Delta-like ligand 4+ dendritic cells and induction of alloimmunity

描述（由申请人提供）：异基因造血干细胞移植（allo-HSCT）是一种治疗多种对其他疗法耐药的血液恶性肿瘤的治愈性疗法。这种有益的抗肿瘤活性主要来源于输注的供体T细胞，称为移植物抗肿瘤（GVT）效应。然而，复发仍然是高危血液系统恶性肿瘤患者allo-HSCT治疗失败的主要原因。此外，GVT效应缺乏特异性，与移植物抗宿主病（GVHD）的危及生命的并发症密切相关。迫切需要新的方法来改善GVT，同时限制allo-HSCT后的GVHD。 Notch信号转导在外周T细胞应答中可能发挥多种重要作用。使用allo-HSCT的小鼠模型，我们发现：1）Notch剥夺的供体T细胞显示出产生效应细胞因子（例如，IFN-γ，TNF-α和IL-17），并未能引起GVHD，这表明Notch途径 在GVHD诱导期间，在受体树突状细胞（DC）的子集的表面上增加。我们将这些Dll 4阳性DC命名为Dll 4 + DC。与D114阴性DC（D114-DC）相比，D114 + DC表达更高水平的CD 80和CD 86，具有增加的IL 6和IL 23 mRNA，但减少的IL 12、IL 21和精氨酸酶1的转录。Dll 4的抑制引起同种异体DC激活的同种异体反应性效应T细胞的频率降低。此外，用抗Dll 4抗体（Ab）的体内处理抑制GVHD。因此，Dll 4激活Notch信号传导对于GVH应答是重要的; 3）Flt 3L和Toll样受体信号传导对于从培养的骨髓细胞诱导Dll 4 + DC是必需的。抑制NF-κB信号通路可阻断Flt 3 L诱导的DCs中Dll 4的表达; 4）Flt 3 L诱导的Dll 4 +DCs比GM-CSF诱导的Dll 4-DCs更能促进CD 4 + Th 1和Th 17细胞的分化。负载有肿瘤抗原肽的Flt 3L诱导的Dll 4 + DC的转移诱导了有效的CD 8 + T细胞介导的抗肿瘤活性。因此，我们假设D114 + DC是先前未表征的对于诱导GVHD和GVT重要的炎性DC。 提出了三个具体目标来确定这一假设。第一个目的是利用小鼠GVHD模型研究D114 +DCs的表型和功能特征及其在介导GVHD中的重要作用。第二个目的是定义调控Dll 4 + DC发育的机制。我们将研究STAT 3是否以及如何与NF-κB信号相互作用以控制DCs中Dll 4的表达。对D114 + DC发育的分子见解可能导致鉴定用于调节GVH应答的新靶标。最终的目的将是建立调节Dll 4 +DCs对改善allo-HSCT和白血病小鼠中GVT的有益作用。本研究的目的是设计一种新的治疗策略，以增加GVT，同时限制GVHD。 了解Dll 4 +DCs在同种免疫中的作用将导致开发新的和临床相关的方法来增强抗肿瘤免疫，这可能对每年接受allo-HSCT的约10，000名新患者有益。鉴于树突状细胞在获得性免疫中的核心作用，这些研究的结果可能在改善肿瘤免疫和控制其他炎症性疾病，如移植器官的移植物排斥反应和自身免疫性疾病方面具有重要意义。

DESCRIPTION (provided by applicant): Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative treatment for many hematological malignancies resistant to other therapies. This beneficial anti-tumor activity largely derives from infused donor T cells, named graft-versus-tumor (GVT) effect. However, relapse remains a major cause of treatment failure of allo-HSCT for patients with high-risk hematological malignancies. In addition, the GVT effect lacks specificity and is tightly linked to a life-threatening complication of graft-versus-host disease (GVHD). Novel approaches are urgently needed to improve GVT while limiting GVHD after allo-HSCT. Notch signaling may play multiple important roles in peripheral T cell responses. Using mouse models of allo-HSCT, we discovered that: 1) Notch-deprived donor T cells showed drastically reduced ability to produce effector cytokines (e.g., IFN-γ, TNF-α and IL-17) and failed to cause GVHD, suggesting that the Notch pathway increased on the surface of a subset of recipient dendritic cells (DCs) during GVHD induction. We named these Dll4-positive DCs as Dll4+DCs. As compared to Dll4-negative DCs (Dll4-DCs), Dll4+DCs expressed higher levels of CD80 and CD86, had increased IL6 and IL23 mRNA but reduced transcripts of IL12, IL21 and Arginase 1. Inhibition of Dll4 caused a reduction in frequency of alloreactive effector T cells activated by allogeneic DCs. Furthermore, in vivo treatment with anti-Dll4 antibody (Ab) inhibited GVHD. Thus, Dll4 activation of Notch signaling is important for GVH responses; 3) Flt3L and Toll-like receptor signaling were essential for induction of Dll4+DCs from cultured bone marrow cells. Inhibition of NF-κB signaling blocked the expression of Dll4 in Flt3L-induced DCs; 4) Flt3L-induced Dll4+DCs had greater ability than GM-CSF-induced Dll4-DCs to promote CD4+ T helper (Th)1 and Th17 cell differentiation. Transfer of Flt3L-induced Dll4+DCs that were loaded with tumor antigen-peptide induced potent CD8+ T cell-mediated antitumor activity. Thus, we hypothesize that Dll4+DCs are previously uncharacterized inflammatory DCs important for the induction of GVHD and GVT. Three specific aims are proposed to determine this hypothesis. In the first aim, we plan to use mouse GVHD models to identify the phenotypic and functional characteristics of Dll4+DCs and their important roles in mediating GVHD. The second aim is designed to define the mechanisms that regulate the development of Dll4+DCs. We will examine whether and how STAT3 interacts with NF-κB signaling to control the expression of Dll4 in DCs. Molecular insights into the development of Dll4+DCs may lead to the identification of novel targets for modulating GVH responses. The final aim will be to establish the beneficial effects of modulating Dll4+DCs on improving GVT in mice of allo-HSCT and leukemia. The goal of this aim is to design a new therapeutic strategy to augment GVT while limiting GVHD. Understanding the role of Dll4+DCs in alloimmunity will lead to the development of novel and clinically relevant approaches to augment antitumor immunity, which could be potentially beneficial to approximately 10,000 new patients who receive allo-HSCT every year. Given the central role of DCs in adaptive immunity, results from these studies may have significant implications in the improvement of tumor immunity and control of other inflammatory disorders such as graft-rejection of transplanted organs and autoimmune diseases in broad context.