Development of a Model of Necrotizing Enterocolitis

描述（由申请方提供）：坏死性小肠结肠炎（NEC）是一种毁灭性的胃肠道疾病，主要发生于早产儿，其最严重形式的特征是远端回肠和近端结肠的广泛出血性炎性坏死。NEC每年影响美国数千名新生儿，10-50%的受影响个体死亡。由于该国每年有更多的早产儿出生，这种疾病的影响可能会导致更高的发病率和死亡率。 这种疾病的病理生理机制仍然知之甚少;然而，早产，肠内喂养，肠道缺氧缺血和细菌定植被认为是主要的风险因素。目前，在这种疾病的亚临床阶段没有预测性诊断测试。更好地了解NEC的发展机制，并在分子水平上阐明组织中的早期病理变化，将有助于改善治疗，并可能导致这种疾病的预防。 目前，用于研究NEC的最佳动物模型是新生大鼠模型。在这个模型中，NEC是通过给新生大鼠喂食基于牛奶的配方奶粉，然后将它们暴露于缺氧和冷应激而产生的。新生大鼠NEC模型的主要优点是许多临床和病理变化与人类相似。此外，人类NEC的主要风险因素（肠不成熟、肠内配方喂养和缺氧/缺血）是大鼠模型中发生疾病的重要因素。该模型的主要缺点是缺乏基因敲除或遗传修饰的大鼠品系，用于研究疾病发展和病理学机制。目前，在大鼠模型中的机制评价需要用特异性抗体或特异性化学抑制剂抑制潜在的疾病贡献者。缺乏同源的，敲除或自发突变的大鼠品系，严重阻碍了对这种疾病的研究。因此，利用NEC的新生小鼠模型的能力将指数地增加研究疾病发病机制的能力。 我们建议开发和表征NEC的新生小鼠模型。我们将尝试使用我们实验室目前用于在新生大鼠中开发NEC的方案在新生小鼠幼仔中诱导NEC-用基于牛奶的配方进行肠内人工喂养，加上每天两次暴露于窒息和冷应激。我们将确定（I）最佳菌株和有利于疾病发展的条件，以及（2）使用组织学、生物化学和分子手段表征这些菌株中的疾病发展。

DESCRIPTION (provided by applicant): Necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease, predominantly of prematurely born infants, characterized in its severest form by extensive hemorrhagic inflammatory necrosis of the distal ileum and proximal colon. NEC affects thousands of newborns in the U.S.A. every year with death occurring in 10-50% of affected individuals. As more premature infants are born in this country each year, the effects of this disease are likely to contribute to greater morbidity and mortality. The pathophysiology of this disease remains poorly understood; however prematurity, enteral feeding, intestinal hypoxia-ischemia, and bacterial colonization are considered major risk factors. Currently, no predictive diagnostic tests are available at the subclinical phase of this disease. A better understanding of the mechanisms involved in the development of NEC and elucidation of early pathological changes in tissues at the molecular level will help to improve therapy and could lead to prevention of this disease. Currently, the best animal model used to study NEC is the neonatal rat model. In this model, NEC is developed by feeding newborn rats milk-based formula and then exposing them to hypoxia and cold stress. The major advantage of the neonatal rat NEC model is that many clinical and pathological changes are similar to those found in humans. In addition, the major risk factors for human NEC (intestinal immaturity, enteral formula feeding, and hypoxia/ischemia) are essential factors to develop disease in the rat model. The major disadvantage of this model is the lack of knockout or genetically modified rat strains with which to investigate mechanisms of disease development and pathology. Currently, mechanistic evaluations in the rat model require inhibition of potential disease contributors with specific antibodies or specific chemical inhibitors. The paucity of congenic, knockout or spontaneous mutant rat strains has severely hampered research into this disease. Thus, the ability to utilize a neonatal mouse model of NEC would exponentially increase the ability to investigate disease pathogenesis. We propose to develop and characterize a neonatal mouse model of NEC. We will attempt to induce NEC in newborn mouse pups using the protocol currently utilized in our laboratory to develop NEC in neonatal rats - enteral hand feeding with cow-milk based formula coupled with twice daily exposure to asphyxia and cold stress. We will determine (I) the best strain(s) and conditions conducive to disease development, and (2) characterize disease development in these strains using histologic, biochemical and molecular means.