Bacterial regulation of intestinal antimicrobial defense

描述（由申请人提供）：非致病性肠道植物群在人类健康和疾病中起着关键作用，但对肠道微生物如何与其哺乳动物宿主沟通以建立互利关系知之甚少。为了研究这些关系，我们使用了一个体内系统，其中无菌小鼠定植有多形拟杆菌，多形拟杆菌是小鼠和人类肠道植物群的主要成员。激光捕获显微切割和微阵列分析已经确定了B。在Paneth细胞（一种专门用于抗微生物防御的小肠上皮细胞系）中，多形核调节编码抗微生物蛋白的基因的转录。此外，通常与断奶过渡相关的潘氏细胞抗菌基因表达的变化可以由成年无菌小鼠的细菌定植引起，这表明肠道细菌在潘氏细胞抗菌剂库的发展中起着指导性作用。这些结果导致了一种假设，即肠道细菌通过调节潘氏细胞基因表达来塑造肠道抗菌防御和粘膜屏障功能。提出了三个具体目标来解决这一假设。目的1将表征细菌调控的潘氏细胞抗菌基因在出生后发育过程中的表达模式和对微生物因素的反应。目的2将研究宿主模式识别受体，包括Toll样受体和Nod蛋白，对细菌-潘氏细胞相互作用的贡献。目的3提出研究Reg蛋白家族成员的抗微生物功能，该蛋白在潘氏细胞中通过与细菌的相互作用强烈诱导。总之，这些研究将对肠道细菌如何塑造肠道上皮先天免疫产生新的见解，并将导致更好地了解体内细菌-上皮相互作用的分子机制。此外，这项工作将有助于设计新的策略，以加强微生物在增强粘膜屏障中的作用。

DESCRIPTION (provided by applicant): The nonpathogenic intestinal flora play critical roles in human health and disease, yet very little is known about how commensal microbes communicate with their mammalian hosts to establish mutually beneficial relationships. To study these relationships, we use an in vivo system in which germ-free mice are colonized with Bacteroides thetaiotaomicron, a predominant member of the intestinal flora in mice and humans. Laser capture microdissection and microarray analysis have established that B. thetaiotaomicron regulates the transcription of genes encoding antimicrobial proteins in Paneth cells, a small intestinal epithelial lineage specialized for antimicrobial defense. Moreover, changes in Paneth cell antimicrobial gene expression that are normally associated with the weaning transition can be elicited by bacterial colonization of adult germ-free mice, suggesting that commensal bacteria play an instructive role in the development of the Paneth cell antimicrobial arsenal. These results have led to the hypothesis that commensal gut bacteria shape intestinal antimicrobial defense and mucosal barrier function by modulating Paneth cell gene expression. Three specific aims are proposed to address this hypothesis. Aim 1 will characterize the expression patterns of bacterially-regulated Paneth cell antimicrobial genes during postnatal development and in response to microbial factors. Aim 2 will examine the contributions of host pattern recognition receptors, including Toll-like receptors and Nod proteins, to bacteria-Paneth cell interactions. Aim 3 proposes to investigate an antimicrobial function for a member of the Reg family of proteins which is strongly induced in Paneth cells by interactions with commensal bacteria. Together, these studies will yield novel insights into how commensal bacteria shape gut epithelial innate immunity, and will lead to a better understanding of the molecular mechanisms underlying bacteria-epithelial interactions in vivo. Furthermore, this work will aid in designing novel strategies for strengthening the role of the microflora in enhancing the mucosal barrier.