Role of Interleukin-18 (IL-18) during Lethal Shock: Decreased Lipopolysaccharide Sensitivity but Normal Superantigen Reaction in IL-18-Deficient Mice
AUTOR(ES)
Hochholzer, Peter
FONTE
American Society for Microbiology
RESUMO
Lethal shock can be associated with excessive secretion of cytokines such as tumor necrosis factor (TNF) and gamma interferon (IFN-γ). IFN-γ mediates macrophage activation and appears to be controlled by interleukin (IL)-12 and IL-18. To investigate the role of IL-18 in vivo, we generated IL-18-deficient mice by gene targeting. IL-18−/− mice showed decreased sensitivity towards lipopolysaccharide (LPS)-induced shock. LPS-induced IFN-γ production was abrogated, yet induction of IL-12 and TNF was not affected. Both wild-type and IL-18-deficient mice succumbed to LPS-induced lethal shock after sensitization with d-galactosamine. However, in marked contrast to LPS, the bacterial superantigen Staphylococcus aureus enterotoxin B (SEB) induced comparable serum levels of IFN-γ in IL-18+/+ and IL-18−/− mice, accompanied by an upregulation of cell surface markers CD14, CD122 (IL-2Rβ), and CD132 (IL-2Rγ) on peritoneal macrophages. Moreover, SEB injection rendered IL-18-deficient mice sensitive for subsequent challenge with LPS. The degree of sensitization was comparable to that in wild-type controls with respect to lethality. However, LPS-induced TNF levels in serum were significantly reduced in SEB-sensitized IL-18-deficient mice. These results imply that IL-18 plays an important role in induction of IFN-γ and lethality in response to LPS.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=97635Documentos Relacionados
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