Oxidant tone regulates IL-8 production in epithelium infected with respiratory syncytial virus.
Respiratory syncytial virus (RSV) is an important respiratory pathogen that preferentially infects epithelial cells in the airway, and causes a local inflammatory response. Although it has been previously demonstrated that RSV-infected airway epithelial produce cytokines, including interleukin-8 (IL-8), which contributes to the inflammatory response, the regulation of this effect of RSV is unknown. To further characterize the mechanisms by which RSV infection triggers release of IL-8, we first exposed cultured A549 cells to RSV, and measured IL-8 release via enzyme-linked immunosorbent assays (ELISA), and IL-8 messenger RNA (mRNA) induction via Northern blot analysis. We observed a dose- and time-dependent release of IL-8 in response to RSV. The optimal dose of RSV was 10(4) TCID50/ml, and maximal release of IL-8 was measured at 72 to 96 h after infection. RSV induced a biphasic (early and late) increase in IL-8 mRNA. The early phase was independent of viral infection, whereas the more pronounced late phase required the presence of live virus and infection of the epithelium. Partial (< 50%) cytopathic effects were noted at 48 h and progressed to 75% at 96 h. The monolayer was still intact at 96 h. Inhibitors of nitric oxide, including NG-monomethyl-L-arginine (L-NMMA), NG-nitro-L-arginine methyl ester (L-NAME), and aminoguanidine had no effect on IL-8 release or IL-8 mRNA induction. We did, however, demonstrate a dose-dependent decrease in IL-8 release and IL-8 mRNA induction in RSV-infected epithelial treated with the antioxidants dimethyl sulfoxide (DMSO) or 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). Peak effects were noted at a concentration of 2% DMSO and 50 microM DMPO. The antioxidants did not inhibit viral replication or infection. This data suggest that RSV-induced IL-8 production in airway epithelium is mediated via changes in oxidant tone. The data also suggest a potential therapeutic role for antioxidants in RSV infections.
Mastronarde
J G
JG
Division of Pulmonary, Critical Care and Occupational Medicine, University of Iowa College of Medicine, Iowa City, USA.
Monick
M M
MM
Hunninghake
G W
GW
D000975:Antioxidants / Q000494:pharmacology; D015152:Blotting, Northern; D004848:Epithelium / Q000378:metabolism / Q000821:virology; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007822:Laryngeal Neoplasms / Q000821:virology; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D016877:Oxidants / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D018357:Respiratory Syncytial Virus Infections / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000821:virology; D014779:Virus Replication / Q000187:drug effects / Q000502:physiology
D000975:Antioxidants; D016209:Interleukin-8; D016877:Oxidants; D012333:RNA, Messenger; D009569:Nitric Oxide