title: Complement factor h is critical in the maintenance of retinal perfusion.
abstract: Vascular pathologies are known to be associated with age-related macular degeneration. Recently, age-related macular degeneration was associated with a single-nucleotide substitution of the complement factor H (CFH) gene, part of the alternative pathway of the complement system, a critical element in the innate immune response. Such polymorphisms are found in more than 50% of cases of age-related macular degeneration. Here we show that the absence of CFH causes an autoimmune response that targets the vascular endothelium of both the inner and outer retinal vascular networks. In CFH-knockout (cfh(-/-)) mice, C3 and C3b, key components of the complement system, are progressively deposited on retinal vessels, which subsequently become restricted and wither, resulting in a reduction of retinal blood supply. This result leads to increased oxygen stress. While such effects are not systemic, these structural changes are mirrored in functional changes with a substantial decline in retinal blood flow dynamics. When the system is challenged functionally by laser-induced choroidal neovascularization, fluorescein leakage was significantly smaller in cfh(-/-) mice compared with controls, likely due to reduced retinal perfusion. These data reveal that in both the presence and absence of exogenous challenge to the innate immune system, CFH is required to maintain normal levels of retinal perfusion. It is likely that C3 and C3b accumulation in the aged CFH-deficient retina is associated with complement-mediated retinal endothelium destruction.
authors: Institute of Ophthalmology, University College London, GlaxoSmithKline Medicine'sResearch Centre, Stevenage, Herts, United Kingdom.
authors: Peter
authors: P
authors: Lundh von Leithner
authors: Jaimie Hoh
authors: JH
authors: Kam
authors: James
authors: J
authors: Bainbridge
authors: Ian
authors: I
authors: Catchpole
authors: Gerald
authors: G
authors: Gough
authors: Peter
authors: P
authors: Coffey
authors: Glen
authors: G
authors: Jeffery
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D003176:Complement C3 / Q000378:metabolism; D003179:Complement C3b / Q000378:metabolism; D017242:Complement Factor H / Q000235:genetics / Q000378:metabolism*; D005451:Fluorescein Angiography; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D015861:Retinal Neovascularization / Q000235:genetics / Q000378:metabolism*; D012171:Retinal Vessels / Q000378:metabolism* / Q000473:pathology*
chemical_list: D003176:Complement C3; D003179:Complement C3b; D017242:Complement Factor H