Cheng N, Shi X, Ye J, Castranova V, Chen F, Leonard S S, Vallyathan V, Rojanasakul Y
Department of Basic Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia 26506, USA.
Exp Mol Pathol. 1999 Aug;66(3):201-10. doi: 10.1006/exmp.1999.2268.
Asbestos exposure in humans is associated with inflammatory, fibrotic, and malignant diseases in the lung. Increasing evidence supports the hypothesis that the production of proinflammatory cytokines such as tumor necrosis factor-alpha (TNFalpha) is an important mediator of the pathologic responses of asbestosis. In this study, we examine the role of nuclear transcription factor-kappaB (NF-kappaB) and free oxygen radicals in asbestos-induced TNFalpha gene and protein expression in lung macrophages. Exposure of the cells to crocidolite asbestos caused a parallel increase in TNFalpha production and NF-kappaB activation, as analyzed by enzyme-linked immunosorbent assay and electrophoretic mobility shift assay. Inhibition of NF-kappaB by SN50, an inhibitor of NF-kappaB nuclear translocation, or by sequence-specific oligonucleotides directed against the NF-kappaB binding site of TNFalpha promoter attenuated the asbestos effect on TNFalpha production. Gene transfection assays using an expression plasmid containing a luciferase reporter gene and a TNFalpha-derived NF-kappaB gene promoter further indicated the dependence of NF-kappaB activation on asbestos-induced gene expression. The effects of asbestos on NF-kappaB and TNFalpha activation were inhibited by oxygen radical scavengers and were enhanced by antioxidant enzyme inhibitors. These results indicate that asbestos-induced TNFalpha gene expression is mediated through a process that involves NF-kappaB activation and free radical reactions.
人体接触石棉与肺部的炎症、纤维化和恶性疾病有关。越来越多的证据支持这样一种假说，即肿瘤坏死因子-α（TNFα）等促炎细胞因子的产生是石棉沉着病病理反应的重要介质。在本研究中，我们研究了核转录因子-κB（NF-κB）和自由基在石棉诱导的肺巨噬细胞TNFα基因和蛋白表达中的作用。通过酶联免疫吸附测定和电泳迁移率变动分析发现，将细胞暴露于青石棉会导致TNFα产生和NF-κB激活同时增加。NF-κB核转运抑制剂SN50或针对TNFα启动子的NF-κB结合位点的序列特异性寡核苷酸对NF-κB的抑制减弱了石棉对TNFα产生的影响。使用含有荧光素酶报告基因和TNFα衍生的NF-κB基因启动子的表达质粒进行的基因转染试验进一步表明，NF-κB激活依赖于石棉诱导的基因表达。自由基清除剂抑制了石棉对NF-κB和TNFα激活的作用，而抗氧化酶抑制剂则增强了这种作用。这些结果表明，石棉诱导的TNFα基因表达是通过一个涉及NF-κB激活和自由基反应的过程介导的。
