Alveolar nitric oxide (CANO) is a potential biomarker of small airway inflammation. We investigated effects on CANO of the addition of coarse and fine particle inhaled corticosteroids to standard therapy in severe asthma.METHODS
Severe asthmatics taking ≥1600 μg day−1 budesonide or equivalent performed a randomized open-label crossover study. Subjects with FEV1 < 80%, gas trapping and CANO≥2 ppb entered a 6 week dose-ramp run-in of fluticasone/salmeterol(FPSM) 250/50 μg twice daily for 3 weeks, then 500/50 μg twice daily for 3 weeks. Patients then received additional HFA-beclomethasone diproprionate (BDP) 200 μg twice daily or FP 250 μg twice daily for 3 weeks in a crossover. Participants then received prednisolone(PRED) 25 mg day−1 for 1 week. Nitric oxide, lung function, mannitol challenge, systemic inflammatory markers and urinary cortisol were measured.RESULTS
Fifteen completed per protocol: mean (SD) age 51 (12) years, FEV1 58 (13)% predicted, residual volume 193 (100)% predicted and mannitolPD10 177 (2.8) μg. There was no significant difference between FPSM and add-on therapy for CANO. FPSM/BDP and FPSM/PRED suppressed broncial flux (JawNO) and FENO compared with FPSM alone, but there was no significant difference between FPSM/BDP and FPSM/FP. ECP, e-selectin and ICAM-1 were suppressed by FPSM/PRED compared with FPSM and FPSM/FP but not FPSM/BDP. Plasma cortisol was significantly suppressed by FPSM/PRED.CONCLUSION
In severe asthma, CANO is insensitive to changes in dose and delivery of inhaled corticosteroids and is not suppressed by systemic corticosteroids. Additional inhaled HFA-BDP reduced FENO and JawNO without adrenal suppression. There was a trend to reduction in FENO and JawNO with additional FP but this did not reach statistical significance. PRED reduced FENO and JawNO with suppression of systemic inflammatory markers and urinary cortisol.