Production of nitric oxide elevates nitrosothiol formation resulting in decreased glutathione in macrophages exposed to asbestos or asbestos substitutes

Our plain-English summary of Production of nitric oxide elevates nitrosothiol formation resulting in decreased glutathione in macrophages exposed to asbestos or asbestos substitutes, by T. Nishiike, Y. Nishimura, Y. Wada, et al (Archives of Toxicology, 2005).

The study

• Authors: T. Nishiike, Y. Nishimura, Y. Wada, H. Iguchi
• Journal: Archives of Toxicology
• Published: 2005;79(2):83-9
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The purpose of this study was to investigate the effects of pneumoconiogenic particles, such as asbestos, on nitrosothiol formation in macrophages. In addition, the effects of man-made mineral fibers (MMMFs) were also evaluated, because they have come into heavy use as substitutes for asbestos. RAW264.7 cells and J774 cells of murine macrophage cell lines were cultured with chrysotile B (CH) asbestos, crocidolite (CR) asbestos, or MMMFs comprised of glass wool (GW), rock wool (RW), or ceramic (RF1). All of these fibers significantly increased nitric oxide (NO) production in the culture with macrophages. Chrysotile B, CR, and GW significantly decreased the level of reduced glutathione (GSH) in RAW264.7 cells. S-nitrosothiol (RS-NO) formation was increased by both types of cells on exposure to every fiber. A large portion of this increased RS-NO may be in the form of S-nitrosoglutathione (GS-NO), because GSH is the most abundant thiol substance in the cell. Both CH and GW significantly increased superoxide anion in the media cultured of RAW264.7 cells. These results indicate that macrophages exposed to asbestos or MMMFs are subject to oxidative stress, not only through the generation of reactive oxygen and nitrogen species, but also through decreases in the level of the cellular antioxidant, GSH, by GS-NO formation. The increase of RS-NO in macrophages exposed to asbestos or MMMFs may deserve more attention as the indicator of continuous oxidative stress by NO on cells and tissues, which causes inflammation and involves the development of asbestos-induced diseases.

In plain English

This was a laboratory (in vitro) experiment using two murine macrophage cell lines, RAW264.7 and J774, cultured with chrysotile B or crocidolite asbestos (UICC standard reference materials) or with man-made mineral fibers (glass wool, rock wool, ceramic fiber RF1), at 20 to 100 micrograms per well; nitrite (as an index of nitric oxide), glutathione and S-nitrosothiols (RS-NO) were measured after 24 or 48 hours, while superoxide anion was measured 3 hours after fibers were added, a time point chosen from a separate time-course experiment. In RAW264.7 cells, nitrite rose significantly with all five fibers at 100 micrograms (control 6.2 plus or minus 0.57 micromolar; crocidolite 11.5 plus or minus 1.14); in J774 cells it rose with chrysotile, glass wool and ceramic fiber, but not with crocidolite or rock wool. In RAW264.7 cells, reduced glutathione fell significantly with chrysotile, crocidolite and glass wool, and rose with RF1. RS-NO increased in both cell lines with every fiber at 100 micrograms. Superoxide in RAW264.7 cultures increased significantly only with chrysotile or rock wool. The authors concluded that asbestos and the substitutes caused oxidative stress including RS-NO formation.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: In vitro experiment using cultured murine macrophage cell lines exposed to mineral fibers
• Who was studied: Two murine macrophage cell lines, RAW264.7 and J774, seeded at 1 million cells per well of 12-well plates; experiments done at Hyogo College of Medicine, Japan (article received 2004)
• Exposure: Chrysotile B and crocidolite asbestos (UICC standard reference materials) and man-made mineral fibers (glass wool, rock wool, ceramic fiber RF1), at 20 to 100 micrograms per well; media collected at 24 or 48 hours, with superoxide measured at 3 hours
• Main results:
  • In RAW264.7 cells exposed to 100 micrograms of fiber for 24 hours, nitrite in the medium increased significantly for all five fibers (control 6.2 plus or minus 0.57 micromolar; chrysotile 10.6 plus or minus 0.95; crocidolite 11.5 plus or minus 1.14; glass wool 10.4 plus or minus 0.42; rock wool 8.7 plus or minus 0.75; RF1 9.4 plus or minus 0.53; n equals 4, p less than 0.01)
  • In J774 cells, nitrite increased significantly with chrysotile, glass wool or RF1, but not with crocidolite or rock wool
  • Glutathione was measured in RAW264.7 cells only; at 24 hours reduced glutathione fell significantly with chrysotile, crocidolite or glass wool and rose significantly with RF1; total glutathione fell with chrysotile or crocidolite, and GSSG rose significantly with glass wool only
  • In RAW264.7 cells the level of reduced glutathione decreased significantly with chrysotile, crocidolite or glass wool and increased significantly with RF1
  • At the lower dose (20 micrograms, 24 hours) RS-NO rose significantly in RAW264.7 medium with crocidolite, glass wool or RF1 but not chrysotile or rock wool, and in J774 medium with crocidolite, glass wool, rock wool or RF1 but not chrysotile
  • At 100 micrograms for 24 hours, RS-NO increased significantly in both cell lines with every fiber tested
  • Superoxide anion generation by RAW264.7 cells, measured 3 hours after fiber addition, increased significantly with 100 micrograms of chrysotile or rock wool, but not with crocidolite, glass wool or RF1
  • The superoxide time point was chosen from a time-course experiment with 20 micrograms chrysotile in RAW264.7 cells
• The authors' conclusion: The authors concluded that exposure of macrophages to asbestos or man-made mineral fibers produced RS-NO formation and decreased cellular glutathione, and that these forms of oxidative stress may be implicated in the development of asbestos-induced diseases
• Limitations the authors state:
  • The authors stated that they could not rule out that decreased glutathione was due to inhibited synthesis rather than consumption
  • The authors stated the mechanism of the increased glutathione after ceramic fiber (RF1) exposure remained unclear
  • The authors stated that whether thiol nitrosation affects enzyme and protein function, and whether other lung cell types respond similarly, still needs study

Topics

Medical terms in this study, explained in our Lexicon: Glutathione (GSH), Macrophage, Mineral Fiber, Chrysotile, Crocidolite, Superoxide, Oxidative Stress, Inflammation.

Related studies

• Asbestos fibers and interferon-gamma up-regulate nitric oxide production in rat alveolar macrophages — G. Thomas, T. Ando, et al. (1994)
• Mechanisms of asbestos-induced nitric oxide production by rat alveolar macrophages in inhalation and in vitro models — T.R. Quinlan, K.A. BeruBe, et al. (1998)
• Iron inhibits the nitric oxide synthesis elicited by asbestos in murine macrophages — E. Aldieri, D. Ghigo, et al. (2001)
• Regulation of nitric oxide synthase induction by iron and glutathione in asbestos-treated human lung epithelial cells — S.H. Park, A.E. Aust (1998)
• Nitric oxide (NO) synthase activity in the lung and NO synthesis in alveolar macrophages of rats increased on exposure to asbestos — H. Iguchi, S. Kojo, et al. (1996)
• Intrapleural interleukin-2 induces nitric oxide production in pleural effusions from malignant mesothelioma: a possible mechanism of interleukin-2-mediated cytotoxicity? — C. Porta, V. Rizzo, et al. (2002)

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