Prevention of Necrotizing Enterocolitis

项目总结/摘要 坏死性小肠结肠炎（NEC）是新生儿期最具破坏性的胃肠道病变。 虽然发病机制尚不清楚，但有证据表明早产和配方奶粉喂养在 NEC。我们的长期目标是确定促进婴儿出生后成熟和屏障功能的策略 NEC的风险。我们令人信服的数据表明，人乳（HM）中的透明质酸（HA）是一种有前途的生物活性物质， 促进小肠成熟和防止NEC发展的因子。HA是一个独特的 在泌乳的第一周，非硫酸化糖胺聚糖以高浓度存在于初乳和人乳中。 我们先前表明，口服35 kDa HA（HA 35），一种HM HA的模拟物，可以增加肠道免疫反应。 上皮细胞增殖、向潘氏细胞和杯状细胞的分化以及紧密连接蛋白的表达。我们 还表明，口服HA 35降低了肠道损伤的严重程度，细菌移位， NEC样肠损伤模型中的死亡率。使用RNA-Seq、免疫组织化学和western blot 分析，我们确定了雷帕霉素（mTOR）复合物1（mTORC 1）介导的途径的机制靶点 HA 35处理后回肠组织中的表达上调。mTOR是一种丝氨酸/苏氨酸蛋白激酶， PI 3 K相关激酶家族，其复合mTORC 1和mTORC 2。研究表明mTORC 1 在正常条件下调节潘氏细胞和杯状细胞，并促进肠干细胞活性， 放射损伤后上皮修复和成人结肠炎模型。尽管有新的证据支持其关键的 尽管mTORC 1在上皮稳态和再生中的作用，但其在NEC中的作用在很大程度上是未知的。我们假设 HA 35的作用至少部分是通过激活mTORC 1信号通路介导的。 由于mTORC 1的激活促进了肠道的增殖、分化和再生，我们还 假设调节mTORC 1通路是预防/治疗mTORC 1的潜在治疗方法， NEC。在这个项目的最后，我们将：（i）确定HA 35和mTORC 1信号转导在稳态中的作用 和在NEC样损伤模型中（ii）了解mTOR通路在NEC发病机制中的参与; 和（iii）建立HA 35作为促进婴儿上皮保护的新型膳食补充剂的基础 NEC的风险。为了实现这些目标，我们组建了一个由科学家和临床医生组成的整合良好的团队， 在mTORC 1信号通路、NEC的小鼠模型和人类早产儿 肠发育和损伤的肠模型。我们提案的结果有可能大大 增强我们对NEC发病机制的理解，并可能为有效预防NEC提供新的见解。 治疗

Project Summary/Abstract Necrotizing enterocolitis (NEC) is the most devastating gastrointestinal pathology in the newborn period. Although the pathogenesis is unclear, evidence suggests prematurity and formula feeding play major roles in NEC. Our long-term goal is to identify strategies that promote postnatal maturation and barrier function in infants at risk of NEC. Our compelling data show that hyaluronan (HA) in human milk (HM) is a promising bioactive factor that accelerate small intestinal maturation and protect against the development of NEC. HA is a unique nonsulfated glycosaminoglycan present in high concentrations in colostrum and HM in the first weeks of lactation. We previously showed that oral administration of 35kDa HA ( HA35), a mimic of HM HA, increases intestinal epithelial proliferation, differentiation into Paneth and goblet cells, and expression of tight junction proteins. We also showed that oral HA35 reduces the severity of the intestinal injury, bacterial translocation, and decreases mortality in a NEC-like intestinal injury model. Using RNA-Seq, immunohistochemistry, and western blot analyses, we identified the mechanistic target of rapamycin (mTOR) complex 1 (mTORC1)-mediated pathway was upregulated in ileal tissues by HA35 treatment. mTOR is a serine/threonine-protein kinase and a member of the PI3K-related kinase family, which complexes mTORC1 and mTORC2. Studies suggest mTORC1 regulates Paneth and goblet cells under normal conditions, and promotes intestinal stem cell activity and epithelial repair post-radiation injury and adult colitis model. Despite emerging evidence supporting its critical role in epithelial homeostasis and regeneration, the role of mTORC1 in NEC is largely unknown. We hypothesize that the effects of HA35 are mediated, at least in part, through activation of the mTORC1 signaling pathway. Since activation of mTORC1 promotes proliferation, differentiation, and regeneration of the gut, we also hypothesize that modulating the mTORC1 pathway is a potential therapeutic approach in preventing/treating NEC. At the end of this project, we will : (i) determine the role of HA35 and mTORC1 signaling in homeostasis and in NEC-like injury models (ii) understand the involvement of the mTOR pathway in the pathogenesis of NEC; and (iii) establish the basis of HA35 as a novel dietary supplement that promotes epithelial protection in infants at risk of NEC. To achieve these goals, we assembled a well-integrated team of scientists and clinicians with complementary expertise in mTORC1 signaling pathway, murine modeling of NEC, and human premature enteroid models of intestinal development and injury. The results of our proposal have the potential to greatly enhance our understanding of NEC pathogenesis, and potentially provide novel insight into effective preventative therapies.