Background Allergic rhinitis (AR) and asthma are frequently associated and characterized by a Th2-dependent inflammation. Nasal and bronchial obstruction may be objectively measured.
Objective The aim of this study was to evaluate the relationships among upper and lower airway function and nasal inflammation in subjects with seasonal allergic rhinitis (SAR) and asthma.
Methods Twenty out-patients (12 males and eight females, mean age: 23.4+3.6 years) with SAR and asthma were evaluated during the pollen season. All of them showed a moderate–severe grade of nasal obstruction. Total symptom score, rhinomanometry, spirometry, nasal lavage, and nasal scraping were obtained in all subjects. Eosinophils were counted by conventional staining; IL-4 and IFN-γ were measured by immunoassay on fluids recovered from nasal lavage.
Results Functional parameters, i.e. nasal airflow and forced expiratory volume in 1 s (FEV1), were correlated with nasal eosinophils (R2>0.83, P<0.001). Inflammatory parameters, i.e. eosinophils were correlated with immunological parameters, i.e. IL-4 and IFN-γ levels (R2=0.93, P<0.001). Nasal symptoms were correlated with nasal airflow (ρ=−0.71, P0.01) and eosinophils (ρ=0.72, P<0.01). Nasal airflow was correlated with FEV1 (r=0.89, P<0.0001).
Conclusions This study demonstrates the close connection between Th2 cytokines and eosinophil infiltration in the nose. There is also clear evidence concerning the relationships between eosinophils infiltration and cytokines levels. Nasal eosinophils can be regarded as the most important predictors of upper and lower airway functions. These findings constitute first evidence of a relationship among nasal Th2-related inflammation and nasal and bronchial airflow in patients with SAR and asthma.