Abstract
Purpose To measure the concentrations of various cytokines in the aqueous humor from patients with different stages of diabetic retinopathy. Methods All selected cataract patients were categorized into 4 groups: the control group (patients without diabetes), nonretinopathy (NDR) group (diabetic patients without retinopathy), nonproliferative diabetic retinopathy (NPDR) group, and proliferative diabetic retinopathy (PDR) group. The aqueous concentrations of interleukin- (IL-) 1β, IL-2, IL-4, IL-5, IL-6, IL-10, interferon-γ, tumor necrosis factor-α, and vascular endothelial growth factor (VEGF) from patients were measured using the cytometric bead array technique. Results In this study, 10, 22, 15, and 14 patients were included in the control, NDR, NPDR, and PDR groups, respectively. No difference was observed in the aqueous concentrations of all cytokines between the control group and the NDR group. By contrast, comparison of these groups revealed that the aqueous concentrations of most inflammatory cytokines were significantly higher in the PDR and NPDR groups. In addition, the concentrations of IL-2, IL-5, and VEGF were higher in the PDR group than those in the NPDR group. Conclusions Aqueous concentrations of various cytokines increased with the severity of patients' diabetic retinopathy. This finding implies that these cytokines might play a role in the progression of diabetic retinopathy.
Highlights
Diabetic retinopathy (DR), a major complication in patients with diabetes, is a leading cause of visual blindness globally [1]
The cytometric bead array (CBA) analysis results showed no difference in the aqueous concentrations of cytokines between the control group and the NDR group
The concentrations of IL-2, IL-5, and vascular endothelial growth factor (VEGF) were higher in the proliferative diabetic retinopathy (PDR) group than in the nonproliferative diabetic retinopathy (NPDR) group (Tables 2 and 3)
Summary
Diabetic retinopathy (DR), a major complication in patients with diabetes, is a leading cause of visual blindness globally [1]. Evidence shows that increasing concentrations of various inflammatory mediators and proinflammatory cytokines in diabetic eyes may lead to microvascular occlusion and breakdown of the blood-retinal barrier, followed by vascular leakage, capillary nonperfusion, neurodegeneration, and neovascularization [2, 3]. Measuring various cytokines in patients with different stages of DR may facilitate the evaluation of the inflammatory status at each stage and the exploration of their effects on disease progression. The concentrations of many mediators and pathogens in intraocular tissues are different from those in systemic circulation because of the blood-eye barrier. Sampling the aqueous humor is the most effective method for evaluating the cytokines and mediators produced by intraocular tissues [5]. Only less than 200 μL of the aqueous humor can be obtained per sampling because of its total amount in the anterior chamber and surgical limitations.
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