This study aimed to investigate whether cholesteryl ester transfer protein inhibition promotes in vivo reverse cholesterol transport in dyslipidemic hamsters.Methods and Results—
In vivo reverse cholesterol transport was measured after an intravenous injection of 3H-cholesteryl-oleate–labeled/oxidized low density lipoprotein particles (3H-oxLDL), which are rapidly cleared from plasma by liver-resident macrophages for further 3H-tracer egress in plasma, high density lipoprotein (HDL), liver, and feces. A first set of hamsters made dyslipidemic with a high-fat and high-fructose diet was treated with vehicle or torcetrapib 30 mg/kg (TOR) over 2 weeks. Compared with vehicle, TOR increased apolipoprotein E–rich HDL levels and significantly increased 3H-tracer appearance in HDL by 30% over 72 hours after 3H-oxLDL injection. However, TOR did not change 3H-tracer recovery in liver and feces, suggesting that uptake and excretion of cholesterol deriving from apolipoprotein E-rich HDL is not stimulated. As apoE is a potent ligand for the LDL receptor, we next evaluated the effects of TOR in combination with the LDL-lowering drug berberine, which upregulates LDL receptor expression in dyslipidemic hamsters. Compared with TOR alone, treatment with TOR+berberine 150 mg/kg resulted in lower apolipoprotein E–rich HDL levels. After 3H-oxLDL injection, TOR+berberine significantly increased 3H-tracer appearance in fecal cholesterol by 109%.Conclusion—
Our data suggest that cholesteryl ester transfer protein inhibition alone does not stimulate reverse cholesterol transport in dyslipidemic hamsters and that additional effects mediated by the LDL-lowering drug berberine are required to upregulate this process.