CLINICAL ARTICLE Relationship between lectin-like oxidized low-density lipoprotein receptor 1 expression and preoperative echogenic findings of vulnerable carotid plaque Atsushi Saito & Miki Fujimura & Takashi Inoue & Hiroaki Shimizu & Teiji Tominaga Received: 15 July 2009 / Accepted: 1 December 2009 / Published online: 24 December 2009 # Springer-Verlag 2009 Abstract Purpose Lectin-like oxidized low-density lipoprotein 1 (LOX1) is an important cell surface receptor for the progression of atherosclerosis. Our purpose is to clarify the relationships of LOX1 and atherosclerotic factors for the vulnerability of carotid plaque and preoperative echo- genic findings. Methods We examined LOX1 expression, matrix metal- loproteinase (MMP)-2,9, and tissue inhibitor of MMP (TIMP)-2 by immunohistochemical analysis using carotid endarterectomy specimens obtained from 14 patients. Groups were divided into stable plaque group A and vulnerable plaque group B by preoperative echogenic findings of carotid plaques. Endothelial immunoreactivity was calculated, and the immunohistochemical findings were compared. Results LOX1 was remarkably expressed, especially in smooth muscle cells in vulnerable plaque and colocalized in MMP-9 positive cells and apoptotic cells. All LOX1, MMP-2,9, and TIMP2 were remarkably expressed in the subendothelial layer in group B compared with group A. The endothelial LOX1 index was 63.75±4.92 in group A and 83.0±5.02 in group B (p =0.02). The endothelial MMP-2 index was 24.38±5.50 in group A and 32.83± 6.79 in group B (p =0.01). The endothelial MMP-9 index was 46.13±6.31 in group A and 59.17±2.14 in group B (p =0.002). The endothelial TIMP-2 index had no signifi- cant difference between two groups (p =0.14). Conclusion LOX-1 may play an important role in the progression of vulnerable carotid plaque and might regulate vulnerable plaque formation in cooperation with MMPs and TIMP-2. Endothelial MMP-2 might suppress TIMP-2 activation in vulnerable plaques. Keywords Carotid plaque . LOX . Matrix metalloproteinase . Oxidized low-density lipoprotein Introduction The spontaneous rupture of vulnerable carotid plaques and subsequent thrombus formation are currently recognized as the primary mechanisms of atherothrombotic cerebral infarc- tions [9, 15]. Preoperative evaluation of the vulnerability of carotid plaques is therefore clinically important for stratify- ing risk and proving early treatment. Magnetic resonance imaging (MRI) and carotid echogram are important tools for noninvasive examination of carotid plaques, and high- intensity on T1- and T2-weighted MR images and low echogenic intensity are known to be lipid-rich unstable A. Saito : H. Shimizu : T. Tominaga Tohoku University Hospital Emergency Center, Konan Hospital, Sendai, Japan M. Fujimura : T. Inoue Department of Neurosurgery, Konan Hospital, Sendai, Japan A. Saito : M. Fujimura : T. Inoue : H. Shimizu : T. Tominaga Department of Neuroendovascular Therapy, Graduate School of Medicine, Tohoku University, Sendai, Japan A. Saito (*) Department of Neurosurgery, Graduate School of Medicine, Tohoku University, 1-1 Seiryomachi, Aoba, Sendai, Miyagi 980-8574, Japan e-mail: satsushi2002@yahoo.co.jp Acta Neurochir (2010) 152:589–595 DOI 10.1007/s00701-009-0573-1