Effect of dietary cholesterol oxidation products on the plasma clearance of chylomicrons in the rat.

Oxidized cholesterols in the diet have been shown to exacerbate arterial cholesterol deposition and the development of atherosclerosis in animal models. Dietary oxidized cholesterols are absorbed through the intestine and incorporated into lymph chylomicrons. The aim of this study was to investigate the effect of oxidized cholesterols on the metabolism of nascent chylomicrons in vivo. It was shown that oxidized cholesterols markedly delay the clearance of chylomicrons from plasma compared to rats given TG alone. However, there was no difference in the clearance of chylomicrons containing oxidized cholesterols vs. purified cholesterol, although the presence of oxysterols did appear to exacerbate the removal of these particles from circulation. The impaired clearance of chylomicrons containing oxidized cholesterols was not due to impaired lipolysis and slower conversion to the remnant form. Moreover, the incorporation of oxidized cholesterols did not alter the hepatic or splenic uptake of chylomicrons compared to chylomicrons isolated from rats given purified cholesterol or TG alone. Collectively, the results of this study suggest that the exacerbated delay in clearance of chylomicron remnants enriched with oxysterols may be due to impaired uptake by tissues other than the liver and spleen. Apolipoprotein (apo) analysis showed that oxysterol incorporation reduced the apoE content and altered the apoC phenotype of chylomicrons, which may have an impact on the removal of chylomicron remnants from plasma. In conclusion, dietary oxysterols appear to have the potential to adversely affect chylomicron metabolism. Therefore, further investigations in humans are required to determine whether dietary oxidized cholesterols found in cholesterol-rich processed foods delay the clearance of postprandial remnants, which may contribute to and exacerbate the development of atherosclerosis.