INHIBITION OF OXIDIZED LIPOPROTEINS INDUCED APOPTOSIS OF HUMAN UMBILICAL VEIN ENDOTHELIAL CELLS BY TEA POLYPHENOLS

Objective: To study the inhibition and mechanism of tea polyphenols (TP) on apoptosis induced by oxidized low density lipoprotein (ox-LDL) in human umbilical vein endothelial cells (HUVEC). Method: HUVEC cells were administered with TP (25 μg/ml), ox-LDL (200 μg/ml)+TP (25 μg/ml), ox-LDL (200 μg/ml) respectively, cells with equal volume of solvent as control. Cell viability was determined by MTT assay, apoptosis by acridine orange fluorescence dyeing, and expressions of Bcl-2、Bax and caspase-3 were analyzed by Western blotting. Results: Ox-LDL could inhibit HUVEC cell proliferation. After treated with both TP and ox-LDL , the cell proliferation increased obviously and showed significant difference from the cells treated with ox-LDL only (P0.05) Ox-LDL also induced HUVEC apoptosis, and TP decreased this effect. The results of Western blotting showed that ox-LDL markly downregulated Bcl-2 protein expression and upregulated Bax and caspase-3 protein expressions of HUVEC, while TP+ox-LDL treatment showed that Bcl-2 protein expression increased and Bax and caspase-3 protein expressions decreased significantly. Conclusion: TP could inhibit apoptosis induced by ox-LDL through its modulating effect on the expressions of Bcl-2, Bax and caspase-3 proteins.