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目的探讨NF-κB在幼兔较大潮气量机械通气致肺生物伤中的作用以及对肿瘤坏死因子α(TNF-α)和白细胞介素8(IL-8)的影响。方法27只普通级幼兔随机等分为3组,(1)对照组(NMV,n=9):不进行机械通气;(2)常规机械通气组CMV(CMV,n=9):潮气量(VT)=8ml/kg;(3)大潮气量机械通气组(LMV,n=9):VT=24ml/kg。采用凝胶电泳迁移率改变分析法(EMSA)检测各时相点肺组织核蛋白提取物中NF-κB活性,WesternBlot法测定肺组织IκBα含量,同时应用RT-PCR和ELISA法检测肺组织匀浆中TNF-α和IL-8mRNA表达及其蛋白含量,并观察肺组织病理改变。结果在各时相点LMV的NF-κB活性明显高于NMV和CMV(P<0·01);CMV的NF-κB活性则高于NMV(P<0·01)。IκBα含量在LMV随通气时间延长呈进行性降低,与NMV和CMV比较有显著性差异(P<0·01)。机械通气后LMV的TNF-α和IL-8含量及表达较CMV、NMV明显增高(P<0·01),TNF-α表达及含量在通气后4h达高峰,6h明显降低,而继TNF-α达峰后,IL-8在通气后6h达最高。肺组织病理学显示,随通气时间延长,LMV的肺泡结构破坏,肺泡壁和肺间质内有大量中性粒细胞浸润和较多红细胞渗出。CMV的肺间质及肺泡壁轻度水肿、有少量粒细胞浸润。NMV未见病理性改变。结论在损害性机械通气肺损伤的发生过程中,IκBα降解和NF-kB活化可能参与了肺组织致炎细胞因子基因表达的调控过程。
Objective To investigate the role of NF-κB in the pathogenesis of lung biopsy caused by mechanical ventilation in rabbits with high tidal volume as well as its effects on tumor necrosis factor-α (TNF-α) and interleukin-8 (IL-8) Methods 27 normal rabbits were randomly divided into three groups: (1) control group (NMV, n = 9): no mechanical ventilation; (2) CMV (VT) = 8ml / kg; (3) Large tidal volume mechanical ventilation group (LMV, n = 9): VT = 24ml / kg. The activity of NF-κB in lung tissue nuclear extracts was detected by EMSA at different time points. The content of IκBα in lung tissues was determined by Western Blot. The lung homogenates were detected by RT-PCR and ELISA TNF-αand IL-8mRNA expression and protein content, and observe the pathological changes of lung tissue. Results The NF-κB activity of LMV was significantly higher than that of NMV and CMV at each time point (P <0.01). The NF-κB activity of CMV was higher than that of NMV (P <0.01). The level of IκBα decreased progressively with the prolongation of ventilation time, which was significantly different from that of NMV and CMV (P <0.01). After mechanical ventilation, the levels and expressions of TNF-α and IL-8 in LMV were significantly higher than those in CMV and NMV (P <0.01). The expression and content of TNF-α peaked at 4h and decreased significantly at 6h after ventilation, After reaching the peak, IL-8 reached the highest at 6h after ventilation. Lung histopathology showed that the alveolar structure of LMV was destroyed with the prolongation of ventilation time, there was a large number of neutrophil infiltration and more erythrocyte exudation in the alveolar wall and interstitium. CMV pulmonary interstitial and alveolar wall mild edema, a small amount of granulocyte infiltration. NMV no pathological changes. Conclusion Degradation of IκBα and activation of NF-κB may be involved in the regulation of proinflammatory cytokine gene expression in lung tissue during the development of damaging lung injury induced by mechanical ventilation.