TNFSF15介导小胶质细胞M1/M2型极化治疗DR的作用和机制研究

Microglial activation and M1/M2 polarization mediated microvasculopathy and neurodegeneration plays a key role in the pathogenesis of diabetic retinopathy. Regulation of microglia has been demonstrated a new target for the treatment of DR. TNFSF15 is an endogenous neovascularization inhibitor, and mediates inflammation and expression of microRNA through death receptor 3 (DR3). Our pre-experiment found that TNFSF15 decreased the number of activated microglia, and down regulated VEGF expression in DR rat model, and alleviated BRB permeability, and increased miR-124 expression as well. However, the mechanism of TNFSF15 action on DR is unclear. In this project, we will investigate 1) if TNFSF15 protects BRB integrity and neuron damage through inhibiting microglia activation and promoting M2 polarization in DR; 2) to elucidate the role of miR-124 in TNFSF15/DR3 inhibited microglia activation and triggered M2 polarization. This study will reveal the mechanism of how TNFSF15 regulates the microglia in retina, and provide a new therapeutic strategy for the treatment of DR.

小胶质细胞活化和M1/M2型极化介导的视网膜微血管病变和神经变性在糖尿病视网膜病变（DR）发病机制中发挥重要作用，调控小胶质细胞的活化及极化是治疗DR的新靶点。TNFSF15作为重要的血管内皮负性调控因子，通过作用于死亡受体3(DR3)激活下游通路，发挥调节炎症反应和调控小分子RNA等生物学效应。课题组前期研究发现，TNFSF15过表达可减少DR大鼠视网膜组织内活化的小胶质细胞数量、VEGF表达和血视网膜屏障（BRB）渗漏，同时伴miR-124表达明显升高，但机制不详。本课题将进一步探索：1）在DR中，TNFSF15是否通过调控小胶质细胞活化和M1/M2型极化来保护BRB和神经节细胞；2）探索TNFSF15/DR3是否通过上调miR-124，从而抑制小胶质细胞活化、促进其M2型极化。进一步明确TNFSF15在调控小胶质细胞中的作用机制，为DR的防治提供新思路。

随着糖尿病患者数量激增，其重要的并发症之一糖尿病视网膜病变（DR）患者数量也逐年增加，已经成为成年人致盲的首要危险因素之一。DR小鼠模型中，小胶质细胞活化并发生迁移，Iba-1表达增高，M1型标记物表达增加，M2型标记物表达降低，miR-124表达降低。上调眼内TNFSF15水平，视网膜组织Iba-1表达降低，M1型标记物表达降低，M2型标记物表达增高，DR3及miR-124表达增高，紧密连接蛋白表达增加，BRB渗漏降低，神经节细胞数量增加；体外实验通过CRISPR/Cas-9敲除或过表达小胶质细胞miR-124，与TNFSF15处理的HRMEC细胞共培养，过表达miR-124后，HRMEC细胞通透性降低，降低小胶质细胞过度活化，M1型极化表达产物降低，M2型极化表达产物增加。本研究初步确定TNFSF15能够通过上调miR-124，抑制小胶质细胞的活性及M1极化，促进M2极化，降低BRB通透性，保护视网膜神经节细胞，最终缓解DR引发的微血管病变和神经变性。在本研究支持下发表SCI文章共4篇（见附件）。