表没食子儿茶素没食子酸酯对X线照射大鼠肺损伤及TNFα、TGFβ表达和SOD活性的影响

Effect of epigallocatechin gallate on TNFα and TGFβ expression,SOD activity and lung injury in rat radiation model

目的观察表没食子儿茶素没食子酸酯(EGCG)对放射线所致大鼠肺损伤的干预作用,并探讨其可能的作用机制。方法通过6MV X射线复制大鼠放射性肺损伤模型,随机分为模型对照组及大剂量[200mg/(kg.d)EGCG]、中剂量[100mg/(kg.d)EGCG]、小剂量[50mg/(kg.d)EGCG]干预组,采用H-E及VG染色观察肺组织病理变化和胶原沉积情况,并计算肺泡炎和肺纤维化积分,免疫组织化学(IHC)染色测定肿瘤坏死因子α(TNFα)、转化生长因子β(TGFβ)的表达水平,黄嘌呤氧化酶法测定超氧化物歧化酶(SOD)活性。结果 40d时模型对照组大鼠出现明显的肺泡炎和肺纤维化,中、大剂量EGCG干预组大鼠肺泡炎和纤维化积分均低于模型对照组(P<0.01);EGCG小剂量组肺泡炎及肺纤维化积分与模型对照组比较差异无统计学意义。10、20、40d时,EGCG中、大剂量组肺组织TNFα、TGFβ表达均低于模型对照组及EGCG小剂量组(P<0.01或P<0.05),而SOD活性均高于模型对照组及EGCG小剂量组(P<0.05)。结论中、大剂量EGCG能减轻放射线所致的肺泡炎和肺纤维化程度,其机制可能与抑制TNFα和TGFβ的表达、提高SOD活性有关。

Objective To evaluate the effect of epigallocatechin gallate on radiatiominduced lung injury in rats and to discuss the related mechanism. Methods Rat models of radiation-induced lung injury were produced by 6 MV X ray radiation, and then the animals were divided into model control group and low-, medium and high-dose （200, 100, 50 mg/[kg·d]） epigallocatechin gallate groups. The pulmonary histopathological changes and collagen disposition were observed by H-E staining and Van Gieson （VG） staining, and the scores of alveolitis and pulmonary fibrosis were calculated. The expression of tumor necrosis factor a （TNFa） and transforming growth factor 13 （TGF13） in lung tissues was examined by immunohistochemical （IHC） staining. The activity of superoxide dismutase （SOD） was examined by xanthine oxidase method. Results Apparent alveolitis and pulmonary fibrosis were observed in model rats at 40 d after radiation, and the scores of the alveolitis and pulmonary fibrosis were signficantly lower in medium- and high-dose epigallocatechin gallate groups than in the model control group （P（0.01）, and there was no difference between the low-dose epigallocatechin gallate group and the model control group. Pulmonary TNFa and TGFi3 expression was significantly lower in the medium- and high-dose epigallocatechin gallate groups than in the model control group and low dose epigallocatechin gallate groups at 10 d, 20 d, and 40 d after radiation （P〈0.01 or P〈0. 05） , while SOD activity in the former two groups were significantly higher compared with those in the model control group and low-dose epigallocatechin gallate groups （P〈0. 05）. Conclusion Medium- and high doseepigallocatechin gallate can ameliorate the alveolitis and pulmonary fibrosis in radiation-induced lung injury in rats, which might be associated with the inhibition of TNF-α, TGF-β expression and promotion of SOD activity.