Inflammation Determines the Pro-Adhesive Properties of High Extracellular D-Glucose in Human Endothelial Cells In Vitro and Rat Microvessels In Vivo

Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain.
PLoS ONE (Impact Factor: 3.23). 04/2010; 5(4):e10091. DOI: 10.1371/journal.pone.0010091
Source: PubMed


Hyperglycemia is acknowledged as an independent risk factor for developing diabetes-associated atherosclerosis. At present, most therapeutic approaches are targeted at a tight glycemic control in diabetic patients, although this fails to prevent macrovascular complications of the disease. Indeed, it remains highly controversial whether or not the mere elevation of extracellular D-glucose can directly promote vascular inflammation, which favors early pro-atherosclerotic events.
In the present work, increasing extracellular D-glucose from 5.5 to 22 mmol/L was neither sufficient to induce intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression, analyzed by flow cytometry, nor to promote leukocyte adhesion to human umbilical vein endothelial cells (HUVEC) in vitro, measured by flow chamber assays. Interestingly, the elevation of D-glucose levels potentiated ICAM-1 and VCAM-1 expression and leukocyte adhesion induced by a pro-inflammatory stimulus, such as interleukin (IL)-1beta (5 ng/mL). In HUVEC, high D-glucose augmented the activation of extracellular signal-regulated kinase 1/2 (ERK 1/2) and nuclear transcription factor-kappaB (NF-kappaB) elicited by IL-1beta, measured by Western blot and electromobility shift assay (EMSA), respectively, but had no effect by itself. Both ERK 1/2 and NF-kappaB were necessary for VCAM-1 expression, but not for ICAM-1 expression. In vivo, leukocyte trafficking was evaluated in the rat mesenteric microcirculation by intravital microscopy. In accordance with the in vitro data, the acute intraperitoneal injection of D-glucose increased leukocyte rolling flux, adhesion and migration, but only when IL-1beta was co-administered.
These results indicate that the elevation of extracellular D-glucose levels is not sufficient to promote vascular inflammation, and they highlight the pivotal role of a pro-inflammatory environment in diabetes, as a critical factor conditioning the early pro-atherosclerotic actions of hyperglycemia.

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    • "Human umbilical vein endothelial cells (HUVEC) were enzymatically isolated, as previously described [20]. For experiments, cells at passages 1-4 were incubated with different compounds in M199 medium supplemented with 10% FCS, ECGS and antibiotics for 18 h. "
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    • "Accordingly, transmigration of neutrophils as observed in giemsa-stained cremaster muscle whole mounts of ICAM1-KO and in LFA1-KO mice was similar after administration of glucose compared to normal saline (Figures 1(b), 1(f), and 1(g)). These findings suggest that ICAM1 and LFA1 are crucially involved in mediating glucose-induced leukocyte recruitment, which is in line with previous observations [8, 33]. "
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    • "Human umbilical vein endothelial cells (HUVEC) were enzymatically isolated with collagenase and cultured in M199 medium supplemented with 10% FCS, 25 mg/mL ECGS, 100 mg/mL heparin and antibiotics, as previously described [16]. For experiments, HUVEC at passages 1–5 were used. "
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