Clara cell protein 16 and eosinophil cationic protein production in chronically inflamed sinonasal mucosa

Clara cell protein 16 (CC16) is an anti-inflammatory protein mainly expressed in the epithelial cells in the upper and lower airways. Eosinophil cationic protein (ECP) is an important marker of eosinophil activity in chronic inflammatory sinonasal diseases. The aim of this study was to evaluate mucosal production of CC16 and ECP in patients with perennial allergic rhinitis (PAR), nonallergic and allergic patients with chronic rhinosinusitis with nasal polyposis (CRSwNP), before and after nasal corticosteroid administration.

Twenty patients with PAR, 20 nonallergic CRSwNP patients, 20 allergic CRSwNP patients, and 20 healthy controls were included. Mucosal cytology samples were taken from all participants for quantification of eosinophils. CC16 and ECP levels were measured in the nasal secretion samples. The patients with chronic sinonasal inflammation were treated with fluticasone nasal spray for 14 days. Nasal symptoms assessment, cytological examination, and CC16 and ECP nasal fluid measurements were performed before and after the corticosteroid treatment.

Mean CC16 concentrations in nasal secretions were significantly lower in patients with PAR (p < 0.05) and allergic CRSwNP patients (p < 0.01) compared to controls. Mean ECP levels were significantly higher in patients with PAR, nonallergic CRSwNP patients, and allergic CRSwNP patients compared to the control group (p < 0.001, p < 0.01, p < 0.001, respectively). After nasal corticosteroid therapy, we found a highly significant increase of CC16 (p < 0.001) and reduction of ECP (p < 0.001) in nasal secretions in all 3 groups of patients.

CC16 and ECP measured in nasal secretions could be reliable markers for assessment of the recovery function of sinonasal mucosa during corticosteroid treatment.