内皮微粒携带miR-155靶向调控T细胞蛋白异戊烯化在aGVHD/GVL平衡中的作用

It has become a major problem to look for a therapy to specifically alleviate aGVHD while not weaken GVL effect after allo-HSCT. Preliminary data indicated endothelial microparticles released by injuried endothelial cells play an important role in the setup and progress of aGVHD. However it remained elusive how functional endothelial microparticles are targeted involved in immune regulation during aGVHD. We recently found endothelial cells damage increased miR-155 expression carried by the endothelial microparticles significantly. miR-155 is recently found involved in immune inflammatory reactions. Target gene prediction software showed that protein prenylation modification is one of targeted pathways of miR-155. The latest researches showed that agents blocking protein prenylation possess both immunosuppression and antitumor effect. Therefore, we hypothesize that during the development of aGVHD, endothelial cells damage induce the release of endothelial microparticles which transfer information through their carried miR-155 to targeted regulate protein prenylation modifications of T cells. Inhibiting this pathway might alleviate aGVHD while not affect GVL effect. This project is proposed to prove the role of this pathway in aGVHD by a serial of in vivo and in vitro experiments. It would lay the foundation for clarifying new mechanism of pathogenesis of aGVHD and GVL, and seeking specific prediction index for aGVHD. In addition, it would provide new method for targeted therapy of aGVHD / GVL balance.

寻找一种特异性抑制aGVHD而不削弱GVL效应的方法是目前allo-HSCT领域亟待解决的难题。前期研究发现内皮细胞损伤后释放内皮微粒在aGVHD中发挥重要作用，但具有生物活性的内皮微粒如何靶向参与aGVHD中的免疫调控仍未阐明。我们最近发现内皮细胞损伤后内皮微粒上miR-155水平增高，miR-155也被证实参与免疫炎症反应，靶基因预测软件显示蛋白异戊烯化修饰是miR-155的靶通路之一，而异戊烯化阻断剂同时具有免疫抑制及抗肿瘤效应，因此提出假说: 内皮细胞损伤诱导内皮微粒释放，内皮微粒传递miR-155靶向调控T细胞蛋白异戊烯化参与aGVHD，阻断此通路可抑制aGVHD而不影响GVL效应。本项目拟通过体内外实验探索上述调控通路在aGVHD和GVL中的作用，这将为阐明aGVHD新的发病机制、寻找aGVHD特异性预测指标奠定基础，力争为aGVHD/GVL平衡的靶向治疗提供新的解决方案。

目前，造血干细胞移植术是治疗恶性血液病及其它血液系统非恶性疾病的有效手段，然而移植后急性移植物抗宿主病（aGVHD）是影响患者生存和预后的重要问题。有研究发现内皮微粒在aGVHD患者体内显著增高，但它的作用目前尚不清楚。我们发现，肿瘤坏死因子-α刺激诱导人脐静脉内皮细胞分泌的微粒携带过高浓度的micro-RNA-155（miR-155）。在aGVHD患者和小鼠外周血提取的微粒中，miR-155的水平显著高于血浆中miR-155水平，并且，微粒中miR-155升高的时间早于其在外周血T淋巴细胞中升高的时间。通过荧光示踪，我们发现，T淋巴细胞中升高的miR-155是由内皮微粒携带传递所致，而下调内皮微粒中miR-155水平并不能影响T淋巴细胞的增殖凋亡，但影响其分化发育。下调miR-155水平引起T淋巴细胞趋向TH1细胞，TH9细胞和TH17细胞分化，而抑制其向TH2细胞和Treg细胞分化，同时抑制T细胞异戊烯化水平。同样的，在小鼠aGVHD模型中，抑制miR-155的表达可以减轻其疾病严重程度，并影响小鼠外周血T淋巴细胞分化，减轻小鼠T细胞异戊烯化水平。这些研究成果表明内皮微粒携带的miR-155通过影响T细胞的分化发育及调节其异戊烯化参与aGVHD的发生与疾病进展，为其发病机制的研究提供新思路。