Mobilization of iron from urban particulates leads to generation of reactive oxygen species in vitro and induction of ferritin synthesis in human lung epithelial cells
Mobilization of iron from urban particulates leads to generation of reactive oxygen species in vitro and induction of ferritin synthesis in human lung epithelial cells
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DOI：
10.1021/tx960164m
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发表时间：
1997-07-01
影响因子：
4.1
通讯作者：
Aust, AE
中科院分区：
文献类型：
--
作者：
Smith, KR;Aust, AE
石棉在培养细胞中的许多生物化学作用已被证明是由于铁，其重量可高达27%。城市空气颗粒物也含有铁，吸入后的一些病理效应可能是由于铁催化反应产生的活性氧。两个标准参考物质（SRM）城市空气颗粒物样品用于这里描述的研究。SRM 1648（3.9重量%铁）收集于密苏里州圣路易斯地区，SRM 1649（3重量%铁）收集于华盛顿地区。为了确定与城市颗粒物相关的铁是否可以被动员，因为它来自石棉，将SRM 1648和1649与1 mM柠檬酸盐或EDTA在存在或不存在抗坏血酸盐的情况下孵育。铁从这两种颗粒通过任一螯合剂，特别是在抗坏血酸的存在下动员。在抗坏血酸存在下，柠檬酸盐在24小时内动员了30.9 nmol Fe/mg SRM 1648和65.1 nmol Fe/mg SRM 1649。在抗坏血酸存在下，EDTA在24小时内动员了53.8 nmol Fe/mg SRM 1648和98.8 nmol Fe/mg SRM 1649。为了确定颗粒铁是否产生活性氧物质，在存在或不存在抗坏血酸盐的情况下，将每个颗粒与phi X174 RFI DNA孵育。单链断裂（SSB）产生的颗粒，但只有在存在抗坏血酸。在抗坏血酸盐和柠檬酸盐存在下，SRM 1648或1649（0.5 mg/mL）与DNA一起孵育分别产生20%或34%的DNA与SSB。SRM 1648或1649（0.1 mg/mL）与DNA在抗坏血酸盐和EDTA存在下孵育分别产生26%或45%的DNA与SSB。为了确定与城市颗粒物相关的铁是否可以被人肺上皮细胞（A549）动员，用颗粒物处理细胞，并在处理结束时测定铁储存蛋白铁蛋白的量。在分别用SRM 1648或1649处理的细胞中观察到的铁蛋白比对照（未处理）细胞增加6.4或8.4倍，这强烈表明铁在培养的细胞中被动员。如果肺中也发生类似的铁动员和反应，这可能解释城市颗粒物的某些病理效应。
Many of the biochemical effects of asbestos in cultured cells have been shown to be due to iron, which can be as high as 27% by weight. Urban air particulates also contain iron, and some of the pathological effects after inhalation may be due to reactive oxygen species produced by iron-catalyzed reactions. Two standard reference material (SRM) urban air particulate samples were used for the studies described here. SRM 1648 (3.9% iron by weight) was collected in the St. Louis, MO, area, and SRM 1649 (3% iron by weight) was collected in the Washington, DC, area. To determine if iron associated with urban particulates could be mobilized, as it is from asbestos, SRMs 1648 and 1649 were incubated with 1 mM citrate or EDTA, in the presence or absence of ascorbate. Iron was mobilized from both particulates by either chelator, especially in the presence of ascorbate. Citrate, in the presence of ascorbate, mobilized 30.9 nmol of Fe/mg of SRM 1648 and 65.1 nmol of Fe/mg of SRM 1649 in 24 h. EDTA, in the presence of ascorbate, mobilized 53.8 nmol of Fe/mg of SRM 1648 and 98.8 nmol of Fe/mg of SRM 1649 in 24 h. To determine whether reactive oxygen species were being produced by the particulate iron, each particulate was incubated with phi X174 RFI DNA in the presence or absence of ascorbate. Single-strand breaks (SSBs) were produced by either particulate, but only in the presence of ascorbate. Incubation of SRM 1648 or 1649 (0.5 mg/mL) with DNA in the presence of ascorbate and citrate resulted in 20% or 34% DNA with SSBs, respectively. Incubation of SRM 1648 or 1649 (0.1 mg/mL) with DNA in the presence of ascorbate and EDTA resulted in 26% or 45% DNA with SSBs, respectively. To determine if iron associated with urban particulates could be mobilized by human lung epithelial cells (A549), cells were treated with particulates and the amount of the iron storage protein ferritin was determined at the end of treatment. The 6.4- or 8.4-fold increase in ferritin observed in cells treated with SRM 1648 or 1649, respectively, over that of control (untreated) cells strongly suggested that iron was mobilized in the cultured cells. If similar mobilization and reactivity of the iron occurs in the lung, this may explain some of the pathological effects of urban particulates.