# Rebamipide Enhances Pathogen Defense and Mitigates Inflammation in a Particulate Matter-Induced Ocular Surface Inflammation Rat Model

## TL;DR

This study shows that rebamipide eye drops reduce inflammation and improve eye health in rats exposed to particulate matter.

## Contribution

The study demonstrates rebamipide's novel efficacy in mitigating PM-induced ocular inflammation compared to hyaluronic acid.

## Key findings

- 2% rebamipide reduced inflammatory markers like MMP-9, IL-1β, and TNF-α in PM-exposed rats.
- Rebamipide enhanced mucin secretion and pathogen clearance via NF-κB and EGFR pathways.
- Rebamipide improved goblet cell density and reduced apoptosis and uncontrolled cell proliferation.

## Abstract

Particulate matter (PM) exposure is known to induce significant ocular surface inflammation, necessitating effective therapeutic interventions. This study compared the efficacy of 2% rebamipide (REB) with 0.1% hyaluronic acid (HA) eye drops in investigating the anti-inflammatory and pathogen-clearance effects in a PM-induced ocular surface inflammation model using Sprague–Dawley (SD) rats. Parameters including clinical signs, histological changes, mucin secretions, inflammatory cytokines, mast cell degranulation, dysregulated cell proliferation, and cellular apoptosis were evaluated. 2% REB alleviated ocular surface inflammation by downregulating the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) inflammatory pathway and upregulating epidermal growth factor receptor (EGFR) signaling, thereby enhancing mucin secretion and promoting pathogen clearance. Histopathological analysis, western blot, and immunohistochemical staining revealed a marked reduction in inflammatory markers including MMP-9, IL-1β, TNF-α, IL-17, and CD-4, decreased mast cell degranulation, increased goblet cell density, and enhanced expression of mucins, including MUC5AC and MUC16, in the 2% REB-treated group compared to the 0.1% HA-treated and PM-exposed groups. Moreover, 2% REB demonstrated decreased apoptosis (TUNEL) and reduced uncontrolled cell proliferation (Ki67), indicating improved cellular integrity. In conclusion, 2% REB is a promising treatment option for PM-induced ocular surface inflammation in a rat model compared with 0.1% HA, offering the benefits of reducing inflammation, clearing pathogens, and protecting overall ocular health.