Ethyl pyruvate inhibits oxidation of LDL in vitro and attenuates oxLDL toxicity in EA.hy926 cells.

Christine Rossmann,Eva Maria Bernhart,Martin Koestenberger,Erwin Tafeit,Gerhard Ledinski,Seth Hallström,Margret Paar,Wolfgang Sattler,Christoph Nusshold,Gerhard Cvirn,Gianfranco Pintus

doi:10.1371/journal.pone.0191477

Christine Rossmann, Eva Maria Bernhart + Show 9 more

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https://doi.org/10.1371/journal.pone.0191477

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Journal: PloS one	Publication Date: Jan 25, 2018
Citations: 8	License type: CC BY 4.0

Affiliation: Medical University of Graz

Abstract

BackgroundEthyl pyruvate (EP) exerts anti-inflammatory and anti-oxidative properties. The aim of our study was to investigate whether EP is capable of inhibiting the oxidation of LDL, a crucial step in atherogenesis. Additionally, we examined whether EP attenuates the cytotoxic effects of highly oxidized LDL in the human vascular endothelial cell line EA.hy926.MethodsNative LDL (nLDL) was oxidized using Cu2+ ions in the presence of increasing amounts of EP. The degree of LDL oxidation was quantified by measuring lipid hydroperoxide (LPO) and malondialdehyde (MDA) concentrations, relative electrophoretic mobilities (REMs), and oxidation-specific immune epitopes. The cytotoxicity of these oxLDLs on EA.hy926 cells was assessed by measuring cell viability and superoxide levels. Furthermore, the cytotoxicity of highly oxidized LDL on EA.hy926 cells under increasing concentrations of EP in the media was assessed including measurements of high energy phosphates (ATP).ResultsOxidation of nLDL using Cu2+ ions was remarkably inhibited by EP in a concentration-dependent manner, reflected by decreased levels of LPO, MDA, REM, oxidation-specific epitopes, and diminished cytotoxicity of the obtained oxLDLs in EA.hy926 cells. Furthermore, the cytotoxicity of highly oxidized LDL on EA.hy926 cells was remarkably attenuated by EP added to the media in a concentration-dependent manner reflected by a decrease in superoxide and an increase in viability and ATP levels.ConclusionsEP has the potential for an anti-atherosclerotic drug by attenuating both, the oxidation of LDL and the cytotoxic effect of (already formed) oxLDL in EA.hy926 cells. Chronic administration of EP might be beneficial to impede the development of atherosclerotic lesions.

Highlights

Oxidation of low-density lipoprotein (LDL) is a central element in the development of atherosclerosis [1]
Oxidation of Native LDL (nLDL) using Cu2+ ions was remarkably inhibited by Ethyl pyruvate (EP) in a concentrationdependent manner, reflected by decreased levels of lipid hydroperoxide (LPO), MDA, relative electrophoretic mobilities (REMs), oxidation-specific epitopes, and diminished cytotoxicity of the obtained oxidized LDL (oxLDL) in EA.hy926 cells
The cytotoxicity of highly oxidized LDL on EA.hy926 cells was remarkably attenuated by EP added to the media in a concentration-dependent manner reflected by a decrease in superoxide and an increase in viability and ATP levels

Summary

Introduction

Oxidation of low-density lipoprotein (LDL) is a central element in the development of atherosclerosis [1]. In the subendothelial space of arterial sites, nLDL can become subject to oxidation by mechanisms involving free radicals and/or lipoxygenases [2]. The resulting oxidized form of nLDL, oxLDL, contains, i.a., malondialdehyde (MDA) and 4-hydroxynonenal (HNE), which have been shown to exert prominent cytotoxic effects on endothelial cells, a prerequisite for the pathogenesis of atherosclerosis [3, 4]. Drugs capable of suppressing oxidation of LDL possess anti-atherosclerotic properties. Tawadrous et al have shown that EP is capable of suppressing lipid peroxidation: Treatment with EP attenuated hepatic MDA formation in rats subjected to oxidative stress [7]. Ethyl pyruvate (EP) exerts anti-inflammatory and anti-oxidative properties. We examined whether EP attenuates the cytotoxic effects of highly oxidized LDL in the human vascular endothelial cell line EA.hy926

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