The role of interleukin-1 during Pseudomonas aeruginosa bacteraemia in compromised host

Abstract number: 1733_1269

Horino T., Matsumoto T., Uramatsu M., Tanabe M., Tateda K., Miyazaki S., Aramaki Y., Iwakura Y., Yamaguchi K.

Objectives: The roles of Interleukin (IL)-1 in infectious diseases are fluctuated by the experimental conditions, especially in the difference of pathogens and immunological disorders. Therefore in this study, we evaluated the role of IL-1 in bacteraemia due to Pseudomonas aeruginosa, by comparing IL-1-deficient mice and WT (WT) mice, with or without cyclophosphamide pretreatment.

Methods:P. aeruginosa bacteraemia was induced by intravenous injection of P. aeruginosa strain D4 via retro-orbital plexus. To evaluate the role of IL-1 under various immune conditions, we used compromised host following cyclophosphamide treatment, neutropenic mice by anti-Gr-1 antibody and macrophage-depleted mice by liposomes containing dichloromethylene diphosphonate. Furthermore, to investigate bacterial clearance under macrophage-depleted condition, mice were sacrificed after bacterial inoculation, and cardiac blood, liver and spleen samples were obtained aseptically. In addition, we compared Tumour necrosis factor alpha, IL-6 and interferon-gamma productions between IL-1-deficient mice and WT mice in early and late phase sepsis.

Results: Survival rates after P. aeruginosa bacteraemia did not show significant difference between IL-1-deficient mice and WT mice. On the other hand, cyclophosphamide pretreatment in both groups of mice cause significantly higher mortality in IL-1-deficient mice compared to WT mice (P < 0.01). Bacterial counts in the blood, liver, spleen, kidney and lungs were significantly higher in IL-1-deficient mice than in WT mice following cyclophosphamide treatment. These significant differences were represented in macrophage-depleted mice, but not in neutropenic mice. Under macrophage-depleted condition, bacterial counts in blood, liver, and spleen were higher in IL-1-deficient mice than in WT mice, and Tumour necrosis factor alpha in the liver in early phase sepsis were significantly lower in IL-1-deficient mice than in WT mice.

Conclusion: Our results indicated that the role of IL-1 during bacteraemia due to P. aeruginosa was enhanced in immunocompromised conditions, especially in the devastation of macrophage functions.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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