Effect of tea polyphenols on oxidative damage and apoptosis in human bronchial epithelial cells induced by low-dose cigarette smoke condensate

Abstract

To determine the effect of tea polyphenols on oxidative damage and apoptosis in human bronchial epithelial cells induced by low-dose cigarette smoke condensate (CSC). We prepared CSC. 3-(4,5-dimethyl thiazoly) 2,5-diphenyl-tetrazoliun bromide (MTT) assay was used to determine the growth of cultured human bronchial epithelial cells (HBE135-E6E7). Fluorescent-chemiluminescent analyzer was used to measure cell reactive oxygen species (ROS) level. DNA ladder method was used to detect HBE135-E6E7 apoptosis. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect Bcl-2 and Bax mRNA expression. Concentration of intracellular ROS in the CSC group and CSC + TP group was significantly higher than that in the control group (P<0.01); concentration of intracellular ROS in the CSC + TP group was significantly lower than that in the CSC group (P<0.01). Apparent DNA breakage of the tail belt appeared in the CSC Group,while only a small amount of DNA breakage of the tail belt appeared in the CSC + TP group. Compared with the control group, Bcl-2 mRNA expression was reduced and Bax mRNA expression was increased in the CSC group (all P<0.01). Compared with the CSC group, Bcl-2 mRNA expression was increased and Bax mRNA expression was reduced in the CSC+TP group (all P<0.01). Ratio of Bcl-2 mRNA/ Bax mRNA in the CSC group and CSC+TP group was significantly lower than that in the control group (all P<0.01). TP can antagonize CSC-induced airway epithelial cell apoptosis through the effective removal of ROS, promoting Bcl-2 mRNA expression and inhibiting the expression of Bax mRNA.