Dry age-related macular degeneration like pathology in aged 5XFAD mice: Ultrastructure and microarray analysis. Mus musculus

Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly. There are two types of AMD: dry AMD and wet AMD. While laser-induced choroidal neovascularization has been used extensively in the studies of wet AMD by presenting the main features of human wet AMD, there was no established mouse model which fully recapitulates the cardinal features of human dry AMD. In this regard, lack of appropriate mouse model for dry AMD hampered the translational research on the pathogenesis and development of therapeutic agents. We recently suggested that 5XFAD mice could be a mouse model of dry AMD with regard to the amyloid beta (Aβ) related pathology. In this study, using transmission electron microscope, we analyzed ultrastructure of retinal pigment epithelium (RPE) of 5XFAD mice. Of importance, aged 5XFAD mice had ultrastructural changes of RPE and Bruch’s membrane compatible with cardinal features of dry AMD, including loss of apical microvilli and basal infolding of RPE, increased thickness of Bruch’s membrane, basal laminar and linear deposits, and accumulation of lipofuscin granules and undigested photoreceptor outer segment-laiden phagosomes. Using a threshold of 1.2 fold difference, we found “564” differentially expressed genes of which “190” were up-regulated and “374” were down-regulated in the RPE complex of aged 5XFAD mice. These altered genes were implicated in the pathogenesis of AMD including inflammation and immune response-related genes and retinol metabolism-related genes. Taken together, we suggest that aged 5XFAD mice can be used for dry AMD mouse model. Overall design: All 5XFAD mice used were heterozygotes with respect to the transgene, and non-transgenic wild-type littermate (WT) mice served as controls.