Effects of vitamin E and HMG-CoA reductase inhibition on cholesteryl ester transfer protein and lecithin-cholesterol acyltransferase in hypercholesterolemia

BACKGROUNDThe enzyme lecithin-cholesterol acyl transferase (LCAT) esterifies free cholesterol on highdensity lipoprotein (HDL) and the cholesteryl ester transfer protein (CETP) transfers cholesteryl esters to very-low-density lipoproteins (VLDL) and low-density lipoproteins (LDL). Using statins, contradictory findings have been made regarding CETP activity in normolipidemic individuals and in those with familial dysbetatlipoproteinemia. In contrast, LCAT activity appears to be unaffected by simvastatin. Antioxidants have also been proposed for use in anti-atherosclerotic treatment, because the oxidation of LDL may have a key role in the pathophysiology of atherogenesis. OBJECTIVETo investigate, in hypercholesterolemic patients, whether a combination of pravastatin with the antioxidant, vitamin E, has greater effects on the activity of CETP and of LCAT than does pravastatin alone. METHODSThis placebo-diet-controlled multicenter trial included 220 hypercholesterolemic patients who were assigned randomly to groups to receivediet and 20–40 mg pravastatin (n = 52), diet and pravastatin in combination with 100 mg/day vitamin E (100 IU) as DL-α-tocopherol (n = 56), diet and α-tocopherol (n = 60), or diet associated with placebo (n = 52). Plasma LCAT activity was determined using excess exogenous substrate, containing [H]cholesterol. Plasma CETP activity was measured in the supernatant fraction after precipitation of endogenous apo B-containing lipoproteins with phosphotungstate-Mg+. The exchange of cholesteryl esters between [C]cholesteryl esterlabeled LDL and unlabeled HDL was measured during a 16-h incubation, while LCAT was inhibited. RESULTSThe addition of pravastatin to the diet induced a significant decrease in plasma CETP activity (P< 0.05); this effect was less evident in the group cotreated with vitamin E. For the first time, it was shown that CETP concentrations increased significantly after vitamin E alone (P< 0.05). No significant differences in the plasma activity of LCAT were observed among the groups. CONCLUSIONSPravastatin reduced CETP activity, but not that of LCAT. Addition of vitamin E prevented the decrease in CETP activity and had no effect on LCAT activity. The mechanism responsible for these effects is unknown, but could involve the prevention of radical-induced damage to CETP by vitamin E. Coronary Artery Dis 9:257–264