Enhancing Treg Therapeutic Efficacy in GVHD

描述（由申请方提供）：胸腺源性CD 4 +25+ FoxP 3+调节性T细胞（TCRs）是抑制自身免疫和限制外源抗原应答所必需的。我们的第一次在人体I期剂量递增试验的体外扩增的人TCLs证明有效地显着降低急性移植物抗宿主病（GVHD）的发病率。确定了均匀功效的两个主要限制：问题1（实现最佳抑制）：%抑制是可变的。问题2（维持足够的Treg：T效应子比率）：达到的1：5.5的比率远低于小鼠中GVHD预防所需的e1：1的期望比率;在转移后2周未检测到Treg。目标1将重点放在问题1上。PKC-q协调免疫功能，这导致其移动到T效应器中的免疫突触（T细胞和抗原呈递细胞之间的直接接触点），而不是T细胞。PKC-q缺陷型鼠T效应子不能引起GVHD，但可以保留抗肿瘤和抗病原体应答。用小分子PKC-q抑制剂处理的TcR具有增强的抑制功能，并且在抑制小鼠结肠炎中更有效。在目标1中，集中于问题1，我们将在体外或体内使用小分子PKC-q抑制剂来测试以下假设：鼠和人Treg抑制GVHD的效力受到PKC-q进入免疫突触的运动的限制。在目标2中，集中于问题2，我们将检验持续的IL-2 R信号传导途径将为Treg扩增和GVHD抑制提供PKC-q非依赖性途径的假设。我们将使用3种策略来改善Treg介导的GVHD抑制：（a）施用IL-2/抗-IL-2抗体复合物或低剂量IL-2以优先扩增鼠和人的T细胞相对于T效应子;（B）基于我们的发现，组成型STAT 5 b促进鼠Treg产生、增殖和功能，包括GVHD抑制，绕过对IL-2的需要，（c）在体外使用GSK-3b抑制剂增加b-连环蛋白信号传导，或 在人T细胞中表达稳定化的b-连环蛋白，因为稳定化的b-连环蛋白降低了Treg对IL-2的依赖性，并显著提高了鼠Treg存活率和预防结肠炎的功效。在目标3中，我们将从目标1和2中的研究中选择最佳的1-2种方法，用于在临床前GVHD模型中进行测试，以保留移植后的有益免疫应答。由于目标1和2开发的优选方法，不屈服于GVHD致死性的长期嵌合体将用白血病细胞或细菌或病毒病原体进行挑战，以量化免疫系统对移植后危及生命的并发症的反应程度。

DESCRIPTION (provided by applicant): Thymic-derived CD4+25+FoxP3+ regulatory T cells (Tregs) are required to suppress autoimmunity and limit foreign antigen responses. Our first-in-human phase I dose escalation trial of ex vivo expanded human Tregs proved efficacious in significantly reducing the incidence of acute graft-vs-host disease (GVHD). Two major limitations to uniform efficacy were identified: Problem 1 (achieving optimal suppression): The %suppression was variable. Problem 2 (maintaining adequate Treg:Teffector ratios): Ratios of 1:5.5 achieved were well below the desired ratios of e1:1 need for GVHD prevention in mice; no Tregs were detected by 2 weeks post-transfer. Aim 1 will focus on Problem 1. PKC-q coordinates immune function, which results in its movement to the immunological synapse (direct contact point between T cell and antigen-presenting cell) in Teffectors but not Tregs. PKC-q deficient murine Teffectors are unable to cause GVHD but can retain anti-tumor and anti- pathogen responses. Tregs treated with a small molecule PKC-q inhibitor had augmented suppressor function and were more effective in suppressing murine colitis. In aim 1, focused on Problem 1, we will use small molecule PKC-q inhibitors in vitro or in vivo to test the hypotheses that murine and human Treg potency for GVHD suppression is limited by movement of PKC-q into the immunological synapse. In aim 2, focused on Problem 2, we will test the hypothesis that sustained IL-2R signaling pathways will provide a PKC- q independent route to Treg expansion and GVHD suppression. We will use 3 strategies to improve Treg mediated GVHD suppression: (a) administer IL-2/anti-IL2 antibody complexes or low dose IL-2 to preferentially expand murine and human Tregs vs Teffectors; (b) Constitutively express STAT5b in murine and human Tregs based upon our findings that constitutive STAT5b promotes murine Treg generation, proliferation and function including GVHD suppression, bypassing the need for IL-2, present in limiting amounts in vivo; and (c) increase b-catenin signaling using a GSK-3b inhibitor in vitro or expressing a stabilized b-catenin in human Tregs since stabilized b-catenin reduces Treg dependency upon IL-2 and provides a marked enhancement of murine Treg survival and efficacy in preventing colitis. In aim 3, we will select the best 1-2 approaches, derived from studies in aims 1 and 2, for testing in preclinical GVHD models for the preservation of beneficial immune responses later post-transplant. Long-term chimeras that do not succumb to GVHD lethality, as a result of preferred approaches developed aims 1 and 2, will be challenged with leukemia cells or bacterial or viral pathogens to quantify the extent to which the immune system can respond to life-threatening complications post-transplant.