Rhinovirus (RV)-Induced Interleukin-8 (IL-8) Production in Respiratory Epithelial Cells is Mediated by H2O2 and is Inhibited by N-Acetyl Cysteine (NAC) † 690

Abstract

A direct correlation has been reported between the severity of common cold symptoms and the concentration of IL-8 in nasal secretions from volunteers with experimental RV colds. The purpose of these studies was to examine the mechanism by which RV infection stimulates IL-8 elaboration. All studies were done in a transformed respiratory epithelial cell line (BEAS-2b). Increased fluorescence staining of carbonyl groups and activation of dichlorofluorescein diacetate was seen in RV-challenged cells suggesting an increase in oxidative stress. Quantitative measurement of H2O2 with a colorimetric assay revealed H2O2 concentrations of 4.74 ± 2.04 μM and.40 ±.49 μM in media from challenged and control cells four hours after virus challenge, respectively (p<0.01). Stimulation of BEAS-2b cells with H2O2 resulted in elaboration of IL-8. Treatment of BEAS-2b cells with NAC significantly inhibited RV-induced IL-8 elaboration. IL-8 concentrations in supernatant media were 183 ± 64 pg/ml and 44 ± 4 six hours after virus challenge in treated (20 mM NAC) and untreated cells, respectively. In spite of the effect of NAC on IL-8 elaboration, RV stimulated increases in H2O2 concentration were not affected by NAC. These results demonstrate that H2O2 is produced in respiratory epithelial cells in response to RV infection and is a potential mediator of RV-induced IL-8 elaboration. NAC inhibits RV-induced IL-8 by a mechanism other than inhibition of H2O2 production.