Purpose: To determine whether there is an age-related increase of pentosidine in human Bruch's membranes and to localize pentosidine and carboxymethyllysine (CML), two well-characterized, advanced glycation end products (AGEs) in aged human Bruch's membranes and choroid in vivo.
Methods: Human Bruch's membrane samples were isolated from the retinal pigment epithelium (RPE) and choroid and subjected to reversed-phase high-performance liquid chromatography to determine pentosidine content. A polyclonal anti-pentosidine antibody and a monoclonal antibody specific for carboxymethyllysine were used to localize AGEs in 20-month-old nondiabetic, 82-year-old nondiabetic, and 82-year-old diabetic globes.
Results: Human Bruch's membranes (n = 20) showed a linear age-dependent increase in pentosidine that reached approximately 0.17 millimoles pentosidine per mole hydroxyproline in late life (r = 0.896; P < 0.001). Immunohistochemical evaluation showed evidence of pentosidine in Bruch's membrane, choroidal extracellular matrix, and vessel walls in the 82-year-old nondiabetic and diabetic globes. A similar staining pattern was found with the anti-CML antibody. Basal laminar deposits and drusen stained with both antibodies in the elderly nondiabetic eye. In contrast, neither antibody stained the 20-month-old tissue.
Conclusions: We provide biochemical and immunohistochemical evidence for the formation of pentosidine and CML structures in human Bruch's membrane and choroid with age. These changes could promote aging of the RPE-Bruch's membrane-choroid complex.