Bronchial diffusing capacity of nitric oxide is increased in patients with allergic rhinitis

Exhaled nitric oxide (NO) measurement at multiple exhalation flow rates allows calculation of flow-independent NO parameters: alveolar NO concentration, bronchial NO flux, bronchial diffusing capacity of NO and bronchial wall NO concentration.

In the present study, we measured the flow-independent NO parameters and inflammatory markers in exhaled breath condensate (EBC) and in serum in 14 patients with seasonal allergic rhinitis (AR) without asthma, and in 14 age- and sex-matched healthy volunteers.

At symptomatic stage before the treatment, patients with AR had higher bronchial wall diffusing capacity of NO than healthy volunteers (p = 0.024), but there were no differences in bronchial wall NO concentration or alveolar NO concentration. Patients with AR had also increased 8-isoprostane levels in the EBC (p = 0.040), and increased serum levels of IgE (p = 0.002) and eosinophil cationic protein (ECP; p = 0.027). Two-week treatment with nasal glucocorticoid mometasone decreased symptom scores and serum ECP levels but had no effect on NO parameters or 8-isoprostane levels in EBC.

Noninvasive markers of airway inflammation showed subclinical lower airway inflammation in patients with AR without asthma, but short-term treatment with nasal glucocorticoids did not affect most of the markers of lower airway inflammation.