Bacterial regulation of intestinal antimicrobial defense

肠道抗菌防御的细菌调节

基本信息

批准号：
7889219
负责人：
LORA V HOOPER
金额：
$ 39.63万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-06-01 至 2014-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7889219
关键词：
Anti-Bacterial Agents Bacteria Binding Biochemical Biological Process C-Type Lectins Carbohydrates Communities Complex Development Enterobacteriaceae Epithelial Epithelial Cells Family Family member Gastrointestinal tract structure Genetic Transcription Goals Gram-Positive Bacteria Grant Homeostasis Human Immune In Vitro Inflammatory Bowel Diseases Intestines Knockout Mice Lead Lectin Ligands Lipid Binding Mediating Membrane Molecular Mus Orthologous Gene Pattern Penetration Peptidoglycan Probiotics Proteins Regulation Role Signal Transduction Surface Testing Therapeutic Tissues Toll-like receptors Work antimicrobial bactericide carbohydrate binding protein commensal microbes design gastrointestinal epithelium in vivo insight intestinal epithelium killings member microbial microbial host novel novel strategies pathogenic bacteria protein function public health relevance

项目摘要

DESCRIPTION (provided by applicant): A major challenge for mammalian hosts is to maintain symbiotic relationships with the vast bacterial communities that colonize the intestines. The intestinal epithelium is the primary barrier between the intestinal microbiota and internal host tissues, yet little is known about how epithelial cells control bacterial interactions with the mucosal surface and limit microbial penetration of the intestinal barrier. We have discovered a novel antibacterial factor, RegIIIg, which is produced by small intestinal epithelial cells. RegIIIg is a member of the C-type lectin family of carbohydrate-binding proteins that is discharged into the gut lumen. RegIIIg has direct bactericidal activity against Gram-positive bacteria and binds its bacterial targets via interactions with peptidoglycan carbohydrate. RegIIIg thus represents a previously unappreciated mechanism of mucosal defense and a new biological function for C-type lectins. Intestinal bacteria regulate RegIIIg transcription through direct activation of epithelial cell Toll-like receptors, revealing a direct dialog between enteric bacteria and the intestinal epithelium that regulates antimicrobial activity. As several other Reg family C-type lectins are produced by gut epithelia, directly bactericidal C-type lectins likely represent an important general mechanism of gut epithelial defense. The overall goal of this proposal is to extend our understanding of lectin- mediated antimicrobial defense of the intestinal mucosal surface. This work will involve three Specific Aims. First, we will use in vitro biochemical approaches to determine the molecular mechanism of lectin-mediated bactericidal activity. Second, we will use RegIIIg knockout mice to delineate how RegIIIg contributes to intestinal host-microbial homeostasis in vivo. Third, we will analyze other Reg proteins in vitro and in vivo in order to explore whether directly bactericidal lectins constitute a general mechanism of mucosal defense. Together, these studies should lead to fundamental insights into immune control of bacterial-mucosal associations, and will provide new perspectives on symbiotic host-microbial associations. PUBLIC HEALTH RELEVANCE: A major challenge for humans is to maintain symbiotic relationships with the vast bacterial communities that colonize the intestines. Intestinal epithelial cells produce abundant quantitites of RegIIIg, a carbohydrate binding protein that has a remarkable capacity to kill bacteria. In this grant we propose to explore the mechanism that RegIIIg uses to kill bacteria, and to understand how this protein functions to protect deeper host tissues from invasion by the intestine's normal microbial inhabitants. The results from these studies should yield new strategies for designing novel antimicrobial therapeutics, and could lead to new approaches to treating inflammatory bowel disease.

描述（由申请人提供）：哺乳动物宿主的一个主要挑战是与殖民肠道的庞大细菌群落保持共生关系。肠上皮是肠道微生物群和内部宿主组织之间的主要障碍，但对上皮细胞如何控制细菌相互作用与粘膜表面并限制肠壁的微生物渗透。我们发现了一种新型的抗菌因子Regiiig，该因子是由小肠上皮细胞产生的。 Regiiig是碳水化合物结合蛋白的C型凝集素家族的成员，该蛋白已排放到肠道内。 Regiiig具有直接的杀菌活性对革兰氏阳性细菌，并通过与肽聚糖碳水化合物的相互作用结合其细菌靶标。因此，Regiiig代表了先前未批准的粘膜防御机制和C型凝集素的新生物学功能。肠道细菌通过直接激活上皮细胞收费受体来调节雷吉伊格转录，揭示肠细菌与肠上皮之间的直接对话，从而调节抗菌活性。由于肠道上皮产生了其他几种Reg家族C型凝集素，因此直接的杀菌C型凝集素可能代表了肠上皮防御的重要一般机制。该提案的总体目标是扩展我们对肠粘膜表面的分线介导的抗菌防御的理解。这项工作将涉及三个具体目标。首先，我们将使用体外生化方法来确定凝集素介导的杀菌活性的分子机制。其次，我们将使用Regiiig敲除小鼠来描述Regiiig如何为体内肠道宿主微生物稳态做出贡献。第三，我们将在体外和体内分析其他Reg蛋白，以探索直接杀菌凝集素是否构成粘膜防御的一般机制。总之，这些研究应导致对细菌粘膜关联的免疫控制的基本见解，并将提供有关共生宿主菌群相关的新观点。公共卫生相关性：人类的主要挑战是与殖民肠道的广阔细菌群落保持共生关系。肠上皮细胞产生大量的雷吉伊格（Regiiig）的定量，这是一种碳水化合物结合蛋白，具有显着杀死细菌的能力。在这笔赠款中，我们建议探索雷吉伊格用来杀死细菌的机制，并了解该蛋白质如何保护更深的宿主组织免受肠道正常微生物居民的侵袭。这些研究的结果应产生设计新型抗菌疗法的新策略，并可能导致治疗炎症性肠病的新方法。