脓毒症小鼠急性肺损伤时血红素氧合酶-1表达与自噬的关系

Relationship between heme oxygenase-1 expression and autophagy during acute lung injury in septicmice

目的评价脓毒症小鼠急性肺损伤时血红素氧合酶-1（HO-1）表达与自噬的关系。 方法雄性C57BL/6小鼠48只，6～8周龄，体重20～25 g，采用随机数字表法分为4组（n＝12）：假手术组（SH组）、脓毒症组（CLP组）、HO-1激动剂Hemin＋脓毒症组（Hemin＋CLP组）和HO-1抑制剂SnPP＋脓毒症组（SnPP＋CLP组）。CLP组、Hemin＋CLP组和SnPP＋CLP组采用盲肠结扎穿孔法制备脓毒症模型。Hemin＋CLP组及SnPP＋CLP组于术前2 h分别腹腔注射Hemin 50 μmol/kg和SnPP 50 μmol/kg。术后24 h时颈动脉取血样，行血气分析，记录PaO2，计算氧合指数；取肺组织，光镜下行肺损伤评分，透射电镜下计数自噬小体，测定湿重/干重比值（W/D比值），采用Western blot法测定HO-1、Beclin-1和微管相关蛋白1轻链3Ⅱ型（LC3Ⅱ）的表达水平。 结果与SH组比较，CLP组、Hemin＋CLP组及SnPP＋CLP组氧合指数降低，肺组织W/D比值、自噬小体计数和肺损伤评分升高，CLP组和Hemin＋CLP组肺组织HO-1、Beclin-1和LC3Ⅱ的表达上调（P〈0.05）。与CLP组比较，Hemin＋CLP组氧合指数和肺组织自噬小体计数升高，W/D比值和肺损伤评分降低，肺组织HO-1、Beclin-1和LC3Ⅱ的表达上调，SnPP＋CLP组氧合指数和肺组织自噬小体计数降低，W/D比值和肺损伤评分升高，HO-1、Beclin-1和LC3Ⅱ的表达下调（P〈0.05）。 结论HO-1表达上调介导自噬，参与了脓毒症小鼠急性肺损伤内源性保护机制。

Objective To evaluate the relationship between heme oxygenase-I （HO-1） expression and autophagy during acute lung injury in septic mice. Methods Forty-eight male C57BL/6 mice, aged 6-8 weeks, weighing 20-25 g, were randomly divided into 4 groups （n= 12 each） using a random number table： sham operation group （group SH） , sepsis group （group CLP） , HO-1 agonist hemin plus sepsis group （group Hemin＋CLP） and HO-1 inhibitor SnPP plus sepsis group （group SnPP＋CLP）. Sepsis was induced by cecal ligation and puncture in CLP, Hemin＋CLP and SnPP＋CLP groups. Hemin 50 μmol/kg and SnPP 50 μmol/kg were intraperitoneally injected at 2 h before operation in Heroin＋ CLP group and SnPP＋CLP group, respectively. Arterial blood samples were taken at 24 h after operation for blood gas a- nalysis, PaO2 was recorded, and oxygenation index was calculated. Lungs were removed for examination of pathological changes which were scored and for determination of autophagosome count （with an electron mi- croscope） , weight/dry weight ratio （W/D ratio） and expression of HO-1, Becling-1 and microtubule-asso-ciated protein 1 light chain 3 11 （LC3 ]I ） in lung tissues （by Western blot）. Results Compared with group SH, oxygenation index was significantly decreased, and W/D ratio, autophagosome count and patho- logical scores were increased in C LP, Hemin＋CLP and SnPP＋CLP groups, and the expression of HO-1, Beclin-1 and LC3 Ⅱ was significantly up-regulated in CLP and Hemin＋CLP groups （P〈0. 05）. Compared with group CLP, oxygenation index and autophagosome count were significantly increased, W/D ratio and pathological scores were decreased, and the expression of HO-1, Beelin-1 and LC3 Ⅱwas up-regulated in group Hemin＋CLP, and oxygenation index and autophagosome count were significantly decreased, W/D ra- tio and pathological scores were increased, and the expression of HO-1, Beclin-1 and LC3 II was down- regulated in group SnPP＋CLP （P〈O. 05）. Conclusion Up-regulated expression of HO-1 mediates autoph- agy, which is involved in the endogenous protective mechanism underlvinz acute lunz iniurv in sentic mice.