Circadian Changes in the Sputum of Asthmatic Subjects and Healthy Controls

摘要

Background Asthma is exhibiting classical circadian fluctuations of clinical symptoms and airflow measurements, presumably influenced by the underlying airway inflammation and the endogenous cortisol secretion. The aim of our study was to examine the cellular and eosinophilic cationic protein (ECP) contents of sputum, collected and frozen at 2 opposite time points of the day-and-night cycle, and to correlate them to blood cortisol levels. Methods Thirteen subjects with uncontrolled asthma (8 men, aged 25-54 years) and 10 healthy subjects (6 men, aged 25-50 years) volunteered for the study. They were induced with hypertonic saline to produce sputum between 8:00 AM and 9:00 AM and between 8:00 PM and 9:00 PM , when blood was also withdrawn to measure cortisol levels. Results Asthmatic subjects did not display significant morning/evening differences in their sputum total cell counts ([TCCs] median, 2.06 × 103 cells/mL; range 0.50-5.66 cells/mL vs median, 1.29 cells/mL; range, 0.24-9.26 cells/mL, P > 0.1), whereas controls had a well-defined morning peak (median, 0.75 cells/mL; range, 0.31-2.25 cells/mL vs median, 0.33 cells/mL; range, 0.1-0.97 cells/mL, P > 0.001). Asthmatic subjects had significantly higher sputum TCC than controls in the evening (P Conclusions Sputum undergoes circadian changes, which are different in health and in asthma and do not correlate with endogenous cortisol levels.