Expansion of alloantigen reactive Tregs for transplantation tolerance

描述(申请人提供)：一小部分T淋巴细胞表达FoxP3，被称为调节性T细胞或Tregs。为了治疗许多人类疾病或与疾病相关的并发症，经常需要进行各种器官移植。然而，移植的组织需要在宿主T淋巴细胞的排斥反应中存活下来。宿主来源的供体特异性Tregs提供了一种自然的方法来抑制移植器官的排斥反应，没有副作用，也没有与免疫抑制药物相关的靶点。Tregs被发现的频率很低，动物模型表明，需要大量的Tregs才能达到临床疗效；因此，阐明Tregs扩增的机制将有助于这一特定T淋巴细胞亚群在诱导移植耐受方面的治疗应用。我们发现，持续和聚集的CD3和CD28信号诱导效应T细胞凋亡，并允许在不到2周的时间内扩增Tregs。在此条件下培养12天的未分选的人CD4T细胞(最初为6%的FoxP3+细胞)对Tregs(培养结束时75%的细胞Foxp3+细胞)具有高度的富集性。因此，该方法在Tregs的临床应用中具有很大的前景和潜力。这项研究将详细研究小鼠和人类供体反应性Tregs的扩增以诱导移植耐受，并阐明该系统中选择性Treg扩增的机制。目的1验证Treg特异性转录因子FoxP3在该系统中主动抑制细胞凋亡，允许Treg选择性增殖和扩增的假说。目的2利用MHC-肽四聚体诱导TCR连接，验证固定化MHC-肽四聚体和抗CD28选择性扩增小鼠和人类同种异体抗原特异性Tregs的假说。这些研究的结果将极大地促进Tregs的临床应用，以提高移植耐受性。 公共卫生相关性：调节性T细胞为受者提供了一种自然的方式，可以延长移植器官的寿命，而不会产生副作用。利用一种新的系统，拟议的研究旨在扩大同种异体反应树，以促进长期接受不匹配的受者的移植组织。

DESCRIPTION (provided by applicant): A small subset of T lymphocytes expresses FoxP3 and is called as regulatory T cells or Tregs. Transplantation of various organs is often required to treat many human diseases or disease-related complications. However, transplanted tissues need to survive rejection by host T lymphocytes. Host-derived donor-specific Tregs offer a natural way of suppressing rejection of transplanted organs without side effects or off targets associated with immunosuppressive drugs. Tregs are found at very low frequency and animal models have shown that large numbers of Tregs are required to achieve clinical efficacy; therefore elucidation of the mechanisms underlying the expansion of Tregs will facilitate the therapeutic application of this specific subset of T lymphocytes for induction of transplantation tolerance. We have found that sustained and clustered CD3 and CD28 signaling induces apoptosis of effector T cells and allows expansion of Tregs in less than 2 weeks. Unsorted human CD4 T cells (initially 6% FoxP3+ cells) cultured for 12 days under this condition were highly enriched for Tregs (>75% cells Foxp3+ cells at end of culture). Therefore, this procedure has great promise and potential for clinical application of Tregs. The proposed study will investigate in detail the expansion of donor reactive Tregs from mice and humans for induction of transplantation tolerance and elucidate the mechanism of selective Treg expansion in this system. Aim 1 will test the hypothesis that Treg specific transcription factor FoxP3 actively suppresses apoptosis in this system, allowing selective proliferation and expansion of Tregs. Aim 2 will employ MHC-peptide tetramers for induction of TCR ligation to test the hypothesis that sustained and clustered signaling by immobilized MHC-peptide tetramers and anti-CD28 selectively expand alloantigen specific functional Tregs from mice and humans. The outcome of these studies will greatly facilitate clinical application of Tregs to improve transplantation tolerance. PUBLIC HEALTH RELEVANCE: Regulatory T cells offer a natural way of inducing longevity of transplanted organs to recipients without side effects. Using a novel system, proposed study aims to expand alloreactive Tregs to facilitate the long term acceptance of transplanted tissue to mismatch recipients.