Inhibition of Niemann-Pick C1-Like 1 by Ezetimibe Reduces Dietary 5β,6β-Epoxycholesterol Absorption in Rats
Oxycholesterols (OCs) are produced from cholesterol by oxidation of the steroidal backbone and side-chain. OCs are present in blood and evidence suggests their involvement in disease development and progression. However, limited information is available regarding the absorption mechanisms and relative absorption rates of dietary OCs. Although ezetimibe is known to inhibit intestinal cholesterol absorption via Niemann-Pick C1-Like 1 (NPC1L1), whether it also inhibits dietary OC absorption is unclear.
We investigated the effects of ezetimibe on OC absorption in rats fed an OC-rich diet containing 10 different OCs. We collected lymphatic fluid using permanent cannulation of the thoracic duct and quantified OC levels.
Ezetimibe treatment significantly reduced the apparent absorption of 5β,6β-epoxycholesterol (5,6β-epoxy) and its levels in the proximal intestinal mucosa in OC-fed rats. Using in silico analyses, the binding energy of NPC1L1 N-terminal domain (NPC1L1-NTD) and 5,6β-epoxy was found to be similar to that of NPC1L1-NTD and cholesterol, suggesting that polar uncharged amino acids located in the steroidal part of 5,6β-epoxy were involved.
Our results indicate that ezetimibe-mediated inhibition of dietary OC absorption varies depending on the specific OC, and only the absorption of 5,6β-epoxy is significantly reduced.
KeywordsEzetimibe Dietary oxycholesterols Intestinal absorption Lymphatic lipid transport Permanent thoracic lymph duct cannulation
- Niemann-Pick C1-Like 1
The authors thank Editage (www.editage.jp) for English language editing.
B.S. wrote the manuscript. B.S., Y.F., Y. N., A.K., and H.O. participated in the experimental work and collected and analyzed data. B.S., K.I., and M.S. contributed to the study design, supervised the study, and commented on the manuscript.
This study was supported by JSPS KAKENHI (Grant Number 23780138 (to B.S.) and 25870507 (to B.S.)), Bayer Yakuhin, Ltd. (Osaka, Japan) (to M.S.), and the Collaborative Research of Tropical Biosphere Research Center, University of the Ryukyus (Okinawa, Japan) (to B.S.). The cost of English language editing was supported in part by Kyushu University Research Activity Support Program “English/Japanese Proofreading Expenses Support” (to B.S.).
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
The handling and euthanasia of all animals were carried out in accordance with nationally prescribed guidelines, and ethical approval for the studies was granted by the Animal Care and Use Committee of Kyushu University. The authorization number was A24-034-2. This article does not contain any studies with human participants performed by any of the authors.
Informed consent is not applicable in this article.
Consent for Publication
All authors have approved the submission for publication of this study.
- 19.Carey MC, Hernell O. Digestion and absorption of fat. Semin Gastrointest Dis. 1992;3:189–208.Google Scholar
- 23.Bang HJ, Arakawa C, Takada M, Sato M, Imaizumi K. A comparison of the potential unfavorable effects of oxycholesterol and oxyphytosterol in mice: different effects, on cerebral 24S-hydroxychoelsterol and serum triacylglycerols levels. Biosci Biotechnol Biochem. 2008;72:3128–33.CrossRefGoogle Scholar
- 27.Sánchez R, Sali A. Comparative protein structure modeling. Introduction and practical examples with modeller. Methods Mol Biol. 2000;143:97–129.Google Scholar
- 34.Yanai H. Statcel 3–the useful add-in software forms on excel, 3rd ed. Tokyo: OMS; 2011.Google Scholar
- 35.Bosner MS, Lange LG, Stenson WF, Ostlund RE Jr. Percent cholesterol absorption in normal women and men quantified with dual stable isotopic tracers and negative ion mass spectrometry. J Lipid Res. 1999;40:302–8.Google Scholar
- 39.Aringer L, Eneroth P. Formation and metabolism in vitro of 5,6-epoxides of cholesterol and beta-sitosterol. J Lipid Res. 1974;15:389–98.Google Scholar
- 40.Peng SK, Taylor CB, Tham P, Werthessen NT, Mikkelson B. Effect of auto-oxidation products from cholesterol on aortic smooth muscle cells: an in vitro study. Arch Pathol Lab Med. 1978;102:57–61.Google Scholar
- 42.Sevanian A, Berliner J, Peterson H. Uptake, metabolism, and cytotoxicity of isomeric cholesterol-5,6-epoxides in rabbit aortic endothelial cells. J Lipid Res. 1991;32:147–55.Google Scholar
- 45.Sato K, Nakano K, Katsuki S, et al. Dietary cholesterol oxidation products accelerate plaque destabilization and rupture associated with monocyte infiltration/activation via the MCP-1-CCR2 pathway in mouse brachiocephalic arteries: therapeutic effects of ezetimibe. J Atheroscler Thromb. 2012;19:986–98.CrossRefGoogle Scholar