Cellular Cholesterol Efflux Mediated by Cyclodextrins (*)
- Elisabeth P. C. Kilsdonk(1)(§),
- Patricia G. Yancey(1),
- Genevieve W. Stoudt(1),
- Faan Wen Bangerter(2),
- William J. Johnson(1),
- Michael C. Phillips(1) and
- George H. Rothblat(1)(¶)
- From the (1) Department of Biochemistry, Medical College of Pennsylvania and Hahnemann University, Philadelphia, Pennsylvania 19129 and
- (2) Pfizer Central Research, Groton, Connecticut 06340
- ¶ To whom correspondence and reprint requests should be addressed: Dept. of Biochemistry, Medical College of Pennsylvania and Hahnemann University, 2900 Queen Lane, Philadelphia, PA 19129. Tel.: 215-991-8308; Fax: 215-843-8849.
Abstract
In this study, we compared cholesterol efflux mediated by either high density lipoproteins (HDL3) or β-cyclodextrins, cyclic oligosaccharides that are able to dissolve lipids in their hydrophobic core. β-Cyclodextrin, 2-hydroxypropyl-β-cyclodextrin, and methyl-β-cyclodextrin at 10 mM induced the release of 50-90% of L-cell [3H]cholesterol after 8 h of incubation, with a major portion of this cholesterol being released in the first 1-2 h of incubation. The cholesterol efflux kinetics are different if cells are incubated with HDL3, which induces a relatively constant rate of release of cholesterol throughout an 8-h incubation. Cholesterol efflux to cyclodextrins was much greater than phospholipid release. To test the hypothesis that maximal efflux rate constants for a particular cell are independent of the type of acceptor, we estimated the maximal rate constants for efflux (Vmax) of cellular cholesterol from L-cells, Fu5AH cells, and GM3468A fibroblasts. The rate constant for HDL3-mediated efflux varied among cell lines in the order Fu5AH > L-cells > fibroblasts. However, these differences were not evident when cyclodextrins were used as cholesterol acceptors. The estimated Vmax values for cyclodextrin-mediated efflux were 3.5-70-fold greater than for HDL3 for the three cell lines. The very high efficiency of cyclodextrins in stimulating cell cholesterol efflux suggests that these compounds can be used in two general ways for studies of atherosclerosis: 1) as research tools to probe mechanisms of cholesterol transport and aspects of membrane structure or 2) as potential pharmacological agents that could modify in vivo cholesterol metabolism and influence the development of the atherosclerotic plaque.
Footnotes
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↵§ Supported by the Niels Stensen Foundation, Amsterdam, The Netherlands and by an International Research Fellowship from the American Heart Association.
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↵* This research was funded by Program Project Grant HL22633 and Training Grant HL07443 (to P. Y.) from the National Institutes of Health. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 The abbreviations used are:
- HDL
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high density lipoprotein
- DMEM
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Dulbecco's modified Eagle's medium
- MEM
-
Eagle's minimum essential medium
- FBS
-
fetal bovine serum
- βCD
-
β-cyclodextrin
- MβCD
-
methyl-β-cyclodextrin
- 2OHpβCD
-
2-hydroxypropyl-β-cyclodextrin.
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- Received April 11, 1995.
- Revision received May 17, 1995.
