Subepithelial corneal fibrosis partially due to epithelial-mesenchymal transition of ocular surface epithelium

PURPOSE To determine whether epithelial-mesenchymal transition is involved in the development of corneal subepithelial fibrosis (pannus). METHODS Frozen samples of pannus tissue removed from human corneas with a diagnosis of total limbal stem cell deficiency were characterized by immunostaining for both epithelial and mesenchymal markers. We selected transformation-related protein 63 (p63) and pancytokeratin as epithelial markers and vimentin and α-smooth muscle actin (α-SMA) as mesenchymal markers. Immunostaining for β-catenin and E-cadherin was performed to determine wingless-Int (Wnt)-pathway activation. RT-PCR analysis was also performed on epithelial tissue obtained from pannus samples after dispase digestion. RESULTS Immunohistochemistry revealed strong nuclear expression of p63 and weak intercellular expression of E-cadherin in epithelial basal cells of pannus tissue. Furthermore, translocation of β-catenin from intercellular junctions to the nucleus and cytoplasm was also observed. Double-positive cells for both p63 and α-SMA were observed in the subepithelial stroma of pannus tissue, which was supported by RT-PCR and cytospin analysis. CONCLUSIONS Epithelial-mesenchymal transition may be partially involved in the development of subepithelial corneal fibrosis due to total limbal stem cell deficiency.