Altered proportion of CCR2+ and CX3CR1+ circulating monocytes in neovascular age-related macular degeneration and polypoidal choroidal vasculopathy

BACKGROUND: We investigated the expression of chemokine receptors CCR2 (C-C chemokine receptor) 2 and CX3CR1 (C-X3-C receptor 1) on circulating monocyte subsets in patients with neovascular age-related macular degeneration (AMD) and patients with polypoidal choroidal vasculopathy (PCV).

METHODS: We recruited patients with neovascular AMD, patients with PCV and age-matched healthy controls for this prospective case-control study. All participants underwent comprehensive clinical examination and imaging. Freshly sampled venous blood was prepared for flow cytometry, where we determined the proportion of CCR2+ - and CX3CR1+ -positive cells in monocyte subsets identified using monocyte identification and subgrouping surface markers CD14, CD16 and HLA-DR.

RESULTS: Patients with neovascular AMD had significantly increased proportion of CCR2+ and CX3CR1+ non-classical monocytes. PCV type 1 was associated with significantly increased CCR2+ and CX3CR1+ in all monocyte subsets when compared to PCV type 2.

CONCLUSIONS: Neovascular AMD is associated with increased expression of angiogenesis-associated chemokine receptors in the pro-inflammatory non-classical monocytes. PCV differs from neovascular AMD immunologically and show immunological heterogeneity across angiographic subtypes.