Background: Airway hypersecretion is a common finding in rhinitis and asthma in which proinflammatory cytokines are upregulated. The effect of inflammation on glandular secretion remains unclear.
Objective: We sought to investigate the effect of proinflammatory cytokines and eosinophil products in in vitro lactoferrin glandular secretion from human nasal mucosa and the role of corticosteroids and IL-10 in modulating this effect.
Methods: Nasal explants from patients undergoing turbinectomies were incubated in a controlled atmosphere (50% N(2), 5% CO(2), and 45% O(2)) at 37 degrees C. Nasal explants were incubated with or without IL-1beta, IL-4, IL-5, IL-8, eotaxin, GM-CSF, TNF-alpha, eosinophil cationic protein (ECP), IL-10, and budesonide in a time-course and dose-response fashion. Lactoferrin concentrations in culture supernatants were measured by means of ELISA.
Results: ECP (up to 30%) caused a dose-related stimulation of lactoferrin secretion. TNF-alpha (20 ng/mL) induced a significant increase of lactoferrin release from 8 hours (27.7% +/- 17.8%, P <.05) to 24 hours (40.8% +/- 17.2%, P <.01) compared with that found in media-treated explants. At 24 hours, TNF-alpha caused a dose-related stimulation of lactoferrin secretion (up to 35%). IL-1beta (65.3% +/- 15.2%, P <.05) and GM-CSF (15.7% +/- 6.7%, P <.05), both at 20 ng/mL, exerted a stimulatory effect only at 24 hours, and IL-4, IL-5, IL-8, and eotaxin had no significant effect. Budesonide caused a dose-related inhibition of lactoferrin secretion induced by IL-1beta (down to -76%) and TNF-alpha (down to -70%), whereas IL-10 had no effect.
Conclusions: ECP and some proinflammatory cytokines (IL-1beta, TNF-alpha, and GM-CSF) may contribute to glandular hypersecretion in the inflamed nose. Corticosteroids may reduce nasal hypersecretion by blocking the direct effect of proinflammatory cytokines on glandular output.