# Establishing a Non-Surgical Mouse Model of Laryngopharyngeal Reflux Disease: Acid-Induced Epithelial Disruption and Protective Role of N-Acetylcysteine

## TL;DR

This study creates a non-surgical mouse model of LPRD and shows that N-acetylcysteine can help protect against acid-induced tissue damage.

## Contribution

A non-surgical, ingestion-based mouse model of LPRD and evidence of NAC's protective effects are presented.

## Key findings

- Chronic acid exposure caused epithelial disruption and activated the ROS–ERK–c-Jun pathway.
- NAC partially restored E-cadherin and reduced MMP-7 and ERK/c-Jun phosphorylation.
- The model showed no systemic toxicity and mimics key features of LPRD.

## Abstract

Laryngopharyngeal reflux disease (LPRD) results from the retrograde flow of gastric contents into the upper aerodigestive tract, causing epithelial injury. Progress in its management has been limited by the lack of objective biomarkers and reproducible in vivo models. This study aimed to establish a chronic, non-surgical mouse model of LPRD and to investigate the protective effect of N-acetylcysteine (NAC). Female C57BL/6 mice were randomly assigned to three groups: control (standard drinking water), study (acidified water, pH 3.0, for 12 weeks), and treatment (acidified water for 12 weeks plus NAC supplementation during the final 4 weeks). Body weight, food intake, and water consumption were monitored weekly. Pharyngeal tissues were analyzed by immunohistochemistry and Western blotting. Chronic acid exposure resulted in loss of membrane-localized E-cadherin, cytoplasmic redistribution, and upregulation of matrix metalloproteinase-7 (MMP-7). These molecular alterations were accompanied by enhanced phosphorylation of ERK and c-Jun, consistent with activation of the ROS–ERK–c-Jun signaling pathway. NAC supplementation was associated with partial restoration of E-cadherin, reduced MMP-7 expression, and attenuation of ERK/c-Jun phosphorylation. No systemic toxicity or weight loss was observed, indicating good tolerability of the model. This non-surgical ingestion-based model faithfully recapitulates key epithelial features of LPRD and provides a feasible platform for mechanistic investigation and exploratory therapeutic studies. NAC may exert protective effects against acid-induced epithelial injury in this model.