Deciphering the mechanisms of intestinal stem cell elimination by allogeneic T cells in order to develop novel GVHD treatment approaches

移植物抗宿主病（GVHD）是同种异体造血干细胞/骨髓移植（BMT）的一种严重的T细胞介导的并发症，胃肠道损伤是急性GVHD相关发病率和死亡率的主要因素。免疫系统具有通过释放细胞因子调节gvhd诱导损伤后胃肠道恢复的能力。然而，同种异体T细胞与受体肠干细胞（ISC）间室在GVHD中发生的直接相互作用尚不清楚。我们假设，在GVHD中，ISCs会表达参与免疫介导消除的死亡受体。鉴于临床急性GVHD与其实验模型之间的高度一致性，胃肠道GVHD是一个很好的实验系统，可以测试免疫介导的ISC室调节，并开发新的方法来减少GVHD的组织损伤。在本项目中，我们将使用肠道类器官培养来测量体内GVHD并在体外模拟肠道同种异体反应性。为了阐明BMT后免疫介导的ISC室损伤的作用，我们提出以下具体目标：(1)分析BMT后ISC的活力、细胞周期进程和凋亡；(2)评估造成ISC损伤的T细胞的亚型和激活状态；(3)研究调节ISC同种异体反应的细胞途径。该研究项目将极大地促进我们对粘膜免疫学的理解，并可能导致新的GVHD治疗方法的发展。

Graft-versus-host disease (GVHD) is a severe T cell-mediated complication of allogeneic hematopoietic stem cell/bone marrow transplantation (BMT), and damage to the gastrointestinal tract is the predominant contributor to acute GVHD-related morbidity and mortality. The immune system has the capability to regulate gastrointestinal recovery after GVHD-induced injury by release of cytokines. However, the direct interactions occurring between allogeneic T cells and recipient intestinal stem cell (ISC) compartment in GVHD are poorly understood. We hypothesize that ISCs will express death receptors that are involved in their immune-mediated elimination in GVHD. Given the high concordance between clinical acute GVHD and its experimental models, gastrointestinal GVHD represents an excellent experimental system to test immune-mediated regulation of the ISC compartment and develop novel approaches to reduce tissue damage in GVHD. In this project, we will use intestinal organoid cultures to measure in vivo GVHD and model intestinal alloreactivity in vitro. In order to elucidate the role of immune-mediated damage to the ISC compartment after BMT, we propose to test the following specific aims: (1) analyze viability, cell cycle progression, and apoptosis of ISCs post-BMT, (2) evaluate subtype and activation status of T cells exerting ISC damage, (3) examine cellular pathways regulating alloreactivity towards ISCs. This research project will contribute substantially to our understanding of mucosal immunology and may lead to the development of novel GVHD treatment approaches.