A Novel Role of DRA in IBD Pathogenesis

项目总结/摘要 炎症性肠病（IBD）是一种全球健康负担，目前影响着全球约300万人。 美国，全球发病率不断上升。根据最近的一份报告， 美国退伍军人在过去十年中迅速增加。尽管所有的进展，IBD的发病机制 由于疾病的多因素性质和治疗选择不充分，目前尚不清楚。 因此，了解IBD的分子病理生理学对于开发有效的治疗药物至关重要。 方式。几种不同的机制可能解释IBD的发病机制。在这方面，妥协 肠屏障是IBD中与肠道炎症发作相关的最关键的早期事件之一。 最近的研究表明，上皮离子转运蛋白（如NHE3和CFTR）在维持细胞增殖中发挥着新的作用。 屏障完整性在这方面，SLC26A3（Down Regulated in Adenoma或SLC26A3）是关键的转运蛋白。 介导哺乳动物肠道中的氯化物吸收。ESTK0小鼠表现出缺乏粘附的内 粘液层，改变结肠隐窝的增殖动态平衡，并且更容易受到实验性 结肠炎GWAS进一步证明了RP4在炎症中的重要作用，将RP4作为一种新的 IBD易感基因此外，在人IBD患者结肠粘膜和人IBD患者结肠粘膜中， 再现IBD的小鼠模型。然而，这种增加易感性的机制， 炎症反应的损失是未知的，并保证详细的调查。我们 初步的数据提供了强有力的证据，证明了Escherichia coli在维持上皮完整性方面的新作用。我们 初步数据表明，在通过多种途径破坏上皮屏障中， 机制，例如通过直接影响TJ/AJ和/或通过间接（与其Cl-/HCO3-交换有关） 功能、其细胞骨架相互作用和/或微生物生态失调）。此外，通过上调 似乎是恢复屏障功能和减轻炎症的新的治疗方法。然而，在这方面， 在临床前模型中，靶向血管内皮细胞以恢复屏障功能的治疗可行性从未被 研究了因此，我们假设：i）胰岛素丢失通过减少TJ扰乱肠屏障功能， AJ蛋白通过涉及RNA结合蛋白的转录后机制和/或通过直接的 与细胞骨架元素的相互作用。ii）上调HSP70功能和表达可以减轻 通过恢复肠屏障功能来治疗炎症。我们的假设将用最先进的 方法和人/小鼠类结肠、Caco-2细胞和KO或转基因小鼠模型。两个具体 目标1：目标1。阐明调控肠道屏障的转录后机制 功能和TJ/AJ蛋白质响应于β-内酰胺酶缺乏;和目的2.阐释了小说中的人物 实验性肠上皮细胞完整性和紧密连接蛋白的上调 来自健康和IBD患者的结肠炎和类结肠模型。这些成功的结果 研究应该对肠道TJ/AJ调节的分子机制产生重要的见解，并建立 作为一种新的治疗靶点来管理IBD。此外，这些研究将为申请人提供一个伟大的 成为膜氯化物新作用机制专家的培训工具 肠紧密连接转运蛋白失调和IBD发病机制，以及培养他在切割- 边缘方法利用肠，结肠和先进的成像技术，使他成为一个 独立的VA调查员专注于IBD研究。

Project Summary/Abstract Inflammatory Bowel Disease (IBD) is a global health burden currently affecting around 3 million people in the United States with increasing incidence worldwide. According to a recent report, prevalence of IBD among US veterans rapidly increased during the past decade. Despite all the advancement, pathogenesis of IBD is still unclear due to the multifactorial nature of the disease and the treatment options are not adequate. Therefore, understanding the molecular pathophysiology of IBD is critical for developing effective therapeutic modalities. Several different mechanisms likely account for the IBD pathogenesis. In this regard, compromised Intestinal barrier is one of the most critical early event linked to the onset of intestinal inflammation in IBD. Recent studies have implicated novel roles of epithelial ion transporters (e.g. NHE3 and CFTR) in maintaining barrier integrity. In this regard, DRA (Down Regulated in Adenoma or SLC26A3) is the key transporter mediating chloride absorption in the mammalian intestine. DRA KO mice exhibit lack of an adherent inner mucus layer, altered proliferative homeostasis of the colonic crypts, and are more susceptible to experimental colitis. The important role of DRA in inflammation is further evident from GWAS, identifying DRA as a novel IBD susceptibility gene. Further, DRA levels are severely depleted in human IBD patient colonic mucosa and in mouse models recapitulating IBD. However, the mechanisms underlying this increased susceptibility to inflammation in response to loss of DRA are not known and warrant detailed investigations. Our preliminary data provide strong evidence for a novel role of DRA in maintenance of epithelial integrity. Our preliminary data suggest that loss of DRA may play a key role in breaching the epithelial barrier via multiple mechanisms e.g. either by directly affecting the TJ/AJ and/or via indirect (related to its Cl-/HCO3- exchange function, its cytoskeletal interactions and/or microbial dysbiosis). In addition, targeting DRA via its upregulation appears to be a novel therapeutic approach to restore barrier function and alleviating inflammation. However, the therapeutic feasibility of targeting DRA to restore barrier function in preclinical models has never been investigated. Therefore, we hypothesize that i) DRA loss perturbs intestinal barrier function by reducing TJ and AJ protein expression via posttranscriptional mechanisms involving RNA binding proteins and/or via direct interactions with cytoskeletal elements. ii) Upregulation of DRA function and expression can alleviate inflammation via restoration of intestinal barrier function. Our hypothesis will be tested utilizing state-of-the-art approaches and human/mouse colonoids, Caco-2 cells and KO or transgenic mouse models. Two Specific Aims have been proposed: Aim 1. Elucidate the post-transcriptional mechanisms modulating gut barrier function and TJ/AJ proteins in response to DRA deficiency; and Aim 2. Elucidate the novel role of DRA upregulation in maintenance of intestinal epithelial integrity and tight junction proteins in experimental models of colitis and colonoids derived from healthy and IBD patients. Successful outcome of these studies should yield critical insights into the molecular mechanisms of intestinal TJ/AJ regulation and establish DRA as a novel therapeutic target to manage IBD. Additionally, these studies will provide the applicant a great training vehicle for becoming an expert in mechanisms underlying the novel role of a membrane chloride transporter in intestinal tight junction dysregulation and pathogenesis of IBD, as well as train him in cutting- edge approaches utilizing enteroids, colonoids and advanced imaging techniques to evolve him into an independent VA investigator focused on IBD research.