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: Christoph Schmidt, Birgül Kurt, Klaus Höcherl, Michael Bucher
• Journal: Shock (Augusta, Ga.) (Shock) Vol. 32 Issue 3 Pg. 239-46 (Sep 2009) ISSN: 1540-0514 [Electronic] United States
• PMID: 19106815 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Interleukin-1
• Interleukin-6
• NF-kappa B
• RNA, Small Interfering
• Receptors, Adrenergic, alpha-1
• Tumor Necrosis Factor-alpha
• Interferon-gamma

Topics

• Animals
• Blotting, Western
• Cecum (injuries)
• Cells, Cultured
• Enzyme-Linked Immunosorbent Assay
• Gene Expression Regulation (drug effects)
• Hemodynamics
• Interferon-gamma (pharmacology)
• Interleukin-1 (pharmacology)
• Interleukin-6 (pharmacology)
• Ligation
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• NF-kappa B (genetics, physiology)
• RNA Stability (genetics)
• RNA, Small Interfering (genetics)
• Receptors, Adrenergic, alpha-1 (genetics, metabolism)
• Sepsis (etiology, metabolism)
• Tumor Necrosis Factor-alpha (pharmacology)