Nuclear receptors in macrophage biology: At the crossroads of lipid metabolism and inflammation

Macrophages are essential modulators of lipid metabolism and the innate immune system. Lipid and inflammatory pathways induced in activated macrophages are central to the pathogenesis of human diseases including atherosclerosis. Recent work has shown that expression of genes involved in lipid uptake and cholesterol efflux in macrophages is controlled by peroxisome proliferator-activated receptors (PPARs) and liver X receptors (LXRs). Other studies have implicated these same receptors in the modulation of macrophage inflammatory gene expression. Together, these observations position PPARs and LXRs at the crossroads of lipid metabolism and inflammation and suggest that these receptors may serve to integrate these pathways in the control of macrophage gene expression. In this review, we summarize recent work that has advanced our understanding of the roles of PPARs and LXRs in macrophage biology and discuss the implication of these results for cardiovascular physiology and disease.