High ambient glucose concentration, linked to vascular complications in diabetes in vivo, modulates mRNA expression of fibronectin, collagen, tissue-type plasminogen activator, and plasminogen activator inhibitor and induces delayed replication and excess cell death in cultured vascular endothelial cells. To determine the role of high ambient glucose (30 mmol/l) in apoptosis, paired cultures of individual isolates of human umbilical vein endothelial cells (HUVECs) were exposed to both high (30 mmol/l) and low (5 mmol/l) concentrations of glucose for short-term (24, 48, and 72 h) and long-term (13 +/- 1 days) experiments. Incubation of HUVECs with high glucose for > 48 h increased DNA fragmentation (13.7 +/- 6.5% of total DNA, mean +/- SD) versus cultures kept in 5 mmol/l glucose (10.9 +/- 5.6%, P < 0.005), as measured by [3H]thymidine assays. Data were confirmed by apoptosis-specific fluorescence-activated cell sorter analysis of confluent HUVEC cultures, which displayed after long-term exposure to 30 mmol/l glucose a 1.5-fold higher prevalence of apoptosis than control cultures exposed to 5 mmol/l glucose (P < 0.005). In contrast, no increase in DNA fragmentation in response to 30 mmol/l glucose was seen for standardized cell lines (K 562, P 815, YT) and fibroblasts. Expression of clusterin mRNA, originally reported to be a molecular marker of apoptosis, was only slightly affected by short-term (24-h) high-glucose exposure but was significantly reduced after long-term incubation in 30 mmol/l glucose (82.2 +/- 13.8% of control) versus 5 mmol/l glucose, which questions the role of clusterin gene expression as a marker of apoptosis.(ABSTRACT TRUNCATED AT 250 WORDS)

SummaryWe evaluated the influence of high ambient glucose on cellular expression of adhesion molecules, known to mediate endothelial interaction of leucocytes and monocytes. Paired cultures of individual isolates of human umbilical vein endothelial cells (HUVECs) were studied by fluorescence activated cell sorter analysis after exposure to 30 vs 5 mmol/1 glucose. Incubation of HUVECs for 24h in 30 mmol/1 glucose increased ICAM-1 (intercellular adhesion molecule-i; 116.4 _+ 16.9 % of control, p _< 0.05), but not PECAM (platelet endothelial cell adhesion molecule) expression, compared to cultures kept in 5 mmol/1 glucose. Long-term exposure (13 + 1 days) of HUVECs to 30 mmol/1 glucose increased expression of ICAM-1 to 122.5 ___ 32.2 % (p < 0.002) and reduced that of PECAM to 86.9 __+_ 21.3 % vs the respective control culture in 5 mmol/1 glucose (p < 0.02). Stimulation of confluent HUVECs, kept in 30 vs 5 mmol/1 glucose for 13 + 1 days, with 20 U/ ml interleukin-1 for 24 h (ICAM-1) and 4 h (endothelial leukocyte adhesion molecule 1) resulted in reduced ICAM-1 (84.8 _+ 27.0 %,p < 0.05) and endothelial leukocyte adhesion molecule-1 (87.6 + 22.4 %, p < 0.05) expression vs control cells, while that of PE-CAM (t: 24 h) and vascular cell adhesion molecule-1 (t: 16 h) remained unchanged. In conclusion, it appears that differences in expression of adhesion molecules on HUVECs in response to high glucose reflects endothelial glucose toxicity, which may also induce endothelial dysfunction in diabetes. [Diabetologia (1995[Diabetologia ( ) 38: 1367[Diabetologia ( -1370 Key words High glucose, adhesion molecules, endothelial cells, interleukin-1, diabetes mellitus.Both insulin-dependent and non-insulin-dependent diabetes mellitus are associated with an increased risk for atherosclerosis. Endothelial dysfunction, which precedes the development of atherosclerotic lesions in diabetic patients, includes accelerated dis- appearance of capillary endothelium, weakening of intercellular junctions, altered protein synthesis and the appearance of specific adhesive glycoproteins on endothelial cells [1], promoting local attachment of monocytes and leukocytes as well as their transendothelial migration. The mechanisms leading to elevated plasma levels of shed soluble adhesion molecules in diabetes are unknown and may include their increased synthesis due to disease-specific factors, decreased clearance or just reflect the presence of inflammatory processes. As blood glucose levels, glycated haemoglobin and late diabetes-associated vascular complications are closely correlated [2], this study was designed to evaluate the effect of high ambient glucose concentrations on basal and interleukin-1 (IL-1) stimulated expression of the endothelial adhesion molecules, intercellular adhesion molecule-1 (ICAM-1), endothelial leukocyte adhesion molecule

SummaryWe evaluated the influence of high ambient glucose on cellular expression of adhesion molecules, known to mediate endothelial interaction of leucocytes and monocytes. Paired cultures of individual isolates of human umbilical vein endothelial cells (HUVECs) were studied by fluorescence activated cell sorter analysis after exposure to 30 vs 5 mmol/1 glucose. Incubation of HUVECs for 24h in 30 mmol/1 glucose increased ICAM-1 (intercellular adhesion molecule-i; 116.4 _+ 16.9 % of control, p _< 0.05), but not PECAM (platelet endothelial cell adhesion molecule) expression, compared to cultures kept in 5 mmol/1 glucose. Long-term exposure (13 + 1 days) of HUVECs to 30 mmol/1 glucose increased expression of ICAM-1 to 122.5 ___ 32.2 % (p < 0.002) and reduced that of PECAM to 86.9 __+_ 21.3 % vs the respective control culture in 5 mmol/1 glucose (p < 0.02). Stimulation of confluent HUVECs, kept in 30 vs 5 mmol/1 glucose for 13 + 1 days, with 20 U/ ml interleukin-1 for 24 h (ICAM-1) and 4 h (endothelial leukocyte adhesion molecule 1) resulted in reduced ICAM-1 (84.8 _+ 27.0 %,p < 0.05) and endothelial leukocyte adhesion molecule-1 (87.6 + 22.4 %, p < 0.05) expression vs control cells, while that of PE-CAM (t: 24 h) and vascular cell adhesion molecule-1 (t: 16 h) remained unchanged. In conclusion, it appears that differences in expression of adhesion molecules on HUVECs in response to high glucose reflects endothelial glucose toxicity, which may also induce endothelial dysfunction in diabetes. [Diabetologia (1995[Diabetologia ( ) 38: 1367[Diabetologia ( -1370 Key words High glucose, adhesion molecules, endothelial cells, interleukin-1, diabetes mellitus.Both insulin-dependent and non-insulin-dependent diabetes mellitus are associated with an increased risk for atherosclerosis. Endothelial dysfunction, which precedes the development of atherosclerotic lesions in diabetic patients, includes accelerated dis- appearance of capillary endothelium, weakening of intercellular junctions, altered protein synthesis and the appearance of specific adhesive glycoproteins on endothelial cells [1], promoting local attachment of monocytes and leukocytes as well as their transendothelial migration. The mechanisms leading to elevated plasma levels of shed soluble adhesion molecules in diabetes are unknown and may include their increased synthesis due to disease-specific factors, decreased clearance or just reflect the presence of inflammatory processes. As blood glucose levels, glycated haemoglobin and late diabetes-associated vascular complications are closely correlated [2], this study was designed to evaluate the effect of high ambient glucose concentrations on basal and interleukin-1 (IL-1) stimulated expression of the endothelial adhesion molecules, intercellular adhesion molecule-1 (ICAM-1), endothelial leukocyte adhesion molecule