A Prominent Role for Airway Epithelial NF-κB Activation in Lipopolysaccharide-Induced Airway Inflammation

Abstract

To reveal the causal role of airway epithelial NF-κB activation in evoking airway inflammation, a transgenic mouse was created expressing a mutant version of the inhibitory protein I-κBα. This I-κBα superrepressor (I-κBαSR) acts to repress NF-κB activation exclusively in airway epithelial cells, under the transcriptional control of the rat CC10 promoter (CC10-I-κBαSR). Compared with transgene-negative littermates, intranasal instillation of LPS did not induce nuclear translocation of NF-κB in airway epithelium of CC10-I-κBαSR transgenic mice. Consequently, the influx of neutrophils into the airways and secretion of the NF-κB-regulated neutrophilic chemokine, macrophage-inflammatory protein-2, and the inflammatory cytokine, TNF-α, were markedly reduced in CC10-I-κBαSR mice relative to the transgene-negative mice exposed to LPS. Despite an inability to activate NF-κB in airway epithelium, resident alveolar macrophages from transgene-positive mice were capable of activating NF-κB in a manner indistinguishable from transgene-negative mice. These findings demonstrate that airway epithelial cells play a prominent role in orchestrating the airway inflammatory response to LPS and suggest that NF-κB signaling in these cells is important for modulating innate immune responses to microbial products.