干预tRNA衍生片段tRF-35-P4R8YP9LON4VN1调控II型上皮-间质转化关键环路抑制克罗恩病肠壁纤维化的机制研究

Back to the basic medical background for stenosis disease behavior as therapeutic difficulty in Crohn's disease, in addition to the role of chronic inflammation in the process of the disease, more importantly, there is also a self-reinforcing system of the intestinal wall fibrosis independent of the mechanism of chronic inflammation. This project is based on the critical point of the discovery in the preliminary work that tRNA-derived fragment (tRF-35-P4R8YP9LON4VN1) may be involved in key loop of intestinal fibrosis associated type II epithelial-mesenchymal transition dynamic equilibrium. The axis for change of tRNA-derived fragment→miR-200b-ZEB1/2 loop expression change or modification abnormality→interaction with TGFβ1-SMAD pathway modification→type II epithelial-mesenchymal transition to mesenchymal phenotype shift→intestinal fibrosis exacerbates is analyzed preliminarily. The basic research strategy to maintain the balance of type II epithelial-mesenchymal transition and block the process of intestinal fibrosis are established from the brand new perspective of reversing the abnormality of tRNA-derived fragments. The aim of this project is to provide a new insight into the potential biomarkers for predicting the stricture of Crohn's disease and to obtain the drug targets to inhibit the fibrotic obstruction in the intestine.

追溯狭窄型疾病行为成为克罗恩病治疗难点的基础医学背景，与之对应的除了疾病进程中慢性炎症因素的反复作用，更重要的是还存在独立于慢性炎症机制以外的肠壁纤维化自我增强体系。本项目基于前期工作中发现的tRNA衍生片段tRF-35-P4R8YP9LON4VN1可能参与克罗恩病肠壁纤维化相关II型上皮-间质转化动态平衡关键环路这一立足点，通过初步分析克罗恩病可能存在的tRNA衍生片段改变→miR-200b-ZEB1/2环路表达或修饰异常→与TGFβ1-SMAD通路交互作用改变→II型上皮-间质转化向间质表型偏移→肠壁纤维化加剧这一作用轴，继而从逆转tRNA衍生片段异常的全新角度，构建维系II型上皮-间质转化平衡、阻断肠壁纤维化进程的基础研究策略，为探究预测克罗恩病肠道纤维性狭窄的潜在生物标志物、获取抑制克罗恩病肠道纤维性梗阻的药物靶点提供新的启迪。

肠道纤维性狭窄作为克罗恩病严重的并发症之一，至今尚缺乏有效的治疗手段。而针对克罗恩病患者中存在的炎症反应的治疗手段对于其疾病进展中出现的肠壁纤维化并没有明显的延缓或是改善。本课题立足于通过克罗恩病独立于慢性炎症机制以外的通路抑制肠壁纤维化进程这一全新基点，从tRNA衍生片段改变的全新角度切入克罗恩病II型上皮-间质转化关键环路稳态机制的研究，探寻逆转tRF异常阻断II型上皮-间质转化抑制克罗恩病肠壁纤维化策略的可行性。本课题首先将克罗恩病肠壁纤维化进程慢性炎症机制和独立于慢性炎症机制以外的自我增强机制结合，依托tRF高度的组织特异性和时序特异性探讨tRNA衍生片段tRF-35-P4R8YP9LON4VN1成为克罗恩病预测肠道纤维性梗阻潜在指示标志的可能性。其次，本课题确定了克罗恩病存在tRNA衍生片段tRF-35-P4R8YP9LON4VN1表达改变（增高）→miR-200b-ZEB2环路异常→与TGFβ1-SMAD通路交互作用改变→E-cadherin/Cytokeratin 8表达抑制、Vimentin/αSMA/FSP1/N-cadherin表达增强→II型上皮-间质转化向间质表型偏移→肠壁纤维化加剧这一作用途径，途径中的关键节点可能为miR-200b。最后，本研究对调控tRNA衍生片段tRF-35-P4R8YP9LON4VN1阻断II型上皮-间质转化关键环路抑制克罗恩病肠壁纤维化策略进行逆转分析，进而阐明了tRNA衍生片段tRF-35-P4R8YP9LON4VN1作为抑制克罗恩病肠壁纤维化梗阻潜在药物治疗靶点的可能性。总之，本课题通过确定克罗恩病中存在tRNA衍生片段tRF-35-P4R8YP9LON4VN1表达增高通过miR-200b-ZEB2环路表达或修饰异常导致II型上皮-间质转化向间质表型偏移加剧肠壁纤维化这一作用途径及其具体作用机制，一定程度上验证了tRF-35-P4R8YP9LON4VN1成为克罗恩病预测肠道纤维性狭窄潜在指示标志的可能性，提示tRNA衍生片段tRF-35-P4R8YP9LON4VN1作为抑制克罗恩病肠壁纤维化潜在药物治疗靶点的可能性，进而为克罗恩病肠壁纤维性狭窄现有治疗手段提供了补充方法。