Grain dust induces IL-8 production from bronchial epithelial cells: the effect of dexamethasone on IL-8 production.
BACKGROUND
Recent publications have suggested an active participation of neutrophils to induce bronchoconstriction after inhalation of grain dust (GD).


OBJECTIVE
To further understand the role of neutrophils in the pathogenesis of GD-induced asthma, this investigation was designed to determine whether human bronchial epithelial cells could produce IL-8 production and to observe the effect of dexamethasone on IL-8 production.


METHODS
We cultured Beas-2B, a bronchial epithelial cell line. To observe GD-induced responses, four concentrations (1 to 200 microg/mL) of GD were incubated for 24 hours and compared with those without incubation of GD. To evaluate the effect of pro-inflammatory cytokines on IL-8 production, epithelial cells were incubated with peripheral blood mononuclear cell (PBMC) culture supernatant, which was derived from the culture of PBMC from a GD-induced asthmatic subject under the exposure to 10 microg/mL of GD, and compared with those cultured without addition of PBMC supernatant. The level of released IL-8 in the supernatant was measured by enzyme-linked immunosorbent assay. To evaluate the effect of dexamethasone on IL-8 production, four concentrations (5 to 5000 ng/mL) of dexamethasone were pre-incubated for 24 hours and the same experiments were repeated.


RESULTS
There was significant production of IL-8 from bronchial epithelial cells with additions of GD in a dose-dependent manner (P < .05), which was significantly augmented with additions of PBMC supernatant (P < .05) at each concentration. Compared with the untreated sample, pretreatment of dexamethasone could induced a remarkable inhibitions (15% to 55%) of IL-8 production from bronchial epithelial cells in a dose-dependent manner.


CONCLUSIONS
These results suggest that IL-8 production from bronchial epithelial cells may contribute to neutrophil recruitment occurring in GD-induced airway inflammation. The downregulation of IL-8 production by dexamethasone from bronchial epithelial cells may contribute to the efficacy of this compound in reducing cellular infiltration and ultimately to its anti-inflammatory property.
Park
H S
HS
Department of Allergy and Clinical Immunology, Ajou University School of Medicine, Suwon, Korea.
Suh
J H
JH
Kim
H Y
HY
Kwon
O J
OJ
Choi
D C
DC
D001980:Bronchi / Q000187:drug effects* / Q000276:immunology* / Q000378:metabolism; D002474:Cell-Free System / Q000276:immunology; D003907:Dexamethasone / Q000494:pharmacology*; D004391:Dust / Q000009:adverse effects; D002523:Edible Grain / Q000276:immunology*; D004847:Epithelial Cells / Q000187:drug effects* / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000276:immunology
D004391:Dust; D016209:Interleukin-8; D003907:Dexamethasone