title: In vivo investigation of acidified pepsin exposure to porcine vocal fold epithelia.
abstract: OBJECTIVE
  The study objective was to investigate epithelial changes in response to direct, repeated, acidified pepsin exposures in an in vivo porcine model. We hypothesized that 12 acidified pepsin applications to simulate reflux would elicit a vocal fold response characterized by inflammation, epithelial proliferation, and increased intercellular space, as well as changes in the gene expression of epithelial junctional proteins, ion transporter proteins, and proinflammatory cytokines.
  
  
  METHODS
  Prospective, in vivo study.
  
  
  METHODS
  Pigs received acidified pepsin (pH = 4) or saline (sham) applied directly to vocal folds. Larynges were collected following three exposures per week for 4 weeks. Vocal fold tissue morphology, collagen, and elastin were evaluated histologically. Gene expression of E-cadherin, zona occludens-1, cystic fibrosis transmembrane conductance regulator, epithelial sodium channel, interleukin-1β, tumor necrosis factor-α, and interferon-γ were measured. Ultrastructural alterations, epithelial intercellular space diameter, and microridge height were measured using transmission electron microscopy.
  
  
  RESULTS
  There were no significant differences in histology, gene transcripts, epithelial ultrastructure, intercellular space, and microridge height after acidified pepsin exposure.
  
  
  CONCLUSIONS
  Twelve simulated reflux challenges were insufficient to elicit epithelial changes, demonstrating the resistance of healthy vocal folds to direct, repeated acidified pepsin exposures. These data increase our understanding of healthy vocal fold defenses and lay the groundwork for a prospective, uninjured, nonsurgical, laryngopharyngeal reflux model where pigs can be exposed directly to acidified pepsin.
authors.affiliation: Department of Comparative Pathobiology, Purdue University, West Lafayette, Indiana, U.S.A.
authors.forename: Abigail
authors.initials: A
authors.lastname: Durkes
authors.affiliation: Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, Indiana, U.S.A.
authors.forename: M Preeti
authors.initials: MP
authors.lastname: Sivasankar
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004848:Epithelium / Q000187:drug effects* / Q000648:ultrastructure; D005500:Follow-Up Studies; D005765:Gastrointestinal Agents / Q000494:pharmacology; D007820:Laryngeal Mucosa; D057045:Laryngopharyngeal Reflux / Q000378:metabolism / Q000473:pathology*; D046529:Microscopy, Electron, Transmission; D010434:Pepsin A / Q000494:pharmacology*; D011446:Prospective Studies; D013552:Swine; D014827:Vocal Cords / Q000187:drug effects* / Q000648:ultrastructure
chemical_list: D005765:Gastrointestinal Agents; D010434:Pepsin A
keywords: Basic science; airway and voice modeling; larynx; voice/dysphonia