Vitamin E Transfer from Lipid Emulsions to Plasma Lipoproteins: Mediation by Multiple Mechanisms |
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Authors: | M Hacquebard M Vandenbranden W J Malaisse J M Ruysschaert R J Deckelbaum Y A Carpentier |
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Affiliation: | (1) L. Deloyers Laboratory for Experimental Surgery, Université Libre de Bruxelles, Avenue J. Wybran 40, 1070 Brussels, Belgium;(2) Laboratory of Structure and Function of Biological Membranes-Center of Structural Biology and Bioinformatics, Université Libre de Bruxelles, Brussels, Belgium;(3) Institute of Human Nutrition, Columbia University, New York, USA |
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Abstract: | The present study determined alpha-tocopherol mass transfer from an alpha-tocopherol-rich emulsion to LDL and HDL, and assessed
the potential of different mechanisms to modulate alpha-tocopherol transfers. Emulsion particles rich in alpha-tocopherol
were incubated in vitro with physiological concentrations of LDL or HDL. The influence of plasma proteins was assessed by
adding human lipoprotein poor plasma (LPP) fraction with intact vs heat inactivated PLTP, or with a specific cholesteryl ester
transfer protein (CETP) inhibitor, or by adding purified PLTP or pig LPP which lacks CETP activity. After 4 h incubation in
absence of LPP, alpha-tocopherol content was increased by ~80% in LDL and ~160% in HDL. Addition of LPP markedly enhanced
alpha-tocopherol transfer leading to 350–400% enrichment in LDL or HDL at 4 h. Higher (~10 fold) enrichment was achieved after
20 h incubation with LPP. Facilitation of alpha-tocopherol transfer was (i) more than 50% higher with human vs pig LPP (despite
similar PLTP phospholipid transfer activity), (ii) reduced by specific CETP activity inhibition, (iii) not fully suppressed
by heat inactivation, and (iv) not restored by purified PLTP. In conclusion, alpha-tocopherol content in LDL and HDL can be
markedly raised by rapid transfer from an alpha-tocopherol-rich emulsion. Our results indicate that alpha-tocopherol mass
transfer between emulsion particles and lipoproteins is mediated by more than one single mechanism and that this transfer
may be facilitated not only by PLTP but likely also by other plasma proteins such as CETP. |
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Keywords: | Vitamin E Alpha-tocopherol mass transfer Lipid emulsions LDL HDL PLTP CETP |
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