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The lectin-like oxidised low density lipoprotein receptor-1, LOX-1, is expressed in endothelial cells and macrophages among others. Its expression can be induced by a variety of stimuli such as oxidised LDL, endothelin-1, angiotensin II and shear stress. LOX-1 seems to be important for the induction of endothelial dysfunction and is implicated in atherosclerotic plaque vulnerability.
Atherectomy specimens were obtained from 37 patients (mean age 62.5±9.7 years, body mass index 28.6±5.3 kg/m2; n=30 with chest pain/angina pectoris), who underwent medially indicated directional coronary atherectomy in the Department of Internal Medicine B, University Medicine Greifswald, between July 2001 and April 2005, and were immediately frozen in liquid nitrogen. Human coronary atherectomy specimens were cut into 5 μm-slices using a kryotom and stained with haematoxylin and eosin (H&E), Oil Red O (lipids) and Elastica-van Gieson (collagen). LOX-1 was detected by immunofluorescence using a FITC-labelled rabbit polyclonal antibody against amino acids 143 to 271 of human LOX-1. Digital images were analysed with Corel PHOTO-PAINT 12, SCION Image, and SigmaPlot 11. Correlations between signal intensities for LOX-1 expression and patients’ parameters were analysed by Spearman Rank Order testing. Patients gave informed consent. The study protocol complied with the Declaration of Helsinki and was approved by the local ethics committee.
LOX-1 expression correlated significantly with lipid content of the coronary atherectomy specimens. LOX-1 expression tended to be higher in specimens from patients with acute coronary syndrome (n=11) and to be lower in patients receiving statins (n=16). However, no correlations were found between LOX-1 expression and grade of stenosis, plaque localisation, age, sex, body mass index, smoking (n=15), hypertension (n=31), diabetes mellitus type II (n=9), and dyslipoproteinaemia (n=32).
LOX-1 expression in plaques was positively correlated with lipid contents of plaque material and tended to be higher in patients with acute coronary syndrome and to be lower if patients had received statins. High LOX-1 expression in the atherosclerotic plaque may contribute to plaque instability.