HB-EGF and Intestinal Ischemia/Reperfusion

描述（由申请人提供）：尽管经过数十年的研究，我们对如何充分保护肠道免受缺血/再灌注（I/R）损伤的后遗症的理解存在根本性的差距。我们已经积累了多条证据，证明肝素结合的egf样生长因子（HB-EGF）可以保护肠道免受I/R损伤。我们工作的长期目标是治疗性地施用HB-EGF以保护肠道免受损伤。当前更新申请的总体目标是确定HB- EGF与干细胞（SC）相互作用的关键因素，这些因素可能被用来增强生长因子的活性。我们的中心假设是，HB-EGF的肠细胞保护作用的很大一部分是通过其对SC的作用来介导的，并且HB-EGF与SC的相互作用可以增强，以提高生长因子的功效。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验证我们的中心假设：目的1)确定HB-EGF保护肠SC （ISC）免受损伤的信号机制和受体。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)确定内源性HB-EGF表达是否影响损伤后ISC的扩增和分化。我们将使用一种新的离体隐绒毛类器官培养系统和体内肠I/R损伤模型来研究HB-EGF对ISC扩增和分化的影响。目的3)确定骨髓（BM）源性SC是否可以改善hb - egf介导的肠道损伤保护。我们将确定SC动员或给药，结合HB-EGF给药，在体内保护肠道免受I/R损伤的作用。我们的研究结果预计将在为肠道I/R损伤患者提供改进的治疗干预方面产生重要的积极影响，并从根本上推进对肠道中生长因子/SC相互作用的理解。这一贡献意义重大，因为它将使我们能够最好地开发临床HB-EGF治疗的潜力。该研究具有创新性，因为我们试图将目前针对肠道I/R损伤的实验疗法从单一炎症介质的靶向转变为旨在保护和再生肠道黏膜的策略，通过施用肠道细胞保护生长因子与多能SC相结合。

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. PUBLIC HEALTH RELEVANCE: The proposed research is relevant to public health because it is expected to lead to a novel therapeutic strategy that will decrease morbidity and mortality related to intestinal I/R injury. The innovative approach to intestinal I/R injury that is proposed will lead to substantive improvements in clinical outcomes at the bedside, which is consistent with the mission of the NIH.