Regulatory role of CD90+ stromal cells in Th1/Th17 activity in Crohn's Disease

. 项目总结/摘要 克罗恩病（CD）的免疫发病机制的特点是先天免疫调节缺陷， 和适应性免疫反应对肠道菌群，导致不受控制的炎症性T辅助细胞 细胞（Th）1和Th 17通过未知的机制应答。虽然促炎性激活 通过MyD 88依赖性Toll样受体（TLR）的专职抗原呈递细胞（APC）已经被发现是一种新的抗原呈递细胞。 提出的机制，废除致病反应的专业APC只会导致强有力的 CD动物模型中肠道平衡的改善，但不是完全恢复。这种不完全 回答提出了一个问题：非专业的APC，如CD 90+基质细胞，一种丰富的细胞， 肠道固有层中的细胞类型，在这些过程中发挥作用？我们的目标是确定TLR依赖性 人肠结肠粘膜CD 90+基质细胞中的独立信号传导过程 （肌成纤维细胞/成纤维细胞，CMF）参与调节Th 1/Th 17肠道平衡，并决定 这些过程是如何在CD中被破坏的。 我们的中心假设是，CD 90+（肌）成纤维细胞功能从免疫抑制功能的转变， PD-L1+（IL-6 lowPD-L1+）向炎症（IL-6 highPD-L1 low）的转化是持续性PD-L1表达的关键过程。 CD中的Th 1/Th 17应答。这一假设的基本原理是正常的（N-）CD 90 + CMFs抑制 通过PD-L1（程序性细胞死亡1配体1）介导的不期望的Th 1型急性炎症， 刺激CD 4+调节性T细胞的产生。相比之下，我们的数据表明，CD-CMFs显示出 表型根本改变：Th 1抑制分子PD-L1表达降低， 产生CD 4+调节性T细胞和上调基础和TLR诱导型IL-6分泌的能力，aTh 17 促进细胞因子。我们使用成纤维细胞特异性MyD 88条件性敲除小鼠的初步体内数据也 支持CMF在调节Th 1/Th 17应答中的重要性。我们将测试我们的假设， （1）确定人CD-CMF的促炎性活化在 Th 1/Th 17应答的调节;（2）阐明炎症（PD-1）的机制。 （3）确定CMF炎症激活对CD-CMFs的病理生理作用， CD小鼠结肠炎的发展。 该项目对IBD的全球综合研究优先事项具有重要意义：它将阐明以前 先天性和适应性免疫成分之间的未探索的相互作用有助于启动和 CD的发展我们希望提供关键的机制的见解CMFs的作用，在调节的 CD免疫发病机制中的Th 1/Th 17应答作为一个翻译项目，我们希望确定新的 有效治疗CD的治疗靶点。

. PROJECT SUMMARY/ABSTRACT The immunopathogenesis of Crohn's Disease (CD) is characterized by defective immunoregulation of innate and adaptive immune responses toward intestinal microflora, leading to uncontrolled inflammatory T helper cell (Th)1 and Th17 responses via a yet unknown mechanism. Although the proinflammatory activation of professional antigen presenting cells (APCs) thorough MyD88-dependent toll like receptors (TLRs) has been proposed as the mechanism, abrogation of pathogenic responses of professional APCs leads only to a strong improvement, but not full restoration, of the intestinal balance in animal models of CD. This incomplete response raises the question: what role do non-professional APCs such as CD90+ stromal cells, an abundant cell type in the gut lamina propria, play in these processes? Our objective is to identify how TLR-dependent and independent signaling processes in human intestinal colonic mucosal CD90+ stromal cells (myofibroblasts/fibroblasts, CMFs) are involved in the regulation of Th1/Th17 intestinal balance, and determine how these processes are disrupted in CD. Our central hypothesis is that a switch in the CD90+ (myo)fibroblast function from immunosuppressive (IL-6lowPD-L1+) toward inflammatory (IL-6highPD-L1low) is a key process in the persistence of the Th1/Th17 responses in CD. The rationale for this hypothesis is that normal (N-) CD90+ CMFs suppress undesirable Th1 type acute inflammation mediated via PD-L1 (Programmed cell death 1 ligand 1) and stimulate the generation of CD4+ regulatory T cells. In contrast, our data suggest that CD-CMFs display a fundamentally altered phenotype: they have low expression of Th1 suppressive molecule PD-L1, reduced ability to generate CD4+ regulatory T cells and upregulated basal and TLR inducible IL-6 secretion, aTh17 promoting cytokine. Our initial in vivo data with use of fibroblast-specific MyD88 conditional knockout mice also support the importance of CMFs in the regulation of the Th1/Th17 responses. We will test our hypothesis by addressing the following specific aims: (1) Define role of the proinflammatory activation of human CD-CMFs in the regulation of Th1/Th17 responses; (2) Elucidate mechanism(s) responsible for the inflammatory (PD- L1lowIL-6high) activation of CD-CMFs; (3) Determine the pathophysiological role CMF inflammatory activation to the development of CD murine colitis. This project is highly significant to the integrative global research priorities in IBD: it will elucidate previously unexplored interactions between innate and adaptive immune components contributing to the initiation and progression of CD. We expect to provide key mechanistic insights into the role of CMFs in regulation of the Th1/Th17 responses during CD immunopathogenesis. As a translational project, we expect to identify new therapeutic targets for effective treatments of CD.