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IL-10 improves lung injury and survival in Pseudomonas aeruginosa pneumonia
T Sawa1, D B Corry, M A Gropper
1Department of Anesthesia, University of California, San Francisco 94143, USA.
Abstract:
Pseudomonas aeruginosa is the most frequent Gram-negative pathogen causing nosocomial pneumonia. Four different strains of P. aeruginosa (including three isogenic transposon mutants) were utilized in experiments in mice to characterize the specific patterns of cytokine generation in response to bacterial products and cytotoxicity. Intratracheal instillation of any of the strains led to the up-regulation of IL-1beta, IL-6, and TNF-alpha mRNA. Instillation of the cytotoxic strains (PA103, PA103tox::omega) led to IL-10 mRNA up-regulation in the lungs and increased concentrations of IL-10 in the blood. In contrast, the instillation of the noncytotoxic strains (PA01, PA103exsA::omega) did not lead to an increase in IL-10 mRNA in the lungs or to an increase of IL-10 concentration in blood. IL-10 production appears to be a response to either cellular injury or to specific cytotoxic exoproducts produced by the bacteria. The systemic administration of rIL-10 significantly decreased the lung injury and the mortality in mice who had received the cytotoxic strains. The improvement in survival induced by administration of rIL-10 required the concomitant presence of IFN-gamma, as blockade of IFN-gamma with a neutralizing Ab led to 100% mortality, despite the administration of rIL-10. These results suggest that IL-10 is produced in response to specific bacterial products and that there is a potential role for IL-10 in the treatment of cytotoxic P. aeruginosa pneumonia.
Insights
Cytotoxic Pseudomonas aeruginosa strains trigger Interleukin-10 (IL-10) production in mice, which is crucial for reducing lung injury and mortality. This suggests IL-10 may be a potential treatment for P. aeruginosa pneumonia.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- Pseudomonas aeruginosa is a leading cause of hospital-acquired pneumonia.
- Understanding host immune responses to P. aeruginosa is critical for developing effective treatments.
Purpose of the Study:
- To investigate cytokine generation patterns in response to different P. aeruginosa strains.
- To explore the role of Interleukin-10 (IL-10) in P. aeruginosa-induced pneumonia and its potential therapeutic applications.
Main Methods:
- Intratracheal instillation of four P. aeruginosa strains (including isogenic mutants) in a mouse model.
- Quantification of cytokine mRNA (IL-1beta, IL-6, TNF-alpha, IL-10) in lung tissue.
- Measurement of IL-10 blood concentrations.
- Administration of recombinant IL-10 (rIL-10) and IFN-gamma blockade to assess therapeutic effects.
Main Results:
- All P. aeruginosa strains induced IL-1beta, IL-6, and TNF-alpha mRNA.
- Cytotoxic strains PA103 and PA103tox::omega significantly increased IL-10 mRNA and blood IL-10 levels.
- Non-cytotoxic strains PA01 and PA103exsA::omega did not elevate IL-10.
- Systemic rIL-10 administration reduced lung injury and mortality in mice infected with cytotoxic strains.
- Therapeutic effect of rIL-10 was dependent on the presence of Interferon-gamma (IFN-gamma).
Conclusions:
- IL-10 production is a specific response to cytotoxic P. aeruginosa strains or their products.
- IL-10 plays a protective role in P. aeruginosa pneumonia, mitigating lung injury and mortality.
- Combined IL-10 and IFN-gamma may offer a therapeutic strategy for treating severe P. aeruginosa infections.