Role of Complement Regulatory Protein, CD59, in the Development of Choroidal Neovascularization in a Mouse Model of Wet-Type Age-Related Macular Degeneration

Abstract

Purpose:: The purpose of this study was to understand the role of complement regulatory protein - CD59a in regulating complement activation and MAC formation in the development of laser-induced CNV in mice.

Methods:: CNV was induced by laser photocoagulation in the C57BL/6 and CD59 deficient (Cd59a ^-/-) mice using an Argon laser. In an another set of experiments, C57BL/6 mice were injected with recombinant soluble mouse CD59a-IgG2a fusion (rsCD59a-Fc) protein via intraperitoneal (ip) and intravitreal routes 24 h prior to laser. Animals from each group were sacrificed on day 1, 3, 5, and 7 post-laser. Retinal pigment epithelium (RPE)-choroid-scleral flat mounts prepared from harvested eyes were stained for elastin and the incidence of CNV was determined by confocal microscopy. The size of the CNV complex was graded by morphometric analysis of the images. RPE-choroidal tissues were pooled separately for RT-PCR and Western blot analysis of CD59a and growth factors.

Results:: CD59a (both mRNA and protein) was down-regulated during laser-induced CNV. Our results demonstrated that Cd59a ^-/- mice developed CNV complex early in the disease process. Increased MAC deposition was also observed in these Cd59a ^-/- mice. Administration of rsCD59a-Fc inhibited the development of CNV complex in the mouse model by blocking MAC formation and also inhibited the expression of angiogenic growth factors compared to control animals.

Conclusions:: In conclusion, our results demonstrate that that CD59a plays a crucial role in regulating complement activation and MAC formation essential for the release of growth factors that drive the development of laser-induced CNV in mice. Thus, our results suggest that the inhibition of complement by recombinant soluble CD59 may provide a novel therapeutic alternative to current treatments.

Keywords: age-related macular degeneration • choroid: neovascularization • inflammation