The central goal of this project is to gain a better understanding of the pathogenesis of and immunity to infections caused by LPS-smooth strains P. aeruginosa strains in immunocompromised patients. Based on previous studies by the sponsor's laboratory and collaborators, we have established a reproducible mouse model of P. aeruginosa gastrointestinal-colonization and systemic spread during neutropenia. Preliminary studies using this model have identified several factors that are necessary for gastrointestinal colonization and dissemination. Of note, virulence factors expected to play an important role in colonization, namely pill and flagella, were not needed whereas LPS-outer core polysaccharide and O-side chains were. The duration and intensity of neutropenia, related to cyclophosphamide dose, was important in identifying virulence factors needed for dissemination. These preliminary experiments have led to the following testable hypothesis: Surface factors of P. aeruginosa needed to colonize the gastrointestinal mucosa and to translocate and cause bacteremia are not fully known. Identification of such factors can be accomplished in a murine model that will define both pathogen virulence factors (colonization and translocation factors) and host immune responses (cellular and humoral immune effectors). The findings could lead to means to effectively disrupt mucosal colonization and dissemination and diminish the impact of P. aeruginosa infection in immunocompromised hosts.
In Aim 1, virulence factors needed by P. aeruginosa to establish gastrointestinal colonization, translocation, and dissemination will be identified by use of microarray and TraSH (transposon site hybridization) technology, and mutants will be created for testing in the colonization/dissemination model.
In Aim 2, the role of host immune effectors (cellular and humoral innate immunity) that are necessary for preventing P. aeruginosa colonization and dissemination will be further delineated. The candidate seeks an intensive, formal, and mentored training to provide the necessary intellectual and technical tools to achieve independence as a scientist. As a specialist in pediatric hematology/oncology and infectious diseases, his long-term goal is to develop strategies and potential therapies to prevent or ameliorate the consequences of P. aeruginosa infections.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Clinical Investigator Award (CIA) (K08)
Project #
5K08AI062983-04
Application #
7389572
Study Section
Microbiology and Infectious Diseases B Subcommittee (MID)
Program Officer
Korpela, Jukka K
Project Start
2005-04-01
Project End
2010-03-31
Budget Start
2008-04-01
Budget End
2009-03-31
Support Year
4
Fiscal Year
2008
Total Cost
$128,120
Indirect Cost
Name
Brigham and Women's Hospital
Department
Type
DUNS #
030811269
City
Boston
State
MA
Country
United States
Zip Code
02115
Lopez-Medina, Eduardo; Neubauer, Megan M; Pier, Gerald B et al. (2011) RNA isolation of Pseudomonas aeruginosa colonizing the murine gastrointestinal tract. J Vis Exp :
Kamei, Akinobu; Koh, Andrew Y; Gadjeva, Mihaela et al. (2010) Analysis of acquisition of Pseudomonas aeruginosa gastrointestinal mucosal colonization and horizontal transmission in a murine model. J Infect Dis 201:71-80
Koh, Andrew Y; Mikkelsen, Per J; Smith, Roger S et al. (2010) Utility of in vivo transcription profiling for identifying Pseudomonas aeruginosa genes needed for gastrointestinal colonization and dissemination. PLoS One 5:e15131
Koh, Andrew Y; Priebe, Gregory P; Ray, Christopher et al. (2009) Inescapable need for neutrophils as mediators of cellular innate immunity to acute Pseudomonas aeruginosa pneumonia. Infect Immun 77:5300-10
Van Gennip, Maria; Christensen, Louise Dahl; Alhede, Morten et al. (2009) Inactivation of the rhlA gene in Pseudomonas aeruginosa prevents rhamnolipid production, disabling the protection against polymorphonuclear leukocytes. APMIS 117:537-46
Koh, Andrew Y; Kohler, Julia R; Coggshall, Kathleen T et al. (2008) Mucosal damage and neutropenia are required for Candida albicans dissemination. PLoS Pathog 4:e35