Regulatory T cells in Highly Sensitised Renal Patients to Improve Outcomes after HLA-Antibody Incompatible Transplantation.

肾移植是治疗肾衰竭患者的金标准。它提供了一个更好的质量和更长的寿命比替代品，这是透析。然而，三分之一等待肾移植的患者对称为人类白细胞抗原（HLA）的组织蛋白高度敏感，无论是通过先前的输血，怀孕或先前的肾移植，这导致循环中出现针对HLA的抗体（Ab）。Ab显著增加了等待合适肾脏的时间。这些患者有两种选择：要么等待长时间透析以获得匹配的器官，要么在移植前进行“脱敏”以去除Ab;主管AD和他的同事们的工作表明，这种方法提供了与等待透析相同的患者生存率。虽然“脱敏”提供了一种移植这些患者的方法，但他们通常在几天内对肾脏产生了积极的免疫反应，由于存在免疫“记忆”，存在于免疫系统的细胞内;因此，这些患者具有较高的早期排斥、“郁积”或慢性排斥和移植失败率，并且由于他们接受较高水平的免疫抑制以预防和治疗这些并发症，感染并发症率较高。因此，这些患者的移植结果不如在非致敏受者中看到的结果。AD主管先前的工作强调，一些但不是所有对HLA致敏的患者能够抑制记忆免疫应答，这是由于他们保留了称为调节性T细胞（Tcells）的特化细胞，其在自然界中作为抑制炎症反应和预防自身免疫性疾病的防御机制而存在。因为我们知道，从他们的HLA抗体谱，特定的HLA，患者是敏感的，因为特定的HLA蛋白质现在是商业上可获得的高度纯化的重组蛋白，它是可能的测试记忆反应的个人使用的测定称为ELISPOT测定。我的项目的第一部分将是研究高度致敏患者中THBG的数量和特征，并测试它们是否保留抑制对特定HLA蛋白质反应的能力。出于实用目的，我将把我的分析限制在最多20名患者，并研究他们具有低水平抗体的HLA。GL主管是Treg细胞群分离和扩增方面的专家，迄今已在2项英国试验中监督了临床级细胞对移植患者的给药。我的项目的第二部分将是从患者中分离和扩增特定的TCL 4亚群，以测试这些亚群是否可以在体外通过滴定到ELISPOT测定中来抑制对HLA的反应，作为如果我们将TCL 4给予这些患者可能发生的情况的替代。我还将测试是否操纵TdR，以增强他们与记忆细胞相互作用的能力，增强他们的抑制能力。最后，两名主管目前正在计划一项试验，在2019年对移植等待名单上的患者进行临床级Treg治疗，目前正在准备资金申请。该试验的目的是评估是否有可能稳健地检测TdR对HLA记忆反应的影响。因此，我的项目的第三部分将是研究ELISPOT对试验患者中特定HLA蛋白的反应，特别是询问第1部分和第2部分中的体外观察结果是否可以通过体内施用TdR来重现。我在这一部分的工作将直接关系到是否进行第二次治疗试验，将TdR与常规疗法在即将接受移植的患者中进行比较。

Kidney transplantation is the gold-standard treatment for patients with kidney failure. It offers a better quality and longer life than the alternative, which is dialysis. However, one-third of patients awaiting a kidney transplant are highly sensitized to tissue proteins called human leukocyte antigens (HLA), either through a previous blood transfusion, pregnancy, or a prior kidney transplant, which results in the appearance of antibodies (Ab) against HLA in the circulation. The Ab significantly increase the time spent awaiting a suitable kidney. These patients have two options: either wait a long time on dialysis for a matched organ or undergo 'desensitization' to remove Ab before transplantation; work from the supervisor AD and his colleagues have shown that this approach offers equivalent patient survival compared to waiting on dialysis.Although 'desensitization' offers a way to transplant these patients, they mount aggressive immune responses to the kidney, usually within a few days, consequent on the presence of immunological 'memory', residing within cells of the immune system; therefore, these patients have higher rates of early rejection, 'smouldering' or chronic rejection and graft failure and, because of the higher levels of immunosuppression they receive to prevent and treat these complications, a higher rate of infectious complications. Therefore, transplant outcomes in these patients are inferior to those seen in non-sensitized recipients.Previous work from supervisor AD has highlighted that some, but not all patients who are sensitized to HLA are able to suppress memory immune responses, by virtue of the fact they retain specialized cells called regulatory T cells (Tregs), which exist in nature as a defence mechanism to suppress inflammatory responses and prevent autoimmune diseases. Because we know, from their HLA Ab profiles, the specific HLA to which patients are sensitized, and because specific HLA proteins are now commercially available as highly purified recombinant proteins, it is possible to test memory responses in individuals using assays called ELISPOT assays. The first part of my project will be to study the numbers and characteristics of Tregs in highly sensitized patients and test whether they retain the ability to suppress responses to specific HLA proteins. For practical purposes, I will limit my analysis to a maximum of 20 patients and study the HLA to which they have low-level Ab. The supervisor GL is an expert on the isolation and expansion of Treg populations and has so far supervised the administration of clinical grade cells to transplant patients in 2 UK trials. The second part of my project will be to isolate and expand particular subpopulations of Tregs from patients to test whether these can be used in vitro to suppress the responses to HLA by titrating into the ELISPOT assay, as a surrogate for what might happen if we were to administer Tregs to these patients. I will also test whether manipulating Tregs, to enhance their ability to interact with memory cells, enhances their suppressive ability. This part of the project will inform the future direction of therapeutic Treg trials in these patients.Finally, both supervisors are currently planning a trial to administer clinical grade Tregs to patients on the transplant waiting list in 2019 - at present, a request for funding is being prepared. The purpose of the trial will be to assess whether it is possible to robustly detect the impact of Tregs on memory responses to HLA. Therefore the third part of my project will be to study ELISPOT responses to specific HLA proteins in the trial patients, specifically to ask whether the in vitro observations in part 1&2 can be reproduced by administering Tregs in vivo. My work in this part will have a direct bearing on whether a second therapeutic trial, comparing Tregs to conventional therapy in patients about to be transplanted, is performed.