不同浓度PM_(2.5)对小鼠肺泡Ⅱ型上皮细胞MLE-12的损伤作用及SP-B表达影响

Effects of different concentrations of PM_(2.5)on mouse alveolar type Ⅱ epithelial cells and expression of SP-B

目的探讨不同浓度细颗粒物(PM_(2.5))对小鼠肺泡Ⅱ型上皮细胞MLE-12的损伤作用及肺表面活性蛋白-B(SP-B)表达的影响。方法将肺泡Ⅱ型上皮细胞MLE-12分为实验组和对照组。实验组采用加入12.5、25、50、100、200μg/mL PM_(2.5)混悬液的DMEM完全培养基培养,对照组采用DMEM完全培养基培养。培养24 h或48 h后,采用光学显微镜观察细胞形态,透射电镜观察细胞超微结构,RTCA仪观察细胞增殖能力;Western blotting法检测细胞中SP-B蛋白;qRT-PCR法检测细胞中SP-B mRNA。结果随着PM_(2.5)浓度的升高,实验组细胞形态和超微结构受损程度逐渐加重,可见板层小体受损等细胞器损伤现象,对照组细胞形态和超微结构正常;与对照组相比,PM_(2.5)呈浓度依赖性抑制实验组细胞的增殖。与对照组相比,实验组细胞SP-B蛋白和mRNA表达呈浓度依赖性下调(P均<0.05)。结论PM_(2.5)可呈剂量依赖性损伤小鼠肺泡Ⅱ型上皮细胞MLE-12,并下调SP-B表达。

Objective To investigate the damage effects of different concentrations of fine particulate matter(PM_(2.5))on the alveolar type Ⅱ epithelial cells(MLE-12)and to further to explore the effects on the changes of lung SP-B expres⁃sion.Methods Alveolar type Ⅱ epithelial cells(MLE-12)were divided into the experimental group and control group.The cells in the experimental group were cultured in DMEM complete medium supplemented with 12.5,25,50,100,200μg/mL PM_(2.5)suspension,while the cells in the control group were cultured in DMEM complete medium.After 24 or 48 h of culture,the cell morphology was observed by light microscope.The cell ultrastructure was observed by transmis⁃sion electron microscope.The cell proliferation was detected by RTCA.SP-B protein expression was detected by Western blotting,and SP-B mRNA was detected by qRT-PCR.Results The morphology and ultrastructure of cells in the control group were normal,while the cell morphology and ultrastructure damage degree in cells of the experimental group gradually increased with the increase of PM_(2.5)concentrations,which showed the damage of lamellar bodies and other organelles.Compared with the control group,PM_(2.5)inhibited the proliferation of cells in the experimental group in a concentration-de⁃pendent manner.Compared with the control group,the protein and mRNA expression levels of SP-B in cells in the experi⁃mental group decreased in a concentration-dependent manner(both P<0.05).Conclusion PM_(2.5)can damage the mor⁃phology and ultrastructure of MLE-12 cells and down-regulate the SP-B expression in a dose-dependent manner.