Professor and Chief, Division of Allergy and Immunology Nationwide Children's Hospital - The Ohio State University Columbus, Ohio, United States
Disclosure(s):
Mitchell Grayson, MD: No relevant disclosure to display
Introduction/Rationale: Respiratory viruses cause significant morbidity and mortality in very young and old. Mechanism of mortality to respiratory viruses are unknown. We have studied Neuregulin-1 (NRG1), a ligand for ERBb receptor tyrosine kinases (ERBb2 -4) and found pre-treatment with NRG1 provides ~75% survival for mice infected with normally lethal doses of influenza A or Sendai virus (a rodent para-influenza virus). Administering NRG1 to human bronchial epithelial cells (hBEC) increased epithelial proliferation and repair following infection with RSV. Epithelial barrier function closely links to epithelial polarity; polarized epithelial cells have an apico-basal axis maintained through 3 polarity complexes: PAR (Par3/Par6/aPKC) and CRB (Crumbs/Pals/Patj), apically, and SCRIB (Scrib/Dlg1/Lgl), basolaterally. Reactive oxygen species (ROS) play a role in airway epithelium permeability also affecting polarity. The current study determined the effect of NRG1 on polarity when given prophylactically before RSV infection of hBEC.
Methods: hBEC grown in transwell were pretreated on the basal side for 5 days with human NRG1 (100 ng) before RSV-gfp (4000 pfu) was added to the apical side. Anti-ERBb2 (10mcg) and anti-ERBb3 (0.1 mcg) antibodies were added for 5 days to the basal side. Immunohistochemistry was performed on paraffin sections for polarity markers (CRB3 and DLG1) d5 post infection. In addition, hBEC were treated for 30 mins at 37oC in CO2 incubator with MitoSOX superoxide indicators to detect mitochondrial superoxide production in live cells.
Results: NRG1 prevented disruption of CRB3 localization by RSV, an effect blocked by anti-ERBb3. Blocking ERBb2 reduced epithelial proliferation (something ERBb3 antagonism did not do), but did not affect localization of polarity proteins. NRG1 treatment reduced mitoROS in RSV infected cells.
Conclusion: NRG1 prevents disruption of airway epithelium apico-basal polarity and reduces excessive ROS thus stabilizing hBEC during infection.
