Reflux-Induced Epithelial-Mesenchymal Transition in Benign Barrett's Esophagus

项目摘要 据估计，5.6%的美国成年人患有巴雷特食道(BE)，这是患食管炎的主要危险因素 食管腺癌。为了预防这种癌症，建议BE患者定期进行内窥镜检查。 监测不典型增生，并对其进行射频消融(RFA)治疗。不幸的是， 监测未能阻止死于食道癌，巴雷特的化生在之后经常复发 RFA。监测失败和化生复发可能是由于鳞状下肠化生。 (SSIM)，化生性腺体位于固有层鳞状细胞下的一种情况 将它们隐藏起来不让内窥镜医生看到并保护它们免受RFA破坏的上皮细胞。Ssim最初是 被认为是内窥镜消融的副作用，但最近的研究表明，SSIM存在于绝大多数情况下。 没有做过消融手术的巴雷特的病人。这种高度流行的SSIM可能是 内窥镜监测漏诊肿瘤，RFA术后复发化生的病灶。于是，Ssim应运而生。 是一种频繁而重要的疾病，限制了数百万人的内窥镜监测的有效性 BE患者，这阻碍了内窥镜根除BE并防止其发展为癌症的努力。 上皮-间充质转化(EMT)是上皮细胞获得间质的过程 包括细胞迁移在内的特征。在BE中，EMT可以使化生的Barrett上皮细胞迁移 进入邻近鳞状上皮下的固有层，导致SSIM。在我们的大鼠模型中 我们通过建立食道空肠吻合术来诱发反流性食管炎，我们的初步数据强烈表明 溃疡食道鳞状黏膜旁的空肠上皮细胞接受EMT，这有助于 具有Barrett‘s化生包括SSIM的特征的柱状衬里食道的发展。 胃食道反流会导致食管炎和产生活性氧物质， 能够激活低氧诱导因子(HIF)的条件。我们的初步数据显示巴雷特上皮细胞 暴露于酸和胆盐中的细胞表现出核内HIF-1α和HIF-2α的强烈而持续的增加。在……里面 BE患者巴氏化生中的低氧诱导因子-1α和低氧诱导因子-2α水平在 食道内充满了酸或胆盐。HIFs通过使细胞分泌血管而促进EMT 内皮生长因子(VEGF)，它以自分泌的方式结合细胞的VEGF受体，以诱导 触发EMT的血管内皮生长因子信号。我们的初步数据显示，酸和胆盐诱导自分泌血管内皮生长因子 巴雷特细胞系的信号和EMT特征。因此，我们假设，回流诱导的激活 Barrett‘s上皮细胞中的HIF通过自分泌的血管内皮细胞生长因子信号引起血管内皮生长因子的分泌，从而启动内皮细胞转化 程序并导致SSIM。本研究旨在阐明胃酸和胆汁的作用机制(S)。 盐激活HIF导致血管内皮细胞生长因子的产生，并探讨自分泌血管内皮生长因子信号在子宫内膜癌中的作用 酸和胆盐在体外诱导Barrett细胞和BE反流性食管炎患者的程序。

Project Summary It has been estimated that 5.6% of adult Americans have Barrett’s esophagus (BE), a major risk factor for esophageal adenocarcinoma. To prevent this cancer, patients with BE are advised to have regular endoscopic surveillance for dysplasia, and to have that dysplasia treated with radiofrequency ablation (RFA). Unfortunately, surveillance has not prevented deaths from esophageal cancer, and Barrett’s metaplasia recurs frequently after RFA. Surveillance failures and metaplasia recurrences might be due to subsquamous intestinal metaplasia (SSIM), a condition in which metaplastic glands are located in the lamina propria under a layer of squamous epithelium that hides them from the endoscopist and shields them from destruction by RFA. SSIM initially was considered a side effect of endoscopic ablation, but recent studies show that SSIM is present in the large majority of Barrett’s patients who have not had ablation procedures. This highly prevalent SSIM might be the source of tumors missed by endoscopic surveillance, and the nidus for recurrent metaplasia after RFA. Thus, SSIM appears to be a frequent and important condition that limits the efficacy of endoscopic surveillance for the millions of patients with BE, and that thwarts endoscopic attempts to eradicate BE and prevent its progression to cancer. Epithelial-mesenchymal transition (EMT) is the process in which epithelial cells acquire mesenchymal characteristics including cell migration. In BE, EMT could enable metaplastic Barrett’s epithelial cells to migrate into the lamina propria underneath adjacent squamous epithelium, resulting in SSIM. In our rat model in which we induce reflux esophagitis by creating an esophago-jejunostomy, our preliminary data strongly suggest that jejunal epithelial cells adjacent to ulcerated esophageal squamous mucosa undergo EMT, which contributes to the development of a columnar-lined esophagus with features of Barrett’s metaplasia including SSIM. Gastroesophageal reflux causes esophageal inflammation and production of reactive oxygen species, conditions that can activate hypoxia inducible factors (HIFs). Our preliminary data show that Barrett’s epithelial cells exposed to acid and bile salts exhibit a strong and sustained increase in nuclear HIF-1α and HIF-2α. In patients with BE, we also show that HIF-1α and HIF-2α levels in their Barrett’s metaplasia rise when the esophagus is perfused with acid or bile salts. HIFs can promote EMT by causing cells to secrete vascular endothelial growth factor (VEGF), which binds the cells’ VEGF receptors in an autocrine fashion to induce VEGF signaling that triggers EMT. Our preliminary data show that acid and bile salts induce autocrine VEGF signaling and EMT features in Barrett’s cell lines. Therefore, we hypothesize that reflux-induced activation of HIFs in Barrett’s epithelial cells causes VEGF secretion with autocrine VEGF signaling, which initiates the EMT program and causes SSIM. The aims of this study are to elucidate the mechanism(s) whereby acid and bile salts activate HIFs to cause VEGF production, and to explore the role of autocrine VEGF signaling in the EMT program induced by acid and bile salts in Barrett’s cells in vitro, and in BE patients with reflux esophagitis.