Role of NF-kappaB and PI 3-kinase/Akt in TNF-alpha-induced cytotoxicity in microvascular endothelial cells

Am J Physiol Renal Physiol. 2008 Oct;295(4):F932-41. doi: 10.1152/ajprenal.00066.2008. Epub 2008 Jul 16.

Abstract

The interaction of tumor necrosis factor (TNF)-alpha with the endothelium is a pivotal factor during endotoxemia. Inflammatory conditions are characterized by the activation of the transcription factor NF-kappaB and the expression of inflammatory mediators. Previous reports indicate that inhibition of NF-kappaB activation during sepsis may be beneficial to the microvasculature. In addition, the phosphatidylinositol-3-kinase/Akt signaling pathway (PI3-kinase/Akt) has been shown to be cytoprotective. In this study, we examined the effect of inhibition of NF-kappaB and PI3-kinase/Akt on cell viability, cytokine production, inducible nitric oxide synthase (iNOS) expression, and nitric oxide (NO) generation by TNF-alpha-treated cultured microvascular endothelial cells. TNF-alpha induced significant cytotoxicity and was associated with increased inflammatory cytokines and NO and increased expression of iNOS. The NF-kappaB inhibitor, pyrrolidine dithiocarbamate (PDTC), prevented these increases and significantly attenuated the TNF-alpha-induced cytotoxicity. TNF-alpha also caused PI3-kinase/Akt activation, which was further increased by PDTC and prevented by the PI3-kinase inhibitor, LY294002. Inhibition of PI3-kinase/Akt also significantly potentiated TNF-alpha-mediated cytotoxicity. LY294002 treatment resulted in the appearance of increased apoptosis, compatible with the known anti-apoptotic properties of PI3-kinase/Akt. The present results therefore demonstrate a cytotoxic effect of TNF-alpha in microvascular endothelial cells which can be attenuated by NF-kappaB inhibition. In addition, PI3-kinase/Akt activation during TNF-alpha exposure may represent a compensatory anti-necrotic and anti-apoptotic pathway. The cytoprotective effects of NF-kappaB inhibition and PI3-kinase/Akt activation may have potential implications in the treatment of endotoxemia and septic shock.

MeSH terms

  • Animals
  • Antioxidants / pharmacology
  • Cell Survival / drug effects
  • Cell Survival / physiology
  • Cells, Cultured
  • Chromones / pharmacology
  • Endothelial Cells / cytology
  • Endothelial Cells / drug effects
  • Endothelial Cells / metabolism*
  • Endotoxemia / metabolism*
  • Enzyme Inhibitors / pharmacology
  • Interleukin-1beta / metabolism
  • Interleukin-6 / metabolism
  • MAP Kinase Signaling System / drug effects
  • MAP Kinase Signaling System / physiology
  • Mice
  • Morpholines / pharmacology
  • NF-kappa B / antagonists & inhibitors
  • NF-kappa B / metabolism*
  • Nitric Oxide / metabolism
  • Nitric Oxide Synthase Type II / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoinositide-3 Kinase Inhibitors
  • Proline / analogs & derivatives
  • Proline / pharmacology
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Sepsis / metabolism
  • Thiocarbamates / pharmacology
  • Tumor Necrosis Factor-alpha / metabolism
  • Tumor Necrosis Factor-alpha / toxicity*

Substances

  • Antioxidants
  • Chromones
  • Enzyme Inhibitors
  • Interleukin-1beta
  • Interleukin-6
  • Morpholines
  • NF-kappa B
  • Phosphoinositide-3 Kinase Inhibitors
  • Thiocarbamates
  • Tumor Necrosis Factor-alpha
  • prolinedithiocarbamate
  • Nitric Oxide
  • 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
  • Proline
  • Nitric Oxide Synthase Type II
  • Nos2 protein, mouse
  • Proto-Oncogene Proteins c-akt