Eosinophilic Inflammation, Remodeling of Lower Airway, Bronchial Responsiveness and Cough Reflex Sensitivity in Non-Asthmatic Subjects with Nasal Allergy

Background: It has been reported that nasal allergy influences the lower airway inflammation and functions. We elucidated whether nasal allergy would contribute to lower airway inflammation and functions. Methods: 266 subjects aged 21–39 years were interviewed with special emphasis on history of asthma and nasal allergies (perennial allergic rhinitis (PAR) and seasonal allergic rhinitis (Japanese cedar pollinosis; PO)). Symptomatic subject was defined when nasal symptoms were present during a 3-week study period. Pulmonary function, provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 s (PC 20 ), capsaicin cough threshold defined as capsaicin concentration eliciting 5 or more coughs (C5) and eosinophil percentage in hypertonic saline-induced sputum were measured. Results: Based on the interview, 232 subjects without asthma were divided into symptomatic (n = 25) and asymptomatic (n = 22) PAR, PO on-season (n = 15) and off-season (n = 36), and non-nasal allergy subjects (control) (n = 134). Sputum eosinophils were significantly greater in symptomatic PAR than another four groups (p < 0.01). FEV 1 /FVC ratio was significantly lower in PAR than control (p < 0.05). Maximum mean expiratory flow was lower in PAR than control (asymptomatic: p < 0.05, symptomatic: p = 0.06). C5 was not different among groups. PAR tended to have a lower PC 20 compared to control (symptomatic: p = 0.078; asymptomatic: p = 0.086). Conclusions: These results suggest that eosinophilic inflammation occurred in symptomatic period of PAR may contribute to development of lower airway remodeling and bronchial hyperresponsiveness. Reversely, PO may not be associated with lower airway eosinophilic inflammation or abnormal bronchial functions. Nasal allergy dose not influence the cough reflex sensitivity.