Human retinal pigment epithelium cell changes and expression of αB-crystallin -: A biomarker for retinal pigment epithelium cell change in age-related macular degeneration

Objective: To examine changes in the retinal pigment epithelium (RPE) in eyes with age-related macular degeneration (AMD) and specifically to characterize alpha beta-crystallin expression in RPE cells as a biomarker in this disease. Methods: Maculae from human patients diagnosed as having AMD or from age-matched control eyes were isolated, cryosectioned, and analyzed immunohistochemically for alpha beta-crystallin and for cell type-specific markers. Results: In eyes with dry and wet AMD, alpha beta-crystallin was heterogeneously expressed by a subpopulation of RPE cells in the macular region (frequently in cells adjacent to drusen) and in areas of RPE hypertrophy associated with wet AMD. In contrast, alpha beta-crystallin was not detected at significant levels in control RPE. Conclusion: Accompanying the formation of drusen in early-stage and late-stage AMD, RPE cells undergo change to express alpha beta-crystallin. Clinical Relevance: The detection of alpha beta-crystallin in the RPE of patients with early and advanced AMD implicates this as an AMD biomarker. Sporadic expression of alpha beta-crystallin by RPE cells localized adjacent to drusen in early AMD indicates that changes in the gene expression of RPE cells accompany early stages of the disease and introduces novel potential targets for AMD therapy.