Mechanisms of acute bowel injury Role of NF-KB

描述(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，导致极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发育的分子机制。这将导致对这种毁灭性疾病的预防和治疗。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。这一奖项将允许在迈克尔·卡普兰博士和特伦斯·巴雷特博士的指导下，在出色的研究环境下，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-kB在肠道中受到发育调节，并在新生大鼠NEC模型中持续激活。我的总体假设是，NEC是由于早产儿肠道中核因子-kB对细菌产物的长期激活和局部产生的炎性脂质介质，如血小板激活因子(PAF)，导致中性粒细胞浸润和坏死。在早产儿中，这种持续的核因子-kB激活导致促炎细胞因子(如肿瘤坏死因子)、趋化因子(如MIP-2)和黏附分子(如ICAM-1)上调，从而放大炎症反应。结果，中性粒细胞被动员和激活，造成不可逆转的组织损伤和坏死。本研究的具体目的如下：1)研究低氧-冷应激配方喂养诱导的新生NEC模型中核因子-kB的活化；2)研究核因子-kB在新生NEC模型中的作用及其在急性肠损伤模型中的作用机制；3)检测肠道菌群的调节和益生菌治疗对新生NEC模型中肠道核因子-kB激活的影响。为此，提出了几种转基因小鼠模型：缺乏或过度表达特定的核因子-kB亚基的小鼠，表达依赖于核因子-kB的荧光素酶的报告鼠，最后将使用体内基因转移。了解核因子-kB激活途径的发育差异可能导致针对坏死性小肠结肠炎早期阶段抑制核因子-kB激活的特定策略。这可以防止其发展为不可逆转的肠道损伤，并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.