Hypoxia-Inducible Factor-1α Expression in Macrophages Promotes Development of Atherosclerosis

<jats:sec> <jats:title>Objective—</jats:title> <jats:p>Atherosclerotic lesions contain hypoxic areas, but the pathophysiological importance of hypoxia is unknown. Hypoxia-inducible factor-1α (HIF-1α) is a key transcription factor in cellular responses to hypoxia. We investigated the hypothesis that HIF-1α has effects on macrophage biology that promotes atherogenesis in mice.</jats:p> </jats:sec> <jats:sec> <jats:title>Approach and Results—</jats:title> <jats:p> Studies with molecular probes, immunostaining, and laser microdissection of aortas revealed abundant hypoxic, HIF-1α–expressing macrophages in murine atherosclerotic lesions. To investigate the significance of macrophage HIF-1α, <jats:italic>Ldlr</jats:italic> <jats:sup>−/−</jats:sup> mice were transplanted with bone marrow from mice with HIF-1α deficiency in the myeloid cells or control bone marrow. The HIF-1α deficiency in myeloid cells reduced atherosclerosis in aorta of the <jats:italic>Ldlr</jats:italic> <jats:sup>−/−</jats:sup> recipient mice by ≈72% ( <jats:italic>P</jats:italic> =0.006). </jats:p> <jats:p>In vitro, HIF-1α–deficient macrophages displayed decreased differentiation to proinflammatory M1 macrophages and reduced expression of inflammatory genes. HIF-1α deficiency also affected glucose uptake, apoptosis, and migratory abilities of the macrophages.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions—</jats:title> <jats:p>HIF-1α expression in macrophages affects their intrinsic inflammatory profile and promotes development of atherosclerosis.</jats:p> </jats:sec>