Wallach-Dayan Shulamit B, Izbicki Gabriel, Cohen Pazit Y, Gerstl-Golan Regina, Fine Alan, Breuer Raphael
Lung Cellular and Molecular Laboratory, Inst. of Pulmonology, Hadassah Univ. Hospital, POB 12000, Jerusalem, Israel.
Am J Physiol Lung Cell Mol Physiol. 2006 Apr;290(4):L790-L796. doi: 10.1152/ajplung.00300.2004. Epub 2005 Nov 23.
Epithelial cells are considered to be a main target of bleomycin-induced lung injury, which leads to fibrosis in vivo. We studied the characteristics of in vitro bleomycin-induced apoptosis in a mouse lung epithelial (MLE) cell line. Bleomycin caused an increase of reactive oxygen species (ROS) resulting in oxidative stress, mitochondrial leakage, and apoptosis. These were associated with elevated caspase-8 and resultant caspase-9 activity and with upregulation of Fas expression. Glutathione and inhibitors of caspase-8 or caspase-9, but not of FasL, inhibited these effects, suggesting their dependence on ROS, caspase-8 and -9, in a Fas/FasL-independent pathway. However, postbleomycin-exposed MLE cells were more sensitive to Fas-mediated apoptosis. These results demonstrate that the initial bleomycin-induced oxidative stress causes a direct apoptotic effect in lung epithelial cells involving a regulatory role of caspase-8 on caspase-9. Fas represents an amplification mechanism, and not a direct trigger of bleomycin-induced epithelial cell apoptosis.
上皮细胞被认为是博来霉素诱导的肺损伤的主要靶点，这种损伤在体内会导致纤维化。我们研究了博来霉素在体外诱导小鼠肺上皮（MLE）细胞系凋亡的特征。博来霉素导致活性氧（ROS）增加，从而引起氧化应激、线粒体渗漏和凋亡。这些与半胱天冬酶-8升高以及由此产生的半胱天冬酶-9活性增加以及Fas表达上调有关。谷胱甘肽以及半胱天冬酶-8或半胱天冬酶-9的抑制剂，但不是FasL的抑制剂，可抑制这些效应，表明它们在Fas/FasL非依赖途径中依赖于ROS、半胱天冬酶-8和-9。然而，博来霉素处理后的MLE细胞对Fas介导的凋亡更敏感。这些结果表明，最初博来霉素诱导的氧化应激在肺上皮细胞中引起直接凋亡效应，涉及半胱天冬酶-8对半胱天冬酶-9的调节作用。Fas代表一种放大机制，而不是博来霉素诱导上皮细胞凋亡的直接触发因素。
