title: IL-1 receptor-associated kinase modulates host responsiveness to endotoxin.
abstract: Endotoxin triggers many of the inflammatory, hemodynamic, and hematological derangements of Gram-negative septic shock. Recent genetic studies in mice have identified the Toll-like receptor 4 as the transmembrane endotoxin signal transducer. The IL-1 intracellular signaling pathway has been implicated in Toll-like receptor signal transduction. LPS-induced activation of the IL-1 receptor-associated kinase (IRAK), and the influence of IRAK on intracellular signaling and cellular responses to endotoxin has not been explored in relevant innate immune cells. We demonstrate that LPS activates IRAK in murine macrophages. IRAK-deficient macrophages, in contrast, are resistant to LPS. Deletion of IRAK disrupts several endotoxin-triggered signaling cascades. Furthermore, macrophages lacking IRAK exhibit impaired LPS-stimulated TNF-alpha production, and IRAK-deficient mice withstand the lethal effects of LPS. These findings, coupled with the critical role for IRAK in IL-1 and IL-18 signal transduction, demonstrate the importance of this kinase and the IL-1/Toll signaling cassette in sensing and responding to Gram-negative infection.
authors.affiliation: Departments of Pharmacology, Pediatrics, and Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Swantek
authors.forename: M F
authors.initials: MF
authors.lastname: Tsen
authors.forename: M H
authors.initials: MH
authors.lastname: Cobb
authors.forename: J A
authors.initials: JA
authors.lastname: Thomas
mesh_terms: D000818:Animals; D004789:Enzyme Activation / Q000276:immunology; D051550:I-kappa B Kinase; D007113:Immunity, Innate; D053592:Interleukin-1 Receptor-Associated Kinases; D007928:Lethal Dose 50; D008070:Lipopolysaccharides / Q000633:toxicity*; D020935:MAP Kinase Signaling System / Q000276:immunology; D008264:Macrophages / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016328:NF-kappa B / Q000378:metabolism / Q000502:physiology; D011494:Protein Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism / Q000502:physiology; D017472:Receptors, Interleukin-1 / Q000502:physiology*; D012772:Shock, Septic / Q000235:genetics / Q000276:immunology / Q000401:mortality; D015398:Signal Transduction / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D008070:Lipopolysaccharides; D016328:NF-kappa B; D017472:Receptors, Interleukin-1; D014409:Tumor Necrosis Factor-alpha; D011494:Protein Kinases; D053592:Interleukin-1 Receptor-Associated Kinases; D017346:Protein Serine-Threonine Kinases; C496564:Chuk protein, mouse; D051550:I-kappa B Kinase; C496562:Ikbkb protein, mouse; C496566:Ikbke protein, mouse