In vitro interaction of zeolite fibers with individual cells (macrophages NR8383): measurement of intracellular oxidative burst

Our plain-English summary of In vitro interaction of zeolite fibers with individual cells (macrophages NR8383): measurement of intracellular oxidative burst, by B.D. Hogg, P.K. Dutta, J.F. Long (Analytical Chemistry, 1996).

The study

• Authors: B.D. Hogg, P.K. Dutta, J.F. Long
• Journal: Analytical Chemistry
• Published: 1996;68(14):2309-12
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Inhalation of fibrous minerals such as asbestos and erionite can cause various lung diseases, including cancer. The mechanism by which these fibers induce disease is an area of active research. Interaction of fibers with lung macrophages leads to release of many substances. Among these, reactive oxygen metabolites (which include hydrogen peroxide, superoxide, and possibly hydroxyl radicals) are proposed to cause cellular damage. In this paper, we report a method for observing intracellular hydrogen peroxide release as rat lung-derived macrophages (NR-8383) phagocytize erionite fibers. This is possible by observing the fluorescence of 2',7'-dichlorofluorescein-the intracellular, oxidized form of 5 (and 6)-carboxy-2', 7'-dichlorodihydrofluorescin formed in the presence of newly released hydrogen peroxide. We are able to image the fluorescence within a single cell, thereby allowing us to get information on the spatial distribution of the metabolites.

In plain English

This laboratory study developed a method for watching, inside a single cell, the release of hydrogen peroxide and related reactive oxygen substances (the 'oxidative burst') as immune cells swallow mineral fibers. The authors used NR8383, a cell line derived from rat lung alveolar macrophages, and erionite, a fibrous zeolite mineral from deposits in the northwestern United States. They chose erionite partly because earlier studies, cited in their introduction, linked it to pleural and peritoneal mesothelioma in humans. Cells were loaded with a dye that glows when oxidized, exposed to small erionite fibers (under 10 µm long), and imaged with a laser microscope. A fiber was seen inside a macrophage. Thirty minutes after warming, an erionite-exposed cell glowed more strongly than a control cell, though the control's signal was not zero. In an exposed cell the glow was uneven, while in control cells it was fairly uniform. The authors concluded that the oxidative burst in a single macrophage can be monitored. They noted the method cannot yet deliver one specific fiber to a cell, so a cell may take up several fibers and dust particles.

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: Laboratory (in vitro) cell-culture experiment describing a new measurement method
• Who was studied: NR8383, a cell line derived from rat pulmonary alveolar macrophages, compared with unexposed control cells. The number of cells analyzed is not stated.
• Exposure: Naturally occurring erionite, a fibrous zeolite, from deposits in the northwestern United States. Only small fibers (length under 10 µm) were selected. Cells received about 1.4 million particles per mL in suspension. The sample also contained smaller colloidal dust.
• Main results:
  • An optical micrograph showed a fiber inside a macrophage, indicating that the cells had engulfed (phagocytized) fibers.
  • Imaged 30 minutes after warming, the erionite-exposed cell showed stronger fluorescence than the control cell. The authors took this as indicating higher intracellular peroxide levels.
  • The control cell also showed some fluorescence. The authors noted that other researchers had attributed such background signal to factors such as mitochondrial respiration.
  • In thin cross sections of an erionite-exposed cell, the oxidized dye was unevenly distributed. In control cells the fluorescence was quite uniform.
• The authors' conclusion: The authors concluded that the oxidative burst within a single macrophage interacting with erionite fibers can be monitored. They stated that locating the fluorescence within the cell is an advantage over flow cytometry.
• Limitations the authors state:
  • The technique cannot introduce a single, specific fiber into the cell.
  • Because of how cells were exposed, a single cell may engulf multiple fibers as well as colloidal particles from the sample. The authors suggested this may explain the uneven fluorescence.
  • The authors cautioned that any link between oxidant release in such in vitro tests and the development of toxicity must be drawn carefully.

Topics

Medical terms in this study, explained in our Lexicon: Zeolite, Macrophage, erionite, Superoxide, Hydroxyl Radical.

Related studies

• Enhancement of the macrophage oxidative burst by immunoglobulin coating of respirable fibers: fiber-specific differences between asbestos and man-made fibers — I.M. Hill, P.H. Beswick, et al. (1996)
• Analysis of the biological and chemical reactivity of zeolite-based aluminosilicate fibers and particulates — E. Fach, W.J. Waldman, et al. (2002)
• Production of reactive oxygen intermediates by human macrophages exposed to soot particles and asbestos fibers and increase in NF-kappa B p50/p105 mRNA — R. Oettinger, K. Drumm, et al. (1999)
• In vitro activity of silicon carbide whiskers in comparison to other industrial fibers using four cell culture systems — N.F. Johnson, M.D. Hoover, et al. (1992)
• Activation of alveolar macrophages and peripheral red blood cells in rats exposed to fibers/particles — F. Afaq, P. Abidi, et al. (1998)
• Pulmonary cell interactions with asbestos fibers in vivo and in vitro — A.R. Brody (1986)

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