呼吸机所致肺损伤肿瘤坏死因子-α的表达及核因子-κB活性的实验研究

Tumor Necrosis Factor-α Expression and Nuclear Factor-kappa B Activation in Ventilator-Induced Lung Injury in Rabbits

目的研究呼吸机所致肺损伤(VILI)时肿瘤坏死因子-α(TNF-α)的表达及核因子-κB(NF-κB)DNA结合活性的变化,探讨VILI炎症反应的分子生物学机制。方法应用大潮气量(VT)机械通气建立兔VILI模型。40只雄性新西兰兔随机分为对照组、常规VT组、损伤1 h组2、h组及4 h组。用酶联免疫吸附法(ELISA)检测肺组织匀浆TNF-α含量,反转录多聚酶链反应(RT-PCR)检测mRNA表达。凝胶电泳迁移率分析法(EMSA)测定NF-κB的活性。同时检测动脉血氧分压(PaO2)和肺湿质量/干质量比值(W/D)及肺组织病理学检查。结果1)损伤4 h组PaO2较常规VT组显著降低(P<0.05),损伤4 h组W/D较对照组和常规VT组显著升高(P均<0.01)。2)损伤2 h组和损伤4 h组肺组织匀浆中TNF-α含量均显著高于对照组和常规VT组(P均<0.01)。各损伤组TNF-αmRNA含量均显著高于对照组和常规VT组(P均<0.01),损伤4 h组高于损伤1 h组(P<0.01)和损伤2 h组(P<0.05)。3)各损伤组NF-κB的DNA结合活性均显著高于对照组和常规VT组(P均<0.01),2 h活性达峰值,4 h仍维持在高水平。结论TNF-α升高参与了VILI的炎症反应过程,其升高可能与其mRNA表达增高有关。NF-κB的DNA结合活性增高可能参与了VILI时TNF-α的基因转录过程。

Objective The expression of tumor necrosis factor-α（TNF-α） and the activation of nuclear factor- kappa B（NF-kB） were examined in order to investigate the molecular mechanism of ventilator-induced lung injury （VILI）. Methods The VILI model was established by mechanical ventilation with a VT of 40 mL/kg. Forty healthy male New Zealand rabbits were randomly divided into control group, conventional ventilation group and VILI group. The concentrations of TNF-α in lung homogenate were measured by enzyme-linked immunosorbent assay （ELISA）. The TNF-α mRNA was measured by semi quantitative transcription-polymerase chain reaction （RT PCR）. The DNA binding activity of NF-kB was detected by electrophoretic mobility shift assay （EMSA）. The partial arterial blood pressure of oxygen （PaO2）, wet lung weight to dry lung weight ratio （W/D） and histological changes of lung tissue were also investigated. Results 1） After 4 h of injurious ventilation, PaO2 was significantly reduced compared with conventional ventilation group （P〈 0.05）. In contrast, the W/D was significantly increased increased with control group （P〈 0.01 ） and conventional ventilation group （P〈 0.01）. 2） The concentrations of TNF-α proteins in lung homogenates were significantly increased by the injurious ventilation for 2 h or 4 h, compare to control group and conventional ventilation group （all P〈0. 01）. The TNF-α mRNA levels in all injurious ventilation groups were significantly higher than control group （all P 〈 0.01 ） and conventional ventilation group （ P 〈 0.01 ）. The TNF-α mRNA levels induced by injurious ventilation for 4 h were significantly higher than that induced by injurious ventilation for 1 h （P〈 0.01） and 2 h （P 〈 0.05）. 3） The DNA-binding activity of oxymatrine was significantly increased in all injurious ventilation groups compared with that of control and conventional ventilation group （ P〈 0.01）. The DNA-binding activity of NF-kB reached to maximal level at 2 h and remained until 4 h. Conclusion The mRNA and protein level of TNF-α and DNA binding activity of NF-kB were up-regulated by VILI. Increased NF-kB activity in the lung may be involved in the transcriptional up-regulation of TNF-α.