title: Phenotypic modulation of macrophages in response to plaque lipids.
abstract: OBJECTIVE
  The accumulation of macrophages in the vascular wall is a hallmark of atherosclerosis. The biological properties of atherosclerotic plaque macrophages determine lesion size, composition, and stability. In atherosclerotic plaques, macrophages encounter a microenvironment that comprises a variety of lipid oxidation products, each of which has diverse biological effects. In this review, we summarize recent advances in our understanding of the effects of plaque lipids on macrophage phenotypic polarization.
  
  
  RESULTS
  Atherosclerotic lesions in mice and in humans contain various macrophage phenotypes, which play different roles in mediating inflammation, the clearance of dead cells, and possibly resolution. Macrophages alter their phenotype and biological function in response to plaque lipids through the upregulation of specific sets of genes. Interaction of oxidized lipids with pattern recognition receptors and activation of the inflammasome by cholesterol crystals drive macrophages toward an inflammatory M1 phenotype. A new phenotype, Mox, develops when oxidized phospholipids activate stress response genes via Nrf2. Other lipid mediators such as nitrosylated-fatty acids and omega-3 fatty acid-derived products polarize plaque macrophages toward anti-inflammatory and proresolving phenotypes.
  
  
  CONCLUSIONS
  A deeper understanding of how lipids that accumulate in atherosclerotic plaques affect macrophage phenotype and function and thus atherosclerotic lesion development and stability will help to devise novel strategies for intervention.
authors.affiliation: Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA.
authors.forename: Samantha
authors.initials: S
authors.lastname: Adamson
authors.forename: Norbert
authors.initials: N
authors.lastname: Leitinger
mesh_terms: D000818:Animals; D050197:Atherosclerosis / Q000276:immunology*; D006801:Humans; D007249:Inflammation / Q000276:immunology; D050356:Lipid Metabolism; D008264:Macrophages / Q000276:immunology*; D010084:Oxidation-Reduction