Prevention of Inflammation, Neovascularization, and Retinal Dysfunction by Kinin B1 Receptor Antagonism in a Mouse Model of Age-Related Macular Degeneration.

The kallikrein-kinin system (KKS) contributes to vascular inflammation and neovascularization in age-related macular degeneration (AMD), particularly via the kinin B1 receptor (B1R). The aim of the present study was to determine the protective effects of the topical administration of the B1R antagonist (R-954) on inflammation, neovascularization, and retinal dysfunction in a murine model of neovascular AMD. Choroidal neovascularization (CNV) was induced in C57BL6 mice using an argon laser. A treatment with ocular drops of R-954 (100 μg/15 μL, twice daily in both eyes), or vehicle, was started immediately on day 0, for 7, 14, or 21 days. CNV, invasive microglia, and B1R immunoreactive glial cells, as well as electroretinography alterations, were observed within the retina and choroid of the CNV group but not in the control group. The staining of B1R was abolished by R-954 treatment as well as the proliferation of microglia. R-954 treatment prevented the CNV development (volume: 20 ± 2 vs. 152 ± 5 × 104 µm3 in R-954 vs. saline treatment). R-954 also significantly decreased photoreceptor and bipolar cell dysfunction (a-wave amplitude: -47 ± 20 vs. -34 ± 14 µV and b-wave amplitude: 101 ± 27 vs. 64 ± 17 µV in R-954 vs. saline treatment, day 7) as well as angiogenesis tufts in the retina. These results suggest that self-administration of R-954 by eye-drop treatment could be a promising therapy in AMD to preserve retinal health and vision.