CD200胎盘间充质干细胞微泡microRNA对急性肺损伤的免疫调节作用

Acute Lung injury (ALI) remains a devastating syndrome caused by overwhelming inflammatory responses with a mortality rate over 50% in China. Recent studies demonstrated that MSCs exerted their biological functions of immunosuppression injury repair, mainly through the realease of microvesicles (MSC-MVs) that containing factors and genetic materials with various biological activities, including mRNAs and microRNAs (miRNAs). We have previously found that CD200 positive placenta-derived MSCs (CD200-P-MSCs) possessed stronger immunosuppressive potentials relative to the CD200 negative subset cells，and miRNAs are capable of reducing inflammatory responses by targeting toll-like receptor pathway. We thus propose that the CD200 and MV miRNAs of CD200-P-MSCs may lend the host cells with a strong immunosuppressive property. The overall goal of present proposal is to uncover and understand the underlying mechanisms of immunoregulatory roles of CD200 and MV miRNAs of CD200-P-MSCs.To this end, the profiles of immunoregulation related-mRNAs and -miRNAs in the MSC-MVs and P-MSC of different CD200 phenotypes and culture conditions will first be analyzed, followed by exploring the immunosuppressive roles of CD200 and MV miRNAs in pulmonary epithelial cells and a mouse ALI model. These studies will provide novel insights into the underlying mechanisms of strong immunosuppressive activity of CD200-P-MSCs, and provide preclinical data for developing a specific, effective and safe MSC-MV-based cell-free therapy for ALI and other diseases.

急性肺损伤(ALI)是一种由失控性炎性反应引起的灾害性综合征，在我国死亡率高达50%以上。最近研究发现间充质干细胞（MSCs）主要通过释放含mRNAs和miRNAs等生物活性物质的微泡发挥免疫抑制和组织损伤修复作用。我们研究发现CD200阳性细胞(CD200-P-MSCs)较CD200阴性细胞有更强的免疫抑制功能，而miRNAs可以通过靶向调控Toll样受体信号途径抑制炎症反应。由此我们推测CD200-P-MSCs可能通过CD200和微泡miRNAs发挥其高效免疫抑制功能。本项目将在分析CD200-MSCs微泡miRNAs谱的基础上，研究CD200和微泡miRNAs抑制肺脏上皮细胞和ALI炎症反应中的作用机理，从而明晰CD200-P-MSCs CD200和微泡miRNAs的免疫抑制作用机制。项目的实施将为基于MSC-MVs开展特异、高效和安全的无细胞治疗ALI和其他疾病的研究提供理论依据。

间充质干细胞（MSC）可通过释放包裹有miRNAs的外泌体发挥其免疫抑制和组织损伤修复作用。在前期研究发现的CD200阳性细胞胎盘MSC (CD200-hfPMSC)较CD200阴性细胞有更强的免疫调节功能，和miRNAs通过靶向调控Toll-样受体(TLR)信号抑制炎症反应的基础上，本项目分析了不同CD200表型MSC-MVs的免疫调控相关的转录和miRNA谱，探讨CD200人胎盘胎儿侧间充质干细胞（CD200-hfPMSCs）及其上清的抗氧化能力，及其对肺脏上皮细胞和血管内皮细胞的氧化损伤的保护和修复作用和免疫调节作用与机制，并进一步探索了人胎盘胎儿侧间充质干细胞减轻小鼠肺脏急性损伤(ALI)和博来霉素诱导肺脏纤维化的的作用与机制，获得了如下4个方面的研究结果：1）发现人胎盘胎儿侧间充质干细胞（hfpMSCs）及其上清对肺脏上皮细胞抗氧化损伤的保护与修复作用，其机制是通过抑制凋亡相关蛋白的表达和激活Nrf2/Keap1/ARE抗氧化信号通路保护肺脏细胞氧化损伤；2）转录组学分析CD200胎盘胎儿侧间充质干细胞外泌体microRNA谱发现不同CD200表型的间充质干细胞亚型分泌的外泌体内miRNA存在差异；并且这些差异miRNA与免疫调节相关；3）hfPMSCs能够有效抑制LPS诱导的ALI小鼠肺部炎性因子的表达，改善肺血管通透性，抑制肺部水肿，而CD200-hfPMSCs可通过TLR4信号通路对LPS诱导的血管内皮细胞损伤起到抵抗炎性反应和抑制血管内皮细胞凋亡作用,并初步揭示hfPMSCs旁分泌肝细胞生长因子(HGF)调控LPS诱导的肺血管内皮细胞损伤的作用机制。4） 揭示hfPMSCs通过抑制MyD88信号介导的炎性反应减轻博来霉素诱导的小鼠肺脏纤维化，MyD88的缺失可减轻博来霉素诱导小鼠的肺部炎症和纤维化。这些工作为进一步研究人胎盘胎儿侧间充质干细胞的临床应用研究提供了理论依据。