类表皮生长因子域7在高体积分数氧致新生大鼠新型支气管肺发育不良中的表达及其意义

目的 观察类表皮生长因子域7(EGFL7)在高体积分数氧(高氧)致新生大鼠新型支气管肺发育不良(BPD)中的表达,探讨EGFL7在新型BPD发生发展中的可能作用.方法 足月新生 SD大鼠64只在出生12 h内,根据吸入氧浓度的不同随机分为实验组和对照组.实验组持续暴露于600 mL·L-1氧气中,对照组吸入空气.分别取2组大鼠生后4 d、7 d、10 d和14 d肺组织标本,HE染色观察其肺组织病理改变,免疫组织化学方法检测其血小板内皮细胞表面黏附分子-1(PECAM-1)的表达,以PECAM-1阳性染色的内皮细胞面积与肺实质细胞总面积的百分比代表肺微血管密度,采用实时荧光定量-PCR技术和Western blot法分别检测其EGFL7 mRNA和蛋白表达.结果 1.实验组600 mL·L-1氧气暴露14 d后,大鼠肺组织结构发生类似新型 BPD 的病理改变.2.PECAM-1蛋白主要表达于肺微血管内皮细胞的胞质中,实验组 PECAM-1蛋白和肺微血管密度均下降,与对照组比较差异均有统计学意义(P<0.05,0.01).3.实验组新生大鼠肺组织EGFL7 mRNA和蛋白表达在出生4 d、7 d、10 d、14 d均低于对照组(Pa<0.05,0.01).4.实验组EGFL7蛋白水平与肺微血管密度呈正相关(r=0.432,P<0.01).结论 EGFL7参与了新型BPD发生发展的整个过程,可能与肺微血管发育障碍有关.

Expression of Epidermal Growth Factor-Like Domain 7 in Lung Tissue of Neonatal Rats with Hyperoxia-Induced New Bronchopulmonary Dysplasia and Its Significance

Objective To observe the expression of epidermal growth factor-like domain 7(EGFL7) in lung tissue of neonatal rats with hyperoxia-induced new bronchopulmonary dysplasia(BPD)and explore the possible effect of EGFL7 on development of new BPD.MethodsSixty-four full-term newborn Sprague-Dawley rats were randomly divided into experimental group and control group according to the density of inhaled oxygen.The rats of experimental group began to breathe 600 mL·L-1 oxygen after 12 hours of postnatal age while rats in control group were exposed to room air.They were sacrificed for lung tissue on the 4,7,10,and 14 day,respectively.The pathological change was observed by using hematoxylin-eosin stain and the platelet endothelial cell adhesion molecule-1(PECAM-1) protein was detected by immunohistochemistry(IHC)method.Capillary density was quantified by measuring the area of PECAM-1 immunostaining in proportion to the total area of parenchymal cells.The mRNA and protein expressions of EGFL7 were determined by using real time fluorescent quantitative PCR and Western blot.Results1.Fourteen days after being exposed to 600 mL·L-1oxygen,similar pathological changes occurred in the structure of lungs of the rats,compared with that of the new BPD.2.PECAM-1 protein was expressed predominantly in cytoplasm of pulmonary microvascular endothelial cells.Both PECAM-1 and capillary density in experimental group were decreased compared with control group(P<0.05,0.01).3.The mRNA and protein expressions of EGFL7 after birth on 4,7,10,and 14 day were significantly decreased in experimental group compared with control group(Pa<0.05,0.01).4.The protein level of EGFL7 in experimental group was positively correlated with capillary density(r=0.432,P<0.01).ConclusionEGFL7 is involved in the whole process of new BPD and may be linked to pulmonary microvascular dysplasia.J Appl Clin Pediatr,2011,26(6): 408-411