Alemtuzumab and Regulatory T Cells for Heart Transplant Tolerance in Monkeys

我们提出的研究将探讨调节性T细胞（Treg）促进食蟹猴对异位异体心脏移植耐受的潜力。基于小动物研究的有说服力的证据表明，在给予Treg之前消耗T效应细胞有利于Treg诱导的免疫调节的结果。我们在印度尼西亚食猴身上开发了一种T细胞消耗方案，使用人源化抗cd52单抗（阿仑妥珠单抗）联合霉酚酸酯（MMF）。CD3[+]T细胞可维持极低的数量，周期约为4周，CD4[+] T细胞可维持数月。我们还分离并成功扩增了猴Treg，并证明了它们的免疫调节特性。我们假设移植后将自体Treg过继转移到淋巴细胞枯竭的宿主，并结合一个疗程的雷帕霉素单药治疗，将提高同种异体心脏移植的存活率并促进耐受性诱导。我们提出的研究有以下目的：目的一：确定阿仑单抗对食蟹猴同种异体心脏移植结果和宿主免疫反应性的影响；Aim II将评估多克隆Treg（扩增的天然Treg或诱导Treg）对阿仑单抗治疗猴子心脏移植结果和潜在机制的影响，并将结果与Aim I的结果进行比较；Aim III将评估同种异体抗原特异性Treg促进阿仑单抗治疗猴子心脏移植结果的能力和潜在机制，并将与Aim I和II的结果进行比较。在每个Aim中，Treg将在初始T细胞耗尽和心脏移植（第0天）后的第21天施用；免疫抑制治疗将逐渐减少，并在3个月时停止。移植后随访6个月。结果将通过(i)移植物存活时间，（ii）移植物血管病变（慢性排斥）的发生率，（iii）抗供体T细胞反应的发展，（iv）抗供体抗体（Abs）的发展，(v)抗静脉蛋白和抗肌球蛋白抗体的发展，以及T细胞对这些自身抗原的反应，以及（vi）记忆T细胞反应的评估来监测。此外，在Aims II和III中，我们将确定Treg治疗对宿主免疫反应性和移植结果影响的机制基础。这些研究将为过继性移植自体Treg诱导非人类灵长类动物心脏异体移植耐受或适当耐受状态的能力提供明确的信息，并可能为临床试验提供足够的数据。

Our proposed studies will investigate the potential of regulatory T cells (Treg) for the promotion of tolerance to heterotopic heart allografts in cynomolgus monkeys. There is persuasive evidence, based on small animal studies, that depletion of T effector cells prior to the administration of Treg is advantageous to the outcome of Treg-induced immunomodulation. We have developed a T cell-depleting regimen in Indonesian cynomolgus monkeys, using humanized anti-CD52 mAb (alemtuzumab) in combination with mycophenolate mofetil (MMF). CD3[+]T cells can be maintained at very low numbers for periods >4 weeks, and CD4[+] T cells for several months. We have also isolated and successfully expanded monkey Treg and demonstrated their immunomodulatory properties. We hypothesize that posttransplant adoptive transfer of autologous Treg to lymphocyte-depleted hosts, in combination with a course of rapamycin monotherapy, will enhance heart allograft survival and promote tolerance induction. Our proposed investigations have the following Aims: Aim I will determine the Influence of alemtuzumab on heart allograft outcome and host immune reactivity in cynomolgus monkeys; Aim II will assess the impact of polyclonal Treg (either expanded naturally-occurring Treg or induced Treg) on heart allograft outcome and underlying mechanisms in alemtuzumab-treated monkeys and will compare the results with those obtained in Aim I; Aim III will assess the ability of alloantigen-specific Treg to promote heart allograft outcome and underlying mechanisms in alemtuzumab-treated monkeys treated as in Aim I and will compare the results with those in Aims I and II. In each Aim, the Treg will be administered on day 21, after the initial T cell depletion and heart transplantation (day 0); immunosuppressive therapy will be tapered and discontinued at 3 months. Follow-up will be for 6 months post transplant. Outcomes will be monitored by (i) length of graft survival, (ii) incidence of graft vasculopathy (chronic rejection), (iii) development of anti-donor T cell responses, (iv) development of anti-donor antibodies (Abs), (v) development of anti-vimentin and anti-myosin Abs, and T cell responses to these autoantigens, and (vi) assessment of memory T cell responses. In addition, in Aims II and III, we will ascertain the mechanistic basis of the influence of the Treg therapy on host immune reactivity and transplant outcome. These studies will provide definitive information on the ability of adoptively-transferred autologous Treg to induce a state of tolerance or prope tolerance to non-human primate heart allografts, and may provide sufficient data to justify a clinical trial.