PPARβ in macrophages and atherosclerosis.

Macrophages are central cells in the genesis and development of atherosclerosis, one of the major causes of cardiovascular diseases. Macrophages take up lipids (mainly cholesterol and triglycerides) from lipoproteins thus transforming into foam cells. Moreover, through the efflux pathway, macrophages are the main actors of the elimination of excessive tissue cholesterol toward extra-cellular acceptors. Macrophages participate in the control of inflammation by displaying different functional phenotypes, from the M1 pro-inflammatory to the M2 anti-inflammatory state. The nuclear receptor Peroxisome Proliferator-Activated Receptor (PPAR)β (also called PPARδ or PPARβ/δ) is expressed in macrophages where it plays a different role in the control of lipid metabolism, inflammation and phagocytosis of apoptotic cells. This review will summarize our current understanding of how PPARβ regulates macrophage biology and its impact on atherosclerosis. Differences between studies and species-specific macrophage gene regulation will be discussed.