CD47-SIRPalpha Signaling in Mesenchymal Stem Cell-Mediated Immune Regulation in Liver Transplant Inflammatory Injury

项目摘要 缺血再灌注损伤（IRI）诱导的先天性免疫驱动的局部炎症反应导致肝脏缺血再灌注损伤（IRI）。 肝移植后的功能障碍和衰竭。间充质干细胞（MSC）提供了新的 深入了解其潜在的临床应用，特别是用于治疗各种免疫介导的疾病。 先前的研究表明，MSC和炎症细胞之间的串扰在机制中至关重要 MSC介导的免疫调节和组织修复。事实上，基于MSC的治疗已经成功地 应用于各种人类疾病。然而，MSC免疫疗法的多项临床III期试验失败 因为移植细胞的低功效，因此，增加 通过探索新免疫调节机制来研究MSC的免疫抑制特性， MSC治疗的关键挑战。CD 47（整合素相关蛋白，IAP）是细胞表面蛋白， 几乎所有的细胞都能表达。造血干细胞（HSC）中CD 47表达增加 在动员或诱导炎症后。CD 47的连接可以诱导细胞内信号传导，导致细胞凋亡。 分化和激活响应压力。通过与细胞表面糖蛋白结合，信号调节 蛋白α（SIRPα）是一种存在于骨髓细胞上的抑制性跨膜受体，CD 47可以调节细胞增殖， 在单核细胞/巨噬细胞谱系中起作用。事实上，SIRPα在巨噬细胞中大量表达， 在炎症反应期间参与调节先天免疫。SIRPα缺乏增强 巨噬细胞NF-κB活化和促炎介质增加，这表明SIRPα是一种重要的 先天免疫的内源性调节剂。先前的一项研究表明，Notch 1信号调节 巨噬细胞功能和TLR 4/NF-κ B驱动的炎症反应。它还 Notch 1信号传导加剧了原位肝移植中的肝细胞损伤 (OLT)在人类身上。因此，CD 47/SIRPα和Notch 1通路可能在MSC介导的细胞凋亡中起重要作用。 奥尔特中先天免疫应答的调节。本提案的总体目标是剖析 细胞内CD 47/SIRPα信号在MSC介导免疫调节和增强MSC治疗中作用 通过在小鼠奥尔特中遗传修饰CD 47/SIRPα的功效。假设CD 47/SIRPα信号通路 通过激活MSC中的Notch-Hes 1轴来控制奥尔特接受者中TLR 4驱动的炎症。 介导的免疫调节。为了验证这一假设，提出了以下具体目标：1）分析 CD 47-SIRPα相互作用在调节MSC介导的TLR 4驱动的炎症反应中的作用 体外免疫调节实验; 2）体内研究CD 47修饰的MSC的免疫调节能力。 这些研究将增加对CD 47/SIRPα介导的MSC介导的调控网络的理解。 免疫疗法事实上，MSC的遗传修饰以提高治疗效果可能被证明是至关重要的 重要性，有效地针对IR应激受体的实体器官移植。

PROJECT SUMMARY Innate immune-driven local inflammation response induced by ischemia-reperfusion injury (IRI) causes hepatic dysfunction and failure following liver transplantation. Mesenchymal stem cells (MSCs) has provided new insights into their potential clinical application, particularly for treating a variety of immune-mediated diseases. Previous studies have shown that crosstalk between MSCs and inflammatory cells is crucial in the mechanism of MSC-mediated immune modulation and tissue repair. Indeed, MSC-based therapy has been successfully applied in various human diseases. However, a number of clinical phase III trials of MSC immunotherapy failed to meet the primary endpoints because of the low efficacy of engrafted cells. Thus, increasing the immunosuppressive property of MSC by exploring novel immunoregulatory mechanisms emerges as one of the key challenges of MSC therapy. CD47 (integrin-associated protein, IAP) is a cell surface protein and expressed by virtually all cells in the body. CD47 expression is increased in hematopoietic stem cells (HSCs) after mobilization or induced inflammation. Ligation of CD47 can induce intracellular signaling resulting in cell differentiation and activation in response to stress. By binding to the cell surface glycoprotein, signal regulatory protein alpha (SIRPα), an inhibitory transmembrane receptor present on myeloid cells, CD47 can regulate cell function in the monocyte/macrophage lineage. Indeed, SIRPα is abundantly expressed in macrophages and has been implicated in regulating innate immunity during inflammatory response. SIRPα deficiency enhanced macrophage NF-κB activation and increased pro-inflammatory mediators, implying that SIRPα is an essential endogenous regulator of the innate immunity. A previous study has shown that Notch1 signaling regulates macrophage function and TLR4/NF-κB-driven inflammatory responses in IR-stressed mouse livers. It has also documented that Notch1 signaling alleviates the hepatocellular damage in orthotopic liver transplantation (OLT) in humans. Thus, CD47/SIRPα and Notch1 pathways are likely essential in the MSC-mediated regulation of innate immune responses in OLT. The overall goal of this proposal is to dissect the function of intracellular CD47/SIRPα signaling in MSC-mediated immune regulation and enhance MSC therapeutic efficacy by genetically modifying CD47/SIRPα in murine OLT. The hypothesis is that CD47/SIRPα signaling controls TLR4-driven inflammation in OLT recipients through activation of the Notch-Hes1 axis in MSC- mediated immune regulation. To test this hypothesis, the following specific aims are proposed: 1) Analyze the role of the CD47-SIRPα interaction in regulating TLR4-driven inflammatory response in MSC-mediated immune regulation in vitro; 2) Investigate the ability of immune regulation by CD47-modified MSC in vivo. These studies will increase understanding of CD47/SIRPα-mediated regulatory networks in MSC-mediated immunotherapy. Indeed, genetic modification of MSC to improve therapeutic efficacy may prove of paramount importance to effectively target IR stress in recipients of solid organ transplants.