miR-181a和miR-150调节树突状细胞参与的炎症免疫反应在梗死后心室重构中作用的研究

Activation of the immune inflammation plays an important role during the process of ischemic cardiac injury and remodeling, which includes the production and release of proinflammatory cytokines such as tumor necrosis factor-α (TNF-α),activation of the complement system, production of auto-antibodies, and over-expression of class II major histocompatibility complex molecules. Dendritic cells (DC) initiate the immune inflammation response, but the regulatory function of DC is unclear till now. MicroRNAs (miRNAs) are critical for DC functions, and furthermore, miRNAs are involved in ischemic cardiac injury and anti-injury process. We have found that miR-181a and miR-378 promote the regulatory DC and additionally, these two genes are involved in cardiac remodeling process. Therefore, we put forward the hypothesis that miR-181a/150 promote the modulatory DC, as as to attenuate the ischemic cardiac injury and heart functions. To illuminate this point, firstly, we want to demonstrate the negative regulatory functions and the mechanisms of miR-181a/378 to DC as well as their roles in the ischemic cardiac injury; then, we try to clarify the functions of miRNAs on DC to the ischemic heart, based on the following animal models, myocardial infarction mice, the conditionally knock-in mice of miR-181a/150 in DCs, and the DC-depletion mice (CD11c-DTR); finally, we want to clarify the clinical significance of miRNA on DC function in myocardial infarction patients. In summary, through this project, we try to illuminate a novel epigenetic mechanism in ischemic cardiac injury and anti-injury process mediated by miRNA-induced DC modulation functions. And we also want to demonstrate the great significance of this mechanism so as to improve the clinical management of the ischemic cardiac injury patients.

炎症免疫反应是心肌损伤后心室重构的关键机制。树突状细胞（DC）是免疫应答启动、调控和维持的重要环节，最近研究发现DC与急性心肌梗死（AMI）后心肌损伤和重构密切相关，但机制不清。本项目从心肌损伤与DC免疫炎症基因表达失控的中间环节- - miRNAs着手，在既往研究基础上，一方面通过体外实验，确立miR-150 和miR-181a对DC免疫功能成熟的影响及对心肌损伤和重构的作用及机制；另一方面通过动物实验，构建条件性DC过表达miRNA小鼠的心梗模型，同时利用CD11c-DTR小鼠建立DC缺失小鼠心梗模型，确立miRNA调节DC参与的炎症免疫反应在心肌损伤和重构中效应与机制；最后通过AMI患者循环miRNA 及DC水平及功能研究，探讨其在心肌损伤与重构中的临床意义。通过本研究，揭示miRNA 调控的DC在AMI心室重构中的关键作用，并进一步拓展其表观遗传调控机制。

miRNAs通过精细调控炎症免疫因子基因表达从而和心肌损伤与重构密切相关，而DCs则通过启动炎症免疫反应、参与心肌缺血损伤与重构过程，但miRNAs如何通过调节DCs参与炎症免疫从而在梗死后心室重构发挥作用尚不清楚。本项目研究主要负责以下内容并已取得研究结果：（1）体外研究miRNAs对DCs免疫功能的影响及在心肌损伤与重构中的作用，发现坏死心肌上清可激活DCs的JAK/STAT通路并促进c-Fos和NF-κB p65的核转位，而通过抑制这一过程可抑制DCs免疫成熟，故这一通路的激活过程是促使DCs免疫成熟、进而促进缺氧时心肌细胞凋亡的关键通路之一；但过表达miR-181a或miR-150后JAK/STAT通路被抑制，继而也抑制了DCs免疫成熟，说明了miR-181a和miR-150可能通过抑制JAK/STAT通路进而抑制DCs免疫成熟功能、参与其促进心肌损伤重构过程中的负调节。（2）在体研究miRNAs调控DCs及心肌损伤与重构的作用及机制，发现缺血后适应可减轻梗死面积、改善心肌凋亡相关指标，进而有助于改善心肌缺血再灌注损伤后的心室重构，但这一心脏保护作用被miR-499敲低所抑制，因此验证了miR-499可能通过抑制PDCD4成为缺血后适应保护效应的关键因素。（3）研究临床AMI患者外周血miRNAs及DCs水平与功能，探讨在心肌损伤重构中的临床意义，发现AMI组miR-181a明显高于UA组及健康对照组，而AMI组的miR-181a水平和心肌损伤标志物如CK-MB、cTnI浓度、冠脉Gensini评分正相关，而和LVEF呈负相关，即miR-181a呈现出和急性冠脉病变严重程度、梗死严重程度正相关的趋势，并且ROC曲线分析表明miR-181a对AMI的诊断价值很高。我们的研究表明，miR-181a和miR-150通过调节DCs参与炎症免疫反应从而发挥促进心肌损伤重构的作用，而miR-499则参与了缺血后适应保护作用的分子机制，DCs炎症免疫相关的miRNA还可作为临床急性心肌梗死的新型诊断标志物。我们较好地完成了预期计划研究内容，发表了SCI论文各三篇。