Activated Neutrophils Induce Epithelial Cell Apoptosis Through Oxidant-Dependent Tyrosine Dephosphorylation of Caspase-8
Activated Neutrophils Induce Epithelial Cell Apoptosis Through Oxidant-Dependent Tyrosine Dephosphorylation of Caspase-8
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DOI：
10.1016/j.ajpath.2013.12.031
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发表时间：
2014-04-01
影响因子：
6
通讯作者：
Marshall, John C.
中科院分区：
文献类型：
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作者：
Jia, Song Hui;Parodo, Jean;Marshall, John C.
活化的中性粒细胞可通过氧化剂对膜磷脂的直接作用损伤宿主细胞，但诱导凋亡性细胞死亡的能力以前未见报道。我们发现，中性粒细胞在体内激活的患者谁持续多发性创伤或在体外暴露于细菌脂多糖促进上皮细胞凋亡，通过SHP-1介导的上皮细胞caspase-8的去磷酸化。持续严重损伤患者的循环中性粒细胞诱导的上皮细胞凋亡依赖于嗜中性粒细胞衍生的活性氧中间体的产生，并通过抑制NADPH氧化酶或恢复细胞内谷胱甘肽来阻断。Caspase-8在静息上皮细胞中组成性酪氨酸磷酸化，但在过氧化氢、活化中性粒细胞或抑制Src激酶时发生SHP-1依赖性去磷酸化。细胞转染突变型caspase-8，其中酪氨酸残基在Tyr 397或Tyr 465被替换为nonphosphorylatable苯丙氨酸进行加速凋亡，而无论是这些残基的突变磷酸模拟谷氨酸或转染Src激酶林恩或c-Src抑制过氧化氢诱导的细胞凋亡。暴露于过氧化氢或脂多糖刺激的中性粒细胞增加磷酸酶SHP-1的磷酸化和活性，增加半胱天冬酶8和3的活性，并加速上皮细胞凋亡。这些观察结果揭示了一种新的机制，通过氧化剂依赖性，SHP-1介导的caspase-8的去磷酸化，导致增强上皮细胞凋亡的嗜酸性粒细胞介导的组织损伤。
Activated neutrophils can injure host cells through direct effects of oxidants on membrane phospholipids, but an ability to induce apoptotic cell death has not previously been reported. We show that neutrophils activated in vivo in patients who have sustained multiple trauma or in vitro by exposure to bacterial lipopolysaccharide promote epithelial cell apoptosis through SHP-1-mediated dephosphorytation of epithelial cell caspase-8. Epithelial cell apoptosis induced by circulating neutrophils from patients who had sustained serious injury depended on the generation of neutrophil-derived reactive oxygen intermediates and was blocked by inhibition of NADPH oxidase or restoration of intracellular glutathione. Caspase-8 was constitutively tyrosine phosphorylated in a panel of resting epithelial cells, but underwent SHP-1-dependent dephosphorytation in response to hydrogen peroxide, activated neutrophils, or inhibition of Src kinases. Cells transfected with a mutant caspase-8 in which tyrosine residues at Tyr397 or Tyr465 are replaced by nonphosphorylatable phenylalanine underwent accelerated apoptosis, whereas either mutation of these residues to phosphomimetic glutamic acid or transfection with the Src kinases Lyn or c-Src inhibited hydrogen peroxide induced apoptosis. Exposure to either hydrogen peroxide or lipopolysaccharide-stimulated neutrophils increased phosphorylation and activity of the phosphatase SHP-1, increased activity of caspases 8 and 3, and accelerated epithelial cell apoptosis. These observations reveal a novel mechanism for neutrophil-mediated tissue injury through oxidant-dependent, SHP-1 mediated dephosphorylation of caspase-8 resulting in enhanced epithelial cell apoptosis.