Respiratory Enterovirus (like Parainfluenza Virus) Can Cause Chronic Lung Disease if Protection by Airway Epithelial STAT1 Is Lost

Epithelial barrier cells are proposed to be critical for host defense, and airway epithelial cell capacity for IFN signal transduction is presumed to protect against respiratory viral infection. However, it has been difficult to fully test these concepts given the absence of tools to analyze IFN signaling specific to airway epithelial cells in vivo. To address these issues, we generated a new line of transgenic mice with Cre-driver genes (Foxj1 and Scgb1a1) for a floxed-Stat1 allele (designated Foxj1-Scgb1a1-Cre-Stat1^f/f mice) to target the master IFN signal regulator STAT1 in airway epithelial cells and tested these mice for control of infection because of mouse parainfluenza (Sendai) virus and human enterovirus D68 (EV-D68). Indeed, both types of infections showed increases in viral titers and severity of acute illness in Foxj1-Scgb1a1-Cre-Stat1^f/f mice and conventional Stat1²/² mice compared with wild-type mice. In concert, the chronic lung disease that develops after Sendai virus infection was also increased in Foxj1-Scgb1a1-Cre-Stat1^f/f and Stat1^–/– mice, marked by airway and adjacent parenchymal immune cell infiltration and mucus production for at least 7 wk postinfection. Unexpectedly, relatively mild EV-D68 infection also progressed to chronic lung disease in Foxj1-Scgb1a1-Cre-Stat1^f/f and Stat1²/² mice but was limited (like viral replication) to airways. The results thereby provide proof-of-concept for a critical role of barrier epithelial cells in protection from acute illness and chronic disease after viral infection and suggest a specific role for airway epithelial cells given the limitation of EV-D68 replication and acute and chronic manifestations of disease primarily to airway tissue.