Disruption of zonula occludens-1 localization in the rabbit corneal epithelium by contact lens-induced hypoxia.

PURPOSE Hypoxia impairs the barrier function of the corneal epithelium. This function depends on tight junctions, of which zonula occludens (ZO)-1 is a major component. The authors have investigated the effects of hypoxia on ZO-1 localization and expression in the rabbit corneal epithelium in vivo. METHODS A polymethylmethacrylate (PMMA) or rigid gas-permeable (RGP) lens was applied to one eye each of albino rabbits for 24 hours. The structure of the corneal epithelium was examined by in vivo confocal microscopy, and epithelial barrier function was evaluated by measurement of central corneal thickness. The distribution and expression of ZO-1 in the corneal epithelium were examined by immunofluorescence analysis and by immunoblot and reverse transcription-polymerase chain reaction analyses, respectively. RESULTS Application of a PMMA lens, but not that of an RGP lens, resulted in a reduction in cell size at the surface of the corneal epithelium, compared with that in control eyes, and an increase in central corneal thickness. Immunofluorescence analysis revealed a continuous pattern of ZO-1 immunoreactivity around the perimeter of superficial corneal epithelial cells in control eyes or in eyes treated with an RGP lens. In contrast, the pattern of ZO-1 staining was discontinuous and patchy in eyes treated with a PMMA lens. Amounts of ZO-1 mRNA and protein in the corneal epithelium were reduced by application of a PMMA lens but not by that of an RGP lens. CONCLUSIONS Hypoxia at the ocular surface induced the disruption of tight junctions between superficial cells in the rabbit corneal epithelium in vivo.