Runqi Lin, University of Manitoba

Runqi Lin - Department of Medical Microbiology and Infectious Diseases, Rady Faculty of Health Sciences, University of Manitoba; Biology of Breathing Group, The Children's Hospital Research Institute of Manitoba. Júlia A. Cerato - Department of Medical Microbiology and Infectious Diseases, Rady Faculty of Health Sciences, University of Manitoba; Biology of Breathing Group, The Children's Hospital Research Institute of Manitoba. Ronaldo S. Alves Jr - Department of Medical Microbiology and Infectious Diseases, Rady Faculty of Health Sciences, University of Manitoba; Department of Biological Sciences, Paulista State University (UNESP), Brazil. Barbara N. Porto - Department of Medical Microbiology and Infectious Diseases, Rady Faculty of Health Sciences, University of Manitoba; Biology of Breathing Group, The Children's Hospital Research Institute of Manitoba.

Damaging & Spreading

Aim: Respiratory syncytial virus (RSV) is the leading cause of infant hospitalization, yet there are no specific antiviral treatments for children. Airway epithelial cell death and sloughing are hallmarks of RSV bronchiolitis. Members of the gasdermin (GSDM) family of pore-forming proteins, GSDMD and GSDME, are terminal executioners of inflammasome signaling and pyroptosis, a form of inflammatory lytic cell death with context-dependent roles during viral infections. While RSV has been reported to induce pyroptosis in macrophages, whether it triggers airway epithelial cell pyroptosis is unknown. This study aims to determine the mechanisms underlying RSV-induced airway epithelial cell pyroptosis. Methodology: Immortalized human bronchial epithelial cells (HBEC3-KT) were infected with RSV-GFP. Infection was visualized using fluorescence microscopy and viral replication was quantified via plaque assay. Cell lysis was assessed by measuring LDH release. GSDMD and GSDME expression and activation were determined via immunoblotting and immunofluorescence. GSDMD activity was inhibited using disulfiram and LDC7559. GSDMD and GSDME expression were silenced by siRNA-mediated knockdown. Results: RSV induced caspase-1-dependent pyroptosis accompanied by GSDMD-activation in HBEC3-KT. GSDMD and GSDME knockdown revealed both proteins contribute to RSV-induced pyroptosis. Pharmacological inhibition of GSDMD reduced cell lysis and RSV infection of HBEC3-KT. Silencing of GSDMD and GSDME reduced viral release from infected HBEC3-KT. Conclusions: These results indicate RSV infection induces active pyroptosis in airway epithelial cells, partially mediated by caspase-1 and GSDMD. Interestingly, both GSDMD and GSDME are involved RSV release from infected epithelial cells. These findings suggest GSDMD is a plausible target for host-directed therapy against RSV infection.