Difference of intraocular cytokines between diabetic macular edema and macular edema due to retinal vein occlusion

Abstract

Purpose : The involvement cytokines in aqueous humor is important in the development and progression of diabetic macular edema (DME) and macular edema due to retinal vein occlusion (RVO-ME). In this study, the concentrations of cytokines in the aqueous humor of eyes with DME and RVO-ME were measured and compared.

Methods : Aqueous samples were obtained from 18 eyes with DME (DME group), 16 eyes with RVO-ME (RVO-ME group), and 16 eyes with normal controls (control group). The aqueous levels of cytokines including Interleukin (IL)-2, IL-5, IL-6, IL-8, IL-12p70, IL-13, monocytochemotactic protein-1 (MCP-1), macrophage inflammatory protein-1α (MIP-1α), Platelet-Derived Growth Factor (PDGF)-AA, Transforming growth factor-α (TGF-α), interferon- γ (IFN-γ), Epidermal growth factor (EGF), Fibroblast growth factor 2 (FGF2) and vascular endothelial growth factor (VEGF) were measured.

Results : The aqueous levels of IL-8, MCP-1, PDGF-AA, VEGF were higher and IL-13 was lower in the DME group compared to the control group. The aqueous levels of IL-8 and VEGF were higher in the RVO-ME group compared to the control group. Compared to the RVO-ME group, IL-6 and MCP-1 were significantly higher in the DME group. Correlation analyses revealed that IL-8 was positively and IFN-γ was negatively correlated with severity of macular edema in the DME group. In the RVO-ME group, IL-8 and VEGF were positively correlated with retinal ischemia. IL-8 and MCP-1 were positively correlated with VEGF in the RVO-ME group.

Conclusion : DME and RVO-ME could be expected to differ in pathogenesis of development, because the cytokine concentrations in the aqueous humor differ. The results suggest that the inflammatory reaction may be more activated in DME than RVO-ME and ischemic insult may play a central role in the development of RVO-ME.