Assessment of immune modulation by Notch signaling-exploration of immunomodulatory intervention targeting Notch system.

通过Notch受体的信号传导调节免疫系统的各个方面，例如胸腺中T细胞的发育、脾中边缘区B细胞的形成、Th 1/Th 2分化和T细胞活化的调节。因此，如果我们能够使用Notch信号的激动剂或拮抗剂来调节Notch信号，那么我们将能够建立一种新的技术来调节异基因造血干细胞移植后的免疫重建。本研究旨在获得基础数据，支持建立通过Notch信号调节预防移植物抗宿主病（GVHD）的方法。我们在MHC I类和MHC II类启动子下产生了表达野生型和显性阴性形式Notch配体的转基因小鼠，并表征了淋巴细胞的表型和功能。我们发现，T细胞活化的混合淋巴细胞培养显着减少在转基因小鼠表达野生型锯齿蛋白1，五个已知的Notch配体之一，在MHC II类启动子。使用这些小鼠作为急性GVHD、排斥和慢性GVHD模型中的供体和受体，正在进行同种异体移植实验。基于这些实验的结果，我们计划使用Notch激动剂和拮抗剂来研究单个Notch系统的调节如何影响GVHD的发展。此外，我们使用Notch 2条件性敲除小鼠发现Notch 2信号传导调节被认为对先天免疫重要的表面分子的表达。基于这一发现，我们目前正在研究通过Notch 2受体的信号传导如何在边缘区B细胞的T细胞非依赖性抗体产生中发挥作用。

Signaling through Notch receptors regulates various aspects of immune system, such as development of T cells in the thymus, formation of marginal zone B cells in the spleen, Th1/Th2 differentiation and regulation of T cell activation. Therefore, it is expected that we will be able to establish a new technology to regulate immune reconstitution after allogeneic hematopoietic stem cell transplantation if we can modulate Notch signaling using its agonists or antagonists. In this study, we aimed at obtaining basic data supporting establishment of a method to prevent graft-versus-host disease (GVHD) by Notch signaling modulation.We have generated transgenic mice expressing wild-type and dominant-negative form of Notch ligands under the MHC class I and MHC class II promoters, and characterized the phenotype and function of lymphocytes. We found that the T cell activation by the mixed lymphocyte culture was markedly reduced in the transgenic mice expressing wild-type Jagged1, one of the five known Notch ligands, under the MHC class II promoter. Using these mice as donors and recipients in the acute GVHD, rejection and chronic GVHD models, ongoing are allogeneic transplantation experiments. Based on the results deriving from these experiments, we plan to study, using Notch agonists and antagonists, how the modulation of individual Notch system affects development of GVHD.Furthermore, we found that Notch2 signaling regulates the expression of surface molecules which are considered to be important for the innate immunity, using Notch2 conditional knockout mice. Based on this finding, we are currently studying how the signaling through Notch2 receptor plays a role in the T cell-independent antibody production by the marginal zone B cells.