Cholesterol metabolites exported from human brain

Luigi Iuliano, Peter J Crick, Chiara Zerbinati, Luigi Tritapepe, Jonas Abdel-Khalik, Marc Poirot, Yuqin Wang, William J Griffiths, Luigi Iuliano, Peter J Crick, Chiara Zerbinati, Luigi Tritapepe, Jonas Abdel-Khalik, Marc Poirot, Yuqin Wang, William J Griffiths

Abstract

The human brain contains approximately 25% of the body's cholesterol. The brain is separated from the circulation by the blood brain barrier. While cholesterol will not passes this barrier, oxygenated forms of cholesterol can cross the barrier. Here by measuring the difference in the oxysterol content of blood plasma in the jugular vein and in a forearm vein by mass spectrometry (MS) we were able to determine the flux of more than 20 cholesterol metabolites between brain and the circulation. We confirm that 24S-hydroxycholesterol is exported from brain at a rate of about 2-3mg/24h. Gas chromatography (GC)-MS data shows that the cholesterol metabolites 5α-hydroxy-6-oxocholesterol (3β,5α-dihydroxycholestan-6-one), 7β-hydroxycholesterol and 7-oxocholesterol, generally considered to be formed through reactive oxygen species, are similarly exported from brain at rates of about 0.1, 2 and 2mg/24h, respectively. Although not to statistical significance both GC-MS and liquid chromatography (LC)-MS methods indicate that (25R)26-hydroxycholesterol is imported to brain, while LC-MS indicates that 7α-hydroxy-3-oxocholest-4-enoic acid is exported from brain.

Keywords: 24S-hydroxycholesterol; GC–MS; LC–MS; Oxysterol.

Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Figures

Graphical abstract
Graphical abstract
Fig. 1
Fig. 1
Flux of sterols out from (positive value) and into (negative value) brain. Plasma concentrations of sterols in the jugular vein and a forearm vein taken from coronary heart disease patients (n = 18) undergoing on-pump myocardial revascularization surgery were measured by GC–MS. The flux of sterol out from and into brain was calculated based on jugular vein and forearm vein differences assuming a flow of plasma to the brain of 450 mL/min. Paired sample t tests were performed. ∗P < 0.05; ∗∗P < 0.01.
Fig. 2
Fig. 2
Flux of sterols out from (positive value) and into (negative value) brain. Plasma concentrations of sterols in the jugular vein and a forearm vein taken from coronary heart disease patients (n = 18) undergoing on-pump myocardial revascularization surgery were measured by LC–MS. The flux of sterol out from and into brain was calculated based on jugular vein and forearm vein differences assuming a flow of plasma to the brain of 450 mL/min. Individual data points are represented by filled circles. Mean values are indicated by a solid bar. Paired sample t tests were performed. ∗P < 0.05; ∗∗P < 0.01. Data for 7α,25-diHCO and 7α,26-diHCO has been reported previously . See Supporting information Table S2 for a full list of all compound abbreviations.
Fig. 3
Fig. 3
Cholesterol metabolism in brain. Cholesterol metabolites leaving and entering brain are indicated by arrows. Enzymes involved in cholesterol metabolism are shown. The metabolites within the boxed inset are likely formed through ROS. aPresent work. Formed via ROS. bFrom reference . cFrom Ref. . dFrom Ref. . eFrom Refs. [3–6] and present work.

References

    1. Dietschy J.M., Turley S.D. Thematic review series: brain lipids. Cholesterol metabolism in the central nervous system during early development and in the mature animal. J Lipid Res. 2004;45:1375–1397.
    1. Björkhem I., Meaney S. Brain cholesterol: long secret life behind a barrier. Arterioscler Thromb Vasc Biol. 2004;24:806–815.
    1. Lütjohann D., Breuer O., Ahlborg G., Nennesmo I., Sidén A., Diczfalusy U., Björkhem I. Cholesterol homeostasis in human brain: evidence for an age-dependent flux of 24S-hydroxycholesterol from the brain into the circulation. Proc Natl Acad Sci USA. 1996;93:9799–9804.
    1. Björkhem I., Lütjohann D., Diczfalusy U., Ståhle L., Ahlborg G., Wahren J. Cholesterol homeostasis in human brain: turnover of 24S-hydroxycholesterol and evidence for a cerebral origin of most of this oxysterol in the circulation. J Lipid Res. 1998;39:1594–1600.
    1. Björkhem I. Crossing the barrier: oxysterols as cholesterol transporters and metabolic modulators in the brain. J Intern Med. 2006;260:493–508.
    1. Heverin M., Meaney S., Lütjohann D., Diczfalusy U., Wahren J., Björkhem I. Crossing the barrier: net flux of 27-hydroxycholesterol into the human brain. J Lipid Res. 2005;46:1047–1052.
    1. Fahy E., Subramaniam S., Brown H.A., Glass C.K., Merrill A.H., Jr, Murphy R.C., Raetz C.R., Russell D.W., Seyama Y., Shaw W., Shimizu T., Spener F., van Meer G., VanNieuwenhze M.S., White S.H., Witztum J.L., Dennis E.A. A comprehensive classification system for lipids. J Lipid Res. 2005;46:839–861.
    1. Heverin M., Bogdanovic N., Lütjohann D., Bayer T., Pikuleva I., Bretillon L., Diczfalusy U., Winblad B., Björkhem I. Changes in the levels of cerebral and extracerebral sterols in the brain of patients with Alzheimer’s disease. J Lipid Res. 2004;45:186–193.
    1. Meaney S., Heverin M., Panzenboeck U., Ekström L., Axelsson M., Andersson U., Diczfalusy U., Pikuleva I., Wahren J., Sattler W., Björkhem I. Novel route for elimination of brain oxysterols across the blood-brain barrier: conversion into 7alpha-hydroxy-3-oxo-4-cholestenoic acid. J Lipid Res. 2007;48:944–951.
    1. Arca M., Natoli S., Micheletta F., Riggi S., Di Angelantonio E., Montali A., Antonini T.M., Antonini R., Diczfalusy U., Iuliano L. Increased plasma levels of oxysterols, in vivo markers of oxidative stress, in patients with familial combined hyperlipidemia: reduction during atorvastatin and fenofibrate therapy. Free Radic Biol Med. 2007;42:698–705.
    1. Björkhem I. Five decades with oxysterols. Biochimie. 2013;95:448–454.
    1. Griffiths W.J., Crick P.J., Wang Y. Methods for oxysterol analysis: past, present and future. Biochem Pharmacol. 2013;86:3–14.
    1. Stiles A.R., Kozlitina J., Thompson B.M., McDonald J.G., King K.S., Russell D.W. Genetic, anatomic, and clinical determinants of human serum sterol and vitamin D levels. Proc Natl Acad Sci USA. 2014;111:E4006–E4014.
    1. Dzeletovic S., Breuer O., Lund E., Diczfalusy U. Determination of cholesterol oxidation products in human plasma by isotope dilution-mass spectrometry. Anal Biochem. 1995;225:73–80.
    1. Iuliano L., Micheletta F., Natoli S., Ginanni Corradini S., Iappelli M., Elisei W. Measurement of oxysterols and alpha-tocopherol in plasma and tissue samples as indices of oxidant stress status. Anal Biochem. 2003;312:217–223.
    1. Voisin M., Silvente-Poirot S., Poirot M. One step synthesis of 6-oxo-cholestan-3β,5α-diol. Biochem Biophys Res Commun. 2014;446:782–785.
    1. Nury T., Samadi M., Zarrouk A., Riedinger J.M., Lizard G. Improved synthesis and in vitro evaluation of the cytotoxic profile of oxysterols oxidized at C4 (4α- and 4β-hydroxycholesterol) and C7 (7-ketocholesterol, 7α- and 7β-hydroxycholesterol) on cells of the central nervous system. Eur J Med Chem. 2013;70:558–567.
    1. Griffiths W.J., Crick P.J., Wang Y., Ogundare M., Tuschl K., Morris A.A. Analytical strategies for characterization of oxysterol lipidomes: liver X receptor ligands in plasma. Free Radic Biol Med. 2013;59:69–84.
    1. Crick PJ, Bentley TW, Abdel-Khalik J, Matthews I, Clayton PT, Morris AA et al. Quantitative charge-tags for sterol and oxysterol analysis. Clin Chem. PMID:25512642 [Epub ahead of print].
    1. Pulfer M.K., Murphy R.C. Formation of biologically active oxysterols during ozonolysis of cholesterol present in lung surfactant. J Biol Chem. 2004;279:26331–26338.
    1. Iuliano L. Pathways of cholesterol oxidation via non-enzymatic mechanisms. Chem Phys Lipids. 2011;164:457–468.
    1. Miyoshi N., Iuliano L., Tomono S., Ohshima H. Implications of cholesterol autoxidation products in the pathogenesis of inflammatory diseases. Biochem Biophys Res Commun. 2014;446:702–708.
    1. Zhang Q., Powers E.T., Nieva J., Huff M.E., Dendle M.A., Bieschke J., Glabe C.G., Eschenmoser A., Wentworth P., Jr, Lerner R.A., Kelly J.W. Metabolite-initiated protein misfolding may trigger Alzheimer’s disease. Proc Natl Acad Sci USA. 2004;101:4752–4757.
    1. de Medina P., Paillasse M.R., Segala G., Poirot M., Silvente-Poirot S. Identification and pharmacological characterization of cholesterol-5,6-epoxide hydrolase as a target for tamoxifen and AEBS ligands. Proc Natl Acad Sci USA. 2010;107:13520–13525.
    1. Lund E.G., Guileyardo J.M., Russell D.W. CDNA cloning of cholesterol 24-hydroxylase, a mediator of cholesterol homeostasis in the brain. Proc Natl Acad Sci USA. 1999;96:7238–7243.
    1. Russell D.W. The enzymes, regulation, and genetics of bile acid synthesis. Annu Rev Biochem. 2003;72:137–174.
    1. Rose K., Allan A., Gauldie S., Stapleton G., Dobbie L., Dott K., Martin C., Wang L., Hedlund E., Seckl J.R., Gustafsson J.A., Lathe R. Neurosteroid hydroxylase CYP7B: vivid reporter activity in dentate gyrus of gene-targeted mice and abolition of a widespread pathway of steroid and oxysterol hydroxylation. J Biol Chem. 2001;276:23937–23944.
    1. de la Torre J.C. Is Alzheimer’s disease a neurodegenerative or a vascular disorder? Data, dogma, and dialectics. Lancet Neurol. 2004;3:184–190.

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