MicroRNA-21通过PTEN/Akt信号通路调节嗜酸细胞性食管炎组织纤维化的机制研究

Eosinophilic esophagitis (EoE) is a newly emerged GI disease featured with eosinophils predominated inflammation in the esophagus and presented with symptoms of esophageal dysfunctions such as dysphagia and food impaction. In the recent years, EoE is being recognized with the increasing frequency world widely. Some advanced EoE patients have the symptoms related to esophageal tissue fibrosis, but the underlying mechanism is still unclear. We have previously reported that, in a guinea pig model, initial ovalbumin (OVA) exposure causes sensitization and re-exposing the animal to OVA by aerosol inhalation induces EoE, then we prolonged the OVA-challenge period and found esophageal fibrotic tissue increased. Compared to naïve animals, the thickness of esophageal epithelium basal zone significantly increased, the expressions of tight-junction protein ZO-1 and Occludin decreased, the permeability of esophageal epithelium increased. All these features point to the mechanism of epithelial- mesenchymal transition (EMT). In another experiment, we found microRNA-21 mediates EMT of human hepatocytes (QSG-7701) via PTEN/Akt pathway. Others reported the expression of microRNA-21 increased in esophageal epithelium of EoE patients. Basically, we hypothesize microRNA-21 could mediate tissue fibrosis in EoE, the mechanism may relate to EMT via PTEN/Akt pathway. We designed a series of experiments, including immune-staining, Western blot and real-time PCR. We also plan to isolate the primary esophageal epithelium cells and perform some in vitro tests to discover the related signal pathways. Finally, we designed to measure the esophageal tissue fibrosis in treated animals with antagomir or agomir by optical coherence tomography. We anticipate providing some fundamental evidences for the basic research of esophageal tissue fibrosis.

嗜酸细胞性食管炎（EoE）是一种新发消化疾病，部分EoE患者可出现食管组织纤维化。在前期研究中，我们建立了卵清蛋白（OVA）诱导的EoE豚鼠模型，发现延长刺激时间可使食管纤维组织增生；EoE豚鼠食管的上皮组织基底层增厚、紧密连接蛋白表达下降、食管上皮通透性增高，提示食管组织发生了上皮细胞-间充质转化（EMT）。我们还发现，microRNA-21可以通过PTEN/Akt调节人肝细胞株（QSG-7701）发生EMT。研究显示，EoE患者食管上皮组织中microRNA-21表达上调。我们推测，microRNA-21参与调节EoE组织纤维化，其过程可能与EMT有关并通过PTEN/Akt发挥作用。本课题拟利用EoE食管组织纤维化动物模型，通过组织、细胞和分子生物实验阐明食管组织纤维化的机制，并采用microRNA分子靶向治疗技术及光学相干断层扫描成像技术评估食管组织纤维化病情，为其诊治提供理论依据。

在嗜酸细胞性食管炎等慢性疾病中，嗜酸性粒细胞浸润与组织重构关系密切，这种组织结构的变化常出现在食管上皮层及上皮下层，包括基底细胞增生，组织纤维化，上皮间充质转化，局部血管生成及平滑肌增生肥大。我们通过长时间的OVA致敏刺激可使小鼠食管中纤维组织含量增加，这为食管组织纤维化的研究奠定了实验基础。组织纤维化过程可与一系列的促纤维化因子及促血管生成因子有关，其中TGF-b被认为是引起嗜酸细胞性食管炎食管上皮细胞间充质转化，组织纤维化和平滑肌增生的主要调节因子。我们研究发现miR-21参与食管组织纤维化的过程与食管上皮细胞间充质转化有关，通过一系列细胞分子生物学试验及生物信息学检测，分析发现miR-21是通过TGF-b引起食管上皮细胞发生细胞间充质转化，该研究结果为通过miR-21防治食管组织纤维化提供理论支持，具有一定的临床应用前景。