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C3aR1-Deletion Delays Retinal Degeneration in a White-Light Damage Mouse Model
Verena Behnke1, Anne Wolf1,2, Mandy Hector1
1Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.
Investigative Ophthalmology & Visual Science
|January 8, 2025
Summary
Targeting the C3a receptor (C3aR1) in mice partially protected the retina from light-induced degeneration by reducing complement-mediated damage. This suggests C3aR1-targeted therapy may benefit dry age-related macular degeneration (AMD) patients.
Area of Science:
- Ophthalmology
- Immunology
- Neuroscience
Background:
- Persistent microglial activation is implicated in retinal degenerative diseases like age-related macular degeneration (AMD).
- Dysregulation of the alternative complement pathway is a key driver of AMD, with microglia playing a role in complement production and signaling.
- Anaphylatoxin signaling influences microglial activity in the retina.
Purpose of the Study:
- To investigate the role of anaphylatoxin signaling, specifically via complement component 3a receptor 1 (C3aR1) and complement component 5a receptor 1 (C5aR1), in microglial activity and retinal degeneration.
- To model dry AMD using light-induced retinal degeneration in knockout (KO) mice lacking these receptors.
Main Methods:
- Complement component 3a receptor 1 (C3ar1) or complement component 5a receptor 1 (C5ar1) knockout (KO) and wildtype (WT) mice were exposed to bright white light (10,000 lux for 30 minutes).
- Transcriptome changes, Iba1+ cell migration, and retinal thickness were analyzed 4 days post-exposure.
- Full body KO mice for C3aR1 and C5aR1 were utilized.
Main Results:
- Deletion of C3aR1 or C5aR1 did not mitigate Iba1+ cell migration or reduce complement factor expression post-light damage compared to WT mice.
- However, C3aR1 KO mice exhibited a partial rescue of retinal thickness.
- This partial rescue in C3aR1 KO mice correlated with significantly reduced membrane attack complex (MAC) formation in the outer retina.
Conclusions:
- Deletion of C3aR1 does not modulate mononuclear phagocyte activity but does diminish retinal degeneration.
- The protective effect is attributed to interference with the complement pathway, leading to decreased MAC assembly.
- Targeting C3aR1 presents a potential therapeutic strategy for patients with dry AMD.
