Prevalence and Pathology of Amyloid in Atherosclerotic Arteries

Abstract

To the Editor: Apolipoprotein AI (AApoAI)–associated amyloidosis is characterized by the deposition of apolipoprotein AI (apoAI) and occurs as a hereditary and a nonhereditary form. Hereditary AApoAI amyloidosis is a systemic disease leading to the deposition of amyloid in various organs and tissues and is caused by germline mutations in the APOA1 gene. Nonhereditary AApoAI amyloid is far more prevalent and characterized by deposits of nonvariant protein in atherosclerotic arteries.1–3 Despite being linked to the most common cause of morbidity and mortality in Western societies, nonhereditary AApoAI amyloid has achieved only little attention.1–4 It shares several striking similarities with secondary or reactive AA amyloidosis. Nonhereditary AApoAI amyloid occurs in the background of a local chronic inflammatory reaction, it originates from an apolipoprotein that largely associates with high-density lipoproteins (HDLs), and apoAI-containing HDL is endocytosed and retroendocytosed by macrophages, which, in themselves, are able to form amyloid in vitro. Finally, AApoAI amyloidosis is characterized by the deposition of proteolytic fragments of the precursor protein, leading us to speculate that proteolysis is involved in the pathogenesis of AApoAI amyloid.1,3 The aim of this study was to gain further insights into the pathology of nonhereditary AApoAI amyloid. See cover The prevalence and spatial distribution of amyloid, macrophages, cathepsin B (CathB), cathepsin K (CathK), cathepsin L (CathL), and carboxy methyl lysine (CML) was studied using carotid artery specimens obtained from a consecutive series of all 225 patients undergoing carotid endarterectomy with polyester patch angioplasty (Table I, available online at http://atvb.ahajournals.org) during the period from 1997 to 2003. All patients were scheduled for elective therapeutic endarterectomy and gave written informed consent in the surgical procedure. Patient characteristics were retrieved from hospital records. This study was in accordance with the guidelines of the ethics committee of the University of Magdeburg. Tissue samples were …