Abstract
Age-related macular degeneration (AMD) is one of the main causes of visual impairment in adults. Visual deterioration is more prominent in neovascular AMD with choroidal neovascularization (CNV). Clinical and postmortem studies suggested that complement system activation might induce CNV. In this study, we demonstrated that an anti-mouse complement component 5 (C5) antibody targeting MG4 domain of β chain effectively inhibited CNV which was induced by laser photocoagulation in mice. The targeted epitope of this anti-C5 antibody was different from that of currently utilized anti-C5 antibody (eculizumab) in the MG7 domain in which a single nucleotide polymorphism (R885H/C) results in poor response to eculizumab. Even with targeting MG4 domain, this anti-C5 antibody reduced production of C5a, monocyte chemoattractant protein-1 and vascular endothelial growth factor to prevent infiltration of F4/80-positive cells into CNV lesions and formation of CNV. Furthermore, anti-C5 antibody targeting MG4 domain induced no definite toxicity in normal retina. These results demonstrated that anti-C5 antibody targeting MG4 domain inhibited CNV in neovascular AMD.
Highlights
Complement dysregulation induces the pathogenesis of age-related macular degeneration (AMD), the leading cause of blindness in adults over 50 years of age [1, 2]
As component 5 (C5) and its cleaved forms of effector proteins (C5a and C5b) are expressed in human choroidal neovascularization (CNV) [8, 9, 13] and associated with the progression of neovascular Age-related macular degeneration (AMD) [12, 13], C5a is elevated in retinal pigment epithelial (RPE)-choroid-scleral complexes [8] and the level of C5a is related with the degree of CNV formation in the laser-induced CNV model in mice [34]
We demonstrated that C5a was elevated in RPE-choroid-scleral complexes, of which the highest value was evident at 6 hours after laser photocoagulation (Figure 3A and Supplementary Figure 1A)
Summary
Complement dysregulation induces the pathogenesis of age-related macular degeneration (AMD), the leading cause of blindness in adults over 50 years of age [1, 2]. Genetic variants in complement component 3 (C3), complement component 2 and complement factor B are known to be associated with AMD [5, 6]. C5a are localized to drusen, the proximity of retinal pigment epithelial (RPE) cells and Bruch’s membrane [8]. In line with these results, drusen in the eyes of patients with AMD are immunopositive with complement component 5 (C5) and C5b-9 complex [9] and the C5 components are present in the drusen and RPE cells overlying or directly adjacent to the drusen [10]. Various complement inhibitors were in development for the treatment of AMD [14]
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