Pathobiology of Diabetic Gastroenteropathy

糖尿病胃肠病的病理学

• 批准号: 7109154
• 负责人: GIANRICO FARRUGIA
• 金额: $ 32.89万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7109154
• 关键词: biological signal transduction; carbon monoxide; cell death; cytoprotection; diabetes mellitus; diabetic neuropathy; electrophysiology; enteric nervous system; enzyme activity; enzyme induction /repression; enzyme mechanism; free radical oxygen; gastrointestinal motility /pressure; heme oxygenase; human tissue; immunocytochemistry; intestine disorder; laboratory mouse; molecular biology; nitric oxide; nitric oxide synthase; oxidative stress; pathologic process; stomach disorder; tissue /cell culture

Normal gastrointestinal motility requires maintenance of enteric nerves and the networks of interstitial cells of Cajal (ICC). The overall objective of this proposal is to identify the mechanisms that underlie the pathobiology of diabetic gastroenteropathy (DGE). Our preliminary data suggest a central role for the neuronal nitric oxide synthase/nitric oxide (nNOS/NO) and the heme oxygenase/carbon monoxide (HO/CO) pathways in the maintenance of ICC networks in diabetes. We have made the following key preliminary observations: HO1 is up-regulated in diabetes and serves as a protective mechanism against diabetes-induced oxidative stress. NO up-regulates HO1. Loss of nNOS is an early step in the development of DGE resulting in decrease in NO, loss of up-regulation of HO1 and subsequent decrease in ICC numbers. Supporting the hypothesis that NO is cytoprotective to ICC are preliminary data that show that ICC numbers are decreased in nNOS knockout mice, NOS inhibitors decrease ICC numbers, and NO donors increase ICC numbers in culture. Also, nNOS expression is decreased, HO1 up-regulation is lost and ICC numbers are decreased in patients with DGE. We have also developed animal and human tissue models for DGE and developed a non-invasive test to determine gastric emptying in mice. Based on this work we have generated the novel hypothesis that up-regulation of the HO1/CO pathway by reactive oxygen species serves as an initial cytoprotective mechanism against damage to ICC by AGE and reactive oxygen species. Loss of nNOS expression from enteric nerves leads to loss of continued up-regulation of HO1 resulting in oxidative injury to ICC. Loss of ICC results in loss of the pacemaker signal, failure to amplify neuronal signals and dysmotility. The proposal has two specific aims. In the first aim we will test the hypothesis that DGE results from initial loss of nNOS expression and subsequent loss of ICC. In the second aim we will test the hypothesis that the HO/CO pathway is cytoprotective to ICC and that aberrant regulation of the HO/CO pathway results in decreased ICC and subsequent DGE. The studies will employ newly developed gastric emptying and ICC culture techniques, electrophysiology, immunohistochemistry, and molecular biology to answer the questions raised. We are now uniquely poised to provide new information on the mechanisms that underlie the development of DGE. As this work will identify basic mechanisms that underlie maintenance of ICC it also has implications for further understanding the pathophysioIogy of many of the motility disorders linked to disorders in ICC number and function.

正常的胃肠道运动需要维持肠神经和卡哈尔间质细胞 (ICC) 网络。该提案的总体目标是确定糖尿病胃肠病 (DGE) 病理学的机制。我们的初步数据表明，神经元一氧化氮合酶/一氧化氮 (nNOS/NO) 和血红素加氧酶/一氧化碳 (HO/CO) 通路在糖尿病 ICC 网络的维持中发挥着核心作用。我们进行了以下关键的初步观察： HO1 在糖尿病中表达上调，并作为针对糖尿病引起的氧化应激的保护机制。 NO 上调 HO1。 nNOS 的丧失是 DGE 发展的早期步骤，导致 NO 减少、HO1 上调丧失以及随后 ICC 数量减少。 支持 NO 对 ICC 具有细胞保护作用这一假设的初步数据表明，nNOS 敲除小鼠中 ICC 数量减少，NOS 抑制剂减少了 ICC 数量，NO 供体增加了培养物中的 ICC 数量。此外，DGE 患者中 nNOS 表达降低，HO1 上调消失，ICC 数量减少。我们还开发了 DGE 的动物和人体组织模型，并开发了一种非侵入性测试来确定小鼠的胃排空情况。基于这项工作，我们提出了一个新的假设：活性氧对 HO1/CO 途径的上调是针对 AGE 和活性氧对 ICC 损伤的初始细胞保护机制。 肠神经 nNOS 表达的丧失导致 HO1 持续上调的丧失 导致 ICC 氧化损伤。 ICC 丢失会导致起搏器信号丢失、无法 放大神经元信号和运动障碍。该提案有两个具体目标。在第一个目标中，我们将检验以下假设：DGE 是由最初 nNOS 表达缺失和随后 ICC 缺失引起的。在第二个目标中，我们将检验以下假设：HO/CO 途径对 ICC 具有细胞保护作用，并且 HO/CO 途径的异常调节会导致 ICC 和随后的 DGE 降低。这些研究将采用新开发的胃排空和ICC培养技术、电生理学、免疫组织化学和分子生物学来回答提出的问题。我们现在准备提供有关 DGE 发展基础机制的新信息。由于这项工作将确定 ICC 维持的基本机制，因此对于进一步了解与 ICC 数量和功能障碍相关的许多运动障碍的病理生理学也具有重要意义。