title: Rhinovirus infection liberates planktonic bacteria from biofilm and increases chemokine responses in cystic fibrosis airway epithelial cells.
abstract: BACKGROUND
  Intermittent viral exacerbations in patients with cystic fibrosis (CF) with chronic Pseudomonas aeruginosa (PA) infection are associated with increased bacterial load. A few clinical studies suggest that rhinoviruses (RV) are associated with the majority of viral-related exacerbations in CF and require prolonged intravenous antibiotic treatment. These observations imply that acute RV infection may increase lower respiratory symptoms by increasing planktonic bacterial load. However, the underlying mechanisms are not known.
  
  
  METHODS
  Primary CF airway epithelial cells differentiated into mucociliary phenotype were infected with mucoid PA (MPA) followed by RV and examined for bacterial density, biofilm mass, levels of chemokines and hydrogen peroxide (H2O2). The need for dual oxidase 2, a component of NADPH oxidase, in RV-induced generation of H2O2 in CF cells was assessed using gene-specific siRNA.
  
  
  RESULTS
  Superinfection with RV increased chemokine responses in CF mucociliary-differentiated airway epithelial cells with pre-existing MPA infection in the form of biofilm. This was associated with the presence of planktonic bacteria at both the apical and basolateral epithelial cell surfaces. Further, RV-induced generation of H2O2 via dual oxidase 2 in CF cells was sufficient for dispersal of planktonic bacteria from the biofilm. Inhibition of NADPH oxidase reduced bacterial transmigration across mucociliary-differentiated CF cells and the interleukin-8 response in MPA- and RV-infected cells.
  
  
  CONCLUSIONS
  This study shows that acute infection with RV liberates planktonic bacteria from biofilm. Planktonic bacteria, which are more proinflammatory than their biofilm counterparts, stimulate increased chemokine responses in CF airway epithelial cells which, in turn, may contribute to the pathogenesis of CF exacerbations.
authors.affiliation: Department of Pediatrics, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Sangbrita S
authors.initials: SS
authors.lastname: Chattoraj
authors.forename: Shyamala
authors.initials: S
authors.lastname: Ganesan
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Jones
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Helm
authors.forename: Adam T
authors.initials: AT
authors.lastname: Comstock
authors.forename: Rowland
authors.initials: R
authors.lastname: Bright-Thomas
authors.forename: John J
authors.initials: JJ
authors.lastname: LiPuma
authors.forename: Marc B
authors.initials: MB
authors.lastname: Hershenson
authors.forename: Umadevi S
authors.initials: US
authors.lastname: Sajjan
mesh_terms: D018441:Biofilms; D002454:Cell Differentiation; D002478:Cells, Cultured; D018925:Chemokines / Q000096:biosynthesis*; D003550:Cystic Fibrosis / Q000276:immunology / Q000382:microbiology* / Q000821:virology; D004847:Epithelial Cells / Q000276:immunology / Q000382:microbiology / Q000648:ultrastructure / Q000821:virology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D016209:Interleukin-8 / Q000096:biosynthesis; D008855:Microscopy, Electron, Scanning; D010850:Picornaviridae Infections / Q000150:complications*; D011552:Pseudomonas Infections / Q000150:complications; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D020545:Respiratory Mucosa / Q000276:immunology / Q000382:microbiology / Q000648:ultrastructure / Q000821:virology; D012229:Rhinovirus / Q000302:isolation & purification; D015163:Superinfection / Q000150:complications; D019562:Viral Load
chemical_list: D018925:Chemokines; D016209:Interleukin-8; D006861:Hydrogen Peroxide