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）是异基因造血干细胞/骨髓移植（BMT）的严重T细胞介导的并发症，并且胃肠道损伤是急性GVHD相关的发病率和死亡率的主要贡献者。免疫系统具有通过释放细胞因子来调节GVHD诱导的损伤后的胃肠恢复的能力。然而，在GVHD中同种异体T细胞和受体肠干细胞（ISC）之间发生的直接相互作用知之甚少。我们推测，ISCs将表达死亡受体，参与其免疫介导的消除GVHD。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代表了测试免疫介导的ISC隔室调节和开发减少GVHD中的组织损伤的新方法的极好的实验系统。在这个项目中，我们将使用肠道类器官培养来测量体内GVHD和体外肠道同种异体反应模型。为了阐明免疫介导的损伤对骨髓移植后ISC区室的作用，我们提出了以下具体目标：（1）分析骨髓移植后ISC的活力，细胞周期进程和凋亡，（2）评估产生ISC损伤的T细胞亚型和活化状态，（3）检查调节对ISC的同种异体反应性的细胞通路。这项研究项目将大大有助于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.