The Role of Donor T Cell-Derived GM-CSF in the Pathogenesis of Gastrointestinal Acute GVHD

项目摘要 移植物抗宿主病（GVHD）是异基因造血干细胞移植最严重的并发症 尽管常规免疫，但在所有HSCT接受者中约有50%发生 预防。GVHD是由成熟的同种异体反应性供体来源的T细胞介导的，这些T细胞在移植物中存在， 移植的时间，并最终造成组织损伤。在GVHD的急性期， 发生在移植后的前100天，炎症仅限于有限数量的靶器官， 特别是皮肤、肝脏和胃肠道（GI）。GVHD对胃肠道的损害是一个特别重要的因素， 导致显著发病率和死亡率的严重事件。促炎性细胞因子在 肠道GVHD的病理生理学通过激活免疫系统的先天和适应性武器。 虽然T细胞是GVHD的最接近驱动因素，但疾病诱导和扩增依赖于这种串扰 先天免疫细胞和适应性免疫细胞之间的区别。然而，介导这一过程的细胞和细胞因子网络 相互作用没有完全理解。使用良好表征的GVHD小鼠模型的初步研究 已经鉴定出GM-CSF是一种细胞因子，其由GI中的供体来源的CD4 + T细胞以高水平产生 移植物抗宿主病时的尿道此外，CD4 + T细胞中GM-CSF信号转导的破坏显著降低了CD4 + T细胞的存活率。 小鼠受体经历GVHD，并减少炎症损伤的结肠，表明这一点， 细胞因子在GVHD生物学中起重要作用。根据这些研究，这一总体假设 建议GM-CSF通过下游激活促进胃肠道炎症 增强T细胞同种异体反应性的先天免疫群体。具体目标1的研究将 确定GM-CSF反应性髓样细胞群，其在胃肠道中介导炎症， GVHD。这一目标将采用新的遗传和抗体为基础的方法，以确定相关的GM-CSF， 依赖的先天免疫群体，并将决定这些细胞介质如何能够直接 会导致炎症具体目标2中的研究将通过以下方式定义机制途径： 其中GM-CSF调节GVHD中的T细胞同种异体反应性。这些实验将研究GM-CSF如何影响 供体来源的抗原呈递细胞（APC）产生白细胞介素-23，一种细胞因子， 已被证明是至关重要的诱导胃肠道炎症在移植物抗宿主病，确定如何GM- APC中的CSF信号传导影响胃肠道中的间接同种抗原呈递，并表征GM-CSF如何 调节调节性T细胞区室的重建。本建议的总体目标是 为胃肠道内GVHD的病理生理学和调节提供了新的见解， 发展临床相关策略以减轻同种异体HSCT受者的这种并发症。

PROJECT SUMMARY Graft-versus-host disease (GVHD) is the most serious complication of allogeneic hematopoietic stem cell transplantation (HSCT) and occurs in approximately 50% of all HSCT recipients despite routine immune prophylaxis. GVHD is mediated by mature alloreactive donor-derived T cells, which are present in the graft at the time of transplant and ultimately cause tissue damage. During the acute phase of GVHD, which typically occurs in the first 100 days post-transplantation, inflammation is restricted to a limited number of target organs, specifically the skin, liver, and gastrointestinal (GI) tract. Damage to the GI tract from GVHD is a particularly serious event leading to significant morbidity and mortality. Proinflammatory cytokines play a critical role in the pathophysiology of intestinal GVHD by activating both the innate and adaptive arms of the immune system. While T cells are the proximate drivers of GVHD, disease induction and amplification rely on this crosstalk between innate and adaptive immune cells. However, the cellular and cytokine networks which mediate this interplay are incompletely understood. Preliminary studies using well-characterized murine models of GVHD have identified GM-CSF as a cytokine which is produced at high levels by donor-derived CD4+ T cells in the GI tract during GVHD. Moreover, disruption of GM-CSF signaling in CD4+ T cells significantly prolongs survival in murine recipients undergoing GVHD and reduces inflammatory damage to the colon, indicating that this cytokine plays an important role in GVHD biology. Based on these studies, the overall hypothesis of this proposal is that GM-CSF promotes inflammation in the GI tract via the downstream activation of innate immune populations that potentiate T cell alloreactivity. Studies in Specific Aim 1 will determine the GM-CSF responsive myeloid cell populations that mediate inflammation in the GI tract during GVHD. This aim will employ novel genetic and antibody-based approaches to identify the relevant GM-CSF- dependent innate immune populations and will determine how these cellular mediators are able to directly contribute to the proinflammatory milieu. Studies in Specific Aim 2 will define the mechanistic pathways by which GM-CSF modulates T cell alloreactivity in GVHD. These experiments will examine how GM-CSF affects the production of interleukin-23 by donor-derived antigen presenting cells (APCs), a cytokine that has previously been shown to be crucial for the induction of gastrointestinal inflammation during GVHD, determine how GM- CSF signaling in APCs affects indirect alloantigen presentation in the GI tract, and characterize how GM-CSF modulates reconstitution of the regulatory T cell compartment. The overall objective of this proposal is to provide new insights into the pathophysiology and regulation of GVHD within the GI tract that will foster the development of clinically relevant strategies to mitigate this complication in allogeneic HSCT recipients.