TLR3对视网膜色素上皮免疫和吞噬功能的调节与糖尿病视网膜病变相关性的研究

Diabetic retinopathy (DR) is a severe complication of diabetes mellitus and a leading cause of adult vision loss and blindness, whereas the pathogenesis of DR has not been well clarified yet. Breakdown of blood-retinal barrier (BRB) is one of the important pathological characteristics of DR. While extensive work has focused on the inner BRB which is composed of tight junctions between the endothelial cells in the past few years, much less attention has been carried towards the outer BRB—retinal pigment epithelial (RPE) cells, which also paly significant roles in the pathogenesis of DR. Our previous study found that the expression of toll-like receptor 3 (TLR3) on RPE cells cultured in high-glucose media was activated, which initiated inflammatory response downstream. Moreover, RPE cells separated from diabetic rats expressed higher level of TLR3 than normal controls. These data indicate regulation of RPE innate immunity by TLR3 contributes to the pathogenesis of DR. Also, the phagocytosis of outer rod segments by RPE may be disturbed in DR according to previous studies. The present study would investigate the significance of RPE immunity in DR both in vitro and in vivo, including: ①Mechanisms of RPE inflammatory response mediated by TLR3 activation; ②The relationship between TLR3 activation on RPE and DR; ③The regulation of RPE phagocytosis of rod outer segments by TLR3 and its relation to DR.

糖尿病视网膜病变（DR）是一种常见的糖尿病并发症，是成年人失明的重要原因。血-视网膜屏障的破坏是DR重要的病理改变。过去的研究主要关注内屏障—内皮细胞的改变，而对外屏障—视网膜色素上皮（RPE）的认识较少，但其重要性不容忽视。我们在前期研究中发现，体外培养的RPE细胞给予高糖刺激后可激活Toll样受体(TLR) 3信号通路；且糖尿病模型大鼠的RPE细胞上TLR3的表达明显高于正常组，提示TLR3对RPE免疫功能的调节可能是DR发生的机制之一。据文献报道，DR的发生可能还与RPE的吞噬功能受损相关。本项目拟从离体和在体两个层面，进行以下研究：①TLR3介导体外培养的RPE细胞固有免疫反应的机制；②利用糖尿病动物模型探讨RPE细胞TLR3的激活与DR的相关性；③TLR3对RPE吞噬功能的调节及其与DR的关系。目的是从新的角度阐释DR发生的机制，为临床干预提供思路。

糖尿病视网膜病变（diabetic retinopathy，DR）是糖尿病常见的并发症之一，在全球糖尿病人群中的发病率高达34.6%，其高致盲性已严重影响我国糖尿病患者的生活质量。以往对DR发病机制的研究多集中在血管内皮细胞上，但目前针对其已发现机制的治疗尚未取得突破性进展，因此从新的角度探寻DR的发病机制仍然是眼科基础研究中亟待解决的问题。视网膜色素上皮（retinal pigment epithelial, RPE）不仅构成了血-视网膜的外屏障，而且具有运输营养及代谢产物、吞噬脱落感光细胞、分泌免疫调节因子维持视网膜下腔免疫稳态等重要生理作用，近期越来越多的研究认识到其功能受损是DR发展的重要原因之一。本项目以固有免疫重要成员——Toll样受体3（Toll-like receptor 3，TLR3）信号通路为切入点，探讨RPE炎症反应激活及吞噬功能受损在DR进展过程中的作用。我们首先验证了RPE细胞中TLR3信号通路激活的级联反应，接下来通过体内、体外实验阐释了TLR3通路活化与DR发展的相关性，最后研究了TLR3激活对RPE细胞吞噬功能的损伤及机制。结果发现RPE细胞的TLR3活化后可进一步激活下游的转录因子IRF3和NF-κB，诱导多种炎性因子的产生，并进一步加剧高糖引起的炎症、氧化应激反应，破坏细胞间紧密连接，通过抑制吞噬相关受体的表达降低RPE细胞的吞噬能力，从而加速DR的进展并加重其病变程度。这些结果不仅为深入研究RPE细胞的免疫功能提供了科学证据，也为寻找DR新的治疗靶点提供了启示。