Disruption of the airway epithelial barrier in a murine model of respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is a major cause of hospitalization for infants and young children worldwide. RSV is known to infect epithelial cells and increase the permeability of model airway epithelial monolayers in vitro. We hypothesized that RSV infection also induces airway barrier dysfunction in vivo. C57BL/6 mice were intranasally inoculated with RSV, and on day 4 post-inoculation were examined for viral replication, lung inflammation, and barrier integrity as well as the structure and molecular composition of epithelial junctions. In parallel, primary mouse tracheal epithelial cells (mTEC) were cultured for in vitro studies. RSV-infected mice lost weight and showed significant peribronchial inflammation compared with noninfected controls and UV-inactivated RSV-inoculated animals. RSV infection increased the permeability of the airway epithelial barrier and altered the molecular composition of epithelial tight junctions. The observed RSV-induced barrier disruption was accompanied by decreased expression of several tight-junction proteins and accumulation of cleaved extracellular fragments of E-cadherin in bronchoalveolar lavage and mTEC supernatants. Similarly, in vitro RSV infection of mTEC monolayers resulted in enhanced permeability and disruption of tight-junction structure. Furthermore, incubation of mTEC monolayers with a recombinant fragment of E-cadherin caused tight-junction disassembly. Taken together, these data indicate that RSV infection leads to airway barrier dysfunction in vivo, mediated by either decreased expression or cleavage of junctional proteins. Our observations provide further insights into the pathophysiology of RSV infection and provide a rationale for development of barrier-protecting agents to alleviate the pathogenic effects of RSV infection.