Prevention of Necrotizing Enterocolitis

项目概要/摘要 坏死性小肠结肠炎（NEC）是新生儿时期最具破坏性的胃肠道病理。 尽管发病机制尚不清楚，但有证据表明早产和配方奶喂养在其中发挥着重要作用 NEC。我们的长期目标是确定促进婴儿产后成熟和屏障功能的策略 有 NEC 风险。我们令人信服的数据表明，母乳 (HM) 中的透明质酸 (HA) 是一种很有前途的生物活性物质 加速小肠成熟并防止 NEC 发展的因子。 HA是独一无二的 在哺乳的第一周，非硫酸化糖胺聚糖以高浓度存在于初乳和母乳中。 我们之前表明，口服 35kDa HA (HA35)（HM HA 的模拟物）可增加肠道 上皮增殖、分化为潘氏细胞和杯状细胞以及紧密连接蛋白的表达。我们 还表明口服 HA35 可以减轻肠道损伤、细菌移位的严重程度，并减少 NEC 样肠损伤模型中的死亡率。使用 RNA-Seq、免疫组织化学和蛋白质印迹 通过分析，我们确定了雷帕霉素 (mTOR) 复合物 1 (mTORC1) 介导途径的机制靶点 HA35 处理后在回肠组织中上调。 mTOR 是一种丝氨酸/苏氨酸蛋白激酶，并且是 PI3K 相关激酶家族的成员，它与 mTORC1 和 mTORC2 形成复合体。研究表明 mTORC1 正常情况下调节潘氏细胞和杯状细胞，促进肠道干细胞活性和 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 尽管 mTORC1 在上皮稳态和再生中的作用，但其在 NEC 中的作用很大程度上尚不清楚。我们假设 HA35 的作用至少部分是通过 mTORC1 信号通路的激活来介导的。 由于 mTORC1 的激活促进肠道的增殖、分化和再生，我们还 假设调节 mTORC1 通路是预防/治疗的潜在治疗方法 NEC。在该项目结束时，我们将：(i) 确定 HA35 和 mTORC1 信号传导在体内平衡中的作用 在 NEC 样损伤模型中 (ii) 了解 mTOR 通路在 NEC 发病机制中的参与； (iii) 奠定 HA35 作为促进婴儿上皮保护的新型膳食补充剂的基础 有 NEC 风险。为了实现这些目标，我们组建了一支由科学家和临床医生组成的综合团队 mTORC1 信号通路、NEC 小鼠模型和人类早产儿的互补专业知识 肠道发育和损伤的肠样模型。我们提案的结果有可能极大地 增强我们对 NEC 发病机制的理解，并可能为有效的预防提供新的见解 疗法。

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.