Induction of interleukin-10 and down-regulation of cytokine production by Klebsiella pneumoniae capsule in mice with pulmonary infection

J Med Microbiol. 2001 May;50(5):456-461. doi: 10.1099/0022-1317-50-5-456.


The role of the capsule of Klebsiella pneumoniae in inducing cytokine production was investigated by comparing the responses of mice with experimentally induced pneumonia caused by capsulate (strain DT-S) or non-capsulate (mutant strain DT-X) K. pneumoniae. Anaesthetised ICR mice were inoculated intranasally. Whereas all DT-S-infected mice died within 3 days, no deaths were observed in DT-X-infected mice by 14 days after infection. During the early stage of infection, interferon-gamma (IFN-gamma) levels in bronchoalveolar lavage fluid (BALF) of DT-X-infected mice were significantly higher than those in DT-S-infected mice. In contrast, in the late stage of infection, serum levels of granulocyte macrophage-colony stimulating factor (GM-CSF) and IFN-gamma in DT-S-infected mice were significantly higher than those in DT-X-infected mice. Levels of interleukin10 (IL-10) in BALF and serum of DT-S-infected mice were significantly and persistently higher than those of DT-X-infected mice. The IL-10/TNF-alpha (tumour necrosis factor-a) ratios in BALF and serum indicated that higher levels of IL-10 production were induced in mice infected with strain DT-S than in those infected with strain DT-X. The results suggest that the capsule of K. pneumoniae may induce IL-10 production at the site of infection and, thereafter, these high IL-10 levels may serve to down-regulate the expression of pro-inflammatory cytokines.

MeSH terms

  • Animals
  • Bacterial Capsules / physiology*
  • Bronchoalveolar Lavage Fluid / chemistry
  • Cytokines / blood
  • Cytokines / metabolism*
  • Down-Regulation
  • Granulocyte-Macrophage Colony-Stimulating Factor / blood
  • Granulocyte-Macrophage Colony-Stimulating Factor / metabolism
  • Interferon-gamma / blood
  • Interferon-gamma / metabolism
  • Interleukin-10 / blood
  • Interleukin-10 / metabolism*
  • Kinetics
  • Klebsiella Infections / metabolism
  • Klebsiella Infections / microbiology
  • Klebsiella pneumoniae / physiology*
  • Lung / metabolism
  • Lung / microbiology*
  • Lung / pathology
  • Lung Diseases / microbiology
  • Lung Diseases / mortality
  • Lung Diseases / pathology
  • Male
  • Mice
  • Mice, Inbred ICR
  • Specific Pathogen-Free Organisms
  • Survival Analysis
  • Survival Rate
  • Time Factors
  • Tumor Necrosis Factor-alpha / metabolism


  • Cytokines
  • Tumor Necrosis Factor-alpha
  • Interleukin-10
  • Interferon-gamma
  • Granulocyte-Macrophage Colony-Stimulating Factor