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

描述(申请人提供)：克罗恩病(CD)的免疫发病机制的特征是对肠道微生物群的天然和适应性免疫反应的免疫调节缺陷，导致无法控制的炎性T辅助细胞(Th)1和Th17反应，其机制尚不清楚。尽管已提出通过MyD88依赖的Toll样受体(TLRs)激活专业抗原提呈细胞(APC)的致炎机制，但取消专业APC的致病反应只会显著改善CD动物模型的肠道平衡，而不是完全恢复。这种不完全的反应提出了一个问题：非专业的APC，如肠道固有层中丰富的CD90+基质细胞，在这些过程中扮演着什么角色？我们的目的是确定人结肠粘膜CD90+基质细胞(肌成纤维细胞/成纤维细胞，CMF)中TLR依赖和独立的信号传递过程如何参与调节Th1/Th17肠道平衡，并确定这些过程在CD中是如何被破坏的。我们的中心假设是CD90+(Myo)成纤维细胞功能从免疫抑制(IL-6lowPD-L1+)向炎症(IL-6HighPD-L1low)转变是CD中Th1/Th17反应持续的关键过程。这一假说的基本原理是，正常的(N-)CD90+CMF通过PD-L1(程序性细胞死亡1配体1)抑制不良的Th1型急性炎症，并刺激CD4+调节性T细胞的产生。相反，我们的数据表明CD-CMF的表型发生了根本的变化：它们低表达Th1抑制分子PD-L1，产生CD4+调节性T细胞的能力降低，基础和TLR诱导的IL-6分泌上调，aTh17促进细胞因子。我们使用成纤维细胞特异性MyD88条件性基因敲除小鼠的初步体内数据也支持CMF在调节Th1/Th17反应中的重要性。我们将通过以下具体目标来验证我们的假设：(1)明确人CD-CMF的致炎激活在调节Th1/Th17反应中的作用；(2)阐明CD-CMF的炎性(PD-L1lowIL-6高)激活的机制(S)；(3)确定CMF的炎症激活在CD小鼠结肠炎发展中的病理生理作用。这个项目意义重大 关于IBD的综合全球研究重点：它将阐明先天免疫和获得性免疫成分之间先前未被探索的相互作用，这些相互作用有助于CD的启动和发展。我们期望对CMF在CD免疫发病过程中调节Th1/Th17反应中的作用提供关键的机械性见解。作为一个翻译项目，我们希望为CD的有效治疗确定新的治疗靶点。

DESCRIPTION (provided by applicant): 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, plays 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.