HB-EGF and Intestinal Ischemia/Reperfusion

描述（由申请人提供）：尽管进行了数十年的研究，但我们对如何充分保护肠道免受缺血/再灌注（I/R）损伤后遗症的理解存在根本性差距。我们已经积累了多条证据表明，肝素结合EGF样生长因子（HB-EGF）可以保护肠I/R损伤。我们工作的长期目标是给予HB-EGF治疗，以保护肠道免受损伤。目前更新申请的总体目标是确定HB-EGF与干细胞（SC）相互作用的关键要素，这些要素可用于增强生长因子的活性。我们的中心假设是，HB-EGF的肠道细胞保护作用的显著比例是通过其对SC的作用介导的，并且HB-EGF与SC的相互作用可以增强以增加生长因子的功效。其基本原理是，一旦HB-EGF与SC的相互作用得到更好的理解，就可以开发出治疗肠I/R损伤的最有益的创新方法。我们将通过以下具体目标客观地检验我们的中心假设：目的1）确定HB-EGF在保护肠SC（ISC）免受损伤中所利用的信号传导机制和受体。我们将使用高度纯化的ISC来确定HB-EGF对这些细胞中Wnt、BMP、PI3K和Notch信号通路的影响。目的2）探讨内源性HB-EGF表达对损伤后ISC扩增和分化的影响。我们将使用一种新的离体隐窝-绒毛类器官培养系统和在体肠I/R损伤模型来研究HB-EGF对ISC扩增和分化的影响。目的3）研究骨髓源性SC是否能增强HB-EGF介导的肠道保护作用。我们将确定SC动员或给药与HB-EGF给药结合在体内保护肠免受I/R损伤中的作用。我们的研究结果预计将在为肠I/R损伤患者提供改善的治疗干预方面产生重要的积极影响，此外还将从根本上促进对肠道中生长因子/SC相互作用的理解。这一贡献是重要的，因为它将使我们能够最好地利用临床HB-EGF治疗的潜力。拟议的研究是创新的，因为我们寻求将目前的肠I/R损伤实验疗法从单一炎症介质的靶向转移到旨在保护和再生肠粘膜的策略，通过给予肠细胞保护生长因子与多能SC。

DESCRIPTION (provided by applicant): Despite decades of research, there is a fundamental gap in our understanding of how to adequately protect the intestines from the sequellae of ischemia/reperfusion (I/R) injury. We have accumulated multiple lines of evidence demonstrating that heparin-binding EGF-like growth factor (HB-EGF) can protect the intestines from I/R injury. The long-term goal of our work is to administer HB-EGF therapeutically to protect the intestines from injury. The overall objective of the current renewal application is to identify key elements of the interaction of HB- EGF with stem cells (SC) that may be utilized to augment the activity of the growth factor. Our central hypothesis is that a significant proportion of the intestinal cytoprotective effects of HB- EGF are mediated through its effects on SC, and that the interaction of HB-EGF with SC can be augmented in order to increase the efficacy of the growth factor. The rationale is that once the interactions of HB-EGF with SC are better understood, maximally beneficial innovative approaches to the treatment of intestinal I/R injury can be developed. We will objectively test our central hypothesis by pursuing the following specific aims: Aim 1) to determine the signaling mechanisms and receptors utilized by HB-EGF in protecting intestinal SC (ISC) from injury. We will use highly purified ISC to determine the effects of HB-EGF on the Wnt, BMP, PI3K and Notch signaling pathways in these cells. Aim 2) to determine whether endogenous HB-EGF expression affects ISC expansion and differentiation after injury. We will use a novel ex vivo crypt-villous organoid culture system and an in vivo intestinal I/R injury model to investigate the effects of HB-EGF on ISC expansion and differentiation. Aim 3) to determine whether bone marrow (BM)-derived SC can improve HB-EGF-mediated protection of the intestines from injury. We will determine the effects of SC mobilization or administration, in conjunction wth HB-EGF administration, in protection of the intestines from I/R injury in vivo. The results of our studies are expected to have an important positive impact in terms of providing improved therapeutic interventions for patients suffering from intestinal I/R injury, in addition to fundamentally advancing the understanding of growth factor/SC interactions in the intestines. This contribution is significant because it will enable us to best exploit the potential of clinical HB-EGF therapy. The proposed research is innovative because we seek to shift current experimental therapies for intestinal I/R injury away from the targeting of single inflammatory mediators, and towards strategies designed to protect and regenerate the intestinal mucosa, through administration of an intestinal cytoprotective growth factor in conjunction with multipotent SC.