Lipid peroxidation and disintegration of the cell membrane structure in cultures of rat lung fibroblasts treated with asbestos

Our plain-English summary of Lipid peroxidation and disintegration of the cell membrane structure in cultures of rat lung fibroblasts treated with asbestos, by H. Iguchi, S. Kojo, M. Ikeda (Journal of Applied Toxicology, 1993).

The study

• Authors: H. Iguchi, S. Kojo, M. Ikeda
• Journal: Journal of Applied Toxicology
• Published: 1993;13(4):269-75
• Cited by: 43 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Rat lung fibroblasts were cultured for 24 and 48 h with UICC standard reference asbestos samples of amosite, crocidolite or Canadian chrysotile at various concentrations, and thiobarbituric acid-reactive substances (TBARS) in the media and the cells were measured. Tests by the trypan blue dye-exclusion method showed that cell viability was 80 +/- 5% (mean +/- SD) and 71 +/- 6% when cultured for 48 h in the presence of 500 micrograms ml-1 of amosite and crocidolite, respectively, but was not affected by chrysotile. In cultures for 24 and 48 h, both chrysotile and crocidolite at > 250 micrograms ml-1 significantly increased TBARS in the medium, whereas amosite did so at > 500 micrograms ml-1. TBARS in the cells was not increased significantly by chrysotile at any concentration in the cultures for 24 and 48 h, but crocidolite at > 250 micrograms ml-1 significantly increased TBARS in the cells when cultured for 24 or 48 h. Although amosite at all concentrations tested did not increase significantly TBARS in the cells of the 24-h culture, it did increase TBARS significantly in the cells when cultured for 48 h at a concentration of 500 micrograms ml-1 amosite. The increases of TBARS in media of the cultures with asbestos were accompanied by increases of lactate dehydrogenase (LDH) activity in the media, indicating the leakage of the enzyme from the cell into the media. The activity of LDH and the amount of TBARS showed a good correlation with each other, with a significant correlation coefficient value of 0.655.(ABSTRACT TRUNCATED AT 250 WORDS)

In plain English

In this laboratory experiment, the authors grew lung fibroblasts from rat embryos and exposed them to UICC standard reference samples of amosite, crocidolite or Canadian chrysotile at 50 to 1000 micrograms per millilitre, alongside unexposed cultures. They measured TBARS, a measure of lipid peroxidation (oxidative damage to fats), and leakage of the cell enzyme LDH into the culture medium. After 48 hours at 500 micrograms per millilitre, cell viability fell to 80% with amosite and 71% with crocidolite; chrysotile did not affect viability even at 1000. At higher concentrations all three fibers significantly increased TBARS in the medium; none did at 50. Inside the cells, significant TBARS increases appeared only at higher concentrations: crocidolite at 24 and 48 hours, amosite only at 48 hours; chrysotile caused no significant increase at any concentration tested. LDH in the medium rose most with chrysotile, but it was measured in only two dishes per condition and was not tested statistically. LDH and TBARS were correlated (coefficient 0.655, statistically significant). The authors concluded that certain types of asbestos peroxidized the cell membranes, disrupting them so that LDH leaked out.

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
• Who was studied: Lung fibroblasts isolated from the embryos of a pregnant rat on day 20 of gestation and grown in culture through eight passages. Four culture dishes were used at each concentration of each asbestos type, with the same number of asbestos-free control dishes.
• Exposure: UICC standard reference samples of Canadian chrysotile, amosite and crocidolite, each tested separately at 0, 50, 250, 500 and 1000 micrograms per millilitre of medium, for 12, 24 or 48 hours. Results for 12 hours were not shown.
• Main results:
  • Cell viability after 48 hours at 500 micrograms per millilitre fell to 80 plus or minus 5.0% with amosite and 71 plus or minus 6.0% with crocidolite, compared with the asbestos-free control culture. Chrysotile at 1000 micrograms per millilitre did not affect viability.
  • In the 24-hour cultures, none of the three asbestos types significantly affected cell viability.
  • In the 24-hour cultures, TBARS in the medium rose significantly with crocidolite at concentrations higher than 250 micrograms per millilitre. With chrysotile and amosite it rose significantly at 500 micrograms per millilitre but not at 250.
  • In the 48-hour cultures, TBARS in the medium was significantly higher than in controls with chrysotile or crocidolite at 250 micrograms per millilitre or more, and with amosite at 500 micrograms per millilitre.
  • At 50 micrograms per millilitre, none of the asbestos types increased TBARS in the medium at either 24 or 48 hours.
  • In the cells at 24 hours, crocidolite at concentrations higher than 250 micrograms per millilitre significantly increased TBARS compared with asbestos-free cultures. Chrysotile and amosite did not increase TBARS significantly at any concentration.
  • In the cells at 48 hours, amosite (above 250 micrograms per millilitre in the Results text, 500 in the abstract) and crocidolite (500 micrograms per millilitre in the Results text) significantly increased TBARS compared with controls. Chrysotile did not significantly increase TBARS in the cells at any concentration in either the 24-hour or 48-hour cultures.
  • LDH activity in the medium increased markedly with chrysotile at concentrations above 250 micrograms per millilitre at 24 or 48 hours. The increase was smaller with crocidolite, and amosite at 500 micrograms per millilitre or more showed only a tendency to increase. These LDH data were not analysed statistically.
  • LDH activity and TBARS in the medium were correlated, with a correlation coefficient of 0.655, which was statistically significant (P less than 0.05).
• The authors' conclusion: The authors concluded that when certain types of asbestos are cultured with rat lung fibroblasts, the cell membranes are peroxidized and their structure disintegrates, followed by leakage of LDH from the cells into the medium. Their final paragraph names crocidolite and amosite in this conclusion.
• Limitations the authors state:
  • LDH activity was measured in only two of the four dishes per condition, so no further statistical analysis of LDH was done.
  • The TBA test used to measure lipid peroxidation has known drawbacks. The authors nonetheless adopted it because it correlates well with other measures.
  • Whether iron in the asbestos plays an essential role in the lipid peroxidation observed remained unresolved.

Topics

Medical terms in this study, explained in our Lexicon: Fibroblast, UICC, Amosite, Crocidolite, Chrysotile, Lactate Dehydrogenase (LDH).

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