Abstract
The airway epithelium is critical in the pathogenesis of chronic inflammatory diseases, such as asthma and chronic obstructive pulmonary disease, and, by expressing numerous inflammatory genes, plays a prominent role in disease exacerbations. Since inflammatory gene expression often involves the transcription factor nuclear factor (NF)-κB, this signaling pathway represents a site for anti-inflammatory intervention. As the airway epithelium is targeted by inhaled therapeutic agents, for example corticosteroids, human A549 pulmonary cells and primary human bronchial epithelial (HBE) cells were selected to evaluate inhibitor of κB kinase (IKK) inhibitors. In A549 cells, interleukin (IL)-1β and tumor necrosis factor (TNF) α increased phosphorylation of IκBα, and this was followed by loss of IκBα, induction of NF-κB DNA binding, and the induction of NF-κB-dependent transcription. These events were repressed by the IKK-selective inhibitors, PS-1145 [N-(6-chloro-9H-β-carbolin-8-ly) nicotinamide] and ML120B [N-(6-chloro-7-methoxy-9H-β-carbolin-8-yl)-2-methyl-nicotinamide]. Inhibition of NF-κB-dependent transcription was concentration-dependent and correlated with loss of intercellular adhesion molecule (ICAM)-1 expression. Similarly, IL-1β- and TNFα-induced expression of IL-6, IL-8, granulocyte macrophage-colony-stimulating factor (GM-CSF), regulated and activation normal T cell expressed and secreted (RANTES), growth-related oncogene α, and monocyte chemotactic protein-1 (MCP-1) was also significantly repressed. Likewise, PS-1145 and ML120B profoundly reduced NF-κB-dependent transcription induced by IL-1β and TNFα in primary HBE cells. Parallel effects on ICAM-1 expression and a significant repression of IL-8 release were observed. In contrast, the corticosteroid, dexamethasone, was without effect on NF-κB-dependent transcription or the expression of ICAM-1. The above data provide strong support for an anti-inflammatory effect of IKK2 inhibitors acting on the pulmonary epithelium and suggest that such compounds may prove beneficial in situations where traditional corticosteroid therapies prove inadequate.
Footnotes
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This study was supported by a grant from Millennium Pharmaceuticals to Imperial College London. R.N. is a Canadian Institutes of Health Research New Investigator and an Alberta Heritage Foundation for Medical Research Scholar.
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.106.118125.
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ABBREVIATIONS: COPD, chronic obstructive pulmonary disease; IL, interleukin; TNF, tumor necrosis factor; RANTES, regulated and activation normal T cell expressed and secreted; MCP, monocyte chemotactic protein; GRO, growth-related oncogene; ICAM, intercellular adhesion molecule; NF, nuclear factor; IKK, IκB kinase; HBE, human bronchial epithelial; PS-1145, N-(6-chloro-9H-β-carbolin-8-ly) nicotinamide; ML120B, N-(6-chloro-7-methoxy-9H-β-carbolin-8-yl)-2-methyl-nicotinamide; DMSO, dimethyl sulfoxide; MOI, multiplicity of infection; EMSA, electrophoretic mobility shift assay; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; ELISA, enzyme-linked immunosorbent assay; GM-CSF, granulocyte macrophage-colony-stimulating factor.
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The online version of this article (available at http://jpet.aspetjournals.org) contains supplemental material.
- Received December 3, 2006.
- Accepted February 20, 2007.
- The American Society for Pharmacology and Experimental Therapeutics
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