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Early suppression of NFκB and IL-8 bronchial epithelium after ozone exposure in healthy human subjects
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
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2009 (English)In: Inhalation Toxicology, ISSN 0895-8378, E-ISSN 1091-7691, Vol. 21, no 11, 913-919 p.Article in journal (Refereed) Published
Abstract [en]

Exposure to elevated concentrations of ozone, a common air pollutant, has been associated with numerous adverse health effects. We have previously reported the time-course of ozone-induced airway inflammation, demonstrating an early up-regulation of vascular endothelial adhesion molecules in bronchial mucosa at 1.5 hours, followed by a neutrophilic infiltration 6 hours after exposure to 0.2 ppm ozone. We hypothesized that the neutrophilic infiltration in the bronchial mucosa would reflect an early increase in bronchial epithelial expression of redox-sensitive transcription factors and kinases regulating neutrophil chemoattractant expression. To test this hypothesis, endobronchial biopsies were obtained from healthy human subjects (n = 11) 1.5 hours after 0.2 ppm of ozone and filtered air exposures (lasting for 2 hours) and stained for mitogen-activated protein kinases (MAPKs), transcription factors, and neutrophil chemoattractants. Total epithelial staining was quantified, as well as the extent of nuclear translocation. Contrary to expectation, ozone significantly suppressed total and nuclear expression of nuclear factor κB (NFκB) in bronchial epithelial cells (p = 0.02 and p = 0.003 respectively). Similarly, the total staining for phosphorylated C-jun was suppressed (p = 0.021). Expression of interleukin 8 (IL-8) in the bronchial epithelium was likewise decreased after ozone (p = 0.018), while GRO-α, ENA-78, C-fos, p-p38, p-JNK, and p-ERK stainings were unchanged. These data suggest that the redox-sensitive NFκB and activator protein 1 (AP-1) pathways within the human bronchial epithelium do not seem to be involved in the early inflammatory cell recruitment pathways in healthy subjects exposed to ozone.

Place, publisher, year, edition, pages
Informa Healthcare, 2009. Vol. 21, no 11, 913-919 p.
National Category
Respiratory Medicine and Allergy
URN: urn:nbn:se:umu:diva-2210DOI: 10.1080/08958370802657389OAI: diva2:140103
Available from: 2007-04-02 Created: 2007-04-02 Last updated: 2012-06-29Bibliographically approved
In thesis
1. Ozone and diesel exhaust: airway signaling, inflammation and pollutant interactions
Open this publication in new window or tab >>Ozone and diesel exhaust: airway signaling, inflammation and pollutant interactions
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

It is well established that air pollution has detrimental effects on both human health as well as the environment. Exposure to ozone and particulate matter pollution, is associated with an increase in cardiopulmonary mortality and morbidity. Asthmatics, elderly and children have been indicated as especially sensitive groups. With a global increase in use of vehicles and industry, ambient air pollution represents a crucial health concern as well as a political, economical and environmental dilemma.

Both ozone (O3) and diesel exhaust (DE) trigger oxidative stress and inflammation in the airways, causing symptoms such as wheezing, coughing and reduced lung function. The aim of this thesis was to further examine which pro-inflammatory signaling pathways that are initiated in the airways by ozone, as compared to diesel exhaust. Furthermore, to study the effects of these two ambient air pollutants in a sequential exposure, thus mimicking an urban profile. In order to investigate this in healthy as well as asthmatic subjects, walk-in exposure chambers were utilized and various airway compartments were studied by obtaining induced sputum, endobronchial biopsies, or airway lavage fluids.

In asthmatic subjects, exposure to 0.2 ppm of O3 induced an increase in the cytokines IL 5, GM-CSF and ENA-78 in the bronchial epithelium six hours post-exposure. The healthy subjects, however, displayed no elevations of bronchial epithelial cytokine expression in response to the ozone exposure. The heightened levels of neutrophil chemoattractants and Th2 cytokines in the asthmatic airway epithelium may contribute to symptom exacerbations following air pollution exposure.

When examining an earlier time point post O3 exposure (1½ hours), healthy subjects exhibited a suppression of IL-8 as well as of the transcription factors NFκB and c-jun in the bronchial epithelium, as opposed to after filtered air exposure. This inhibition of early signal transduction in the bronchial epithelium after O3 differs from the response detected after exposure to DE.

Since both O3 and DE are associated with generating airway neutrophilia as well as causing direct oxidative damage, it raises the query of whether daily exposure to these two air pollutants creates a synergistic or additive effect. Induced sputum attained from healthy subjects exposed in sequence to 0.2 ppm of O3 five hours following DE at a PM concentration of 300 µg/m3, demonstrated significantly increased neutrophils, and elevated MPO levels, as compared to the sequential DE and filtered air exposure.

O3 and DE interactions were further investigated by analyses of bronchoalveolar lavage and bronchial wash. It was demonstrated that pre-exposure to DE, as compared to filtered air, enhances the O3-induced airway inflammation, in terms of an increase in neutrophil and macrophage numbers in BW and higher EPX expression in BAL.

In conclusion, this thesis has aspired to expand the knowledge of O3-induced inflammatory pathways in humans, observing a divergence to the previously described DE initiated responses. Moreover, a potentially adverse airway inflammation augmentation has been revealed after exposure to a relevant ambient combination of these air pollutants. This provides a foundation towards an understanding of the cumulative airway effects when exposed to a combination of ambient air pollutants and may have implications regarding future regulations of exposure limits.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2007. 83 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1097
air pollution, ozone, diesel exhaust, airway inflammation, asthma, immunohistochemistry
National Category
Respiratory Medicine and Allergy
Research subject
Lung Medicine
urn:nbn:se:umu:diva-1071 (URN)978-91-7264-266-9 (ISBN)
Public defence
2007-04-21, Sal B, 9 trappor, Tandläkarhuset, Norrlands Universitetssjukhus, Umeå, 09:00 (English)
Available from: 2007-04-02 Created: 2007-04-02 Last updated: 2012-03-01Bibliographically approved

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