中性粒细胞弹性蛋白酶在糖尿病视网膜病变血管损伤中的作用

Neutrophils play a causal role in the early stage of diabetic retinopathy (DR) which is characterized by vascular lesion, however, the mechanism by which they cause such damage is unknown. Neutrophil elastase (NE) is a protease released by neutrophils and participates in a variety of inflammatory diseases. In the previous study, we found inhibition of NE reduce diabetes-induced retinal capillary degeneration and vascular leakage. Tight junction protein ZO-1, occludin, claudin-5, and TLR4-MyD88 signal pathway are closely associated with vascular leakage. Thus, we hypothesize that NE increases retinal vascular permeability in diabetes via degradation of tight junction protein or activation of TLR4 signal pathway to regulate the expression of inflammatory cytokines. Genetic deletion of NE or pharmacological inhibition of NE in diabetic animals will be conducted to investigate the effects of NE on the retinal vascular lesion in diabetes, to study if NE regulates endothelial cell permeability through its proteolytic activity to degrade tight junction proteins or active TLR4 signal in vitro. Understanding the role of NE in the development of DR could provide a novel therapy to inhibit DR.

中性粒细胞在早期糖尿病视网膜病变（DR）毛细血管损害中发挥重要作用，但其机制尚不清楚。中性粒细胞弹性蛋白酶（NE）是一种由中性粒细胞分泌并参与到一系列炎症性疾病中的蛋白酶。我们发现，抑制NE能降低糖尿病诱导的视网膜毛细血管退化和血管渗漏。紧密连接蛋白ZO-1、occludin、claudin-5 和TLR4-MyD88信号通路与糖尿病所致血管渗漏密切相关。据此提出假设：在糖尿病中，NE通过降解紧密连接蛋白，或激活TLR4-MyD88信号通路增加炎症因子表达使视网膜血管通透性增加。.本项目拟通过药物与基因敲除的方式抑制动物体内NE，观察其对糖尿病所致视网膜血管损害的影响，体外细胞实验研究NE是否通过其蛋白水解酶的活性降解紧密连接蛋白，或通过激活TLR4信号通路增加炎症因子表达来调节内皮细胞通透性。理解NE在DR发展过程中的分子机制，可为预防和治疗DR提供新的治疗方法。

中性粒细胞弹性蛋白酶（NE）是一种由中性粒细胞分泌并在糖尿病中升高的蛋白酶。但是它在糖尿病眼病（DR) 中的作用尚不清楚。本项目研究目的在于检测NE是否参与糖尿病导致的视网膜血管渗漏。通过研究我们发现通过基因敲除NE，可以降低血浆中NE水平并减缓小鼠因糖尿病（八个月）造成的视网膜血管渗漏。进一步研究法发现NE水平在IL-17基因敲除的小鼠中也有明显降低。并且在体外实验中，我们发现NE增加血管内皮细胞通透性是部分通过MyD88，NF-kB, PAR2 信号通路介导的，和降解VE-cadherin导致的。我们最终得出结论，IL-17可以调节NE在糖尿病中表达水平，同时NE导致的DR中血管内皮细胞渗透升高部分是受控于MyD88，NF-kB, PAR2 信号和VE-cadherin降解导致的。因此为未来治疗DR提供了潜在的治疗方向。