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Unraveling the enzymatic pathway of gut bacterial mucus degradation to treat inflammation

揭示肠道细菌粘液降解的酶促途径以治疗炎症

基本信息

批准号：
10027431
负责人：
Nicole M Koropatkin
金额：
$ 56.8万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-01 至 2024-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10027431
关键词：
Animals Anti-Inflammatory Agents Antigens Bacteria Bacterial Physiology Bacteroides Bacteroides thetaiotaomicron Biological Assay Biology Calorimetry Carbohydrates Cell surface Childhood Chronic Disease Citrobacter rodentium Colitis Colon Colorectal Cancer Communities Complex Complex Mixtures Crystallography Data Development Diet Dietary Fiber Discipline Disease Ecosystem Enzymatic Biochemistry Enzymes Epithelial Epithelium Event Family Fiber Future Gene Expression Profiling Genetic Polymorphism Glycobiology Glycoproteins Glycoside Hydrolases Glycosides Gnotobiotic Goals Goblet Cells Growth Health Human In Vitro Individual Infection Inflammation Inflammatory Bowel Diseases Interleukin-10 Intestines Knowledge Lead Link Measures Microbial Physiology Modeling Molecular Molecular Biology Molecular Weight Monosaccharides Mucins Mucous Membrane Mucous body substance Mus Mutation Nutrient Oligonucleotides Pathway interactions Peptide Hydrolases Play Polysaccharides Predisposition Process Proteins Recombinants Research Research Personnel Resort Role Series Signal Transduction Source Specificity Structure Substrate Specificity Sulfatases Sulfate Surface System Testing Therapeutic Thick Tissues Titrations Vertebral column Wild Type Mouse Work base combinatorial commensal microbes cytokine design enzyme activity experience experimental study fitness gastrointestinal genetic manipulation glycosylation gut bacteria gut microbes gut microbiota host-microbe interactions human disease improved in vivo in vivo Model inhibitor/antagonist interest loss of function member microbial microbial community microbiota mutant novel pathogen prevent structural biology synergism tool transcriptome sequencing whole genome

项目摘要

Summary The composition and physiology of the microbial community (microbiota) in the human colon has been linked to a number of diseases. Mechanistic details for most of these interactions are still badly needed. The shared focus of the four investigators assembled to conduct the proposed project is to understand how gut microbes interact with and metabolize complex carbohydrates—especially the glycans attached to secreted host mucus. Mucus is the first barrier that separates intestinal bacteria from host tissue and is a complex mixture of secreted mucin glycoprotein and other molecules. Some bacteria have evolved to forage on mucus as a source of nutrients. We have previously shown that this mucus foraging activity increases when exogenous dietary fiber polysaccharides are absent. Using a gnotobiotic model of fully sequenced human gut bacteria, we have shown that during fiber deficiency the gut microbiota resorts to degrading mucus for nutrients, leading to erosion of its integrity. In wild-type mice, a reduced mucus barrier increases epithelial access and lethal colitis by the mucosal pathogen, Citrobacter rodentium. More strikingly, when this same synthetic microbiota is assembled in mice deficient in interleukin 10, a cytokine for which loss of function is associated with human pediatric inflammatory bowel disease (IBD), animals develop lethal inflammation in the absence of pathogen, but only on a low fiber diet. Our work has therefore revealed functional connections between mucus integrity, diet and gut microbes in precipitating IBD. The complete deconstruction of mucin glycoproteins requires a consortium of enzymes: peptidases to hydrolyze the protein backbone and sulfatases and glycoside hydrolases that recognize sulfated or unsulfated oligo- and monosaccharides within discrete glycosidic linkage contexts. Our central hypothesis is that mucin is degraded in a series of sequential steps by individual activities in this enzyme consortium and that essential catalytic steps exist, which may be contributed by different species that work synergistically to degrade mucus. We will test this hypothesis by first defining the sequential action, positional specificity and key structural facets of bacterial enzymes required for degradation of gastrointestinal mucins. We will use sequential and combinatorial treatments of various forms of mucin with pure recombinant enzymes, which we have already identified in the members of our synthetic microbiota. In parallel, we will measure the requirement for individual, discrete mucus-degrading steps within genetically- manipulable model species using in vitro and mouse in vivo models as readouts. The research team is composed of four leaders in the disciplines of gut bacterial physiology and molecular biology, structural biology and enzymology, mucin biology and glycoanalytics, all with a shared interest in the mechanisms of mucus degradation and the consequences for human disease. Successful completion of these experiments will define a precise series of mechanistic steps for bacterial mucin degradation and could lead to therapies to limit these events in diseases like IBD.

总结