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Journal of Lipid Research, Vol. 45, 1242-1255, July 2004
Copyright © 2004 by American Society for Biochemistry and Molecular Biology

Postprandial chylomicrons

Byung-Hong Chung^1,*, Ping Liang^*, Steve Doran^*, B. H. Simon Cho and Frank Franklin

^* Atherosclerosis Research Unit, Departments of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294
Pediatrics, University of Alabama at Birmingham, Birmingham, AL 35294
Moore Heart Research Foundation, University of Illinois, Champaign, IL

¹ To whom correspondence should be addressed. e-mail: bhchung{at}uab.edu

We examined whether postprandial (PP) chylomicrons (CMs) can serve as vehicles for transporting cholesterol from endogenous cholesterol-rich lipoprotein (LDL+HDL) fractions and cell membranes to the liver via lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP) activities. During incubation of fresh fasting and PP plasma containing [³H]cholesteryl ester (CE)-labeled LDL+HDL, both CMs and VLDL served as acceptors of [³H]CE or cholesterol from LDL+HDL. The presence of CMs in PP plasma suppressed the ability of VLDL to accept [³H]CE from LDL+HDL. In reconstituted plasma containing an equivalent amount of triglycerides from isolated VLDL or CMs, a CM particle was about 40 times more potent than a VLDL particle in accepting [³H]CE or cholesterol from LDL+HDLs. When incubated with red blood cells (RBCs) as a source for cell membrane cholesterol, the cholesterol content of CMs, VLDL, LDL, and HDL in PP plasma increased by 485%, 74%, 13%, and 30%, respectively, via LCAT and CETP activities. The presence of CMs in plasma suppressed the ability of endogenous lipoproteins to accept cholesterol from RBCs.

Our data suggest that PP CMs may play an important role in promoting reverse cholesterol transport in vivo by serving as the preferred ultimate vehicle for transporting cholesterol released from cell membranes to the liver via LCAT and CETP.

Abbreviations: apoB, apolipoprotein B; CE, cholesteryl ester; CETP, cholesteryl ester transfer protein; CM, chylomicron; CVD, cardiovascular disease; GCRC, General Clinical Research Center; LDL+HDL, cholesterol-rich lipoprotein; PP, postprandial; RBC, red blood cell; RCT, reverse cholesterol transport; TG, triglyceride; TRL, triglyceride-rich lipoprotein; UC, unesterified cholesterol

Supplementary key words postprandial lipemia • cholesteryl ester transfer protein • lecithin:cholesterol acyltransferase • cholesterol-rich lipoproteins

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