Targeting innate immunity for induction of robust renal allograft tolerance

摘要 建立一种可靠的方法来实现同种异体移植耐受仍然是器官移植的最终目标。 我们之前曾报道过人类移植肾长期无免疫抑制存活。 仅通过供者骨髓移植诱导一过性造血嵌合体。要扩展 应用我们的方法，现在当务之急是1)提高造血系统的一致性和稳健性 嵌合体和同种异体移植耐受；2)通过寻找新的诱导剂来完善条件调节方案 没有遗传毒性不良影响的混合嵌合体；以及3)扩大了对其机制的理解 通过诱导短暂的混合嵌合体，实现了无I.S.的同种异体肾移植接受。 有充分的证据表明，移植围手术期的促炎反应会对长期的- 同种异体移植的远期结局和耐受诱导。整合素CD11b/CD18(CD11b)高表达于 在天然免疫细胞表面，并调节天然免疫细胞中几个关键的促炎功能。 我们先前的研究表明，CD11b的一级纯拮抗剂mAb107可以阻断CD11b， 显著限制自体肾或同种异体肾移植长时间热缺血后的再灌注损伤 非人灵长类动物。这些观察结果导致了我们对这一应用的初步研究，显示出优越的 单抗107受者肾移植的长期结果以及改善的造血细胞嵌合体。 因此，在目标1中，我们将测试在我们的混合嵌合体中用mAb107阻断CD11b的假设 方案将诱导更强大的同种异体移植耐受性。 为了减少我们的骨髓移植预适应方案的并发症，我们最近表明 万乃克选择性抑制Bcl2基因可显著促进造血嵌合体和同种异体移植耐受 伴有最小的骨髓抑制并发症。然而，完全消除遗传毒性治疗 预适应方案不能抑制Bcl2和最小无毒剂量的全身照射 (TBI)仍然是必需的。ImmTOR是一种人工合成的可生物降解的纳米颗粒，包裹着雷帕霉素。它可以是 被树突状细胞和其他髓系细胞快速内吞，并诱导抗原特异性无应答 在NHP和人类中。因此我们推测，ImmTOR强大的免疫调节作用可能不止于 有效地保护同种异体造血干细胞免受同种异体免疫反应，允许在没有任何 基因毒性治疗。我们对ImmTOR的初步研究对多血统混合嵌合体的研究令人鼓舞 未经放疗和化疗即可诱导。 最后，我们将阐明肾移植成功存活的机制。 MAb107和ImmTOR在体内外广泛诱导的一过性造血嵌合 用新的免疫学方法进行实验。我们的假设是，主要的耐受机制将 被定义为监管，但也涉及删除机制。

SUMMARY Establishing a reliable method to achieve allograft tolerance remains an ultimate goal in organ transplantation. We previously reported long-term immunosuppression (I.S.)-free renal allograft survival in humans after induction of only transient hematopoietic chimerism through donor bone marrow transplantation. To expand the application of our approach, it is now imperative to 1) improve the consistency and robustness of hematopoietic chimerism and allograft tolerance; 2) refine the conditioning regimen by identifying novel agents that can induce mixed chimerism without genotoxic adverse effects; and 3) expand the understanding of mechanisms whereby I.S.-free renal allograft acceptance via induction of transient mixed chimerism is achieved. There is ample evidence that proinflammatory responses during the peri-transplant period adversely affects long- term outcome of the allograft and tolerance induction. Integrin CD11b/CD18 (CD11b) is highly expressed on the surface of innate immune cells and modulates several key proinflammatory functions in innate immune cells. Our previous studies showed that blocking CD11b with mAb107, a first-in-class pure antagonist of CD11b, markedly limits reperfusion injury after prolonged warm ischemia of native kidney or kidney allografts in nonhuman primates. These observations led to our preliminary studies for this application that revealed superior long-term outcome of renal allografts as well as improved hematopoietic chimerism in recipients of mAb107. Therefore, in Aim 1, we will test the hypothesis that blocking CD11b with mAb107 in our mixed chimerism protocol will induce a more robust allograft tolerance. To reduce comorbidity of our conditioning regimen for bone marrow transplantation, we recently showed that selective Bcl-2 inhibition with Venetoclax significantly promotes hematopoietic chimerism and allograft tolerance with minimal myelosuppressive complications. However, complete elimination of genotoxic treatments from the conditioning regimen was not achieved with Bcl-2 inhibition and a minimal non-toxic dose of total body irradiation (TBI) was still required. ImmTOR is synthetic biodegradable nanoparticles encapsulating rapamycin. It can be rapidly endocytosed by dendritic cells and other myeloid cells and induces antigen-specific non-responsiveness in NHPs and humans. We therefore hypothesize that potent immunomodulatory effects of ImmTOR may more effectively protect allogeneic HSCs from alloimmune responses, allowing engraftment of HSCs without any genotoxic treatments. Our preliminary studies with ImmTOR are encouraging with multilineage mixed chimerism being induced without irradiation and chemotherapy. Finally, we will elucidate the mechanistic pathways involved in successful I.S.-free renal allograft survival by transient hematopoietic chimerism induced by mAb107 and ImmTOR, utilizing extensive in vitro and in vivo experiments with novel immunological approaches. Our hypothesis is that the major tolerance mechanism will be defined as regulatory but deletional mechanisms are also involved.