Nitric oxide inhibits IFN regulatory factor 1 and nuclear factor-kappaB pathways in rhinovirus-infected epithelial cells.
BACKGROUND
Nitric oxide (NO) has previously been shown to inhibit human rhinovirus (HRV) replication in airway epithelial cells and to inhibit rhinovirus-induced epithelial cytokine and chemokine production independently of its effects on viral replication by modulating nuclear translocation and binding of transcription factors.


OBJECTIVE
To define the molecular mechanisms by which NO inhibits HRV-16-induced epithelial production of CXCL10 by affecting nuclear translocation and binding of nuclear factor-kappaB (NF-kappaB) and IFN regulatory factor 1 (IRF-1).


METHODS
Cultured human airway epithelial cells were infected with HRV-16 in the absence or presence of a NO donor, or were preincubated with 2 highly selective inhibitors of inhibitor of kappaB kinase (IKK)beta and then infected with HRV-16. Effects on the NF-kappaB and IRF-1 pathways were examined by using electrophoretic mobility shift assays, Western blotting, and real-time RT-PCR.


RESULTS
Nitric oxide directly inhibited the binding of both recombinant NF-kappaB p50 protein and recombinant IRF-1 to their recognition sequences from the CXCL10 promoter. NO also inhibited phosphorylation of the NF-kappaB inhibitor, IkappaBalpha, in HRV-16-infected cells. In addition, both NO and inhibitors of IKKbeta inhibited viral induction of IRF-1 mRNA and protein.


CONCLUSIONS
Nitric oxide blocks rhinovirus-mediated activation and nuclear translocation of both NF-kappaB and IRF-1. NO also directly inhibits the binding of each of these transcription factors to their respective recognition sites in the CXCL10 promoter. In addition, the ability of HRV-16 to induce epithelial expression of IRF-1 is dependent, at least in part, on viral activation of NF-kappaB.
Koetzler
Rommy
R
Airway Inflammation Group, Institute of Infection, Immunity and Inflammation, University of Calgary, Calgary, Alberta, Canada.
Zaheer
Raza S
RS
Newton
Robert
R
Proud
David
D
D002243:Carbolines / Q000494:pharmacology; D002478:Cells, Cultured; D054357:Chemokine CXCL10 / Q000037:antagonists & inhibitors / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology* / Q000821:virology; D006575:Heterocyclic Compounds, 3-Ring / Q000494:pharmacology; D006801:Humans; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors; D050856:Interferon Regulatory Factor-1 / Q000037:antagonists & inhibitors*; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D009536:Niacinamide / Q000031:analogs & derivatives / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010850:Picornaviridae Infections / Q000276:immunology*; D011725:Pyridines / Q000494:pharmacology; D012229:Rhinovirus
C114753:CXCL10 protein, human; D002243:Carbolines; D054357:Chemokine CXCL10; D006575:Heterocyclic Compounds, 3-Ring; C494257:IRF1 protein, human; D050856:Interferon Regulatory Factor-1; C514957:N-(6-chloro-7-methoxy-9H-beta-carbolin-8-yl)-2-methylnicotinamide; D016328:NF-kappa B; D020030:Nitric Oxide Donors; C456319:PS1145; D011725:Pyridines; D009536:Niacinamide; D009569:Nitric Oxide; D051550:I-kappa B Kinase