Effects of 0.2 ppm ozone on biomarkers of inflammation in bronchoalveolar lavage fluid and bronchial mucosa of healthy subjects

Abstract

Several studies evaluating the effects of ozone on healthy as well as asthmatic subjects have shown that short-term exposure to 0.08-0.40 parts per million (ppm) ozone impairs lung function and induces an acute inflammatory response [1][2][3]. These studies have reported an influx of polymorphonuclear neutrophils (PMNs) and secretion of interleukins (IL)-6 and 8, granulocyte macrophage colony stimulating factor (GM-CSF), total protein, albumin, fibronectin and complement C3a [1][2][3].Endothelial adhesion molecules are considered to play a key role in leukocyte recruitment in an inflammatory response. The first step in that recruitment process involves the upregulation of P-and E-selectins (CD62 P and E), which mediate the early adhesion and "rolling" of leukocytes on the vessel wall [4]. Depending on the stimulus, there then occurs an upregulation of a second set of adhesion molecules belonging to the immunoglobulin superfamily including intercellular adhesion molecule-1 (ICAM-1, CD54) and vascular cell adhesion molecule-1 (VCAM-1, CD106) on the vessel wall, which interact with their counterligands on the leukocyte surface: leukocyte functional antigen (LFA-1, CD11a/CD18) and very late antigen (VLA-4, CD49d/CD29), respectively. This leads to firm adhesion, leukocyte priming, and transmigration of the leukocyte from the intravascular compartment to the extravascular space [4].It has been shown previously that short-term exposure to 0.12 ppm ozone induces rapid upregulation of P-selectin in the microvascular endothelium of healthy bronchial submucosa and that this represents one of the earliest In order to investigate the mechanisms contributing to neutrophil recruitment and to examine the role of T-cells in the acute inflammatory response, we exposed 12 healthy humans to 0.2 parts per million (ppm) of ozone and filtered air on two separate occasions for 2 h with intermittent periods of rest and exercise (minute ventilation=30 L·min -1 ). Fibreoptic bronchoscopy was performed 6 h after the end of exposures. Total protein, tryptase, histamine, myeloperoxidase, interleukin (IL)-8 and growth-related oncogene-α (Gro-α) were measured and total and differential cell counts were performed in bronchoalveolar lavage (BAL) fluid. Flow cytometry was performed on BAL cells to study total T-cells, T-cell receptors (αβ and γδ), T-cell subsets (CD4+ and CD8+ cells) and activated T-cell subsets (CD25+). Using immunohistochemistry, neutrophils, mast cells, total T-cell numbers, T-cell subsets, CD25+ T-cells and leukocyte endothelial adhesion molecules including P-selectin, E-selectin, intercellular adhesion molecule (ICAM)-1 and vascular adhesion molecule (VCAM)-1 were quantified in the bronchial biopsies.Paired samples were available from nine subjects. Following ozone exposure there was a threefold increase in the proportion of polymorphonuclear neutrophils (PMNs) (p=0.07) and epithelial cells (p=0.05) in BAL fluid. This was accompanied by increased concentrations of IL-8 (p=0.01), Gro-α (p=0.05) and total protein (p=0.058). A ...

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Vγ1+ T Cells and Tumor Necrosis Factor-Alpha in Ozone-Induced Airway Hyperresponsiveness

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