An assessment of asbestos body formation in extrapulmonary sites: liver and spleen

Our plain-English summary of An assessment of asbestos body formation in extrapulmonary sites: liver and spleen, by M.G. Williams, R.F. Dodson, E.W. Dickson, et al (Toxicology and Industrial Health, 2001).

The study

• Authors: M.G. Williams, R.F. Dodson, E.W. Dickson, A.E. Fraire
• Journal: Toxicology and Industrial Health
• Published: 2001;17(1):1-6
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Study Objectives: Asbestos bodies (ABs) form as asbestos fibers become coated by a cellular iron- and protein-rich matrix. ABs have been reported in lymph nodes and a few extrapulmonary sites, but no data exist as to their formation outside of the lung. It is not clear whether the AB found in these extrapulmonary areas have been transported as mature structures from the lung or formed at the extrapulmonary site. This study was designed to determine if ABs are produced in extrapulmonary sites. The guinea pig efficiently forms ferruginous bodies in the lung and so it was chosen as a model to test the coating efficiency of amosite asbestos fibers in lung, liver and spleen.

Design: Sized amosite asbestos (5 mg) was administered either endotracheally into lung (n = 2) or directly into liver (n = 4) and spleen (n = 4) of healthy 10-week-old male guinea pigs. The lung, liver and splenic tissues were removed at 40 and 180 days post inoculation and were examined histologically for the presence of AB via light microscopy. Uncoated fibers isolated from the tissues were characterized by electron microscopy. The coating efficiency was calculated as a ratio of uncoated/coated fibers per organ.

Results: The coating efficiency ratios of fibers that were collected at 40 days post-injection from the individual sites were: lung - 350:1, liver - 4200:1, and spleen - 220,000:1. At 6 months post-injection the ratios for the individual sites consisted of: lung - 176:1, liver - 11,000:1, and spleen - 1000:1.

Conclusion: This study indicates that AB can be formed in extrapulmonary sites and that the coating efficiency in the lung is much greater than that within the liver or spleen.

In plain English

In this animal experiment, the authors tested whether asbestos bodies (asbestos fibers coated with iron- and protein-rich material) can form outside the lung in guinea pigs. They placed 5 mg of amosite asbestos into the windpipe of two animals and injected it directly into the liver of four and spleen of four. Tissues were removed at 40 and 180 days; sections were examined by light microscopy and fibers isolated from digested tissue by electron microscopy. Results were expressed as uncoated fibers per coated fiber, so a larger number means less coating. At 40 days these ratios averaged 350:1 in lung, 4200:1 in liver and 220,000:1 in spleen. At 6 months they were 176:1, 11,000:1 and 1000:1. In liver and spleen, fibers were seen only along the needle tracks, and only a few had a mature coat. One 6-month liver sample had no asbestos bodies detected. The authors concluded that asbestos bodies can form outside the lung, though less efficiently than in it. They noted random sampling, variation between animals, and lung fibers trapped in airways or cleared as limitations.

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: amosite asbestos placed into the lung (through the windpipe) or injected directly into the liver or spleen of guinea pigs. Tissues removed at 40 and 180 days were examined in sections by light microscopy. Fibers isolated from digested tissue were examined by electron microscopy.
• Who was studied: Ten healthy male guinea pigs. Two were given amosite into the lung, one examined at each time point. Four were injected in the liver and four in the spleen, two animals per organ per time point. The summary paragraph gives their age as 10 weeks; the methods give 10 to 12 weeks. The study was done under the animal care committee of the University of Massachusetts Medical Center.
• Exposure: A single dose of 5 mg of sized amosite asbestos in 0.1 ml of saline at each site. The fibers were a mix of mostly short with some long fibers. The text gives an average length of 5.83 micrometres, an average width of 0.34 micrometres, and 21 per cent longer than 8 micrometres.
• Main results:
  • Ratios of uncoated fibers to asbestos bodies (higher means less coating) averaged 350:1 in lung, 4200:1 in liver and 220,000:1 in spleen at 40 days. At 6 months they averaged 176:1 in lung, 11,000:1 in liver and 1000:1 in spleen.
  • Comparing uncoated fibers with asbestos bodies at each site, the authors found the lung provided a more efficient environment for coating than the liver or spleen.
  • In the liver and spleen, fibers were seen only along the needle tracks. The authors took this to suggest the fibers had remained stationary.
  • Many fibers in the liver and spleen tissue stained for iron, but only a few showed a mature coat.
  • In the table, one of the two 6-month liver samples had no asbestos bodies detected. No result was available for one of the two 40-day liver samples.
  • No cellular atypia was seen in the liver or spleen. The lungs showed no pleural mesothelial hyperplasia or atypia.
• The authors' conclusion: The authors concluded that asbestos bodies can form at sites outside the lung. They also concluded that coating is much more efficient in the lung than in the liver or spleen.
• Limitations the authors state:
  • The authors noted that the model involves random sampling and that coating efficiency varies between individual animals.
  • Some fibers given into the lung were presumably trapped in the larger airways or cleared before sampling.
  • Fiber and asbestos body counts could not be expressed per tissue weight, because the fibers were concentrated along the needle tracks. The ratios apply only to the sampled sites.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Body Formation, Asbestos Bodies, Ferruginous Bodies, Amosite.

Related studies

• Asbestos fibers in human pulmonary and extrapulmonary tissues — J. Huang, N. Hisanaga, et al. (1988)
• The enigmatic asbestos body: its formation and significance in asbestos-related disease — A. Morgan, A. Holmes (1985)
• Ferritin adsorption on amosite fibers: possible implications in the formation and toxicity of asbestos bodies — B. Fubini, F. Barceló, et al. (1997)
• Beyond foreign-body-induced carcinogenesis: impact of reactive oxygen species derived from inflammatory cells in tumorigenic conversion and tumor progression — F. Okada (2007)
• Transport of inhaled dust to extrapulmonary sites — P.F. Holt (1981)
• Antibody producing cells in the spleens of mice treated with pathogenic mineral dust — S. Szymaniec, D.M. Brown, et al. (1989)

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