磷脂转运蛋白参与烟草提取物诱导的Ⅱ型肺泡上皮细胞凋亡

Role of phospholipid transfer protein in cigarette smoke-induced apoptosis of RLE-6TN cells

目的研究磷脂转运蛋白(PLTP)在烟草提取物对大鼠Ⅱ型肺泡上皮凋亡中的作用。方法体外培养大鼠肺泡上皮RLE-6TN细胞株24 h,分别加入0.5%,1.0%和2.0%烟草提取物共培养24 h或48 h;委托上海吉玛公司合成siRNA-PLTP,并将siRNA-PLTP转染入RLE-6TN中,下调PLTP的表达后,观察烟草烟雾对RLE-6TN细胞凋亡的影响。Hochest染色后观察细胞核的形态学改变;流式细胞术检测细胞凋亡率;蛋白质印迹法(Western blot)检测PLTP的表达量和半胱氨酸天冬氨酸蛋白酶-3的活性。结果经不同浓度的(0.5%,1.0%,2.0%)烟草提取物作用后,细胞早期凋亡率由(1.68±0.098)%增加至(18.663±0.964)%(P<0.001);Hoechst染色可见部分凋亡细胞,核发白、固缩、染色质边集等现象;PLTP的表达和caspase-3的活性增加;将PLTP敲降后,可部分逆转烟草提取物诱导的RLE-6TN细胞中caspase-3的活性的增加(P<0.05)。结论 PLTP参与烟草提取物诱导大鼠肺泡上皮细胞的凋亡。

Objective To investigate the role of phospholipid transfer protein （PLTP） in cigarette smoke extract （CSE）-induced apoptosis of rat alveolar type II cells （RLE-6TN） in vitro. Methods Rat alveolar epithelial cell line RLE-6TN were transfected with a small interfering RNA （siRNA） targeting PLTP prior to exposure to different concentrations of CSE for 24 or 48 h. The morphological changes of the apoptotic cells were observed by fluorescence microscopy with Hochest staining, and the cell apoptosis rate was measured with flow cytometry. The expression level of PLTP and caspase-3 activity in the cells were examined with Western blotting. Results Exposure to CSE significantly increased the cell apoptosis rate from （1.68±0.098）%to （18.663 ± 0.964）%（P〈0.001）. Hoechst staining revealed distinct apoptotic changes in CSE-treated cells, which showed increased PLTP expression and caspase-3 activity. PLTP knockdown with the specific siRNA partly suppressed the SCE-induced enhanc-ement of caspase-3 activity in the cells. Conclusion PLTP may play a role in CSE-induced apoptosis of rat alveolar cells in vitro.