Adhesive properties of basal membranes of Bruch's membrane: immunohistochemical analysis of aging changes in adhesive proteins and lipids

Background: In addition to deposition of debris between the plasma and basa l membrane of the RPE, different types of early and late AMD-like drusen, c horoidal neovascularization and pigment epithelial detachments are characte rized by splitting of Bruch's membrane between the basement membrane of the RPE and the inner collagenous layer. Because these layers are normally att ached by adhesion molecules,the possible age-related regression of these ad hesion molecules in this structure was examined. Methods: The presence of the adhesion molecules laminin, fibronectin, colla gen IV and of lipid deposits was examined in 44 macular specimen (age 4-88 years). Results: Age-related regression of the adhesion molecules laminin,fibronect in and collagen IV was observed in the basment membrane of the RPE and the endothelium cells of the choriocapillaris. This effect correlated with an i ncrease in lipid deposits. Conclusion: The regression of adhesion molecules, especially in the basemen t membrane of the RPE in association with incresased lipid deposits in Bruc h's membrane, may explain the development of a "cleavage edge" for the spli tting of Bruch's membrane between the basement membrane of the RPE and the inner collagenous layer.