The role of secondary lymphoid organ fibroblastic cells in alloimmunity

项目总结/摘要 异基因骨髓移植（allo-BMT）可以治愈血液癌症和其他疾病，但有限 移植物抗宿主病（GVHD）。在清髓性预处理和异基因骨髓移植后，供体- 衍生的T细胞遇到外来组织抗原和其它关键信号， 和GVHD。到目前为止，我们对这些信号的理解仍然不完整。我们发现阿曲他克林 Delta-like 1/4（Dll 1/4）配体诱导的Notch信号是致死性GVHD的关键驱动因素。同种异体反应性T细胞 从脾和淋巴结中的非造血成纤维基质细胞接收Notch信号， 而不是来自造血抗原呈递细胞。Ccl 19-Cre+成纤维基质细胞中的Dll 1/4失活 在清髓性allo-BMT小鼠模型中保护受体免于致死性GVHD。但不清楚 清髓性预处理后成纤维基质细胞是否是GVHD发病机制所必需的 以及它们是否除了呈递Notch配体之外还可以作为同种异体抗原的细胞来源。整体 该计划的目的是研究成纤维基质细胞在T细胞免疫中的作用和调节，以及 探索它们作为GVHD和其他免疫疾病的治疗靶点的相关性。为了实现这一目标， 我们将在两个独立的目标中研究成纤维细胞免疫生物学的两个领域。目标1将评估如何 清髓性预处理影响成纤维基质细胞作为allo-BMT期间Notch配体的来源。我们 将研究分级强度的清髓性条件反射如何调节Notch配体表达， 成纤维基质细胞亚群和其他与供体T细胞相互作用的细胞群的可接近性。 我们将实时确定清髓性条件反射是否改变同种抗原特异性T细胞的行为 以及它们与宿主成纤维细胞和造血细胞的早期相互作用。使用临床相关的小鼠同种异体- BMT模型，我们将测试成纤维细胞是否仍然是驱动GVHD的Notch信号的关键致病源 即使条件减少或没有条件，这将表明在更广泛的豁免方面的关键功能。目的 2将测试成纤维基质细胞是否在GVHD期间作为同种异体抗原呈递细胞发挥作用。初步 有证据表明成纤维细胞基质细胞在同种异体移植后上调其抗原呈递机制， BMT。我们将研究驱动这种上调的信号，并使用遗传功能丧失的方法， 测试成纤维细胞内在MHC II类表达是否有助于GVHD发病机制。同时，我们将 使用活体成像研究同种抗原和Notch配体对早期相互作用的影响， 同种异体反应性T细胞、成纤维基质细胞和其他抗原呈递细胞在GVHD发作时。我的工作 有可能揭示成纤维基质细胞在GVHD中的新功能，并提示其在GVHD中的作用。 更广泛的免疫学背景。此外，它将为我提供结构化的学习机会， 实验免疫生物学，这是我作为一名免疫学家和物理学家的训练目标。

PROJECT SUMMARY/ABSTRACT Allogeneic bone marrow transplantation (allo-BMT) can cure blood cancers and other disorders, but is limited by life-threatening graft-versus-host-disease (GVHD). After myeloablative conditioning and allo-BMT, donor- derived T cells encounter foreign tissue antigens and other critical signals that induce pathogenic alloimmunity and GVHD. To date, our understanding of these signals remains incomplete. We discovered that juxtacrine Notch signals induced by Delta-like1/4 (Dll1/4) ligands are key drivers of lethal GVHD. Alloreactive T cells received Notch signals from non-hematopoietic fibroblastic stromal cells in the spleen and lymph nodes, but not from hematopoietic antigen-presenting cells. Dll1/4 inactivation in Ccl19-Cre+ fibroblastic stromal cells protected recipients from lethal GVHD in a mouse model of myeloablative allo-BMT. However, it is unknown whether fibroblastic stromal cells are essential for GVHD pathogenesis only after myeloablative conditioning and if they can function as a cellular source of alloantigens in addition to presenting Notch ligands. The overall goal of this proposal is to study the role and regulation of fibroblastic stromal cells in T cell immunity, as well as explore their relevance as therapeutic targets in GVHD and other immune disorders. To accomplish this goal, we will investigate two areas of fibroblastic cell immunobiology in two independent Aims. Aim 1 will assess how myeloablative conditioning affects fibroblastic stromal cells as sources of Notch ligands during allo-BMT. We will study how graded intensities of myeloablative conditioning regulate Notch ligand expression and accessibility in subsets of fibroblastic stromal cells and other cell populations that interact with donor T cells. We will determine in real-time if myeloablative conditioning changes the behavior of alloantigen-specific T cells and their early interactions with host fibroblastic and hematopoietic cells. Using clinically relevant mouse allo- BMT models, we will test if fibroblastic cells remain key pathogenic sources of Notch signals driving GVHD even with reduced or no conditioning, which would suggest key functions in broader aspects of immunity. Aim 2 will test if fibroblastic stromal cells function as alloantigen-presenting cells during GVHD. Preliminary evidence suggests that fibroblastic stromal cells upregulate their antigen presentation machinery after allo- BMT. We will investigate the signals that drive this upregulation and use genetic loss of function approaches to test if fibroblastic cell-intrinsic MHC Class II expression contributes to GVHD pathogenesis. In parallel, we will use intravital imaging to study the impact of alloantigens and Notch ligands on early interactions between alloreactive T cells, fibroblastic stromal cells and other antigen-presenting cells at the onset of GVHD. My work has the potential to uncover new functions of fibroblastic stromal cells in GVHD and to suggest a role in broader immunological contexts. In addition, it will provide me with structured learning opportunities in experimental immunobiology that serve my training goals as an immunologist and physician-scientist.