High-glucose-induced nuclear factor kappaB activation in vascular smooth muscle cells.
OBJECTIVE
Vascular smooth muscle cell (VSMC) dysfunction plays a role in diabetic macrovasculopathy. This dysfunction may be caused or exacerbated by expression of many of genes potently activated by the transcriptional factor nuclear factor kappaB (NF-kappaB). We have examined whether culture of VSMCs under high glucose conditions to stimulate the diabetic state can lead to the activation of NF-kappaB.


METHODS
NF-kappaB activation was assessed in VSMCs stably transfected with a cis-reporter plasmid containing the NF-kappaB binding sites.


RESULTS
Within 3-h incubation, high glucose (27.5 or 55 mmol/l) alone induced an increase in NF-kappaB activity in VSMCs; this increase was mimicked by mannitol given to deliver the same osmolar stress to the cells. High glucose or mannitol also enhanced TNFalpha-stimulated NF-kappaB activity. Incubation with high glucose for 48 h followed by stimulation with TNFalpha led to a marked potentiation of NF-kappaB activation compared with normoglycemic (5.5 mmol/l) VSMCs exposed to TNFalpha, while mannitol attenuated this effect. A 48-h incubation with high glucose substantially reduced glutathione (GSH) levels compared with normoglycemic VSMCs, whereas mannitol significantly increased GSH levels. An antioxidant N-acetyl-L-cysteine and a selective protein kinase C (PKC) inhibitor GF109203X significantly suppressed the TNFalpha-induced NF-kappaB activation, and abrogated potentiation of TNFalpha-induced NF-kappaB activity caused by high glucose (27.5 mmol/l).


CONCLUSIONS
These results suggest that acutely high glucose causes alterations in osmolarity leading to activation of NF-kappaB, but that exposure to high glucose for more prolonged times causes changes in antioxidant defences and activation of PKC, which potentiates cytokine activation of NF-kappaB. Further definition of these pathways will help to delineate important signals mediating the aberrant behavior of VSMCs under hyperglycemic/diabetic conditions.
Hattori
Y
Y
Department of Endocrinology, Dokkyo University School of Medicine, Mibu, Tochigi, Japan.
Hattori
S
S
Sato
N
N
Kasai
K
K
D000111:Acetylcysteine / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002478:Cells, Cultured; D003925:Diabetic Angiopathies / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008301:Maleimides / Q000494:pharmacology; D008353:Mannitol / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D051381:Rats; D017208:Rats, Wistar; D013268:Stimulation, Chemical; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000975:Antioxidants; D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D008353:Mannitol; D011493:Protein Kinase C; D005978:Glutathione; D005947:Glucose; C070515:bisindolylmaleimide I; D000111:Acetylcysteine