gambogic-acid and Diabetic-Retinopathy

Diabetic retinopathy (DR) is a serious microvascular complication of diabetes. Gambogic acid has been reported to have anti-inflammatory effect. However, the effect of GA on inflammatory response of ARPE-19 cells remains unclear. In our study, ARPE-19 cells were stimulated by palmitic acid (PA) induction in the presence of 30 mM glucose and then treated with 0.5, 1, 2, 5, 10, or 20 μM GA. CCK-8 assay showed that cell viability was increased by GA treatment at doses of 0.5, 1, and 2 μM instead of higher doses. ELISA analysis found that GA dose-dependently reduced the production of pro-inflammatory mediators TNF-α and IL-1β. Western blot indicated that GA downregulated the expression of NLRP3 inflammasome components including TXNIP, NLRP3, ASC, cleaved-caspase-1, and cleaved-IL-1β in a dose-dependent manner. In addition, Western blot and immunofluorescence analysis suggested that GA effectively increased the protein level of nuclear factor E2-related factor-2 (Nrf2). RT-qPCR showed that GA significantly increased the mRNA levels of Heme oxygenase-1 (HO-1) and NADPH:quinone oxidoreductase1 (NQO1). Furthermore, Nrf2 siRNA transfection confirmed the above effects of GA. In total, subtoxic doses of GA significantly flattened the inflammatory response induced by HG and PA in ARPE-19 cells via modulating the Nrf2 signaling pathway.

Topics: Cell Line; Diabetic Retinopathy; Humans; Inflammation; NF-E2-Related Factor 2; Palmitic Acid; Xanthones

Gambogic acid (GA) is one of active components of Chinese medicine gamboges resin. Diabetic retinopathy (DR) is a most serious microvascular complication of diabetes and also the leading cause of blindness. The aim of this study is to evaluate the beneficial effect of GA on diabetes-induced retinal angiogenesis and further explore the potential mechanisms.. High glucose (HG)-treated RF/6A cells and STZ-induced diabetic mice were used as in vitro and in vivo models. Then the effects of GA on proliferation, migration and tube formation in RF/6A cells and pathomorphological changes in STZ-induced diabetic mice were determined. The activation of HIF-1α/VEGF and PI3K/AKT signaling pathways was assessed by various molecular biological experiments.. According to our results, GA inhibited HG-induced proliferation, migration and tube formation in choroid-retinal endothelial RF/6A cells. The upregulation of HIF-1α and VEGF induced by HG in RF/6A cells was restrained by GA treatment significantly. Moreover, GA suppressed retinal pathomorphological changes and angiogenesis in STZ-induced diabetic mice in vivo, and also inhibited the activation of HIF-1α/VEGF pathway induced by diabetics. Finally, GA suppressed the activation of PI3K/AKT signaling pathway in STZ-induced diabetic mice in vivo and in HG-induced RF/6A cells in vitro. Further activation of PI3K/AKT pathway by IGF-1 restrained the beneficial effect of GA in RF/6A cells.. Our results provide evidence that GA may ameliorate diabetes-induced retinal angiogenesis, which are proofs that GA may be developed as a potential drug for treating DR.

Topics: Animals; Antineoplastic Agents, Phytogenic; Cell Movement; Cell Proliferation; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Glucose; Hypoxia-Inducible Factor 1, alpha Subunit; Macaca mulatta; Male; Mice, Inbred C57BL; Oncogene Protein v-akt; Phosphoinositide-3 Kinase Inhibitors; Retinal Neovascularization; Signal Transduction; Vascular Endothelial Growth Factor A; Wound Healing; Xanthones