Mechanisms of acute bowel injury Role of NF-KB

描述（由申请人提供）：坏死性小肠结肠炎（NEC）是新生儿重症监护病房的一个主要问题，导致很高的发病率和死亡率。我的长期职业目标是阐明导致早产儿NEC发展的分子机制。这将有助于预防和治疗这一毁灭性疾病。我的短期目标是获得知识和新的技术技能（如体内基因转移和激光捕获显微解剖），使我能够在NEC研究领域做出重大贡献，并成为一名独立的研究科学家。该奖项将在Michael Caplan博士和Terrence Barrett博士的指导下，为实现这些目标提供必要的支持。我们有初步证据表明，转录因子核因子- (NF-kB)在肠中受到发育调节，并在新生大鼠NEC模型中持续激活。我的总体假设是，NEC是由于早肠中NF- kB对细菌产物和局部产生的炎性脂质介质（如血小板活化因子（PAF））的反应而长时间激活，导致中性粒细胞浸润和坏死。在早产儿中，这种持续的NF-kB激活导致促炎细胞因子（如TNF）、趋化因子（如MIP-2）和粘附分子（如ICAM-1）的上调，从而放大炎症反应。因此，中性粒细胞被动员和激活，引起不可逆的组织损伤和坏死。以下具体目标将被解决：1)表征缺氧-冷应激-配方喂养诱导的NEC新生儿模型中NF-kB的激活；2)研究NF-kB在新生儿NEC模型中的作用及其在急性肠损伤模型中的作用机制；3)研究肠道菌群调节和益生菌治疗对新生儿NEC模型肠道NF-KB激活的影响。为此，提出了几种转基因小鼠模型：缺乏或过表达NF-kB特定亚基的小鼠，表达NF-kB依赖性荧光素酶的报告小鼠，最后使用体内基因转移。了解NF-kB激活途径的发育差异可能会导致在坏死性小肠结肠炎早期抑制NF-kB激活的特定策略。这可以防止其向不可逆的肠道损伤发展，提高早产儿的存活率。

DESCRIPTION (provided by applicant): Necrotizing enterocolitis (NEC) is a major concern in the neonatal intensive care unit, causing great morbidity and mortality. My long-term career goal is to elucidate the molecular mechanisms that lead to the development of NEC in the premature newborn infant. This will lead to the prevention and treatment of this devastating disease. My short-term goals are to gain knowledge and novel technical skills (such as in vivo gene transfer and laser-capture microdissection) that will enable me to make significant contributions in the field of NEC research and to become an independent research scientist. This award would allow the necessary support to achieve these goals, under the mentorship of Dr. Michael Caplan and Dr. Terrence Barrett in an excellent research environment. We have preliminary evidence that the transcription factor nuclear factor- (NF-kB) is developmentally regulated in the intestine and is persistently activated in a neonatal rat model of NEC. My overall hypothesis is that NEC results from the prolonged activation of NF- kB in the premature intestine in response to bacterial products and locally produced inflammatory lipid mediators such as platelet-activating factor (PAF), causing neutrophil infiltration and necrosis. In the premature infant, this persistent NF-kB activation leads to the upregulation of pro-inflammatory cytokines (e.g. TNF), chemokines (e.g. MIP-2) and adhesion molecules (e.g. ICAM-1) which amplify the inflammatory response. As a result, neutrophils are mobilized and activated, causing irreversible tissue injury and necrosis. The following specific aims will be addressed: 1) to characterize NF-kB activation in the neonatal model of NEC induced by hypoxia-cold stress-formula feeding; 2) to study the role of NF-kB in the neonatal NEC model and its mechanisms of action in a model of acute bowel injury; 3) to examine the effect of modulating the intestinal flora and treatment with probiotics on intestinal NF-KB activation in the neonatal NEC model. To do so, several transgenic mice models are proposed: mice lacking or over-expressing a specific subunit of NF-kB, reporter mice expressing NF-kB-dependent luciferase and finally in vivo gene transfer will be used. Understanding the developmental differences in the NF-kB activating pathway might lead to specific strategies geared at inhibiting NF-kB activation in the early stages of necrotizingenterocolitis. This could prevent its progression toward irreversible intestinal damage and improve the survival of premature infants.