Abstract
Purpose To analyze the effect of intravitreal aflibercept injections on systemic levels of insulin-like growth factor-1 and vascular endothelial growth factor-A in patients with diabetic retinopathy and age-related macular degeneration. Methods Vascular endothelial growth factor-A and insulin-like growth factor-1 levels were determined before and one week and four weeks after intravitreal injection of aflibercept (2.0 mg/50 μl) for 19 patients with age-related macular degeneration (mean age, 76 ± 11 years) and 18 patients with diabetic retinopathy (mean age, 64 ± 14 years). Twenty-two healthy individuals were enrolled as controls. Results A significant decline in systemic vascular endothelial growth factor-A level, from 43 (30–57) pg/ml at baseline to 8 (8–8) pg/ml (p < 0.001) at week one and 17 (8–25) pg/ml (p=0.0054) at week four, was observed in the age-related macular degeneration group. In the diabetic retinopathy group, vascular endothelial growth factor-A levels declined from 53 (35–117) pg/ml to 2 (1–5) pg/ml (p < 0.0001) one week after injection and 16 (13–22) pg/ml four weeks after injection (p=0.0327). At baseline, systemic insulin-like growth factor-1 concentration was higher in the diabetic retinopathy group (57 [37–99] pg/ml) than in the age-related macular degeneration group (35 [24–51] pg/ml) (p=0.0056). A subgroup analysis showed that patients in the proliferative diabetic retinopathy subgroup had significantly higher systemic insulin-like growth factor-1 concentrations (71 [44.7–243] pg/ml) than those in the nonproliferative diabetic retinopathy subgroup (43 [29–66] pg/ml) (p=0.0048). Conclusions The difference between the baseline systemic insulin-like growth factor-1 levels of the age-related macular degeneration and diabetic retinopathy groups and the higher insulin-like growth factor-1 levels in the proliferative diabetic retinopathy subgroup one week after aflibercept therapy suggest that insulin-like growth factor-1 may play a role in the pathomechanism of diabetic retinopathy.
Highlights
Diabetic retinopathy (DR) and age-related macular degeneration (AMD) are the most common causes of vision impairment among people in industrialized countries [1–3]
We observed a significant decrease in systemic vascular endothelial growth factor (VEGF)-A levels in the AMD and DR groups one week and four weeks after intravitreal aflibercept therapy
E baseline insulin-like growth factor (IGF)-1 level was significantly higher in the DR group than in the AMD group
Summary
Diabetic retinopathy (DR) and age-related macular degeneration (AMD) are the most common causes of vision impairment among people in industrialized countries [1–3]. Numerous risk factors leading to the development of DR [4, 5] or neovascular AMD (nAMD) [6] have been proposed, the etiologies of both diseases are still not fully elucidated. Both diseases are related to the presence of a complex inflammatory process that involves the overexpression of proangiogenic factors, which leads to choroidal neovascularization and consecutive loss of vision [7, 8]. It is known that insulin-like growth factor (IGF) is involved in the regulation of neovascularization. It plays a role in the expression of VEGF. It plays a role in the expression of VEGF. erefore, IGF potentially participates in the pathogenesis of diseases associated with pathological angiogenesis [10, 11]
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