Effects of PGE2 on reconstitution of hematopoiesis and immunity after UCBT

描述（由申请人提供）：脐带血移植（UCBT）的有利结局受到植入时间延长、免疫重建延迟和晚期记忆T细胞偏斜的影响。斑马鱼和小鼠的研究表明，短暂的离体前列腺素E2（PGE 2）暴露增加了HSC的数量，归巢和体内植入。我们进行了双UCBT（dUCBT）的Ib期临床试验，使用一个未处理的和一个体外PGE 2处理的UCB单位，以确定安全性和植入参数。我们证明了与历史对照组相比，骨髓移植的中位时间和PGE 2衍生的造血显著缩短。我们确定，短时间暴露于PGE 2诱导UCB T细胞和树突状细胞（DC）中b-连环蛋白的稳定。在UCB T细胞中，PGE 2通过EP 2/EP 4受体和cAMP介导的Gsk 3磷酸化修饰Wnt信号级联反应，从而稳定连环蛋白和TCF介导的转录。PGE 2诱导Wnt靶基因，包括Wnt途径的组分，但也包括Wnt受体，表明离体PGE 2处理引发T细胞体内Wnt/β-连环蛋白信号传导。已经证明小鼠中的Wnt/β-连环蛋白信号传导促进高效干细胞记忆CD 8 + T细胞的产生。与我们的假设一致，我们发现PGE 2-UCBT接受者中的T细胞显示出有限的体内扩增，CD 8+群体中CD 62+细胞分数的增加以及以转录因子TCF 7和EOMES的表达增加和KLRG的低水平为特征的中枢记忆样细胞的分子特征，所有这些都受Wnt信号转导的调节。此外，与对照dUCBT接受者相比，PGE 2-UCBT接受者具有改善的定量和定性胸腺重建，如通过TREC值和通过免疫SEQ测定所确定的。这些患者表现出有效的抗病毒免疫力，并降低了CMV和EBV病毒血症的发生率。这些结果在同种异体HSCT和特别是UCBT中特别重要，其中延迟的免疫重建的特征在于晚期记忆T细胞偏斜和胸腺功能的长期损害。我们的临床和实验室研究结果表明，PGE 2处理的HSC的移植优势可能允许在成年患者中使用单个UCB单位，并且PGE 2可能通过在体内启动Wnt介导的信号传导的免疫细胞来改变先天性和适应性免疫的重建。为了这些目的，我们将进行以下研究：1）确定单个离体PGE 2孵育的UCB单位移植的临床结果。2)检查UCB的离体PGE 2孵育对T细胞的分化、极化和功能的影响。3)检查UCB的离体PGE 2孵育对DC的分子和功能特性的影响。

DESCRIPTION (provided by applicant): The favorable outcome of umbilical cord blood transplantation (UCBT) is compromised by prolonged time to engraftment, delayed immunologic reconstitution and late memory T cell skewing. Zebrafish and mouse studies have shown that transient ex vivo prostaglandin E2 (PGE2) exposure increases HSC number, homing and engraftment in vivo. We performed a Phase Ib clinical trial of double UCBT (dUCBT), using one untreated and one ex vivo PGE2-treated UCB unit, to determine safety and engraftment parameters. We demonstrated a significant reduction in the median time to myeloid engraftment compared with historic controls, and PGE2- derived hematopoiesis. We determined, that short exposure to PGE2 induced stabilization of b-catenin in UCB T cells and dendritic cells (DCs). In UCB T cells PGE2 modified the Wnt signaling cascade through EP2/EP4 receptors and cAMP-mediated phosphorylation of Gsk3, resulting in stabilization of ¿-catenin and TCF-mediated transcription. PGE2 induced Wnt target genes, including components of the Wnt pathway but also Wnt receptors, suggesting that ex vivo PGE2 treatment primes T cells for Wnt/¿-catenin signaling in vivo. Wnt/¿-catenin signaling in mice has been demonstrated to promote the generation of highly potent stem cell memory CD8+ T cells. Consistent with our hypothesis, we found that T cells in PGE2-UCBT recipients displayed limited in vivo expansion, increase in CD62+ cell fraction in the CD8+ population and molecular features of central memory-like cells characterized by increased expression of transcription factors TCF7 and EOMES and low levels of KLRG, all of which are regulated by Wnt signaling. Furthermore, compared to control dUCBT recipients, PGE2-UCBT recipients had improved quantitative and qualitative thymic reconstitution as determined by TREC values and by immunoSEQ assay. These patients displayed potent antiviral immunity and reduced incidence of CMV and EBV viremia. These outcomes are of particular importance in allogeneic HSCT and specifically UCBT where delayed immune reconstitution is characterized by late memory T cell skewing and prolonged impairment of thymic function. Our clinical and laboratory findings suggest that the engrafting advantage of PGE2-treated HSC might allow for the use of a single UCB unit in adult patients, and that PGE2 might alter reconstitution of the innate and adaptive immunity by priming immune cells for Wnt mediated signaling in vivo. To these ends we will undertake the following studies to: 1) Determine the clinical outcome of single ex vivo PGE2 incubated UCB unit transplantation. 2) Examine the effect ex vivo PGE2 incubation of the UCB on the differentiation, polarization and function of T cells. 3) Examine the effects of ex vivo PGE2 incubation of the UCB on the molecular and functional properties of DC.