Original Articles: Mechanisms of Allergy
Effect of ozone and nitrogen dioxide on the release of proinflammatory mediators from bronchial epithelial cells of nonatopic nonasthmatic subjects and atopic asthmatic patients in vitro,☆☆

https://doi.org/10.1067/mai.2001.111141Get rights and content

Abstract

Background: Although studies have suggested that ozone (O3) and nitrogen dioxide (NO2) may play a role in the pathogenesis of asthma, the underlying mechanisms are not clear. Objective: We aimed to investigate the effects of O3 and NO2 on the release of IL-8, GM-CSF, RANTES, and soluble intercellular adhesion molecule 1 (sICAM-1) from human bronchial epithelial cells (HBECs) of nonatopic nonasthmatic subjects (nonasthmatic subjects) and atopic subjects with mild asthma (asthmatic subjects) in vitro. Methods: We cultured HBECs from bronchial biopsy specimens of nonasthmatic and asthmatic subjects; exposed these for 6 hours to air, 10 to 100 ppb O3, or 100 to 400 ppb NO2; and analyzed the release of IL-8, GM-CSF, RANTES, and sICAM-1 after 24 hours’ incubation. Results: There was no significant difference between the constitutive release of IL-8, GM-CSF, and sICAM-1 from HBECs of asthmatic and nonasthmatic subjects. RANTES was detected only in HBECs derived from asthmatic subjects. Exposure of HBECs of asthmatic subjects to both 50 to 100 ppb O3 and 200 to 400 ppb NO2 significantly increased the release of IL-8, GM-CSF, RANTES, and sICAM-1 from these cells after 24 hours of incubation. However, 50 to 100 ppb O3 and 200 to 400 ppb NO2 led to a significant increase in release of only IL-8 and sICAM-1 from HBECs of nonasthmatic subjects after 24 hours’ incubation. A comparison between the pollutant-induced release of mediators demonstrated that 100 ppb O3-induced release of GM-CSF and sICAM-1 was significantly greater in HBECs of asthmatic subjects (medians, 0.59 and 27.4 pg/μg cellular protein, respectively) than in HBECs of nonasthmatic subjects (medians, 0.27 and 14.4 pg/μg cellular protein, respectively; P < .02). Conclusion: These results suggest that O3 and NO2 may modulate airway diseases, such as asthma, by increasing the release of inflammatory mediators from bronchial epithelial cells and that the cells of asthmatic subjects may be more susceptible to the adverse effects of these pollutants. (J Allergy Clin Immunol 2001;107:287-94.)

Section snippets

Nonatopic nonasthmatic subjects and atopic asthmatic patients

Twenty-eight volunteers (12 women and 16 men) with a mean age of 29 years (range, 19-45 years) took part in the study. Of these, 13 were nonatopic nonasthmatic subjects (control subjects), and 15 were subjects with atopic mild asthma; there were no significant differences in the age and sex ratios. Atopy was confirmed by positive skin prick reactions (wheals with a mean diameter of >3 mm with associated flare and itching in the absence of any reaction to the negative control) to house dust mite

Results

The cells reached confluence after 2 to 3 weeks in culture and demonstrated typical polygonal morphology, which is characteristic of epithelial cells. The epithelial nature of the cells was confirmed by positive staining of the cells for cytokeratin. Staining with specific mAbs against contaminating cell types, including fibroblasts, muscle cells, endothelial cells, macrophages, T and B lymphocytes, mast cells, eosinophils, and neutrophils did not show any indication of these cells.

Discussion

In these studies we have confirmed our previous findings that bronchial epithelial cells can be grown as confluent explant cultures from biopsy specimens of well-characterized atopic patients with mild asthma and nonatopic nonasthmatic subjects.16 To our knowledge, these studies are the first of their kind and demonstrate that HBECs of both nonasthmatic and asthmatic subjects constitutively release proinflammatory mediators and that exposure to gaseous pollutants, such as O3 and NO2, lead to a

Acknowledgements

We thank Ms Janice Thomas (Computer Services Department, St. Bartholomew’s Hospital, London, UK) for her advice on the statistical analysis of the data.

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    Supported by the National Asthma Campaign, UK. Dr Hasan Bayram was supported by the University of Dicle, Turkey.

    ☆☆

    Reprint requests: Hasan Bayram, MD, PhD, Department of Respiratory Medicine, School of Medicine, University of Dicle, Diyarbakır, 21280, Turkey.

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