CONFOCAL IMAGING OF THE ALPHA-6 AND BETA-4 INTEGRIN SUBUNITS IN THE HUMAN CORNEA WITH AGING

Purpose. The purpose of this study was to examine changes in the distr ibution of integrin subunits, alpha6 and alpha4, in the normal human c ornea with age. Methods. Thirty normal corneas were examined and divid ed into three groups; corneas from children younger than 2 years, corn eas from adults 29 to 70 years, and corneas from adults older than 70 years. The corneas were frozen and the sections were cut, double-stain ed with monoclonal antibodies to the integrin subunits, and visualized with Texas Red or fluorescein using confocal laser scanning microscop y. Computer imaging was conducted to determine differences. Results. T he alpha6, subunit was generally localized along the basal and lateral surfaces of basal epithelial cells and projected into Bowman's membra ne. The beta4 subunit was only present along the basal surface. Overal l, the major age-related difference was the loss of continuous a, and beta4 subunits along the basal surface of basal epithelial cells. When reconstructed images from corneas of individuals older than 70 years were optically sectioned en face, the alpha6 subunit appeared disconti nuous. If the same optical images were viewed from corneas of younger individuals, the staining was continuous. The number and distribution of hemidesmosomes along the basal lamina did not change with age in th e corneas examined. Conclusions. Using computer imaging associated wit h confocal laser scanning microscopy, we have demonstrated that there is an age-related change in the localization of the alpha6 and beta4 s ubunits.