Background: Although airway inflammation plays a major role in the pathophysiology of asthma, quantitative markers of airway inflammation are limited in clinical practice.
Objective: To determine if levels of noninvasive markers of eosinophil-catalyzed oxidation, lipid peroxidation, and nitric oxide production are associated with asthma.
Methods: Participants were enrolled from academic medical centers participating in the Severe Asthma Research Program. Clinical characteristics, laboratory data, pulmonary function tests, and levels of the following noninvasive markers were obtained: urinary bromotyrosine, a marker of eosinophil-catalyzed oxidation; urinary F(2)-isoprostanes, markers of lipid peroxidation; and exhaled nitric oxide, a marker of airway inflammation
Results: Fifty-seven asthmatic participants and thirty-eight healthy participants were enrolled. Bromotyrosine, F(2)-isoprostanes, and exhaled nitric oxide were each significantly increased in asthmatic participants versus controls (p<0.01). An elevated level (greater than median) of any marker was associated with a significant 3- to 6-fold greater odds of having asthma. Participants with two or more elevated marker levels showed an 18-fold greater odds of having asthma. Relationships were also noted with airflow obstruction and bronchodilator response.
Conclusion: Findings from this pilot study indicate that urinary levels of bromotyrosine and F(2)-isoprostanes, in addition to exhaled nitric oxide levels, are associated with asthma.
Keywords: Asthma; Biomarkers; Inflammation.