The role of Hedgehog Signaling in gastric tissue repair and regeneration

项目摘要/摘要 虽然已经确定老年人胃溃疡的发生率主要是由于增加了对 NSAIDs和其他药物，以及幽门螺杆菌感染的增加，组织修复胃损伤的能力是 受伤了。我们认为溃疡在老年人胃中正常愈合的印象是错误的。可用的治疗方法 消化性溃疡本质上是基于用抗分泌药物抑制胃酸和根除 幽门螺杆菌感染。尽管有证据表明溃疡及其并发症是一种重点关注的负担 在老年人中，缺乏关于即使在H. 老年胃内幽门螺杆菌根除。这项建议的目标是：1)建立一种理解 对于胃再生的过程，然后2)确定基本衰老过程的机制 胃的损伤导致上皮不能修复以应对损伤。获得这种知识-- EDGE是实现我们了解过程的长期目标所需的连续研究的第一步- ESS对胃上皮损伤修复的反应。中心假设是Hedgehog信号的丢失 在正常的干细胞环境中，老年人的胃会导致胃的再生受损 对伤害的反应。这一假说是在初步数据的基础上提出的，这些数据表明，在 对胃溃疡有反应的有痉挛多肽/TFF2- 溃疡边缘基底部有化生(SPEM)细胞表达。我们的数据表明，SPEM代表了 严重胃溃疡损伤后负责伤口愈合的主要修复血统。我们还确认了- 证实了细胞表面蛋白CD44，特别是其变体亚型(CD44v)，标志着一群细胞 在表达Hedgehog受体Patted(PTCH)的修复性SPEM腺体内。此外，刺猬蛋白 Sonic Hedgehog(Shh)和India Hedgehog(IHH)是在修复过程中发挥修复作用的关键调节因素 分别通过调节巨噬细胞的浸润和CD44v的表达来应答损伤。以Strong为指导 根据初步数据，通过追求两个具体目标来检验这一假说：1)通过什么机制 Hedgehog信号调节胃上皮修复？以及，2)衰老的机制是什么 胃的过程会导致修复中断吗？这一假说将用骨髓嵌合体进行检验， 异时和等时并存的小鼠损伤/移植模型，使用小鼠和人- 衍生胃类器官和谱系图谱实验。在完成这些研究后，我们预计 定义对胃上皮修复至关重要的分子事件。支持的结果- 提出的研究有望极大地提高我们目前对这种机制的认识 衰老会导致上皮细胞修复中断。所提出的研究的基本原理是开发 测试治疗靶点疗效和其他策略的潜力，如干细胞治疗，用于再生- 老年性胃溃疡。

PROJECT SUMMARY/ABSTRACT While it is established that the incidence of gastric ulcers in the elderly is primarily due to increased use of NSAIDs and other medications, and increased H. pylori infection, the tissue's ability to repair gastric injuries is impaired. Our impression that ulcers heal normally in the aged stomach is false. The available treatments for peptic ulcer are essentially based on gastric acid suppression with anti-secretory drugs and the eradication of H. pylori infection. Despite the evidence that shows ulcers and their complications are a burden that is focused in the elderly, there is a lack of knowledge as to the molecular mechanisms that disrupt repair even after H. pylori eradication within the aged stomach. The objectives of this proposal are to 1) develop an understanding for the process of gastric regeneration, and to then 2) identify the mechanism by which the basic aging process of the stomach leads to an epithelium incapable of repair in response to injury. The acquisition of such knowl- edge is the first step in a continuum of research required to achieve our long-term goal to understand the proc- ess of gastric epithelial repair in response to injury. The central hypothesis is that loss of Hedgehog signaling within the normal stem cell environment of the aged stomach results in impaired regeneration of the stomach in response to injury. The hypothesis has been formulated on the basis of preliminary data that show during re- pair of the stomach in response to ulceration there is the emergence of Spasmolytic Polypeptide/TFF2- Expressing Metaplasia (SPEM) cells at the base of ulcer margin. Our data suggest that SPEM represents the major reparative lineage responsible for wound healing after severe gastric ulcer injury. We have also identi- fied that the cell surface protein CD44, in particular its variant isoforms (CD44v), marks a population of cells within reparative SPEM glands that express Hedgehog receptor Patched (Ptch). Moreover, Hedgehog proteins Sonic Hedgehog (Shh) and Indian Hedgehog (Ihh) are key regulatory factors that play reparative roles in re- sponse to injury by regulating macrophage infiltration and CD44v expression, respectively. Guided by strong preliminary data, this hypothesis is tested by pursuing two specific aims: 1) what is the mechanism by which Hedgehog signaling regulates gastric epithelial repair? And, 2) what is the mechanism by which the aging process of the stomach leads to disrupted repair? The hypothesis will be tested using bone marrow chimeras, heterochronic and isochronic parabioses, a mouse injury/transplantation model using mouse- and human- derived gastric organoids and lineage mapping experiments. At the completion of these studies, we expect to define the molecular events that are crucial for the repair of the gastric epithelium. Outcomes from the pro- posed studies are expected to have significantly advanced our current knowledge of the mechanism by which aging leads to disrupted epithelial repair. The rationale that underlies the research proposed is to develop the potential for testing therapeutic target efficacy and other strategies, such as stem-cell therapy, for the regen- eration of the aged stomach.