膜联蛋白A1基因敲除加重大鼠体外循环后肺损伤

Annexin A1 gene knockout aggravates lung injury after cardiopulmonary bypass in rats

目的研究膜联蛋白A1(AnxA1)基因敲除后对大鼠体外循环(CPB)肺损伤的影响。方法分别将12只12~16周龄,体重350~450g,全身AnxA1基因敲除(AnxA1-/-)大鼠(KO大鼠)和野生型SD大鼠(WT大鼠)分为假手术组(Sham组)和CPB肺损伤模型组(IR组)。Sham组仅行血管穿刺置管,IR组构建CPB模型,分别在体外循环前(T 1)、开放肺门后(T 2)和实验结束时(T 3)取动脉血行血气分析,计算大鼠氧合指数(OI)和呼吸指数(RI),术中记录大鼠生命体征。实验结束后处死大鼠取左肺组织,用苏木精-伊红(H&E)染色观察肺组织形态学改变;电子显微镜下观察肺泡II型上皮细胞的状态;TUNEL法检测肺组织中性粒细胞的凋亡率;Western blot法检测AnxA1的表达。结果WT-IR组AnxA1表达较WT-Sham组明显增加(P<0.05),KO组未检测到内源性AnxA1的表达;肺功能指标:T 3时刻KO-IR组OI明显低于WT-IR组(P<0.05),KO-IR组RI显著高于WT-IR组(P<0.05);KO-IR组肺组织损伤评分高于WT-IR组(P<0.05);电子显微镜下观察到KO-IR组肺泡II型上皮细胞出现坏死,而WT-IR组未见坏死;KO-IR组中性粒细胞凋亡率较WT-IR组明显降低(P<0.05)。结论AnxA1基因敲除大鼠CPB后肺损伤程度较野生型大鼠明显加重,提示内源性AnxA1对减轻CPB肺损伤具有一定积极的作用。

Objective To study the effect of Annexin A1(AnxA1)gene knockout(AnxA1-/-)on lung injury induced by cardiopulmonary bypass(CPB)in rats.Methods The subjects of this research were 12 AnxA1-/-rats(KO rats)and 12 Sprague Dawley wild-type rats(WT rats),aged 12-16 weeks and weighed 350-450g.Both kinds of rats were divided into control group(Sham group)and CPB lung injury model group(IR group).Rats in the Sham group were only catheterized.And the CPB model was established in the IR group rats.Arterial blood was taken for blood gas analysis at three time points:before extracorporeal circulation(T1),after opening the hilum(T2)and at the end of the experiment(T3).The oxygenation index(OI)and respiratory index(RI)were calculated.Vital signs of rats were recorded during the experiment.Lung tissue was stained with hematoxylin-eosin(HE)to observe the morphological changes.The state of alveolar type II epithelial cells was observed under an electron microscope.Deoxynucleotidyl transferase-mediated d UTP notch labeling(TUNEL)staining was used to detect the apoptosis rate of neutrophils in lung tissue.Western blot was used to detect the expression of AnxA1 in lung tissue.Results The level of AnxA1 in the WT-IR group was significantly higher than that in the WT-Sham group(P<0.05).There was no endogenous AnxA1 was detected in the KO group.At the time of T 3,the OI of the KO-IR group was significantly lower than that of the WT-IR group(P<0.05),and the RI of the KO-IR group was significantly higher than that of the WT-IR group(P<0.05).The score of lung injury in KO-IR group was higher than that in WT-IR group(P<0.05).Under electron microscope,necrosis of alveolar type II epithelial cells was observed in KO-IR group,but not viewed in WT-IR group.The neutrophil apoptosis rate in lung tissue of KO-IR group was significantly lower than that of WT-IR group(P<0.05).Conclusion After CPB,lung injury of AnxA1 gene knockout rats was more serious than that of wild-type rats.Endogenous AnxA1 had a positive effect on reducing CPB lung injury.