Early local activation of complement in aqueous humour of patients with age-related macular degeneration

To investigate complement activation in aqueous humour of patients with early, intermediate and neovascular age-related macular degeneration (AMD).

Aqueous humour of 79 AMD patients (early, intermediate and neovascular) and 77 age-matched controls was prospectively collected. The levels of the complement protein 3 (C3), activation products complement factor 3a (C3a) and Ba, C3b/iC3b, complement factors B, H and I (CFB, CFH and CFI), and total protein concentration were measured. Data were modelled using covariate analysis to assess the impact of age and glaucoma status of patients and total protein concentration of samples on complement protein concentration across groups.

C3a concentration was significantly increased in the aqueous humour of early (p = 0.016), intermediate (p = 0.003) and neovascular (p = 0.018) AMD patients, whilst C3 concentration was significantly increased in early AMD patients only (p = 0.019). Levels of CFB and CFH were significantly increased in the aqueous humour of neovascular AMD patients (p = 0.023 and p = 0.018, respectively).

Our findings provide evidence for early local complement dysregulation in AMD patients, suggesting that complement pathway inhibition may be a clinically relevant intervention for early stages of AMD.