title: Inhibition of NF-kappaB activity prevents downregulation of alpha1-adrenergic receptors and circulatory failure during CLP-induced sepsis.
abstract: The reduced pressure response to norepinephrine during sepsis has directed our interest to the regulation of alpha1-adrenergic receptors. Because nuclear factor (NF)-kappaB occupies a prominent role in the inflammatory cascade, we hypothesized that NF-kappaB downregulates alpha1-receptors by liberation of proinflammatory cytokines and thereby contributes to septic circulatory failure. Sepsis was induced by cecal ligation and puncture (CLP) in wild-type mice and mice with deficiencies for proinflammatory cytokines, and mice were injected with TNF-alpha, IL-1beta, IFN-gamma, or IL-6. Animals were treated with glucocorticoids or small interfering RNA (siRNA) targeting multiple cytokines and NF-kappaB. Vascular smooth muscle cells were incubated with cytokines and calcium mobilization, mRNA stability assays, and promoter studies with alpha1-promoter-luciferase constructs were performed. Cecal ligation and puncture treatment resulted in a hyperdynamic circulatory failure, diminished calcium response to norepinephrine, and a significant downregulation of alpha1-receptors. Proinflammatory cytokines also downregulated alpha1-receptors by suppressing promoter activity at the level of gene transcription. However, suppression of single proinflammatory cytokines in cytokine knockout mice did not diminish CLP-induced downregulation of alpha1-receptors. In contrast, blocking multiple cytokines via siRNA pretreatment or glucocorticoid administration attenuated CLP-induced cardiovascular failure and downregulation of alpha1-receptors. Furthermore, inhibiting NF-kappaB activity by siRNA reduced the production of cytokines, prevented circulatory failure and downregulation of alpha1-receptors, and improved survival of septic mice. Our findings indicate that NF-kappaB has a central role in augmenting proinflammatory cytokine production during sepsis, which in turn downregulates alpha1-receptor expression. Our data further define a critical role for NF-kappaB in the pathogenesis of septic shock, indicating that targeting NF-kappaB is a desired therapeutic strategy to treat septic vasoplegia.
authors.affiliation: Department of Anesthesiology, University of Regensburg, Franz-Josef-Strauss, Regensburg, Germany. christoph_schmidt2001@yahoo.de
authors.forename: Christoph
authors.initials: C
authors.lastname: Schmidt
authors.forename: Birgül
authors.initials: B
authors.lastname: Kurt
authors.forename: Klaus
authors.initials: K
authors.lastname: Höcherl
authors.forename: Michael
authors.initials: M
authors.lastname: Bucher
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002432:Cecum / Q000293:injuries*; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation / Q000187:drug effects; D006439:Hemodynamics; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D008026:Ligation; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016328:NF-kappa B / Q000235:genetics / Q000502:physiology*; D020871:RNA Stability / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D018340:Receptors, Adrenergic, alpha-1 / Q000235:genetics / Q000378:metabolism*; D018805:Sepsis / Q000209:etiology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D007375:Interleukin-1; D015850:Interleukin-6; D016328:NF-kappa B; D034741:RNA, Small Interfering; D018340:Receptors, Adrenergic, alpha-1; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma