = 19) were obtained. The biopsies were immunostained for vascular smooth muscle cells (VSMCs), macrophages, ACE and the AT I receptor. Results: In biopsies from de-novo stenotic lesions ACE-positive macrophages were more numerous than in in-stent restenotic lesions (P=0.002). Moreover, in the latter lesions, ACE-positive macrophages decreased when the time interval of stent implantation was longer. On the other hand, in-stent restenotic lesions contained predominantly young VSMCs, which abundantly expressed AT1 receptors. Conclusions: Lesional ACE expression is not a prominent feature of in-stent restenotic lesions. In contrast, AT1 receptors are abundantly expressed on young VSMCs. In de-novo lesions ACE and AT1 receptors were found on macrophages and VSMCs. which were present in all specimens. (C) 2003 European Society of Cardiology. Published by Elsevier B.V. All rights reserved