Submitted on July 17, 2006
Revised on February 27, 2007
Accepted on February 27, 2007
Inability of HDL from abdominally obese subjects to counteract the inhibitory effect of oxidized LDL on endothelium-dependent vasorelaxation
Laurence Persegol, Bruno Verges, Philippe Gambert, and Laurence Duvillard
Biochimie Medicale, INSERM U 866, Dijon 21079
Corresponding Author: laurence.duvillard{at}chu-dijon.fr
Abdominal obesity is associated with a decreased plasma concentration of HDL cholesterol and with qualitative modifications of HDL such as triglyceride enrichment. Our aim was to determine, on isolated aorta rings, whether HDL from obese subjects can counteract the inhibitory effect of oxidized (ox)-LDL on endothelium dependent vasodilation as efficiently as HDL from normolipidemic, lean subjects. Plasma triglycerides were 74% higher (p< 0.005) in obese subjects compared to controls and apolipoprotein AI and HDL cholesterol concentrations were respectively 12 and 17% lower (p<0.05). HDL from control subjects significantly reduced the inhibitory effect of ox-LDL on vasodilation (Emax = 82.1±8.6 vs 54.1±8.1%, p<0.0001), but HDL from obese subjects had no effect (Emax=47.2±12.5 vs 54.1±8.1%, NS). In HDL from abdominally obese subjects compared to HDL from controls, the apoAI content was 12% lower (p<0.05) and the triglyceride-to cholesteryl ester ratio was 36% higher (p=0.08)). Emax (ox-LDL + HDL) was correlated with HDL apoAI content and triglyceride-to-cholesteryl ester ratio (respectively r=0.36 and r=-0.38, p<0.05). We conclude that in abdominally obese subjects, the ability of HDL to counteract the inhibitory effect of ox-LDL on vascular relaxation is impaired. This could contribute to the increased cardiovascular risk observed in these subjects.
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