Quinlan T R, BeruBe K A, Hacker M P, Taatjes D J, Timblin C R, Goldberg J, Kimberley P, O'Shaughnessy P, Hemenway D, Torino J, Jimenez L A, Mossman B T
Department of Pathology, University of Vermont, Burlington 05405, USA.
Free Radic Biol Med. 1998 Mar 15;24(5):778-88. doi: 10.1016/s0891-5849(97)00357-2.
To evaluate the contribution of reactive nitrogen species to inflammation by asbestos, Fischer 344 rats were exposed to crocidolite or chrysotile asbestos by inhalation to determine whether increases occurred in nitric oxide (NO.) metabolites from alveolar macrophages (AMs). AMs from animals inhaling asbestos showed significant elevations (p < .05) in nitrite/nitrate levels which were ameliorated by NG-monomethyl-L-arginine (NMMA), an inhibitor of inducible nitric oxide synthase (iNOS) activity. Temporal patterns of NO. generation from AMs correlated with neutrophil influx in bronchoalveolar lavage samples after asbestos inhalation or bleomycin instillation, another model of pulmonary fibrosis. To determine the molecular mechanisms and specificity of iNOS promoter activation by asbestos, RAW 264.7 cells, a murine macrophage-like line, and AMs isolated from control rats were exposed to crocidolite asbestos in vitro. These cells showed increases in steady-state levels of iNOS mRNA in response to asbestos and more dramatic increases in both iNOS mRNA and immunoreactive protein after addition of lipopolysaccharide (LPS). After transfection of an iNOS promoter/luciferase reporter construct, RAW 264.7 cells exposed to LPS, crocidolite asbestos and its nonfibrous analog, riebeckite, revealed increases in luciferase activity whereas cristobalite silica had no effects. Studies suggest that NO. generation may be important in cell injury and inflammation by asbestos.
为评估活性氮物质在石棉所致炎症中的作用，将Fischer 344大鼠通过吸入暴露于青石棉或温石棉，以确定肺泡巨噬细胞（AM）产生的一氧化氮（NO.）代谢产物是否增加。吸入石棉的动物的AM中亚硝酸盐/硝酸盐水平显著升高（p <.05），而可诱导型一氧化氮合酶（iNOS）活性抑制剂NG-单甲基-L-精氨酸（NMMA）可改善这种升高。吸入石棉或博来霉素（另一种肺纤维化模型）后，支气管肺泡灌洗样本中AM产生NO.的时间模式与中性粒细胞流入相关。为确定石棉激活iNOS启动子的分子机制和特异性，将RAW 264.7细胞（一种小鼠巨噬细胞样细胞系）和从对照大鼠分离的AM在体外暴露于青石棉。这些细胞在接触石棉后iNOS mRNA的稳态水平增加，在添加脂多糖（LPS）后iNOS mRNA和免疫反应性蛋白均有更显著的增加。转染iNOS启动子/荧光素酶报告构建体后，暴露于LPS、青石棉及其非纤维类似物钠闪石的RAW 264.7细胞显示荧光素酶活性增加，而方石英二氧化硅则无影响。研究表明，NO.的产生可能在石棉所致的细胞损伤和炎症中起重要作用。
