Related Experiment Video
Updated: Jun 3, 2025
Imaging Ca2+ Dynamics in Cone Photoreceptor Axon Terminals of the Mouse Retina
Published on: May 6, 2015
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.
Purpose:
In the aging retina, persistent activation of microglia is known to play a key role in retinal degenerative diseases like age-related macular degeneration (AMD). Furthermore, dysregulation of the alternative complement pathway is generally accepted as the main driver for AMD disease progression and microglia are important producers of local complement and are equipped with complement receptors themselves. Here, we investigate the involvement of anaphylatoxin signaling, predominantly on Iba1+ cell activity, in light-induced retinal degeneration as a model for dry AMD, using anaphylatoxin receptor knockout (KO) mice.
Methods:
Bright white light with an intensity of 10,000 lux was applied for 30 minutes to complement component 3a receptor 1 (C3ar1) or complement component 5a receptor 1 (C5ar1) KO and wildtype (WT) mice. Analyses of transcriptome changes and migration activity of Iba1+ cells as well as retinal thickness were performed 4 days after light exposure.
Results:
Full body KO mice of either C3aR1 or C5aR1 were tested, but none led to mitigated migration of Iba1+ cells to the subretinal space or decreased expression of complement factors after light damage compared to WT mice. However, a partial rescue of retinal thickness was shown in C3aR1 KO mice, which was mirrored by significant less membrane attack complex (MAC) occurrence in the outer retina.
Conclusions:
We conclude that deletion of the anaphylatoxin receptor C3aR1 cannot modulate mononuclear phagocytes but diminishes retinal degeneration through interference with the complement pathway and thus decreased MAC assembling. C3aR1-targeted therapy may be considered for patients with dry AMD.
Insights
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.
