Changes in autacoid and neuropeptide contents of lung cells in asbestos-induced pulmonary fibrosis

Our plain-English summary of Changes in autacoid and neuropeptide contents of lung cells in asbestos-induced pulmonary fibrosis, by R. Day, S. Lemaire, D. Nadeau, et al (The American Review of Respiratory Disease, 1987).

The study

• Authors: R. Day, S. Lemaire, D. Nadeau, I. Keith, I. Lemaire
• Journal: The American Review of Respiratory Disease
• Published: 1987;136(4):908-15
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The purpose of this study was to determine if asbestos-induced pulmonary fibrosis in the rat can affect the levels of autacoids and peptides in freshly isolated lung cells. Lung fibrosis was experimentally induced in rats by a single intratracheal instillation of 5 mg UICC Canadian chrysotile B fibers. Isolated lung cells were prepared from normal and from asbestos-exposed rats. These cells were also fractionated on bovine serum albumin (BSA) gradients. The contents of serotonin (5-HT), histamine (HIST), vasoactive intestinal peptide (VIP), and bombesin (BN) were measured in isolated total cell preparations as well as in density-fractionated cell populations from normal and from asbestos-exposed rats. Analysis of total lung cell preparation showed the presence of heterogeneous populations in normal rat lung. After asbestos exposure, there were significant changes in these cell populations as evidenced by significant increases in lymphocyte and mast cell numbers. In addition, increased levels of 5-HT, HIST, and VIP were observed in isolated lung cells obtained from rats exposed to asbestos 1, 3, and 6 months after instillation. BN content was unchanged 3 months after treatment, but was significantly increased at the 6 month-interval, suggesting a different pattern of response for this neuropeptide. Density fractionation of various cell populations further showed selective changes in specific cell fractions of lung after asbestos exposure. At 6 months, increased levels of 5-HT, HIST, and VIP were associated with cell fraction 7, whereas changes in BN content were found in cell fractions 2 and 3. Similarly, there was a significant increase of mast cells in fraction 7 at the 6-month interval.(ABSTRACT TRUNCATED AT 250 WORDS)

In plain English

In this animal experiment, male Wistar rats received a single 5 mg dose of UICC chrysotile B asbestos into the windpipe; control rats received saline. Rats were killed at 1, 3 and 6 months. The authors measured serotonin, histamine, vasoactive intestinal peptide (VIP) and bombesin in isolated lung cells and in seven cell fractions separated by density. At 1 month, asbestos-exposed lungs yielded 225 million cells versus 162 million in controls. Among the isolated cells, the share of lymphocytes rose at all three times, and the share of mast cells rose 2.9-, 2.5- and 1.7-fold at 1, 3 and 6 months. Per million isolated cells, serotonin rose 1.6- to 2-fold, and histamine rose 1.8- and 1.4-fold at 3 and 6 months. The results table marks VIP as significantly higher (about 1.5-fold) at 1 and 3 months, but not at 6 months. Bombesin was higher only at 6 months, in fractions 2 and 3; at 6 months, serotonin and VIP rose in fraction 7. The authors concluded that mast cells appear to be involved in the serotonin, histamine and VIP increases, and that the bombesin changes most likely involve neuroendocrine cells. They noted that other cell types could not be excluded.

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 asbestos or saline into the airway, killed at intervals)
• Who was studied: respiratory pathogen-free adult male Wistar rats weighing 200 to 235 g; at least 5 animals per group at each interval (1, 3 and 6 months)
• Exposure: single intratracheal (transtracheal) instillation of 5 mg UICC chrysotile B asbestos in 0.5 ml saline; controls received 0.5 ml saline
• Main results:
  • Lungs of rats 1 month after asbestos yielded 225 million cells, compared with 162 million for control animals
  • Cell-type results are percentages of the isolated cell preparation; in asbestos-exposed rats, the proportion of lymphocytes was significantly increased at 1, 3 and 6 months
  • In asbestos-exposed rats, the mast cell proportion of isolated lung cells increased 2.9-fold at 1 month, 2.5-fold at 3 months and 1.7-fold at 6 months
  • Mediator contents were measured per million isolated cells; in control rats these were 12.3 to 16.3 pmol of serotonin, 30.7 to 36.1 pmol of histamine, 30.2 to 35.1 fmol of VIP and 39.2 to 58.9 fmol of bombesin per million cells
  • Serotonin (5-HT) content per million lung cells from asbestos-exposed rats increased significantly, 1.6- to 2-fold, at 1, 3 and 6 months
  • Histamine content per million lung cells from asbestos-exposed rats increased 1.8-fold at 3 months and 1.4-fold at 6 months (not determined at 1 month)
  • VIP content per million lung cells in asbestos-exposed rats was marked as significantly higher at 1 month (47.0 versus 30.2 fmol, 150% of control) and at 3 months (50.3 versus 33.3 fmol, 151% of control), but not at 6 months (45.7 versus 35.1 fmol)
  • Bombesin content per million lung cells from asbestos-exposed rats was increased only at a later stage, the 6-month interval (74.5 versus 39.2 femtomoles per million cells in Table 2)
  • At 3 months, the mast cell proportion in asbestos-exposed rats increased in cell fractions 2, 5, 6 and 7, by 2.1, 2.7, 3.9 and 4 times respectively
  • At 6 months, serotonin in asbestos-exposed rats increased 1.7-fold, in fraction 7 only
  • At 6 months, VIP in asbestos-exposed rats increased 1.7-fold in fraction 7
  • At 3 months, no significant change in bombesin was found in any cell fraction from asbestos-exposed rats
  • At 6 months, bombesin in asbestos-exposed rats increased 1.9-fold in cell fraction 2 and 1.8-fold in cell fraction 3
  • The authors interpreted the bombesin changes as most likely occurring in the subset of neuroendocrine cells that contain bombesin
• The authors' conclusion: The authors concluded that their data suggest mast cells are involved in the higher levels of serotonin, histamine and VIP in asbestos-induced fibrosis, and that bombesin disturbances involve other cell populations, most likely neuroendocrine cells
• Limitations the authors state:
  • The results do not exclude a contribution of other cell types to the serotonin, histamine and VIP changes
  • Whether the higher bombesin content is due to increased production, decreased release or more cells is not known

Topics

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

Medical terms in this study, explained in our Lexicon: Pulmonary Fibrosis, Fibrosis, UICC, Chrysotile, Asbestos Exposure.

Related studies

• Asbestos-induced fibrosis in rats: increase in lung mast cells and autacoid contents — I. Keith, R. Day, et al. (1987)
• Cytokine regulation of lung fibroblast proliferation. Pulmonary and systemic changes in asbestos-induced pulmonary fibrosis — I. Lemaire, H. Beaudoin, et al. (1986)
• Pulmonary bombesin in experimentally induced asbestosis in rats — R. Day, I. Lemaire, et al. (1985)
• Immunoregulation of lung fibroblast growth: alteration in asbestos-induced pulmonary fibrosis — I. Lemaire, C. Dubois, et al. (1986)
• Mitochondrial Rac1 GTPase import and electron transfer from cytochrome c are required for pulmonary fibrosis — H.L. Osborn-Heaford, A.J. Ryan, et al. (2012)
• Alveolar macrophage stimulation of lung fibroblast growth in asbestos-induced pulmonary fibrosis — I. Lemaire, H. Beaudoin, et al. (1986)

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