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

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. Studies on IL-8 and effects of dexamethasone on hNECs have been hampered by methodological shortcomings. The purpose of the study is to investigate 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 freshly isolated from nasal polyp tissue and healthy inferior turbinate of NP patients (n=12) and from inferior turbinates of healthy donors (n=19) by protease treatment and two negative selection procedures. hNECs were incubated with IL-1β (10ng/ml), TNFα (10ng/ml) or dexamethasone (10, 100 and 1000 Amicrog/ml). After 24h, IL-8 levels were determined in the supernatants by ELISA. Finally, hNECs were incubated with increasing doses of dexamethasone and stained with trypan-blue and annexin-FITC/PI to study apoptosis.

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.