Alterations in Airway Inflammation and Lung Function During Corticosteroid Therapy for Atopic Asthma: Fiberoptic Bronchoscopy
Bronchodilator medication and caffeine-containing drinks were withheld for at least 12 h before each study visit, and subjects always attended the laboratory at 9 am. Compliance with medication and adverse effects were checked and recorded during each visit. One day prior to each fiberoptic bronchoscopy (day 0-1, day 13, and day 55), histamine bronchial provocation challenges were performed according to a standardized technique. A complete dose-response curve for inhaled histamine was recorded using doubling concentrations of histamine dissolved in normal saline solution, starting at 0.03 mg/mL and going up to 16 mg/mL. FEVl was measured 30 s and 90 s after each dose using a Gould 2400 computerized spirometer (Gould Instruments; Cleveland, OH). The test was terminated if the FEV1 decreased by > 20% from the post-saline solution value or if a concentration of 16 mg/mL was reached. PC20 was determined by linear interpolation of the concentration/FEV-L response curve. Patients were allowed neither albuterol nor salmeterol for 12 h and 36 h, respectively, prior to bronchial challenge. Bronchodilator responses were studied 4 h prior to bronchoscopy (on days 0, 14, and 56). FEV1 was measured before and 20 min after the administration ofalbuterol, 200 μg, via the spacer device. The postbronchodilator FEV1 and percentage change from baseline (bronchodilator response) were recorded.
Fiberoptic bronchoscopy was performed on three occasions in each subject: at baseline, after 2 weeks, and after 8 weeks (day 0, day 14, and day 56). Subjects were sedated with IV propofol, and continuous oxygen was administered via nasal cannula. Oxygen saturation, BP, and ECG were continuously monitored throughout the procedure. Using a flexible fiberoptic bronchoscope (Olympus BF10; Olympus; Tokyo, Japan), up to three endobronchial biopsy samples were obtained through the bronchoscope with spike and cup forceps from the second-generation right upper lobe bronchus. Biopsy samples were immediately placed on sterile phosphate-buffered saline solution-moistened gauze, embedded in optimum cutting temperature medium, and snap-frozen in isopentane (precooled in liquid nitrogen). The samples were then stored in liquid nitrogen (for < 1 month) until further analysis.