title: Interleukin-1beta induces in vivo tolerance to lipopolysaccharide in mice.
abstract: Endotoxin or lipopolysaccharide (LPS) tolerance may be partially due to the secretion of potent anti-inflammatory cytokines following severe Gram-negative infections, or by low doses of LPS. In this work, we describe the effects of interleukin-1 (IL-1) and tumour necrosis factor alpha (TNF-), two early cytokines secreted after LPS exposure, in the induction of LPS tolerance. Our results demonstrate that mice treated with three daily doses of 100 ng of IL-1 were tolerant to LPS-induced shock. However, TNF- was unable to induce an LPS refractory state. Given the fact that 100 ng of IL-1 increase the plasma levels of glucocorticoids, we evaluated whether a daily injection of dexamethasone (DEX) alone was able to reproduce the LPS-like tolerant state. However, no signs of LPS refractoriness were detected, except when DEX was administered concomitantly with a dose of IL-1 that does not induce corticosterone secretion (12 ng/mouse). This dose was found to induce in vitro up-regulation of the glucocorticoid receptors (GcR) of peritoneal macrophages following 24 h of treatment. In addition, we demonstrate that IL-1 is capable of inducing the down-regulation of Toll-like receptor 4 (TLR4), a crucial molecule in the signal transduction of LPS. Taken together, our results indicate that IL-1 can generate tolerance to LPS in vivo, and suggest that the regulation of mechanisms of the down-regulation of TLR4, as well as those involved in the expression of GcR and/or in the secretion of glucocorticoids, would be crucial for these effects.
authors.affiliation: División Immunología, Instituto de Investigaciones Hematológicas, Academia Nacional de Medicina, Buenos Aires, Argentina. ferar@ciudad.com.ar
authors.forename: F
authors.initials: F
authors.lastname: Alves-Rosa
authors.forename: M
authors.initials: M
authors.lastname: Vulcano
authors.forename: M
authors.initials: M
authors.lastname: Beigier-Bompadre
authors.forename: G
authors.initials: G
authors.lastname: Fernández
authors.forename: M
authors.initials: M
authors.lastname: Palermo
authors.forename: M A
authors.initials: MA
authors.lastname: Isturiz
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D015536:Down-Regulation / Q000276:immunology; D029721:Drosophila Proteins; D016905:Gram-Negative Bacterial Infections / Q000276:immunology*; D007108:Immune Tolerance / Q000187:drug effects / Q000276:immunology*; D007375:Interleukin-1 / Q000276:immunology* / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D011956:Receptors, Cell Surface / Q000276:immunology; D011965:Receptors, Glucocorticoid / Q000276:immunology; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000494:pharmacology; D015854:Up-Regulation / Q000276:immunology
chemical_list: D000893:Anti-Inflammatory Agents; D029721:Drosophila Proteins; D007375:Interleukin-1; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D011965:Receptors, Glucocorticoid; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha; D003907:Dexamethasone