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Protective effects of taurine on endothelial cells impaired by high glucose and oxidized low density lipoproteins

Ulrich-Merzenich, Gudrun, Zeitler, Heike, Vetter, Hans, Bhonde, Ramesh R.
European journal of nutrition 2007 v.46 no.8 pp. 431-438
adhesion, apoptosis, atherosclerosis, caspase-3, diabetes, endothelial cells, glucose, humans, hyperglycemia, low density lipoprotein, protective effect, taurine, umbilical cord
Background Endothelial dysfunction, common to diabetes and cardiovascular diseases, is an early step in the development of atherosclerosis and diabetic angiopathies. Deficiencies of taurine have been related to diabetes and cardiovascular diseases. Aims of the study We investigated whether taurine provides protective action against endothelial dysfunction induced by hyperglycemia and/or oxidized low density lipoproteins (oxLDL). Methods Quiescent human umbilical cord venous endothelial cells were exposed for 20 h to high glucose (35 mM) and/or oxLDL (60 μg/ml) alone and in presence of taurine (0.5-2.5 mg/ml). Apoptosis, caspase-3 activity, soluble(s) and cell surface expressions of vascular cellular (VCAM-1) and intercellular (ICAM-1) adhesion molecules were determined. Results are given as a percentage of the low glucose medium control. Apoptosis, VCAM-1 and ICAM-1 expressions were related to cell number. Results Hyperglycemia increased apoptosis to 162.5 ± 19.2%, caspase-3 activity to 153.2 ± 10.3%, cell-surface exp ression of VCAM-1 to 125.1 ± 5.8%, the expression of ICAM-1 to 123.7 ± 2.8% and sICAM-1 to 146.5 ± 7.9%. Taurine (0.5-2.5 mg/ml) restored apoptosis, caspase-3 activity and expressions of VCAM-1 and ICAM-1. OxLDL (60 μg/ml) increased apoptosis to 114.8 ± 3.1%; taurine (2.5 mg/ml) reduced this apoptosis to 40.5 ± 4.1%. The combination of hyperglycemia and oxLDL increased apoptosis to 211.7 ± 11.6%. This increase was normalized by taurine (2.5 mg/ml) to 97.9 ± 12.8%. Conclusion Taurine protects HUVECs from endothelial dysfunction induced by hyperglycemia through down-regulation of apoptosis and adhesion molecules. Counteracting the combination of oxLDL and hyperglycemia requires pharmacological concentrations of taurine.