Increase in GLUT1 in smooth muscle alters vascular contractility and increases inflammation in response to vascular injury.

ABSTRACT

OBJECTIVE: The goal of this study was to test the contributing role of increasing glucose uptake in vascular smooth muscle cells (VSMCs) in vascular complications and disease. METHODS AND RESULTS: A murine genetic model was established in which glucose trasporter 1 (GLUT1), the non-insulin-dependent glucose transporter protein, was overexpressed in smooth muscle using the sm22α promoter. Overexpression of GLUT1 in smooth muscle led to significant increases in glucose uptake (n=3, P<0.0001) as measured using radiolabeled 2-deoxyglucose. Fasting blood glucose, insulin, and nonesterified fatty acids were unchanged. Contractility in aortic ring segments was decreased in sm22α-GLUT1 mice (n=10, P<0.04). In response to vascular injury, sm22α-GLUT1 mice exhibited a proinflammatory phenotype, including a significant increase in the percentage of neutrophils in the lesion (n=4, P<0.04) and an increase in monocyte chemoattractant protein-1 (MCP-1) immunofluorescence. Circulating haptoglobin and glutathione/total glutathione were significantly higher in the sm22α-GLUT1 mice postinjury compared with controls (n=4, P<0.05), suggesting increased flux through the pentose phosphate pathway. sm22α-GLUT1 mice exhibited significant medial hypertrophy following injury that was associated with a significant increase in the percentage of VSMCs in the media staining positive for nuclear phosphoSMAD2/3 (n=4, P<0.003). CONCLUSIONS: In summary, these findings suggest that increased glucose uptake in VSMCs impairs vascular contractility and accelerates a proinflammatory, neutrophil-rich lesion in response to injury, as well as medial hypertrophy, which is associated with enhanced transforming growth factor-ß activity.