Hyperketonemia increases tumor necrosis factor-alpha secretion in cultured U937 monocytes and Type 1 diabetic patients and is apparently mediated by oxidative stress and cAMP deficiency.
An elevated blood level of tumor necrosis factor (TNF)-alpha is a validated marker of vascular inflammation, which can result in the development of vascular disease and atherosclerosis. This study examined the hypothesis that ketosis increases the TNF-alpha secretion, both in a cell culture model using U937 monocytes and in type 1 diabetic patients in vivo. U937 cells were cultured with ketone bodies (acetoacetate [AA] and beta-hydroxybutyrate [BHB]) in the presence or absence of high levels of glucose in medium at 37 degrees C for 24 h. This study demonstrates the following points. First, hyperketonemic diabetic patients have significantly higher levels of TNF-alpha than normoketonemic diabetic patients (P < 0.01) and normal control subjects (P < 0.01). There was a significant correlation (r = 0.36, P < 0.05; n = 34) between ketosis and oxidative stress as well as between oxidative stress and TNF-alpha levels (r = 0.47, P < 0.02; n = 34) in the blood of diabetic patients. Second, ketone body AA treatment increases TNF-alpha secretion, increases oxygen radicals production, and lowers cAMP levels in U937 cells. However, BHB did not have any effect on TNF-alpha secretion or oxygen radicals production in U937 cells. Third, exogenous addition of dibutyryl cAMP, endogenous stimulation of cAMP production by forskolin, and antioxidant N-acetylcysteine (NAC) prevented stimulation of TNF-alpha secretion caused by AA alone or with high glucose. Similarly, NAC prevented the elevation of TNF-alpha secretion and lowering of cAMP levels in H(2)O(2)-treated U937 cells. Fourth, the effect of AA on TNF-alpha secretion was inhibited by specific inhibitors of protein kinase A (H89), p38-mitogen-activated protein kinase (SB203580), and nuclear transcription factor (NF)kappaB (NFkappaB-SN50). This study demonstrates that hyperketonemia increases TNF-alpha secretion in cultured U937 monocytic cells and TNF-alpha levels in the blood of type 1 diabetic patients and is apparently mediated by AA-induced cellular oxidative stress and cAMP deficiency.
Jain
Sushil K
SK
Department of Pediatrics, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130, USA. sjain@lsuhsc.edu
Kannan
Krishnaswamy
K
Lim
Gideon
G
McVie
Robert
R
Bocchini
Joseph A
JA
D020155:3-Hydroxybutyric Acid / Q000494:pharmacology*; D000090:Acetoacetates / Q000494:pharmacology*; D000111:Acetylcysteine / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology*; D000242:Cyclic AMP / Q000097:blood / Q000502:physiology*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000503:physiopathology*; D006801:Humans; D007657:Ketone Bodies / Q000097:blood*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects / Q000502:physiology*; D018384:Oxidative Stress / Q000502:physiology*; D011493:Protein Kinase C / Q000097:blood; D012016:Reference Values; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D020298:U937 Cells
D000090:Acetoacetates; D000975:Antioxidants; D007657:Ketone Bodies; D014409:Tumor Necrosis Factor-alpha; C016635:acetoacetic acid; D000242:Cyclic AMP; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate; D020155:3-Hydroxybutyric Acid; D000111:Acetylcysteine