血红素氧合酶-1对老年大鼠呼吸机相关肺损伤的保护作用

Protective effect of heme oxygenase-1 against ventilator-induced lung injury in elderly rats

目的 探讨血红素氧合酶-1(HO-1)对老年大鼠呼吸机相关肺损伤(VILI)的保护作用。方法 48只老年大鼠随机分为常规通气对照组(C组)、呼吸机相关肺损伤组(VILI组)、氯铁血红素干预组(Hemin组)、铬卟啉干预组(CrMP+Hemin组)。C组采用小潮气量通气4 h;VILI组采用致伤性大潮气量通气4 h;Hemin组和CrMP+Hemin组均给予HO-1特异性诱导剂(氯铁血红素),其中CrMP+Hemin组加用抑制剂(铬卟啉),通气条件同VILI组。机械通气4 h后处死大鼠,分光光度计和Western印迹分别检测各组肺组织HO-1活性与蛋白表达,HE染色观察肺组织病理改变并计算肺损伤评分,考马斯亮蓝法测定支气管肺泡灌洗液(BALF)中蛋白含量,计算肺湿干比,化学比色法检测肺组织丙二醛(MDA)含量、总抗氧化能力(TAC)变化。结果 在机械通气4 h后,与C组比较,VILI组肺组织HO-1蛋白水平和活性、肺损伤评分、BALF蛋白含量、肺湿干比及MDA含量明显升高(P<0.05),TAC明显下降(P<0.05)。Hemin组较VILI组的HO-1蛋白水平和活性、TAC明显升高(P<0.05),肺损伤评分、BALF蛋白含量、肺湿干比及MDA含量明显下降(P<0.05)。与Hemin组比较,CrMP+Hemin组HO-1蛋白表达和活性、TAC明显降低(P<0.05),肺损伤评分、BALF蛋白含量、肺湿干比及MDA含量明显升高(P<0.05)。结论 氯铁血红素通过诱导HO-1表达减轻老年大鼠VILI肺损伤,改善肺内氧化应激,对老年大鼠VILI具有保护作用,可能成为VILI防治的有效靶点。

Objective To investigate the effect of heme oxygenase-1(HO-1)on ventilator-induced lung injury(VILI in elderly rats. Methods Elderly rats were divided into the control group(C),VILI group,hemin pretreatment group(Hemin)and chromium mesoporphyrin pretreatment+hemin pretreatment group(CrMP+Hemin). C group received four hours of mechanical ventilation at a low tidal volume. Rats in VILI group were subjected to 4-hour mechanical ventilation at a high tidal volume. Rats in Hemin group received pretreatment with hemin(a specific HO-1 inducer). Rats in CrMP+Hemin group received pretreatment with hemin and CrMP(a specific HO-1 inhibitor). After the pretreatment,rats in both the Hemin group and the CrMP+Hemin group were subjected to mechanical ventilation with the same setting as VILI group. After four hours of mechanical ventilation,these rats were sacrificed and lung samples were collected. HO-1enzymatic activities and protein levels were measured by spectrophotometry and Western blotting analysis. The lung histopathology and lung injury score were assessed with hematoxylin and eosin staining. The bronchoalveolar lavage protein content was estimated by the Bradford assay and the lung wet/dry ratio was calculated. Lung malondialdehyde(MDA)content and total antioxidative capacity(TAC)were detected by chemical colorimetry to evaluate lung oxidative stress status. Results After four hours of mechanical ventilation,rats in VILI group exhibited elevated HO-1 protein levels and activities,as well as profound lung injury and oxidative status compared with rats in C group. Compared to VILI group,hemin pretreatment was associated with enhanced induction of HO-1 expressions and activities,improved lung injury indexes as well as less oxidative stress. Conversely,coadministration with CrMP and hemin in GrMP+Hemin group prevented this hemin-induced upregulation of HO-1 expressions and activities,and abolished the attenuation of lung injury and oxidative stress in old rats. Conclusion Hemin play a protective role against VILI in elderly rats by suppressing oxidative stress through HO-1 upregulation. HO-1 may be a promising intervention target for VILI prevention and treatment.