Pepsin as a causal agent of inflammation during nonacidic reflux

Abstract

Objective: To investigate the contribution of pepsin to inflammation attributed to nonacidic gastric reflux via analysis of inflammatory cytokine and cytokine receptor gene expression in pepsin-treated human hypopharyngeal epithelial cells in vitro. Study Design: Translational research. Setting: This study was performed in an academic research laboratory. Subjects and Methods: Human hypopharyngeal epithelial cells were incubated with or without pepsin (0.1 mg/mL) at pH 7.4, 37°C, overnight. Expression of 84 inflammatory cytokines and cytokine receptors was analyzed via RT2 qPCR array. Results: Expression of a number of inflammatory cytokines and receptors was altered in human hypopharyngeal epithelial cells following overnight treatment with pepsin at neutral pH. Greater than 1.5-fold change in gene expression was detected for CCL20, CCL26, IL8, IL1F10, IL1A, IL5, BCL6, CCR6, and CXCL14 ( P < 0.05). Conclusion: Exposure of hypopharyngeal cells to pepsin in a nonacidic environment induces the expression of several pro-inflammatory cytokines and receptors, including those known to be involved in inflammation of esophageal epithelium in response to reflux and which contribute to the pathophysiology of reflux esophagitis. These data indicate that refluxed pepsin may contribute to laryngeal inflammation associated with nonacidic gastric reflux, including that experienced by patients despite maximal acid suppression therapy.