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Advanced-glycation endproducts implication in the acceleration of diabetes-induced elastocalcinosis
14th IVBM Abstracts
B13.12 Advanced-glycation endproducts implication in the acceleration of diabetes-induced elastocalcinosis Céline Bouvet, Simon Moreau, Denis deBlois, Pierre Moreau Université de Montréal, Montréal, Canada In diabetes, elastocalcinosis is accelerated in distal arteries, and it is correlated with the duration and severity of the disease. We devised a model of elastocalcinosis in association with type 2 diabetes in order to study the mechanisms. Males Wistar rats received a high-fat diet during 2 months and then a low dose injection of streptozotocin (30 mg/kg i.p.) to induce type 2 diabetes (D). Elastocalcinosis was induced by 3 weeks of treatment with warfarin 15 mg/kg/d and vitamin K 15 mg/kg/d (WVK). WVK treatment was started 1 (D1W3) and 4 weeks (D4W3) after the injection of streptozotocin, and in controls (W3). Untreated rats were used as control (Ctrl). Pyridoxamine (100 mg/kg/d) was administered at the beginning of the WVK treatment (D4W3 + pyr). Other rats received ALT711, an AGEs breaker (10 mg/kg/d), for 4 weeks starting 3 weeks after the beginning of WVK treatment (D4W7 + ALT711). They were compared to diabetic rats treated with WVK for 7 weeks (D4W7). Three weeks of treatment with WVK alone did not increase the calcium amount in femoral arteries (W3: 0.36 ± 0.09 vs Ctrl: 0.8 ± 0.1 μg/mg of tissue). Femoral calcification was accelerated in the D4W3 group (3.6 ± 1.3 μg/mg, p< 0.001), but not in the D1W3 group. AGEs deposition on collagen of femoral artery also increased only in the D4W3 group (2.96 ± 0.79 vs W3: 0.76 ± 0.26 AU/mg collagen, p< 0.05). No significant change of the aortic calcium amount was observed in all groups. Femoral calcification was significantly prevented by pyridoxamine (D4W3 + pyr: 0.6 ± 0.1 vs D4W3: 3.6 ± 1.3 μg/ mg, p< 0.05) and with ALT711 (D4W7 + ALT711: 3.2 ± 0.7 vs D4W7: 10.5 ± 3.4 μg/mg, p< 0.001). We have established a model of accelerated elastocalcinosis in diabetes linked to its duration, severity and localized in distal arteries. This calcification was prevented with pyridoxamine and its progression was limited by ALT 711, suggesting that, in diabetes, accelerated elastocalcinosis is linked to AGEs formation. doi:10.1016/j.vph.2006.08.266
e95
isms underlying this damage remain undefined. We now demonstrate that hyperglycemia induces activation of sphingosine kinase (SphK) which represents a novel signaling pathway that mediates endothelial inflammation under ambient high glucose conditions. SphK activity was significantly increased in the aorta and heart of STZ-induced diabetic rats. Interestingly, this increase in SphK activity was prevented by insulin treatment that achieved euglycemia in the diabetic animals. Hyperglycemia-induced increase in SphK activity was also evident in endothelial cells that were chronically exposed to high glucose (22 mmol/L). Studies using a small interfering RNA (siRNA) strategy demonstrated that endogenous SphK1, but not SphK2, is the major isoenzyme that was activated by high glucose. In addition, an increase in SphK1 phosphorylation was detected in a PKC- and ERK1/2-dependent manner, which accounts for the high glucose-induced increases in SphK activity. Importantly, inhibition of SphK1 by either a chemical inhibitor (N′N′-dimethylsphingosine) or expression of a dominant-negative mutant of SphK1 (SphKG82D), or SphK1specific siRNA, strongly protected endothelial cells against high glucose-induced inflammatory phenotypes, as characterized by an attenuation in the expression of pro-inflammatory adhesion molecules, adhesion of leukocytes to endothelial cells and NF-kB activation. Thus, interventions that target the SphK signaling pathway may have the potential to prevent vascular lesions under hyperglycemic conditions. doi:10.1016/j.vph.2006.08.267
B13.14 The effect of maternal hypercholesterolemia on vascular differentiation and fetal plasma cholesterol levels Fanneke E. Alkemade1, Marco C. DeRuiter1, Ko Willems van Dijk2, Conny J. VanMunsteren1, Louis M. Havekes3, Adriana C. Gittenberger-de Groot1 1
Dept. Anatomy and Embryology, Leiden University Medical Center, Leiden, The Netherlands 2 Dept. Human Genetics, Leiden University Medical Center, Leiden, The Netherlands 3 TNO-Quality of life, Gaubius Laboratory, Leiden, The Netherlands
B13.13 Role of sphingosine kinase-1 in high-glucose mediated endothelial inflammation Pu Xia Signal Transduction Laboratory, Hanson Institute, Adelaide, Australia Vascular endothelial cells are key targets for hyperglycemic damage that facilitates vascular inflammation and the vasculopathy associated with diabetes mellitus. However, the mechan-
Intrauterine exposure of the human fetus to high levels of cholesterol appears to lead to increased formation of fatty streaks in the fetal aorta and promotes development of atherosclerosis in adult life. However, little is known on the contribution of genetic background of the fetus on intrinsic lipid metabolism and vascular remodeling in combination with maternal normo- or hypercholesterolemia (M-NC, M-HC respectively). We hypothesize that M-HC results in changes in fetal plasma lipid levels leading to altered vascular remodeling in the embryo and increased susceptibility to vascular disease in adult offspring. C57Bl/6J wild type, LDL
B13.12 Advanced-glycation endproducts implication in the acceleration of diabetes-induced elastocalcinosis Céline Bouvet, Simon Moreau, Denis deBlois, Pierre Moreau Université de Montréal, Montréal, Canada In diabetes, elastocalcinosis is accelerated in distal arteries, and it is correlated with the duration and severity of the disease. We devised a model of elastocalcinosis in association with type 2 diabetes in order to study the mechanisms. Males Wistar rats received a high-fat diet during 2 months and then a low dose injection of streptozotocin (30 mg/kg i.p.) to induce type 2 diabetes (D). Elastocalcinosis was induced by 3 weeks of treatment with warfarin 15 mg/kg/d and vitamin K 15 mg/kg/d (WVK). WVK treatment was started 1 (D1W3) and 4 weeks (D4W3) after the injection of streptozotocin, and in controls (W3). Untreated rats were used as control (Ctrl). Pyridoxamine (100 mg/kg/d) was administered at the beginning of the WVK treatment (D4W3 + pyr). Other rats received ALT711, an AGEs breaker (10 mg/kg/d), for 4 weeks starting 3 weeks after the beginning of WVK treatment (D4W7 + ALT711). They were compared to diabetic rats treated with WVK for 7 weeks (D4W7). Three weeks of treatment with WVK alone did not increase the calcium amount in femoral arteries (W3: 0.36 ± 0.09 vs Ctrl: 0.8 ± 0.1 μg/mg of tissue). Femoral calcification was accelerated in the D4W3 group (3.6 ± 1.3 μg/mg, p< 0.001), but not in the D1W3 group. AGEs deposition on collagen of femoral artery also increased only in the D4W3 group (2.96 ± 0.79 vs W3: 0.76 ± 0.26 AU/mg collagen, p< 0.05). No significant change of the aortic calcium amount was observed in all groups. Femoral calcification was significantly prevented by pyridoxamine (D4W3 + pyr: 0.6 ± 0.1 vs D4W3: 3.6 ± 1.3 μg/ mg, p< 0.05) and with ALT711 (D4W7 + ALT711: 3.2 ± 0.7 vs D4W7: 10.5 ± 3.4 μg/mg, p< 0.001). We have established a model of accelerated elastocalcinosis in diabetes linked to its duration, severity and localized in distal arteries. This calcification was prevented with pyridoxamine and its progression was limited by ALT 711, suggesting that, in diabetes, accelerated elastocalcinosis is linked to AGEs formation. doi:10.1016/j.vph.2006.08.266
e95
isms underlying this damage remain undefined. We now demonstrate that hyperglycemia induces activation of sphingosine kinase (SphK) which represents a novel signaling pathway that mediates endothelial inflammation under ambient high glucose conditions. SphK activity was significantly increased in the aorta and heart of STZ-induced diabetic rats. Interestingly, this increase in SphK activity was prevented by insulin treatment that achieved euglycemia in the diabetic animals. Hyperglycemia-induced increase in SphK activity was also evident in endothelial cells that were chronically exposed to high glucose (22 mmol/L). Studies using a small interfering RNA (siRNA) strategy demonstrated that endogenous SphK1, but not SphK2, is the major isoenzyme that was activated by high glucose. In addition, an increase in SphK1 phosphorylation was detected in a PKC- and ERK1/2-dependent manner, which accounts for the high glucose-induced increases in SphK activity. Importantly, inhibition of SphK1 by either a chemical inhibitor (N′N′-dimethylsphingosine) or expression of a dominant-negative mutant of SphK1 (SphKG82D), or SphK1specific siRNA, strongly protected endothelial cells against high glucose-induced inflammatory phenotypes, as characterized by an attenuation in the expression of pro-inflammatory adhesion molecules, adhesion of leukocytes to endothelial cells and NF-kB activation. Thus, interventions that target the SphK signaling pathway may have the potential to prevent vascular lesions under hyperglycemic conditions. doi:10.1016/j.vph.2006.08.267
B13.14 The effect of maternal hypercholesterolemia on vascular differentiation and fetal plasma cholesterol levels Fanneke E. Alkemade1, Marco C. DeRuiter1, Ko Willems van Dijk2, Conny J. VanMunsteren1, Louis M. Havekes3, Adriana C. Gittenberger-de Groot1 1
Dept. Anatomy and Embryology, Leiden University Medical Center, Leiden, The Netherlands 2 Dept. Human Genetics, Leiden University Medical Center, Leiden, The Netherlands 3 TNO-Quality of life, Gaubius Laboratory, Leiden, The Netherlands
B13.13 Role of sphingosine kinase-1 in high-glucose mediated endothelial inflammation Pu Xia Signal Transduction Laboratory, Hanson Institute, Adelaide, Australia Vascular endothelial cells are key targets for hyperglycemic damage that facilitates vascular inflammation and the vasculopathy associated with diabetes mellitus. However, the mechan-
Intrauterine exposure of the human fetus to high levels of cholesterol appears to lead to increased formation of fatty streaks in the fetal aorta and promotes development of atherosclerosis in adult life. However, little is known on the contribution of genetic background of the fetus on intrinsic lipid metabolism and vascular remodeling in combination with maternal normo- or hypercholesterolemia (M-NC, M-HC respectively). We hypothesize that M-HC results in changes in fetal plasma lipid levels leading to altered vascular remodeling in the embryo and increased susceptibility to vascular disease in adult offspring. C57Bl/6J wild type, LDL