Complement Components Showed a Time-Dependent Local Expression Pattern in Constant and Acute White Light-Induced...

Area of Science:

• Ophthalmology
• Immunology
• Molecular Biology

Background:

• Photoreceptor cell death from light exposure causes retinal degeneration.
• Complement system dysregulation exacerbates light-induced damage, but its progression is unclear.

Purpose of the Study:

• To investigate the local and time-dependent complement system activation in response to light-induced retinal degeneration (LD) in mice.
• To compare complement factor expression and cellular changes in acute vs. constant LD models.

Main Methods:

• Induced LD in Balb/c mice using constant (1000 lux, 24h) or acute (5000 lux, 0.5h) light.
• Quantified complement protein and mRNA (C1s, CFB, MASP-1, C3, C4, C9) in retina and RPE/choroid at 1 and 3 days post-LD.
• Assessed apoptosis, microglia/macrophage migration, gliosis, and C3d deposition histologically.

Main Results:

• Both LD models showed similar apoptosis, gliosis, and immune cell infiltration.
• Early upregulation of complement mRNA (C1s, CFB, MASP-1, C3, C4, C9) observed in RPE/choroid at 1 day post-LD.
• Intraretinal mRNA for C1s, CFB, C3, C4 increased at 1 day (constant LD) or 3 days (acute LD).
• Retinal C3 protein and C3d staining increased at 1 day post-LD.
• RPE/choroid C1s-complex protein increased at 3 days post-LD.

Conclusions:

• Light-induced retinal degeneration is associated with local complement system activation.
• Complement regulation on mRNA and protein levels shows similar time-dependent progression in both LD models, with exceptions in intraretinal mRNA expression.
• Understanding the temporal dynamics of complement activity can guide therapeutic strategies for retinal degeneration.