Inhibition of Enhancer of Zeste Homolog 2 alleviates oxidative stress, inflammation and barrier damage of human corneal epithelial cells

Dry Eye Disease (DED) is a multifactorial condition characterized by tear film instability, ocular surface inflammation, epithelial barrier dysfunction, and oxidative stress (OS). Recent studies have identified Enhancer of Zeste Homolog 2 (EZH2) as an important contributor to ocular surface diseases by promoting inflammation and epithelial dysfunction. Based on these findings, this study investigated the potential therapeutic effects of GSK343, a selective EZH2 inhibitor, in mitigating DED-associated pathological processes using in vitro models. Our findings demonstrated that low concentrations of GSK343 (1, 3 and 5 μM) did not compromise human corneal epithelial (HCE) cell viability and enhanced wound healing, suggesting its role in promoting epithelial regeneration. In H2O2-induced DED model, GSK343 pretreatment significantly restored HCE cell viability following H2O2-induced damage, reduced reactive oxygen species (ROS) levels and upregulated the expression of antioxidant enzymes as HO-1 and MnSOD, indicating a protective effect against OS. Additionally, GSK343 restored tight junction proteins (ZO-1 and occludin), reducing permeability and maintaining barrier integrity. In TNFα-induced DED model, GSK343 restored HCE cell viability and decreased the levels of pro-inflammatory cytokines IL-1β, TNFα, IL-6, and IL-17. Furthermore, GSK343 decreased the number of apoptotic cells and p53 positive cells, highlighting its protective properties. These findings suggest that GSK343 exerts anti-inflammatory, antioxidant, and epithelial-protective effects in DED models, suggesting EZH2 inhibition as a potential therapeutic strategy for DED management.