Erythrocyte-associated apolipoprotein B and its relationship with clinical and subclinical atherosclerosis

Background Apolipoprotein (apo) B-containing lipoproteins are closely linked to atherogenesis. These lipoproteins are transported in plasma and are also associated with blood leucocytes. Our aim was to investigate whether apoB-containing lipoproteins are also present on the surface of erythrocytes and investigate the relationship with the presence of atherosclerosis in a cross-sectional study. Materials and methods Erythrocyte-bound apoB (ery-apoB) was measured by flowcytometry in subjects with (CAD+) and without coronary artery disease (CAD-), based on coronary angiography or on a history of cardiovascular disease. Intima media thickness (IMT) measurements were carried out using B-mode ultrasound. The relationship between ery-apoB and clinical and subclinical atherosclerosis was evaluated with binary logistic regression. Results A total of 166 subjects were included (40 CAD+ and 126 CAD-). ApoB was detected on freshly isolated erythrocytes (range: 0·1-5·5 au; mean±SEM 0·86±0·09 au) in all but nine subjects (four CAD+ and five CAD-). Ery-apoB was lower in CAD+ (0·62±0·09 au) compared to CAD- (1·18±0·10 au; P<0·001). Higher ery-apoB was associated with a lower risk of CAD (adjusted OR: 0·003 (95% CI: 0·001-0·08; P<0·001), but the protective effect was diminished with increasing age (adjusted OR: 1·10 (95% CI: 1·04-1·16; P<0·001). IMT was increased in CAD+ subjects (0·77±0·13mm) compared to CAD- (0·57±0·14mm; P<0·001). A significant negative association was found between ery-apoB and IMT (β=-0·214: 95% CI -0·284 to -0·145; P<0·001). There was no association between ery-apoB and plasma apoB (Pearson's r=-0·45; P=0·57). Conclusions Human erythrocytes carry apoB-containing lipoproteins. Subjects with atherosclerosis have lower ery-apoB. High ery-apoB may be protective against atherosclerosis and may reflect an alternative blood cell-mediated lipoprotein transport system in the circulation, in which these lipoproteins less likely interact with the endothelium. © 2011 The Authors. European Journal of Clinical Investigation

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