Surfactant proteins A and D are related to severity of the disease, pathogenic bacteria and comorbidity in patients with chronic rhinosinusitis with and without nasal polyps

Abstract

Background: Surfactant proteins (SP) A and D play a critical role in the innate defence of respiratory mucosa. Although numerous studies have focused on the importance of surfactant in the lower airways, relatively little is known about its role in the upper respiratory system.

Methods: The prospective study was conducted with 61 subjects divided into patients with chronic rhinosinusitis with nasal polyps (CRSwNP), with chronic rhinosinusitis without nasal polyps (CRSsNP) and healthy controls. SP-A and SP-D were detected in nasal lavage fluid (NALF) by ELISA and in nasal mucosa by immunohistochemical staining. Severity of the diseases assessed by preoperative CT score, presence of comorbidity (allergy and bronchial asthma) and bacterial culture from the middle nasal meatus was evaluated.

Results: In nasal mucosa, SPs were localised in ciliated cells of the surface epithelium and serous acini of the submucosal glands. Stronger expression of SPs in submucosal glands was observed in CRSwNP and CRSsNP groups in comparison with controls. In patients with CRSsNP and more severe form of the disease, higher levels of SP-A and SP-D in NALF and stronger immunoreactivity of these proteins in nasal mucosa were detected. Identification of pathogenic bacteria was associated with higher levels of SP-A and SP-D in NALF and nasal mucosa in patients with CRSsNP and control group. Presence of allergy was associated with stronger expression of SP-A in submucosal glands in all CRS patients and with decreased levels of both SPs in NALF in CRSsNP patients.

Conclusions: Surfactant proteins A and D play an important role in innate host defence of upper respiratory tract. Different expression of these proteins in patients with chronic rhinosinusitis indicates possible novel target of therapy in these patients.