Free radical producing activity and intracellular signal transduction mechanisms of phagocytes by heavy metals

为探讨氧化锌引起金属烟雾热的病因学机制，研究了氧化锌对腹膜洗脱的大鼠中性粒细胞和小鼠巨噬细胞样细胞RAW 264.7的激活机制。在中性粒细胞中加入氧化锌作为刺激剂，NADPH氧化酶可通过GTP结合蛋白、蛋白激酶C、酪氨酸激酶、胞内钙和膜CR3等细胞内信号转导途径产生超氧化物(O2~-)和过氧化氢(H_2O_2)。如果将GSH加入到氧化锌中，酸性氧物种的产生除了依赖于CR3外，还依赖于FcGammaR。比较了氧化锌和氧化锌加还原型谷胱甘肽对中性粒细胞的激活作用。氧化锌对中性粒细胞的激活可能依赖于NADPH氧化酶和一氧化氮合酶(NOS)产生O2~-和亚硝酸根(ONOO^-)。中性粒细胞的激活可能是通过激活主要定位于线粒体的单胺氧化酶(MAO)来实现的。这些结果表明，POT不仅为H_2O_2的起源与核转录因子的激活和细胞凋亡的病因提供了新的证据，而且也发现了MAO与细胞内信号转导机制的关系。此外，从Raw 246.7的结果来看，谷胱甘肽促进了氧化锌颗粒的吞噬清除，由此推测，锌烟热可能是由氧化锌颗粒以外的内在因素谷胱甘肽引起的。

The activation mechanisms of intraperitoneal-eluted rat neutrophils and mouse macrophage -like cell line Raw 264.7 by zinc oxide (ZnO) was investigated to explore the etiological mechanisms of metal fume fever induced by ZnO.The activation of phagocytes by ZnO was enhanced by the addition of glutathione (GSH) and thiol compounds. Superoxide (O2^-) and hydrogen peroxide (H2O2) may be produced by NADPH oxidase via the intracellular signal transduction pathway such as GTP-binding protein, protein kinase C, tyrosine kinase, and intracellar calcium and membraneous CR3 if ZnO was added as a stimulant to neutrophils. If GSH was added to ZnO, the production of acitive oxygen species was dependent on FcgammaR in addition to CR3. The differnce in the activation of neutrophils by ZnO and ZnO plus GSH was investigated. The activation of neutrophils by ZnO may be dependent on the production of O2^- and peoxynitrite (ONOO^-) via NADPH oxidase and nitric oxide synthase (NOS). The activation of neutrophils by ZnO plus GSH may participated in the elevated H2O2 via the activation of monoamine oxidase (MAO) mainly localized in mitochodrium. These results suggest pot only the new evidence of the origin of H2O2 associated with the activation of nuclear transcription factor and the etiology of apoptosis but also the discovery of the relationship between MAO and intracellar signal transduction mechanisms. Moreover, from the results of Raw 246.7, GSH promoted the cleaning of ZnO particles by phagocytosis.From this research project, it is speculated that zinc fume fever may be caused by the intrinsic factor GSH in addition to ZnO particles.