Uteroglobin-related protein 1 and Clara cell protein in induced sputum of patients with asthma and rhinitis

Rationale: Uteroglobin-related protein 1 (UGRP1) and Clara cell protein (CC16), members of the secretoglobin family, increasingly appear to play a role in airway inflammatory response. Objective: To explore levels of UCRP1 and CC16 in induced sputum of patients with asthma and rhinitis. Methods: Induced-sputum samples of patients with asthma or rhinitis (n = 32 each; atopic asthma, n = 24; atopic rhinitis, n = 20) and from 19 nonsmoking nonatopic control subjects were analyzed for cytology and levels of UGRP1, CC16, and albumin. Measurements and main results: Sputum UCRP1 increased in both asthma and rhinitis, most strikingly so in asthma, in which changes were most significant in atopic individuals. By contrast, sputum CC16 did not change significantly in either condition, although it was positively correlated with UCRP1 in patients and control subjects. Changes in sputum UCRP1 in atopic asthma were not linked to permeability changes reflected by increased albumin levels but correlated positively with sputum macrophages and negatively with eosinophils. The observed differences in UCRP1 and CC16 may be linked to different cell populations being responsible for their secretion; UGRP1 is mainly secreted in larger conducting airways, whereas CC16 is mainly secreted by the nasal and peripheral airways epithelium. Conclusions: The increase in UCRP1 but not of CC16 in asthma and rhinitis suggests that UCRP1 may play a role in these inflammatory diseases.