Virus infections are a major cause of
chronic obstructive pulmonary disease (
COPD) exacerbations. Recently,
Toll-like receptor 3 (TLR3) has been demonstrated to react to
double-stranded RNA (dsRNA) and to be involved in the immune responses after
viral infections. In the present study, we examined whether oxidative stress, which is involved in the pathogenesis of
COPD, enhances the responses of TLR3 in airway epithelial cells. The effect of
hydrogen peroxide (H(2)O(2)) on the release of
IL-8 from BEAS-2B cells and primary human bronchial epithelial cells after stimulation with polyinosine-
polycytidylic acid [
poly(I:C)], a synthetic analog of viral dsRNA and a
ligand for TLR3, and the signal transduction were examined. One hundred to 150 muM H(2)O(2) significantly potentiated the release of
IL-8 from the epithelial cells after stimulation with 10 microg/ml
poly(I:C). The H(2)O(2)-augmented
IL-8 release was inhibited by treatment with
N-acetylcysteine. One hundred micromoles of H(2)O(2) enhanced the translocation of nuclear factor (
NF)-kappaB p65, but not that of
interferon regulatory factor-3 (IRF-3), into the nucleus and the
NF-kappaB DNA binding activity after
poly(I:C) stimulation, which effect was inhibited not by the silencing of IRF-3 but by
MG132, a
proteasome inhibitor, or
dexamethasone. One hundred micromoles of H(2)O(2) potentiated the TLR3 expression on the airway epithelial cells treated with
poly(I:C). These data suggest that oxidative stress augments the response of TLR3 in airway epithelial cells via
NF-kappaB and that this effect might be partly mediated by the enhancement of TLR3 expression. Modulation of this pathway may be a therapeutic target for viral-induced exacerbations of
COPD.