Role of Paneth Cells in Development of Necrotizing Enterocolitis

描述(申请人提供)：新生儿坏死性小肠结肠炎(NEC)是导致早产儿死亡和发病的唯一最具破坏性的胃肠道原因。虽然NEC的病理生理机制尚不确定，但主要的假说是肠道细菌穿透未成熟的肠上皮屏障防御，导致组织侵袭和随后的坏死。先天免疫系统的一个关键胃肠道细胞是位于肠道隐窝底部的潘氏细胞。潘氏细胞通过分泌促炎介质和抗菌物质来保护肠道。与年龄匹配的对照组相比，患有NEC的婴儿的Paneth细胞数量显著减少。尽管潘氏细胞在免疫功能中扮演着关键角色，但目前还不清楚这些细胞扮演着什么角色 在NEC的发病机制中起重要作用。传统的动物模型还没有发育出潘氏细胞，因此无法解决这一知识差距。这项临床前应用的总体目标是确定潘氏细胞在未成熟肠道组织损伤发展中的作用。为了实现这一目标，我们将利用我们最新描述的NEC小鼠模型，利用Paneth细胞坏死来诱导NEC样损伤。我们的假设是，Paneth细胞的丢失使未成熟的小肠容易发生NEC。在这一应用中，我们建议从以下两个方面验证这一假说：1：建立Paneth细胞参与NEC发病的机制。患有NEC的婴儿缺乏Paneth细胞，在Klebsiella存在的情况下，Paneth细胞在小鼠中产生NEC样病理。然而，Paneth细胞在肠道损伤中的作用尚不清楚。在这个目标中，我们将研究Paneth细胞丢失的方法，以及Paneth细胞分泌的作用，以确定Paneth细胞破坏如何使未成熟的回肠容易受到损伤。2：探讨TLR4信号在Paneth细胞消融诱导NEC中的作用。细菌是NEC发展所必需的，而TLR4的激活被认为是疾病发展的启动者。在NEC发生的回肠，TLR4在肠腺表达。然而，这些研究是在尚未发育潘氏细胞的肠道中进行的。因此，尚不清楚TLR4在Paneth细胞消融诱导的NEC中起什么作用。在这个目标中，我们将研究TLR4信号通路与Paneth细胞破坏和随后的损伤有关。这些拟议的研究是创新的，因为他们调查了Paneth细胞在NEC发展中迄今未被认识到的作用。本研究的结果将为更清楚地了解Paneth细胞消融诱导未成熟肠道NEC的机制。这是开发预测疾病发展的新方法和治疗NEC的新药理学策略所需的第一个重要步骤。

DESCRIPTION (provided by applicant): Neonatal necrotizing enterocolitis (NEC) is the single most devastating gastrointestinal cause of mortality and morbidity in premature infants. Although the pathophysiology of NEC is uncertain, the leading hypothesis is that intestinal bacteria penetrate the immature intestinal epithelial barrier defenses, leading to tissue invasion and subsequent necrosis. A key gastrointestinal cell of the innate immune system is the Paneth cell, which is located in the base of the intestinal crypts. Paneth cells protect the intestine through secretion of pro-inflammatory mediators and antimicrobial substances. Compared to age-matched controls, infants with NEC have significantly decreased numbers of Paneth cells. Despite the key role Paneth cells play in immune function, it is unclear what role these cells play in the pathogenesis of NEC. Traditional animal models have not yet developed Paneth cells, and are thus unable to address this gap in knowledge. The overall objective of this pre-clinical application is to determine the role of Paneth cells in the development of tissue injury in the immature intestine. To achieve this objective, we will utilize our newly described mouse model of NEC that uses Paneth cell necrosis to induce NEC-like injury. Our hypothesis is that Paneth cell loss renders the immature small intestine susceptible to development of NEC. In this application, we propose to test this hypothesis in the following two Aims: 1: Establish the mechanism of Paneth cell involvement in the pathogenesis of NEC. Infants with NEC lack Paneth cells, and Paneth cell ablation in the presence of Klebsiella produces NEC- like pathology in mice. However, the role of Paneth cells in intestinal injury remains unclear. In this Aim we will examine methods of Paneth cell loss, and the role of Paneth cell secretions to establish how Paneth cell disruption renders the immature ileum susceptible to injury. 2: Establish the role of TLR4 signaling in Paneth cell ablation-induced NEC. Bacteria are required for development of NEC, and TLR4 activation has been proposed as an initiator for disease development4. In the ileum where NEC occurs, TLR4 is expressed in the intestinal crypts. However, these studies were done in intestines that had not yet developed Paneth cells. Thus, it is unclear what role TLR4 plays in Paneth cell ablation-induced NEC. In this Aim we will examine the TLR4 signaling pathway in connection to Paneth cell disruption and subsequent injury. These proposed studies are innovative as they investigate a heretofore-unappreciated role for Paneth cells in the development of NEC. The results of this research will provide a clearer understanding of the mechanism of Paneth cell ablation-induced NEC in the immature intestine. This is the first important step needed for developing novel ways to predict disease development and new pharmacologic strategies to treat NEC.