Rhinitis patients with sputum eosinophilia show decreased lung function in the absence of airway hyperresponsiveness

Sputum eosinophilia is observed frequently in patients with rhinitis. Sputum eosinophilia in patients with non-asthmatic allergic rhinitis has been suggested to be related to nonspecific airway hyperresponsiveness (AHR). However, the clinical significance of sputum eosinophilia in patients with non-asthmatic rhinitis without AHR has not been determined. We conducted a retrospective study examining the influence of sputum eosinophilia in patients with non-asthmatic rhinitis without AHR on pulmonary function and expression of fibrosis-related mediators.

Eighty-nine patients with moderate-to-severe perennial rhinitis without AHR were included. All underwent lung function tests (forced expiratory volume in 1 second [FEV1] and forced vital capacity [FVC]), skin tests to inhalant allergens, methacholine bronchial challenge tests, and hypertonic saline-induced sputum to determine eosinophil counts. Sputum mRNA levels for transforming growth factor-β (TGF-β), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinase-1 (TIMP-1) were also examined. Patients were divided into two groups according to the presence of sputum eosinophilia (≥3%, eosinophilia-positive [EP] and <3%, eosinophilia-negative [EN] groups).

FEV1 was significantly lower (P=0.04) and FEV1/FVC tended to be lower (P=0.1) in the EP group than in the EN group. In sputum analyses, the MMP-9 mRNA level (P=0.005) and the ratio of MMP-9 to TIMP-1 expression (P=0.01) were significantly higher in the EP group than in the EN group. There was no significant difference in TGF-β mRNA expression between the two groups.

Sputum eosinophilia in patients with moderate-to-severe perennial rhinitis without AHR influenced FEV1 and the expression pattern of fibrosis-related mediators.