Acta Histochemica 116 (2014) 1148–1158 Contents lists available at ScienceDirect Acta Histochemica jo ur nal homepage: www.elsevier.de/acthis ADAM-10 could mediate cleavage of N-cadherin promoting apoptosis in human atherosclerotic lesions leading to vulnerable plaque: A morphological and immunohistochemical study Giuseppe Musumeci a,∗ , Raymond Coleman b , Rosa Imbesi a , Gaetano Magro c , Rosalba Parenti d , Marta Anna Szychlinska a , Rosario Scuderi e , Claudio Salvatore Cinà f , Sergio Castorina a,f , Paola Castrogiovanni a a Department of Bio-Medical Sciences, Human Anatomy and Histology Section, School of Medicine, University of Catania, Catania, Italy b Department of Anatomy & Cell Biology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel c Department G.F. Ingrassia, Azienda Ospedaliero-Universitaria “Policlinico-Vittorio Emanuele” Anatomic Pathology, University of Catania, Catania, Italy d Department of Bio-Medical Sciences, Section of Physiology, University of Catania, Catania, Italy e Department of Medical and Pediatric Sciences, University of Catania, Catania, Italy f Fondazione Mediterranea “G.B. Morgagni, 95125, Catania, Italy a r t i c l e i n f o Article history: Received 21 May 2014 Received in revised form 1 June 2014 Accepted 2 June 2014 Keywords: Caspase-3 N-cadherin ADAM-10 Atherosclerotic plaque Vascular smooth muscle cells. a b s t r a c t Atherosclerosis remains a major cause of mortality. Whereas the histopathological progression of atherosclerotic lesions is well documented, much less is known about the development of unstable or vulnerable plaque, which can rupture leading to thrombus, luminal occlusion and infarct. Apoptosis in the fibrous cap, which is rich in vascular smooth muscle cells (VSMCs) and macrophages, and its subsequent weakening or erosion seems to be an important regulator of plaque stability. The aim of our study was to improve our knowledge on the biological mechanisms that cause plaque instability in order to develop new therapies to maintain atherosclerotic plaque stability and avoid its rupture. In our study, we collected surgical specimens from atherosclerotic plaques in the right or left internal carotid artery of 62 patients with evident clinical symptoms. Histopathology and histochemistry were performed on wax-embedded sections. Immunohistochemical localization of caspase-3, N-cadherin and ADAM-10 was undertaken in order to highlight links between apoptosis, as expressed by caspase-3 immunostaining, and possible roles of N-cadherin, a cell-cell junction protein in VSMCs and macrophages that provides a pro-survival signal reducing apoptosis, and ADAM-10, a “disintegrin and metalloproteases” that is able to cleave N-cadherin in glioblastomas. Our results showed that when apoptosis, expressed by caspase-3 immunostaining, increased in the fibrous cap, rich in VSMCs and macrophages, the expression of N-cadherin decreased. The decreased N-cadherin expression, in turn, was linked to increased ADAM-10 expression. This study shows that apoptotic events are probably involved in the vulnerability of atherosclerotic plaque. © 2014 Elsevier GmbH. All rights reserved. Introduction Atherosclerosis remains a major cause of mortality in the West- ern world. Atherosclerotic lesions are characterized by a thickening of the arterial wall and development of plaque. The histopatho- logical progression of atherosclerotic plaque has been well documented in experimental animals, in particular in genetically ∗ Corresponding author. Department of Bio-Medical Sciences, Human Anatomy and Histology Section, School of Medicine, University of Catania, 95123 Catania (CT), Italy. E-mail address: g.musumeci@unict.it (G. Musumeci). modified mice (Coleman et al., 2006; Bonomini et al., 2008) and also in humans, though the etiology and pathophysiological mech- anisms remain a subject for continuing debate. Atherosclerosis is a progressive disease characterized by accumulation of choles- terol deposits in macrophages (“foam cells”) in large and medium arteries, which subsequently develop into complex lesions with accumulation of hypocellular lipid-rich necrotic cores, cholesterol crystals and VSMCs. The developing lesions protruding into the lumen are covered with a collagenous fibrous cap. The major recog- nized clinical problems associated with atherosclerosis have been associated with unstable fibrous caps (vulnerable plaque), which are often eroded with subsequent rupture leading to thrombi, occlusion of the lumen and infarct (Ross, 1999; Lusis, 2000; http://dx.doi.org/10.1016/j.acthis.2014.06.002 0065-1281/© 2014 Elsevier GmbH. All rights reserved.