PATHOPHYSIOLOGY OF TLR5KO COLITIS
Andrew T Gewirtz
Emory University, 1599 Clifton Road, 4th Floor, Atlanta, Ga 30322
Grant 1R01DK083890-01A2 from National Institute Of Diabetes And Digestive And Kidney Diseases
Abstract: Inflammatory bowel diseases (IBD) are associated with berrant mucosal immune responses to the enteric microflora. Innate immunity drives the active flares of disease while adaptive immune responses are thought to maintain the chronically inflamed state. While IBD has generally been associated with elevated immune responses to gut bacteria, the recent findings that IBD patients have impaired levels of innate immunity suggest that, in fact, at least some incidence of IBD may in fact result from an underlying innate immune deficiency. Thus, mechanistically dissecting how alterations in innate immunity can eventuate in chronic inflammation should help understand the pathophysiology of IBD. The bacterial protein flagellin, the monomeric subunit of flagella, is a dominant innate immune activator of intestinal epithelial cells. Thus, experimental study of the flagellin receptor, toll-like receptor 5 (TLR5), may provide mechanistic insights into how alterations in innate immunity can result in IBD. In accordance, we have recently observed that TLR5-KO mice develop spontaneous colitis. Such colitis is associated with alterations in gut microflora and appears to be dependent upon both innate and adaptive immunity. Thus, we hypothesize that TLR5 plays an essential role in "managing" the commensal microflora and that loss of TLR5 renders mice unable to properly manage their commensal microflora, resulting in chronic activation of other innate immune signaling pathways and development of "colitogenic" T-cells. Thus we propose to 1) Determine how loss of TLR5 affects immune cells and examine their role in TLR5KO colitis and 2) Define how loss of TLR5 affects the enteric microbiota and the role such changes play in driving colitis. Engineered deletion toll-like receptor 5 (TLR5), in mice, results in pontaneous colitis. This project seeks to define the pathophysiologic mechanisms that underlie such colitis. We expect this information will prove insightful toward understanding the pathogenesis of Crohn´s disease and ulcerative colitis, collectively referred to as inflammatory bowel disease
Keywords: Affect; Automobile Driving; Bacteria; Bacterial Gene Proteins; Bacterial Proteins; Cells; Chronic; Colitis; Crohn`s disease; Crohn`s disorder; Development; Disease; Disorder; Drivings, Automobile; Dysfunction; Engineering; Engineerings; Enteral; Enteric; Enteritis, Granulomatous; Epithelial Cells; Flagella; Flagellin; Flare; Functional disorder; Gene Products, Bacterial; INFLM; Immune; Immune response; Immunity; Immunity, Innate; Immunity, Native; Immunity, Natural; Immunity, Non-Specific; Incidence; Inflammation; Inflammatory Bowel Diseases; Inflammatory Bowel Disorder; Inflammatory Intestinal Disease; Inflammatory Intestinal Disorder; Intestinal; Intestines; Mammals, Mice; Mice; Mucosal Immune Responses; Murine; Mus; Natural Immunity; Pathogenesis; Patients; Physiopathology; Play; Receptor Protein; Role; Signal Pathway; T-Cells; T-Lymphocyte; TIL3; TLR4; TLR4 gene; TLR5; TLR5 receptor; TOLL; Thymus-Dependent Lymphocytes; Toll-Like Receptor 5; Toll/Interleukin-1 Receptor-Like Protein 3; Ulcerated Colitis; Ulcerative Colitis; bowel; disease/disorder; driving; eleocolitis; experiment; experimental research; experimental study; granulomatous enterocolitis; gut microflora; hToll; host response; immunoresponse; insight; pathophysiology; public health relevance; receptor; regional enteritis; research study; social role; thymus derived lymphocyte; toll-5 receptor
Relevance: Narrative Engineered deletion toll-like receptor 5 (TLR5), in mice, results in spontaneous colitis. This project seeks to define the pathophysiologic mechanisms that underlie such colitis. We expect this information will prove insightful toward understanding the pathogenesis of Crohn´s disease and ulcerative colitis, collectively referred to as inflammatory bowel disease
Project start date: 2010-04-15
Project end date: 2014-12-31
Budget start date: 15-APR-2010
Budget end date: 31-DEC-2010
PFA/PA: PA-07-070
1R01DK083890-01A2 (2010): $387500
Sponsored Links Excellgen http://Excellgen.com
Grants awarded to Andrew T Gewirtz
FLAGELLIN-INDUCED GUT EPITHELIAL CHEMOKINE SECRETION
Andrew T Gewirtz
Emory University, 1599 Clifton Road, 4th Floor, Atlanta, Ga 30322
Grant 3R01DK061417-07S2 from National Institute Of Diabetes And Digestive And Kidney Diseases
Abstract: The intestinal epithelium mediates the absorption of life-sustaining nutrients while protecting against the large and diverse population of bacteria that colonize this surface. While, classically, the gut epithelium was thought to manage these tasks primarily by functioning as a passive, albeit highly selective, barrier, research over the last dozen years has demonstrated that, in fact, the gut epithelium plays a very active role in protecting the host from both the commensal and potentially pathogenic bacteria that can colonize this surface. Consequently, understanding the interactions between bacteria, epithelial cells, and immune cells is important to understanding bacterial pathogenesis in the gut, systemic infection by food-borne pathogens, and chronic inflammatory diseases of the intestine in which there is a seemingly inappropriate immune response directed at the commensal enteric microflora. Our in vitro modeling of bacterial epithelial-interactions performed under this proposal revealed that ligation of toll-like receptor 5 (TLR5) by bacterial flagellin, the primary structural component of flagella, is a dominant means of activating innate immune signaling in intestinal epithelial cells. Flagellin is released by a number of pathogens and commensal microbes but TLR5 expression is polarized to the basolateral surface of the epithelium thus minimizing activation of pro-inflammatory signaling by flagellin released from commensal bacteria. Conversely, flagellated pathogens that can breech the epithelium or alter vesicular trafficking in epithelial cells activates TLR5-signaling in model epithelium. Such TLR5 signaling utilizes the NF-?B, MAPK and JaK-STAT signal transduction pathways result in a transient burst of gene expression seemingly designed to directly repel bacteria, recruit/activate immune cells, and prevent apoptosis. Such induction of gene expression can be envisaged to protect the host from pathogens but may contribute to the inflammatory sequellae associated with many enteric infections. Furthermore, that some pathogens such as Salmonella typhimurium have a specific mechanism that mediates release of flagellin monomers upon sensing of epithelial cells suggest that some pathogens might "deliberately" trigger TLR5 activation to aid in their dissemination. The in vivo studies performed to date are consistent with both of these possibilities. However, such studies have been far too limited in scope to provide a reasonable sense of the importance of the flagellin-TLR5 interaction in vivo let alone elucidate the mechanisms by which flagellin-induced signaling might affect the outcomes of host-bacteria interactions in health and disease. Thus, to fill this gap of knowledge, we outline a series of experiments to determine the mechanisms by which innate immune responses to flagellin affect the outcomes of host-bacterial interactions in vivo. Salmonella remain amongst the most prolific and ubiquitous microbial causes of disease in both developed and developing countries. Human disease caused by Salmonella can be divided into 2 primary categories 1) gut-restricted self-limiting gastroenteritis and Typhoid fever. Our research indicates that the interaction of the Salmonella protein flagellin with a host protein toll-like receptor 5 plays a key role in both disease processes. Thus, we propose to understand the role of the interaction in mouse models of disease
Keywords: Absorption; Affect; Apoptosis; Apoptosis Pathway; Bacteria; Categories; Cell Communication and Signaling; Cell Death, Programmed; Cell Signaling; Cells; Chronic; Citrobacter; Closure by Ligation; Cytokines, Chemotactic; Developed Countries; Developed Nations; Developing Countries; Developing Nations; Disease; Disease Outbreaks; Disorder; Enteral; Enteric; Enteric Fever; Epithelial; Epithelial Cells; Epithelium; Epithelium, Intestinal; Extracellular Signal-Regulated Kinase Gene; Flagella; Flagellata; Flagellin; Gastroenteritis; Gene Expression; Gut Epithelium; Gut Inflammation; Health; Heterogeneity, Population; Homologous Chemotactic Cytokines; Host Defense Mechanism; Immune; Immune response; Industrialized Countries; Industrialized Nations; Infection; Inflammatory; Inflammatory Diseases of the Intestinal Tract; Inflammatory disease of the intestine; Inflammatory disorder of the intestine; Intercrines; Intestinal; Intestinal Inflammation; Intestines; Intracellular Communication and Signaling; Knowledge; Less-Developed Countries; Less-Developed Nations; Life; Ligation; MAP Kinase Gene; MAPK; Mammals, Mice; Mastigophora; Measures; Mediating; Mice; Mitogen-Activated Protein Kinase Gene; Modeling; Molecular; Murine; Mus; Nutrient; Outbreaks; Outcome; Pathogenesis; Phenotype; Play; Population Heterogeneity; Process; Process of absorption; Proteins; Receptor Protein; Recruitment Activity; Research; Resistance; Role; S. typhimurium; S.typhimurium; SIS cytokines; Salmonella; Salmonella typhimurium; Series; Signal Transduction; Signal Transduction Pathway; Signal Transduction Systems; Signaling; Structure of intestinal epithelium; Surface; Systemic infection; TIL3; TLR5; TLR5 receptor; Third-World Countries; Third-World Nations; Toll-Like Receptor 5; Toll/Interleukin-1 Receptor-Like Protein 3; Typhoid; Typhoid Fever; Typhoids; Typhus, Abdominal; Under-Developed Countries; Under-Developed Nations; absorption; biological signal transduction; bowel; chemoattractant cytokine; chemokine; commensal bacteria; commensal microbes; design; designing; disease/disorder; diverse populations; experiment; experimental research; experimental study; flagellate; food born pathogen; food borne pathogen; foodborn pathogen; foodborne pathogen; gastrointestinal epithelium; gene product; heterogeneous population; host response; human disease; immunoresponse; in vitro Model; in vivo; insight; intestinal epithelium; microbial; monomer; mouse model; pathogen; pathogenic bacteria; prevent; preventing; public health relevance; receptor; recruit; research study; resistant; response; social role; toll-5 receptor; trafficking
Project start date: 2010-01-20
Project end date: 2010-12-31
Budget start date: 20-JAN-2010
Budget end date: 31-DEC-2010
PFA/PA: PA-07-070
3R01DK061417-07S2 (2010): $101600
5R01DK061417-08 (2010): $326081
5R01DK061417-07 (2009): $329375
2R01DK061417-06A1 (2008): $329198
5R01DK061417-05 (2007): $230598
5R01DK061417-04 (2006): $237485
5R01DK061417-03 (2005): $243200
5R01DK061417-02 (2004): $243200
1R01DK061417-01A1 (2003): $243200
3R01DK061417-07S1 (2009): $524750
Sponsored Links Excellgen http://Excellgen.com
GUT EPITHELIAL INNATE IMMUNE RESPONSE TO ROTAVIRUS
Andrew T Gewirtz
Emory University, 1599 Clifton Road, 4th Floor, Atlanta, Ga 30322
Grant 5R21AI083420-02 from National Institute Of Allergy And Infectious Diseases
Abstract: Bacterial-induced changes in intestinal epithelial cell gene expression play a pivotal role in host defense and may also drive the seemingly inappropriate inflammation associated with Crohn´s disease. Accordingly, investigation of the mechanisms governing such bacterial-epithelial interactions has revealed some of the key host and bacterial determinants that mediate mucosal inflammation in the gut. Although much less studied, changes in epithelial cell gene expression can also be induced by viruses, which like bacteria often first colonize their hosts via the mucosal epithelium. Importantly, although not yet well defined, the specific genes upregulated upon epithelial colonization by viruses appear to be markedly distinct than that induced by bacteria. We hypothesize that, analogous to the case for bacteria, viral-induced intestinal epithelial gene expression, mediated by epithelial pattern recognition receptors, plays an important role in both innate and adaptive immune responses to ingested viral pathogens. Such host responses are likely an important component of host defense and may also be associated with viral pathogenesis. While we anticipate that developing this hypothesis will be a long term endeavor, the focused goal of this 2-year R21 proposal is to begin to explore this under-investigated area by examining mechanisms that mediate innate immune responses to rotavirus in intestinal epithelia. RELEVANCE The goal of this project is to understand the means by which the intestine clears viral infections and how such clearance results in protection against subsequent infection. The specific virus on which we will focus is rotavirus, which is one of the world´s most common causes of gastroenteritis. The knowledge yielded by this project should aid the design of strategies to treat and prevent mucosally acquired viral infections in humans
Keywords: Area; Bacteria; Bone Marrow; Crohn`s disease; Crohn`s disorder; Diarrhea; Double-Stranded RNA; Enteritis, Granulomatous; Epithelial; Epithelial Cells; Epithelium; Epithelium, Intestinal; Gastroenteritis; Gene Expression; Generations; Genes; Goals; Hematopoietic; Host Defense; Human; Human, General; INFLM; Immune; Immune response; Infection; Inflammation; Intestinal; Intestines; Investigation; Knowledge; Life; Mammals, Mice; Man (Taxonomy); Man, Modern; Measures; Mediating; Messenger RNA; Mice; Modeling; Mucosal Inflammation; Mucositis; Murine; Mus; Pattern recognition receptor; Play; Proteins; RNA, Double-Stranded; RNA, Messenger; Relative; Relative (related person); Reporting; Reticuloendothelial System, Bone Marrow; Role; Rotavirus; Signal Pathway; Structure of intestinal epithelium; TLR3; TLR3 gene; Viral; Viral Diseases; Viral Pathogenesis; Virus; Virus Diseases; Viruses, General; adaptive immunity; bowel; design; designing; dsRNA; eleocolitis; gene product; granulomatous enterocolitis; host response; immunoresponse; in vivo; intestinal epithelium; mRNA; pathogen; prevent; preventing; regional enteritis; social role; viral infection; virus infection
Relevance: Project Narritive The goal of this project is to understand the means by which the intestine clears viral infections and how such clearance results in protection against subsequent infection. The specific virus on which we will focus is rotavirus, which is one of the world´s most common causes of gastroenteritis. The knowledge yielded by this project should aid the design of strategies to treat and prevent mucosally acquired viral infections in humans
Project start date: 2009-06-15
Project end date: 2011-05-31
Budget start date: 1-JUN-2010
Budget end date: 31-MAY-2011
PFA/PA: RFA-AI-08-020
5R21AI083420-02 (2010): $193750
1R21AI083420-01 (2009): $232500
REGULATION OF INTESTINAL EPITHELIAL CHEMOKINE SECRETION
Andrew T Gewirtz, Associate Professor
Pathology And Lab Medicineemory University
1599 Clifton Road, 4th Floor
atlanta, Ga 30322
Grant 5K01DK002792-02 from National Institute Of Diabetes And Digestive And Kidney Diseases IRG: DDK
Abstract: adapted ) The Research This project will investigate the regulation of intestinal epithelial chemokine secretion as well as down-regulating this chemokine secretion via lipoxins- endogenously biosynthesized anti-inflammatory eicosanoids. Specifically, this project has three major aims. One, define the role of calcium signaling in regulating epithelial secretion of IL-8 (a potent neutrophil chemoattractant). Two, elucidate the interactions between the apical surface of the intestinal epithelium that activate the signals that mediate epithelial IL-8 secretion. Three, investigate the molecular mechanism by which lipoxin A4 down-regulates epithelial chemokine secretion and whether lipoxin A4 stable analogs can down-regulate intestinal inflammation in a mouse model of colitis. As epithelial chemokine secretion is thought to drive the neutrophil movement that defines active intestinal inflammation, this research will increase our understanding of the molecular basis of active inflammation. Since chronic inflammatory diseases of the intestine may result from aberrant mucosal immune responses to normal gut microflora, this project´s focus on bacterial-induced inflammation is particularly germane to the understanding of these debilitating disorders. Further, this work will further develop the very promising therapeutic strategy of treating intestinal inflammation via lipoxin stable analogs. The Candidate Dr. Gewirtz has a solid background in both signal transduction and bacterial-epithelial-neutrophil interactions. He has been very productive in these areas as evidenced by his publications including 4 first authored original research papers published (or in press) within the last year. Following this additional period of mentored research, Dr. Gewirtz will be well positioned for a fruitful career as an independent NIH-funded investigator. The Mentors The sponsor Dr. Madara and co-sponsor Dr. Serhan are widely recognized as experts in the fields of bacterial-epithelial-neutrophil interactions and eicosanoid biochemistry respectively. Further, both have an extensive history of successfully training developing investigators. The Environment Dr. Gewirtz has been given laboratory space in Dr. Madara´s lab in the epithelial pathobiology division of Emory University´s Pathology department. In addition to containing an extensive array of basic research equipment, this lab space contains a new thermostatted spectrofluorimeter to be used primarily by Dr. Gewirtz
Keywords: arachidonate, chemokine, gastrointestinal epithelium, secretion Salmonella typhimurium, biological signal transduction, calcium flux, inflammation, interleukin 8, neutrophil cell line, laboratory mouse, tissue /cell culture
Project start date: 2000-05-15
Project end date: 2003-02-28
5K01DK002792-02 (2001): $87858
1K01DK002792-01 (2000): $87507
Andrew T Gewirtz
Georgia State University
Project start date: 2010-04-15
Project end date: 2014-12-31
ANTIINFLAMMATORY EFFECTS OF LIPOXINS ON GUT EPITHELIA
Andrew T Gewirtz, Associate Professor
Pathologyemory University
1599 Clifton Road, 4th Floor
atlanta, Ga 30322
Grant 1F32DK009799-01 from National Institute Of Diabetes And Digestive And Kidney Diseases IRG: ZRG2
Keywords: eicosanoid, gastrointestinal epithelium biological signal transduction, cell cell interaction, mucosal immunity, neutrophil, receptor human subject, tissue /cell culture, transfection
1F32DK009799-01 (1997): $25420