The Impact of Pepsin on Human Nasal Epithelial Cells In Vitro: A Potential Mechanism for Extraesophageal Reflux Induced Chronic Rhinosinusitis.

OBJECTIVES

To describe potential mechanisms by which pepsin induces inflammation in refractive chronic rhinosinusitis (CRS). Our hypothesis was that pepsin induces mitochondrial damage and cytokine expression in human nasal epithelial cells (HNEpC) in vitro.

METHODS

Western blot was used to detect pepsin in sinus lavages from patients with CRS and controls. The HNEpC cells were treated with pepsin (pH 7; 0.1 mg/mL) for 1 or 16 hours and routine electron microscopy (EM) and MTT assay were performed. Cytokine ELISA was performed on media collected from HNEpC cells 16 hours following a 1-hour pepsin treatment.

RESULTS

Pepsin was detected in sinus lavages from 4 out of 6 CRS patients and 0 out of 3 controls. The EM showed mitochondrial damage in pepsin-treated HNEpC cells but not in control cells. The MTT assay demonstrated reduced mitochondrial activity in pepsin-treated HNEpC cells compared to controls (P < .001). Pepsin increased IL-1A (P = .003) and IL-6 (P = .04) expression in HNEpC cells.

CONCLUSIONS

Pepsin in sinus lavages from patients with CRS is consistent with previous studies. This study reveals the damaging effect of pepsin on mitochondria in nasal epithelial cells in vitro. Cytokines previously associated with CRS were elevated following pepsin treatment of HNEpC cells in vitro. These results demonstrate mechanisms by which pepsin may potentiate CRS.