title: Role of NF-kappaB and PI 3-kinase/Akt in TNF-alpha-induced cytotoxicity in microvascular endothelial cells.
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.
authors.affiliation: Department of Medicine, University of Colorado at Denver and Health Sciences Center, Box B173, 4200 E 9th Ave., Denver, CO 80262, USA.
authors.forename: Zhu
authors.initials: Z
authors.lastname: Zhou
authors.forename: Patricia
authors.initials: P
authors.lastname: Gengaro
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Xue-qing
authors.initials: XQ
authors.lastname: Wang
authors.forename: Chunling
authors.initials: C
authors.lastname: Li
authors.forename: Sarah
authors.initials: S
authors.lastname: Faubel
authors.forename: Christopher
authors.initials: C
authors.lastname: Rivard
authors.forename: Robert W
authors.initials: RW
authors.lastname: Schrier
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019446:Endotoxemia / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053583:Interleukin-1beta / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011392:Proline / Q000031:analogs & derivatives / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D018805:Sepsis / Q000378:metabolism; D013859:Thiocarbamates / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D002867:Chromones; D004791:Enzyme Inhibitors; D053583:Interleukin-1beta; D015850:Interleukin-6; D009025:Morpholines; D016328:NF-kappa B; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011392:Proline; D051057:Proto-Oncogene Proteins c-akt; D013859:Thiocarbamates; D014409:Tumor Necrosis Factor-alpha; C066229:prolinedithiocarbamate; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C496317:Nos2 protein, mouse