Glucose Metabolism Is Required for Oxidized LDL–Induced Macrophage Survival

Abstract

Objective— Oxidized low-density lipoprotein (oxLDL) induces survival of colony stimulating factor-1 (CSF-1)-dependent macrophages in vitro. Because atherosclerotic lesion–associated macrophages take up large amounts of glucose, we investigated whether, and how, oxLDL promotes glucose uptake and how glucose metabolism regulates oxLDL-induced macrophage survival. Methods and Results— OxLDL-induced macrophage survival required glucose metabolism. OxLDL stimulated 2 phases of glucose uptake, namely acute and chronic, which required PI3K but not MEK1/2 activity. PI3K appeared to regulate glucose transport via glucose transporter affinity and/or mobilization. OxLDL also maintained levels of the prosurvival proteins, Bcl-2 and Bcl-x L , after CSF-1 had been removed through a combination of mechanisms including transcription, translation, and protein stabilization. Significantly, inhibition of glucose metabolism reduced Bcl-2 and Bcl-x L protein levels. MEK1/2 and PI3K activities were also required for oxLDL-induced Bcl-2 and Bcl-x L mRNA upregulation. Conclusions— These results suggest that oxLDL enhances macrophage survival in the absence of CSF-1 by inducing PI3K-dependent glucose uptake, which is metabolized to maintain Bcl-2 and Bcl-x L protein levels.