肠壁纤维化是克罗恩病（Crohn's disease, CD）治疗中实现粘膜功能性修复的最大障碍,现有治疗手段均无法阻止肠壁纤维化。动物及临床研究提示间充质干细胞（MSCs）移植可有效治疗CD，有望实现功能性修复，但其作用受微环境影响。我们前期研究发现CD患者肠MSCs存在自我增殖及免疫调节异常，其局部微环境不适合MSCs获取治疗所需的功能状态。如何诱导活化MSCs发挥粘膜修复及抗纤维化作用是MSCs移植治疗CD的关键技术问题。我们在动物模型体内证实，TLRs配体极化后的MSCs抗炎及抗纤维化细胞因子上调，显著改善症状及组织学评分，并诱导CD4+T细胞向Treg细胞分化，但机制不明。本项目拟从体外细胞学及动物体内研究阐明TLRs配体活化后MSCs如何发挥更可控的促粘膜愈合及促非纤维化修复作用；同时探索TLRs-Jagged1-Notch信号通路的可能作用，为实现CD粘膜功能性修复奠定基础。

Intestinal fibrosis represents the biggest challenge for the functional healing of intestinal mucosal barrier injured in Crohn's disease. Till now, the available treatment tools could not prevent or reverse intestinal fibrosis. It has been proven both in animal model and clinical trial, mesenchymal stem cells (MSCs) with immune regulatory and regenerative functions, may serve as an effective treatment strategy for CD, with the promising of promoting function repair. However, the function of MSCs mainly depends on the surrounding microenvironment. Our preliminary study has found that intestinal mesenchymal stem cells isolating from CD patients demonstrate abnormal self-proliferation and immunomodulatory capacity when compared with normal controls. The intestinal microenvironment of CD patients may not be suitable to prime and polarize MSCs to the required functional status. Thus how to prime MSCs in vitro to exert the function of mucosal healing and anti-fibrosis in vivo may represent the key technique problem when applied in the treatment of CD. We further confirmed that in vivo TNBS-induced intestinal colitis animal models, TLRs ligands priming entailed MSCs more powerful immunomodulatory functions, ameliorated both symptomatic and historical scores, and induced the differentiation of T cells from colitis mesenteric lymph nodes into Treg. However, the attributing mechanism is still unknown, which may partly be due to the secretion of anti-inflammatory and anti-fibrosis cytokines. And whether such polarized MSCs following TLR ligands priming may vary the naive MSCs for functional healing of injured mucosal of CD has not been reported. In the present study, we plan to explore the role of differential priming MSCs with TLRs ligands for the functional healing of intestinal mucosal barrier injured in CD. The main contents include: (1) to explore whether polarized MSCs is more controllable than the naive MSCs for promoting functional (non-fibrotic) healing of chronic injured mucosal barrier by cytology in vitro and in vivo animal studies; (2) to explore the potential role of signaling pathway of TLR3/4-Jagged-1-Notch. In this study, in new point of view of differential priming MSCs through TLRs ligands, we aim to lay the foundation for functional healing of injured mucosa of CD.