Development Of Atherosclerosis In Diabetes Research Articles

Crocin Protects Human Umbilical Vein Endothelial Cells from High Glucose-Induced Injury Via Inhibiting the Endoplasmic Reticulum Stress Response.

Endothelial dysfunction plays a key role in diabetic atherosclerosis. High glucose (HG) is considered a stimulator in the development of diabetic atherosclerosis. The endoplasmic reticulum (ER) stress response is involved in HG-induced vascular injury. Crocin has antioxidative and antiapoptotic properties. The current study was to evaluate whether crocin can protect human umbilical vein endothelial cells (HUVECs) from HG-induced injury and explored the associated mechanism. HUVECs were treated with 33 mmol/L glucose as the HG condition. The endothelial protective effects of crocin were evaluated by comparison with the control groups. The exposure of HUVECs to HG for 24 h remarkably induced the ER stress response and a sequence of injuries, as demonstrated an increase in the apoptotic cell number, the reactive oxygen species level and inflammatory cytokine generation, as well as a decline in vascular endothelial growth factor A expression. These changes were markedly alleviated by pretreating the HUVECs with either crocin or 4-phenylbutyrate (ER stress inhibitor) before exposure to HG. Crocin exerted antioxidative, antiapoptotic, anti-inflammatory and proangiogenic effects in the HG-induced HUVEC injury model, which were probably mediated by a favorable modification of ER stress that requires further investigation.

Humanin prevents high glucose-induced monocyte adhesion to endothelial cells by targeting KLF2

Endothelial dysfunction and vascular complications induced by hyperglycemia play an important role in the pathological development of atherosclerosis in diabetes. Humanin, a 24-amino acid mitochondria-derived polypeptide, has displayed its cytoprotective effects in diverse cell types and tissues. In the current study, we aimed to characterize the effects of humanin on high glucose-induced endothelial dysfunction. Firstly, we found that humanin treatment induced the expression of Krüppel-like factor 2 (KLF2), an essential transcriptional regulator of endothelial function, at the transcriptional level in human umbilical vein endothelial cells (HUVECs). Additionally, our results indicate that humanin treatment regulated the expression of KLF2 target genes such as endothelial nitric oxide synthase (eNOS) and endothelin-1 (ET-1). Evidence demonstrated that the effects of humanin on KLF2 expression was mediated by the phosphorylation of extracellular signal regulated kinase 5 (ERK5). Furthermore, humanin restored high glucose-induced reduction of KLF2 expression. We also showed that humanin significantly reduced the expression of vascular cell adhesion molecule 1 (VCAM-1) and E-selectin. Notably, humanin treatment markedly prevented high glucose-induced attachment of the monocyte THP-1 cells to HUVECs. However, knockdown of KLF2 abolished these effects. Lastly, we report that humanin treatment inhibited high glucose-induced secretion of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). These findings suggest that humanin may have therapeutic potential for the treatment of hyperglycemia-associated endothelial dysfunction.

Abstract 550: Alteration of Glycolysis Metabolite Levels and Impaired Hypoxic Response in Diabetic Atherosclerosis

Objective: Diabetes mellitus accelerates atherosclerosis that causes most cardiovascular events. Several metabolic pathways are considered to contribute to the development of atherosclerosis, but comprehensive metabolic alterations to atherosclerotic arterial cells remain unknown. The present study investigated metabolic status and their relationship to vascular histopathological changes in the atherosclerotic arteries of rabbits with alloxan-induced diabetes. Approach and Results: Diabetic atherosclerosis was induced in rabbits ilio-femoral arteries by injecting alloxan (100 mg/kg), injuring the arteries using a balloon, and feeding with a 0.5% cholesterol diet. Plaque burden, macrophage content, and hypoxic areas were more prevalent in arteries with diabetic, than non-diabetic atherosclerosis. Metabolomic analyses highlighted 12 metabolites that were significantly altered between diabetic and non-diabetic atherosclerosis. A half of them were associated with glycolysis metabolites, and their levels were decreased in diabetic atherosclerosis. The uptake of glucose evaluated as 18 F-fluorodeoxyglucose in atherosclerotic lesions increased according to increased macrophage content or hypoxic areas in non-diabetic, but not diabetic rabbits. Despite profound hypoxic areas, the nuclear localization of hypoxia-inducible factor-1α decreased and the number of apoptotic cells increased in diabetic atherosclerotic lesions. Conclusions: Altered glycolysis metabolism and an impaired response to hypoxia in atherosclerotic lesions under conditions of insulin-dependent diabetes might be involved in the development of diabetic atherosclerosis.

Altered glucose metabolism and hypoxic response in alloxan-induced diabetic atherosclerosis in rabbits.

Diabetes mellitus accelerates atherosclerosis that causes most cardiovascular events. Several metabolic pathways are considered to contribute to the development of atherosclerosis, but comprehensive metabolic alterations to atherosclerotic arterial cells remain unknown. The present study investigated metabolic changes and their relationship to vascular histopathological changes in the atherosclerotic arteries of rabbits with alloxan-induced diabetes. Diabetic atherosclerosis was induced in rabbit ilio-femoral arteries by injecting alloxan (100 mg/kg), injuring the arteries using a balloon, and feeding with a 0.5% cholesterol diet. We histologically assessed the atherosclerotic lesion development, cellular content, pimonidazole positive-hypoxic area, the nuclear localization of hypoxia-inducible factor-1α, and apoptosis. We evaluated comprehensive arterial metabolism by performing metabolomic analyses using capillary electrophoresis-time of flight mass spectrometry. We evaluated glucose uptake and its relationship to vascular hypoxia using 18F-fluorodeoxyglucose and pimonidazole. Plaque burden, macrophage content, and hypoxic areas were more prevalent in arteries with diabetic, than non-diabetic atherosclerosis. Metabolomic analyses highlighted 12 metabolites that were significantly altered between diabetic and non-diabetic atherosclerosis. A half of them were associated with glycolysis metabolites, and their levels were decreased in diabetic atherosclerosis. The uptake of glucose evaluated as 18F-fluorodeoxyglucose in atherosclerotic lesions increased according to increased macrophage content or hypoxic areas in non-diabetic, but not diabetic rabbits. Despite profound hypoxic areas, the nuclear localization of hypoxia-inducible factor-1α decreased and the number of apoptotic cells increased in diabetic atherosclerotic lesions. Altered glycolysis metabolism and an impaired response to hypoxia in atherosclerotic lesions under conditions of insulin-dependent diabetes might be involved in the development of diabetic atherosclerosis.

Anti-collagen type iv igg antibodies and risk for development of atherosclerosis in diabetics with essential hypertension

Anti-collagen type iv igg antibodies and risk for development of atherosclerosis in diabetics with essential hypertension

Modified lipoproteins as biomarkers of cardiovascular risk in diabetes mellitus

Prevention of high incidence of cardiovascular disease in diabetes is one of the challenges of endocrinology. Validation of new biomarkers that may contribute to a better assessment of cardiovascular risk and help implement treatment strategies is one of the promising approaches in research on prevention and reduction of cardiovascular risk. Modification of low density lipoprotein (LDL) is a key element in development of atherosclerotic lesions. Several pathophysiological characteristics of diabetes are crucial for the LDL of these patients to have higher modification rates as compared to the healthy population. Diabetic dyslipidemia, hyperglycemia, and oxidative stress synergistically promote the occurrence of lipoperoxidation, glycosylation and glycoxidation processes, which will generate modified lipoproteins that stimulate development of atherosclerosis. This article reviews the role of different types of modified LDL in development of atherosclerosis in diabetes, as well as the possibility of using its quantification in cardiovascular risk prediction.

PKCβ Promotes Vascular Inflammation and Acceleration of Atherosclerosis in Diabetic ApoE Null Mice

Subjects with diabetes mellitus are at high risk for developing atherosclerosis through a variety of mechanisms. Because the metabolism of glucose results in production of activators of protein kinase C (PKC)β, it was logical to investigate the role of PKCβ in modulation of atherosclerosis in diabetes mellitus. ApoE(-/-) and PKCβ(-/-)/ApoE(-/-) mice were rendered diabetic with streptozotocin. Quantification of atherosclerosis, gene expression profiling, or analysis of signaling molecules was performed on aortic sinus or aortas from diabetic mice. Diabetes mellitus-accelerated atherosclerosis increased the level of phosphorylated extracellular signal-regulated kinase 1/2 and Jun-N-terminus kinase mitogen-activated protein kinases and augmented vascular expression of inflammatory mediators, as well as increased monocyte/macrophage infiltration and CD11c(+) cells accumulation in diabetic ApoE(-/-) mice, processes that were diminished in diabetic PKCβ(-/-)/ApoE(-/-) mice. In addition, pharmacological inhibition of PKCβ reduced atherosclerotic lesion size in diabetic ApoE(-/-) mice. In vitro, the inhibitors of PKCβ and extracellular signal-regulated kinase 1/2, as well as small interfering RNA to Egr-1, significantly decreased high-glucose-induced expression of CD11c (integrin, alpha X 9 complement component 3 receptor 4 subunit]), chemokine (C-C motif) ligand 2, and interleukin-1β in U937 macrophages. These data link enhanced activation of PKCβ to accelerated diabetic atherosclerosis via a mechanism that includes modulation of gene transcription and signal transduction in the vascular wall, processes that contribute to acceleration of vascular inflammation and atherosclerosis in diabetes mellitus. Our results uncover a novel role for PKCβ in modulating CD11c expression and inflammatory response of macrophages in the development of diabetic atherosclerosis. These findings support PKCβ activation as a potential therapeutic target for prevention and treatment of diabetic atherosclerosis.

Lipoproteínas modificadas como marcadores de riesgo cardiovascular en la diabetes mellitus

Prevention of high incidence of cardiovascular disease in diabetes is one of the challenges of endocrinology. Validation of new biomarkers that may contribute to a better assessment of cardiovascular risk and help implement treatment strategies is one of the promising approaches in research on prevention and reduction of cardiovascular risk. Modification of low density lipoprotein (LDL) is a key element in development of atherosclerotic lesions. Several pathophysiological characteristics of diabetes are crucial for the LDL of these patients to have higher modification rates as compared to the healthy population. Diabetic dyslipidemia, hyperglycemia, and oxidative stress synergistically promote the occurrence of lipoperoxidation, glycosylation and glycoxidation processes, which will generate modified lipoproteins that stimulate development of atherosclerosis. This article reviews the role of different types of modified LDL in development of atherosclerosis in diabetes, as well as the possibility of using its quantification in cardiovascular risk prediction.

Manganese Supplementation Reduces High Glucose-induced Monocyte Adhesion to Endothelial Cells and Endothelial Dysfunction in Zucker Diabetic Fatty Rats

Endothelial dysfunction is a hallmark of increased vascular inflammation, dyslipidemia, and the development of atherosclerosis in diabetes. Previous studies have reported lower levels of Mn(2+) in the plasma and lymphocytes of diabetic patients and in the heart and aortic tissue of patients with atherosclerosis. This study examines the hypothesis that Mn(2+) supplementation can reduce the markers/risk factors of endothelial dysfunction in type 2 diabetes. Human umbilical vein endothelial cells (HUVECs) were cultured with or without Mn(2+) supplementation and then exposed to high glucose (HG, 25 mm) to mimic diabetic conditions. Mn(2+) supplementation caused a reduction in monocyte adhesion to HUVECs treated with HG or MCP-1. Mn(2+) also inhibited ROS levels, MCP-1 secretion, and ICAM-1 up-regulation in HUVECs treated with HG. Silencing studies using siRNA against MnSOD showed that similar results were observed in MnSOD knockdown HUVECs following Mn(2+) supplementation, suggesting that the effect of manganese on monocyte adhesion to endothelial cells is mediated by ROS and ICAM-1, but not MnSOD. To validate the relevance of our findings in vivo, Zucker diabetic fatty rats were gavaged daily with water (placebo) or MnCl2 (16 mg/kg of body weight) for 7 weeks. When compared with placebo, Mn(2+)-supplemented rats showed lower blood levels of ICAM-1 (17%, p < 0.04), cholesterol (25%, p < 0.05), and MCP-1 (28%, p = 0.25). These in vitro and in vivo studies demonstrate that Mn(2+) supplementation can down-regulate ICAM-1 expression and ROS independently of MnSOD, leading to a decrease in monocyte adhesion to endothelial cells, and therefore can lower the risk of endothelial dysfunction in diabetes.

Role of KCa3.1 Channels in Proliferation and Migration of Vascular Smooth Muscle Cells by Diabetic Rat Serum

Proliferation and migration of vascular smooth muscle cells (VSMCs) are important events in the development of diabetic atherosclerosis. Previous studies have suggested that K(Ca)3.1 channels participate in atherosclerosis and coronary artery restenosis. In the present study, we attempted to clarify the roles of K(Ca)3.1 channels in the proliferation and migration of VSMCs using experimental type-2 diabetes rat serum and aortic smooth muscle cells (SMC) prepared from non-diabetic rats. mRNA and protein levels and current density of K(Ca)3.1 channels were greatly enhanced in cultured VSMCs treated with diabetic serum. In addition, diabetic serum promoted cell proliferation and migration in cultured VSMCs, and the effects were fully reversed in the cells treated with the K(Ca)3.1 channels blocker TRAM-34. In conclusion, serum from diabetic rats increases the expression of K(Ca)3.1 channels and promotes proliferation and migration of VSMCs to possibly participate in vascular remodeling in diabetes.

Doinseunggitang Ameliorates Endothelial Dysfunction in Diabetic Atherosclerosis

Atherosclerosis, a chronic and progressive disease characterized by vascular inflammation, is a leading cause of death in diabetes patients. Doinseunggitang (DYSGT), traditional prescription, has been used for promoting blood circulation to remove blood stasis. The aim of this study was to investigate the beneficial effects of DYSGT on endothelial dysfunction in diabetic atherosclerosis animal model. Apolipoprotein E knockout (ApoE KO) mice fed on a Western diet were treated with DYSGT (200 mg/kg/day). DYSGT significantly lowered blood glucose level and glucose tolerance as well as systolic blood pressure. Metabolic parameter showed that DYSGT markedly decreased triglyceride and LDL-cholesterol levels. In the thoracic aorta, the impairment of vasorelaxation response to acetylcholine and atherosclerotic lesion was attenuated by DYSGT. Furthermore, DYSGT restored the reduction of endothelial nitric oxide synthase (eNOS) expression, leading to the inhibition of intracellular adhesion molecule-1 (ICAM-1) and endothelin-1 (ET-1) expression. In conclusion, DYSGT improved the development of diabetic atherosclerosis via attenuation of the endothelial dysfunction, possibly by inhibiting ET-1, cell adhesion molecules, and lesion formation. Therefore, these results suggest that Korean traditional prescription Doinseunggitang may be useful in the treatment and prevention of diabetic vascular complications.

Serum glycated albumin predicts the progression of carotid arterial atherosclerosis

IntroductionWe investigated the association between the ratio of serum glycated albumin (GA) levels to hyperglycemic levels (GA/A1c ratio) and the progression of carotid artery atherosclerosis. MethodsFor this retrospective longitudinal study we recruited patients who had undergone carotid IMT measurement twice and been tested consecutively for both A1c and GA levels every 3 or 6 months. The subjects were classified into two groups based on non-progression (group I) and progression (group II) of carotid IMT. Mean values of A1c and GA and the GA/A1c ratio were compared between groups. ResultsOf the 218 subjects (122 men and 96 women), group II (n=77) showed significantly higher baseline systolic BP, eGFR, GA, GA/A1c ratio, and progression of carotid IMT (Δ IMT) than group I (n = 141). The mean A1c level tended to be higher in group II than in group I (p = 0.054). By Spearman's correlation test, baseline diastolic BP, total cholesterol, triglyceride, GA, and GA/A1c were significantly associated with Δ IMT in group II but not in group I. In multivariate regression analysis, serum level of GA and GA/HbA1c ratio predicted progression of IMT after adjustment for other risk factors in both models applied. ConclusionWe suggest that glycated albumin is not only a useful glycemic index but also might be an atherogenic protein in the development of diabetic atherosclerosis.

Reduced alpha-lipoic acid synthase gene expression exacerbates atherosclerosis in diabetic apolipoprotein E-deficient mice

ObjectivesTo study the effects of reduced lipoic acid gene expression on diabetic atherosclerosis in apolipoprotein E null mice (Apoe−/−). Methods and resultsHeterozygous lipoic acid synthase gene knockout mice (Lias+/−) crossed with Apoe−/− mice were used to evaluate the diabetic effect induced by streptozotocin on atherosclerosis in the aortic sinus of the heart. While diabetes markedly increased atherosclerotic plaque size in Apoe−/− mice, a small but significant effect of reduced expression of lipoic acid gene was observed in diabetic Lias+/−Apoe−/− mice. In the aortic lesion area, the Lias+/−Apoe−/− mice exhibited significantly increased macrophage accumulation and cellular apoptosis than diabetic Lias+/+Apoe−/− littermates. Plasma glucose, cholesterol, and interleukin-6 were also higher. These abnormalities were accompanied with increased oxidative stress including a decreased ratio of reduced glutathione/oxidized glutathione in erythrocytes, increased systemic lipid peroxidation, and increased Gpx1 and MCP1 gene expression in the aorta. ConclusionsDecreased endogenous lipoic acid gene expression plays a role in development of diabetic atherosclerosis. These findings extend our understanding of the role of antioxidant in diabetic atherosclerosis.

Manganese downregulates ICAM‐1 expression in endothelial cells treated with high glucose

Diabetes is associated with low levels of manganese (Mn2+), an important component of many enzyme systems. Previous studies in our laboratory have shown that Zucker diabetic fatty rats (ZDF) supplemented with Mn2+ lower cholesterol, triglycerides, MCP‐1, ICAM‐1 and higher adiponectin levels in blood. This study examined the potential mechanisms by which Mn2+ supplementation decreases blood cholesterol and triglycerides and atherosclerosis associated with diabetes. Human umbilical vein endothelial cells (HUVECs) were treated with different concentrations of Mn2+ (0, 5, 10 and 20μM) for 24 hours, then exposed to high glucose (25mM) or MCP‐1 (250pg/mL) for another 24 hrs. ICAM‐1 expression was determined by Western blotting. Our results demonstrate that HG increases ICAM‐1 expression by two fold compared with controls, and that pre‐treatment with 5μM Mn2+ decreased ICAM‐1 expression back to control levels. Similar experiments with 3T3‐L1 adipocytes showed that pre‐treatment with 10μM Mn2+ inhibited HG‐induced secretion of MCP‐1 levels to control levels. ICAM‐1 and MCP‐1 are key players in the development of atherosclerosis and CVD in diabetes. This study suggests that Mn2+ supplementation inhibits MCP‐1 secretion and ICAM‐1 expression, which in turn may lower circulating triglycerides and cholesterol and risk of development of atherosclerosis in diabetes. Supported by NIDDK (RO1 DK072433), Office of Dietary Supplements and Malcolm Feist Chair in Diabetes.

Regulation and Maintenance of Vascular Tone and Patency in Cardiovascular Health and Disease

Despite numerous advances in health care practices, cardiovascular disease still remains the leading cause of morbidity and mortality worldwide. Perhaps the most important consequence of cardiovascular disease is the interruption of blood flow to organs such as the heart and brain, resulting in the clinical presentation of a heart attack or stroke. As such, the regulation of vascular tone and the maintenance of vascular patency are vital for the preservation of cardiovascular health. Central to this process is the vascular endothelium. The endothelium is vital for the regulation of vascular tone and the maintenance of vascular homeostasis, as it releases factors such as nitric oxide, hydrogen sulfide, endothelial-dependent hyperpolarizing factor, and prostacyclin that induce vasodilatation and keep the vasculature free of obstructions [1]. Therefore, it should be of no surprise that a number of the risk factors for the development of cardiovascular disease, such as hypertension, hypercholesterolemia, diabetes, smoking, ageing, and atherosclerosis, correlate with an impaired endothelium [2]. This impairment, termed endothelial dysfunction, is characterized by the reduction in the bioavailability of vasodilators, particularly nitric oxide, and/or an increase in endothelium-derived contracting factors [3]. The resulting imbalance leads to an impairment of endothelium-dependent vasodilation, as well as a compromised state of endothelial activation characterized by proinflammatory, proliferative, and procoagulatory conditions that favor all stages of atherogenesis [4]. Therefore, it is critically important to develop and implement therapeutic strategies that will combat endothelial dysfunction in an effort to reduce the mortality and morbidity associated with cardiovascular diseases. However, before therapeutic strategies can be implemented it is important to have a clear understanding of the pathological mechanisms that lead to the endothelial dysfunction in the first place. This special issue of highlights the latest findings related to the role of endothelial dysfunction in cardiovascular disease and comprises five review articles and one original report. The first three articles share the common theme of endothelial dysfunction in diabetes. Each paper offers unique insights into the mechanisms underlying diabetes-induced changes in endothelial biology and highlights specific pathways that could be novel therapeutic targets. The review article in this series by S. D. Funk et al. discusses the mechanisms that contribute to the development of atherosclerosis in diabetics. This paper highlights the central role of hyperglycemia in promoting endothelial dysfunction and discusses how cellular and animal studies have translated to clinical development of therapeutics targeting endothelial dysfunction in diabetes. The next paper by A. Sharma et al. highlights the importance of alterations in endothelium-derived nitric oxide (EDNO) production in the pathogenesis of vascular complications in both type 1 and type 2 diabetes. The interrelationship between reactive oxygen species (ROS) and EDNO is described, with emphasis on the cellular and molecular mechanisms that give rise to altered NO bioavailability in diabetes. In their paper, G. K. Kolluru et al. emphasize the importance of angiogenesis in diabetes and chronicle studies that have yielded mechanistic insights into the development of endothelial dysfunction in diabetes. This comprehensive paper, entitled “Endothelial dysfunction and diabetes: effects on angiogenesis, vascular remodeling, and wound healing,” discusses how ROS and deficiencies in NO bioavailability contribute to altered angiogenesis in diabetes. Therapeutic management of angiogenesis in diabetes is also discussed. In another review article in this series, M. Murakami provides a comprehensive overview of the mechanisms contributing to the active maintenance of the vasculature. The role of growth factors and cytokines in mediating endothelial and mural cell maintenance is described, with an analysis of how genetic alterations in these pathways give rise to blood vessel abnormalities and susceptibility to vascular disease. The molecular and cellular mechanisms leading to restenosis and the potential for new therapeutics targeting vascular smooth muscle cell (VSMC) proliferation are the topic of a review article in this series. L. Denes et al. highlight the importance of VSMC phenotype switching and proliferation in vascular disease and discuss the clinical diagnosis and management of restenosis. The original report by I. Liesmaa et al. is entitled “Bradykinin type-2 receptor expression correlates with age and is subjected to transcriptional regulation.” This study demonstrates that bradykinin type-2 receptor (BK-2R) mRNA is positively correlated with age, but is significantly reduced in human patients with idiopathic dilated cardiomyopathy (IDC) compared with healthy individuals. The study further examines the relationship between polymorphisms in the BK-2R promoter and the presence of IDC and coronary heart disease.

Increased Inflammation in Atherosclerotic Lesions of DiabeticAkita-LDLr−/−Mice Compared to NondiabeticLDLr−/−Mice

Background. Diabetes is associated with increased cardiovascular disease, but the underlying cellular and molecular mechanisms are poorly understood. One proposed mechanism is that diabetes aggravates atherosclerosis by enhancing plaque inflammation. The Akita mouse has recently been adopted as a relevant model for microvascular complications of diabetes. Here we investigate the development of atherosclerosis and inflammation in vessels of Akita mice on LDLr −/− background. Methods and Results. Akita-LDLr −/− and LDLr −/− mice were fed high-fat diet from 6 to 24 weeks of age. Blood glucose levels were higher in both male and female Akita-LDLr −/− mice (137% and 70%, resp.). Male Akita-LDLr −/− mice had markedly increased plasma cholesterol and triglyceride levels, a three-fold increase in atherosclerosis, and enhanced accumulation of macrophages and T-cells in plaques. In contrast, female Akita-LDLr −/− mice demonstrated a modest 29% increase in plasma cholesterol and no significant increase in triglycerides, atherosclerosis, or inflammatory cells in lesions. Male Akita-LDLr −/− mice had increased levels of plasma IL-1β compared to nondiabetic mice, whereas no such difference was seen between female diabetic and nondiabetic mice. Conclusion. Akita-LDLr −/− mice display considerable gender differences in the development of diabetic atherosclerosis. In addition, the increased atherosclerosis in male Akita-LDLr −/− mice is associated with an increase in inflammatory cells in lesions.

Fibrin(ogen) may be an important target for methylglyoxal-derived AGE modification in elastic arteries of humans

Diabetes is associated with increased risk of cardiovascular disease. Advanced glycation end-products (AGEs) are considered to be a major pathogenic factor for diabetic vascular complications. The levels of AGEs are increased in diabetic patients. We have studied the presence of the major AGE methylglyoxal (MGO)-derived hydroimidazolone in human aorta and carotid arteries, using immunohistochemistry (IHC), western blotting and mass spectrometry. By IHC, MGO-derived modifications were detected mainly associated with cells in intimal thickenings and cells in microvessels in adventitia. In type V lesions MGO-derived AGE was also present, extracellular in the necrotic core and in cells at the border of the core. The highest degree of modification was probably associated with cell nuclei. By western blotting and mass spectrometry fibrin(ogen), the cytoskeleton-associated protein moesin and the nuclear proteins lamin A and C were identified as putative main targets for MGO-derived modification. LC-MS/MS studies of fibrin(ogen) modified in vitro with low concentrations of MGO identified the sites that were most prone to modification. These results indicate that AGE modifications occur preferentially on specific proteins. The modification of these proteins may play a role in vascular dysfunction and development of atherosclerosis in diabetes.

Effects of miglitol in platelet-derived microparticle, adiponectin, and selectin level in patients with type 2 diabetes mellitus

Background:Platelet-derived microparticles (PDMP), selectins, and adiponectin play an important role in the development of atherosclerosis in diabetes. Miglitol has been shown to have a beneficial effect on postprandial hyperglycemia in diabetic patients. However, its influence on platelet activation markers (PDMP and soluble CD40 ligand [sCD40L]), selectins, and adiponectin in these patients is poorly understood.Aim:We investigated the effect of miglitol on circulating levels of PDMP, sCD40L, selectins, and adiponectin in patients with type 2 diabetes.Methods:Miglitol (150 mg/day) was administered for 4 months. Levels of PDMP, sCD40L, soluble P-selectin (sP-selectin), soluble E-selectin (sE-selectin), soluble L-selectin (sL-selectin), and adiponectin were measured by enzyme-linked immunosorbent assay at baseline, and after 1 and 4 months of treatment.Results:The levels of PDMP, sCD40L, sP-selectin, sE-selectin, and sL-selectin were higher in diabetic patients than in hypertensive patients, while there were no significant differences between hypertensive and hyperlipidemic patients. Before miglitol treatment, the adiponectin level of diabetic patients was lower than that of hypertensive patients. Miglitol therapy significantly decreased the plasma PDMP and sCD40L levels relative to baseline. Miglitol also caused a significant decrease of sP-selectin, sE-selectin, and sL-selectin. On the other hand, miglitol therapy led to a significant increase in adiponectin after 4 months of administration compared with baseline. Furthermore, the reduction of platelet activation markers and selectins during miglitol therapy was significantly greater in the responder (adiponectin-improved) group than the nonresponder group of diabetic patients.Conclusion:Miglitol has an adiponectin-dependent anti-atherothrombotic effect that may be beneficial for primary prevention of atherothrombosis in patients with type 2 diabetes.

Roles of SIRT1 in High Glucose-induced Endothelial Impairment: Association with Diabetic Atherosclerosis

Background and Aims We undertook this study to investigate the roles of SIRT1 in high glucose-induced endothelial impairment and their association with diabetic atherosclerosis. Methods Otsuka Long-Evans Tokushima Fatty (OLETF) rats and nondiabetic rats of the same genetic background were included. Real-time PCR was used to detect SIRT1 mRNA expression in abdominal aorta at week 42. To further investigate the roles of SIRT1 on the function of endothelial cells in high glucose, human endothelial cells were treated with SIRT1 activator resveratrol for 24 h before being cultured in high glucose medium for 48 h. Results Along with the early manifestation of atherosclerosis, SIRT1 mRNA level in OLETF group was significantly lower than that in control group ( p <0.05). Compared with control cells, high glucose decreased nitric oxide (NO) secretion, but resveratrol treatment increased the expression of SIRT1 and the secretion of NO. After interfering with the expression of SIRT1 using SIRT1 siRNA, the effects of resveratrol on NO secretion were impaired. SIRT1 also counteracted the other pro-atherosclerotic effects of high glucose including the upregulating roles of high glucose on the expression of E-selectin mRNA and the downregulating roles of high glucose on the expression of endothelial nitric oxide synthase. Conclusions Decreased expression of SIRT1 in artery may be involved in the initiation and development of diabetic atherosclerosis. Increasing SIRT1 expression may hold great promise in the prevention and therapy of atherosclerosis in diabetic patients.

Intermittent high glucose enhances proliferation of vascular smooth muscle cells by upregulating osteopontin

Objective Hyperglycemia induces vascular smooth muscle cells (VSMCs) proliferation and may thus contribute to the formation of atherosclerotic lesions. Glucose fluctuations are strong predictor of diabetic vascular complications. We investigate the effects of exposure to constant and intermittent high glucose concentrations on the proliferation and matrix metalloproteinase (MMP)-2 activity of rat aortic VSMCs in culture, as well as the expression of osteopontin (OPN). Methods Rat aortic VSMCs were grown to confluence and then exposed to 5 mmol/L glucose, 25 mmol/L glucose, or 5 mmol/L alternating with 25 mmol/L glucose in the absence or presence of neutralizing antibodies to OPN, β3 integrin receptor and β5 integrin receptor. The cell proliferation, MMP-2 activity and the expression of OPN were assessed. Results In cultured VSMCs, treatment with constant or intermittent high glucose significantly increased [ 3H]thymidine incorporation in a time-dependent manner. A modest increase was observed at 12 h, and further deteriorated afterwards, and reached the maximum expression at 48 h. However, [ 3H]thymidine incorporation was more pronounced in intermittent high glucose than in constant high glucose. Treatment with constant high glucose for 48 h significantly increase cell number, MMP-2 activation, OPN protein and mRNA expression compared with VSMCs treated with the cells normal glucose, and these effects were further enhanced when VSMCs were treated with intermittent high glucose. In addition, neutralizing antibodies to either OPN or its receptor β3 integrin but not neutralizing antibodies to β5 integrin significantly suppressed increase in [ 3H]thymidine incorporation and MMP-2 activity induced by constant or intermittent high glucose. Conclusions In cultured VSMCs, constant high glucose concentrations enhanced MMP-2 activity, cell proliferation and OPN expression. These effects are enhanced following intermittent exposure to high glucose, indicating that short lived excursions in glycaemic control have important pathological effects on the development of diabetic atherosclerosis, which is mediated by the stimulation of OPN expression and synthesis.