Two dimensional protein patterns of bronchoalveolar lavage fluid from non-smokers, smokers, and subjects exposed to asbestos

Our plain-English summary of Two dimensional protein patterns of bronchoalveolar lavage fluid from non-smokers, smokers, and subjects exposed to asbestos, by M. Lindahl, T. Ekström, J. Sörensen, et al (Thorax, 1996).

The study

• Authors: M. Lindahl, T. Ekström, J. Sörensen, C. Tagesson
• Journal: Thorax
• Published: 1996;51(10):1028-35
• Cited by: 40 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Bronchoalveolar lavage (BAL) fluid contains a large number of proteins which comprise a potential resource for studying respiratory effects due to occupational and environmental exposures. A study was undertaken to compare protein patterns of BAL fluid from non-smokers, smokers, and subjects exposed to asbestos.

Methods: BAL fluid samples were analysed with two dimensional gel electrophoresis (2-DE). The separated proteins were detected, quantified, and pattern-matched between different individuals with a computerised imaging system designed for evaluations of 2-DE patterns.

Results: About 200 different protein spots were detected in each sample of BAL fluid. As is the case with blood plasma, the BAL fluid samples contained large amounts of albumin, transferrin, and immunoglobulins. Higher levels of basic proteins were found in smokers than in non-smokers, while subjects exposed to asbestos had increased amounts of several high molecular weight proteins as well as basic proteins. Lower levels of albumin and higher levels of immunoglobulins were found in smokers than in non-smokers, while higher levels of transferrin were found in asbestos exposed subjects than in unexposed subjects. Moreover, in the group exposed to asbestos differences were found between patients with pleuritis and patients with pleural plaque, and one protein spot was found only in two patients with progressive pleural disease.

Conclusion: These results suggest that both smokers and asbestos exposed subjects have significant changes in their airway protein expression compared with non-smokers and unexposed subjects. It is inferred that analysis of protein patterns in the BAL fluid with 2-DE may be used to detect and characterise, at a molecular level, respiratory effects due to occupational and environmental exposures.

In plain English

This Swedish study compared lung-washing fluid (bronchoalveolar lavage) proteins in 12 men previously exposed to asbestos and 18 healthy volunteers, nine of whom smoked. Fiber types, jobs and doses are not given. The patients had pleural plaques or asbestos pleuritis, but the article gives conflicting counts for each. Two dimensional gel electrophoresis showed about 200 protein spots per sample. Among healthy volunteers, smokers had more protein spots detected than non-smokers (230 versus 150) and more basic proteins. Exposed patients' total protein was not increased, but they had more high molecular weight proteins (85 to 186 kDa). Also, 13 spots appeared in five or more of the 12 but in none or one of the 18 controls. Their mean total transferrin stain intensity (integrated optical density) was 32 (standard error 5) versus 16 (standard error 3) in controls. One spot appeared only in the two patients whose pleural disease progressed. The authors noted the subgroups were small and age differences may have affected the findings. They concluded the method may help detect airway protein changes caused by smoking and/or asbestos exposure.

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: Cross-sectional laboratory comparison of lavage fluid proteins between asbestos-exposed patients and healthy volunteers, with a four-year radiographic and lung-function follow-up of 10 patients
• Who was studied: 12 male patients aged 44-66 (five non-smokers, six smokers, one ex-smoker) referred to the pulmonary department at the University of Linköping, Sweden, after previous asbestos exposure. Also 18 healthy volunteers aged 24-42 (11 men and seven women; nine smokers and nine non-smokers). Study dates are not given.
• Exposure: Previous asbestos exposure (fiber type, jobs and doses not stated). Smoking was also compared. The patients had pleural plaques alone or asbestos pleuritis with massive pleural thickening.
• Main results:
  • Total cell count in lavage fluid was significantly higher in both non-smoking and smoking asbestos-exposed subjects than in non-smoking controls (p less than 0.05)
  • Compared with smoking controls, cell counts in asbestos-exposed subjects were not significantly increased
  • Among the healthy controls, more proteins were detected in smokers (230, SE 10) than in non-smokers (150, SE 10), p less than 0.05
  • Smokers had a fourfold increase in basic proteins (pI above 7.5) compared with non-smokers (16% versus 4% of spots in the control group, p less than 0.01)
  • Eight proteins, including albumin, were lower in smokers than in non-smokers (p less than 0.05). Albumin measured 56 (SE 6) in smokers versus 137 (SE 34) in non-smokers, in integrated optical density units.
  • Total protein concentration was not increased in the 12 asbestos-exposed patients compared with the 18 controls
  • Asbestos-exposed subjects had increased amounts of high molecular weight proteins (85 to 186 kDa). Such proteins made up 21% (SE 5) of spots in exposed non-smokers and 16% (SE 2) in exposed smokers, versus 3% (SE 2) in non-smoking controls (p less than 0.01).
  • 13 protein spots appeared in five or more of the 12 asbestos-exposed subjects but in none or only one of the 18 controls (p less than 0.05)
  • Mean total transferrin was 32 (SE 5) in the asbestos-exposed group versus 16 (SE 3) in unexposed controls, in integrated optical density units (p less than 0.01)
  • Both asbestos-exposed smokers and asbestos-exposed non-smokers showed an approximately threefold increase in basic proteins compared with control non-smokers (p less than 0.01)
  • One transferrin isoform was decreased in asbestos-exposed smokers
  • One protein spot was found only in the two patients whose pleural disease progressed over four years
  • One protein spot was increased in patients with pleuritis, and another was increased in patients with pleural plaque
• The authors' conclusion: The authors concluded that two dimensional electrophoresis of lavage fluid may be useful for detecting changes in airway protein expression caused by smoking and/or asbestos exposure
• Limitations the authors state:
  • The pleural disease subgroups contained few individuals, which makes conclusions highly uncertain
  • The asbestos-exposed patients were older than the controls, and this age difference may have affected the findings
  • Some protein changes might reflect recent exposure to organic agents including allergens, although the authors considered this less likely
  • Many of the proteins found were not identified

Topics

Medical terms in this study, explained in our Lexicon: Bronchoalveolar Lavage (BAL), Environmental Exposure, BAL Fluid, Pleural Plaques.

Related studies

• Inorganic particles in bronchoalveolar lavage fluids from nonoccupationally exposed subjects — M. Falchi, L. Biondo, et al. (1996)
• Proteome analysis of bronchoalveolar lavage in individuals from Metsovo, nonoccupationally exposed to asbestos — D.T. Archimandriti, Y.A. Dalavanga, et al. (2009)
• Additional proteins in BAL fluid of Metsovites environmentally exposed to asbestos: more evidence of "protection" against neoplasia? — V. Galani, S. Constantopoulos, et al. (2002)
• Adsorption of proteins by chrysotile and crocidolite: role of molecular weight and charge density — F. Valerio, D. Balducci, et al. (1987)
• 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)
• Asbestos bodies in bronchoalveolar lavage fluid in relation to occupational history — A. Karjalainen, S. Anttila, et al. (1994)

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