Acute lung response to amosite asbestos: a morphological study

Our plain-English summary of Acute lung response to amosite asbestos: a morphological study, by R.F. Dodson, M.G. Williams, G.A. Hurst (Environmental Research, 1983).

The study

• Authors: R.F. Dodson, M.G. Williams, G.A. Hurst
• Journal: Environmental Research
• Published: 1983;32(1):80-90
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The acute morphological response to amosite asbestos in the guinea pig was studied by light microscopy and by transmission, scanning, and scanning transmission electron microscopy. Fiber identification was carried out by energy dispersive X-ray analysis. Animals were studied at postinjection intervals of 2, 4, and 12 hr and 1-7 days. Three groups of test animals were studied for each time interval. These consisted of a vascularly perfused parenchymal group and a free cell lavaged group. The information obtained was compared with saline-injected and normal control animals. The acute tissue response was characterized by intraalveolar, not interstitial, events. The early phagocytic response was shared between polymorphs and macrophages, while in the longer intervals, the macrophages were the phagocytic cell type. Packaging differences within the two types of phagocytes were seen. Endothelial stability was noted, while some edematous type I pneumocytes were observed. Fibrotic involvement was limited to some intraalveolar fibrin deposits. It is suggested that the term "free asbestos fibers" refers to an extracellular event, while intracellular fibers are coated with either a membranous sheath, a siderosome, or a classical ferruginous coating.

In plain English

This was an animal experiment in guinea pigs. It examined the lung's reaction during the week after amosite asbestos was placed in the windpipe. Exposed animals received 17.5 mg of ground commercial-grade amosite in saline. Comparison animals received saline after a sham operation or were normal controls. Lung tissue and washed-out lung cells were examined by light and electron microscopy from 2 hours to 7 days later. The authors did not state how many animals were used. Neutrophils (white blood cells) arrived within 2 hours and were the main fiber-engulfing cells on day 1. Macrophages took over that role afterwards. By day 3, most free fibers had been taken up or cleared. Some type I pneumocytes, thin cells lining the air sacs, became swollen. Cells and fluid built up in patches inside the air sacs. These patches varied in severity, and their extent correlated well with local fiber numbers. Fibrin strands also formed there. No interstitial changes were seen. The authors concluded that uncoated fibers lay outside cells, while all fibers inside cells were coated by a membrane sheath, a siderosome or a classical ferruginous coating.

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 (morphological study using light and electron microscopy)
• Who was studied: Guinea pigs exposed to amosite and examined at 2, 4 and 12 hours and 1 to 7 days after injection. Exposed animals were studied either by lung washing (lavage) or through perfusion-fixed lung tissue. They were compared with sham-operated saline-injected animals and normal controls. The number of animals was not stated.
• Exposure: A single intratracheal dose of 17.5 mg of ground commercial-grade amosite asbestos suspended in physiological saline. The article states that most fibers were below 10 (unit garbled in the scan) in length.
• Main results:
  • Energy dispersive X-ray analysis found that the commercial amosite preparation contained minimal amounts of contaminants (aluminosilicates, potassium aluminosilicates, titanium dioxide and ferroaluminosilicates).
  • In exposed animals, neutrophils were called up as early as 2 hours after injection and were the main fiber-engulfing cells during the first day. Macrophages became the chief engulfing cells afterwards.
  • By the third day, most free asbestos fibers had been taken up by engulfing cells or cleared from the air spaces.
  • Inside macrophages, some fibers were enclosed in iron-rich bodies called siderosomes. Macrophages in reactive areas that contained no asbestos also showed large numbers of siderosomes. Iron-staining material was also present in macrophages of control lung.
  • Some type I pneumocytes showed swelling (edema) of their cytoplasm. The changes were evident from 1 day after exposure and were seen in animals from every time frame.
  • Type II pneumocytes remained unchanged throughout the study.
  • Increased cellularity embedded in exudate developed inside the air sacs from 2 hours through 7 days. The response was focal and varied in severity, and its extent correlated well with the number of fibers present in each spot.
  • No interstitial changes were observed during the 7-day study. Through 7 days, the responses were confined to the air spaces.
  • A fibrous reaction made of fibrin bundles inside the air sacs was seen as early as 2 hours after exposure.
  • Extensive areas of bleeding were not found in any of the animals, although scattered red blood cells were seen inside the air sacs.
• The authors' conclusion: The authors concluded that, in living tissue, uncoated fibers are extracellular, while all intracellular fibers are coated, either by a membranous sheath, a siderosome, or a classical ferruginous coating.

Topics

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

Medical terms in this study, explained in our Lexicon: Amosite, Transmission Electron Microscopy (TEM), Fiber Identification, Interstitial, Polymorphs, Macrophage.

Related studies

• The influence of amosite asbestos exposure on lung permeability — R.F. Dodson, T. Akematsu, et al. (1984)
• Lung cell reactions in guinea pigs after inhalation of asbestos (amosite) — M. Sjöstrand, R. Rylander, et al. (1989)
• Quantification of the pathological response and fate in the lung and pleura of chrysotile in combination with fine particles compared to amosite-asbestos following short-term inhalation exposure — D.M. Bernstein, R.A. Rogers, et al. (2011)
• The pathological response and fate in the lung and pleura of chrysotile in combination with fine particles compared to amosite asbestos following short-term inhalation exposure: interim results — D.M. Bernstein, R.A. Rogers, et al. (2010)
• Final results from a 90-day quantitative inhalation toxicology study evaluating the dose-response and fate in the lung and pleura of chrysotile-containing brake dust compared to TiO2, chrysotile, crocidolite or amosite asbestos: Histopathological examination, confocal microscopy and collagen quantification of the lung and pleural cavity — D.M. Bernstein, B. Toth, et al. (2021)
• Evaluation of the exposure, dose-response and fate in the lung and pleura of chrysotile-containing brake dust compared to TiO2, chrysotile, crocidolite or amosite asbestos in a 90-day quantitative inhalation toxicology study - Interim results Part 1: Experimental design, aerosol exposure, lung burdens and BAL — D.M. Bernstein, B. Toth, et al. (2020)

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