Depletion, Repopulation and Tolerance in Non-Sensitied Recipients

摘要-项目1（Kirk，项目负责人） 肾移植的巨大益处被与慢性肾移植相关的许多并发症所抵消。 免疫抑制治疗超过95%的患者使用基于钙调磷酸酶抑制剂（CNI）的方案，但 这些不加选择地损害免疫过程，包括促进移植物接受的免疫过程， 严重的副作用。共刺激阻断（CoB），特别是CD 28-CD 80/86通路抑制，已经被广泛应用于临床。 与CNI相比，CNI可促进移植物的长期存活，且副作用更少，最近的临床试验表明， 表明淋巴细胞耗竭促进了基于CoB的方案，不仅防止了排斥反应， 适应性过程，随着时间的推移减少对免疫抑制的需求，并促进同种异体特异性 宽容该项目旨在定义淋巴细胞耗竭的要素，这些要素促进基于CoB的 宽容我们已经表明，淋巴细胞耗竭，以及随后的稳态再增殖， 有机会塑造同种异体反应性免疫库，以促进耐受，但也带来了破坏免疫系统的风险。 调节，并引发病毒感染、自身免疫和同种异体反应性克隆的激活。我们的实验计划 试图理解消耗感应的这两个方面。我们假设， 治疗性淋巴细胞耗竭不是由直接消除CoB抗性细胞驱动的，而是由 产生淋巴细胞更新和胸腺输出的刺激，促进抗原特异性活化诱导的细胞 死亡（AICD）。从这个角度来看，消耗的方法从细胞消除转变为促进和 管理再增殖，后者由相对（而不是绝对），成熟定义的能力控制， 残留淋巴细胞群对抗原暴露、次级淋巴器官功能和 免疫抑制我们认为，这些因素是易处理的，可以治疗操纵。到 为了探索这一点，我们提出了3个具体目标：具体目标1：我们将定义耗竭诱导的影响 恒河猴中的方案（广泛多克隆或靶向单克隆抗体介导的消除） 在接受肾移植的患者中，比较CNIs和mTOR抑制剂对体内平衡的影响， 再增殖，并将这些与贝拉西普诱导的耐受性的功效相关。目标2：我们将定义 胸腺或脾脏切除或放射对同种异体细胞稳态再增殖的影响。 具体目标3：我们将确定供体和病毒（CMV）抗原暴露对再增殖的影响， 耐受，以骨髓或间充质干细胞的形式提供延长的供体抗原，和 在未感染CMV的动物和胸腺照射的动物中研究这些方案。所有的研究都将是沉重的 机械地支持评估表型，特异性和功能的重建库。我们 将与项目2合作，以确定这些演习对同种抗体形成的影响，并将 与项目2的结果，建立一个范式，以指导开发一个优化的 与CoB配对的消耗方案。

ABSTRACT – Project 1 (Kirk, Project Lead) Kidney transplantation's considerable benefit is offset by the many complications associated with chronic immunosuppressive therapy. Calcineurin inhibitor (CNI)-based regimens are used by over 95% of patients, but these indiscriminately impair immune processes, including those that facilitate graft acceptance, and produce significant side effects. Costimulation blockade (CoB), particularly CD28-CD80/86 pathway inhibition, has been shown to promote long-term allograft survival with fewer side effects than CNIs, and recent clinical trials have suggested that lymphocyte depletion fosters CoB-based regimens, not only preventing rejection, but fostering adaptive processes that reduce the needs for immunosuppression with time, and promoting allospecific tolerance. This project seeks to define the elements of lymphocyte depletion that foster CoB-based tolerance. We have shown that lymphocyte depletion, and subsequent homeostatic repopulation, present opportunities to shape the alloreactive immune repertoire to favor tolerance, but also poses risks to disrupt regulation, and ignite viral infection, autoimmunity and activation of alloreactive clones. Our experimental plan seeks to understand these two sides of depletional induction. We hypothesize that the effectiveness of therapeutic lymphocyte depletion is NOT driven by direct elimination of CoB-resistant cells, but rather by creating a stimulus for lymphocyte turnover and thymic output, fostering antigen-specific activation induced cell death (AICD). Viewed this way, the approach to depletion changes from cell elimination, to promoting and managing repopulation, the latter controlled by relative (not absolute), maturation-defined susceptibilities of the residual lymphocyte population to the effects of antigen exposure, secondary lymphoid organ function, and immunosuppression. We posit that these factors are tractable, and can be therapeutically manipulated. To explore this, we propose 3 specific aims: Specific Aim 1: We will define the effects of depletional induction regimens (broad polyclonal or targeted monoclonal antibody mediated depletion) in rhesus monkeys undergoing kidney transplantation, comparing the effects of CNIs and mTOR inhibitors on homeostatic repopulation, and relate these to the efficacy of belatacept-induced tolerance. Specific Aim 2: We will define the impact of thymic or splenic resection or irradiation on homeostatic repopulation of allospecific cells. Specific Aim 3: We will define the impact of donor and viral (CMV) antigen exposure on repopulation and tolerance, providing prolonged donor antigen in the form of bone marrow or mesenchymal stem cells, and studying these regimens in CMV naïve animals, animals with thymic irradiation. All studies will be heavily mechanistically supported to assess the phenotype, specificity and function of the repopulating repertoire. We will partner with Project 2 to define the impact of these maneuvers on alloantibody formation, and matrix the results in the Project with those of Project 2 to establish a paradigm to guide the development of an optimized depletional regimen to pair with CoB.