Separation of GVH and GVL Responses Using Alloreactive CD8 iTregs

造血细胞移植（HCT）可以治疗多种良恶性造血系统疾病， 疾病，但移植物抗宿主病（GVHD）仍然是移植相关疾病的主要原因 和死亡率，从而限制了同种异体HCT的治疗潜力。供体T细胞包括在 干细胞接种并识别广泛分布受体同种异体抗原引起GVHD，但这些T 干细胞还通过促进干细胞植入和介导移植物抗白血病（GVL）而有益 方面的影响.因此，选择性地抑制同种异体反应性T细胞是预防GVHD的理想方法。 对广泛表达的同种异体抗原具有特异性，同时保留具有其他特异性的T细胞。主导 由调节性T细胞（Tcells）介导的耐受机制在免疫治疗中具有明显的治疗意义。 防止GVHD。为了在临床HCT中应用THBE，目前的方法集中于THBE的过继转移。 在HCT之前或之后，将多克隆、离体扩增的TCR4给予移植受体。但这些 预期多克隆THBE在控制GVHD方面具有低效力，并提供非选择性的 免疫抑制，从而否定了GVH和GVL反应的分离。我们证明了抗原- 在临床前BMT中，特异性TcR在预防急性GVHD方面远远优于多克隆TcR 模型这些临床前研究提供了理论基础，以支持在测试宿主同种异体抗原的第一个临床试验 GVHD中的反应性T细胞。尽管宿主同种异体抗原反应性CD4 iT细胞在控制 GVHD，它们也可能损害GVL效应。虽然该项目是我们目前研究的连续体，但我们 将把我们的重点更多地转移到同种异体反应性CD8 iT细胞上，因为这是最近发现的Treg亚群， 因为它们有可能避免甚至增强GVL效应。我们的长期目标是利用 同种异体抗原反应性THBVDNA，以预防GVHD，同时保留人类HCT后的GVL效应。的 本提案的目的是测试有效和可翻译的策略，以实现这一目标，在临床前 同种异体BMT的鼠模型。正如我们的初步数据所有力支持的那样，我们假设， 在保持GVL活性的同时控制GVHD可以通过与同种异体移植物的联合治疗来实现， 反应性CD4和CD8 iT细胞，或通过稳定的CD8 iT细胞的单一疗法。我们计划测试 假设，并通过追求两个具体目标来实现目标：1）建立组合 用CD4和CD8免疫抑制剂治疗，以控制GVHD和肿瘤复发; 2）增强稳定性， 以及CD8 iT细胞在预防GVHD中的潜力。如果该项目的目标得以实现， 所获得的知识将改变验证和应用同种异体反应性CD8 iT细胞的范式， GVHD和白血病复发，这将最终使血液系统恶性肿瘤患者受益。

Hematopoietic cell transplantation (HCT) can cure a variety of benign and malignant hematopoietic disorders, but graft-versus-host disease (GVHD) remains the primary cause of transplant-related morbidity and mortality, thereby limiting the therapeutic potential of allogeneic HCT. Donor T cells that are included in the stem cell inoculums and recognize widely distributed recipient alloantigens cause GVHD, but these T cells are also beneficial by facilitating stem cell engraftment and mediating graft-versus-leukemia (GVL) effects. Therefore, an ideal approach to prevent GVHD is to selectively inactivate alloreactive T cells specific for broadly expressed alloantigens, while sparing T cells with other specificities. A dominant mechanism of tolerance mediated by regulatory T cells (Tregs) has obvious therapeutic implications in preventing GVHD. To apply Tregs in clinical HCT, current approaches are focused on adoptive transfer of polyclonal, ex vivo-expanded Tregs to transplant recipients, before or after the HCT. However, these polyclonal Tregs are expected to have a low potency in controlling GVHD and provide non-selective immune suppression thereby negating separation of GVH and GVL reactions. We demonstrate that antigen- specific Tregs are far superior to polyclonal Tregs in the prevention of acute GVHD in pre-clinical BMT models. These preclinical studies provide rationale to support the first clinical trial in testing host-alloantigen reactive Tregs in GVHD. Although host-alloantigen reactive CD4 iTregs are highly effective in controlling GVHD, they may impair the GVL effect as well. While the project is a continuum of our current research, we will shift our focus more on alloreactive CD8 iTregs, because this is Treg subset recently discovered and because they have the potential to spare or even enhance the GVL effect. Our long-term goal is to use alloantigen-reactive Tregs to prevent GVHD while preserving the GVL effect after HCT in humans. The objective of this proposal is to test effective and translatable strategies to achieve this goal in pre-clinical murine models of allogeneic BMT. As strongly supported by our preliminary data, we hypothesize that the control of GVHD while preserving the GVL activity can be achieved by a combinational therapy with allo- reactive CD4 and CD8 iTregs, or by a singular therapy with stabilized CD8 iTregs. We plan to test our hypothesis and accomplish the objective by pursuing two Specific Aims: 1) To establish the combinational therapy with CD4 and CD8 iTregs for the control of GVHD and tumor relapse; 2) To enhance the stability and potential of CD8 iTregs in the prevention of GVHD. If the aims of this project are achieved, the acquired knowledge will shift the paradigm in validating and applying alloreactive CD8 iTregs for controlling GVHD and leukemia relapse, which will eventually benefit patients with hematological malignancies.