Depletion, Repopulation and Tolerance in Sensitized Recipients

虽然在美国大多数肾移植手术中使用多克隆抗体或阿仑妥珠单抗进行围手术期免疫细胞清除，但我们的实验室已经在人类和非人灵长类动物（NHP）中显示，清除后的稳态再生与B细胞激活、BAFF水平升高和新生供体特异性同种抗体（DSA）有关。我们还表明，Belatacept能够抑制NHP耗竭后的DSA。最近，我们在一个现显化的NHP模型中表明，阻断CD28和CD154结合蛋白酶体抑制可显著降低移植前的同种异体抗体水平，破坏生发中心并降低浆细胞数量。然而，仅通过蛋白酶体抑制浆细胞的消耗也与生发中心和Tfh细胞激活有关。因此，免疫细胞的耗竭导致耐受性方面的有益和有害后果。该项目旨在确定致敏宿主中促进耐受性的免疫细胞耗竭的要素。我们认为，淋巴细胞和浆细胞耗损以及随后的稳态再生，既提供了塑造同种异体免疫库以促进耐受性的机会，也存在破坏调节、引发病毒感染和诱导同种异体克隆激活的风险。我们假设，致敏宿主的免疫细胞耗竭的后果通过免疫系统产生可预测的代偿反应，需要治疗控制以促进耐受性。为了探索这一假设，我们提出了3个具体目标：1)在肾移植前使用蛋白酶体抑制和辅助治疗，开发更安全、更有效的方法来降低阻止同种异体移植的同种异体抗体、浆细胞和记忆B细胞的数量和数量；2)利用耗损、供者特异性输血和雷帕霉素重塑免疫库，以促进致敏受体的调节、AICD和促耐受稳态重建；3)评价Belatacept联合和不联合雷帕霉素作为移植后免疫抑制方案的组成部分，促进同种异体肾移植在上述SA1和sa2中脱敏治疗后的长期生存的安全性和有效性。

While perioperative immune cell depletion with either polyclonal antibody or alemtuzumab is used in the majority of renal transplants in the U.S., our lab has shown in both humans and non-human primates (NHP) that homeostatic repopulation following depletion is associated with B cell activation, elevated BAFF levels, and de novo donor-specific alloantibody (DSA). We have also shown that Belatacept is capable of suppressing such DSA in NHP following depletion. Recently, we have shown in a presensitized NHP model that blockade of CD28 and CD154 in combination with proteasome inhibition substantially lowers alloantibody levels pre-transplant, disrupting germinal centers and lowering plasma cell numbers. However, depletion of plasma cells by proteasome inhibition alone is also associated with germinal center and Tfh cell activation. Thus, depletion of immune cells leads to both beneficial and deleterious consequences with respect to tolerance. This project seeks to define the elements of immune cell depletion in sensitized hosts that foster tolerance. We believe that lymphocyte and plasma cell depletion and subsequent homeostatic repopulation present both an opportunity to shape the alloreactive immune repertoire to favor tolerance, and a risk to disrupt regulation, ignite viral infection and induce activation of alloreactive clones. We hypothesize that the consequences of immune cell depletion in sensitized hosts create compensatory responses by the immune system that are predictable and need to be therapeutically controlled to promote tolerance. To explore this hypothesis, we propose 3 specific aims: 1) To develop safer and more effective means to lower the amount and number of allospecific antibodies, plasma cells, and memory B cells that prevent allotransplantation using proteasome inhibition together with complementary adjuvant therapies prior to renal transplantation; 2) To reshape the immune repertoire using depletion, donor-specific transfusion, and rapamycin to promote regulation, AICD, and pro-tolerant homeostatic repopulation in the sensitized recipient; and 3) To evaluate the safety and efficacy of Belatacept with and without Rapamycin as components of post-transplant immunosuppressive regimens promoting long-term survival of renal allografts following desensitization therapy as described in SA1 and 2 above.