Hyperketonemia Increases Tumor Necrosis Factor-α Secretion in Cultured U937 Monocytes and Type 1 Diabetic Patients and Is Apparently Mediated by Oxidative Stress and cAMP Deficiency

Jain, Sushil K.; Kannan, K.; Lim, Gideon; McVie, Robert; Bocchini, Joseph A.

doi:10.2337/diabetes.51.7.2287

Cited by 106 publications

(79 citation statements)

References 50 publications

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“…Culture of human myelocytic cell line (U937 cells). This leukocytic cell line (25) was cultured in glucose-free RPMI medium (Sigma, Poole, U.K.), as previously described (10). For experimentation, the cells were centrifuged, washed in PBS, and exposed to 5% plasma in RPMI from either diabetic patients or age-matched control subjects.…”

Section: Methodsmentioning

confidence: 99%

Tumor Necrosis Factor-α in Diabetic Plasma Increases the Activity of Core 2 GlcNAc-T and Adherence of Human Leukocytes to Retinal Endothelial Cells

Ben-Mahmud

Mann

Datti³

et al. 2004

Diabetes

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A large body of evidence now implicates increased leukocyte-endothelial cell adhesion as a key early event in the development of diabetic retinopathy. We recently reported that raised activity of the glycosylating enzyme core 2 ␤ 1,6-N-acetylglucosaminyltransferase (GlcNAc-T) through protein kinase C (PKC)␤2-dependent phosphorylation plays a fundamental role in increased leukocyteendothelial cell adhesion and capillary occlusion in retinopathy. In the present study, we demonstrate that following exposure to plasma from diabetic patients, the human promonocytic cell line U937 exhibits a significant elevation in core 2 GlcNAc-T activity and increased adherence to cultured retinal capillary endothelial cells. These effects of diabetic plasma on enzyme activity and cell adhesion, mediated by PKC␤2-dependent phosphorylation of the core 2 GlcNAc-T protein, were found to be triggered by increased plasma levels of tumor necrosis factor (TNF)-␣. Levels of enzyme activity in plasma-treated U937 cells were closely dependent on the severity of diabetic retinopathy, with the highest values observed upon treatment with plasma of patients affected by proliferative retinopathy. Furthermore, we noted much higher correlation, as compared with control subjects, between increased values of core 2 GlcNAc-T activity and cell adhesion properties. Based on the prominent role of TNF-␣ in the development of diabetic retinopathy, these observations further validate the significance of core 2 GlcNAc-T in the pathogenesis of capillary occlusion, thereby enhancing the therapeutic potential of specific enzyme inhibitors.

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Section: Methodsmentioning

confidence: 99%

Tumor Necrosis Factor-α in Diabetic Plasma Increases the Activity of Core 2 GlcNAc-T and Adherence of Human Leukocytes to Retinal Endothelial Cells

Ben-Mahmud

Mann

Datti³

et al. 2004

Diabetes

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show abstract

“…Culture of human myelocytic cell line (U937). This leukocytic cell line (35) was cultured in glucose-free RPMI medium (Sigma, Poole, UK) supplemented with 10% FCS, 2 mmol/l glutamine, 100 IU/ml penicillin, 100 g/ml streptomycin, and 5 mmol/l glucose. For experimentation, the cells were centrifuged, washed in PBS, and exposed to varying concentrations of D-glucose (5.8, 6.5,15, 25 mmol/l) and mannitol (15 mmol/l) in RPMI.…”

Section: Methodsmentioning

confidence: 99%

Protein Kinase C β2-Dependent Phosphorylation of Core 2 GlcNAc-T Promotes Leukocyte-Endothelial Cell Adhesion

et al. 2003

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Increased leukocyte-endothelial cell adhesion is a key early event in the development of retinopathy and atherogenesis in diabetic patients. We recently reported that raised activity of glycosylating enzyme [␤]1,6 acetylglucosaminyltransferase (core 2 GlcNAc-T) is responsible for increased leukocyte-endothelial cell adhesion and capillary occlusion in retinopathy. Here, we demonstrate that elevated glucose increases the activity of core 2 GlcNAc-T and adhesion of human leukocytes to retinal capillary endothelial cells, in a dose-dependent manner, through diabetes-activated serine/threonine protein kinase C ␤2 (PKC␤2)-dependent phosphorylation. This regulatory mechanism, involving phosphorylation of core 2 GlcNAc-T, is also present in polymorphonuclear leukocytes isolated from type 1 and type 2 diabetic patients. Inhibition of PKC␤2 activation with the specific inhibitor, LY379196, attenuated serine phosphorylation of core 2 GlcNAc-T and prevented increased leukocyte-endothelial cell adhesion. Raised activity of core 2 GlcNAc-T was associated with a threefold increase in O-linked glycosylation of P-selectin glycoprotein ligand-1 on the surface of leukocytes of diabetic patients compared with age-matched control subjects. PKC␤2-dependent phosphorylation of core 2 GlcNAc-T may thus represent a novel regulatory mechanism for activation of this key enzyme in mediating increased leukocyte-endothelial cell adhesion and capillary occlusion in diabetic retinopathy. Diabetes 52: 1519 -1527, 2003 D iabetic retinopathy, a leading cause of severe visual loss in type 1 and type 2 diabetic patients (1) is characterized in its early stage by areas of capillary nonperfusion and microvascular damage (2,3). As in atherogenesis (4), increased leukocyteendothelial cell adhesion is a key early event in the development of capillary occlusion in retinopathy (5-10). Leukocytes from diabetic patients are more adhesive to endothelial cells (11), and in experimental diabetes, their increased entrapment in retinal capillaries leads to areas of capillary nonperfusion and endothelial cell damage (12). Increased adhesion of leukocytes in diabetic patients may result from an increased expression of intracellular adhesion molecule (ICAM)-1 on endothelial cells and/or expression of integrins (CD11a, CD11b, and CD18b) on leukocytes (13-16).We recently reported that raised activity of the glycosylating enzyme [␤]1,6-acetylglucosaminyltransferase (core 2 GlcNAc-T) is responsible for increased leukocyte-endothelial cell adhesion and capillary occlusion in retinopathy (17). This Golgi enzyme plays a crucial role in the biosynthesis of O-linked glycans by converting core 1 (i.e., Gal (21), T-cell activation (22), inflammation (23), myocardial dysfunction (24,25), capillary morphogenesis (26), and myeloblastic leukemia (27). On the basis that O-linked sugars are also involved in cell-cell interactions (28), we proposed that their modification by raised activity of core 2 GlcNAc-T, together with glucose-induced expression of adhesion molecules on endoth...

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“…Ketosis is associated with OS. 3-Hydroxybutyrate and its pre-cursor, acetoacetate, have been shown to generate ROS [42][43][44], and lipids are peroxidised by ROS. These observations are consistent with the lAT patients being more susceptible to oxidative stress during surgery than the hAT patients, since they had higher levels of 3-hydroxybutyrate and acetoacetate, and lower levels of lipids.…”

Section: Resultsmentioning

confidence: 99%

Metabolic Profiling of Patients Undergoing Elective Aortic Aneurysm Repair Surgery: Correlation with Anaerobic Threshold

McRae

Howard

Homer-Vanniasinkam

et al. 2012

ISRN Vascular Medicine

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The anaerobic threshold (AT) measured by the cardiopulmonary exercise (CPX) test is becoming an established means of identifying patients at high risk of developing cardiac complications perioperatively. The aim of the present study was to investigate the relationship between AT and the plasma metabolic profile of patients undergoing aortic aneurysm repair surgery to see if an alternative or adjunct to the CPX test could be devised. Plasma was obtained from 15 male patients classified (through preoperative CPX tests) as having high (≥11.0 mL kg −1 min −1 ) or low (<11.0 mL kg −1 min −1 ) AT before and 1, 2, 24, 48, and 72 hours after elective open aortic aneurysm surgery. Samples were analysed using 1 H-NMR spectroscopy coupled with multivariate statistical analysis. Principal components analysis (PCA) and partial least squares discriminant analysis (PLS-DA) distinguished between low-and high-AT patients postoperatively, with high AT patients being more tightly clustered. High AT patients had higher plasma lipid and lower 3-hydroxybutyrate and acetoacetate levels than low AT patients post-operatively. Similar differences were identified preoperatively. 1 H-NMR metabolic profiling of plasma has identified molecules whose concentration correlates with AT scores. These may prove a useful biomarker in conjunction with AT in predicting response to major surgical procedures.

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Hyperketonemia Increases Tumor Necrosis Factor-α Secretion in Cultured U937 Monocytes and Type 1 Diabetic Patients and Is Apparently Mediated by Oxidative Stress and cAMP Deficiency

Cited by 106 publications

References 50 publications

Tumor Necrosis Factor-α in Diabetic Plasma Increases the Activity of Core 2 GlcNAc-T and Adherence of Human Leukocytes to Retinal Endothelial Cells

Tumor Necrosis Factor-α in Diabetic Plasma Increases the Activity of Core 2 GlcNAc-T and Adherence of Human Leukocytes to Retinal Endothelial Cells

Protein Kinase C β2-Dependent Phosphorylation of Core 2 GlcNAc-T Promotes Leukocyte-Endothelial Cell Adhesion

Metabolic Profiling of Patients Undergoing Elective Aortic Aneurysm Repair Surgery: Correlation with Anaerobic Threshold

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