Liver allograft tolerance induction by Bcl-2 inhibition and delayed donor bone marrow infusion

项目摘要/摘要 尽管肝脏长期以来一直被认为是耐受性器官，但大多数肝移植接受者需要终生 免疫抑制，这可能会产生负面后果，如病毒性肝炎或 肝细胞癌。所有的移植受者，无论是什么器官，都有更高的发病风险。 慢性肾脏疾病、感染、恶性肿瘤或心血管疾病。因此，耐受性诱导， 在同种异体移植和患者存活方面将是一个重要的长期好处。 我们已经成功地通过使用混合嵌合体方法和 人类和非人类灵长类动物(NHP)的非清髓方案。然而，它的临床应用 这种方法在肝移植接受者中的应用不如在肾移植接受者中实用或安全，因为 肝功能衰竭患者在移植时往往病情较重，无法抵抗... 调理养生法。然而，如果骨髓移植被推迟，如果我们减少了 骨髓抑制调节方案，这些方法可以安全地应用。Cippa等人。最近报道的 一种无骨髓抑制的B细胞造血干细胞移植新方法 淋巴瘤-2(Bcl2)抑制物。这一新的方法已经成功地转化为NHP肾脏移植 模特。 使用FDA批准的高度选择性的Bcl-2抑制剂ABT-199(万乃馨)，总剂量减少(1.5G) 体内照射(TBI)，我们已经能够显著改善混合嵌合体和同种异体肾移植 NHP中的耐受性。在这些初步结果的鼓舞下，我们假设嵌合体和肝脏混合 在没有任何骨髓抑制治疗的情况下，可以更有效地诱导同种异体移植耐受。初级阶段 本方案的目的是评价选择性抑制Bcl-2诱导混合嵌合体的疗效。 临床相关NHP模型中的同种异体肝移植耐受。将使用人类白细胞抗原不匹配的食蟹猴 作为同种异体原位肝移植的供体和受体。所有收件人最初都将收到 符合移植围手术期的三联免疫抑制方案(环磷酰胺、霉酚酸酯、类固醇)。几个 在原位肝移植(OLTx)后2-3个月，受者将接受非清髓性调节 (胸腺照射，加或不加ABT-199)和DBMT，随后是移植后的短疗程 B latacept(20 mg/kg，d0，2，5，12天)和1个月的CyA疗程，观察Bcl2抑制剂是否能 诱导混合嵌合体和同种异体肝移植耐受。然后我们将研究抑制Bcl-2对血管内皮细胞生长的影响 探讨同种异体反应性T淋巴细胞和调节性T细胞的作用机制。

PROJECT SUMMARY / ABSTRACT Although the liver has long been considered a tolerogenic organ, most liver transplant recipients require lifelong immunosuppression, which can have negative consequences, such as recurrence of viral hepatitis or hepatocellular carcinoma. All transplant recipients, regardless of organ, have an increased risk of developing chronic kidney disease, infection, malignancies, or cardiovascular disease. Tolerance induction, therefore, would be a significant long-term benefit in terms of allograft and patient survival. We have successfully achieved renal allograft tolerance using a mixed chimerism approach in concert with a non-myeloablative regimen in both humans and non-human primates (NHPs). However, the clinical application of this approach in liver transplant recipients is not as practical or safe as in kidney transplant recipients because liver failure patients tend to be sicker at the time of transplantation and unable to withstand the toxicity of the conditioning regimen. However, if the bone marrow transplant is delayed and if we reduce the toxicity of the myelosuppressive conditioning regimen, these approaches can be safely applied. Cippa et al. recently reported a novel approach to hematopoietic stem cell (HSC) engraftment without myelosuppression using a B cell lymphoma-2 (Bcl-2) inhibitor. This novel approach has been successfully translated to an NHP kidney transplant model. Using an FDA-approved, highly selective Bcl-2 inhibitor, ABT-199 (venetoclax), with reduced dose (1.5 G) total body irradiation (TBI), we have been able to achieve significantly improved mixed chimerism and renal allograft tolerance in NHPs. Encouraged by these preliminary results, we hypothesize that mixed chimerism and liver allograft tolerance can be induced even more effectively without any myelosuppressive treatments. The primary objective of this proposal is to evaluate the efficacy of selective Bcl-2 inhibition to induce mixed chimerism for liver allograft tolerance in a clinically relevant NHP model. HLA mismatched cynomologus monkeys will be used as both donors and recipients for allogeneic orthotopic liver transplantation. All recipients will initially receive triple-drug immunosuppressive regimen (CyA, MMF, steroid) consistent with the peri-transplant period. Several months (2-3) after orthotopic liver transplant (OLTx), the recipients will undergo non-myeloablative conditioning (thymic irradiation, with or without ABT-199) and DBMT, followed by a short post-transplant course of Belatacept (20mg/kg on days 0, 2, 5 and 12) and one month course of CyA to see whether Bcl-2 inhibitor can induce mixed chimerism and liver allograft tolerance. We will then study the effect of Bcl-2 inhibition on alloreactive T lymphocytes and regulatory T cells to investigate the mechanism.