Endocytosis of ultrafine particles by A549 cells
Endocytosis of ultrafine particles by A549 cells
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DOI：
10.1165/ajrcmb.24.2.4081
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发表时间：
2001-02-01
影响因子：
6.4
通讯作者：
Godleski, JJ
中科院分区：
文献类型：
--
作者：
Stearns, RC;Paulauskis, JD;Godleski, JJ
肺泡上皮细胞摄取吸入超细颗粒的能力还没有很好的表征。本研究的目的是使用II型肺上皮细胞的体外模型，并评价细胞摄取超细颗粒（二氧化钛[TiO 2]，直径50 nm）的能力。人上皮细胞系A549生长在aclar基板上，并暴露于40 μ g/ml的TiO 2颗粒3，6，和24小时，然后用能量过滤透射电子显微镜成像。元素分布和电子能量损失谱被用来共定位Ti/O与电子致密颗粒。在用和不用细胞松弛素D（cyto a）（2 μ g/ml）预处理的A549细胞中比较颗粒内吞作用。TiO 2暴露3小时后，细胞内化聚集的超细颗粒，观察到在细胞溶质，膜结合的空泡。暴露24小时后，有相当多的细胞内聚集的膜结合颗粒，和聚集的颗粒也陷入松散和紧密包装的板层体。在整个24小时的曝光的颗粒的优势仍然与细胞的自由表面，并没有内化。尽管使用了几种不同的方法来确保单个颗粒被摄入和检测的可能性，但大多数膜结合空泡含有颗粒聚集体，仅偶尔含有两个或三个颗粒。有微丝紊乱的形态学证据，但没有证据表明细胞D预处理的细胞中内化颗粒减少。因此，该II型上皮模型能够内化超细颗粒的聚集体。
Alveolar epithelium's capacity to ingest inhaled ultrafine particles is not well characterized. The objectives of this study were to use an in vitro model of type II lung epithelium and evaluate the cells' ability to take up ultrafine particles (titanium dioxide [TiO2], 50 nm diameter). The human epithelial cell line A549 was grown on aclar substrates and exposed to 40 mug/ml TiO2 particles for 3, 6, and 24 h before imaging with energy-filtering transmission electron microscopy. Elemental mapping and electron energy loss spectroscopy were used to colocalize Ti/O with electron-dense particles. Particle endocytosis was compared in A549 cells with and without pretreatment with cytochalasin D (cyto a) (2 mug/ml). After 3 h of TiO2 exposure, cells internalized aggregates of the ultrafine particles which were observed in cytosolic, membrane-bound vacuoles. After 24 h of exposure there were considerably more intracellular aggregates of membrane-bound particles, and aggregated particles were also enmeshed in loosely and tightly packed lamellar bodies. Throughout 24 h of exposure a preponderance of particles remained associated with the free surface of the cells and were not internalized. The majority of membrane-bound vacuoles contained aggregates of particles and only occasionally did they contain as few as two or three particles, despite the use of several different approaches to assure the possibility for individual particles to be ingested and detected. There was morphologic evidence of microfilament disturbance, but no evidence of a decrease in internalized particles in cells pretreated with cyto D. Thus, this model of type II epithelium is able to internalize aggregates of ultrafine particles.