支气管肺发育不良新生鼠模型肺泡上皮细胞标志物的表达变化及意义

目的 研究高氧致支气管肺发育不良(bronchopulmonary dysplasia,BPD)新生鼠模型中Ⅰ型肺泡上皮细胞(typeⅠalveolar epithelial cells,AECⅠ)和Ⅱ型肺泡上皮细胞(typeⅡalveolar epithelial cells,AECⅡ)特异性标志物表达变化及其意义.方法 80只新生Wistar大鼠,于生后12 h内随机分为模型组(吸入氧浓度为85%)和对照组(吸入空气),每组40只.于暴露第7、14、21天,分别进行肺组织HE染色观察病理学改变,免疫荧光双标染色观察AECⅠ标志物水通道蛋白5(aquaporin 5,AQP5)及AECⅡ标志物表面活性蛋白C(surfactant protein C,SP-C)表达及定位,Western blot方法检测AQP5和SP-C的蛋白表达水平,real-time PCR方法检测AQP5和SP-C的mRNA表达水平.结果 模型组大鼠肺组织表现出肺泡数目减少,体积增大,结构简单化,肺泡间隔增厚,次级分隔减少等肺泡化障碍表现.免疫荧光双标染色可见,模型组AQP5及SP-C表达明显增多,表达位置紊乱,且双染细胞/SP-C阳性细胞的比例明显增高(P<0.001).与对照组比较,模型组中AQP5及SP-C蛋白表达从高氧暴露7 d开始增加,增高的趋势持续至21 d.模型组中mRNA表达水平,AQP5从暴露7 d开始,SP-C从14 d开始较对照组明显升高(P<0.05),且两组间差异随高氧暴露时间延长更加明显(P<0.05).结论 暴露高氧中的新生鼠BPD模型肺组织中,AECⅠ标志物AQP5及AECⅡ标志物SP-C均表达上调,发生转分化的AECⅡ明显增多,表明在BPD肺损伤后的修复中存在AECⅡ过度转分化现象.

Study of the variation in expression and the significance of markers for alveolar epithelial cells in bron-chopulmonary dysplasia newborn rats

Objective To investigate the variation in expression and the significance of markers indi-cating typeⅠalveolar epithelial cells ( AECⅠ) and type Ⅱ alveolar epithelial cells ( AECⅡ) in hyperoxia induced bronchopulmonary dysplasia( BPD) model. Methods A total of 80 term normal Wistar rats were randomly devided into model group (85% oxygen) or control group (room air) within 12 h after birth,with 40 rats in each group. On day 7,day 14,day 21 after exposure,the pathological characteristics of lung tissues were observed using HE staining, the expression and location of AECⅠ marker aquaporin 5 ( AQP5 ) and AECⅡmarker surfactant protein-C ( SP-C) were examined using immunofluorescence double staining. West-ern blot analysis was employed to examine the expressions levels of AQP5 and SP-C proteins,while real-time PCR was used to evaluate the mRNA expression of AQP5 and SP-C. Results Alveolar developmental disor-der was observed in lung tissues of the model group,including fewer,larger,simplified alveoli,thicker alveo-lar walls,and fewer alveolar secondary septa. Immunofluorescence double staining showed increased and dis-organized AQP5 and SP-C expression, with significantly higher ratio of double-stained cells/SP-C positive cells in the model group ( P<0. 001 ) . Comparing to the control group, the expression of AQP5 and SP-C protein increased from 7 d after hyperoxia exposure,which continued to 21 d. The mRNA expression levels of these two markers both significantly increased in the model group compared with the control group, with AQP5 starting from 7 d while SP-C starting from 14 d after hyperoxia exposure (P<0. 05),and the differ-ence between two groups became more significant with the exposure time extending. Conclusion The expression of AECⅠ marker AQP5 and AECⅡ marker SP-C both increase in the lung tissues of hyperoxia induced BPD newborn rats,with more AECⅡ transdifferentiated into AECⅠ. These changes of the markers indicate that there is excessive transdifferentiation of AECⅡ in the recovery process after BPD lung injury.