In vivo investigation of acidified pepsin exposure to porcine vocal fold epithelia

Objectives/Hypothesis 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. Study Design 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. Level of Evidence NA Laryngoscope, 126:E12–E17, 2016