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 basal membrane of the RPE, different types of early and late AMD-like drusen, choroidal neovascularization and pigment epithelial detachments are characterized by splitting of Bruch's membrane between the basement membrane of the RPE and the inner collagenous layer. Because these layers are normally attached by adhesion molecules,the possible age-related regression of these adhesion molecules in this structure was examined. Methods: The presence of the adhesion molecules laminin, fibronectin, collagen IV and of lipid deposits was examined in 44 macular specimen (age 4-88 years). Results: Age-related regression of the adhesion molecules laminin,fibronectin and collagen IV was observed in the basment membrane of the RPE and the endothelium cells of the choriocapillaris. This effect correlated with an increase in lipid deposits. Conclusion: The regression of adhesion molecules, especially in the basement membrane of the RPE in association with incresased lipid deposits in Bruch's membrane, may explain the development of a cleavage edge for the splitting of Bruch's membrane between the basement membrane of the RPE and the inner collagenous layer.