Selective IκB Kinase Expression in Airway Epithelium Generates Neutrophilic Lung Inflammation

To determine whether NF-kappaB activation is sufficient to generate lung inflammation in vivo, we selectively expressed a constitutively active form of IkappaB kinase 1 (cIKK1) or IkappaB kinase 2 (cIKK2) in airway epithelium. After intratracheal administration of adenoviral vectors expressing cIKK1 or cIKK2 to transgenic reporter mice that express Photinus luciferase under the control of an NF-kappaB-dependent promoter, we detected significantly increased luciferase activity over time (up to 96 h). Compared with control mice treated with adenoviral vectors expressing beta-galactosidase, lung bioluminescence and tissue luciferase activity were increased in NF-kappaB reporter mice treated with adenovirus (Ad)-cIKK1 or Ad-cIKK2. NF-kappaB activation in lungs of Ad-cIKK1- and Ad-cIKK2-treated mice was confirmed by immunoblots for RelA and EMSA from lung nuclear protein extracts. Mice treated with Ad-cIKK1 or Ad-cIKK2 showed induction of mRNA expression of several chemokines and cytokines in lung tissue. In lung lavage fluid, mice treated with Ad-cIKK1 or Ad-cIKK2 showed elevated concentrations of NF-kappaB-dependent chemokines macrophage-inflammatory protein 2 and KC and increased numbers of neutrophils. Coadministration of adenoviral vectors expressing a transdominant inhibitor of NF-kappaB with Ad-cIKK1 or Ad-cIKK2 resulted in abrogated NF-kappaB activation and other parameters of lung inflammation, demonstrating that the observed inflammatory effects of Ad-cIKK1 and Ad-cIKK2 were dependent on NF-kappaB activation by these kinases. These data show that selective expression of IkappaB kinases in airway epithelium results in NF-kappaB activation, inflammatory mediator production, and neutrophilic lung inflammation. Therapies targeted to NF-kappaB in lung epithelium may be beneficial in treating inflammatory lung diseases.