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Mediators of Inflammation
Volume 2016, Article ID 8249476, 20 pages
http://dx.doi.org/10.1155/2016/8249476
Research Article

Myeloperoxidase-Oxidized LDLs Enhance an Anti-Inflammatory M2 and Antioxidant Phenotype in Murine Macrophages

1URBC-Narilis, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium
2UMBD, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium
3Laboratory of Experimental Medicine (ULB 222 Unit), Université Libre de Bruxelles, CHU-Charleroi, ISPPC Hôpital Vésale, Montigny-Le-Tilleul, Belgium
4Therapeutic Chemistry, ULB (Campus de la Plaine) CP205/05, boulevard du Triomphe, Brussels, Belgium

Received 25 April 2016; Revised 28 July 2016; Accepted 2 August 2016

Academic Editor: Michal A. Rahat

Copyright © 2016 Valérie Pireaux et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Macrophages and oxidized LDLs play a key role in atherogenesis but their heterogeneity has been neglected up to now. Macrophages are prone to polarization and subsets of polarized macrophages have been described in atheromas. LDLs can be oxidized not only chemically by copper (Ox-LDLs) but also enzymatically by myeloperoxidase (MpOx-LDLs) resulting in oxidized LDLs poor in lipid peroxides. The effects of physiologically relevant myeloperoxidase-oxidized LDLs on macrophage polarization or on polarized macrophages remain largely unknown. In this study, the effects of LDLs on macrophage polarization were investigated by monitoring the expression of M1 and M2 genes following stimulation with native LDLs, Ox-LDLs, or MpOx-LDLs in RAW 264.7 cells. Except for MRC1, which is induced only by Ox-LDLs, MpOx-LDLs induced an overexpression of most of the selected marker genes at the mRNA level. MpOx-LDLs also modulate marker gene expression in polarized macrophages favoring notably anti-inflammatory Arg1 expression in M2 cells and also in the other phenotypes. Noteworthy, MpOx-LDLs were the most efficient to accumulate lipids intracellularly in (un)polarized macrophages whatever the phenotype. These data were largely confirmed in murine bone marrow-derived macrophages. Our data suggest that MpOx-LDLs were the most efficient to accumulate within cells and to enhance an anti-inflammatory and antioxidant phenotype in M2 cells and also in the other macrophage phenotypes.