title: Interleukin-18 induces production of proinflammatory cytokines in mice: no intermediate role for the cytokines of the tumor necrosis factor family and interleukin-1beta.
abstract: Interleukin-18 (IL-18) is not only a co-stimulus for the induction of interferon-gamma but also has direct proinflammatory effects by inducing tumor necrosis factor-alpha (TNF-alpha), IL-1, IL-8 and IL-6. However, the cascade of events leading to induction of cytokines by IL-18 is unclear. The aim of the present study was to investigate whether murine IL-18 stimulates production of proinflammatory cytokines, and to assess whether induction of second-wave cytokines such as IL-6 by IL-18 is driven by intermediary induction of endogenous cytokines of the TNF family or IL-1beta. When mouse peritoneal macrophages were stimulated in vitro with recombinant murine IL-18, there was a dose-dependent induction of TNF, IL-1alpha, and IL-1beta. IL-6 synthesis was also strongly induced by IL-18 and, as revealed by studies in knockout mice, this production was not dependent on interactions between endogenous cytokines of the TNF/TNF receptor family: TNF-alpha, lymphotoxin-alpha, Fas/Fas ligand (L) or CD40/CD40L. Moreover, the induction of IL-6 was also independent of endogenous IL-1beta, as macrophages isolated from IL-1beta deficient mice produced normal amounts of IL-6 after stimulation with IL-18. In conclusion, murine IL-18 has pleiotropic proinflammatory activities by inducing production of TNF-alpha, IL-1alpha, IL-1beta and IL-6, which could have important consequences for the pathophysiology of infectious and autoimmune diseases.
authors.affiliation: Department of Medicine, University Hospital Nijmegen, The Netherlands. M.Netea@aig.azn.nl
authors.forename: M G
authors.initials: MG
authors.lastname: Netea
authors.forename: B J
authors.initials: BJ
authors.lastname: Kullberg
authors.forename: I
authors.initials: I
authors.lastname: Verschueren
authors.forename: J W
authors.initials: JW
authors.lastname: Van Der Meer
mesh_terms: D000818:Animals; D016207:Cytokines / Q000096:biosynthesis* / Q000145:classification / Q000235:genetics; D004195:Disease Models, Animal; D005786:Gene Expression Regulation / Q000187:drug effects*; D007249:Inflammation / Q000235:genetics / Q000378:metabolism*; D007375:Interleukin-1 / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D020382:Interleukin-18 / Q000494:pharmacology / Q000502:physiology*; D015850:Interleukin-6 / Q000096:biosynthesis / Q000235:genetics; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D005810:Multigene Family; D011994:Recombinant Proteins / Q000494:pharmacology; D013047:Specific Pathogen-Free Organisms; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology
chemical_list: D016207:Cytokines; D007375:Interleukin-1; D020382:Interleukin-18; D015850:Interleukin-6; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha