Activation of alveolar macrophages and peripheral red blood cells in rats exposed to fibers/particles

Our plain-English summary of Activation of alveolar macrophages and peripheral red blood cells in rats exposed to fibers/particles, by F. Afaq, P. Abidi, R. Matin, et al (Toxicology Letters, 1998).

The study

• Authors: F. Afaq, P. Abidi, R. Matin, Q. Rahman
• Journal: Toxicology Letters
• Published: 1998;99(3):175-82
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The cytotoxic and oxidative responses of crocidolite and chrysotile asbestos fibers and ultrafine titanium dioxide (UF-TiO2) particles were measured in alveolar macrophages (AM) and peripheral red blood cells (RBC) of rat after 30 days with a single intratracheal exposure (5 mg). The following responses were observed one month after fiber/particle instillation: (1) AM population increased; (2) lactate dehydrogenase and acid phosphatase activities in cell free lung lavage fluid increased; (3) substances that react with hydrogen peroxide or thiobarbituric acid were elevated in both AM and peripheral RBC; (4) glutathione peroxidase, glutathione reductase, and catalase were altered in both AM and peripheral RBC; (5) glutathione and ascorbic acid decreased in both AM and peripheral RBC. A significant difference from negative controls was noted in all responses of the two fiber-exposed groups, and in most responses of the UF-TiO2-exposed group. The level of responses to the three test substances suggested a decreasing order of toxicity, with crocidolite > chrysotile > UF-TiO2.

In plain English

This was an animal experiment at the Industrial Toxicology Research Centre in Lucknow, India. Female albino rats were split into four groups. Three groups received a single 5 mg dose, placed into the windpipe, of UICC crocidolite asbestos, Indian chrysotile asbestos, or ultrafine titanium dioxide particles. The fourth group received saline only. One month later the authors measured signs of cell damage and oxidative stress in lung-washing fluid, in alveolar macrophages (lung defence cells) and in red blood cells. Compared with controls, macrophage numbers rose by 50% with crocidolite, 48% with chrysotile and 32% with titanium dioxide. A marker of damage to cell fats rose in macrophages in all three groups, and in red blood cells with the two asbestos types. Some protective substances, such as glutathione, fell. Several titanium dioxide changes were not statistically significant. The authors reported a ranking of crocidolite, then chrysotile, then titanium dioxide, but stated that the differences between crocidolite and chrysotile were not significant. They concluded that the red blood cell changes reflected the lung changes.

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: Animal experiment (single intratracheal instillation in rats, with a saline control group, examined one month after exposure)
• Who was studied: Female albino rats from the Industrial Toxicology Research Centre breeding colony, Lucknow, India, divided into four groups (three exposed, one saline control). Figure and table legends give n=6 per group.
• Exposure: A single intratracheal dose of 5 mg in 0.5 ml saline of UICC crocidolite, Indian chrysotile (mined at Cuddapah, Andhra Pradesh) or ultrafine titanium dioxide. Animals were sacrificed one month after exposure.
• Main results:
  • Compared with controls, the number of alveolar macrophages increased by 50% with crocidolite, 48% with chrysotile and 32% with ultrafine titanium dioxide.
  • In cell-free lung lavage fluid, LDH activity increased by 36% (crocidolite), 35% (chrysotile) and 17% (ultrafine titanium dioxide).
  • In cell-free lung lavage fluid, acid phosphatase activity increased by 77% (chrysotile), 66% (crocidolite) and 42% (ultrafine titanium dioxide).
  • In alveolar macrophages, thiobarbituric acid reactive substances (a lipid peroxidation marker) increased by 107% (crocidolite), 95% (chrysotile) and 43% (ultrafine titanium dioxide).
  • In alveolar macrophages, hydrogen peroxide generation increased by 59% (crocidolite), 53% (chrysotile) and 22% (ultrafine titanium dioxide).
  • In red blood cells, lipid peroxidation increased significantly with crocidolite (49%) and chrysotile (38%). The increase with ultrafine titanium dioxide was not significant.
  • In alveolar macrophages, glutathione peroxidase activity decreased significantly by 18% (crocidolite) and 14% (chrysotile). Glutathione reductase decreased by 22% and 12% respectively. Decreases with ultrafine titanium dioxide were not significant.
  • In red blood cells, glutathione peroxidase activity decreased by 37% (chrysotile) and 21% (crocidolite), with no significant change for ultrafine titanium dioxide.
  • In red blood cells, catalase activity decreased by 43% (crocidolite), 42% (chrysotile) and 30% (ultrafine titanium dioxide).
  • Glutathione in alveolar macrophages fell in all three exposed groups: 36% (crocidolite), 32% (chrysotile) and 25% (ultrafine titanium dioxide).
  • Ascorbic acid in alveolar macrophages fell significantly with crocidolite (22%) and chrysotile (21%) but not with ultrafine titanium dioxide.
  • In red blood cells, glutathione and ascorbic acid decreased most with crocidolite, then chrysotile, with no significant change for ultrafine titanium dioxide.
  • Responses were largest with crocidolite, followed by chrysotile, but the differences between crocidolite and chrysotile were not statistically significant.
• The authors' conclusion: The authors concluded that, at an early stage, the cytotoxic, inflammatory and oxidative responses seen in alveolar macrophages were also reflected in peripheral red blood cells. They suggested these biomarkers may be used to compare fibers and particles. They also concluded that ultrafine titanium dioxide induced far less toxicity than either asbestos fiber.

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: Alveolar Macrophage, Crocidolite, Chrysotile, Lactate Dehydrogenase (LDH), Glutathione (GSH).

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