Diallylsulfide attenuates asbestos-induced genotoxicity

Our plain-English summary of Diallylsulfide attenuates asbestos-induced genotoxicity, by M. Lohani, S. Yadav, D. Schiffmann, et al (Toxicology Letters, 2003).

The study

• Authors: M. Lohani, S. Yadav, D. Schiffmann, Q. Rahman
• Journal: Toxicology Letters
• Published: 2003;143(1):45-50
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

It is well known that asbestos fibers induced genotoxicity is mediated by reactive oxygen species (ROS) and insufficient endogenous antioxidant protection. Asbestos exposure can result in ROS generation in two different ways: (a) by catalyzation of Fe(2+), which is present in asbestos fibers, and (b) via oxidative bursts during phagocytosis of the fibers. On the other hand, it has been discussed that the physical presence of the fibres may mechanically influence the normal segregation of chromosomes during mitosis resulting in the induction of micronuclei in late ana/telophase, and aneuploidy. Glutathione and the glutathione redox system protect cells from the oxidative damage after exposure to xenobiotics. Glutathione depletion occurs during oxidative stress conditions and it is observed that supplementation of a precursor of glutathione and other sulphur containing compounds results in reduced toxicity. In the present study, diallyl sulfide (DAS), a lipid soluble allyl sulphur compound present in fresh extracts of garlic was evaluated for its protective effects. The micronucleus (MN) assay was performed in human mesothelial cells (HMC) exposed to 1 microg/cm(2) of crocidolite and chrysotile. Simultaneously, the cells were treated with 5 and 10 microM DAS, incubated for 48 and 66 h. Asbestos fibers induced significant genetic damage in HMC. The assay revealed a significant reduction in MN induction after treatment of cells with 5 microM but not with 10 microM DAS in mesothelial cells. The study revealed that at appropriate concentrations DAS protects mesothlelial cells against asbestos induced genotoxicity.

In plain English

This laboratory study tested whether diallyl sulfide (DAS), a sulphur compound found in fresh garlic extracts, protected human mesothelial cells from genetic damage caused by asbestos. The cells came from the ascites fluid of a non-cancerous patient at the university hospital in Rostock, Germany, and were grown in culture. They were exposed to crocidolite or chrysotile fibers, with or without DAS at two concentrations. They were then examined for micronuclei, small extra nuclei that are a sign of chromosome damage. Both fiber types raised micronuclei well above untreated cells. Crocidolite produced a mean of 40 and 41.20 per 1000 cells at 48 and 66 hours, and chrysotile 37.5 and 40, compared with 12 and 15 in controls. The lower DAS concentration reduced these counts (for example, chrysotile-exposed cells to 27 and 25.83), but not to control levels. The higher concentration gave less protection. On its own, the higher concentration raised micronuclei in cells not exposed to asbestos to 22.5 per 1000 at 66 hours. The authors concluded that at appropriate concentrations DAS protects mesothelial cells against asbestos-induced genotoxicity. The study used cultured cells only.

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) experiment using the micronucleus assay in cultured human mesothelial cells
• Who was studied: Human mesothelial cells grown in culture, obtained from the ascites fluid of one non-cancerous patient at the university hospital in Rostock, Germany. Only first- and second-passage cells were used. Each data point was the mean of 3 treated cultures from different experiments, with 2000 nuclei evaluated in each.
• Exposure: Crocidolite and chrysotile fibers at 1 microgram per square centimetre, according to the PubMed abstract (the extracted text reads '1 mg/cm2'). Cells were treated at the same time with diallyl sulfide at 5 and 10 micromolar (the extracted text reads '5 and 10 mM') and incubated for 48 and 66 hours.
• Main results:
  • Asbestos alone raised micronucleus frequency. Crocidolite-exposed cells had a mean of 40 per 1000 cells at 48 h and 41.20 at 66 h. Chrysotile-exposed cells had 37.5 at 48 h and 40 at 66 h. Both were significantly higher (P less than 0.001) than controls.
  • Untreated control cells had a mean of 12 micronuclei per 1000 cells at 48 h and 15 at 66 h.
  • With the lower DAS concentration, micronuclei were reduced in chrysotile-exposed cells (mean 27 per 1000 at 48 h; 25.83 at 66 h) and in crocidolite-exposed cells (29 at 48 h; 29.5 at 66 h).
  • DAS did not bring micronucleus frequency in asbestos-exposed cells back to the baseline level.
  • With the higher DAS concentration there was less protection. Crocidolite-exposed cells had means of 33.5 per 1000 at 48 h and 31 at 66 h. Chrysotile-exposed cells had 29.5 at 48 h and 31 at 66 h.
  • DAS alone at the lower concentration caused no significant change in micronuclei (means 14.25 per 1000 at 48 h; 10.0 at 66 h). At the higher concentration it significantly raised micronuclei (P less than 0.001), to a mean of 22.5 per 1000 at 66 h.
• The authors' conclusion: The authors concluded that, at appropriate concentrations, DAS protects mesothelial cells against asbestos-induced genotoxicity. They further proposed that excess reactive oxygen species after asbestos exposure may deplete glutathione, and that sulphur compounds may raise glutathione and so reduce asbestos-mediated genotoxicity. Glutathione was not measured in this study.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile, Crocidolite.

Medical terms in this study, explained in our Lexicon: Genotoxicity, Reactive Oxygen Species (ROS), Asbestos Exposure, Phagocytosis, Micronuclei, Glutathione (GSH), Oxidative Stress, Mesothelial Cells.

Related studies

• Smoking enhances asbestos-induced genotoxicity, relative involvement of chromosome 1: a study using multicolor FISH with tandem labeling — M. Lohani, E. Dopp, et al. (2002)
• Reduction of chrysotile asbestos-induced genotoxicity in human peripheral blood lymphocytes by garlic extract — K. Bhattacharya, S. Yadava, et al. (2004)
• Environmental toxicants--induced epigenetic alterations and their reversers — M. Kim, M. Bae, et al. (2012)
• A study of the effect of chrysotile fiber surface composition on genotoxicity in vitro — M.J. Keane, J.W. Stephens, et al. (1999)
• Chemical interaction: enhancement and inhibition of clastogenicity — W.A. Anwar (1993)
• Mechanisms of fiber-induced genotoxicity — M.C. Jaurand (1997)

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