Nitric oxide inhibits human rhinovirus-induced transcriptional activation of CXCL10 in airway epithelial cells

Background

Human rhinovirus (HRV) infections trigger exacerbations of asthma and chronic obstructive pulmonary disease. Nitric oxide (NO) inhibits HRV replication in human airway epithelial cells and suppresses HRV-induced epithelial production of several cytokines and chemokines.

Objective

We sought to delineate the mechanisms by which NO inhibits HRV-induced epithelial production of CXCL10, a chemoattractant for type 1 T cells and natural killer cells.

Methods

Primary human bronchial epithelial cells or cells of the BEAS-2B human bronchial epithelial cell line were exposed to HRV-16 in the presence or absence of the NO donor 3-(2-hydroxy-2-nitroso-1-propylhydrazino)-1-propanamine (PAPA NONOate). A cGMP analogue and an inhibitor of soluble guanylyl cyclase were used to examine the role of the cyclic guanosine monophosphate (cGMP) pathway in the actions of NO. BEAS-2B cells were transfected with CXCL10 promoter–luciferase constructs and the effects of PAPA NONOate were examined to study mechanisms of transcriptional regulation. Electrophoretic mobility shift assays were also used.

Results

PAPA NONOate inhibited HRV-16–induced increases in CXCL10 mRNA and protein. Inhibition of CXCL10 production occurred through a cGMP-independent pathway. PAPA NONOate inhibited HRV-16–induced CXCL10 transcription by blocking nuclear translocation, binding, or both of both nuclear factor κB and IFN response factors (IRFs) to their respective recognition elements in the CXCL10 promoter.

Conclusions

NO inhibits HRV-16–induced production of CXCL10 by inhibiting viral activation of nuclear factor κB and of IRFs, including IRF-1, through a cGMP-independent pathway. The broad-ranging inhibition of HRV-induced epithelial cytokine and chemokine production by NO suggests a potential therapeutic utility of NO donors in viral exacerbations of asthma and chronic obstructive pulmonary disease.

Key words: Human rhinovirus, asthma, airway epithelial cell, CXCL10, IFN-γ–inducible protein of 10 kd, nitric oxide, IFN response factors, nuclear factor κB

Abbreviations used: AP-1, Activator protein 1, BEGM, Bronchial epithelial cell growth medium, cGMP, Cyclic guanosine monophosphate, COPD, Chronic obstructive pulmonary disease, dsRNA, Double-stranded RNA, EMSA, Electrophoretic mobility shift assay, GAPDH, Glyceraldehyde-3-phosphate dehydrogenase, HBE, Primary human bronchial epithelial cell, HRV, Human rhinovirus, IKKβ, Inhibitory κB kinase β, iNOS, Inducible nitric oxide synthase, IRF, IFN regulatory factor, ISGF, IFN-stimulated gene factor, ISRE, IFN-stimulated response element, NF-κB, Nuclear factor κB, NO, Nitric oxide, ODQ, 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one, PAPA NONOate, 3-(2-Hydroxy-2-nitroso-1-propylhydrazino)-1-propanamine, PMSF, Phenylmethylsulfonyl fluoride, TCID, Tissue culture infective dose