Investigation of the preventive effect of calcium on inflammation-mediated choroidal neovascularization

Abstract

Aims: Age-related macular degeneration (AMD) is a leading cause of irreversible blindness in elderly people. The pathogenesis of neovascular AMD is known but is closely related to inflammation and choroidal neovascularization (CNV). The aim of this study was to investigate the anti-inflammatory and anti-angiogenic effects of calcium on neovascular AMD. Main methods: Human retinal pigment epithelial cells (ARPE-19) were used to identify protein markers of inflammation induced by differentiated macrophages. Choroidal neovascularization (CNV) mouse model was established by rupturing the Bruch's membrane using laser photocoagulation in C57BL/6 mice. Mice were divided into the following groups: untreated control and calcium supplemented. The expression levels of toll-like receptor isotype (TLR) 4, nuclear factor kappa B (NF-kappa B), hypoxia-inducible factor-1 alpha (Hif-1 alpha), and vascular endothelial growth factor (VEGF) were investigated to check whether calcium supplementation results in suppression of inflammation and has an anti-angiogenic effect. CNV was evaluated by immunofluorescence staining on choroidal flat mounts. Key finding: The inflammation-induced expression of TLR4, NF-kappa B, and Hif-1 alpha was decreased in ARPE-19 cells after calcium supplementation. Inhibition of the transcriptional activation of ARPE-19 cells by Hif-1 alpha suppression resulted in decreased VEGF expression. In the laser-induced CNV mouse model, calcium supplementation inhibited inflammatory mediators and neovascularization in the retinal tissue. Significance: Supplementation with calcium seems to constrain inveterate symptoms of neovascular AMD by inhibiting inflammation and angiogenesis in the laser-induced CNV mouse model.