Effect of epigallocatechin-3-gallate on cell proliferation and apoptosis of mouse podocytes exposed to high glucose

Objective To investigate the influence of epigallocatechin-3-gallate(EGCG)on apoptosis and cell proliferation of mouse podocytes exposed to high glucose.Methods Mouse podocytes were randomly divided into 9 groups:normal glucose group(5.6 mmol/L,group 1),normal glucose(5.6 mmol/L)+0.1 mmol/LH2O2(group 2),DMEM high glucose(25 mmol/L,group 3),20 μmol/L EGCG+ DMEM high glucose(25 mmol/L,group 4),2.0 μmol/L EGCG+DMEM high glucose(25 mmol/L,group 5),0.2 μmol/L EGCG+ DMEM high glucose(25 mmol/L,group 6),0.2 mmol/L vitamin E+DMEM high glucose(25 mmol/L),0.1 μmol/L EGCG+0.1 mmol/L vitamin E+DMEM high glucose(25 mmol/L,group 8),and 24.4 mmol/L mannitol+5.6 mmol/L glucose(group 9).Cell proliferation was examined by BrdU ELISA assay.The influences of different concentrations of EGCG(24 h treatment)on cell apoptosis were observed by Hoechst 33258 staining and confocal laser scanning microscopy.The apoptosis of cells was examined by annexin fluorescein isothiocyanate(V-FITC)binding by flow cytometry.The intracellular ROS production was measured by fluorescent probe CM-H2DCFDA by fluorescence microscopy.Results ① Compared with group 1,the proliferation of podocyte(D450 value)in group 2 was comparable 24 h after stimulation,and was significantly lower 48 and 72 h after stimulation(P0.05).Compared with group 2,the D450 values in group 7,8 were significantly higher(P0.05)and in group 4,5,and 6 had no significant changes;those in group 4,7,and 8 were significantly increased after 48 and 72 h(P0.01).② Cell apoptosis in group 2 and 3 was more severe than that in group 1;that in group 7 was slighter than that in group 4 and 5;and that in group 9 was similar to that in group 2.③ EGCG decreased the early apoptosis of cells exposed to high glucose in a time-and dose-dependent manner.EGCG(2.0 Um,20 μmol/L),α-Tocopherol(0.2 μmol/L)with EGCG(0.1 μmol/L)and α-Tocopherol(0.2 μmol/L)decreased the percentage of apoptosis after 24 hr of incubation in high glucose(P0.05).Compared with α-Tocopherol(0.2 μmol/L)or EGCG(20 μmol/L),α-Tocopherol(0.2 μmol/L)combined with EGCG(0.1 μmol/L)significantly decreased the percentage of apoptosis after 24 h exposure to high glucose(P0.05).④ Compared with group 2,group 4 had significantly lower ROS production after 24 h(P0.05),group 6 had a similar ROS production to group 2.Compared with group 7,group 4 had significantly decreased ROS production at 24 h(P0.05),but had no significant changes after 6,and 12 h.Conclusion EGCG(20 μmol/L)can stimulate podocyte proliferation after 72 h incubation under high glucose condition.EGCG can also inhibit high glucose-induced podocyte apoptosis through suppressing the production of ROS.