Patients with cystic fibrosis (CF) develop persistent inflammation and chronic infections with Pseudomonas aeruginosa that ultimately result in their death. Toll-like receptors (TLRs) are type-I transmembrane proteins that transduce signals triggering the inflammatory and innate immune response to a variety of pathogens. TLR4, in concert with a co-receptor, MD-2, has been shown to mediate responses to lipopolysaccharide (LPS), a pro-inflammatory component of Gram-negative bacteria. This proposal will address the role that TLR4 plays in the pulmonary immune and inflammatory response to P. aeruginosa. The rationale for these studies derives from several novel observations made by our group. We have found that the structure of P. aeruginosa LPS isolated from CF patients is distinct from that of P. aeruginosa isolated from non-CF patients. Our preliminary in vitro data suggest that there are differences in the recognition of P. aeruginosa LPS by murine (mu) as compared to human (hu) TLR4. Specifically, muTLR4 mediates equivalent responses to both LPS from CF strains (CF-specific LPS) and non-CF strains (unmodified LPS) of P. aeruginosa, whereas huTLR4 responds much more poorly to non-CF than CF LPS. We hypothesize that CF LPS directly contributes to the chronic inflammation seen in CF and does so in part due to the unique recognition specificity of huTLR4, which recognizes and responds to CF LPS much more intensely than to unmodified LPS. The rapid and intense inflammatory response to P. aeruginosa in mouse lungs has limited the usefulness of mouse models for CF, possibly due to the more efficient recognition of unmodified LPS by muTLR4. We therefore propose to engineer a mouse that will mimic the decreased responsiveness of huTLR4 to unmodified LPS in order to evaluate the role that TLR4 plays in the immune response to P. aeruginosa.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL069503-01
Application #
6442681
Study Section
Special Emphasis Panel (ZHL1-CSR-P (S1))
Program Officer
Musson, Robert
Project Start
2001-09-30
Project End
2005-07-31
Budget Start
2001-09-30
Budget End
2002-07-31
Support Year
1
Fiscal Year
2001
Total Cost
$303,867
Indirect Cost
Name
University of Washington
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
135646524
City
Seattle
State
WA
Country
United States
Zip Code
98195
Hajjar, Adeline M; Ernst, Robert K; Fortuno 3rd, Edgardo S et al. (2012) Humanized TLR4/MD-2 mice reveal LPS recognition differentially impacts susceptibility to Yersinia pestis and Salmonella enterica. PLoS Pathog 8:e1002963
Kollmann, Tobias R; Reikie, Brian; Blimkie, Darren et al. (2007) Induction of protective immunity to Listeria monocytogenes in neonates. J Immunol 178:3695-701
Skerrett, Shawn J; Wilson, Christopher B; Liggitt, H Denny et al. (2007) Redundant Toll-like receptor signaling in the pulmonary host response to Pseudomonas aeruginosa. Am J Physiol Lung Cell Mol Physiol 292:L312-22
Krishnegowda, Gowdahalli; Hajjar, Adeline M; Zhu, Jianzhong et al. (2005) Induction of proinflammatory responses in macrophages by the glycosylphosphatidylinositols of Plasmodium falciparum: cell signaling receptors, glycosylphosphatidylinositol (GPI) structural requirement, and regulation of GPI activity. J Biol Chem 280:8606-16
Hajjar, Adeline M; Harowicz, Heidi; Liggitt, H Denny et al. (2005) An essential role for non-bone marrow-derived cells in control of Pseudomonas aeruginosa pneumonia. Am J Respir Cell Mol Biol 33:470-5
Skerrett, Shawn J; Liggitt, H Denny; Hajjar, Adeline M et al. (2004) Cutting edge: myeloid differentiation factor 88 is essential for pulmonary host defense against Pseudomonas aeruginosa but not Staphylococcus aureus. J Immunol 172:3377-81
Skerrett, Shawn J; Liggitt, H Denny; Hajjar, Adeline M et al. (2004) Respiratory epithelial cells regulate lung inflammation in response to inhaled endotoxin. Am J Physiol Lung Cell Mol Physiol 287:L143-52
Way, Sing Sing; Thompson, Lucas J; Lopes, Jared E et al. (2004) Characterization of flagellin expression and its role in Listeria monocytogenes infection and immunity. Cell Microbiol 6:235-42
Ernst, Robert K; Hajjar, Adeline M; Tsai, Jeff H et al. (2003) Pseudomonas aeruginosa lipid A diversity and its recognition by Toll-like receptor 4. J Endotoxin Res 9:395-400
Way, Sing Sing; Kollmann, Tobias R; Hajjar, Adeline M et al. (2003) Cutting edge: protective cell-mediated immunity to Listeria monocytogenes in the absence of myeloid differentiation factor 88. J Immunol 171:533-7

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