The ability of Salmonella to survive within professional phagocytes is paramount to its pathogenicity, as strains incapable of survival in mononuclear phagocytes are severely attenuated in mice. Survival of Salmonella within phagocytes is tightly associated with its ability to halt maturation of the phagosome along the endocytic pathway. We have recently discovered that Salmonella pathogenicity island 2 (SPI2)-encoded effector proteins remodel the phagosome by interfering with the TNFalpha/TNFRp55 signaling cascade that directs delivery ofNADPH oxidase-containing vesicles to the vicinity of the Salmonella phagosome. I plan to test the hypothesis that, by cleaving glucosylceramide, glucosylceramidase interferes with TNFRp55 signaling and blocks migration of NADPH oxidase-harboring vesicles to the vicinity of the Salmonella phagosome.
The specific aims are: 1) To determine the role of glucosylceramidase in the pathogenesis of Salmonella infections. Glucosylceramidase mutants will be constructed to examine the effect on both survival of Salmonella in macrophages and inhibition NADPH oxidase trafficking. 2) To examine the effect of Salmonella-encoded glucosylceramidase on macrophage lipid metabolism. Wildtype and glucosylceramidase-deficient Salmonella will be used to infect macrophages to assess global changes in the sphingomyelin pathway. Purified glucosylceramidase will be tested for lipid metabolizing activity, and immunocytochemistry will be used to visualize the effect of glycosylceramidase on trafficking of NADPH oxidase-containing vesicles. 3) To determine the role of glucosylceramidase on avoiding IFN( activated trafficking of NADPH oxidase. In this section, I will elucidate the mechanisms by which IFN gamma stimulates anti-Salmonella activity dependent upon the NADPH oxidase. The ability of IFNgamma to stimulate glucosylceramide synthesis will be examined as well. These studies will not only enhance our understanding of Salmonella pathogenesis but will also identify potential targets for the development of new therapeutic strategies against intracellular pathogens.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Clinical Investigator Award (CIA) (K08)
Project #
1K08AI053213-01A1
Application #
6721064
Study Section
Microbiology and Infectious Diseases B Subcommittee (MID)
Program Officer
Alexander, William A
Project Start
2004-07-01
Project End
2009-03-31
Budget Start
2004-07-01
Budget End
2005-03-31
Support Year
1
Fiscal Year
2004
Total Cost
$114,480
Indirect Cost
Name
University of Colorado Denver
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
041096314
City
Aurora
State
CO
Country
United States
Zip Code
80045
McCollister, Bruce D; Hoffman, Matthew; Husain, Maroof et al. (2011) Nitric oxide protects bacteria from aminoglycosides by blocking the energy-dependent phases of drug uptake. Antimicrob Agents Chemother 55:2189-96
Husain, Maroof; Jones-Carson, Jessica; Song, Miryoung et al. (2010) Redox sensor SsrB Cys203 enhances Salmonella fitness against nitric oxide generated in the host immune response to oral infection. Proc Natl Acad Sci U S A 107:14396-401
McCollister, Bruce D; Myers, Jesse T; Jones-Carson, Jessica et al. (2007) Constitutive acid sphingomyelinase enhances early and late macrophage killing of Salmonella enterica serovar Typhimurium. Infect Immun 75:5346-52
McCollister, Bruce D; Myers, Jesse T; Jones-Carson, Jessica et al. (2007) N(2)O(3) enhances the nitrosative potential of IFNgamma-primed macrophages in response to Salmonella. Immunobiology 212:759-69
Jones-Carson, Jessica; McCollister, Bruce D; Clambey, Eric T et al. (2007) Systemic CD8 T-cell memory response to a Salmonella pathogenicity island 2 effector is restricted to Salmonella enterica encountered in the gastrointestinal mucosa. Infect Immun 75:2708-16
McCollister, Bruce D; Bourret, Travis J; Gill, Ronald et al. (2005) Repression of SPI2 transcription by nitric oxide-producing, IFNgamma-activated macrophages promotes maturation of Salmonella phagosomes. J Exp Med 202:625-35