The surface of the airway epithelium represents a """"""""battleground"""""""" where the host intercepts signals from pathogens and activates innate defenses to combat infection. Wound repair is an essential function of the airway epithelium in response to injury in chronic airway diseases. Rhinovirus (RV) infection is responsible for exacerbations of several of these diseases. We hypothesize that the airway epithelium responds to low concentrations of RV to accelerate wound repair. Further, we predict that high concentrations of RV are toxic to airway epithelial cells and inhibit wound repair. Because the epidermal growth factor receptor (EGFR) is involved in wound repair, we hypothesize that RV accelerates wound repair via a surface signaling pathway activating EGFR. Our long term goals are to investigate viral interactions with the airway epithelium to further our understanding of innate immunity in health and disease. In the short term we will focus on three specific aims. (1) We will study the concentration-dependent effects of RV infection on airway epithelial wound repair and localize viral infection in the wounded epithelium. (2) We will investigate the surface signaling pathway in RV-accelerated wound repair that activates EGFR. (3) Finally, we will examine whether molecules required for RV infection are involved in this surface signaling cascade. In preliminary experiments, RV accelerated wound repair in a scratch wound model, an effect that was not seen with a higher viral concentration. To determine the effects of increasing concentrations of the virus, we will measure the rate of wound repair and markers of cell necrosis. To localize RV infection we will use immunohistochemistry and fluorescent microscopy. In preliminary experiments an inhibitor selective for EGFR tyrosine kinase prevented RV-accelerated wound repair, implicating EGFR activation. We plan to evaluate the surface signaling cascade activating EGFR, using neutralizing antibodies, metalloprotease and oxidase inhibitors, ROS scavengers, and siRNA. In addition, we will measure the release of EGFR ligands and ROS. To evaluate the role of ICAM-1, ceramide and PKC in RV-accelerated wound repair, we will use an antibody to prevent viral attachment, and ceramide and PKC inhibitors. In summary, we suggest that this surface signaling cascade involves: RV 16-> ICAM-1 -> ceramide-PKC-> Duox1-> ROS-"""""""" TACE-"""""""" TGF- a-> EGFR phosphorylation. RV infection has clinical importance because the virus is the predominant cause of the common cold and causes exacerbations of asthma and COPD. Because therapies for RV are not available, investigating viral-epithelial interactions may lead to novel targets for anti-viral therapies and may increase our understanding of airway defenses against injury and infection. ? ? ?
| Koff, Jonathan L; Shao, Matt X G; Ueki, Iris F et al. (2008) Multiple TLRs activate EGFR via a signaling cascade to produce innate immune responses in airway epithelium. Am J Physiol Lung Cell Mol Physiol 294:L1068-75 |
