Acorus gramineus Solander Preserves Corneal Epithelial Barrier Integrity against PM2.5-Induced EMT-Like Remodeling via Suppression of TGF-β/Smad Signaling.

OBJECTIVES

To evaluate the effects of particulate matter ≤ 2.5 µm (PM2.5) on corneal epithelial barrier integrity and to examine the protective potential of Acorus gramineus Solander root extract (AGS).

METHODS

Human corneal epithelial cells (hCECs) were cultured as three-dimensional spheroids and exposed to PM2.5 with or without AGS treatment. Barrier function, tight junction (TJ) integrity, epithelial-mesenchymal transition (EMT)-related markers, inflammatory mediators, and transforming growth factor (TGF)-β/Smad signaling were analyzed.

RESULTS

PM2.5 induced structural instability of hCEC spheroids without substantial cytotoxicity, accompanied by decreased transepithelial electrical resistance and disruption of TJ proteins such as zonula occludens (ZO)-1, ZO-3, and occludin. These alterations coincided with EMT-like remodeling, characterized by the upregulation of N-cadherin and vimentin, increased expression of matrix metalloproteinases, and elevated production of inflammatory cytokines. These effects were associated with the TGF-β/Smad signaling pathway activation. AGS restored barrier integrity, suppressed EMT-like remodeling and inflammation, and inhibited TGF-β/Smad pathway activation.

CONCLUSION

PM2.5 impairs corneal epithelial barrier function through EMT-related and inflammatory mechanisms. AGS exerts protective effects by preserving TJ integrity and suppressing TGF-β/Smad signaling, suggesting its therapeutic potential against air pollution-induced ocular surface damage.