The role of Hedgehog Signaling in gastric tissue repair and regeneration

项目总结/摘要 虽然已经确定老年人胃溃疡的发病率主要是由于增加使用 NSAID和其他药物，并增加H。幽门螺杆菌感染时，组织修复胃损伤的能力是 受损我们认为老年胃溃疡会正常愈合的印象是错误的。现有的治疗方法 消化性溃疡基本上是基于胃酸抑制与抗分泌药物和根除 H.幽门感染尽管有证据表明溃疡及其并发症是一个负担， 在老年人中，对于即使在H. 幽门螺杆菌根除在老年人的胃。本提案的目标是：（1）建立一种理解 胃再生的过程，然后2）确定基本衰老过程的机制， 导致上皮细胞不能对损伤做出修复反应。获得这样的知识- 边缘是实现我们的长期目标所需的连续研究的第一步， 损伤后胃上皮修复的研究核心假设是刺猬信号的丢失 在老年胃的正常干细胞环境中， 对伤害的反应。这一假设是根据初步数据提出的，这些数据显示， 对胃溃疡的反应是出现痉挛性多肽/TFF 2- 在溃疡边缘的基部表达化生（SPEM）细胞。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谱系。我们还发现- 证实了细胞表面蛋白CD 44，特别是其变体同种型（CD 44 v），标志着细胞群 在表达Hedgehog受体Patched（Ptch）的修复性SPEM腺体内。此外，刺猬蛋白 Sonic Hedgehog（Shh）和Indian Hedgehog（Ihh）是修复神经元损伤的关键调节因子。 分别通过调节巨噬细胞浸润和CD 44 v表达来响应损伤。以强为导 初步数据，这一假设是通过追求两个特定的目标进行测试：1）是什么机制， Hedgehog信号调节胃上皮修复？2）衰老的机制是什么？ 胃的过程会导致修复中断？该假设将使用骨髓嵌合体进行检验， 异时性和等时性副甲状腺肿，使用小鼠和人的小鼠损伤/移植模型， 衍生的胃类器官和谱系作图实验。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。结果，亲- 提出的研究预计将大大提高我们目前的知识的机制， 老化导致上皮修复被破坏。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， 老年人的胃。

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.