PLASMA-CHOLESTEROL TRANSFER AND ATHEROSCL EROSIS

Transfer processes in plasma are determinant in cholesterol metabolism . In many species, including man, there is an alternative route for th e disposal of cholesteryl esters (CE) in HDL via transfer to VLDL in e xchange for triglycerides (TG), a process dependent on a hydrophobic 7 4 kDa glycoprotein called cholesteryl ester transfer protein (CETP). I n vivo, cholesteryl esters transferred from HDL will contribute to LDL , to which VLDL is converted. Although the prevention of CE accumulati on in HDL may enhance the ability of HDL to take up more cholesterol f rom tissues, high rates of transfer may also increase the risk for ath eroma by increasing formation of atherogenic lipoproteins. Conversely, CE retained within HDL, if returned directly to the liver, would be e xpected to be beneficial. Moreover, in most conditions predisposing to atheroma, CETP activity is raised; whereas species with low or absent CETP activity are at low risk for atherosclerosis.