Suppression of Allograft Rejection by A Novel Protein ESAT-6

描述(申请人提供)：移植的组织或器官总是被接受者拒绝，除非他们在余生中服用免疫抑制药物。然而，传统的免疫抑制药物会产生严重的副作用，包括病毒感染和恶性转化。在没有持续的全球免疫抑制的情况下，实现同种异体移植物的长期存活或耐受是移植的一个非常理想的目标。ESAT-6是一种6 kDa的蛋白质，最初在结核分枝杆菌短期培养滤液中被鉴定为T细胞抗原。大量证据表明，它是促进结核分枝杆菌生长和致病的毒力因子。特别是，ESAT-6已经被证明可以抑制T细胞的增殖。我们的初步研究首次证明ESAT-6促进同种异体胰岛移植物的长期存活，并抑制移植物浸润性T细胞的增殖。因此，ESAT-6可以作为一种新的药物，在缺乏全球免疫抑制剂持续治疗的情况下，诱导移植物的长期存活或耐受。基于这些发现，我们建议进一步研究ESAT-6抑制同种异体移植排斥反应的机制，有两个特定的目的：(1)研究ESAT-6抑制体内和体外同种异体免疫反应的机制。我们将研究ESAT-6在同种异体免疫反应中对T辅助细胞分化为Th1/Th17/Th2细胞以及T细胞向调节性T细胞(Treg)和记忆T细胞(TMEM)发育的影响，因为它们的平衡向Th2或Treg调节倾斜对于同种异体移植物的长期存活至关重要；以及(2)研究在没有或存在短暂和轻度免疫抑制的情况下，ESAT-6是否也促进糖尿病NOD小鼠胰岛移植物的长期存活。这项建议的目标是探索新的策略，在没有或存在短暂和轻度免疫抑制的情况下，使用一种最初由结核分枝杆菌产生的新蛋白来促进他们的生长，以诱导同种异体移植物的长期存活或耐受。这项研究将探讨两组基本的免疫平衡：Th1/Th17/Th2和Treg/TMEM，这两种平衡对决定同种异体移植的命运都是至关重要的。因此，本项目对胰岛移植治疗1型糖尿病以及实体器官移植治疗其他终末期器官疾病具有重要的临床意义。 公共卫生相关性：在没有持续的全球免疫抑制的情况下诱导同种异体移植物的长期存活或耐受是移植的一个非常理想的目标。在这项提议中，我们将利用一种最初由结核分枝杆菌产生的新型药物ESAT-6来促进它们的生长，以促进诱导同种异体胰岛移植物的长期存活或耐受，从而导致通过胰岛移植治愈1型糖尿病患者或通过实体器官移植治愈其他终末期器官疾病的患者。

DESCRIPTION (provided by applicant): Transplanted tissues or organs are always rejected by recipients unless they take immunosuppressive drugs for the rest of their lives. However, traditional immunosuppressive drugs cause serious side-effects including viral infection and malignancy. Achieving long-term allograft survival or tolerance in the absence of continuous global immunosuppression is a highly desirable goal in transplantation. ESAT-6 is a protein of 6 kDa that was originally identified as a T cell Ag in the short-term culture filtrate of M. tuberculosis. Substantial evidence has shown that it is a virulence factor that promotes the growth and pathogenesis of M. tuberculosis. In particular, ESAT-6 has been shown to suppress T cell proliferation. Our preliminary studies for the first time have demonstrated that ESAT-6 promotes the induction of long-term islet allograft survival and suppresses graft-infiltrating T cell proliferation. Therefore, ESAT-6 could be utilized as a novel agent to induce long- term allograft survival or tolerance in the absence of continuous treatment with a globally immunosuppressive agent. Based on these findings, we propose to further study the mechanisms underlying the suppression of allograft rejection by ESAT-6 with two specific aims: (1) To investigate the mechanisms by which ESAT-6 suppresses alloimmune responses in vivo and in vitro. We will investigate the impact of ESAT-6 on T helper cell differentiation into Th1/Th17/Th2 cells and on T cell development into regulatory T (Treg) and memory T (Tmem) cells in the context of alloimmune responses, as tipping their balance toward either Th2 or Treg regulation is critical for long-term allograft survival; and (2) To study whether ESAT-6 also promotes long-term islet allograft survival in diabetic NOD mice in the absence or presence of brief and mild immunosuppression. The goal of this proposal is to explore new strategies to induce long-term allograft survival or tolerance in the absence or presence of brief and mild immunosuppression using a novel protein that is originally produced by Mycobacteria tuberculosis to enhance their growth. This study will look into two basic sets of immunologic balance: Th1/Th17/Th2 and Treg/Tmem, both of which are critical for determining an allograft fate. Therefore this project has important clinical implications for the cure of type 1 diabetes by islet transplantation and perhaps other end-stage organ diseases via solid organ transplantation. PUBLIC HEALTH RELEVANCE: Induction of long-term allograft survival or tolerance without continuous global immunosuppression is a highly desired goal in transplantation. In this proposal, we will utilize a novel agent, ESAT-6 that was originally produced by Mycobacteria tuberculosis to gain their growth, to promote the induction of long-term islet allograft survival or tolerance, leading to a potential cure for patients with type 1diabetes via islet transplantation or other end-stage organ diseases via solid organ transplantation.