HDL Proteome in Hemodialysis Patients: A Quantitative Nanoflow Liquid Chromatography-Tandem Mass Spectrometry Approach

Alain Mangé,Bernard Canaud,Aurélie Goux,Thierry Maudelonde,Jean-Paul Cristol,Jérôme Solassol,Laure Patrier,Stéphanie Badiou,Partha Mukhopadhyay

doi:10.1371/journal.pone.0034107

Abstract

Aside from a decrease in the high-density lipoprotein (HDL) cholesterol levels, qualitative abnormalities of HDL can contribute to an increase in cardiovascular (CV) risk in end-stage renal disease (ESRD) patients undergoing chronic hemodialysis (HD). Dysfunctional HDL leads to an alteration of reverse cholesterol transport and the antioxidant and anti-inflammatory properties of HDL. In this study, a quantitative proteomics approach, based on iTRAQ labeling and nanoflow liquid chromatography mass spectrometry analysis, was used to generate detailed data on HDL-associated proteins. The HDL composition was compared between seven chronic HD patients and a pool of seven healthy controls. To confirm the proteomics results, specific biochemical assays were then performed in triplicate in the 14 samples as well as 46 sex-matched independent chronic HD patients and healthy volunteers. Of the 122 proteins identified in the HDL fraction, 40 were differentially expressed between the healthy volunteers and the HD patients. These proteins are involved in many HDL functions, including lipid metabolism, the acute inflammatory response, complement activation, the regulation of lipoprotein oxidation, and metal cation homeostasis. Among the identified proteins, apolipoprotein C-II and apolipoprotein C-III were significantly increased in the HDL fraction of HD patients whereas serotransferrin was decreased. In this study, we identified new markers of potential relevance to the pathways linked to HDL dysfunction in HD. Proteomic analysis of the HDL fraction provides an efficient method to identify new and uncharacterized candidate biomarkers of CV risk in HD patients.

Highlights

In the general population, a decrease in high-density lipoprotein (HDL) cholesterol and/or dysfunctional HDL is recognized as an important risk factor in cardiovascular (CV) diseases [1,2]
We investigated the HDL proteome in HD patients who are considered to have a high risk for CV diseases
Multidimensional nano-LC/MS/MS was used for the analysis of the HDL samples, which were labeled with isobaric mass tags to identify the proteins that were differentially expressed between the HDL fractions of the HD patients and the healthy volunteers

Summary

Introduction

A decrease in high-density lipoprotein (HDL) cholesterol and/or dysfunctional HDL is recognized as an important risk factor in cardiovascular (CV) diseases [1,2]. Several studies have focused on the protective effects of HDL on lowdensity lipoprotein (LDL) oxidation in the arterial wall [3]. HDL is recognized to protect against plaque formation and progression, in part, through the transport of cholesterol from the peripheral tissues to the liver [4]. The other biological activities of HDL are related to their protein component and are vital in the atheroprotective effects of HDL. Of particular importance are the potent antioxidative and anti-inflammatory activities of HDL, which can directly inhibit LDL oxidation and LDL-induced monocyte infiltration [1,3]. In chronic and acute inflammation, HDL can have pro-oxidative and proinflammatory properties [1,5,6,7]

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