Mechanism of refractory ceramic fiber- and rock wool-induced cytotoxicity in alveolar macrophages

Our plain-English summary of Mechanism of refractory ceramic fiber- and rock wool-induced cytotoxicity in alveolar macrophages, by K.A. Kim, W.K. Lee, J.K. Kim, et al (International Archives of Occupational and Environmental Health, 2001).

The study

• Authors: K.A. Kim, W.K. Lee, J.K. Kim, M.S. Seo, Y. Lim, K.H. Lee, G. Chae, S.H. Lee, Y. Chung
• Journal: International Archives of Occupational and Environmental Health
• Published: 2001;74(1):9-15
• Cited by: 25 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: Man-made vitreous fibers (MMVFs) can induce cytotoxicity in a way similar to that of other particles, including silica and asbestos fibers. However, as yet the mechanism of MMVF-induced cytotoxicity is still not clear. This report aims to clarify the mechanism of MMVF-induced cytotoxicity in the alveolar macrophage (AM). In this mechanism, an attempt to prove the involvement of the adenosine triphosphate (ATP) generation system and the polyinosinic acid-inhibitable scavenger receptors was made.

Methods: Several parameters were observed for cytotoxicity, such as cell viability, the release of lactic dehydrogenase (LDH) and ATP levels in rat AM's that were treated with refractory ceramic fibers (RF2) and rock wool (RW1). A specially designed ATP generation system was used to determine the effect of MMVF on ATP generation. A scavenger receptor ligand was applied to evaluate the relationship between scavenger receptors and MMVF-induced ATP depletion.

Results: A 3-(4,5-dimethylthiazol)-2,5-diphenyl tetrazolium bromide (MTT) assay indicated that both RF2 and RW1 caused a decrease in cell viability and this decrease was concentration-dependent. RF2 and RW1 increased the release of LDH with increasing fiber concentration. From these parameters, RF2 was shown to exhibit greater cytotoxicity than did RW1. Both fibers decreased the intracellular ATP content and this decrease was concentration-dependent. The decrease was more pronounced in RW1 than in RF2 at all fiber concentrations. These fibers suppressed succinate-triggered oxygen consumption. Polyinosinic acid, a ligand of the scavenger receptor, inhibited the MMVF-induced decrease in ATP concentration.

Conclusion: These results suggest that RF2 and RW1 can induce cytotoxicity and ATP depletion in the AM through the polyinosinic acid-inhibitable scavenger receptor. ATP depletion was the important factor in MMVF cytotoxicity, especially by RW1.

In plain English

This was a laboratory (in vitro) study of two man-made vitreous fibers, refractory ceramic fiber (RF2) and rock wool (RW1). In rat alveolar macrophages the authors measured cell viability with an MTT assay, release of lactic dehydrogenase (LDH) and intracellular adenosine triphosphate (ATP) content; oxygen consumption was measured separately in mitochondria isolated from rat liver (hepatocytes) using a specially designed ATP generation system, and polyinosinic acid, a ligand of the scavenger receptor, was also tested. Both RF2 and RW1 reduced macrophage viability in a concentration-dependent way and increased LDH release as fiber concentration rose; by these measures RF2 was more cytotoxic than RW1. Both fibers lowered intracellular ATP concentration-dependently, and this decrease was more pronounced with RW1 than with RF2 at all fiber concentrations. Both fibers suppressed succinate-triggered oxygen consumption in the isolated mitochondria, and polyinosinic acid inhibited the fiber-induced fall in ATP. The authors concluded that RF2 and RW1 can induce cytotoxicity and ATP depletion in alveolar macrophages through the polyinosinic acid-inhibitable scavenger receptor, ATP depletion being an important factor especially for RW1.

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 (cell and isolated mitochondria) experiment with man-made vitreous fibers; findings taken from the PubMed abstract and figure legends because the supplied full text is unreadable
• Who was studied: Rat alveolar macrophages studied in culture, together with mitochondria isolated from rat liver (hepatocytes) for the oxygen-consumption experiment
• Exposure: Man-made vitreous fibers: refractory ceramic fiber (RF2) and rock wool (RW1), applied at varying concentrations; polyinosinic acid used as a scavenger receptor ligand
• Main results:
  • The MTT assay showed that both RF2 and RW1 caused a concentration-dependent decrease in cell viability of the alveolar macrophages
  • RF2 and RW1 increased LDH release with increasing fiber concentration; by these parameters RF2 was more cytotoxic than RW1
  • Both fibers decreased intracellular ATP content in the alveolar macrophages concentration-dependently, with the decrease more pronounced for RW1 than RF2 at all fiber concentrations
  • Both fibers suppressed succinate-triggered oxygen consumption in mitochondria of rat hepatocytes, and polyinosinic acid inhibited the fiber-induced decrease in ATP concentration
• The authors' conclusion: The authors concluded that RF2 and RW1 can induce cytotoxicity and ATP depletion in the alveolar macrophage through the polyinosinic acid-inhibitable scavenger receptor, and that ATP depletion was an important factor in the cytotoxicity of these fibers, especially for RW1

Topics

Medical terms in this study, explained in our Lexicon: Alveolar Macrophage, Vitreous.

Related studies

• Refractory ceramic fibers activate alveolar macrophage eicosanoid and cytokine release — G.D. Leikauf, S.P. Fink, et al. (1995)
• Cytotoxicity study of rock wool by cell magnetometric evaluation — Y. Kudo, M. Kotani, et al. (2009)
• Comparative cytotoxicity study of rock wool and chrysotile by cell magnetometric evaluation — Y. Kudo, M. Watanabe, et al. (2003)
• Perspectives on refractory ceramic fiber (RCF) carcinogenicity: comparisons with other fibers — H. Greim, M.J. Utell, et al. (2014)
• Refractory ceramic fiber exposure and pleural plaques — J. Lockey, G. Lemasters, et al. (1996)
• Refractory ceramic fiber (RCF) toxicity and epidemiology: a review — M.J. Utell, L.D. Maxim (2010)

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