The role of IkappaB kinase 2, but not activation of NF-kappaB, in the release of CXCR3 ligands from IFN-gamma-stimulated human bronchial epithelial cells.
The severity of chronic obstructive pulmonary disease correlates with increased numbers of cytotoxic CD8(+) T lymphocytes in the lung parenchyma. CD8(+) T lymphocytes release IFN-gamma which stimulates airway epithelial cells to produce CXCR3 chemokines leading to further recruitment of CD8(+) T lymphocytes. To evaluate the signaling pathways involved in regulation of CXCR3 ligands, the human bronchial epithelial cell line BEAS-2B was stimulated with IFN-gamma and the release of the CXCR3 ligands was measured by ELISA. The release of CXCL9, CXCL10, and CXCL11 was inhibited by an IkappaB kinase 2 (IKK2) selective inhibitor 2-[(Aminocarbonyl)amino]-5-[4-fluorophenyl]-3-thiophenecarboxamide (TPCA-1) (EC(50) values were 0.50 +/- 0.03, 0.17 +/- 0.06, and 0.45 +/- 0.10 microM, respectively (n = 6)) and an IKK1/2 selective inhibitor 2-amino-6-(2'cyclopropylemethoxy-6'-hydroxy-phenyl)-4-piperidin-3-yl-pyridine-3-carbonitrile (EC(50) values 0.74 +/- 0.40, 0.27 +/- 0.06, and 0.88 +/- 0.29 microM, respectively (n = 6)). The glucocorticosteroid dexamethasone had no effect on CXCR3 ligand release. The release of CXCL10 was most sensitive to inhibition by IKK2 and a role for IKK2 in CXCL10 release was confirmed by overexpression of dominant-negative adenoviral constructs to IKK2 (68.2 +/- 8.3% n = 5), but not of IKK1. Neither phosphorylation of IkappaBalpha, translocation of p65 to the nucleus, or activation of a NF-kappaB-dependent reporter (Ad-NF-kappaB-luc) were detected following stimulation of BEAS-2B cells with IFN-gamma. These data suggest that IKK2 is also involved in the IFN-gamma-stimulated release of the CXCR3 ligands through a novel mechanism that is independent NF-kappaB.
Tudhope
Susan J
SJ
Airway Disease, National Heart and Lung Institute, Imperial College, London, United Kingdom.
Catley
Matthew C
MC
Fenwick
Peter S
PS
Russell
Richard E K
RE
Rumsey
William L
WL
Newton
Robert
R
Barnes
Peter J
PJ
Donnelly
Louise E
LE
D000577:Amides / Q000494:pharmacology; D000818:Animals; D001980:Bronchi / Q000187:drug effects* / Q000378:metabolism*; D002478:Cells, Cultured; D018925:Chemokines / Q000235:genetics / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D007371:Interferon-gamma / Q000494:pharmacology*; D008024:Ligands; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics; D054367:Receptors, CXCR3 / Q000378:metabolism*; D050794:STAT1 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D013876:Thiophenes / Q000494:pharmacology
D000577:Amides; C515187:CXCR3 protein, human; D018925:Chemokines; D008024:Ligands; D016328:NF-kappa B; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D054367:Receptors, CXCR3; D050794:STAT1 Transcription Factor; D013876:Thiophenes; D003907:Dexamethasone; D007371:Interferon-gamma; C499326:2-((aminocarbonyl)amino)-5-(4-fluorophenyl)-3-thiophenecarboxamide; D051550:I-kappa B Kinase