The intestinal epithelium and gut-associated mucosal immune system must on the one (1) hand generate an inflammatory response to pathogenic bacteria while actively limiting inflammation to commensal organisms. Inflammatory bowel disease (IBD) develops in the genetically-susceptible host following a triggering event. The first gene to be identified as a disease-susceptibility gene in Crohn's disease is CARD15/NOD2, an intracellular pathogen-recognition receptor (PRR). Crohn's disease-associated polymorphisms in the CARD15/NOD2 gene result in a protein that is impaired in its ability to activate NF-kB in response to peptidoglycan. This data suggests that a defect in the innate immune response to commensal or pathogenic bacteria may culminate in chronic intestinal inflammation. Toll-like receptors (TLRs) are also PRRs. Binding of PAMPs to their respective TLRs results in NF-kB activation and clearance of bacteria. TLR4 is the receptor for lipopolysaccharide (LPS) present on Gram-negative bacteria. This application emanates from our surprising preliminary observation that mice with a null mutation in TLR4 (TLR4-/-) have increased clinical symptoms of colitis following administration of dextran sodium sulfate, a paucity of neutrophilic infiltration, and increased bacterial translocation. Similar results were observed in MyD88-/- mice suggesting this is the dominant pathway downstream of TLR4 accounting for this phenotype. Based on our preliminary data, we wish to test the hypothesis that signaling through TLR4 is required for the generation of an acute inflammatory response to intestinal injury and limiting the development of chronic intestinal inflammation. We will use the support from this R21 to generate robust animal models that establish the requirement for TLR4 in the initiation and perpetuation of intestinal inflammation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21DK069594-01
Application #
6856432
Study Section
Special Emphasis Panel (ZRG1-GMPB (01))
Program Officer
Hamilton, Frank A
Project Start
2005-06-01
Project End
2007-05-31
Budget Start
2005-06-01
Budget End
2006-05-31
Support Year
1
Fiscal Year
2005
Total Cost
$169,500
Indirect Cost
Name
Mount Sinai School of Medicine
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
078861598
City
New York
State
NY
Country
United States
Zip Code
10029
Hernandez, Yasmin; Sotolongo, John; Breglio, Keith et al. (2010) The role of prostaglandin E2 (PGE 2) in toll-like receptor 4 (TLR4)-mediated colitis-associated neoplasia. BMC Gastroenterol 10:82
Ungaro, Ryan; Fukata, Masayuki; Hsu, David et al. (2009) A novel Toll-like receptor 4 antagonist antibody ameliorates inflammation but impairs mucosal healing in murine colitis. Am J Physiol Gastrointest Liver Physiol 296:G1167-79
Fukata, Masayuki; Hernandez, Yasmin; Conduah, Daisy et al. (2009) Innate immune signaling by Toll-like receptor-4 (TLR4) shapes the inflammatory microenvironment in colitis-associated tumors. Inflamm Bowel Dis 15:997-1006
Fukata, Masayuki; Breglio, Keith; Chen, Anli et al. (2008) The myeloid differentiation factor 88 (MyD88) is required for CD4+ T cell effector function in a murine model of inflammatory bowel disease. J Immunol 180:1886-94
Shang, Limin; Fukata, Masayuki; Thirunarayanan, Nanthakumar et al. (2008) Toll-like receptor signaling in small intestinal epithelium promotes B-cell recruitment and IgA production in lamina propria. Gastroenterology 135:529-38
Fukata, Masayuki; Chen, Anli; Vamadevan, Arunan S et al. (2007) Toll-like receptor-4 promotes the development of colitis-associated colorectal tumors. Gastroenterology 133:1869-81
Fukata, Masayuki; Chen, Anli; Klepper, Arielle et al. (2006) Cox-2 is regulated by Toll-like receptor-4 (TLR4) signaling: Role in proliferation and apoptosis in the intestine. Gastroenterology 131:862-77