Omi/HtrA2在高体积分数氧早产大鼠肺损伤中的作用

Role of Omi/HtrA2 in Hyperoxia-Induced Lung Injury of Premature Rats

目的研究Omi/HtrA2在早产大鼠高体积分数氧(高氧)肺损伤中的作用。方法早产Wistar大鼠48只随机分为高氧组和对照组。高氧组大鼠暴露于950 mL.L-1氧气中,对照组置于空气中。在处理后1 d、3 d、7 d每组分批处死8只大鼠后收集肺组织。采用HE染色观察其肺组织病理变化;免疫组织化学链霉菌抗生物素蛋白-过氧化物酶连结法(SP)法检测Omi/HtrA2、X连锁凋亡抑制蛋白(XIAP)和半胱氨酰天冬氨酸特异性蛋白酶-9(Caspase-9)在各组早产大鼠肺组织的表达和分布;采用原位末端转移酶标记技术(TUNEL)评价其肺组织细胞凋亡情况;采用间接免疫荧光双染色法,在激光共聚焦显微镜下观察Omi/HtrA2在细胞内的转位。结果 1.高氧组早产大鼠可见典型的肺损伤病理学改变。2.Omi/HtrA2、XIAP和Caspase-9主要表达于肺组织细胞的胞质。对照组中Omi/HtrA2有少量表达。高氧损伤后Omi/HtrA2的表达呈时间依赖性,于1 d时表达开始增加,3 d时明显增加,7 d时表达最多;高氧1 d时XIAP表达有所减少,3 d时明显减少,7 d最少;高氧1 d时Caspase-9表达开始增加,3 d时明显增加,7 d时表达最多。3.高氧组3 d时出现明显的肺细胞凋亡,7 d凋亡细胞数达高峰。4.与对照组比较,高氧组肺泡上皮细胞内Omi/HtrA2转位率明显增加。结论 Omi/HtrA2可能通过抑制XIAP、激活Caspase-9促进早产大鼠高氧后肺组织细胞的凋亡。

Objective To explore the role of Omi/HtrA2 in hyperoxia - induced lung injury of premature rats. Methods Forty - eight premature Wistar rats were randomly divided into control group and hyperoxia group. Rats in the hyperoxia group were exposed to 950 mL ~ L-1 oxygen, while rats in the control group were exposed to air. The lung tissues in 2 groups were obtained on the first day, the 3rd day and the 7th day after exposed to either room air or hyperoxia. Section of lungs were stained with hematoxylin eosin to observe the histologic changes. Streptavidin - peroxidase immunohistochemistry was used to detect the expressions of Omi/HtrA2, X-linked inhibitor of apoptosis protein （XLAP） and Caspase- 9 in the lung cell of each group. Terminal deoxynucleotidyL transferase -mediated dUTP- biotin nick end labeling assay was used to detect the apoptosis of lung cell. The translocation of Omi/HtrA2 was determined by indirect immunofluoreseence and ob- served under eorffoca2 microscopy. Results 1. The typical pathologic characters of lung injury were discovered in hyperoxia group. 2. Oral/ HtrA2, XIAP and Caspase - 9 expressed generally in the cytoplasm of lung tissue. The expression of Omi/HtrA2 was few in the control group. Compared with the control group,Omi/HtrA2 in hyperoxia group began to increase on the first day and significantly increased on the 3nd day and peaked on the 7th day. XIAP began to decrease from the first day and significantly decreased on the 3rd day. The expression level of XIAP was least on the 7th day. Caspase - 9 began to increase in hyperoxia group from the first day and significantly increased on the 3nd day and peaked on the 7th day. 3. A few of TUNEL- positive cells began to increase from the first day in hyperoxia group,significantly increase on the 3nd day and peaked on the 7th day. 4. Using immunofluorescence, Omi/HtrA2 could be significantly translocated to cytosol. Conclusion Omi/ HtrA2 can promote hyperxia -induced lung cell apoptosis in premature rats through inhibiting XIAP and activating Caspase -9.