血管内皮细胞来源外泌体介导LncRNA TUG1调控IL-18诱导血管钙化的机制研究

Vascular calcification predicts increased risk of cardiovascular events. However, the mechanism of vascular calcification is not yet clear. Vascular calcification is a process similar to bone and cartilage formation. Our previous study found that IL-18 induces the calcification of vascular smooth muscle cells (VSMCs) and their transformation to osteogenic phenotypes. In addition, exosomes have been shown to be involved in the regulation of vascular calcification, and inflammatory cytokines can promote the release of exosomes. Signal transduction between vascular endothelial cells (VEC) and VSMCs is a key link in the formation of vascular calcification. Exosomes are considered to be important carriers of signaling molecules between VEC and VSMCs. In addition, exosomes also mediate the biological effects of LncRNA. LnRNA TUG1 is involved in the regulation of osteoblastic phenotype transformation of cells. Our preliminary experiments showed that IL-18 can significantly up-regulate the expression of LncRNA TUG1 in VEC exosomes. At the same time, studies reported that the Wnt/β-catenin pathway is an important regulatory pathway for vascular calcification and LncRNA TUG1. Therefore, this study proposes a scientific issue in which VEC exosome-mediated LncRNA TUG1 participates in the regulation of IL-18-induced vascular calcification through the Wnt/β-catenin signaling pathway. We will inhibit and overexpress LncRNA TUG1 in VEC, respectively. And then exosomes are extracted to intervene in IL-18-induced vascular calcification in vivo and in vitro. In addition, we will detect the effects of Wnt/β-catenin pathway blockers on this process. This study will deeply analyze the rule of IL-18-VEC exosomes-LncRNA TUG1 -Wnt/β-catenin-vascular calcification, and provide more ideas for finding effective intervention for inflammation-induced vascular calcification.

血管钙化是心血管病患病率增加的重要预测指标，目前缺乏有效的防治措施。我们的研究发现IL-18可诱导血管平滑肌细胞（VSMCs）钙化。外泌体参与调控血管钙化形成，炎症因子可促进外泌体释放。外泌体是血管内皮细胞（VEC）和VSMCs间信号传递的载体。外泌体还介导LncRNA的生物学效应，LnRNA TUG1参与调控细胞向成骨表型转化，我们的预实验发现IL-18可以上调VEC外泌体中LncRNA TUG1表达。同时，Wnt/β-catenin 通路是血管钙化和LncRNA TUG1发挥生物学效应的调控通路。因此，本研究提出了VEC外泌体介导的LncRNA TUG1通过Wnt/β-catenin信号通路参与调控IL-18诱导血管钙化的过程这一科学问题。我们通过在体和体外实验验证调控LncRNA TUG1表达的VEC外泌体是否可抑制IL-18诱导的血管钙化，为寻找干预炎症诱导的血管钙化提供更多思路。

血管钙化是慢性肾衰竭患者心血管疾病发病率和患者死亡率增加的重要预测因子。众所周知，肥胖和代谢综合征是慢性肾衰竭患者预后不良的重要影响因素，但肥胖和代谢综合征对慢性肾衰竭患者血管钙化发生发展的影响尚不清楚。IL-18介导了肥胖和代谢综合征相关的炎症反应，但IL-18是否参与慢性肾衰竭患者中肥胖和代谢综合征诱导的血管钙化目前还没有相关研究。本研究探讨了高脂饮食引起的肥胖和代谢综合征是否会影响慢性肾衰竭大鼠血清IL-18水平，加重血管钙化的程度，同时还进一步探讨了IL-18是否通过激活MAPK通路诱导大鼠血管平滑肌细胞钙化。研究结果发现慢性肾衰竭组和喂养了高脂饮食的慢性肾衰竭组大鼠的主动脉钙含量及BMP-2表达均较假手术组明显升高。喂养了高脂饮食的慢性肾衰竭组大鼠主动脉钙含量及BMP-2表达明显高于慢性肾衰竭组。而且大鼠血清IL-18水平与主动脉钙含量呈正相关。研究还发现p38抑制剂可以抑制IL-18诱导的大鼠血管平滑肌细胞钙化和向成骨细胞表型分化。本研究结果提示高脂饮食诱导的肥胖相关炎症可加重慢性肾衰竭大鼠血管钙化的程度。此外，IL-18通过激活p38通路促进大鼠血管平滑肌细胞向成骨表型转分化和钙化。