Single and repeated zinc-oxide exposure in asthma: effect on airway inflammation.
Reintjes K; Witten A; Balmes J; Blanc P; Solomon C
Am J Respir Crit Care Med 2003 Apr; 167(7):A505
Single and repeated exposure to zinc-oxide (ZnO) results in an increase in inflammatory cells and cytokines in healthy individuals. The chronic airway inflammation in asthma could increase ZnO-induced inflammation, however this is unknown. This experiment was designed to test the hypothesis that exposure to ZnO on two consecutive days would decrease both the cellular and cytokine responses, compared to one exposure, in individuals with asthma. Utilizing a repeated measure, counter-balanced, single-blind design, 10 subjects with asthma (8 females; age range 22-47 yr; methacholine PC20 < 5 mg ml) were exposed for 30 min, at rest, to: 1) filtered-air (FA); 2) ZnO; one exposure (ZnO-1: 10 mg m3); 3) ZnO; two exposures (ZnO-2: 10 mg m3). Sputum induction (3% saline, t = 20 min) was performed 65 h pre- and 6 h post-exposure. Comparisons were made within (pre- vs post-exposure), and between-conditions (post- minus pre-exposure delta). Within ZnO-1, there was a significant (P<0.05) increase in the neutrophil percent (median; 25-75% range: 67.3; 58.9-74.6 vs 38.1; 26.7-68.5%), the delta of which, compared to FA, was increased (18.6; 5.7-26.7 vs -1.8; -7.7-7.7%). In ZnO-2, compared to FA, there was a significant increase in the total leukocyte concentration (175; 125-240 vs 89; 61-133 x l04 cells ml), andTNFa (5.9; 3.6-25.0 vs 0.; 0.01.4 pg ml). There were no significant differences in any variables between ZnO-1 and ZnO-2. These results indicate that in individuals with asthma, both single and repeated exposure to ZnO causes an increase in indices of inflammation, but that the specific cell and protein changes could be different as a function of the exposure format.
Zinc-compounds; Exposure-levels; Airway-obstruction; Airway-resistance; Cellular-reactions; Air-filters; Respiratory-system-disorders; Pulmonary-system-disorders; Bronchial-asthma
Abstract; Conference/Symposia Proceedings
Disease and Injury; Asthma and Chronic Obstructive Pulmonary Disease
American Journal of Respiratory and Critical Care Medicine, 2003 International Conference, The American Thoracic Society, Seattle, WA, May 16-21, 2003
Center for Occupational and Environmental Health, University of California, Berkeley, California