title: Human rhinovirus-induced epithelial production of CXCL10 is dependent upon IFN regulatory factor-1.
abstract: Human rhinovirus (HRV) infections are associated with exacerbations of lower-airway diseases. HRV-induced production of proinflammatory chemokines, such as CXCL10, from infected airway epithelial cells may play a role in the pathogenesis of exacerbations. We have previously shown that the MAP/ERK kinase (MEK) pathway selectively down-regulates HRV-16-induced epithelial production of CXCL10 by modulating nuclear translocation and/or binding of IFN regulatory factor (IRF)-1 with the CXCL10 promoter. Using primary human bronchial epithelial cells (HBEs) and the BEAS-2B bronchial epithelial cell line, we have further evaluated the role of IRF-1 in HRV-16-induced epithelial CXCL10 production. We demonstrate that HRV-16 induced the expression of both IRF-1 mRNA and protein in a time-dependent manner. Interestingly, MEK1 pathway inhibition with PD98059 or U0126 significantly enhanced HRV-16-induced IRF-1 mRNA levels in BEAS-2B cells and HBEs, although IRF-1 protein expression was only enhanced in HBEs. Using short interfering RNA (siRNA), we both inhibited HRV-16-induced IRF-1 expression and reduced nuclear translocation and/or binding of IRF-1 to the CXCL10 promoter. Knockdown of IRF-1 also led to a significant reduction in HRV-16-induced CXCL10 production, confirming that IRF-1 is directly involved in HRV-16-induced CXCL10 expression in epithelial cells. Moreover, pronounced IRF-1 knockdown abrogated the enhancement of CXCL10 normally induced by inhibitors of the MEK1 pathway. Phosphatase experiments indicate that IRF-1 binding to the CXCL10 promoter is not dependent upon its phosphorylation state. We conclude that HRV-16-induced CXCL10 production is dependent upon IRF-1, and that the MEK1 pathway-dependent suppression of CXCL10 expression is also mediated via effects on IRF-1.
authors.affiliation: Airway Inflammation Group, Institute of Infection, Immunity and Inflammation, and Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Raza S
authors.initials: RS
authors.lastname: Zaheer
authors.forename: David
authors.initials: D
authors.lastname: Proud
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D002460:Cell Line; D054357:Chemokine CXCL10 / Q000096:biosynthesis*; D004247:DNA / Q000378:metabolism; D004847:Epithelial Cells / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology / Q000821:virology*; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D050856:Interferon Regulatory Factor-1 / Q000235:genetics / Q000378:metabolism*; D008168:Lung / Q000187:drug effects / Q000276:immunology / Q000473:pathology / Q000821:virology; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D010850:Picornaviridae Infections / Q000235:genetics / Q000276:immunology*; D011485:Protein Binding / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D012229:Rhinovirus / Q000187:drug effects / Q000502:physiology*
chemical_list: C114753:CXCL10 protein, human; D054357:Chemokine CXCL10; C494257:IRF1 protein, human; D050856:Interferon Regulatory Factor-1; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D004247:DNA; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D000469:Alkaline Phosphatase