MiR-15b在糖尿病增殖性视网膜病变进展中的作用机制

Proliferation diabetic retinopathy (PDR) is one of the most serious microvascular diseases derived from excessive microvessel formation. Currently, PDR has a high morbidity in Yunnan Province. We and others have showed that plasma vascular endothelial growth factor (VEGF) in PDR patients was significantly higher than that of non-proliferation diabetic retinopathy (NPDR) patients and normal controls(NDR).VEGF induced proliferation of vascular endothelial cells and formation of new blood vessels (angiogenesis). We also found the expression of miR-15b was decreased in plasma of diabetic patients and in retina of diabetic rats. VEGF could inhabit miR-15b expression,which further inhibit the proliferation of endothelial cells induced by VEGF. Hitherto, there is no study to characterize the exact role of miR-15b in the development of PDR. In this study, we performed experiments at both molecular and cellular levels, as well as using in vivo animal models to examine: 1. VEGF and its signal transduction in regulation of miR-15b expression; 2. mechanism of miR-15b inhibition for proliferation of vascular endothelial cells and angiogenesis; 3. the role of miR-15b in the development of PDR in animal model. Our results will reveal the molecular and cellular mechanism of miR-15b in PDR and provide helpful information regarding the therapy of PDR in the future.

糖尿病视网膜增殖性病变（PDR）是微血管过度形成造成的微血管病变，在云南地区高发。本课题组和前人研究发现：PDR血浆中VEGF显著高于单纯型（NPDR）和正常人群（NDR），而VEGF诱导血管内皮细胞增殖和成血管增加；PDR病人血浆和大鼠视网膜组织中，miR-15b表达下降；在内皮细胞中VEGF抑制miR-15b表达，而miR-15b抑制VEGF促增殖效应。miR-15b是否参与调控PDR未见报道。本项目在前期发现的基础上，在细胞和分子层次，结合动物模型实验，集中探讨：1.VEGF及其信号通路对于miR-15b表达调控作用。2.miR-15b抑制血管内皮细胞增殖和成血管的机制。3.在体动物模型研究miR-15b与PDR发生和发展之间的关联及机制。研究结果有望揭示miR-15b在PDR发生和发展过程中分子调控机制，为将来在体干预糖尿病视网膜病变提供理论依据和潜在靶点。

糖尿病视网膜病变是糖尿病引起的眼部并发症，可以导致视网膜损伤，最终引起失明，其病理机制尚不清楚。本研究旨在阐明microRNA对糖尿病视网膜病变中的作用。通过基因芯片我们发现了与糖尿病视网膜病变有关的一些microRNA，经过生物信息学分析发现microRNA-15b在糖尿病视网膜病变中表达下降，而且与VEGF呈负相关，我们收集了123例糖尿病视网膜病变患者和115名糖尿病非视网膜病变的患者血清，用实时PCR方法测定miR-15b，结果显示在糖尿病视网膜病变患者中miR-15b下降且与糖尿病视网膜病变发生相关。而且对GK大鼠的在体研究发现，过表达的miR-15b可以抑制糖尿病视网膜病变的发生。体外研究发现miR-15b可以抑制人视网膜血管上皮细胞的增殖，进一步的研究显示外周血的miR-15b可以到达视网膜血管上皮细胞，有剂量依赖性的抑制视网膜血管内皮细胞的增殖和和抑制VEGF表达的作用。荧光造影显示miR-15b可结合VEGF的3’-UTR区，负向调控VEGF表达。本研究阐述了miR-15b参与了糖尿病视网膜病变的机理，对临床实践有一定的指导作用。