Abstract
Purpose: :
Initiation of corneal healing occurs through collective migration of epithelial cells as a monolayer to cover the site of injury. In order for this to occur, adhesion junctions tethering cells together must loosen. We recently reported that disruption of cell membrane localization of an integral adhesion molecule, BVES (blood vessel epicardial substance), leads to reduction in adhesion junction (tight junction and adherens junction) formation, increased RhoA activation, and increased cellular motility. From these observations we hypothesize that the extracellular domain of BVES plays a role in modulating collective cellular migration.
Methods: :
To test our hypothesis an antibody directed against a conserved region contained within the extracellular domain (a.a. 15-37) of BVES was applied to confluent cultured human corneal epithelial cells at various concentrations (0.1 ng/ml, 0.2 ng/ml, 0.5ng/ml, and 1ng/ml) for 24 hrs. Cells were evaluated for changes in subcellular localization and levels of adhesion junction proteins (occludin, ZO-1, E-cadherin, beta-catenin), and RhoA activation. In addition, assays to asses monolayer barrier function (transepithelial electrical resistance, TER) and collective cellular migrate (scratch/wounding assay) were carried out. Antibody targeting an intracellular domain of BVES was used a control.
Results: :
With 1 ng/ml, monolayers of HCE cells peeled away from the culture plates, while remaining adherent at lower concentrations. By immuno-fluorescent localization, neighboring cell membrane dehiscence was observed at all antibody concentrations. However, adhesion junction proteins were not displaced from the cell membrane. Interestingly at sites of cell membrane dehiscence, adhesion junction proteins were observed at adjacent cell membranes in a tram-track pattern. Disruption of cell-cell adhesion was further verified by observed reduction in TER, which indicates disruption of epithelial monolayer barrier. In scratch/wounding assays, we observed more rapid wound closure following treatment with antibodies to the extracellular domain of BVES but not with control antibody treatment.
Conclusions: :
Our findings indicate that blockade of the extracellcellular domain of BVES leads to disruption of cell-cell adhesion and increased collective migration of HCE cells as an epithelial sheet. These results suggest antibody blockade of extracellular domain of BVES may accelerate epithelial wound healing. Currently, animal studies are in progress to evaluate the therapeutic potential of this antibody.
Keywords: cell adhesions/cell junctions • cell-cell communication • cornea: epithelium