title: Role of interleukin-18 (IL-18) during lethal shock: decreased lipopolysaccharide sensitivity but normal superantigen reaction in IL-18-deficient mice.
abstract: Lethal shock can be associated with excessive secretion of cytokines such as tumor necrosis factor (TNF) and gamma interferon (IFN-gamma). IFN-gamma 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-gamma 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-gamma in IL-18(+/+) and IL-18(-/-) mice, accompanied by an upregulation of cell surface markers CD14, CD122 (IL-2Rbeta), and CD132 (IL-2Rgamma) 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-gamma and lethality in response to LPS.
authors.affiliation: Institute of Medical Microbiology, Immunology and Hygiene, Technical University of Munich, Munich, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Hochholzer
authors.forename: G B
authors.initials: GB
authors.lastname: Lipford
authors.forename: H
authors.initials: H
authors.lastname: Wagner
authors.forename: K
authors.initials: K
authors.lastname: Pfeffer
authors.forename: K
authors.initials: K
authors.lastname: Heeg
mesh_terms: D000818:Animals; D004768:Enterotoxins / Q000633:toxicity*; D007371:Interferon-gamma / Q000378:metabolism; D020382:Interleukin-18 / Q000235:genetics*; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000633:toxicity*; D051379:Mice; D018345:Mice, Knockout; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis; D012769:Shock / Q000209:etiology / Q000401:mortality*; D018089:Superantigens / Q000633:toxicity*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D004768:Enterotoxins; D020382:Interleukin-18; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D015375:Receptors, Interleukin-2; D018089:Superantigens; D014409:Tumor Necrosis Factor-alpha; C031818:enterotoxin B, staphylococcal; D007371:Interferon-gamma