Characterization Of Drusen Component And Possible Involvement Of Autoimmunity In Early And Late Onset Macular Degeneration Cynomolgus Monkey (Macaca Fascicularis)

Abstract

Purpose: : To characterize molecular composition of drusen observed in two forms of macular degeneration cynomolgus monkeys, and to analyze the autoimmunity in late onset monkeys.

Methods: : Funduscopic and histological examinations were performed on family members in the pedigree for early onset monkeys, and 278 late onset monkeys (mean age = 16.94 y). The molecular composition of drusen was analyzed by immunohistochemistry and/or proteomic analysis using liquid chromatography ion spray mass spectrometer (LC–MS/MS). Retinal protein extract was blotted on to the nylon membrane for western blotting using serum from late onset monkeys. Identified antigen was expressed in bacteria and purified for ELISA assay.

Results: : Drusen in both early and late onset macular degeneration monkeys showed immunoreactivities for apolipoprotein E, amyloid P component, complement component C5, the terminal C5b–9 complement complex, vitronectin, and membrane cofactor protein. LC–MS/MS analyses identified 60 proteins in drusen, including number of common components with drusen in human AMD, such as annexins, crystallins, immunoglobulins, and complement components. Autoimmunity was found in late onset monkeys with elevation of Annexin II and µ–crystallin antibodies.

Conclusions: : Monkey drusen both in early and late onset forms of macular degeneration had common components with human AMD drusen, indicating that chronic inflammation mediated by complement activation might be also involved in the formation of drusen in these monkeys. The results suggest that isolation of the disease–causing gene for early onset monkeys could offer important clues to reveal the pathway which trigger drusen formation, and might provide new candidate locus for human AMD.

Keywords: age-related macular degeneration • drusen • proteomics