Acorus gramineus Solander Preserves Corneal Epithelial Barrier Integrity against PM 2.5 -Induced EMT-Like Remodeling via Suppression of TGF-β/Smad Signaling

Objectives: To evaluate the effects of particulate matter ≤ 2.5 μm (PM 2.5 ) 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 PM 2.5 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: PM 2.5 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: PM 2.5 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 pollutioninduced ocular surface damage.