CX3CR1-dependent subretinal microglia cell accumulation is associated with cardinal features of age-related macular
Christophe Combadière1, Charles Feumi, William Raoul
1INSERM U543, Laboratoire d'Immunologie Cellulaire, Paris, France.
Abstract:
The role of retinal microglial cells (MCs) in age-related macular degeneration (AMD) is unclear. Here we demonstrated that all retinal MCs express CX3C chemokine receptor 1 (CX3CR1) and that homozygosity for the CX3CR1 M280 allele, which is associated with impaired cell migration, increases the risk of AMD. In humans with AMD, MCs accumulated in the subretinal space at sites of retinal degeneration and choroidal neovascularization (CNV). In CX3CR1-deficient mice, MCs accumulated subretinally with age and albino background and after laser impact preceding retinal degeneration. Raising the albino mice in the dark prevented both events. The appearance of lipid-bloated subretinal MCs was drusen-like on funduscopy of senescent mice, and CX3CR1-dependent MC accumulation was associated with an exacerbation of experimental CNV. These results show that CX3CR1-dependent accumulation of subretinal MCs evokes cardinal features of AMD. These findings reveal what we believe to be a novel pathogenic process with important implications for the development of new therapies for AMD.
Insights
Retinal microglial cells (MCs) accumulation, driven by CX3C chemokine receptor 1 (CX3CR1) dysfunction, is linked to age-related macular degeneration (AMD). This accumulation exacerbates key AMD features, suggesting new therapeutic targets.
Area of Science:
- Ophthalmology
- Immunology
- Cell Biology
Background:
- The precise role of retinal microglial cells (MCs) in the pathogenesis of age-related macular degeneration (AMD) remains incompletely understood.
- Microglial cells are key immune cells in the retina, and their dysfunction is implicated in various retinal diseases.
Purpose of the Study:
- To investigate the role of retinal microglial cells (MCs), specifically their CX3C chemokine receptor 1 (CX3CR1) expression and function, in the development and progression of age-related macular degeneration (AMD).
- To explore the link between CX3CR1 genetic variations, MC migration, and AMD risk.
Main Methods:
- Analysis of CX3CR1 expression in retinal MCs.
- Investigation of the CX3CR1 M280 allele's association with AMD risk.
- Examination of MC accumulation in human AMD retinas.
- Utilizing CX3CR1-deficient mice models to study MC behavior in response to aging, genetic background, and injury.
- Assessing the impact of environmental factors (dark rearing) on MC accumulation.
- Funduscopic evaluation of subretinal MCs in aged mice.
- Evaluating the effect of MC accumulation on experimental choroidal neovascularization (CNV).
Main Results:
- All retinal MCs express CX3CR1.
- Homozygosity for the CX3CR1 M280 allele, linked to impaired migration, correlates with increased AMD risk.
- In human AMD, MCs accumulate in the subretinal space at sites of degeneration and CNV.
- CX3CR1-deficient mice exhibit age- and background-dependent subretinal MC accumulation, which is exacerbated by laser injury.
- Dark rearing prevents these MC accumulation events in mice.
- Lipid-bloated subretinal MCs in aged mice resemble drusen.
- CX3CR1-dependent MC accumulation worsens experimental CNV.
Conclusions:
- CX3CR1-dependent accumulation of subretinal microglial cells is a critical factor that recapitulates cardinal features of age-related macular degeneration (AMD).
- This study identifies a novel pathogenic mechanism in AMD involving microglial cell dysfunction and accumulation.
- These findings have significant implications for developing new therapeutic strategies targeting microglial cells in AMD treatment.
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