Iron and Iron-Related Proteins in Asbestosis

Our plain-English summary of Iron and Iron-Related Proteins in Asbestosis, by A.J. Ghio, E.N. Pavlisko, V.L. Roggli (Journal of Environmental Pathology, Toxicology and Oncology, 2015).

The study

• Authors: A.J. Ghio, E.N. Pavlisko, V.L. Roggli
• Journal: Journal of Environmental Pathology, Toxicology and Oncology
• Published: 2015;34(4):277-85
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

We tested the postulate that iron homeostasis is altered among patients diagnosed to have asbestosis. Lung tissue from six individuals diagnosed to have had asbestosis at autopsy was stained for iron, ferritin, divalent metal transporter 1 (DMT1), and ferroportin 1 (FPN1). Slides from six individuals having pneumonectomy for lung cancer were employed as controls. Lung tissue from those patients with asbestosis demonstrated stainable iron, whereas control lung tissue did not. Staining for this metal was observed predominantly in airway and alveolar macrophages. Expression of the iron-related proteins ferritin, DMT1, and FPN1 was elevated in lung tissue from the six asbestosis patients relative to controls. This increased expression of iron-transport and iron-storage proteins was evident in both airway and alveolar epithelial cells. Asbestos bodies were abundant in lung tissue from patients diagnosed to have had asbestosis. While staining for iron, ferruginous bodies did not demonstrate uptake of antibodies for ferritin, DMT1, and FPN1. We conclude that iron homeostasis is altered in lung disease among those diagnosed to have asbestosis with an accumulation of the metal and a modified expression of iron-related proteins being evident.

In plain English

The authors examined autopsy lung tissue from six people diagnosed with asbestosis. The cases came from an existing cohort of patients with recognized fiber exposure, and none had lung cancer. For comparison, they used lung tissue removed during surgery (pneumonectomy) from six people with lung cancer, none of whom had asbestosis. The article does not say which asbestos fiber types the patients were exposed to, or how much. Slides were stained for iron and for three proteins that store or move iron: ferritin, DMT1 and FPN1. The asbestosis lungs showed inflammation and scarring, and the authors described collagen as significantly increased. Iron stained abundantly in the asbestosis lungs, mostly in alveolar macrophages, but did not stain in the control tissue. Ferritin, DMT1 and FPN1 were all increased in the asbestosis lungs compared with controls. Asbestos bodies stained for iron but showed no significant staining for any of the three proteins. The authors concluded that the lungs' normal handling of iron is altered in people diagnosed with asbestosis. They noted that the iron stain used is insensitive.

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: Pathology study comparing stained archived lung tissue (iron stain and immunohistochemistry) from asbestosis autopsy cases with lung tissue from lung cancer surgery controls
• Who was studied: Six individuals diagnosed with asbestosis, identified from an existing cohort of patients with recognized fiber exposure, whose lung tissue was collected at autopsy. None of them had lung cancer. Controls were six individuals who had pneumonectomy for lung cancer, none diagnosed with asbestosis. The study was approved by the Duke University Institutional Review Board. Dates are not given.
• Exposure: Asbestos fiber exposure (recognized fiber exposure leading to asbestosis). Fiber types, jobs and doses for the patients are not reported.
• Main results:
  • Asbestosis lungs showed patchy inflammation and fibrosis, and the authors described collagen deposition as significantly increased in them. Control lungs showed little to no inflammation.
  • In the asbestosis lungs, stainable iron was abundant in the lower respiratory tract, in higher concentrations in alveolar macrophages.
  • Iron did not stain in the control lung tissue.
  • In the asbestosis lungs, ferritin (an iron-storage protein) was increased in all cell types, with the greatest increase in alveolar macrophages.
  • DMT1 (an iron importer) was present in control tissue but elevated in the asbestosis lungs, most evidently in alveolar macrophages.
  • FPN1 (an iron exporter) was increased in the asbestosis lungs.
  • Asbestos bodies stained positively for iron. After comparison with unstained sections, the authors concluded they showed no significant staining for ferritin, DMT1 or FPN1.
• The authors' conclusion: The authors concluded that iron homeostasis (the body's normal handling of iron) is altered in the lungs of people diagnosed with asbestosis, with iron accumulating and iron-related proteins being expressed differently.
• Limitations the authors state:
  • The authors stated that the Perls' iron stain is insensitive, so a lack of iron staining (for example in epithelial cells) does not mean iron was absent.

Topics

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

Medical terms in this study, explained in our Lexicon: Autopsy, Ferritin, Pneumonectomy, Lung Cancer, Alveolar Macrophage, Asbestos Bodies, Ferruginous Bodies.

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• Asbestos and Iron — A.J. Ghio, M. Stewart, et al. (2023)
• Synchrotron X-ray microscopy reveals early calcium and iron interaction with crocidolite fibers in the lung of exposed mice — L. Pascolo, G. Zabucchi, et al. (2016)
• The role of iron in Libby amphibole-induced acute lung injury and inflammation — J.H. Shannahan, A.J. Ghio, et al. (2011)
• The biological effect of asbestos exposure is dependent on changes in iron homeostasis — A.J. Ghio, J.M. Soukup, et al. (2016)

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