Susan Tonkonogy

The Gnotobiotic Core at the College of Veterinary Medicine, North Carolina State University will support the mission of the Center for Gastrointestinal Biology and Disease (CGIBD) by providing germ-free and gnotobiotic rodents and associated technical services, including consultation and training to explore the hypothesis that commensal bacteria fundamentally influence normal intestinal and extra-intestinal physiologic processes in normal (genetically resistant) hosts as well as pathogenic physiologic inflammatory and neoplastic responses in genetically susceptible hosts. The goal of this Gnotobiotic Core is to serve as a resource for multidisciplinary CGIBD investigators to examine physiologic and pathophysiologic differences in germ-free (sterile) vs. gnotobiotic (known life) rodents of different genetic backgrounds. These investigators can precisely manipulate the intestinal microbiota by selectively colonizing rodents born in the germ-free environment with single or multiple commensal or pathogenic bacterial species. Many mechanistic questions regarding the pathogenesis of intestinal inflammation, the development of mucosal innate and acquired immune responses, and the regulation of epithelial, developmental, and homeostatic processes can only be answered by using rodents with carefully defined microbiota.

The Gnotobiotic Core of the Center for Gastrointestinal Biology and Disease (CGIBD) will provide investigators with the rodents and resources to explore the hypothesis that commensal bacteria fundamentally influence the normal physiologic processes in of multiple organs in normal (genetically resistant) hosts as well as pathogenic physiologic inflammatory and neoplastic responses in genetically susceptible hosts. The goal of this Gnotobiotic Core is to serve as a resource for multidisciplinary CGIBD investigators to examine physiologic and pathophysiologic differences in germ-free (sterile) vs. gnotobiotic (known life) and specific pathogen free (SPF) rodents of different genetic backgrounds. These investigators can precisely manipulate the intestinal microbiota by selectively colonizing rodents born in the germ-free environment with single or multiple commensal or pathogenic bacterial species. Many mechanistic questions regarding the pathogenesis of intestinal inflammation, the development of mucosal innate and acquired immune responses, and the regulation of epithelial, developmental, and homeostatic processes can only be answered by using rodents with carefully defined microbiota.

The Gnotobiotic Animal Core of the Center for Gastrointestinal Biology and Disease (CGIBD) will provide CGIBD and external investigators with the rodent resources to explore the hypothesis that commensal bacteria fundamentally influence the normal physiologic processes of multiple organs in normal (genetically resistant) hosts as well as pathogenic physiologic inflammatory and neoplastic responses in genetically susceptible hosts. The goal of this Gnotobiotic Animal Core is to serve as a resource for multidisciplinary CGIBD investigators to examine physiologic and pathophysiologic differences in germ-free (sterile) vs. gnotobiotic (known life) and specific pathogen-free (SPF) rodents of different genetic backgrounds. These investigators can precisely manipulate the bacterial flora by selectively colonizing rodents born in the germ-free environment with single or multiple commensal or pathogenic bacterial species. Many mechanistic questions regarding the pathogenesis of intestinal inflammation, the development of mucosal innate and acquired immune responses, and regulation of epithelial developmental and homeostatic processes can only be answered by using rodents with carefully defined microbial flora.

Crohn?s disease and ulcerative colitis, collectively referred to as inflammatory bowel diseases (IBD), are immunologically mediated disorders with genetic and environmental components. Genetic factors include defective immunoregulation, mucosal barrier integrity/repair and bacterial killing, while enteric bacteria provide very important environmental stimuli for inflammation in the distal ileum and colon. We have investigated the general hypothesis that chronic intestinal inflammation in genetically susceptible hosts is mediated by overly aggressive bacterial antigen-specific T cell responses to a subset of commensal enteric bacterial species. Rodent models of chronic, T cell-dependent intestinal inflammation have provided important insights into the pathogenesis of these idiopathic disorders. An emerging theme from multiple studies is that defective innate responses can activate pathogenic adaptive immune responses. Pathogenic activities of different bacteria are mediated by a wide variety of virulence genes that encode fimbria, pili, toxin production and iron acquisition proteins. Our overall hypothesis is that chronic intestinal inflammation can result from persistent exposure to mucosally associated and intracellular commensal enteric bacteria that induce aggressive anti-bacterial TH1 and TH17-mediated immune responses. Persistent bacterial exposure is caused by either 1) Colonization with commensal bacteria that express virulence factors that promote intestinal epithelial cell adherence, invasion and resistance to intracellular killing within epithelial cells and macrophages, or 2) Genetically determined host innate defects in bacterial killing and mucosal barrier function. We will investigate this clinically relevant hypothesis with the following Specific Aims: 1. Determine whether bacterial virulence genes that promote intracellular persistence and mucosal translocation of E. coli and E. faecalis influence experimental intestinal inflammation and mucosal immune responses. 2. Determine the functional consequences of genetic defects in innate bacterial killing by epithelial cells and macrophages exposed to invasive/persistent E. coli and E. faecalis strains vs. nonpathogenic strains.

Hypotheses: 1. Chronic intestinal inflammation in genetically susceptible hosts is caused by dysregulated cell-mediated immune responses to bacterial antigens unique to each host. 2. Nonresponsiveness in normal hosts is mediated by carefully regulated interactions between innate immune cells and T cells that inhibit pathogenic immune responses to commensal enteric bacteria. We will address these hypotheses with the following Specific Aims: 1. Identify dominant B. vulgatus and commensal enteric bacterial antigens that induce immune-mediated colitis in HLA B27TG rats 2. Determine bacterial antigen specificity in T cell-mediated colitis 3. Identify mechanisms by which commensal luminal bacteria induce tolerance in normal hosts and chronic immune activation in genetically susceptible HLA B27TG rats These innovative studies explore mechanisms of pathogenic and tolerogenic immune responses to commensal enteric bacteria that determine chronic intestinal inflammation or homeostasis. They take advantage of our unique investigative environment that includes access to a gnotobiotic rodent facility, the proven abilities of a multidisciplinary investigative team, and novel preliminary data generated in the previous funding period.

The Gnotobiotic Animal Core of the Center for Gastrointestinal Biology and Disease (CGIBD) will provide CGIBD and external investigators with the rodent resources to explore the hypothesis that commensal bacteria fundamentally influence the normal physiologic processes in of multiple organs in normal (genetically resistant) hosts as well as pathogenic physiologic inflammatory and neoplastic responses in genetically susceptible hosts. The goal of this Gnotobiotic Animal Core is to serve as a resource for multidisciplinary CGIBD investigators to examine physiologic and pathophysiologic differences in germ-free (sterile) vs. gnotobiotic (known life) and specific pathogen-free (SPF) rodents of different genetic backgrounds. These investigators can precisely manipulate the bacterial flora by selectively colonizing rodents born in the germ-free environment with single or multiple commensal or pathogenic bacterial species. Many mechanistic questions regarding the pathogenesis of intestinal inflammation, the development of mucosal innate and acquired immune responses, and regulation of epithelial developmental and homeostatic processes can only be answered by using rodents with carefully defined microbial flora.

This request is for funds to purchase an autoclave.

The Gnotobiotic Animal Core of the Center for Gastrointestinal Biology and Disease (CGIBD) will provide CGIBD and external investigators with the rodent resources to explore the hypothesis that commensal bacteria fundamentally influence the normal physiologic processes in of multiple organs in normal (genetically resistant) hosts as well as pathogenic physiologic inflammatory and neoplastic responses in genetically susceptible hosts. The goal of this Gnotobiotic Animal Core is to serve as a resource for multidisciplinary CGIBD investigators to examine physiologic and pathophysiologic differences in germ-free (sterile) vs. gnotobiotic (known life) and specific pathogen-free (SPF) rodents of different genetic backgrounds. These investigators can precisely manipulate the bacterial flora by selectively colonizing rodents born in the germ-free environment with single or multiple commensal or pathogenic bacterial species. Many mechanistic questions regarding the pathogenesis of intestinal inflammation, the development of mucosal innate and acquired immune responses, and regulation of epithelial developmental and homeostatic processes can only be answered by using rodents with carefully defined microbial flora.

Continuation to support core CGIBD

Core project program