Characterization of the bronchoalveolar cellular response in experimental asbestosis. Different reactions depending on the fibrogenic potential

Our plain-English summary of Characterization of the bronchoalveolar cellular response in experimental asbestosis. Different reactions depending on the fibrogenic potential, by I. Lemaire (The American Review of Respiratory Disease, 1985).

The study

• Author: I. Lemaire
• Journal: The American Review of Respiratory Disease
• Published: 1985;131(1):144-9
• Cited by: 46 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Analysis of bronchoalveolar cell types and structure was performed during the development of asbestos-induced lung injury in the rat. Animals received single intratracheal injections of one of the following: saline (control), UICC chrysotile B asbestos (5 mg), or very short 4T30 chrysotile fibers (5 mg). Bronchoalveolar lavage (BAL) was performed at various intervals after instillation. Analysis of BAL fluid showed significant increase in inflammatory cells in response to asbestos, which persisted longer in animals treated with chrysotile B. Presence of numerous mitotic figures in BAL fluid of treated animals suggests that macrophage replication may contribute in part to this response. Differential cellular analysis indicated that after injection of long chrysotile fibers, which causes fibrotic lesions within 7 days, polymorphonuclear leukocytes (PMN) appear as early as Day 1 in significant concentration (40%) in the bronchoalveolar compartment and persist through Day 7 after treatment. From Day 7 to Day 21, multinucleated cells (MGC) were found in lavage fluid (5 to 8%). Most of these cells were binucleated, and none had more than 3 nuclei. By contrast, exposure to very short chrysotile fibers caused only a very transient influx of PMN on Day 1. By Day 7, there was a significant increase in MGC, which persisted through Day 21, at which time no fibrosis was apparent. Although most of these cells were binucleated, many cells had 3 or more nuclei. The giant cells were predominantly of the foreign body type, with MGC of the Langhans type also present.(ABSTRACT TRUNCATED AT 250 WORDS)

In plain English

This was an animal experiment in male Wistar rats. Each rat received a single injection into the windpipe of saline (control), 5 mg of UICC chrysotile B asbestos, or 5 mg of very short 4T30 chrysotile fibers. Lung washings (bronchoalveolar lavage) were taken at intervals and the cells were counted. Chrysotile B produced fibrotic lesions around the small airways. The very short fibers produced lesions confined to the air sacs, and no fibrosis was found 60 days after exposure. Both samples raised lavage cell counts, but the rise lasted longer after chrysotile B. Neutrophils, a type of white blood cell, still made up 44% of cells on Day 7 after chrysotile B but rose only briefly after the short fibers. Cells with several nuclei peaked on Day 14 at 7% of cells after chrysotile B and 11% after the short fibers, against 1% in controls. Cells with 3 or more nuclei were seen mainly after the short fibers. The author concluded that lung cell populations differed depending on the type of lung injury the asbestos caused.

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 (rats given a single intratracheal injection, followed by bronchoalveolar lavage at intervals)
• Who was studied: Male Wistar rats weighing 250 to 300 g from Charles River Canada, studied at the Université de Sherbrooke, Quebec; the number of animals is reported inconsistently (groups of 6, 15 killed per interval, and 5 per data point in the figures)
• Exposure: Single intratracheal injection of saline (control), UICC chrysotile B asbestos (5 mg), or very short 4T30 chrysotile fibers (5 mg)
• Main results:
  • Rats given UICC chrysotile B developed fibrotic lesions consisting of focal fibroblastic proliferation in tissue around the small airways
  • Rats given very short 4T30 fibers had lesions confined to the alveolar structures, and no fibrosis was found 60 days after exposure
  • On Day 1, total lavage cells rose significantly to 12.5 x 10^6 in the very short 4T30 group and 9 x 10^6 in the chrysotile B group, compared with an average of 5.9 x 10^6 in saline controls
  • Cell counts returned to control values by Day 21 in the 4T30 group and by Day 60 in the chrysotile B group, so the increase was more persistent with the long chrysotile fibers
  • In the chrysotile B group, neutrophils (PMN) made up 44% of total cells on Day 7 and returned to normal by Day 14
  • The neutrophil increase lasted longer in rats with fibrotic lesions and was only very transient in the animals without fibrosis (very short fibers)
  • On Day 14, macrophage numbers rose from 5.9 x 10^6 in controls to 15.5 x 10^6 in the chrysotile B group and 11.2 x 10^6 in the 4T30 group
  • Mitotic figures (dividing cells) were 3 to 5 times more frequent in the lavage fluid of asbestos-exposed rats than in controls, which the author suggested may reflect local macrophage replication
  • Multinucleated cells peaked on Day 14 at 7% of total cells after UICC chrysotile B and 11% after 4T30 chrysotile, compared with 1% in controls
  • On Day 14, binucleated cells made up 9.6% of total cells in the short 4T30 group and 7.4% in the UICC chrysotile B group, versus 1.7% in controls
  • Giant cells with 3 or more nuclei were found almost exclusively in rats given very short fibers, where they made up 2.5% of total cells
  • The fusion index was significantly higher with very short fibers (14.1) than with chrysotile B (7.9) or in controls (2.4)
  • Most multinucleated cells were of the foreign body type; a few were of the Langhans type
• The authors' conclusion: The author concluded that bronchoalveolar cell populations differ depending on the nature of the lung injury caused by asbestos. Fibrosis was associated with a more sustained rise in neutrophils and macrophages, and with an absence of the giant cells with 3 or more nuclei that were seen in the alveolitis caused by very short fibers.
• Limitations the authors state:
  • The author stated that the role of neutrophils and multinucleated giant cells in these lung lesions remains to be clarified

Topics

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

Medical terms in this study, explained in our Lexicon: Fibrogenic, UICC, Chrysotile, Bronchoalveolar Lavage (BAL), BAL Fluid, Macrophage, Fibrosis.

Related studies

• Biochemical components of bronchoalveolar lavage in early experimental asbestosis of the sheep: phospholipase A2 activity, prostaglandin E2 and proteins — P. Sirois, G. Drapeau, et al. (1983)
• Alveolar macrophage stimulation of lung fibroblast growth in asbestos-induced pulmonary fibrosis — I. Lemaire, H. Beaudoin, et al. (1986)
• Asbestos-induced alveolar injury. Evidence for macrophage-derived PDGF as a mediator of the fibrogenic response — J.C. Bonner, A.R. Brody (1991)
• The effects of chrysotile and crocidolite asbestos on the lower respiratory tract: analysis of bronchoalveolar lavage constituents — E. Kagan, Y. Oghiso, et al. (1983)
• Lymphocyte subpopulations in bronchoalveolar lavage fluid in asbestos workers — A.R. Gellert, M.G. Macey, et al. (1985)
• An assessment of the fibrogenic potential of very short 4T30 chrysotile by intratracheal instillation in rats — I. Lemaire, D. Nadeau, et al. (1985)

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