目的：研究茶多酚对低剂量烟草悬凝物诱导人支气管上皮细胞氧化损伤及凋亡的影响。方法：制备烟草悬凝物(cigarette smoke condensate, CSC)，采用四甲基偶氮唑盐［3-(4,5-dimethyl thiazoly)2,5-diphenyl-tetrazolium bromide，MTT］法测定人支气管上皮细胞株（HBE135-E6E7）的生长情况；荧光-化学发光仪测定细胞内氧自由基（reactive oxygen species，ROS）水平；DNA ladder 法检测HBE135-E6E7凋亡；反转录-多聚酶链式反应 (RT-PCR)法检测Bcl-2和Bax mRNA表达。结果：CSC组与CSC+茶多酚组细胞内ROS水平均明显高于对照组（P＜0.01），CSC+茶多酚组细胞内ROS水平则明显低于CSC组。CSC组出现明显的DNA断裂拖尾带，CSC+茶多酚组仅出现少量的断裂拖尾带。RT-PCR结果显示：与对照组相比, CSC组Bcl-2 mRNA表达降低 (P＜0.01), Bax mRNA表达升高 (P＜0.01);与CSC组相比, CSC+茶多酚组Bcl-2 mRNA表达升高 (P＜0.01), Bax mRNA表达降低 (P＜0.01),CSC组与CSC+茶多酚组 Bcl-2 mRNA/Bax mRNA值明显低于对照组(P＜0.01)。结论：茶多酚可拮抗CSC诱导人支气管上皮细胞凋亡，其机制可能是通过有效清除ROS，促进Bcl-2 mRNA表达和抑制Bax mRNA表达实现的。

ObjectiveTo determine the effect of tea polyphenols on oxidative damage and apoptosis in human bronchial epithelial cells induced by low-dose cigarette smoke condensate (CSC).MethodsWe 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.Results 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).ConclusionTP 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.

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