Dexamethasone-induced apoptosis of freshly isolated human nasal epithelial cells concomitant with abrogation of IL-8 production

Abstract

Background: Human nasal epithelial cells (hNECs) are the first line of immune defense and are able to produce mediators that recruit, activate and prolong survival of immune cells, among which IL-8 takes an important place. This study investigates the contribution of freshly isolated hNECs to IL-8 production in chronic rhinosinusitis with nasal polyps (CRSwithNP). Secondly, the effects of dexamethasone treatment on hNEC apoptosis and IL-8 production are investigated. Methodology: hNECs were isolated from nasal polyps and healthy inferior turbinate of NP patients and from inferior turbinates of healthy donors by protease treatment and two negative selection procedures. hNECs were incubated with IL-1β, TNF-α or dexamethasone. After 24h, IL-8 levels were determined in the supernatants by ELISA. Finally, hNECs were incubated with increasing doses of dexamethasone and apoptosis was studied. Results: hNECs isolated from nasal turbinates of healthy and NP patients and polyp tissue from NP patients produced similar levels of IL-8. IL-1β induced higher levels of IL-8 production in all types of hNECs without differences between control and NP tissue. Dexamethasone induced apoptosis of hNECs concomitant with abrogation of IL-8 production by hNECs. Conclusions: IL-8 production by human nasal epithelial cells does not differ between NP and healthy tissue under baseline nor stimulatory conditions. Dexamethasone induces apoptosis of hNECs and abrogates IL-8 production.