羊膜腔内注射肺表面活性物质对宫内感染胎兔肺超微结构及表面活性蛋白A表达的影响

Intra-amniotic administration of pulmonary surfactant improves lung ultrastructural pathology and enhances surfactant protein A expression in fetal rabbits with intrauterine infection

目的观察羊膜腔内注射肺表面活性物质(PS)对胎膜早破宫内感染之胎兔肺组织超微结构及表面活性蛋白A(surfactant protein A,SP-A)表达的影响。方法建立胎膜早破宫内感染动物模型,在孕24,26d给予宫内注射大肠杆菌,分为细菌组和羊膜腔内注射PS组,干预后19.5h利用电镜观察肺超微结构变化,并分别用免疫组化法及Western blot(WB)法检测胎肺组织内SP-A表达,同时设立正常对照组。结果正常胎兔24、26d处于胎肺发育囊泡期,肺上皮细胞结构完整,可见典型Ⅰ型、Ⅱ型肺泡上皮细胞;细菌组和PS组胎兔肺泡内、支气管管腔内、胞质内均可见到杆菌菌体、浸润的炎症细胞;与对照组相比,细菌组Ⅱ型肺泡上皮细胞数量减少,板层体呈空泡化改变,有不同程度的凋亡;PS组Ⅱ型肺泡上皮细胞数量、板层小体数量较细菌组和对照组明显增多,且呈不同形式出现,细胞发生凋亡少。细菌组SP-A免疫组化及蛋白表达均降低,与对照组相比差异具有显著性(P<0.05);PS组SP-A表达升高,与对照组差异无显著性(P>0.05)。结论宫内感染后肺泡超微结构发生改变,SP-A表达下降;而在感染条件下羊膜腔内注射PS可改善肺泡超微结构的变化,并上调SP-A表达,对肺成熟有明显促进作用。

Objective To observe the effect of intra-amniotic administration of pulmonary surfactant （PS） on the lung ultrastructure and expression of surfactant protein A （SP-A） in fetal rabbit with intrauterine infection Methods Intra-amniotic PS injection was administered in a rabbit model of premature rupture of membrane and intrauterine infection induced by intrauterine colibacillus injection on the gestational days 24 and 26 days. The lung ultrastructural changes in the fetal rabbits were observed using electron microscope, and the expression of SP-A was measured with immunohistoehemical staining and Western blotting 19.5 h after the PS administration. Results alveolar type I cell （AT I）, alveolar type II cell （AT II）. In fetal rabbits with intrauterine colibacillus injection, inflammatory cell infiltration was observed in the pulmonary alveolus, bronchus lumens and intracytoplasm irrespective of PS administration. Compared with those in normal fetal rabbits, the number of alveolar type II cells （AT II） in the lung tissue decreased in fetal rabbits with intrauterine infection, and vacuolization of the lamellar bodies occurred with evidence of cell apoptosis; PS administration resulted in increased number of the AT II cells and lamellar bodies and reduced the cell apoptosis. The expression of SP-A was significantly lower in the infection group than in normal control group （P〈0.05）, but comparable between the PS group and the control group （P〉0.05）. Conclusion Changes in pulmonary alveolar ultrastructure and decreased expression of SP-A occur in fetal rabbits after intrauterine infection, and intra-amniotic administration of PS can alleviate these changes to promote lung maturation.