Expression of heme oxygenase-1 in the lungs of rats exposed to crocidolite asbestos

Our plain-English summary of Expression of heme oxygenase-1 in the lungs of rats exposed to crocidolite asbestos, by H. Nagatomo, Y. Morimoto, T. Oyabu, et al (Inhalation Toxicology, 2005).

The study

• Authors: H. Nagatomo, Y. Morimoto, T. Oyabu, M. Hirohashi, A. Ogami, H. Yamato, K. Kuroda, T. Higashi, I. Tanaka
• Journal: Inhalation Toxicology
• Published: 2005;17(6):293-6
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Oxidative stress is thought to be the pathogenesis of pulmonary fibrosis induced by asbestos, and heme oxygenase-1 (HO-1) protects lung tissue against oxidative stress. We hypothesized that HO-1 is associated with oxidative lung injury caused by exposure to asbestos. This study was conducted to investigate the time course of HO-1 expression of lungs exposed to crocidolite asbestos in vivo. Male Wistar rats were administered 1 mg or 2 mg crocidolite asbestos suspended in saline by a single intratracheal instillation and were sacrificed at 3 d, 1 wk, 1 mo, 3 mo, and 6 mo of recovery time. The expression of HO-1 was observed by Western blot analysis and immunostaining. Protein levels of HO-1 increased at from 3 d to 6 mo following intratracheal instillation of 2 mg crocidolite asbestos. The levels of HO-1 increased at 1 wk and 1 mo following intratracheal instillation of 1 mg crocidolite asbestos. Many HO-1-positive cells were found, particularly in the alveolar macrophages, during immunostaining. These findings suggest that HO-1 may be related to lung disorder induced by dust and therefore can act as a biomarker of lung injury due to dust exposure.

In plain English

This was an animal experiment from Japan. The authors gave 10-week-old male Wistar rats a single dose of 1 mg or 2 mg crocidolite asbestos in saline into the windpipe. Control rats received saline. Groups of five rats were examined at 3 days, 1 week, 1 month, 3 months and 6 months. The authors measured heme oxygenase-1 (HO-1), a protein that helps defend tissue against oxidative stress. With 2 mg crocidolite, HO-1 rose at every time point from 3 days to 6 months, most clearly at 6 months. With 1 mg, the results section reports a rise at 1 week and 3 months. Comparison rats given 1 or 2 mg titanium dioxide, examined only at 6 months, showed no significant change. At 6 months after 2 mg, the lungs showed inflammatory cells and a thickened interstitium, the tissue between the air sacs. HO-1 staining was found mainly in alveolar macrophages, immune cells inside the air sacs. The authors concluded that HO-1 appears to be involved in lung injury caused by crocidolite and may act as a biomarker of dust-related lung injury.

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 serial sacrifice over time)
• Who was studied: Male Wistar rats, 10 weeks old, from Kyudo (Kumamoto, Japan). There were exposed and control groups of 5 rats each for each exposure category, examined at 3 days, 1 week, 1 month, 3 months and 6 months.
• Exposure: UICC crocidolite asbestos, 1 mg or 2 mg in 0.4 ml saline, given once by intratracheal instillation. The fibers had a geometric mean diameter of 0.2 micrometres and a geometric mean length of 1.3 micrometres. Saline was the control. Titanium dioxide (rutile), 1 mg or 2 mg, was a negative control, examined only at 6 months.
• Main results:
  • In rats given 2 mg crocidolite, HO-1 protein increased from 3 days to 6 months after instillation. The difference was most significant at 6 months.
  • In rats given 1 mg crocidolite, the results section reports increased HO-1 protein at 1 week and 3 months.
  • Rats given 1 or 2 mg titanium dioxide were examined at a single time point, 6 months after exposure. They showed no significant change in HO-1. The data were not shown.
  • At 6 months after 2 mg crocidolite, HO-1 staining was intense mainly in alveolar macrophages compared with controls. Some bronchial and alveolar epithelial cells also stained positive.
  • At 6 months, crocidolite-exposed lungs showed inflammatory cell infiltration and a thickened interstitium. Crocidolite fibers were seen in alveolar macrophages and in the thickened interstitium.
• The authors' conclusion: The authors concluded that the rise in HO-1 suggests HO-1 is involved in lung injury caused by crocidolite exposure. They also suggested that HO-1 may serve as a biomarker of lung injury due to dust exposure.

Topics

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

Medical terms in this study, explained in our Lexicon: Crocidolite, Oxidative Stress, Pulmonary Fibrosis, Alveolar Macrophage, Biomarker.

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