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


OBJECTIVE
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 microg/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 expression 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 microg/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%.


CONCLUSIONS
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.
Ulrich-Merzenich
Gudrun
G
Medical Policlinic of the Friedrich-Wilhelm-University of Bonn, Wilhelmstrasse 35-37, 53111 Bonn, Germany. gudrun.ulrich-merzenich@ukb.uni-bonn.de
Zeitler
Heike
H
Vetter
Hans
H
Bhonde
Ramesh R
RR
D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects*; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000737:chemistry / Q000494:pharmacology*; D010084:Oxidation-Reduction; D013654:Taurine / Q000172:deficiency* / Q000494:pharmacology*; D014471:Umbilical Veins / Q000166:cytology; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism
D008077:Lipoproteins, LDL; D019010:Vascular Cell Adhesion Molecule-1; C099252:oxidized low density lipoprotein; D018799:Intercellular Adhesion Molecule-1; D013654:Taurine; D053148:Caspase 3; D005947:Glucose