Targeting T-cell costimulation and cytokine activation to prevent GVHD and preserve GVL

摘要 移植物抗宿主病(GVHD)是异基因造血术后无复发死亡的主要原因 细胞移植(AllHCT)。目前GVHD的预防依赖于广泛抑制的他克莫司 不能耐受捐献者T细胞的组合。他克莫司抑制T细胞受体(TCR)激活和损伤 调节性T细胞(Treg)的寿命和功能。测试的新方法不是针对TCR，而是 这种应用是同时阻断T细胞共刺激和细胞因子激活的一种策略，以备 Tregs，预防GVHD，并维持移植物抗白血病(GVL)。CD28共刺激T细胞需要 MTOR和Aurora激酶的信号转导，其中抑制任何一个分子都可以改善GVHD 啮齿动物。IL-6受体引导JAK2磷酸化STAT3，使致病Th1和Th17极化 发展超过了受益的树。我们观察到，在接受异基因HCT的患者中，STAT3活性增加 后来发展成急性移植物抗宿主病。阻断JAK2或STAT3也可减少小鼠移植物抗宿主病。我们的数据支持 双重抑制CD28和IL-6活性的概念是协同的，可以提供持久的GVHD预防 完好的GVL。此应用程序的目标1将在原则证明临床试验中通过将 帕利替尼联合西罗莫司免疫抑制分别靶向JAK2和mTOR信号转导通路 减少GVHD。目标2和目标3将测试下游信号分子的中和假设 在CD28和IL-6的指导下，将产生不同的免疫结果，并共同更完全地控制 捐献的T细胞。与JAK2不同，STAT3在分子上抵消了Treg的发育。我们提供证据证明 JAK2阻断允许自然Treg发育，而抑制STAT3则增加诱导性Treg(ITreg)。在……里面 目的2，我们将研究STAT3/mTOR抑制是否比JAK2/mTOR抑制在减少 通过促进iTreg分化诱导小鼠GVHD。我们提供的证据表明，对极光激酶的抑制 显著增强iTreg抑制效力。在目标3中，我们将确定是否以STAT3/Aurora为目标 在通过增加iTreg分化和功能来预防GVHD方面优于JAK2/Aurora。这些 实验将指导无他克莫司的GVHD预防方案的未来转化和开发。我们的 长期目标是开发选择性免疫抑制策略，有效预防GVHD和 维持维持GVL所需的基本T细胞反应。

ABSTRACT Graft-versus-host disease (GVHD) is a leading cause of non-relapse mortality after allogeneic hematopoietic cell transplantation (alloHCT). Current GVHD prophylaxis relies on broadly suppressive tacrolimus-based combinations that fail to tolerize donor T-cells. Tacrolimus inhibits T-cell receptor (TCR) activation and impairs regulatory T-cell (Treg) longevity and function. Rather than targeting the TCR, the novel approach tested in this application is concurrent blockade of T-cell costimulation and cytokine activation as a strategy to spare Tregs, prevent GVHD, and maintain graft-versus-leukemia (GVL). CD28 costimulation of T-cells requires signal transduction by mTOR and Aurora kinase, where inhibiting either molecule ameliorates GVHD in rodents. The IL-6 receptor directs JAK2 to phosphorylate STAT3, which polarizes pathogenic Th1 and Th17 development over beneficial Tregs. We observed that STAT3 activity is increased in alloHCT recipients who later develop acute GVHD. Blockade of JAK2 or STAT3 also reduces murine GVHD. Our data support the concept that dual inhibition of CD28 and IL-6 activity is synergistic and offers durable GVHD prevention with intact GVL. Aim 1 of this application will test this hypothesis in a proof-of-principle clinical trial by combing pacritinib with sirolimus-based immune suppression to respectively target JAK2 and mTOR signaling and reduce GVHD. Aims 2 and 3 will test the hypotheses that neutralization of downstream signaling molecules directed by CD28 and IL-6 will yield distinct immune outcomes and collectively more complete control over donor T-cells. Unlike JAK2, STAT3 molecularly counteracts Treg development. We provide evidence that JAK2 blockade permits natural Treg development, while STAT3 inhibition increases inducible Tregs (iTreg). In Aim 2, we will investigate whether STAT3/mTOR inhibition is better than JAK2/mTOR inhibition in reducing GVHD in mice by enhancing iTreg differentiation. We provide evidence that inhibition of Aurora kinase significantly increases iTreg suppressive potency. In Aim 3, we will determine whether targeting STAT3/Aurora is better than JAK2/Aurora to prevent GVHD by increasing both iTreg differentiation and function. These experiments will direct future translation and development of tacrolimus-free GVHD prophylaxis regimens. Our long-term goal is to develop selective immune suppression strategies that effectively prevent GVHD and maintain essential T-cell responses needed to preserve GVL.