Complement C3/C3aR Signaling Pathway Inhibition Ameliorates Retinal Damage in Experimental Retinal Vein Occlusion.

PURPOSE: Retinal vein occlusion (RVO) is a common retinal vascular disease that severely threatens visual function. This study aims to elucidate the role of the complement C3/C3aR signaling pathway in a laser-induced RVO mouse model and to explore its potential as a therapeutic target.

METHODS

RVO was induced in C57BL/6J mice using laser photocoagulation combined with photosensitizer dye administration. Two days later, retinal tissues were collected for bulk RNA sequencing. The activation of the C3/C3aR signaling pathway was validated through RT-qPCR and Western blot. The C3aR antagonist SB290157 (C3aRA) was administered intravitreally and retinal morphological and functional changes were examined 1, 2, and 8 days later by optical coherence tomography (OCT), fundus photography (FP), and fluorescein angiography (FA), optomotor response (OKR) test, and electroretinogram (ERG).

RESULTS

RVO mice exhibited marked increases in retinal thickness (P < 0.001) and fluorescence leakage (P < 0.01) compared to the sham-laser group. Bulk RNA-seq revealed significant upregulation of the complement pathway. Elevated expression of C3 and C3aR (P < 0.05) was confirmed by RT-qPCR and Western blot. Blocking C3aR with SB290157 significantly alleviated RVO-induced retinal edema, vascular leakage, and structural damage. Functional assessment showed that SB290157 treatment significantly improved contrast sensitivity (P < 0.05), increased b-wave (P < 0.001), and oscillatory potentials (Ops) amplitudes (P < 0.05) in RVO mice. RNA-seq analysis demonstrated that SB290157 significantly reduced the inflammatory mediator-related pathways and upregulated visual perception pathways (P < 0.05).

CONCLUSIONS

The complement C3/C3aR signaling pathway is critically involved in RVO-induced retinal damage and targeting this pathway may be a promising approach for RVO treatment.