Role of alternative macrophages in vascular calcification – AlMaVasCal
The ectopic deposition of calcium within the atherosclerotic plaques leads to the development of vascular calcification (VC), a complication for atherosclerosis disease. VC is a dynamic process that takes place by mechanisms similar of those of bone formation, implying both the osteoblasts (OTB) that generate bone matrix and the osteoclasts (OTC) which resemble to macrophages and are involved in bone resorption. Macrophages are versatile cells able to adapt their functional phenotype to the micro- environment. Indeed, at least two populations of macrophages have been described: the pro-inflammatory classically activated M1 macrophages and the alternative anti-inflammatory M2 macrophages. We have already reported that these alternative M2 macrophages are present in human atherosclerotic plaques, with specific localizations and functions, particularly with respect to cholesterol and iron handling as well as to phagocytic capacity of senescent cells. Moreover, our preliminary results also indicate that these M2 macrophages are abundantly present near the calcified areas of the atherosclerotic plaques. Interestingly, when differentiated in vitro in the presence of IL-4, these M2 macrophages express some OTC markers such as CA2 and CatK, but they also express some OTB markers, such as TNAP and BMP-2 . Moreover, their exact role in VC is still not defined. Our project aims at determine the function of alternative macrophages in VC and at identifying the molecular mechanisms behind their capacity to acquire both the OTC and OTB phenotypes by using human samples (cells and tissues) and applying global innovative technologies (transcriptomic analysis, mass spectrometry imaging and miRNA profiling).
Ex vivo, a molecular cartography of the alternative M2 macrophages enriched near the calcification zones will be generated in terms of expression of proteins, genes and metabolites. In vitro, these M2 macrophages will be cultured under conditions allowing the acquisition of the OTB phenotype, in the presence of calcifying medium, or the OTC phenotype, obtained by differentiating the cells in the presence of a mixture of RANKL/MCSF. The expression of specific markers for the OTB and OTC phenotypes will be measured (gene and protein) and functional tests will be setup to determine the capacity of the M2 macrophages in terms of calcium accumulation (for the OTB) or degradation of the bone matrix (for the OTC). Moreover, the impact of alternative macrophages on osteogenic properties of vascular smooth muscle cells, the other major cell type involved in the VC process together with macrophages will be determine by indirect co-culture experiments and assessed as variation of specific marker expression and functional activities. Finally, to identify the molecular switcher of the OTC and OTB phenotypes in macrophages, different approaches will be applied covering the study of target genes (identified on the basis of literature available data) and global studies on transcriptomic and miRNA profiling.
This project will be done in collaboration between the team of Prof. G. Chinetti in Nice and the group of Prof. B.Staels in Lille. These two researchers have already worked together for almost 18 years and have been pioneers in the study of the macrophage sub-populations in human atherosclerotic lesions. This constitutes a guarantee for the good execution of the current project and the success of this proposal.
We believe that our project will have important repercussions on the scientific community of the VC. We will identify the novel potential roles of M2 macrophages in VC. This is a crucial step because we need to understand in depth the molecular and cellular mechanisms involved in the VC in order to be able to modulate them and to discover novel therapeutics target to control the calcium deposition within atherosclerotic lesions.
Madame Giulia Chinetti (Inserm UMR1081, Université de Nice-Sophia Antipolis, CHU de Nice)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
Inserm UMR1081, Université de Nice-Sophia Antipolis, CHU de Nice
UMR 1011 INSERM Inserm UMR 1011, Université de Lille, Institut Pasteur de Lille
Help of the ANR 544,752 euros
Beginning and duration of the scientific project: December 2016 - 36 Months