HB-EGF and Intestinal Ischemia/Reperfusion

描述(申请人提供)：尽管经过了几十年的研究，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着根本的差距。我们已经积累了多条证据表明，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从治疗的角度使用HB-EGF来保护肠道免受损伤。目前更新申请的总体目标是确定HB-EGF与干细胞(SC)相互作用的关键元素，这些元素可用于增强生长因子的活性。我们的中心假设是，很大一部分HB-EGF的肠道细胞保护作用是通过其对SC的影响而介导的，并且HB-EGF与SC的相互作用可以增强，以增加生长因子的疗效。其基本原理是，一旦更好地了解了HB-EGF与SC的相互作用，就可以开发出治疗肠道I/R损伤的最大益处的创新方法。我们将通过追求以下具体目标来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)免受损伤时所使用的信号机制和受体。我们将使用高纯度的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表达是否影响损伤后ISC的扩增和分化。我们将使用一种新的体外隐窝绒毛器官培养系统和在体肠道I/R损伤模型来研究HB-EGF对ISC扩增和分化的影响。目的3)探讨骨髓来源的干细胞是否能增强HB-EGF介导的肠道保护作用。我们将在活体实验中确定干细胞动员或联合应用HB-EGF对肠道I/R损伤的保护作用。我们的研究结果预计将对改善肠I/R损伤患者的治疗干预产生重要的积极影响，此外还将从根本上促进对生长因子/SC在肠道中相互作用的了解。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。这项拟议的研究具有创新性，因为我们试图将目前针对肠I/R损伤的实验治疗从针对单一炎症介质转向旨在通过联合应用肠道细胞保护性生长因子和多能SC来保护和再生肠粘膜的策略。

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.