Work

Intraocular complement activation is independent of systemic complement activation and is related to macular vascular remodelling in retinal vein occlusion

Year: 2024

Type: article

Abstract: Background Retinal vein occlusion (RVO) is a major cause of vision loss. The pathogenesis remains poorly defined although inflammation is known to play a critical role. In this study, we investigated the levels of complement proteins in the aqueous humour and plasma of RVO participants and the relationship between complement levels and retinal pathologies. Methods The plasma and aqueous humour were collected from 20 untreated RVO and 20 cataract patients. Retinal lesions were examined by fundus stereoscopy and optical coherence tomography angiography. The levels of C1q, C2, C4, C4b, C3, C3b/iC3b, C5, C5a, CFB, CFD, CFI, CFH, and MBL were measured using the Luminex® x MAP® multiplex assay. Results RVO patients had significantly higher levels of C4, C4b, C3b/iC3b, CFB, CFI, and CFH in the plasma and aqueous humour compared to controls. The aqueous levels of C1q, C2, C5, C5a, CFD and MBL were also significantly higher in RVO patients than in controls. C5a was below detectable limit in the plasma in 18 and 16 participants with cataract and RVO, respectively. The intraocular levels of C5a positively correlated with C2, C4, CFB, and CFH. The intraocular levels of C2, CFB, CFH, and MBL negatively correlated with the size of foveal avascular zone. The plasma levels of C4, C4b, C5, CFD positively correlated with their counterparts in the aqueous humour in cataract patients but not in RVO. Conclusions The intraocular complement activation in RVO is mediated by the classical and the alternative pathways and is largely independent of systemic complement activation. Intraocular complement activation is related to retinal oedema and vascular remodeling in RVO patients.

Source: BMC Ophthalmology

DOI: 10.1186/s12886-024-03781-3