姜黄素活化Nrf2-ARE通路对百草枯诱导Ⅱ型肺泡细胞氧化损伤的保护作用

Curcumin reduces paraquat-induced oxidative injury in A549 cells by activation of the Nrf2-ARE pathway

目的研究姜黄素（curcumin）对百草枯（paraquat，PQ）诱导的Ⅱ型肺泡细胞氧化损伤的保护作用及机制。方法常规培养A549细胞，分空白对照组、姜黄素对照组、PQ组及姜黄素＋PQ组，处理24h，MTr法检测细胞存活率、RT-PCR及Western blot法检测A549细胞NFE2L2表达、ELISA法检测细胞内HO-1、NQO-1及上清液超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活力及丙二醛（MDA）水平。并以siRNA技术低表达Nrf2，观察其对姜黄素拈抗PQ诱导A549细胞氧化损伤指标的影响。结果0．1mmol／LPQ即能明显抑制A549细胞生长，并呈剂量依赖性；而160μmol／L以下姜黄素对A549细胞生长无明显抑制作用。800μmol／LPQ组A549细胞SOD活力明显降低，CAT活力及MDA水平均明显升高，与空白对照组比较，差异有统计学意义（P（o．05，P〈0．01）。80μmol／L姜黄素＋PQ组，SOD及CAT活力较PO组明显升高，MDA水平明显降低，差异有统计学意义（P〈0．01）。与对照组比较，PQ染毒组NFE2L2及其下游因子HO-1、NQO-1表达均明显升高，差异有统计学意义（P〈0．01）；姜黄素＋PQ组NFE2L2及HO-1、NQO-1表达水平较PQ组升高，差异均有统计学意义（P〈0．01）。与姜黄素＋PQ组比较，姜黄素＋PQ＋NFE2L2siRNA组SOD、CAT活力均明显下降，MDA水平明显升高，差异有统计学意义（P〈O．01）。结论小剂量姜黄素在体外能明显拮抗PQ诱导的A549细胞氧化损伤，这种保护作用依赖于Nrf2-ARE通路的活化。

Objective To investigate the protective effect of curcumin （CU） on type II alveolar epithelial cells （A549 cells） during paraquat （PQ）-induced oxidative damage and its underlying mechanism. Methods Routinely cultured A549 cells were divided into blank control group, CU control group, PQ group, and PQ＋Cu group to receive respective treatments for 24 h. Cell viability was determined by MTF assay. The NFE2L2 expression in A549 cells was measured by RT-PCR and Western blot. The activities of the heine oxygenase-1 （HO-1） and NAD（P）H： quinone oxidoreduetase 1 （NQO-1） in cells and the superoxide dismntase （SOD） and catalase （CAT） in supernatant, as well as malondialdehyde （MDA） content, were measured by enzyme-linked immunosorbent assay. After siRNA depletion of Nrf2, the protective effect of CU on A549 cells during PQ- induced oxidative damage was evaluated. Results PQ, even at a dose of 0.1 mmol/L, could significantly suppress the viability of A549 cells in a dose-dependent manner. CU showed no significant inhibitory effect on the viability of A549 cells when given at a dose below 160 μmol/L. Compared with the blank control group, the PQ group had significantly decreased SOD activity and significantly increased CAT activity and MDA content after 24-h exposure to 800 μmol/L PQ （P〈0.05 or P〈0.01）. Thanks to pretreatment with 80 μmol/L CU, the PQ＋CU group had significantly increased SOD and CAT activities and significantly decreased MDA content compared with the PQ group （P〈0.01）. Compared with the blank control group, the PQ group had significantly increased expression of NFE2L2 and its downstream factors HO-1 and NQO-1 （P〈0.01）, while the PQ＋CU group had significantly higher expression of NFE2L2, HO-1, and NQO-1 than the PQ group （P〈0.01）. Compared with the PQ＋ CU group, the CU＋PQ＋NFE2L2siRNA group had significantly decreased SOD and CAT activities and significantly increased MDA content （P〈0.01）. Conclusion Low-dose CU significantly reduces the PQ-induced oxidative damage in A549 cells in vitro by activation of the Nrf2-ARE pathway.