Plasma 27-hydroxycholesterol/cholesterol ratio is increased in low high density lipoprotein-cholesterol healthy subjects

Abstract

Sterol 27-hydroxylase converts cholesterol to 27-hydroxycholesterol (27-OHC) which is widely distributed among tissues and is expressed at high levels in the vascular endothelium and macrophages. There is a continuous flow of this oxysterol from the tissues into the liver; where it is converted to bile acids. Objective: Measure plasma concentrations of 27-OHC in subjects that differ according to their plasma HDL-C concentration. Methods: Healthy men presenting low HDL-C (<1,03 mmol/L), n = 18 or high HDL-C (>1.55 mmol/L), n 18, BMI <30 kg/m(2) were recruited after excluding secondary causes that might interfere with their plasma lipid concentrations such as smoking, heavy drinking and diabetes. Blood samples were drawn after a 12 h fasting period for the measurement of 27-OHC by the combined GC/MS analysis utilizing deuterium-label internal standards. Results: The plasma ratio 27-OHC/total cholesterol (median and range nmoL/mmoL) was 50.41 (27.47-116.00) in the High HDL-C subjects and 6334 (36.46-91.18) in the Low HDL-C subjects (p = 0.0258). Conclusion: Our data indicate that the production of 27-0HC by extrahepatic tissues and its transport to the liver may represent an alternative pathway for a deficient reverse cholesterol transport system when plasma HDL-C is low.