转录因子NF-E2相关因子2对急性肺损伤小鼠的保护作用研究

Protective effects of transcription factor NF-E2-related factor 2 on acute lung injury in mice

目的探讨转录因子NF-E2相关因子2(Nrf2)对急性肺损伤(ALI)小鼠的保护作用及其机制。方法采用随机数字表法将小鼠分为对照组、ALI组、Nrf2干扰溶剂对照组(干扰溶剂组)和Nrf2干扰组4组,每组9只。Nrf2干扰组于尾静脉注射Nrf2小干扰RNA(si RNA),干扰溶剂组尾静脉注射等量干扰溶剂,对照组和ALI组于尾静脉注射等量0.9%氯化钠溶液,1次/d,连续3d。第4天时,ALI组、干扰溶剂组和Nrf2干扰组腹腔注射脂多糖(LPS)10mg/kg制备内毒素诱发ALI模型,对照组则腹腔内注射等量0.9%氯化钠溶液。注射LPS或0.9%氯化钠溶液6h后,麻醉开腹,从下腔静脉取静脉血,采用ELISA法检测血清IL-6、TNF-α水平。光镜下观察肺组织形态学变化,并进行肺损伤评分,测定并计算小鼠肺湿重/干重比值。采用Western blot法检测肺组织Nrf2核蛋白表达水平,采用比色法检测肺匀浆组织中髓过氧化物酶(MPO)、一氧化氮合酶(iNOS)水平。结果与对照组比较,ALI组、干扰溶剂组和Nrf2干扰组肺组织病理学损伤评分、湿重/干重比值、IL-6、TNF-α、MPO、iNOS水平升高,Nrf2核蛋白表达水平上调,差异均有统计学意义(均P<0.05)。与ALI组比较,Nrf2干扰组肺组织病理学损伤评分、湿重/干重比值、IL-6、TNF-α、MPO、iNOS水平升高,NRF2核蛋白表达水平下调,差异均有统计学意义(均P<0.05)。结论 Nrf2 siRNA可下调Nrf2核蛋白表达水平,从而加重LPS诱导的小鼠ALI的严重程度,使血清促炎症因子水平和肺组织中氧化应激损伤指标升高,提示Nrf2对ALI的保护作用与其抗炎和抗氧化作用有关。

Objective To investigate the effects of transcription factor NF-E2 related factor 2 （Nrf2） on acute lung injury （ALI） in mice. Methods Thirty six male mice were divided into 4 groups： normal control group （group C）, the acute lung injury group （ALI group）, the Nrf2 interference vehicle group （vehicle group） and the Nrf2 interference group. Nrf2 interference group was injected with siRNA against gene Nrf2 via tail vein once a day for three days, while vehicle group was injected with vehicle; and groups C and ALI group were injected with normal saline. On the 4th day acute lung injury was induced by intraperitoneal injection of LPS in the last three groups and normal saline was injected in the control group. The levels of IL-6 and TNF-α in serum were measured by ELISA method 6h after the injection of LPS or normal saline. The mice were then sacrificed, and the pathological changes in lung tissue were observed under light microscope to get the lung injury scores. The lung wet/dry weight（W/D） ratio of the mice in each group was calculated, and the expression of Nrf2 nucleoprotein in lung tissue was measured. The activity of MPO and iNOS was assayed. Results Compared with the group C, the lung injury score, the W/D ratio and the levels of IL-6, TNF-α, MPO, iNOS and Nrf2 protein were increased significantly in ALI group, vehicle group and Nrf2 interference groups（all P〈0.05）. Compared with the ALI group, the Nrf2 expression was reduced, while the lung injury score, the W/D ratio, the levels of IL-6, TNF-α, MPO and iNOS in Nrf2 interference group were increased （all P〈0.05）. Conclusion The study suggests that the Nrf2 transcription factor exerts its protection from the damage in mouse ALI model through a mechanism of reducing inflammation and oxidative stress.