Transplantation tolerance and immune function following mTOR inhibition.

描述（由申请人提供）：非清髓性骨髓移植为镰状细胞性贫血等非恶性血液病提供了一种安全且具有潜在治愈性的治疗方法。不幸的是，由于免疫介导的移植排斥反应，成功的非清髓性移植治疗镰状细胞性贫血受到限制。我们的研究表明，雷帕霉素可以促进幼稚T细胞的调节性T细胞（Treg）分化和T细胞活化后Th1细胞的能量。我们利用这些观察结果开发了一种新的制备方案，通过促进T细胞耐受性来抑制排斥反应和移植物抗宿主病（GVHD）。我们的策略是使用阿仑妥珠单抗降低同种异体反应性T细胞的频率，为低剂量全身照射植入创造“空间”，并允许淋巴细胞在延长的雷帕霉素治疗下恢复。在匹配的兄弟姐妹中，这种方法取得了巨大的成功，导致稳定的混合嵌合，纠正了他们镰状细胞性贫血的血液学表型，并逆转了肺动脉高压。基于这一成功，我们开展了第二次临床试验，以扩大潜在的供体池，包括单倍体相同的相关供体，极大地增加了这种治疗对患者的潜在可用性。新的试验在选择预备方案时采用了相同的基本原则，并增加了移植后环磷酰胺的剂量，以进一步减少可能导致排斥或GVHD的同种异体反应性T细胞。在这项试验中，来自患者和供体的外周血样本将为系统地研究T细胞耐受性在促进稳定嵌合中的作用提供独特的机会。我们建议通过检查移植前、移植后和移植后完成雷帕霉素治疗后获得的样品的混合淋巴细胞反应（MLRs）和细胞内细胞因子染色（ICS）来做到这一点。我们将确定雷帕霉素的持续存在是否有必要在体外抑制异体反应，以及MLR中测量的耐受性是否依赖于Tregs的存在。我们将测试添加雷帕霉素或Tregs是否能够抑制在接受雷帕霉素时发生移植物排斥反应或GVHD的患者的MLR。我们将确定临床排斥或GVHD形式的雷帕霉素耐药是否对应于mTOR靶磷酸化水平的雷帕霉素生化耐药，以及一种新的mTOR激酶抑制剂是否可以在体外克服这种生化耐药。最终目的是确定长期mTOR抑制是否会干扰抗原特异性T细胞细胞因子的产生或导致抗原特异性Tregs的产生，以临床相关的巨细胞病毒或甲型流感。我们相信，更好地了解mTOR抑制的免疫后果将导致更安全和更成功的骨髓移植，从而使这种潜在的治愈性治疗扩大到更多的慢性血液病患者。

DESCRIPTION (provided by applicant): Nonmyeloablative bone marrow transplant offers a safe, potentially curative treatment for non-malignant hematological diseases such as sickle cell anemia. Unfortunately, successful nonmyeloablative transplant to treat sickle cell anemia has been limited due to immune-mediated graft rejection. Our research has demonstrated that rapamycin can promote regulatory T cell (Treg) differentiation of naive T cells and anergy of Th1 cells following T cell activation. We used these observations to develop a novel preparative regimen to inhibit rejection and graft versus host disease (GVHD) by promoting T cell tolerance. Our strategy reduces the frequency of alloreactive T cells with alemtuzumab, creates "space" for engraftment with low dose total body irradiation, and allows lymphocyte recovery under extended rapamycin treatment. In the matched sibling setting this approach has had great success, resulting in stable mixed chimerism that corrects their hematological phenotype of sickle cell anemia and reverses pulmonary hypertension. Based on this success, a second clinical trial was developed to expand the potential donor pool to include haploidentical related donors, greatly increasing potential availability of this therapy to patients. The new trial employs the same fundamental principles in the choice of preparative regimen with the addition of dose escalation of post transplant cyclophosphamide to further reduce alloreactive T cells that could contribute to rejection or GVHD. Peripheral blood samples from patients and donors on this trial will provide a unique opportunity to systematically investigate the role of T cell tolerance in promoting stable chimerism. We propose to do this by examination of mixed lymphocyte reactions (MLRs) and intracellular cytokine staining (ICS) from samples obtained pretransplant, posttransplant on rapamycin, and posttransplant after completion of rapamycin therapy. We will determine whether the continued presence of rapamycin is necessary to suppress allogeneic responses in vitro and whether the tolerance measured in the MLR is dependent on the presence of Tregs. We will test whether addition of rapamycin or Tregs is able to suppress the MLR from a patient who develops graft rejection or GVHD while receiving rapamycin. We will determine if clinical resistance to rapamycin in the form of rejection or GVHD corresponds to biochemical resistance to rapamycin at the level of mTOR target phosphorylation and whether a novel mTOR kinase inhibitor can overcome such biochemical resistance in vitro. A final aim is to determine whether prolonged mTOR inhibition interferes with antigen specific T cell cytokine production or leads to generation of antigen specific Tregs to clinically relevant CMV or influenza A. We believe that a better understanding of the immunologic consequences of mTOR inhibition will result in safer and more successful bone marrow transplantation, allowing expansion of this potentially curative therapy to a wider number of patients with chronic hematologic illnesses. PUBLIC HEALTH RELEVANCE (provided by applicant): Sickle cell anemia and other chronic anemias impose a huge burden of pain and suffering for patients and large health care costs related to hospitalizations and chronic transfusion/chelation therapy. In this proposal we seek to define the operative cellular and biochemical processes that promote T cell tolerance in a novel protocol to cure sickle cell disease with non-myeloablative bone marrow transplantation. It is hoped that the results of this study will allow safer application of this curative therapy to a greater number of patients and aid in improving tolerogenic therapy for autoimmunity and solid organ transplantation as well.