Reverse cholesterol transport in mice expressing simian cholesteryl ester transfer protein

The role of cholesteryl ester transfer protein (CETP) in atherogenesis remains ambiguous, as both pro and antiatherogenic effects have been described. Expression of CETP increases HDL-cholesteryl ester turnover, but there is no direct evidence whether CETP mobilizes cholesterol in vivo. The rate of cholesterol removal injected into a leg muscle as cationized low density lipoprotein (cat-LDL) was compared in CETP transgenic and control mice. Four days after injection the exogenous cholesterol mass retained in muscle was 65% in CETP transgenic and 70% of injected dose in controls; it decreased to 52–54% by day 8 and negligible amounts remained on day 28. The cat-LDL was labeled with either 3H-cholesterol oleate (3H-CE) or 3H-cholesteryl oleoyl ether (3H-COE), a nonhydrolyzable analog of 3H-CE. After injection of 3H-CE cat-LDL, clearance of 3H-cholesterol had a t1/2 of 4 days between day 4 and 8 but there was little loss of 3H-COE between day 4 and 51. Liver radioactivity on day 4 was 1.7% in controls and 3.4% in CETP transgenics; it was 2.8 and 4.6%, respectively, on day 8. 3H-COE in liver accounted for 60% of label in CETP transgenics. In conclusion, high levels of plasma CETP in mice do not enhance reverse cholesterol transport in vivo but may act on extracellularly located cholesteryl ester.