Silica phagocytosis causes apoptosis and necrosis by different temporal and molecular pathways in alveolar macrophages
Silica phagocytosis causes apoptosis and necrosis by different temporal and molecular pathways in alveolar macrophages
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DOI：
10.1007/s10495-012-0798-y
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发表时间：
2013-03-01
期刊：
影响因子：
7.2
通讯作者：
Knecht, David A.
中科院分区：
文献类型：
--
作者：
Joshi, Gaurav N.;Knecht, David A.
长期吸入结晶二氧化硅是一种职业危害，由于二氧化硅颗粒对肺细胞的毒性而导致矽肺。肺泡巨噬细胞在清除这些颗粒方面起着重要作用，巨噬细胞暴露在二氧化硅颗粒中会导致细胞死亡，并诱导凋亡标志物的产生。利用MH-S肺泡巨噬细胞的时间推移成像，建立了介导细胞死亡的关键分子事件的时间序列。结果表明，80%的巨噬细胞因凋亡而死亡，20%的巨噬细胞因明确的死亡途径而死亡。最早可检测到的细胞事件是吞噬溶酶体渗漏，发生在两种死亡模式的颗粒摄取后30至120分钟之间。细胞凋亡后3~6h，线粒体跨膜电位显著升高，与caspase-3和caspase-9的激活及细胞泡化密切相关。磷脂酰丝氨酸外化和核固缩发生在细胞泡化开始后30分钟~2小时。坏死细胞线粒体膜去极化，但不超极化，未见半胱氨酸氨基转移酶激活。随着线粒体膜电位的降低，细胞肿胀，这是坏死和凋亡的区别。所有接受细胞凋亡的细胞都遵循相同的时间序列，但吞噬溶酶体渗漏和其他事件之间的时间间隔因细胞而异。这些结果表明，晶态二氧化硅暴露可以导致细胞凋亡或坏死，并且每种情况都以明确但时间可变的顺序发生。吞噬溶酶体渗漏和超极化之间的长时间间隔与吞噬溶酶体渗漏直接导致细胞死亡的简单情景不一致。这些结果突出了使用细胞对细胞时间推移分析来研究复杂的途径的重要性，例如二氧化硅诱导的细胞死亡。
Chronic inhalation of crystalline silica is an occupational hazard that results in silicosis due to the toxicity of silica particles to lung cells. Alveolar macrophages play an important role in clearance of these particles, and exposure of macrophages to silica particles causes cell death and induction of markers of apoptosis. Using time-lapse imaging of MH-S alveolar macrophages, a temporal sequence was established for key molecular events mediating cell death. The results demonstrate that 80 % of macrophages die by apoptosis and 20 % by necrosis by clearly distinguishable pathways. The earliest detectable cellular event is phago-lysosomal leakage, which occurs between 30 and 120 min after particle uptake in both modes of death. Between 3 and 6 h later, cells undergoing apoptosis showed a dramatic increase in mitochondrial transmembrane potential, closely correlated with activation of both caspase-3 and 9 and cell blebbing. Externalization of phosphatidyl serine and nuclear condensation occurred 30 min-2 h after the initiation of cell blebbing. Cells undergoing necrosis demonstrated mitochondrial membrane depolarization but not hyperpolarization and no caspase activation. Cell swelling followed the decrease in mitochondrial membrane potential, distinguishing necrosis from apoptosis. All cells undergoing apoptosis followed the same temporal sequence, but the time lag between phago-lysosomal leakage and the other events was highly variable from cell to cell. These results demonstrate that crystalline silica exposure can result in either apoptosis or necrosis and each occurs in a well-defined but temporally variable order. The long time gap between phago-lysosomal leakage and hyperpolarization is not consistent with a simple scenario of phago-lysosomal leakage leading directly to cell death. The results highlight the importance of using a cell by cell time-lapse analysis to investigate a complex pathway such as silica induced cell death.