MSCs释放的外泌体通过MiR-20a调节Treg细胞参与SLE的机制研究

Previous studies revealed that BM-MSCs from SLE patients displayed senescent characteristics and played an important role in immune dysregulation of Treg cells. Reversing BM-MSC senescence could restore their immunomodulatory capacity. Recently, exosomes have been recognized as an important mode of intracellular communication. In the preliminary experiments, we discovered that the expression of several miRNAs including miR-20a in exosomes of BM-MSCs from SLE patients were abnormally low. In addition, it was postulated that AKT could be one of the targets of miR-20a. We hypothesize that BM-MSCs from SLE patients release abnormal exosomes, in which the expression of miR-20a is decreased; and binding of miR-20a to PI3K/AKT/mTOR leads to aberrant Treg cells activation. To test our hypothesis, we will conduct the following experiments: 1) We will study the effect of exosomes from BM-MSCs of SLE patients on Treg cells regulation. 2) we will analyze the effect of miR-20a on Treg cell activation. 3) Finally, we will attest the effect of miR-20a in the MRL/lpr mice. This project will further our understanding on the mechanism of SLE BM-MSCs abnormality and provide the theoretical basis to seek new diagnosis and treatments of SLE.

前期研究发现SLE患者BM-MSCs呈现衰老征象，调节Treg细胞能力下降。干预BM-MSCs的衰老可改善其免疫调节功能。外泌体可通过旁分泌的方式进行细胞间信息交流。预实验发现SLE患者BM-MSCs的外泌体中包括miR-20a在内的多种miRNA表达异常，且生物信息学方法预测提示AKT可作为miR-20a的靶基因。据此提出在SLE发展过程中，BM-MSCs释放的外泌体内容物存在异常，其中miR-20a表达下调，通过PI3K/AKT/mTOR信号通路调节Treg细胞功能的假说。课题组将明确BM-MSCs释放的外泌体对Treg细胞的影响，探讨外泌体中miR-20a对Treg细胞的影响及其中的机制，并在SLE动物模型中进行验证。此研究将进一步阐明衰老的BM-MSCs免疫调控失调的分子机制，为SLE治疗的新的靶点提供理论依据和数据支持。

系统性红斑狼疮（SLE）是一种累及全身多系统的自身免疫性疾病。研究发现SLE患者BM-MSCs呈现衰老征象，调节Treg细胞能力下降。Exosomes是细胞间通讯的重要工具，exosomes的异常参与SLE发生发展过程。课题组首先分离并培养了正常人和SLE患者的BM-MSCs，提取培养并鉴定成功。同时，分离了BM-MSCs细胞上清中的exosomes，并鉴定成功。接着，我们将正常人和SLE患者BM-MSCs来源的exosomes分别与naïve CD4+T细胞在Treg分化条件下共培养，探讨SLE患者BM-MSCs释放的exosomes对Treg细胞的影响，流式验证正常BM-MSCs来源的exosomes可促进Treg分化而SLE患者exosomes的促进Treg分化的功能较差。我们进一步分析正常人和SLE患者BM-MSCs及其exosomes中miR-20a的表达差异，分析SLE患者BM-MSCs释放的exosomes中miR-20a对Treg细胞的影响。另外，我们还研究了SLE患者血小板减少与Treg及其细胞因子的相关性，发现SLE患者血小板计数、Treg细胞比例及其细胞因子IL-10和TGF-β均呈正相关。本研究表明SLE患者BM-MSCs释放的exosomes内容物存在异常，其中miR-20a表达下调，调节Treg细胞免疫调节功能异常。研究结果进一步阐明BM-MSCs免疫调控的分子机制，为SLE治疗的新的靶点提供理论依据和数据支持。