Testing the Role of Myeloid Cell Glucose Flux in Inflammation and Atherosclerosis

Summary: Inflammatory activation of myeloid cells is accompanied by increased glycolysis, which is required for the surge in cytokine production. Although in vitro studies suggest that increased macrophage glucose metabolism is sufficient for cytokine induction, the proinflammatory effects of increased myeloid cell glucose flux in vivo and the impact on atherosclerosis, a major complication of diabetes, are unknown. We therefore tested the hypothesis that increased glucose uptake in myeloid cells stimulates cytokine production and atherosclerosis. Overexpression of the glucose transporter GLUT1 in myeloid cells caused increased glycolysis and flux through the pentose phosphate pathway but did not induce cytokines. Moreover, myeloid-cell-specific overexpression of GLUT1 in LDL receptor-deficient mice was ineffective in promoting atherosclerosis. Thus, increased glucose flux is insufficient for inflammatory myeloid cell activation and atherogenesis. If glucose promotes atherosclerosis by increasing cellular glucose flux, myeloid cells do not appear to be the key targets. : Diabetes is associated with cardiovascular complications due to atherosclerosis, but the role of elevated glucose in this process is still uncertain. Nishizawa et al. now test the long-standing hypothesis that increased glucose in myeloid cells, important contributors to atherosclerosis, stimulates inflammatory activation and atherosclerosis. Although the glucose transporter GLUT1 was required for inflammatory activation, findings in mice with myeloid-cell-specific GLUT1 overexpression suggest that if increased glucose flux promotes atherosclerosis, myeloid cells are not sufficient for this effect.