Role of CD47 in xenograft rejection by macrophages

CD47 在巨噬细胞异种移植排斥中的作用

• 批准号: 7373273
• 负责人: YONG-GUANG YANG
• 金额: $ 32.79万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-12-01 至 2011-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7373273
• 关键词: Affect; Allografting; Antibodies; Attenuated; Binding; CD47 gene; Cell Line; Cells; Chimeric Proteins; Chimerism; Clinical Trials; Complement; Cytolysis; Data; Dendritic Cells; Dendritic cell activation; Development; Engraftment; Extracellular Domain; FUS-1 Protein; Failure; Family suidae; Future; Genetic; Goals; Hematopoietic; Human; Immune; Immune response; Immunosuppression; Immunosuppressive Agents; Investigation; Lead; Ligands; Mediating; Membrane; Modeling; Molecular; Mus; Natural Killer Cells; Organ; Organ Donor; Phagocytes; Phagocytosis; Play; Predisposition; Role; SHPS-1 protein; Signal Transduction; Source; Species Specificity; Stem cells; Sus scrofa; T-Lymphocyte; Testing; Therapeutic immunosuppression; Transfusion; Transgenic Mice; Transgenic Organisms; Transplantation; Treatment Protocols; Xenograft procedure; base; cytokine; improved; insight; macrophage; mouse model; nonhuman primate; prevent; receptor; response; stem; transgene expression

DESCRIPTION (provided by applicant): Xenotransplantation using pigs as the transplant source has the potential to resolve the growing shortage of human organ donors. The most profound barrier to xenotransplantation is the immunological rejection of the xenograft and the development of relatively non-toxic immunosuppressive or tolerance-inducting regimens is required to justify clinical trials of pig organs. CD47 is ubiquitously expressed and serves as a ligand of signal regulatory protein (SIRP)1, a key inhibitory receptor on phagocytes and APCs. Our pilot data have shown that: 1) pig CD47 cannot functionally interact with mouse or human SIRP1 and the expression of host- type CD47 on a pig hematopoietic cell line markedly inhibits its phagocytosis by xenogeneic (mouse or human) macrophages; 2) induction of mixed chimerism neither overcomes the CD47 barrier nor prevents rejection of pig hematopoietic cells by phagocytes; and 3) CD47-SIRP1 interaction is required for preventing host DC activation and inhibiting anti-donor T cell responses in mice after donor specific transfusion (DST). Based on these and other pilot data described in this application, we hypothesize that CD47 incompatibility makes xenogeneic hematopoietic cells highly susceptible to phagocytosis and augments T cell xenoreactivity by promoting APC activation; thus posing a strong barrier to xenotolerance induction by the mixed chimerism and DST approaches. To test our hypothesis, we will pursue three specific aims. Aim 1 is to evaluate the potential of CD47 transgene expression to inhibit phagocytosis of pig hematopoietic stem/progenitor cells (HSC/HPC). We will determine 1) whether mouse CD47-expressing pig HSC/HPC show reduced susceptibility to phagocytosis and improved ability to engraft in pig cytokine transgenic mice; and 2) if human CD47 expression can protect pig HSC/HPC from phagocytosis by human macrophages. In Aim 2, we will further characterize the interaction of pig CD47 with human SIRP1 (binding vs. function). We will determine: 1) if fusion proteins of pig CD47 extracellular domain can bind to human macrophage SIRP1; 2) the ability of pig CD47 to bind and signal through human SIRP1 at the cellular level; and 3) the possible role of CD47 MMS (multiply membrane-spanning) domain in determining the species specificity. In Aim 3, we will use CD47 KO mouse models to further understand how CD47-SIRP1 signaling contributes to DST-induced immunosuppression. We will determine whether the engagement of CD47 on DST donor cells with SIRP1 on recipient DCs can promote the induction of regulatory T cells by inhibiting DC activation/maturation, and if CD47 expression on donor cells is critical for the synergistic effect of DST with costimulatory blockade on tolerance induction. These studies are expected to provide insights into the mechanisms of xenoimmune responses, help in evaluating the value of making human CD47 transgenic pigs for improving xenotolerance induction by mixed chimerism and DST, and enlighten future investigations on the potential roles of other immune inhibitory receptors in xenograft rejection and xenoimmune tolerance.

描述（由申请人提供）：使用猪作为移植源的异种移植有可能解决人体器官捐献者日益增长的短缺。异种移植的最深刻障碍是异种移植物的免疫学排斥和相对无毒的免疫抑制或耐受性诱导方案的发展以证明猪器官的临床试验是合理的。 CD47无处不在，并用作信号调节蛋白（SIRP）1的配体，这是吞噬细胞和APC上的关键抑制受体。我们的试点数据表明：1）PIG CD47不能在功能上与小鼠或人类SIRP1相互作用，并且在猪造血细胞系上的宿主型CD47表达显着抑制了通过异种（小鼠或人）巨噬细胞的吞噬作用。 2）混合嵌合体的诱导既不克服CD47屏障，也不会阻止吞噬细胞对猪造血细胞排斥； 3）CD47-SIRP1相互作用是防止宿主DC激活并抑制供体特异性输血（DST）后小鼠中抗抑制T细胞反应的需要的。基于本应用程序中描述的这些和其他试验数据，我们假设CD47不相容性使异类造血细胞高度易受吞噬作用，并通过促进APC激活来增强T细胞异种反应性。因此，通过混合的嵌合和DST方法构成了异种耐体诱导的强烈障碍。 为了检验我们的假设，我们将追求三个具体目标。目的1是评估CD47转基因表达对抑制猪造血干/祖细胞（HSC/HPC）的吞噬作用的潜力。我们将确定1）表达小鼠CD47的猪HSC/HPC是否显示出对吞噬作用的敏感性降低，并提高了在猪细胞因子转基因小鼠中植入的能力； 2）如果人CD47表达可以保护猪HSC/HPC免受人类巨噬细胞的吞噬作用。在AIM 2中，我们将进一步表征PIG CD47与人类SiRP1（结合与功能）的相互作用。我们将确定：1）如果猪CD47的融合蛋白可以与人类巨噬细胞SIRP1结合； 2）PIG CD47在细胞水平上通过人类SIRP1结合和信号的能力； 3）CD47 MM（跨膜跨膜）结构域在确定物种特异性中的可能作用。 在AIM 3中，我们将使用CD47 KO小鼠模型进一步了解CD47-SIRP1信号如何有助于DST诱导的免疫抑制。我们将确定CD47对DST供体细胞与SIRP1在受体DC上的接合是否可以通过抑制DC激活/成熟来促进调节性T细胞的诱导，以及在供体细胞上的CD47表达是否对DST对DST的协同效应至关重要，而DST对DST具有对耐受性诱导的耐受性阻滞的效果。 预计这些研究将提供有关异种免疫反应机制的见解，有助于评估使人CD47转基因猪通过混合混合嵌合和DST提高异耐耐诱导的价值，并启发对其他免疫抑制受体在Xenogragnograptiment抑制和XenommMune耐受性中的潜在作用的未来研究。