ArticleLiterature Review

Molecular Mechanisms Linking Diabetes to the Accelerated Development of Atherosclerosis

October 2013
Canadian Journal of Diabetes 37(5):345–350

DOI:10.1016/j.jcjd.2013.06.001

Authors:

McMaster University

Le diabète sucré est un facteur de risque indépendant majeur du développement de la maladie cardiovasculaire, et les diabètes de type 1 et de type 2 ont montré qu’ils accéléraient le développement de l’athérosclérose, la cause sous-jacente de la plupart des infarctus du myocarde. En dépit de l’importance clinique cruciale de la maladie vasculaire chez les patients ayant le diabète sucré, notre compréhension des contributions relatives de l’insulinorésistance et de l’hyperglycémie à l’athérogénèse n’est pas complète. De plus, les voies moléculaires et cellulaires qui sont impliquées dans la progression de la maladie ne sont pas claires. Dans cette revue, nous résumons notre compréhension actuelle des mécanismes potentiels qui lient le diabète à l’athérosclérose et indiquons les lacunes que comportent nos connaissances.

Resistance Training in Cardiovascular Diseases: A Review on Its Effectiveness in Controlling Risk Factors

Article

Full-text available

Mar 2024

Cardiovascular Disease (CVD), a term encompassing various disorders affecting the heart and blood vessels, includes coronary artery disease (CAD). CAD is primarily due to the development of atherosclerotic plaques that disrupt blood flow, oxygenation, and nutrient delivery to the myocardium. Risk factors contributing to CAD progression include smoking, hypertension, diabetes mellitus (DM), dyslipidaemia, and obesity. While aerobic exercise (AE) has shown promising results in controlling CVD risk factors, the impact of resistance training (RT) has not been extensively investigated. This review aims to describe the effects of RT on CVD risk factors based on studies retrieved from PubMed and Google Scholar databases. Both isometric and isotonic RT have been found to decrease systolic blood pressure (SBP), diastolic blood pressure, or mean arterial pressure, with SBP showing a more significant reduction. Hypertensive patients engaging in RT alongside a calorie-restricted diet demonstrated significant improvements in blood pressure. RT is associated with increased nitric oxide bioavailability, sympathetic modulation, and enhanced endothelial function. In type-2 DM patients, 8–12 weeks of RT led to improvements in fasting blood glucose levels, insulin secretion, metabolic syndrome risk, and glucose transporter numbers. Combining AE with RT had a more significant impact in reducing insulin resistance and enhancing blood glucose compared to performing exercises separately. It also significantly decreased total cholesterol, triglycerides, and low-density lipoprotein levels while increasing high-density lipoprotein within 12 weeks of application. However, improvements are considered insignificant when lipid levels are already low to normal at baseline. The administration of RT resulted in weight loss and improved body mass index, with more pronounced effects seen when combining AE with RT and a calorie-restricted diet. Considering these results, the administration of RT, either alone or in combination with AE, proves beneficial in rehabilitating CAD patients by improving various risk factors.

Effects of insulin on the proliferation and global gene expression profile of A7r5 cells

Article

Full-text available

Jul 2020

The Diabetes Mellitus–Atherosclerosis Connection: The Role of Lipid and Glucose Metabolism and Chronic Inflammation

Article

Full-text available

Mar 2020
INT J MOL SCI

Diabetes mellitus comprises a group of carbohydrate metabolism disorders that share a common main feature of chronic hyperglycemia that results from defects of insulin secretion, insulin action, or both. Insulin is an important anabolic hormone, and its deficiency leads to various metabolic abnormalities in proteins, lipids, and carbohydrates. Atherosclerosis develops as a result of a multistep process ultimately leading to cardiovascular disease associated with high morbidity and mortality. Alteration of lipid metabolism is a risk factor and characteristic feature of atherosclerosis. Possible links between the two chronic disorders depending on altered metabolic pathways have been investigated in numerous studies. It was shown that both types of diabetes mellitus can actually induce atherosclerosis development or further accelerate its progression. Elevated glucose level, dyslipidemia, and other metabolic alterations that accompany the disease development are tightly involved in the pathogenesis of atherosclerosis at almost every step of the atherogenic process. Chronic inflammation is currently considered as one of the key factors in atherosclerosis development and is present starting from the earliest stages of the pathology initiation. It may also be regarded as one of the possible links between atherosclerosis and diabetes mellitus. However, the data available so far do not allow for developing effective anti-inflammatory therapeutic strategies that would stop atherosclerotic lesion progression or induce lesion reduction. In this review, we summarize the main aspects of diabetes mellitus that possibly affect the atherogenic process and its relationship with chronic inflammation. We also discuss the established pathophysiological features that link atherosclerosis and diabetes mellitus, such as oxidative stress, altered protein kinase signaling, and the role of certain miRNA and epigenetic modifications.

Serum discrimination and phenotype assessment of coronary artery disease patents with and without type 2 diabetes prior to coronary artery bypass graft surgery

Article

Full-text available

Aug 2020
PLOS ONE

Diabetes Mellitus (DM) accelerates coronary artery disease (CAD) and atherosclerosis, the causes of most heart attacks. The biomolecules involved in these inter-related disease processes are not well understood. This study analyzes biomolecules in the sera of patients with CAD, with and without type (T) 2DM, who are about to undergo coronary artery bypass graft (CABG) surgery. The goal is to develop methodology to help identify and monitor CAD patients with and without T2DM, in order to better understand these phenotypes and to glean relationships through analysis of serum biomolecules. Aorta, fat, muscle, and vein tissues from CAD T2DM patients display diabetic-related histologic changes (e.g., lipid accumulation, fibrosis, loss of cellularity) when compared to non-diabetic CAD patients. The patient discriminatory methodology utilized is serum biomolecule mass profiling. This mass spectrometry (MS) approach is able to distinguish the sera of a group of CAD patients from controls (p value 10⁻¹⁵), with the CAD group containing both T2DM and non-diabetic patients. This result indicates the T2DM phenotype does not interfere appreciably with the CAD determination versus control individuals. Sera from a group of T2DM CAD patients however are distinguishable from non-T2DM CAD patients (p value 10⁻⁸), indicating it may be possible to examine the T2DM phenotype within the CAD disease state with this MS methodology. The same serum samples used in the CAD T2DM versus non-T2DM binary group comparison were subjected to MS/MS peptide structure analysis to help identify potential biochemical and phenotypic changes associated with CAD and T2DM. Such peptide/protein identifications could lead to improved understanding of underlying mechanisms, additional biomarkers for discriminating and monitoring these disease conditions, and potential therapeutic targets. Bioinformatics/systems biology analysis of the peptide/protein changes associated with CAD and T2DM suggested cell pathways/systems affected include atherosclerosis, DM, fibrosis, lipogenesis, loss of cellularity (apoptosis), and inflammation.

Activated protein C reverses epigenetically sustained p66Shc expression in plaque-associated macrophages in diabetes

Article

Full-text available

Aug 2018

Impaired activated protein C (aPC) generation is associated with atherosclerosis and diabetes mellitus. Diabetes-associated atherosclerosis is characterized by the hyperglycaemic memory, e.g., failure of disease improvement despite attenuation of hyperglycaemia. Therapies reversing the hyperglycaemic memory are lacking. Here we demonstrate that hyperglycaemia, but not hyperlipidaemia, induces the redox-regulator p66Shc and reactive oxygen species (ROS) in macrophages. p66Shc expression, ROS generation, and a pro-atherogenic phenotype are sustained despite restoring normoglycemic conditions. Inhibition of p66Shc abolishes this sustained pro-atherogenic phenotype, identifying p66Shc-dependent ROS in macrophages as a key mechanism conveying the hyperglycaemic memory. The p66Shc-associated hyperglycaemic memory can be reversed by aPC via protease-activated receptor-1 signalling. aPC reverses glucose-induced CpG hypomethylation within the p66Shc promoter by induction of the DNA methyltransferase-1 (DNMT1). Thus, epigenetically sustained p66Shc expression in plaque macrophages drives the hyperglycaemic memory, which—however—can be reversed by aPC. This establishes that reversal of the hyperglycaemic memory in diabetic atherosclerosis is feasible.

TLR4 Antagonist Attenuates Atherogenesis in LDL Receptor-Deficient Mice with Diet-Induced Type 2 Diabetes

Article

Jun 2015
IMMUNOBIOLOGY

Although a large number of studies have well documented a key role of toll-like receptor (TLR)4 in atherosclerosis, it remains undetermined if TLR4 antagonist attenuates atherogenesis in mouse model for type 2 diabetes. In this study, we induced type 2 diabetes in low-density lipoprotein receptor-deficient (LDLR(-/-)) mice by high-fat diet (HFD). At 8 weeks old, 20 mice were fed HFD and 20 mice fed regular chow (RC) for 24 weeks. In the last 10 weeks, half HFD-fed mice and half RC-fed mice were treated with Rhodobacter sphaeroides lipopolysaccharide (Rs-LPS), an established TLR4 antagonist. After the treatment, atherosclerotic lesions in aortas were analyzed. Results showed that the HFD significantly increased bodyweight, glucose, lipids including total cholesterol, triglycerides and free fatty acids, and insulin resistance, indicating that the HFD induced type 2 diabetes in LDLR(-/-) mice. Results also showed that Rs-LPS had no effect on HFD-increased metabolic parameters in both nondiabetic and diabetic mice. Lipid staining of aortas and histological analysis of cross-sections of aortic roots showed that diabetes increased atherosclerotic lesions, but Rs-LPS attenuated atherogenesis in diabetic mice. Furthermore, immunohistochemical studies showed that Rs-LPS reduced infiltration of monocytes/macrophages and expression of interleukin (IL)-6 and matrix metalloproteinase-9 in atherosclerotic lesions of diabetic mice. Finally, the antagonistic effect of Rs-LPS on TLR4 was demonstrated by our in vitro studies showing that Rs-LPS inhibited IL-6 secretion from macrophages and endothelial cells stimulated by LPS or LPS plus saturated fatty acid palmitate. Taken together, our study demonstrated that TLR4 antagonist was capable of attenuating vascular inflammation and atherogenesis in mice with HFD-induced type 2 diabetes. Published by Elsevier GmbH.

In Association with Other Risk Factors, Smoking Is the Main Predictor for Lower Transcutaneous Oxygen Pressure in Type 2 Diabetes

Article

Full-text available

Feb 2024

Type 2 diabetes mellitus (T2DM) significantly increases the risk of peripheral artery disease (PAD), and diabetes is the leading cause of nontraumatic amputations. This study investigated the risk factors for transcutaneous oxygen pressure (TcPO2) in T2DM, a noninvasive method to quantify skin oxygenation and the underlying microvascular circulation. The study included 119 T2DM patients (91 male/28 female). TcPO2 measurements were conducted with the Tina TCM4 Series transcutaneous monitor (Radiometer, Copenhagen, Sweden) and skin electrodes. Patients with TcPO2 < 40 mmHg were younger (p = 0.001), had significantly higher systolic blood pressure (SBP) (p = 0.023), glycated hemoglobin (HbA1c) (p = 0.013), fasting plasma glucose (fPG) (p = 0.038), total cholesterol (p = 0.006), LDL cholesterol (p = 0.004), and had more frequent smoking habits (p = 0.001) than those with TcPO2 ≥ 40 mmHg. The main predictors for the TcPO2 value (R2 = 0.211) obtained via stepwise regression analysis were age, smoking, SBP, HbA1c, fPG, and total and LDL cholesterol. Among all the listed predictors, smoking, HbA1c, and LDL cholesterol were found to be the most significant, with negative parameter estimates of −3.051310 (p = 0.0007), −2.032018 (p = 0.0003), and −2.560353 (p = 0.0046). The results of our study suggest that in association with other risk factors, smoking is the main predictor for lower TcPO2 in T2DM.

The Relationship between the Angiographic Atherosclerotic Burden and the Inflammatory Factors in Diabetic and Non-Diabetic Patients with Coronary Artery Disease

Article

Full-text available

Oct 2023

Veysel Tosun

Objective: Inflammation is a known pathophysiological feature that is common in both diabetes mellitus (DM) and atherosclerosis. High-density lipoprotein (HDL) is an anti-atherogenic lipoprotein and has an inverse relationship with coronary artery disease (CAD). In the present study, the association between the severity of CAD and inflammatory parameters neutrophil to HDL (NHR), lymphocyte to HDL (LHR), and platelet to HDL (PHR) was investigated. Methods: In this single-center prospective study, 98 diabetic (type 2 DM), and 320 non-diabetic CAD patients who underwent coronary angiography were enrolled. Baseline demographic characteristics were recorded, hematologic and biochemical samples were measured, the angiographic profile was analyzed, SYNTAX and Gensini scores were calculated for all patients. Results: Hypertension and smoking rates and HbA1c were higher in the diabetic group (p:0.001, p<0.001, p<0.001, respectively). NHR, LHR, and PHR were significantly higher in the diabetic group compared with the non-diabetic group (p:0.007, p:0.002, p:0.005, respectively). The diabetic group had higher SYNTAX and Gensini scores (p<0.001 for both). NHR, LHR, PHR, age, and hemoglobin were positively correlated with both SYNTAX and Gensini scores in the correlation analysis. Univariate and multivariate analyses showed that NHR, LHR, SYNTAX and Gensini scores were found to be independent predictors of DM in CAD patients. Conclusion: Our study demonstrated that the inflammatory parameters NHR, LHR, and PHR and atherosclerotic burden parameters SYNTAX and Gensini scores were worsening in diabetic patients. NHR, LHR, and PHR were significantly associated with higher SYNTAX and Gensini scores in diabetic and nondiabetic patients

The association of Cardiac Valve Calcification and 1-year Mortality after Lower-extremity Amputation in Diabetic Patients: a retrospective study

Preprint

Full-text available

Oct 2022

Background: Cardiac valve calcification predisposes patients to a higher risk of adverse events. This study aimed to investigate the association between cardiac valve calcification and 1-year mortality in diabetic patients after lower-extremity amputation. Methods: Diabetic patients requiring lower-extremity amputation were retrospectively studied. Preoperative detailed anamnesis was taken. Cardiac valve calcification was assessed using echocardiography at baseline. One-year follow-up was conducted and included clinical visits, hospital record assessment, and telephone reviews to obtain the survival status of patients. Results: Ninety-three diabetic patients participated in the study. The 1-year follow-up mortality rate after amputation was 24.7%. Compared to the survival group, the prevalence of cardiac valve calcification and RCRI were higher in the mortality group. In the Cox regression analysis, cardiac valvular calcification (HR=3.427, 95% CI=1.125-10.443, P=0.030) was found to be an independent predictor of all-cause mortality after amputation. In addition, the patients with both aortic valve calcification and mitral annular calcification had a higher all-cause mortality rate (50%). Receiver operator characteristic curve analysis showed a stronger predictive ability when using a combination of calcified valve number and RCRI (AUC=0.786 95%, CI=0.676-0.896, P=0.000). Conclusion: In diabetic patients after lower-extremity amputation, cardiac valve calcification was associated with all-cause mortality during 1-year follow-up. Combination of calcified valves number and RCRI showed a stronger predictive valuefor mortality.

Hypercoagulability Impairs Plaque Stability in Diabetes-Induced Atherosclerosis

Article

Full-text available

May 2022

Diabetes mellitus, which is largely driven by nutritional and behavioral factors, is characterized by accelerated atherosclerosis with impaired plaque stability. Atherosclerosis and associated complications are the major cause of mortality in diabetic patients. Efficient therapeutic concepts for diabetes-associated atherosclerosis are lacking. Atherosclerosis among diabetic patients is associated with reduced endothelial thrombomodulin (TM) expression and impaired activated protein C (aPC) generation. Here, we demonstrate that atherosclerotic plaque stability is reduced in hyperglycemic mice expressing dysfunctional TM (TMPro/Pro mice), which have a pro-coagulant phenotype due to impaired thrombin inhibition and markedly reduced aPC generation. The vessel lumen and plaque size of atherosclerotic lesions in the truncus brachiocephalic were decreased in diabetic TMPro/Pro ApoE-/- mice compared to diabetic ApoE-/- mice. While lipid accumulation in lesions of diabetic TMPro/Pro ApoE-/- mice was lower than that in diabetic ApoE-/- mice, morphometric analyses revealed more prominent signs of instable plaques, such as a larger necrotic core area and decreased fibrous cap thickness in diabetic TMPro/Pro ApoE-/- mice. Congruently, more macrophages and fewer smooth muscle cells were observed within lesions of diabetic TMPro/Pro ApoE-/- mice. Thus, impaired TM function reduces plaque stability, a characteristic of hyperglycemia-associated plaques, thus suggesting the crucial role of impaired TM function in mediating diabetes-associated atherosclerosis.

Epigenetic Modifications and Non-Coding RNA in Diabetes-Mellitus-Induced Coronary Artery Disease: Pathophysiological Link and New Therapeutic Frontiers

Article

Full-text available

Apr 2022
INT J MOL SCI

Diabetes mellitus (DM) is a glucose metabolism disorder characterized by chronic hyperglycemia resulting from a deficit of insulin production and/or action. DM affects more than 1 in 10 adults, and it is associated with an increased risk of cardiovascular morbidity and mortality. Cardiovascular disease (CVD) accounts for two thirds of the overall deaths in diabetic patients, with coronary artery disease (CAD) and ischemic cardiomyopathy as the main contributors. Hyperglycemic damage on vascular endothelial cells leading to endothelial dysfunction represents the main initiating factor in the pathogenesis of diabetic vascular complications; however, the underlying pathophysiological mechanisms are still not entirely understood. This review addresses the current knowledge on the pathophysiological links between DM and CAD with a focus on the role of epigenetic modifications, including DNA methylation, histone modifications and noncoding RNA control. Increased knowledge of epigenetic mechanisms has contributed to the development of new pharmacological treatments (“epidrugs”) with epigenetic targets, although these approaches present several challenges. Specific epigenetic biomarkers may also be used to predict or detect the development and progression of diabetes complications. Further studies on diabetes and CAD epigenetics are needed in order to identify possible new therapeutic targets and advance personalized medicine with the prediction of individual drug responses and minimization of adverse effects.

Review ARTICLE: Diabetes Mellitus: A Path to Amnesia, Personality, and Behavior Change

Article

Full-text available

Feb 2022

ype 2 diabetes mellitus is increasingly being associated with cognition dysfunction. Dementia, including vascular dementia and Alzheimer’s Disease, is being recognized as comorbidities of this metabolic disorder. The progressive hallmarks of this cognitive dysfunction include mild impairment of cognition and cognitive decline. Dementia and mild impairment of cognition appear primarily in older patients. Studies on risk factors, neuropathology, and brain imaging have provided important suggestions for mechanisms that lie behind the development of dementia. It is a significant challenge to understand the disease processes related to diabetes that affect the brain and lead to dementia development. The connection between diabetes mellitus and dysfunction of cognition has been observed in many human and animal studies that have noted that mechanisms related to diabetes mellitus are possibly responsible for aggravating cognitive dysfunction. This article attempts to narrate the possible association between Type 2 diabetes and dementia, reviewing studies that have noted this association in vascular dementia and Alzheimer’s Disease and helping to explain the potential mechanisms behind the disease process. A Google search for “Diabetes Mellitus and Dementia” was carried out. Search was also done for “Diabetes Mellitus”, “Vascular Dementia”, and “Alzheimer’s Disease”. The literature search was done using Google Scholar, Pubmed, Embase, ScienceDirect, and MEDLINE. Keeping in mind the increasing rate of Diabetes Mellitus, it is important to establish the Type 2 diabetes’ effect on the brain and diseases of neurodegeneration. This narrative review aims to build awareness regarding the different types of dementia and their relationship with diabetes.

Diabetes Mellitus: A path to Amnesia, Personality and Behavior Change.

Preprint

Full-text available

Jan 2022

Type 2 Diabetes Mellitus is being increasingly associated with dysfunction of cognition. Dementia, including vascular dementia and Alzheimer’s disease, is being recognized as comorbidities of this metabolic disorder. The progressive hallmarks of this cognitive dysfunction include mild impairment of cognition and cognitive decline. Dementia and mild impairment of cognition appear in older patients primarily. Studies on risk factors, neuropathology, and brain imaging have provided important suggestions for mechanisms that lie behind the development of dementia. It is a significant challenge to understand the disease processes related to diabetes which affect the brain and lead to dementia development. The connection between Diabetes Mellitus and dysfunction of cognition has been observed in many human and animal studies that have noted mechanisms related to Diabetes Mellitus are possibly responsible for aggravating cognitive dysfunction. This article attempts to narrate the possible association between type 2 diabetes and Dementia, reviewing studies that have noted this association in vascular dementia and Alzheimer’s disease and helping to explain the potential mechanisms behind the disease process. The Google search for ‘Diabetes Mellitus and Dementia’ was carried out. Also, the search was done using ‘Diabetes Mellitus,’ ‘Vascular Dementia,’ ‘Alzheimer’s Disease.’ The literature search was done from Google Scholar, Pubmed, Embase, ScienceDirect, and MEDLINE. Keeping in mind the increasing rate of Diabetes Mellitus, it is important to establish the type 2 diabetes effect on the brain and diseases of neurodegeneration. This narrative review aims to build awareness regarding different types of dementia and their relationship with diabetes.

Glucagon-Like Peptide-1 Receptor Agonists and Brain Vascular Function

Article

Full-text available

Aug 2021

Prevention of a cardiovascular incident and a regression of atherosclerotic changes are considered to be the primary aims of preventive cardiovascular medicine. Arterial thrombosis is caused by endothelial dysfunction, which disrupts vascular haemostasis. Glucagon-like peptide 1 (GLP-1) receptor agonists have been initially used as glucose- lowering agents but, over time, have been used for the treatment of other indications, due to their cardio-renal benefit, as well as their effect on the regression of an atherosclerotic process. The aim of this review is to summarise the benefits of the GLP- 1 receptor agonists/analogues in the prevention of atherosclerotic changes and the preservation of brain’s vascular function, as well as to discuss their potential impact on neurodegenerative processes, namely the neuropathology of Alzheimer’s disease. In this review, we focused on the following: 1) human clinical trials, in which safety and cardioprotective effects of GLP-1 receptor agonists/analogues were investigated, 2) preclinical trials, in which the effects of GLP-1 receptor agonists/analogues were investigated, in animal models of Alzheimer’s disease, in which cognitive function was analysed through behavioural tests, and 3) human clinical trials, in which the effects of GLP-1 receptor agonists/analogues on cognitive decline were examined, in patients diagnosed with probable Alzheimer’s disease. Keywords: Alzheimer’s disease, atherosclerosis, glucagon-like peptide 1, neurodegenerative diseases, therapeutics.

S-nitrosylation-mediated coupling of G-protein alpha-2 with CXCR5 induces Hippo/YAP-dependent diabetes-accelerated atherosclerosis

Article

Full-text available

Jul 2021

Atherosclerosis-associated cardiovascular disease is one of the main causes of death and disability among patients with diabetes mellitus. However, little is known about the impact of S-nitrosylation in diabetes-accelerated atherosclerosis. Here, we show increased levels of S-nitrosylation of guanine nucleotide-binding protein G(i) subunit alpha-2 (SNO-GNAI2) at Cysteine 66 in coronary artery samples from diabetic patients with atherosclerosis, consistently with results from mice. Mechanistically, SNO-GNAI2 acted by coupling with CXCR5 to dephosphorylate the Hippo pathway kinase LATS1, thereby leading to nuclear translocation of YAP and promoting an inflammatory response in endothelial cells. Furthermore, Cys-mutant GNAI2 refractory to S-nitrosylation abrogated GNAI2-CXCR5 coupling, alleviated atherosclerosis in diabetic mice, restored Hippo activity, and reduced endothelial inflammation. In addition, we showed that melatonin treatment restored endothelial function and protected against diabetes-accelerated atherosclerosis by preventing GNAI2 S-nitrosylation. In conclusion, SNO-GNAI2 drives diabetes-accelerated atherosclerosis by coupling with CXCR5 and activating YAP-dependent endothelial inflammation, and reducing SNO-GNAI2 is an efficient strategy for alleviating diabetes-accelerated atherosclerosis.

CircRNA-DAPK1 promotes vascular cell pyroptosis in diabetes by regulating the circ-DAPK1/miR-4454/TXNIP axis.

Preprint

Full-text available

Feb 2021

Background Circular RNAs have been demonstrated to play an important role in the development of vascular diseases. However, little is known about the role of circ-021774, also named circ-DAPK1, in vascular cell pyroptosis. Methods Circ-DAPK1 was selected from circular RNA sequencing data of HUVECs treated with high glucose medium and normal medium. RT-qPCR was used to determine the expression of circ-DAPK1 in vivo and in vitro. Dual luciferase reporter assay, fluorescence in situ hybridization (FISH) and RNA immunoprecipitation (RIP) were performed to prove the interaction of circ-DAPK1, miRNA-4454 and thioredoxin-interactingprotein (TXNIP). Adeno-associated virus (AAV) was injected intravenously to establish mouse models. PI staining, western-blot and transmission electron microscopy (TEM) analyses were performed to identify the role of circ-DAPK1 in promoting pyroptosis. Results We found that circ-DAPK1 was highly expressed in high glucose medium cultured HUVECs and db/db mice. In vitro and in vivo experiments demonstrated that circ-DAPK1 knockdown decreased the number of PI⁺ cells, the expression of ASC, NLRP3, GSDMD-N, cleaved caspase-1, IL-18 and IL-1β. In a mechanistic study, the circ-DAPK1/miRNA-4454/TXNIP signaling axis was demonstrated to promote vascular cell pyroptosis in diabetes. Conclusions Circ-DAPK1 functions as a promoter of vascular cell pyroptosis in diabetes via the circ-DAPK1/miRNA-4454/TXNIP signaling axis.

Effects of insulin on the proliferation and global gene expression profile of A7r5 cells

Article

Full-text available

Feb 2021
MOL BIOL REP

Insulin contributes to atherosclerosis, but the potential mechanisms are kept unclear. In this study, insulin promoted proliferation of A7r5 cells. Microarray analysis indicated that insulin significantly changed 812 probe sets of genes, including 405 upregulated and 407 downregulated ones (fold change ≥ 1.5 or ≤ - 1.5; p < 0.05). Gene ontology analysis showed that the differentially expressed genes were involved in a number of processes, including the regulation of cell proliferation/migration/cycle, apoptotic process, oxidative stress, inflammatory response, mitogen-activated protein kinase (MAPK) activity, lipid metabolic process and extracellular matrix organization. Moreover, Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that the genes were involved in biosynthesis of amino acids, fatty acid metabolism, glycolysis/gluconeogenesis, metabolic pathways, regulation of autophagy, cell cycle and apoptosis, as well as the PI3K-Akt, MAPK, mTOR and NF-κB signaling pathways. Additionally, insulin enhanced phosphorylation of MAPK kinase 1/2 and Akt, suggesting activation of the MAPK and PI3K-Akt signaling pathways. Inhibition of ERK1/2 reduced insulin-induced proliferation. This study revealed the proliferative effects of insulin and displayed global gene expression profile of A7r5 cells stimulated by insulin, suggesting new insight into the molecular pathogenesis of insulin promoting atherosclerosis.

Pathophysiology of Type 2 Diabetes Mellitus

Article

Full-text available

Aug 2020
INT J MOL SCI

Type 2 Diabetes Mellitus (T2DM), one of the most common metabolic disorders, is caused by a combination of two primary factors: defective insulin secretion by pancreatic β-cells and the inability of insulin-sensitive tissues to respond appropriately to insulin. Because insulin release and activity are essential processes for glucose homeostasis, the molecular mechanisms involved in the synthesis and release of insulin, as well as in its detection are tightly regulated. Defects in any of the mechanisms involved in these processes can lead to a metabolic imbalance responsible for the development of the disease. This review analyzes the key aspects of T2DM, as well as the molecular mechanisms and pathways implicated in insulin metabolism leading to T2DM and insulin resistance. For that purpose, we summarize the data gathered up until now, focusing especially on insulin synthesis, insulin release, insulin sensing and on the downstream effects on individual insulin-sensitive organs. The review also covers the pathological conditions perpetuating T2DM such as nutritional factors, physical activity, gut dysbiosis and metabolic memory. Additionally, because T2DM is associated with accelerated atherosclerosis development, we review here some of the molecular mechanisms that link T2DM and insulin resistance (IR) as well as cardiovascular risk as one of the most important complications in T2DM.

Identification of Susceptibility Modules and Genes for Cardiovascular Disease in Diabetic Patients Using WGCNA Analysis

Article

Full-text available

May 2020

Objective: To identify susceptibility modules and genes for cardiovascular disease in diabetic patients using weighted gene coexpression network analysis (WGCNA). Methods: The raw data of GSE13760 were downloaded from the Gene Expression Omnibus (GEO) website. Genes with a false discovery rate < 0.05 and a log2 fold change ≥ 0.5 were included in the analysis. WGCNA was used to build a gene coexpression network, screen important modules, and filter the hub genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed for the genes in modules with clinical interest. Genes with a significance over 0.2 and a module membership over 0.8 were used as hub genes. Subsequently, we screened these hub genes in the published genome-wide SNP data of cardiovascular disease. The overlapped genes were defined as key genes. Results: Fourteen gene coexpression modules were constructed via WGCNA analysis. Module greenyellow was mostly significantly correlated with diabetes. The GO analysis showed that genes in the module greenyellow were mainly enriched in extracellular matrix organization, extracellular exosome, and calcium ion binding. The KEGG analysis showed that the genes in the module greenyellow were mainly enriched in antigen processing and presentation, phagosome. Fifteen genes were identified as hub genes. Finally, HLA-DRB1, LRP1, and MMP2 were identified as key genes. Conclusion: This was the first study that used the WGCNA method to construct a coexpression network to explore diabetes-associated susceptibility modules and genes for cardiovascular disease. Our study identified a module and several key genes that acted as essential components in the etiology of diabetes-associated cardiovascular disease, which may enhance our fundamental knowledge of the molecular mechanisms underlying this disease.

N ε -Carboxymethyl-Lysine Negatively Regulates Foam Cell Migration via the Vav1/Rac1 Pathway

Article

Full-text available

Feb 2020

Background: Macrophage-derived foam cells play a central role in atherosclerosis, and their ultimate fate includes apoptosis, promotion of vascular inflammation, or migration to other tissues. Nε-Carboxymethyl-lysine (CML), the key active component of advanced glycation end products, induced foam cell formation and apoptosis. Previous studies have shown that the Vav1/Rac1 pathway affects the macrophage cytoskeleton and cell migration, but its role in the pathogenesis of diabetic atherosclerosis is unknown. Methods and results: In this study, we used anterior tibiofibular vascular samples from diabetic foot amputation patients and accident amputation patients, and histological and cytological tests were performed using a diabetic ApoE-/- mouse model and primary peritoneal macrophages, respectively. The results showed that the atherosclerotic plaques of diabetic foot amputation patients and diabetic ApoE-/- mice were larger than those of the control group. Inhibition of the Vav1/Rac1 pathway reduced vascular plaques and promoted the migration of macrophages to lymph nodes. Transwell and wound healing assays showed that the migratory ability of macrophage-derived foam cells was inhibited by CML. Cytoskeletal staining showed that advanced glycation end products inhibited the formation of lamellipodia in foam cells, and inhibition of the Vav1/Rac1 pathway restored the formation of lamellipodia. Conclusion: CML inhibits the migration of foam cells from blood vessels via the Vav1/Rac1 pathway, and this process affects the formation of lamellipodia.

Treatment of Peroxidase Derived from Foxtail Millet Bran Attenuates Atherosclerosis by Inhibition of CD36 and STAT3 in Vitro and in Vivo

Article

Jan 2020

Atherosclerosis is one of the main causes of cardiovascular diseases. Our previous study indicated that a type of peroxidase derived from foxtail millet bran (FMBP) had prominent antitumor activities. In the present study, we found that FMBP had potential antiatherosclerosis effects. The results showed that FMBP treatment strongly suppressed lipid phagocytosis in both HASMCs and THP-1 cells by 52% and 49%, respectively. Further, FMBP significantly inhibited HASMCs migration by promoting transformation of HASMCs from synthetic to contractile, leading to the decrease of lipid phagocytosis. Simultaneously, FMBP repressed lipid uptake by reducing the expression of CD36 in THP-1 cells. In addition, FMBP reduced the secretion of inflammatory factor IL-1β by inhibiting the expression of STAT3 in THP-1 cells. Interestingly, FMBP also had the same effects in models of atherosclerosis constructed with ApoE-/- mice, including decreased aortic lesion area, repressed aortic sinus CD36 and STAT3 expression, and elevated serum HDL-C concentration. Collectively, these results indicate that FMBP has great potential in preventing the development of atherosclerosis.

Dyslipidemia and Its Role in the Pathogenesis of Atherosclerotic Cardiovascular Disease: Implications for Evaluation and Targets for Treatment of Dyslipidemia Based on Recent Guidelines

Chapter

Full-text available

Apr 2019

MicroRNA profiling of diabetic atherosclerosis in a rat model

Article

Full-text available

Nov 2018

Objective The incidence of diabetic atherosclerosis (DA) is increasing worldwide. The study aim was to identify differentially expressed microRNAs (DE-miRs) potentially associated with the initiation and/or progression of DA, thereby yielding new insights into this disease. Methods Matched iliac artery tissue samples were isolated from 6 male rats with or without DA. The Affymetrix GeneChip microRNA 4.0 Array was used to detect miRs. Differential expression between atherosclerotic group and non-atherosclerotic group samples was analyzed using the Gene-Cloud of Biotechnology Information platform. Targetscan and miRanda were then used to predict targets of DE-miRs. Functions and pathways were identified for significantly enriched candidate target genes and a DE-miR functional regulatory network was assembled to identify DA-associated core target genes. Results A total of nine DE-miRs (rno-miR-206-3p, rno-miR-133a-5p, rno-miR-133b-3p, rno-miR-133a-3p, rno-miR-325-5p, rno-miR-675-3p, rno-miR-411-5p, rno-miR-329-3p, and rno-miR-126a-3p) were identified, all of which were up-regulated and together predicted to target 3349 genes. The target genes were enriched in known functions and pathways related to lipid and glucose metabolism. The functional regulatory network indicated a modulatory pattern of these metabolic functions with DE-miRs. The miR-gene network suggested arpp19 and MDM4 as possible DA-related core target genes. Conclusion The present study identified DE-miRs and miRNA-gene networks enriched for lipid and glucose metabolic functions and pathways, and arpp19 and MDM4 as potential DA-related core target genes, suggesting DE-miRs and/or arpp19 and MDM4 could act as potential diagnostic markers or therapeutic targets for DA. Electronic supplementary material The online version of this article (10.1186/s40001-018-0354-5) contains supplementary material, which is available to authorized users.

Alpha-amylase inhibitors from mycelium of an oyster mushroom

Article

Full-text available

Jul 2018

The α-Amylase and α-glucosidase are two main enzymes involved in carbohydrate metabolism. This study was aimed at detecting alpha-amylase inhibitory activity from edible mushroom mycelia. Oyster mushroom was collected from a natural source, from Indian Institute of Technology (Banaras Hindu University) campus and was maintained in vitro in mycelial form. Chloroform, acetone, methanol, and water were used separately for extraction of an active constituent from mycelial cells grown, for 7 days, in potato dextrose broth. The extracts were tested for alpha-amylase inhibitory activity. Chloroform, acetone, and methanol extracts were found to have alpha-amylase inhibitory activity, with IC50 values of 1.71, 224, and 383 μg/mL, respectively. Aqueous extract had no enzyme inhibitory activity. The acetone extract inhibited α-amylase non-competitively whereas chloroform extract showed competitive inhibition. Acetone extraction yielded highest total phenolic content (TPC) of 0.524 mM of gallic acid equivalent, whereas chloroform extraction resulted in lowest TPC of 0.006 mM. The HPLC and absorbance maxima of acetone and chloroform extracts suggest that the bioactive component responsible for enzyme inhibition could be glycoproteins in chloroform extract and catechins (flavonoids) in acetone extract. Thus, the mushroom mycelia under study may be exploited for production and purification of a lead compound for the development of the α-amylase inhibitory drug.

Ginsenoside Rg3 Mitigates Atherosclerosis Progression in Diabetic apoE–/– Mice by Skewing Macrophages to the M2 Phenotype

Article

Full-text available

May 2018

Atherosclerosis (AS) in diabetic patients is often associated with low stability, which might be largely attributed to unfavorable macrophage polarization and increased inflammatory response induced by hyperglycaemia. Ginsenoside Rg3 is one of the main active principles of Panax Ginseng, which has been reported to be a natural ligand of peroxisome proliferator-activated receptor-gamma (PPARγ), a key nuclear transcriptional factor involved in inflammation and macrophage differentiation. However, it remains unclear if Rg3 could exert protective effects on plaque stability in diabetes. In this study, we investigated the role of ginsenoside 20(S)-Rg3 in macrophage polarization and AS plaque stability using advanced glycation end products-treated macrophages and diabetic AS mice models. In vitro, advanced glycation end products (AGEs) treatment promoted the expression of proinflammatory molecules and M1 surface markers, whereas 20(S)-Rg3 could reverse the M1 polarization to the M2 phenotype. In vivo, the administration of 20(S)-Rg3 promoted AS lesion stability and reduced the plaque burden, accompanied by increased M2 macrophages and reduced M1 macrophages. In addition, PPARγ antagonist GW9662 co-administration mostly blocked these effects, suggesting the important role of PPARγ pathways in mediating 20(S)-Rg3 effects in macrophage polarization and atherosclerosis progression. Together, these results demonstrated an immunomodulatory role of ginsenoside 20(S)-Rg3 in promoting macrophages to a profile of the M2 type through PPARγ-dependent mechanisms, and indicated a potential role of 20(S)-Rg3 in the prevention and treatment of diabetic atherosclerosis.

Suppression of Abdominal Aortic Aneurysm Formation in Mice by Teneligliptin, a Dipeptidyl Peptidase-4 Inhibitor

Article

Full-text available

Jan 2018

Aim: Dipeptidyl peptidase-4 (DPP-4) inhibitors lower blood glucose levels through inhibition of incretin degradation, which stimulates insulin secretion. Recent studies reported that DPP-4 inhibitors suppressed atherogenesis in apolipoprotein E-knockout (ApoEKO) mice. In this study, we investigated whether teneligliptin, a DPP-4 inhibitor, affects the development of abdominal aortic aneurysms (AAA) in ApoEKO mice. Methods: ApoEKO mice were fed a high-fat diet (HFD) and infused with angiotensin (Ang) II by osmotic mini pumps for 4 weeks to induce AAA with (DPP-4i group) or without (control group) teneligliptin administered orally from 1 week before HFD and Ang II infusion to the end of the experiment. Confluent rat vascular smooth muscle cells (VSMCs) were serum-starved for 48 hours, then incubated with or without teneligliptin for another 24 hours and stimulated with Ang II. Results: Treatment with teneligliptin significantly reduced the AAA formation rate (30.7% vs. 71.4% vs. control, P＜0.05), aortic dilatation (1.32±0.09 mm vs. 1.76±0.18 mm in the control, P＜0.05) and severity score (0.75±0.28 vs. 1.91±0.4 in the control, P＜0.05). Elastin degradation grade was also attenuated in DPP-4i group (2.83±0.17 vs. 3.45±0.16 in the control, P＜0.05). The number of macrophages infiltrating into the abdominal aorta was decreased in the DPP-4i group (51.8± 29.8/section vs. 219.5±78.5/section in the control, P＜0.05). Teneligliptin attenuated Ang II-induced phosphorylation of extracellular signal-regulated kinase (ERK) and Akt, and mRNA expression of monocyte chemoattractant protein-1 in VSMCs. Conclusion: Treatment with teneligliptin suppressed AAA formation in ApoEKO mice with HFD and Ang II infusion. Suppression of macrophage infiltration by teneligliptin may be involved in the inhibition of AAA formation.

Is insulin pro-atherogenic at the cellular level?

Article

Full-text available

Dec 2017

Aim: This study was undertaken to test the hypothesis that insulin treatment has unexpected pro-atherogenic effects at the cellular level, namely, proliferative activity and intracellular cholesterol content. Methods: Primary cultures of subendothelial cells derived from non-atherosclerotic human aorta and mouse peritoneal macrophages were used to investigate the in vitro effect of insulin on atherosclerosis-related parameters, such as cellular cholesterol content and proliferation rate. Additionally, the effect of insulin treatment in 33 type 1 diabetic patients on serum atherogenicity (i.e. its ability to induce cholesterol accumulation in cultured cells) was investigated. Results: Insulin (1-1,000 µU/mL) did not affect [³H]-thymidine incorporation or cholesterol content in either type of cultured cell. Most blood sera obtained from type 1 diabetic patients induced a 1.5- to 1.7-fold increase in cholesterol content of cultured cells, but this effect did not correlate with serum insulin levels. Exogenous insulin added to cultured cells did not modify the effect of patient's sera on cholesterol level and proliferation of cultured cells. Conclusion: The results suggest that insulin does not exert direct atherogenic actions at the level of arterial cells, with the respect to proliferative activity and cholesterol content.

Cardiovascular inflammation is reduced with methotrexate in diabetes

Article

Full-text available

Aug 2017
MOL CELL BIOCHEM

Diabetes increases the risk of vascular events and mortality. While earlier type 2 diabetes trials demonstrated that intensive glucose lowering reduces microvascular complications, it is only recently that treatment with some of the newer antihyperglycemic agents has been associated with macrovascular benefits. We report herein that db/db mice concomitantly fed the Western diet and treated with the anti-inflammatory agent methotrexate display a less aggressive inflammatory (lower serum IL-1β, IL-6, SDF-1, and TNFα levels; higher circulating adiponectin, IL-12p70 and IL-10 concentrations; lower aortic VCAM-1 levels) profile than their saline-treated counterpart. Furthermore, acetylcholine-elicited endothelium-dependent vasodilatation was significantly greater in thoracic aortic segments from the former group. Collectively, the data lend support to the notion that alterations in the inflammatory system may be involved in the macrovascular benefits observed in type 2 diabetes trials and provide credence for the development of anti-inflammatory tools to lower CV risk and CV events in diabetes.

Anagliptin, A Dipeptidyl Peptidase-4 Inhibitor Ameliorates Arterial Stiffness in Association with Reduction of Remnant-Like Particle Cholesterol and Alanine Transaminase Levels in Type 2 Diabetic Patients

Article

Full-text available

Jun 2016
CURR VASC PHARMACOL

Background: Inhibition of dipeptidyl peptidase-4 (DPP-4) has been proposed as a therapeutic target for type 2 diabetes (T2DM). Arterial stiffness, a predictor of future cardiovascular events and all-cause mortality, is augmented in these patients. However, effects of DPP-4 inhibitors on arterial stiffness remain unknown. In this study, we compared effects of anagliptin, an inhibitor of DPP-4 on arterial stiffness evaluated by cardio-ankle vascular index (CAVI) with those of an equipotent glucose-lowering agent, glimepiride in patients with T2DM. Methods: The study involved 50 consecutive outpatients (33 males and 17 females; mean age of 72.5±9.5 years) who visited our hospitals for a risk-screening test or treatment for T2DM. They underwent complete history and physical examination, and determination of blood chemistry and anthropometric variables, and then were randomized to receive either anagliptin (n=26) or glimepiride (n=24) for 6 months. Results: After 6-months treatment, fasting plasma glucose and HbA1c values were comparably reduced in both groups. Anagliptin, but not glimepiride treatment significantly decreased low-density lipoprotein cholesterol, malondialdehydemodified LDL, remnant-like particle (RLP) cholesterol, CAVI, alanine transaminase (ALT), ϒ-glutamyl transferase and visceral fat volume. In multiple regression analysis, absolute changes from baseline of RLP cholesterol and ALT after anagliptin treatment for 6 months (ΔRLP cholesterol and ΔALT) were independently correlated with ΔCAVI (R2=0.445). Conclusion: The present study suggests that anagliptin may exert a beneficial effect on arterial stiffness in patients with T2DM, which is independent of its blood glucose-lowering property. Anagliptin may ameliorate arterial stiffness partly via reduction of RLP cholesterol and improvement of liver function.

In Patients with Coronary Artery Disease and Type 2 Diabetes, SIRT1 Expression in Circulating Mononuclear Cells Is Associated with Levels of Inflammatory Cytokines but Not with Coronary Lesions

Article

Full-text available

Jan 2016
BMRI

While SIRT1 is significantly associated with atherosclerosis and diabetic complications, its relevance to coronary lesions in patients with coronary artery disease and type 2 diabetes has not been specifically investigated. Thus, we assessed SIRT1 expression in peripheral blood mononuclear cells in these patients. We found that SIRT1 expression did not significantly correlate with syntax scores from coronary angiography ( p > 0.05 ). Notably, plasma levels of the inflammatory cytokines tumor necrosis factor- α , monocyte chemoattractant protein-1, and high-sensitivity C-reactive protein were markedly higher in diabetic patients ( p < 0.05 ). In addition, SIRT1 expression was negatively correlated with levels of these cytokines, as well as that of interleukin-6 ( p < 0.05 ). In summary, the data indicate that SIRT1 expression in peripheral blood mononuclear cells is significantly correlated with inflammatory cytokines levels in patients with coronary artery disease and type 2 diabetes but not with the severity of coronary lesions.

Coronary Artery Disease: Why We should Consider the Y Chromosome

Article

Full-text available

Feb 2016
Heart Lung Circ

Coronary artery disease (CAD) is one of the leading causes of morbidity and mortality globally. In the last few years our understanding of the genetic and molecular mechanisms that promote CAD in individuals has increased with the advent of the genome era. This complex inflammatory disease has well-defined environmental risk factors however, in the last 10 years, studies including genome-wide association studies (GWAS) have clearly demonstrated a genetic influence on CAD. Recently, studies on the human Y chromosome have also demonstrated that genetic variation within the male-specific region of the Y chromosome (MSY) could play a part in determining cardiovascular risk in men, confirming the notion that the increased risk for CAD in men cannot be fully explained through common CAD risk factors. Here, we review the literature about the pathophysiology of CAD, its potential causes and environmental risk factors known so far. Furthermore, we review the genetics of CAD, especially the latest discoveries regarding the implication of the Y chromosome, the most underexplored portion of the human genome to date, highlighting methods and difficulties arising in this research field, and discussing the importance of considering the Y chromosome in CAD research.

Taregting acylcarnitine content in vascular tissue to attenuate development of atherosclerosis

Article

Jul 2015
Atherosclerosis

Objective: The elevation of the levels of L-carnitine and its fatty acid esters, acylcarnitines, in tissue or plasma has been linked to the development of atherosclerosis. Recently, a potent inhibitor of L-carnitine biosynthesis and transport, methyl-γ-butyrobetaine (methyl-GBB), was discovered. In this study, we evaluated the effects of γ-butyrobetaine (GBB), L-carnitine and methyl-GBB administration on the progression of atherosclerosis. Methods: Apolipoprotein E knockout (apoE −/−) mice were treated with methyl-GBB, L-carnitine or GBB for 4 months. Following the treatment, the amount of atherosclerotic lesions, the number of immune cells in atheroscle-rotic lesions and the plasma lipid profile were analysed. The L-carnitine and acylcarnitine levels were determined in the aortic tissues of CD-1 outbred mice 2 weeks after treatment with methyl-GBB at the dose of 10 mg/kg. Results: Treatment with methyl-GBB decreased the acylcarnitine and L-carnitine levels in the aortic tissues by seventeen-and tenfold , respectively. Methyl-GBB treatment at a dose of 10 mg/kg reduced the size of atheroscle-rotic plaques by 36%. Neither L-carnitine nor GBB treatment affected the development of atherosclerosis. Conclusions: Methyl-GBB administration significantly attenuated the development of atherosclerosis in apoE −/− mice. Our results demonstrate that decreasing the acylcarnitine pools can attenuate the development of atherosclerosis.

N6-methyladenosine RNA methylation in diabetic kidney disease

Article

Jan 2024

Diabetic nephropathy: Focusing on pathological signals, clinical treatment, and dietary regulation

Article

Mar 2023
BIOMED PHARMACOTHER

Diabetic nephropathy (DN) is one of the most severe complications of diabetes. However, due to its complex pathological mechanisms, no effective therapeutic methods (other than ACEIs and ARBs) have been applied, which have been used for many years in clinical practice. Recent studies have shown that emerging therapeutics, including novel target-based pharmacotherapy, cell therapies, and dietary regulation, are leading to new hopes for DN management. This review aims to shed new light on the treatment of DN by describing the important pathological mechanisms of DN and by analysing recent advances in clinical treatment, including drug therapy, cell therapy, and dietary regulation. In pathological mechanisms, RAAS activation, AGE accumulation, and EMT are involved in inflammation, cellular stress, apoptosis, pyroptosis, and autophagy. In pharmacotherapy, several new therapeutics, including SGLT2 inhibitors, GLP-1 agonists, and MRAs, are receiving public attention. In addition, stem cell therapies and dietary regulation are also being emphasized. Herein, we highlight the importance of combining therapy and dietary regulation in the treatment of DN and anticipate more basic research or clinical trials to verify novel strategies.

Berberine attenuates diabetic atherosclerosis via enhancing the interplay between KLF16 and PPARα in ApoE−/− mice

Article

Jul 2022
BIOCHEM BIOPH RES CO

Cardiovascular disease caused by atherosclerosis is a leading cause of morbidity and mortality worldwide. Diabetes is a major independent risk factor for the development of atherosclerotic cardiovascular diseases. Diabetic atherosclerosis is characterized by hyperglycemia, hyperinsulinemia, and dyslipidemia. These multiple pathological factors can induce oxidative stress, inflammation, and vascular dysfunction, which can initiate and accelerate atherogenesis. Therefore, the strategy to control the development of diabetic atherosclerosis is beneficial to the patients. Berberine is one of the most promising natural products that feature significant beneficial properties on lipid and glucose metabolism, indicating the potential to improve diabetic atherosclerosis. However, the effect and underlying mechanism against diabetic atherosclerosis remain unclear. In this study, HFD and STZ were used to induce diabetic atherosclerosis in apoE−/− mice, which was followed by berberine administration. Subsequently, the degree of atherosclerotic plaque, plaque stability, and lipid and glucose metabolism were determined. In addition, the underlying mechanism was revealed by in vitro and in vivo experiments. We observed that berberine improved the dysfunction of lipid and glucose metabolism, and inhibited vascular inflammation, which reduced atherogenesis and plaque vulnerability. Mechanistically, berberine stimulated KLF16 and PPARα expression in vivo and in vitro, and activation of PPARα by berberine was through enhancing KLF16 expression and nuclear translocation. Collectively, berberine can attenuate diabetic atherosclerosis via enhancing the interplay between KLF16 and PPARα, suggesting that KLF16 is a new target of berberine and enhancing KLF16 by berberine is an efficient strategy for alleviating diabetic atherosclerosis.

Cardiovascular complications of diabetes

Article

Jul 2022

Introduction: Type 2 diabetes mellitus (T2DM) is the ninth leading cause of mortality globally, and the prevalence continues to rise. Among individuals with T2DM, over two-thirds of deaths are caused by the cardiovascular complications of diabetes. These complications include atherosclerosis, coronary artery disease, nephropathy, stroke, thromboembolism, peripheral vascular disease. They have been long studied, and there are several theories as to the pathophysiology of how diabetes leads to these complications. The least understood mechanism is the pathophysiology linking diabetes to heart failure. Areas covered: This review focuses on the mechanisms of how T2DM leads to the aforementioned complications, particularly highlighting the development of heart failure. An extensive literature review of novel therapeutic options targeting the cardiovascular effects of T2DM was completed and summarized in this review. Expert opinion: This review finds that most studies to date have focused on the atherosclerotic vascular complications of diabetes. The pathophysiology between T2DM and heart failure is even less understood. Currently therapies that aim to decrease the risk of heart failure in diabetes are sparse. More research is required in order to better understand the changes at a cellular level and subsequently help providers to choose therapeutics that better target cardiovascular complications.

Epigenetics in the pathogenesis of diabetic nephropathy

Article

Full-text available

Nov 2021

Diabetic nephropathy (DN), which is a common microvascular complication with a high incidence in diabetic patients, greatly increases the mortality of patients. With further study on DN, it is found that epigenetics plays a crucial role in the pathophysiological process of DN. Epigenetics has an important impact on the development of DN through a variety of mechanisms, and promotes the generation and maintenance of metabolic memory, thus ultimately leading to a poor prognosis. In this review we discuss the methylation of DNA, modification of histone, and regulation of non-coding RNA involved in the progress of cell dysfunction, inflammation and fibrosis in the kidney, which ultimately lead to the deterioration of DN.

Prevalence of peripheral arterial disease and associated factors in people with type 2 diabetes

Article

Full-text available

Dec 2021

Introduction: The high rate of diabetes mellitus index (DM), along with the increase in cardiovascular compromise that DM favors, and the scarcity of epidemiological data regarding the prevalence of peripheral arterial disease (PAD) in this population, make it important to study risk factors associated with the development of PAD in the population with type 2 diabetes mellitus (DM2). Objective: To estimate the prevalence of PAD together with the associated factors in a sample of patients with DM2, treated in the Family Health Strategies (FHS) program, in the municipality of Pindamonhangaba, SP. Methods: Quantitative research in a cross-sectional study of 38 individuals who were diagnosed with DM2, between 40 and 77 years old, selected by convenience sampling and treated in the family health program in two different districts of the municipality. The method consisted of the evaluation of personal and anthropometric data, anamnesis and physical examination including the ankle-brachial index (ABI). Results: PAD was present in 21.1% (95%CI: 16.9 to 25.8) of the investigated population. Risk factors observed were age range of 51 to 69 years (75%), overweight (50%), systemic arterial hypertension (SAH) (100%), smoking (62.5%) and physical inactivity (87.5%). Conclusion: The prevalence of PAD was more than a fifth of those diagnosed with DM2, and the most prevalent associated risk factors were SAH, physical inactivity, smoking and overweight with and without PAD.

The roles of immune cells in atherosclerotic calcification

Article

Jul 2021
Vascular

Atherosclerosis is the leading cause of acute cardiovascular events, and vascular calcification is an important pathological phenomenon in atherosclerosis. Recently, many studies have shown that immune cells are closely associated with the development of atherosclerosis and calcification, but there are many conflicting viewpoints because of immune system complications, such as the pro-atherosclerotic and atheroprotective effects of regulatory B cells (Bregs), T helper type 2 (Th2) cells and T helper type 17 (Th17) cells. In this review, we summarize the studies on the roles of immune cells, especially lymphocytes and macrophages, in atherosclerotic calcification. Furthermore, we prepared graphs showing the relationship between T cells, B cells and macrophages and atherosclerotic calcification. Finally, we highlight some potential issues that are closely associated with the function of immune cells in atherosclerotic calcification. Based on current research results, this review summarizes the relationship between immune cells and atherosclerotic calcification, and it will be beneficial to understand the relationship of immune cells and atherosclerotic calcification.

A double‐blind placebo‐controlled clinical trial testing the effect of hyperbaric oxygen therapy on brain and cognitive outcomes of mildly cognitively impaired elderly with type 2 diabetes: Study design

Article

Full-text available

Apr 2020

Introduction: Type 2 diabetes (T2D) is a risk factor for dementia. Ischemia due to vascular pathology is hypothesized to be an underlying mechanism for this association. Hyperbaric oxygen therapy (HBOT) is a treatment in which oxygen-enriched air (up to 100%) is administered to patients in a chamber at a pressure above one atmosphere absolute. HBOT is approved for the treatment of T2D ischemic non-healing wounds. Evidence from animal studies and small clinical trials suggests that HBOT improves hypoxic/ischemic brain injuries, consequently inducing brain angiogensis, leading to cognitive improvement. Methods: We present the design of the first double-blind, placebo-controlled, clinical trial on brain and cognitive outcomes in elderly (n = 154) with T2D and mild cognitive impairment to compare the effects of HBOT versus sham (normal air with 1.1 ATA pressure in the first and last 5 minutes of the session). Eligible candidates are randomized with equal probability to HBOT and sham. Outcomes are assessed before and after treatment, and at 6- and 12-month follow-up. The primary cognitive outcome is global cognitive change, indexed by a composite sum of z-scores of four executive functions and four episodic memory tests. The primary neurobiological outcome is cerebral blood flow (CBF; via arterial spin labeling magnetic resonance imaging [ASL-MRI]) and cerebral glucose utilization via fluorodeoxyglucose positron emission tomography (FDG-PET). Secondary outcome measures are specific cognitive domains (executive function and episodic memory) and functional measures (Clinical Dementia Rating sum of boxes, activities of daily living). Efficacy analyses will be performed for the intent-to-treat sample. Discussion: Recent studies suggest that HBOT induces neuroplasticity and improves cognition in post-stroke and traumatic brain injury patients. However, its effect on cognition, cerebral blood flow, and brain glucose utilization in T2D patients at high dementia risk is yet to be determined. If effective, this study may provide strong evidence for the brain and cognitive benefits of HBOT in this population.

Brain-derived neurotrophic factor alleviates diabetes mellitus-accelerated atherosclerosis by promoting M2 polarization of macrophages through repressing the STAT3 pathway

Article

Feb 2020
CELL SIGNAL

Diabetes mellitus-accelerated atherosclerosis (DMAS) is one of the vascular complications of diabetes. Brain-derived neurotrophic factor (BDNF) plays a critical role in diabetes mellitus. However, the mechanism by which BDNF is involved in DMAS remains unknown. This study investigates the effect of BDNF on the progression of DMAS as well as the underlying mechanism of action. The levels of BDNF in serum and peripheral blood mononuclear cells (PBMCs) from patients with DMAS and health controls were measured as well as the expression of inflammatory cytokines (IL-1β, TNF-α, IL-10, TGF-β and IL-13). The effects of BDNF restoration on cytokine release, macrophage differentiation and the formation of atherosclerotic plaques were evaluated both in vitro and in vivo using the DMAS mouse model. Downregulation of BDNF was identified in the serum and PBMCs of patients with DMAS. Elevation of BDNF contributed to a reduction in the AS lesion area in low-density lipoprotein receptor-/- mice, inactivated the STAT3 pathway, decreased pro-inflammatory cytokines IL-1β and TNF-α, and increased IL-10, TGF-β and IL-13. BDNF overexpression also increased the proportion of M2 macrophages and alleviated atherosclerotic lesions. Our findings demonstrate that BDNF overexpression promotes M2 macrophage polarization, which represses the development of DMAS by inactivating the STAT3 pathway.

Spinal Cord Ischemia in Pancreas Transplantation: The UK Experience

Article

Full-text available

Oct 2019

BACKGROUND: Spinal cord ischemia (SCI) is a rare but devastating condition that can occur in the perioperative period resulting in paraplegia. Although diabetes mellitus is a risk factor for SCI in other types of major surgery, SCI is not widely recognized in transplantation. The aim of this study was to quantify the risk of spinal cord ischemia in pancreatic transplantation. METHODS: All UK pancreas transplant units were surveyed between 2017-2018. The risk of SCI in pancreas transplantation was estimated using the number of radiologically-confirmed cases relative to the number of pancreatic transplants from UK registry data during the same time period. RESULTS: There have been 6 cases of spinal cord ischemia during pancreas transplantation since 2002. No aortic clamping occurred in any recipient. During or after surgery, all patients experienced episodes of hypotension (systolic blood pressure ≤90mmHg) prior to the onset of neurological symptoms. Epoprostenol, epidural anesthesia and postoperative hemodialysis may have contributed to systemic hypotension. The mainstay of early treatment for SCI for all cases was blood pressure control. DISCUSSION: Based on these findings, there is approximately a 1:440 risk of spinal cord ischemia in pancreas transplantation. Hypotension appears to be a prominent risk factor. Strategies for mitigating the risk of spinal cord ischemia are discussed, drawing on evidence from thoraco-abdominal aortic aneurysm surgery. The risk of long-term neurological deficit should be discussed with prospective pancreas recipients given the potential impact on posttransplant quality of life. PMID: 31651791

Matrine pre-treatment suppresses AGEs- induced HCSMCs fibrotic responses by regulating Poldip2/mTOR pathway

Article

Oct 2019
EUR J PHARMACOL

The fibrotic response of vascular smooth muscle cells (VSMCs) takes responsibilities in atherosclerosis. Advanced glycation end products (AGEs) induce and promote the fibrotic responses of VSMCs. Matrine shows potent anti-fibrotic and cardio-protective effects. This study was aimed to investigate the underlying mechanisms of matrine's inhibitory effects on AGEs-induced VSMCs fibrotic responses. Cultured human coronary smooth muscle cells (HCSMCs) were pre-treated with matrine and exposed to AGEs. Specific siRNA was used to silence polymerase delta interacting protein 2 (Poldip2) expression. Sircol collagen assay was used to assess collagen content. Protein expression and phosphorylation levels were determined by Western blotting. Matrine pre-treatment significantly reduced collagen content, increased smooth muscle myosin heavy chain 11 (MYH11) and Poldip2 expression, decreased expressions of collagen I, β1-integrin, phsphoinositide-3-kinase (PI3K) and nuclear phosphorylated p70S6k, and reduced phosphorylation levels of protein kinase B (Akt) and mechanistic target of rapamycin (mTOR) in HCSMCs exposed to AGEs in a concentration dependent manner. Specific siRNA effectively silenced Poldip2 expression and impaired matrine's effect on collagen content, expressions of MYH11, collagen I, β1-integrin, PI3K, nuclear p-p70S6k and phosphorylation levels of Akt and mTOR in HCSMCs exposed to AGEs. Matrine suppresses AGEs- induced fibrotic responses in HCSMCs via regulating Poldip2/mTOR signaling pathway.

Diabetic dyslipidemia and microvascular complications of diabetes

Article

Full-text available

Jan 2018

Diabetic dyslipidemia is one of the main risk factors for atherosclerosis. Although its participation in diabetic microvascular complications is not that dominant, dyslipidemia may play an important role in formation and progression of these complications. Pathophysiological mechanisms by which diabetic dyslipidemia affects the etiopathogenesis of diabetic nephropathy, retinopathy, neuropathy and diabetic foot are presented. The data from clinical studies and treatment possibilities for particular microvascular complications using lipid-lowering therapy are discussed.Key words: diabetes mellitus - diabetic foot - dyslipidemia - nephropathy - neuropathy - retinopathy.

Tissue Oxygenation and Negative-Pressure Wound Therapy When Applied to the Feet of Persons With Diabetes Mellitus: An Observational Study

Article

Nov 2017
J WOUND OSTOMY CONT

Purpose: Our group has reported that negative-pressure wound therapy (NPWT) decreases tissue oxygenation by 84% in the foot of diabetic patients because the pad of the connecting drainage tube and foam sponge of the NPWT system compress the wound bed. The purpose of this study was to determine whether an NPWT modified dressing application reduces tissue oxygenation in the feet of persons with diabetes mellitus. Design: A prospective, clinical, observational study. Subjects and setting: We enrolled 30 patients with diabetic mellitus; their mean age was 63.9 ± 11.2 years (mean ± standard deviation). All were cared for at the diabetic wound center at an academic tertiary medical center in South Korea between 2014 and January 2015. Methods: Transcutaneous partial oxygen pressures (TcpO2) were measured to determine tissue oxygenation levels beneath modified NPWT dressings. A TcpO2 sensor was fixed at the tarsometatarsal area of the contralateral unwounded foot. A negative pressure of -125 mm Hg was applied until TcpO2 reached a plateau state; values were measured before, during, and after the modified NPWT. The Wilcoxon' and Mann-Whitney U tests were used to compare differences between these measurements. Results: TcpO2 levels decreased by 26% during the modified NPWT. Mean TcpO2 values before, during, and after turning off the therapy were 54.3 ± 15.3 mm Hg, 41.6 ± 16.3 mm Hg, and 53.3 ± 15.6 mm Hg (P < .05), respectively. Conclusion: Applying NPWT without the pad of the connecting drainage tube significantly reduces the amount of tissue oxygenation loss beneath foam dressings on the skin of the foot dorsum in diabetic patients.

Diabetic polyneuropathy, deep white matter lesions, and carotid atherosclerosis: is there any association?

Article

Oct 2017

The morphologic and functional damages of diabetes mellitus (DM) on microcirculation can play a role in the pathogenesis of both polyneuropathy and cerebral white matter lesions. The aim of this study is to investigate the relation between polyneuropathy and cerebral deep white matter lesions (DWMLs) and carotid atherosclerosis in patients with type 2 DM. Sixty-six patients with type 2 DM without any disorder that may cause polyneuropathy, and vascular risk factors except for DM and hyperlipidemia were included in the study. DWMLs and carotid atherosclerosis were investigated in patients with and without polyneuropathy. Forty patients (60.6%) had diabetic sensorimotor polyneuropathy. DWMLs were more frequent in patients with polyneuropathy compared to patients without polyneuropathy (p = 0.003). Logistic regression analysis confirmed association between polyneuropathy and DWMLs after adjusted for age (p = 0.013), duration of DM (p = 0.007), and both age and duration of DM (p = 0.016). No statistically significant difference was found between patients with and without polyneuropathy for carotid atherosclerosis. Among patients with polyneuropathy, those having DWMLs had higher mean age (p = 0.003) and longer symptom duration (p = 0.020) compared to patients without DWMLs. No association was found between DWMLs and carotid atherosclerosis. Polyneuropathy and cerebral DWMLs in type 2 DM patients may share common pathogenesis; presence and duration of polyneuropathy symptoms may predict ischemic white matter damage independent of carotid atherosclerosis.

Anti-atherosclerotic effect of hesperidin in LDLr −/− mice and its possible mechanism

Article

Sep 2017
EUR J PHARMACOL

Hesperidin, a citrus bioflavonoid, exerts numerous pharmacological activities. However, its protective effect against atherosclerosis in vivo remains poorly understood. In the present study, we aimed to observe the effects of hesperidin on high fat diet (HFD)-induced atherosclerosis using LDL receptor deficient (LDLr(-/-)) mice. After 12 weeks of treatment, the animals were sacrificed. The blood samples were collected for further analysis. Mouse peritoneal macrophages were collected. Hepatic lipid content, quantification of atherosclerosis, assessment of oxidative stress and inflammation, gene expressions were performed on liver and aorta samples. The data showed that hesperidin ameliorated HFD-induced weight gain, improved insulin resistance and ameliorated hyperlipidemia. Hesperidin suppressed HFD-induced hepatic steatosis, atherosclerotic plaque area and macrophage foam cell formation. Further study showed that hesperidin down-regulated expressions of acetyl coenzyme A carboxylase alpha (ACCα) and fatty acid synthase (FAS) which are two key enzymes in fatty acid and triglyceride synthesis in liver; and upregulated expression of hepatic ATP-binding cassette transporters G8 (ABCG8), macrophage ATP-binding cassette transporters A1 (ABCA1) and G1 (ABCG1) which are transporters involved in the process of reverse cholesterol transport. Hesperidin also reduced oxidative stress by normalizing activities of antioxidant enzymes and inflammation in HFD-fed LDLr(-/-) mice. These findings suggest that hesperidin reduced atherosclerosis via its pleiotropic effects, including improvement of insulin resistance, amelioration of lipid profiles, inhibition of macrophage foam cell formation, anti-oxidative effect and anti-inflammatory action.

Diabetes for Cardiologists: Practical Issues in Diagnosis and Management

Article

Jul 2016

Diabetes mellitus (DM), a chronic metabolic disease characterized by hyperglycemia, is a profound cardiovascular (CV) risk factor. It compounds the effects of all other risk factors, leads to premature micro- and macro-vascular disease, facilitates development of heart failure, worsens the clinical course of all CV diseases and shortens life expectancy. Established DM, unrecognized DM, and dysglycemia that may progress to DM are all commonly present at the time of presentation of overt CV disease. Thus, CV specialists and trainees are frequently treating patients with dysglycemia. The traditional and proven role of cardiologists in reducing the risk of macrovascular events in this population is through aggressive lipid and blood pressure treatment. But a more proactive role in the detection and management of DM is likely to become increasingly important as the prevalence continues to increase and as therapies continue to improve. The latter include antihyperglycemic therapies with proven cardiovascular safety profiles and CV event reduction properties not yet fully elucidated and not necessarily related to glycemic control. Accordingly, the purpose of this paper is to: a) expand the interest of cardiologists in earlier stages of the natural history of DM when prevention or early detection might help achieve greatest benefit; b) highlight principles of optimal glycemic management with an emphasis on add-on choices showing promising CV event reductions and lacking CV adverse effects; and c) encourage cardiologists to become proactive partners in the multidisciplinary care needed to ensure optimal, lifelong vascular health of patients with or at risk of DM.

Methyl-γ-butyrobetaine decreases levels of acylcarnitines and attenuates the development of atherosclerosis

Article

May 2015

The elevation of the levels of L-carnitine and its fatty acid esters, acylcarnitines, in tissue or plasma has been linked to the development of atherosclerosis. Recently, a potent inhibitor of L-carnitine biosynthesis and transport, methyl-γ-butyrobetaine (methyl-GBB), was discovered. In this study, we evaluated the effects of γ-butyrobetaine (GBB), L-carnitine and methyl-GBB administration on the progression of atherosclerosis. Apolipoprotein E knockout (apoE-/-) mice were treated with methyl-GBB, L-carnitine or GBB for 4 months. Following the treatment, the amount of atherosclerotic lesions, the number of immune cells in atherosclerotic lesions and the plasma lipid profile were analysed. The L-carnitine and acylcarnitine levels were determined in the aortic tissues of CD-1 outbred mice 2 weeks after treatment with methyl-GBB at the dose of 10 mg/kg. Treatment with methyl-GBB decreased the acylcarnitine and L-carnitine levels in the aortic tissues by seventeen- and ten-fold, respectively. Methyl-GBB treatment at a dose of 10 mg/kg reduced the size of atherosclerotic plaques by 36%. Neither L-carnitine nor GBB treatment affected the development of atherosclerosis. Methyl-GBB administration significantly attenuated the development of atherosclerosis in apoE-/- mice. Our results demonstrate that decreasing the acylcarnitine pools can attenuate the development of atherosclerosis. Copyright © 2015. Published by Elsevier Inc.

Clinical influence of early follow-up glycosylated hemoglobin levels on cardiovascular outcomes in diabetic patients with ST-segment elevation myocardial infarction after coronary reperfusion

Article

Apr 2015

Recent studies have shown continuous control of diabetes is important for favorable outcomes in patients with ST-segment elevation myocardial infarction (STEMI). This study aimed to evaluate the clinical influence of postprocedural glycosylated hemoglobin A1c (HbA1c) levels on major adverse cardiac events (MACE) in diabetic patients with STEMI after coronary reperfusion. A total of 303 patients with diabetes and STEMI undergoing a primary percutaneous coronary intervention were enrolled in this study. All eligible patients were divided into the following three groups on the basis of follow-up HbA1c (FU-HbA1c) levels, which were measured at a median of 85 days after the procedure: optimal, FU-HbA1c<7%; suboptimal, 7%≤FU-HbA1c<9%; and poor, FU-HbA1c≥9%. We analyzed the 12-month cumulative MACE, defined as mortality, nonfatal myocardial infarction, and revascularization. In addition, we investigated FU-HbA1c levels as a predictor of MACE. The incidence rates of MACE differed significantly between groups (6.4 vs. 13.6 vs. 19.6%; P=0.048). Moreover, the risk was increased in each successive group (hazard ratio: 1.00 vs. 2.19 vs. 3.68; P=0.046). Each 1% increase in the FU-HbA1c level posed a 49.3% relative increased risk of MACE (hazard ratio: 1.266; P=0.031). The cut-off value for the match of FU-HbA1c levels and MACE was 7.45%. This study showed that higher levels of early FU-HbA1c after reperfusion in diabetic patients with STEMI were associated with increased 12-month MACE, suggesting continuous serum glucose level control even after reperfusion is important for a better outcome. FU-HbA1c seems to be a useful marker for predicting clinical outcome.

The Projection of Prevalence and Cost of Diabetes in Canada: 2000 to 2016

Article

Full-text available

Jun 2004

OBJECTIVE: The objective of this study was to project the prevalence and cost of diabetes mellitus in Canada and its provinces for the years 2000 to 2016. METHOD: The total costs per capita, including hospitalizations, day procedures, physician services, prescription drugs and estimated outpatient dialysis services, for individuals with diabetes were measured using 1996 administrative data from Saskatchewan Health, Saskatchewan, Canada, and organized within 5-year age groups. The general population projection was based on the Statistics Canada provincial median population projections from 2000 to 2016. Diabetes incidence, prevalence and mortality projections for this time period were obtained from previous projection estimates for Manitoba, Canada. RESULTS: The number of individuals with diabetes in the general population in Canada will increase from approximately 1.4 milhon patients in 2000 to 2.4 million patients in 2016. The total healthcare costs are projected to increase from Can $4.66 billion in 2000 to S8.14 billion in 2016 (1996 dollar values). Important differences in diabetes-related cost trends were noted across provinces and territories. CONCLUSION: The projection model used in this study showed that if the increase in the prevalence of diabetes follows current trends, healthcare costs for people with diabetes in Canada will increase by 75% between 2000 and 2016.

Effects of ramipril on cardiovascular and microvascular outcomes in people with diabetes mellitus: Results of the HOPE study and MICRO-HOPE substudy

Article

Full-text available

Jan 2000
LANCET

Summary Background Diabetes mellitus is a strong risk factor for cardiovascular and renal disease. We investigated whether the angiotensin-converting-enzyme (ACE) inhibitor ramipril can lower these risks in patients with diabetes. Methods 3577 people with diabetes included in the Heart Outcomes Prevention Evaluation study, aged 55 years or older, who had a previous cardiovascular event or at least one other cardiovascular risk factor, no clinical proteinuria, heart failure, or low ejection fraction, and who were not taking ACE inhibitors, were randomly assigned ramipril (10 mg/day) or placebo, and vitamin E or placebo, according to a two-by-two factorial design. The combined primary outcome was myocardial infarction, stroke, or cardiovascular death. Overt nephropathy was a main outcome in a substudy. Findings The study was stopped 6 months early (after 4·5 years) by the independent data safety and monitoring board because of a consistent benefit of ramipril compared with placebo. Ramipril lowered the risk of the combined primary outcome by 25% (95% CI 12-36, p=0·0004), myocardial infarction by 22% (6-36), stroke by 33% (10-50), cardiovascular death by 37% (21-51), total mortality by 24% (8-37), revascularisation by 17% (2-30), and overt nephropathy by 24% (3-40, p=0·027). After adjustment for the changes in systolic (2·4 mm Hg) and diastolic (1·0 mm Hg) blood pressures, ramipril still lowered the risk of the combined primary outcome by 25% (12-36, p=0·0004). Interpretation Ramipril was beneficial for cardiovascular events and overt nephropathy in people with diabetes. The cardiovascular benefit was greater than that attributable to the decrease in blood pressure. This treatment represents a vasculoprotective and renoprotective effect for people with diabetes.

Major Lipids, Apolipoproteins, and Risk of Vascular Disease

Article

Full-text available

Nov 2009

Context Associations of major lipids and apolipoproteins with the risk of vascular disease have not been reliably quantified. Objective To assess major lipids and apolipoproteins in vascular risk. Design, Setting, and Participants Individual records were supplied on 302 430 people without initial vascular disease from 68 long-term prospective studies, mostly in Europe and North America. During 2.79 million person-years of follow-up, there were 8857 nonfatal myocardial infarctions, 3928 coronary heart disease [CHD] deaths, 2534 ischemic strokes, 513 hemorrhagic strokes, and 2536 unclassified strokes. Main Outcome Measures Hazard ratios (HRs), adjusted for several conventional factors, were calculated for 1-SD higher values: 0.52 loge triglyceride, 15 mg/dL high-density lipoprotein cholesterol (HDL-C), 43 mg/dL non–HDL-C, 29 mg/dL apolipoprotein AI, 29 mg/dL apolipoprotein B, and 33 mg/dL directly measured low-density lipoprotein cholesterol (LDL-C). Within-study regression analyses were adjusted for within-person variation and combined using meta-analysis. Results The rates of CHD per 1000 person-years in the bottom and top thirds of baseline lipid distributions, respectively, were 2.6 and 6.2 with triglyceride, 6.4 and 2.4 with HDL-C, and 2.3 and 6.7 with non–HDL-C. Adjusted HRs for CHD were 0.99 (95% CI, 0.94-1.05) with triglyceride, 0.78 (95% CI, 0.74-0.82) with HDL-C, and 1.50 (95% CI, 1.39-1.61) with non–HDL-C. Hazard ratios were at least as strong in participants who did not fast as in those who did. The HR for CHD was 0.35 (95% CI, 0.30-0.42) with a combination of 80 mg/dL lower non–HDL-C and 15 mg/dL higher HDL-C. For the subset with apolipoproteins or directly measured LDL-C, HRs were 1.50 (95% CI, 1.38-1.62) with the ratio non–HDL-C/HDL-C, 1.49 (95% CI, 1.39-1.60) with the ratio apo B/apo AI, 1.42 (95% CI, 1.06-1.91) with non–HDL-C, and 1.38 (95% CI, 1.09-1.73) with directly measured LDL-C. Hazard ratios for ischemic stroke were 1.02 (95% CI, 0.94-1.11) with triglyceride, 0.93 (95% CI, 0.84-1.02) with HDL-C, and 1.12 (95% CI, 1.04-1.20) with non–HDL-C. Conclusion Lipid assessment in vascular disease can be simplified by measurement of either total and HDL cholesterol levels or apolipoproteins without the need to fast and without regard to triglyceride.

New Insights in to ER stress induced insulin resistance

Article

Full-text available

Jul 2012

Insulin resistance is a major characteristic of obesity and type 2 diabetes (T2DM). During the last decade, endoplasmic reticulum (ER) stress has emerged as a new player in this field and a considerable number of recent studies have pointed out its role in the onset of insulin resistance (IR). ER stress appears to act directly as a negative modulator of the insulin signaling pathway but also indirectly by promoting lipid accumulation. This review aims to summarize and decipher the abundant new literature concerning the emerging and multifaceted involvement of ER stress in the development of metabolic dysfunctions in insulin target tissues.

Hyperglycemic Ins2AkitaLdlr-/- mice show severely elevated lipid levels and increased atherosclerosis: A model of type 1 diabetic macrovascular disease

Article

Full-text available

May 2011

Accelerated atherosclerosis is the leading cause of death in type 1 diabetes, but the mechanism of type 1 diabetes-accelerated atherosclerosis is not well understood, in part due to the lack of a good animal model for the long-term studies required. In an attempt to create a model for studying diabetic macrovascular disease, we have generated type 1 diabetic Akita mice lacking the low density lipoprotein receptor (Ins2(Akita)Ldlr⁻/⁻). Ins2(Akita)Ldlr⁻/⁻ mice were severely hyperglycemic with impaired glucose tolerance. Compared with Ldlr⁻/⁻ mice, 20-week-old Ins2(Akita)Ldlr⁻/⁻ mice fed a 0.02% cholesterol AIN76a diet showed increased plasma triglyceride and cholesterol levels, and increased aortic root cross-sectional atherosclerotic lesion area [224% (P < 0.001) in males and 30% (P < 0.05) in females]. Microarray and quantitative PCR analyses of livers from Ins2(Akita)Ldlr⁻/⁻ mice revealed altered expression of lipid homeostatic genes, including sterol-regulatory element binding protein (Srebp)1, liver X receptor (Lxr)α, Abca1, Cyp7b1, Cyp27a1, and Lpl, along with increased expression of pro-inflammatory cytokine genes, including interleukin (Il)1α, Il1β, Il2, tumor necrosis factor (Tnf)α, and Mcp1. Immunofluorescence staining showed that the expression levels of Mcp1, Tnfα, and Il1β were also increased in the atherosclerotic lesions and artery walls of Ins2(Akita)Ldlr⁻/⁻ mice. Thus, the Ins2(Akita)Ldlr⁻/⁻ mouse appears to be a promising model for mechanistic studies of type 1 diabetes-accelerated atherosclerosis.

Diabetes mellitus, fasting blood glucose concentration, and risk of vascular disease: A collaborative meta-analysis of 102 prospective studies

Article

Full-text available

Jun 2010
LANCET

Uncertainties persist about the magnitude of associations of diabetes mellitus and fasting glucose concentration with risk of coronary heart disease and major stroke subtypes. We aimed to quantify these associations for a wide range of circumstances. We undertook a meta-analysis of individual records of diabetes, fasting blood glucose concentration, and other risk factors in people without initial vascular disease from studies in the Emerging Risk Factors Collaboration. We combined within-study regressions that were adjusted for age, sex, smoking, systolic blood pressure, and body-mass index to calculate hazard ratios (HRs) for vascular disease. Analyses included data for 698 782 people (52 765 non-fatal or fatal vascular outcomes; 8.49 million person-years at risk) from 102 prospective studies. Adjusted HRs with diabetes were: 2.00 (95% CI 1.83-2.19) for coronary heart disease; 2.27 (1.95-2.65) for ischaemic stroke; 1.56 (1.19-2.05) for haemorrhagic stroke; 1.84 (1.59-2.13) for unclassified stroke; and 1.73 (1.51-1.98) for the aggregate of other vascular deaths. HRs did not change appreciably after further adjustment for lipid, inflammatory, or renal markers. HRs for coronary heart disease were higher in women than in men, at 40-59 years than at 70 years and older, and with fatal than with non-fatal disease. At an adult population-wide prevalence of 10%, diabetes was estimated to account for 11% (10-12%) of vascular deaths. Fasting blood glucose concentration was non-linearly related to vascular risk, with no significant associations between 3.90 mmol/L and 5.59 mmol/L. Compared with fasting blood glucose concentrations of 3.90-5.59 mmol/L, HRs for coronary heart disease were: 1.07 (0.97-1.18) for lower than 3.90 mmol/L; 1.11 (1.04-1.18) for 5.60-6.09 mmol/L; and 1.17 (1.08-1.26) for 6.10-6.99 mmol/L. In people without a history of diabetes, information about fasting blood glucose concentration or impaired fasting glucose status did not significantly improve metrics of vascular disease prediction when added to information about several conventional risk factors. Diabetes confers about a two-fold excess risk for a wide range of vascular diseases, independently from other conventional risk factors. In people without diabetes, fasting blood glucose concentration is modestly and non-linearly associated with risk of vascular disease. British Heart Foundation, UK Medical Research Council, and Pfizer.

Glycated Hemoglobin, Diabetes, and Cardiovascular Risk in Nondiabetic Adults

Article

Full-text available

May 2010
NEW ENGL J MED

Loss of Insulin Signaling in Vascular Endothelial Cells Accelerates Atherosclerosis in Apolipoprotein E Null Mice

Article

Full-text available

May 2010

To determine whether insulin action on endothelial cells promotes or protects against atherosclerosis, we generated apolipoprotein E null mice in which the insulin receptor gene was intact or conditionally deleted in vascular endothelial cells. Insulin sensitivity, glucose tolerance, plasma lipids, and blood pressure were not different between the two groups, but atherosclerotic lesion size was more than 2-fold higher in mice lacking endothelial insulin signaling. Endothelium-dependent vasodilation was impaired and endothelial cell VCAM-1 expression was increased in these animals. Adhesion of mononuclear cells to endothelium in vivo was increased 4-fold compared with controls but reduced to below control values by a VCAM-1-blocking antibody. These results provide definitive evidence that loss of insulin signaling in endothelium, in the absence of competing systemic risk factors, accelerates atherosclerosis. Therefore, improving insulin sensitivity in the endothelium of patients with insulin resistance or type 2 diabetes may prevent cardiovascular complications.

Insulin resistance, lipotoxicity, type 2 diabetes and atherosclerosis: The missing links. The Claude Bernard Lecture 2009

Article

Full-text available

Apr 2010
DIABETOLOGIA

Ralph Defronzo

Insulin resistance is a hallmark of type 2 diabetes mellitus and is associated with a metabolic and cardiovascular cluster of disorders (dyslipidaemia, hypertension, obesity [especially visceral], glucose intolerance, endothelial dysfunction), each of which is an independent risk factor for cardiovascular disease (CVD). Multiple prospective studies have documented an association between insulin resistance and accelerated CVD in patients with type 2 diabetes, as well as in non-diabetic individuals. The molecular causes of insulin resistance, i.e. impaired insulin signalling through the phosphoinositol-3 kinase pathway with intact signalling through the mitogen-activated protein kinase pathway, are responsible for the impairment in insulin-stimulated glucose metabolism and contribute to the accelerated rate of CVD in type 2 diabetes patients. The current epidemic of diabetes is being driven by the obesity epidemic, which represents a state of tissue fat overload. Accumulation of toxic lipid metabolites (fatty acyl CoA, diacylglycerol, ceramide) in muscle, liver, adipocytes, beta cells and arterial tissues contributes to insulin resistance, beta cell dysfunction and accelerated atherosclerosis, respectively, in type 2 diabetes. Treatment with thiazolidinediones mobilises fat out of tissues, leading to enhanced insulin sensitivity, improved beta cell function and decreased atherogenesis. Insulin resistance and lipotoxicity represent the missing links (beyond the classical cardiovascular risk factors) that help explain the accelerated rate of CVD in type 2 diabetic patients.

Intensive glucose control and macrovascular outcomes in type 2 diabetes [published correction appears in Diabetologia. 2009;52:2470]

Article

Full-text available

Sep 2009
DIABETOLOGIA

Improved glucose control in type 2 diabetes is known to reduce the risk of microvascular events. There is, however, continuing uncertainty about its impact on macrovascular disease. The aim of these analyses was to generate more precise estimates of the effects of more-intensive, compared with less-intensive, glucose control on the risk of major cardiovascular events amongst patients with type 2 diabetes. A prospectively planned group-level meta-analysis in which characteristics of trials to be included, outcomes of interest, analyses and subgroup definitions were all pre-specified. A total of 27,049 participants and 2,370 major vascular events contributed to the meta-analyses. Allocation to more-intensive, compared with less-intensive, glucose control reduced the risk of major cardiovascular events by 9% (HR 0.91, 95% CI 0.84-0.99), primarily because of a 15% reduced risk of myocardial infarction (HR 0.85, 95% CI 0.76-0.94). Mortality was not decreased, with non-significant HRs of 1.04 for all-cause mortality (95% CI 0.90-1.20) and 1.10 for cardiovascular death (95% CI 0.84-1.42). Intensively treated participants had significantly more major hypoglycaemic events (HR 2.48, 95% CI 1.91-3.21). Exploratory subgroup analyses suggested the possibility of a differential effect for major cardiovascular events in participants with and without macrovascular disease (HR 1.00, 95% CI 0.89-1.13, vs HR 0.84, 95% CI 0.74-0.94, respectively; interaction p = 0.04). Targeting more-intensive glucose lowering modestly reduced major macrovascular events and increased major hypoglycaemia over 4.4 years in persons with type 2 diabetes. The analyses suggest that glucose-lowering regimens should be tailored to the individual.

Mechanisms and consequences of macrophage apoptosis in atherosclerosis

Article

Full-text available

Nov 2008

Macrophage apoptosis is an important feature of atherosclerotic plaque development. Research directed at understanding the functional consequences of macrophage death in atherosclerosis has revealed opposing roles for apoptosis in atherosclerotic plaque progression. In early lesions, macrophage apoptosis limits lesion cellularity and suppresses plaque progression. In advanced lesions, macrophages apoptosis promotes the development of the necrotic core, a key factor in rendering plaques vulnerable to disruption and in acute lumenal thrombosis. The first section of this review will examine the role of phagocytic clearance of apoptotic macrophages, a process known as efferocytosis, in the dichotomous roles of macrophage apoptosis in early vs. advanced lesions. The second section will focus on the molecular and cellular mechanisms that are thought to govern macrophage death during atherosclerosis. Of particular interest is the complex and coordinated role that the endoplasmic reticulum (ER) stress pathway and pattern recognition receptors (PRRs) may play in triggering macrophage apoptosis.

Molecular Identity and Cellular Distribution of Advanced Glycation Endproduct Receptors: Relationship of p60 to OST-48 and p90 to 80K-H Membrane Proteins

Article

Full-text available

Nov 1996

Advanced glycation endproducts (AGEs) are derivatives of nonenzymatic reactions between sugars and protein or lipids, and together with AGE-specific receptors are involved in numerous pathogenic processes associated with aging and hyperglycemia. Two of the known AGE-binding proteins isolated from rat liver membranes, p60 and p90, have been partially sequenced. We now report that the N-terminal sequence of p60 exhibits 95% identity to OST-48, a 48-kDa member of the oligosaccharyltransferase complex found in microsomal membranes, while sequence analysis of p90 revealed 73% and 85% identity to the N-terminal and internal sequences, respectively, of human 80K-H, a 80- to 87-kDa protein substrate for protein kinase C. AGE-ligand and Western analyses of purified oligosaccharyltransferase complex, enriched rough endoplasmic reticulum, smooth endoplasmic reticulum, and plasma membranes from rat liver or RAW 264.7 macrophages yielded a single protein of approximately 50 kDa recognized by both anti-p60 and anti-OST-48 antibodies, and also exhibited AGE-specific binding. Immunoprecipitated OST-48 from rat rough endoplasmic reticulum fractions exhibited both AGE binding and immunoreactivity to an anti-p60 antibody. Immune IgG raised to recombinant OST-48 and 80K-H inhibited binding of AGE-bovine serum albumin to cell membranes in a dose-dependent manner. Immunostaining and flow cytometry demonstrated the surface expression of OST-48 and 80K-H on numerous cell types and tissues, including mononuclear, endothelial, renal, and brain neuronal and glial cells. We conclude that the AGE receptor components p60 and p90 are identical to OST-48, and 80K-H, respectively, and that they together contribute to the processing of AGEs from extra- and intracellular compartments and in the cellular responses associated with these pathogenic substances.

Lander HM, Tauras JM, Ogiste JS, Hori O, Moss RA, Schmidt AMActivation of the receptor for advanced glycation end products triggers a p21(ras)-dependent mitogen-activated protein kinase pathway regulated by oxidant stress. J Biol Chem 272:17810-17814

Article

Full-text available

Aug 1997

Advanced glycation end products (AGEs) exert their cellular effects on cells by interacting with specific cellular receptors, the best characterized of which is the receptor for AGE (RAGE). The transductional processes by which RAGE ligation transmits signals to the nuclei of cells is unknown and was investigated. AGE-albumin, a prototypic ligand, activated p21ras in rat pulmonary artery smooth muscle cells that express RAGE, whereas nonglycated albumin was without effect. MAP kinase activity was enhanced at concentrations of AGE-albumin, which activated p21ras and NF-κB. Depletion of intracellular glutathione rendered cells more sensitive to AGE-mediated activation of this signaling pathway. In contrast, signaling was blocked by preventing p21ras from associating with the plasma membrane or mutating Cys118 on p21ras to Ser. Signaling was receptor-dependent, because it was prevented by blocking access to RAGE with either anti-RAGE IgG or by excess soluble RAGE. These data suggest that RAGE-mediated induction of cellular oxidant stress triggers a cascade of intracellular signals involving p21ras and MAP kinase, culminating in transcription factor activation. The molecular mechanism that triggers this pathway likely involves oxidant modification and activation of p21ras.

Mortality from Coronary Heart Disease in Subjects with Type 2 Diabetes and in Nondiabetic Subjects with and without Prior Myocardial Infarction

Article

Full-text available

Jul 1998

Type 2 (non-insulin-dependent) diabetes is associated with a marked increase in the risk of coronary heart disease. It has been debated whether patients with diabetes who have not had myocardial infarctions should be treated as aggressively for cardiovascular risk factors as patients who have had myocardial infarctions. To address this issue, we compared the seven-year incidence of myocardial infarction (fatal and nonfatal) among 1373 nondiabetic subjects with the incidence among 1059 diabetic subjects, all from a Finnish population-based study. The seven-year incidence rates of myocardial infarction in nondiabetic subjects with and without prior myocardial infarction at base line were 18.8 percent and 3.5 percent, respectively (P<0.001). The seven-year incidence rates of myocardial infarction in diabetic subjects with and without prior myocardial infarction at base line were 45.0 percent and 20.2 percent, respectively (P<0.001). The hazard ratio for death from coronary heart disease for diabetic subjects without prior myocardial infarction as compared with nondiabetic subjects with prior myocardial infarction was not significantly different from 1.0 (hazard ratio, 1.4; 95 percent confidence interval, 0.7 to 2.6) after adjustment for age and sex, suggesting similar risks of infarction in the two groups. After further adjustment for total cholesterol, hypertension, and smoking, this hazard ratio remained close to 1.0 (hazard ratio, 1.2; 95 percent confidence interval, 0.6 to 2.4). Our data suggest that diabetic patients without previous myocardial infarction have as high a risk of myocardial infarction as nondiabetic patients with previous myocardial infarction. These data provide a rationale for treating cardiovascular risk factors in diabetic patients as aggressively as in nondiabetic patients with prior myocardial infarction.

Cardiovascular risk factors clustering with endogenous hyperinsulinaemia predict death from coronary heart disease patients with Type II diabetes

Article

Full-text available

Feb 2000

Information on the association of hyperinsulinaemia with coronary heart disease (CHD) in patients with Type II (non-insulin-dependent) diabetes is limited and controversial. Therefore, we carried out a prospective study to examine the predictive value of fasting plasma insulin and "hyperinsulinaemia cluster" with regard to the risk of CHD mortality. At baseline risk factors for CHD were determined in 902 patients aged 45 to 64 years with Type II diabetes not treated by insulin (499 men and 403 women). These patients were followed up to 7 years for CHD mortality. Coronary heart disease mortality (16.2% in men, 9.2% in women) increased significantly in men with increasing plasma insulin tertiles (p = 0.006) and in both sexes combined (p = 0.010) but not in women (p = 0.090). The predictive value of hyperinsulinaemia with regard to death from CHD was independent of conventional cardiovascular risk factors but not of risk factors clustering with hyperinsulinaemia. By applying factor analysis and principal component analysis we showed that "hyperinsulinaemia cluster" (a factor having high positive loadings for body mass index, triglycerides and insulin; and a high negative loading for high-density lipoprotein cholesterol) was predictive of death from CHD in patients with Type II diabetes (hazard ratio with 95% confidence intervals 1.43 (1.18, 1.73), p < 0.001). Our results support the notion that cardiovascular risk factors clustering with endogenous hyperinsulinaemia increase the risk of death from CHD in patients with Type II diabetes not treated with insulin.

A major role for VCAM-1, but not ICAM-1, in early atherosclerosis

Article

Full-text available

Jun 2001

VCAM-1 and ICAM-1 are endothelial adhesion molecules of the Ig gene superfamily that may participate in atherogenesis by promoting monocyte accumulation in the arterial intima. Both are expressed in regions predisposed to atherosclerosis and at the periphery of established lesions, while ICAM-1 is also expressed more broadly. To evaluate functions of VCAM-1 in chronic disease, we disrupted its fourth Ig domain, producing the murine Vcam1(D4D) allele. VCAM-1(D4D) mRNA and protein were reduced to 2-8% of wild-type allele (Vcam1(+)) levels but were sufficient to partially rescue the lethal phenotype of VCAM-1-null embryos. After crossing into the LDL receptor-null background, Vcam1(+/+) and Vcam1(D4D/D4D) paired littermates were generated from heterozygous intercrosses and fed a cholesterol-enriched diet for 8 weeks. The area of early atherosclerotic lesions in the aorta, quantified by en face oil red O staining, was reduced significantly in Vcam1(D4D/D4D) mice, although cholesterol levels, lipoprotein profiles, and numbers of circulating leukocytes were comparable to wild-type. In contrast, deficiency of ICAM-1 either alone or in combination with VCAM-1 deficiency did not alter nascent lesion formation. Therefore, although expression of both VCAM-1 and ICAM-1 is upregulated in atherosclerotic lesions, our data indicate that VCAM-1 plays a dominant role in the initiation of atherosclerosis.

Role of vasa vasorum in transendothelial solute transport in the coronary vessel wall: A study with cryostatic micro-CT

Article

Full-text available

Dec 2004

Using cryostatic microscopic computed tomography (micro-CT), we sought to determine the role of coronary vasa vasorum (VV) in transendothelial solute transport in arteries with normal and increased permeability due to high plasma cholesterol levels. In 6-mo-old pigs on a normal (n=23) and 2% high cholesterol (HC) diet (n=8), 2-cm segments of the proximal left anterior descending coronary arteries were removed in vivo after a selective injection of X-ray contrast solution. Harvesting of the specimens occurred at 0, 15, 25, 35, or 45 s after completion of the contrast injection. Specimens were snap frozen and scanned in our cryostatic micro-CT. The spatial distribution of contrast in the coronary artery wall was quantified using the CT images. Right coronary arteries were infused with Microfil to determine VV density (VV/mm2) and the cumulative lumen surface area (mm2/mm3). Transendothelial diffusion of contrast into the coronary vessel wall is a dynamic process starting at both the subintima and the adventitia. The subintimal opacification moves as a wave toward the adventitia, whereas the adventitial wave resolves. The coronary vessel wall in animals on a HC diet shows higher opacification than in normal coronary arteries without an increase of VV total luminal surface area. The loss of endothelial integrity in hypercholesterolemia significantly alters VV solute washin to, and washout from, the coronary artery wall.

Cholesterol-induced macrophage apoptosis requires ER stress pathways and engagement of the type A scavenger receptor

Article

Full-text available

Nov 2005

Macrophage death in advanced atherosclerosis promotes necrosis and plaque destabilization. A likely cause of macrophage death is accumulation of free cholesterol (FC) in the ER, leading to activation of the unfolded protein response (UPR) and C/EBP homologous protein (CHOP)-induced apoptosis. Here we show that p38 MAPK signaling is necessary for CHOP induction and apoptosis. Additionally, two other signaling pathways must cooperate with p38-CHOP to effect apoptosis. One involves the type A scavenger receptor (SRA). As evidence, FC loading by non-SRA mechanisms activates p38 and CHOP, but not apoptosis unless the SRA is engaged. The other pathway involves c-Jun NH2-terminal kinase (JNK)2, which is activated by cholesterol trafficking to the ER, but is independent of CHOP. Thus, FC-induced apoptosis requires cholesterol trafficking to the ER, which triggers p38-CHOP and JNK2, and engagement of the SRA. These findings have important implications for understanding how the UPR, MAPKs, and the SRA might conspire to cause macrophage death, lesional necrosis, and plaque destabilization in advanced atherosclerotic lesions.

Intensive diabetes treatment and cardiovascular disease in type 1 diabetes in the DCCT/EDIC Study

Article

Full-text available

Jan 2006
NEW ENGL J MED

Intensive diabetes therapy aimed at achieving near normoglycemia reduces the risk of microvascular and neurologic complications of type 1 diabetes. We studied whether the use of intensive therapy as compared with conventional therapy during the Diabetes Control and Complications Trial (DCCT) affected the long-term incidence of cardiovascular disease. The DCCT randomly assigned 1441 patients with type 1 diabetes to intensive or conventional therapy, treating them for a mean of 6.5 years between 1983 and 1993. Ninety-three percent were subsequently followed until February 1, 2005, during the observational Epidemiology of Diabetes Interventions and Complications study. Cardiovascular disease (defined as nonfatal myocardial infarction, stroke, death from cardiovascular disease, confirmed angina, or the need for coronary-artery revascularization) was assessed with standardized measures and classified by an independent committee. During the mean 17 years of follow-up, 46 cardiovascular disease events occurred in 31 patients who had received intensive treatment in the DCCT, as compared with 98 events in 52 patients who had received conventional treatment. Intensive treatment reduced the risk of any cardiovascular disease event by 42 percent (95 percent confidence interval, 9 to 63 percent; P=0.02) and the risk of nonfatal myocardial infarction, stroke, or death from cardiovascular disease by 57 percent (95 percent confidence interval, 12 to 79 percent; P=0.02). The decrease in glycosylated hemoglobin values during the DCCT was significantly associated with most of the positive effects of intensive treatment on the risk of cardiovascular disease. Microalbuminuria and albuminuria were associated with a significant increase in the risk of cardiovascular disease, but differences between treatment groups remained significant (P< or =0.05) after adjusting for these factors. Intensive diabetes therapy has long-term beneficial effects on the risk of cardiovascular disease in patients with type 1 diabetes.

Glucosamine-Induced Endoplasmic Reticulum Dysfunction Is Associated With Accelerated Atherosclerosis in a Hyperglycemic Mouse Model

Article

Full-text available

Feb 2006
DIABETES

Diabetes is a major independent risk factor for cardiovascular disease and stroke; however, the molecular and cellular mechanisms by which diabetes contributes to the development of vascular disease are not fully understood. Our previous studies demonstrated that endoplasmic reticulum (ER) stress-inducing agents, including homocysteine, promote lipid accumulation and activate inflammatory pathways-the hallmark features of atherosclerosis. We hypothesize that the accumulation of intracellular glucosamine observed in diabetes may also promote atherogenesis via a mechanism that involves ER stress. In support of this theory, we demonstrate that glucosamine can induce ER stress in cell types relevant to the development of atherosclerosis, including human aortic smooth muscle cells, monocytes, and hepatocytes. Furthermore, we show that glucosamine-induced ER stress dysregulates lipid metabolism, leading to the accumulation of cholesterol in cultured cells. To examine the relevance of the ER stress pathway in vivo, we used a streptozotocin-induced hyperglycemic apolipoprotein E-deficient mouse model of atherosclerosis. Using molecular biological and histological techniques, we show that hyperglycemia is associated with tissue-specific ER stress, hepatic steatosis, and accelerated atherosclerosis. This novel mechanism may not only explain how diabetes and hyperglycemia promote atherosclerosis, but also provide a potential new target for therapeutic intervention.

From acute ER stress to physiological roles of the Unfolded Protein Response

Article

Full-text available

Apr 2006
CELL DEATH DIFFER

When protein folding in the endoplasmic reticulum (ER) is disrupted by alterations in homeostasis in the ER lumen, eucaryotic cells activate a series of signal transduction cascades that are collectively termed the unfolded protein response (UPR). Here we summarize our current understanding of how the UPR functions upon acute and severe stress. We discuss the mechanism of UPR receptor activation, UPR signal transduction to translational and transcriptional responses, UPR termination, and UPR signals that activate upon irreversible damage. Further, we review recent studies that have revealed that UPR provides a wide spectrum of physiological roles. Each individual UPR subpathway provides a unique and specialized role in diverse developmental and metabolic processes. This is especially observed for professional secretory cells, such as plasma cells, pancreatic beta cells, hepatocytes, and osteoblasts, where high-level secretory protein synthesis requires a highly evolved mechanism to properly fold, process, and secrete proteins. There is a growing body of data that suggest that different subpathways of the UPR are required throughout the entire life of eucaryotic organisms, from regulation of differentiation to induction of apoptosis.

Intensive glucose control and macrovascular outcomes in type 2 diabetes

Article

Nov 2009

The CONTROL Group

Diabetes Mellitus, Fasting Glucose, and Risk of Cause-Specific Death

Article

Jan 2011
Year Bk Med

S. Schinner

Antioxidant vitamins and the risk of carotid atherosclerosis

Article

Dec 2001
J AM COLL CARDIOL

OBJECTIVES This study examined whether dietary intake or plasma levels of antioxidant vitamins were independently associated with common carotid artery intima-media (wall) thickness (IMT) or focal plaque, or both, in a large, randomly selected community population.BACKGROUND Oxidation of low-density lipoprotein (LDL) cholesterol is thought to be important in early atherogenesis. Antioxidant micronutrients may therefore protect against lipid peroxidation and atherosclerotic vascular disease.METHODS We studied 1,111 subjects (558 men and 553 women; age 52 ± 13 years [mean ± SD], range 27 to 77). We measured dietary vitamin intake and fasting plasma levels of vitamins A, C and E, lycopene and alpha- and beta-carotene and performed bilateral carotid artery B-mode ultrasound imaging.RESULTSAfter adjustment for age and conventional risk factors, there was a progressive decrease in mean IMT, with increasing quartiles of dietary vitamin E intake in men (p = 0.02) and a nonsignificant trend in women (p = 0.10). Dietary vitamin E levels accounted for 1% of the variance in measured IMT in men. For plasma antioxidant vitamins, there was an inverse association between carotid artery mean IMT and plasma lycopene in women (p = 0.047), but not in men. None of the other dietary or plasma antioxidant vitamins, nor antioxidant vitamin supplements, were associated with carotid artery IMT or focal carotid artery plaque.CONCLUSIONS This study provides limited support for the hypothesis that increased dietary intake of vitamin E and increased plasma lycopene may decrease the risk of atherosclerosis. No benefit was demonstrated for supplemental antioxidant vitamin use.

Hyperglycaemia is associated with impaired vasa vasorum neovascularization and accelerated atherosclerosis in apolipoprotein-E deficient mice

Article

Jan 2013

Objective: A direct correlation between blood glucose levels and the microvascular complications of diabetes is well established. However, the effects of hyperglycaemia on the vasa vasorum, a microvascular network which surrounds and supplies the walls of large arteries, is not known. The objective of this study is to investigate the effects of hyperglycaemia on the vasa vasorum and to examine correlations between these effects and the development of atherosclerosis in a mouse model. Methods: The micro- and macrovascular effects of hyperglycaemia were examined in streptozotocin-injected apolipoprotein-E deficient (ApoE(-/-)) mice. Retina and aortic sinus were isolated from hyperglycaemic mice and normoglycaemic controls at 5-20 weeks of age. Retinal and vasa vasorum microvessel densities were quantified and correlated to atherosclerotic lesion development. The expression levels of pro-angiogenic factors including vascular endothelial growth factor (VEGF) and VEGF receptor 2 were examined. Results: In normoglycaemic ApoE(-/-) mice atherogenesis is associated with vasa vasorum expansion, which likely corresponds to the increasing blood supply demands of the thickening artery wall. In hyperglycaemic ApoE(-/-) mice there is no significant neovascularization of the vasa vasorum, despite the fact that lesions are significantly larger. This defect may result from a localized deficiency in VEGF. Conclusions: These findings are the first evidence that hyperglycaemia alters the structure of the vasa vasorum. Such microvascular changes directly correlate, and may contribute to, the development and progression of atherosclerosis in hyperglycaemic ApoE-deficient mice.

Protein Kinase C- Contributes to Impaired Endothelial Insulin Signaling in Humans With Diabetes Mellitus

Article

Nov 2012
CIRCULATION

Background: Abnormal endothelial function promotes atherosclerotic vascular disease in diabetes. Experimental studies indicate that disruption of endothelial insulin signaling, through the activity of protein kinase C-β (PKCβ) and nuclear factor κB, reduces nitric oxide availability. We sought to establish whether similar mechanisms operate in the endothelium in human diabetes mellitus. Methods and results: We measured protein expression and insulin response in freshly isolated endothelial cells from patients with type 2 diabetes mellitus (n=40) and nondiabetic controls (n=36). Unexpectedly, we observed 1.7-fold higher basal endothelial nitric oxide synthase (eNOS) phosphorylation at serine 1177 in patients with diabetes mellitus (P=0.007) without a difference in total eNOS expression. Insulin stimulation increased eNOS phosphorylation in nondiabetic subjects but not in diabetic patients (P=0.003), consistent with endothelial insulin resistance. Nitrotyrosine levels were higher in diabetic patients, indicating endothelial oxidative stress. PKCβ expression was higher in diabetic patients and was associated with lower flow-mediated dilation (r=-0.541, P=0.02). Inhibition of PKCβ with LY379196 reduced basal eNOS phosphorylation and improved insulin-mediated eNOS activation in patients with diabetes mellitus. Endothelial nuclear factor κB activation was higher in diabetes mellitus and was reduced with PKCβ inhibition. Conclusions: We provide evidence for the presence of altered eNOS activation, reduced insulin action, and inflammatory activation in the endothelium of patients with diabetes mellitus. Our findings implicate PKCβ activity in endothelial insulin resistance.

Leptin treatment inhibits the progression of atherosclerosis by attenuating hypercholesterolemia in type 1 diabetic Ins2(+/Akita):apoE(-/-) mice

Article

Oct 2012

Aims: The impact of leptin deficiency and its replacement in T1D remain unclear in the context of dyslipidemia and atherosclerosis. The current study has investigated the physiologic role of leptin in lipid metabolism and atherosclerosis in T1D. Methods and results: The present study has employed Ins2(+/Akita):apoE(-/-) mouse model that spontaneously develops T1D, hypercholesterolemia, and atherosclerosis. At age 13 weeks, diabetic Ins2(+/Akita):apoE(-/-) mice showed leptin deficiency by ~92% compared with nondiabetic Ins2(+/+):apoE(-/-) mice. From 13 weeks to 25 weeks of age, diabetic Ins2(+/Akita):apoE(-/-) mice were treated with low-dose leptin (at 0.4 μg/g body weight daily). Leptin treatment diminished food intake by 22-27% in diabetic mice without affecting body weight and lean mass throughout the experiment. Importantly, leptin therapy substantially reduced plasma cholesterol concentrations by ~41%, especially in LDL fractions, in diabetic Ins2(+/Akita):apoE(-/-) mice. Moreover, leptin therapy decreased atherosclerotic lesion in diabetic mice by ~62% comparable to that seen in nondiabetic mice. In addition, leptin restored repressed expression of hepatic sortilin-1, a receptor for LDL clearance, and reversed altered expression of several hepatic genes involved in lipogenesis and cholesterol synthesis characteristic of diabetic mice. These findings were accompanied by normalization of reduced hepatic expression of Irs1 and Irs2 mRNA as well as their protein levels, and improved hepatic insulin-receptor signaling. Conclusions: The present findings suggest that leptin administration may be useful to improve dyslipidemia and reduce atherosclerosis-related cardiovascular disease in human subjects with T1D.

Accelerated Atherosclerosis in Apoe(-/-) Mice Heterozygous for the Insulin Receptor and the Insulin Receptor Substrate-1

Article

Dec 2011
ARTERIOSCL THROM VAS

Prediabetic states are associated with accelerated atherosclerosis, but the availability of mouse models to study connections between these diseases has been limited. The aim of this study was to test the selective role of impaired insulin receptor/insulin receptor substrate-1 signaling on atherogenesis. To address the effects of impaired insulin signaling associated with hyperinsulinemia on atherosclerosis in the absence of obesity and hyperglycemia, we generated insulin receptor (Insr)/insulin receptor substrate-1 (Insr1) double heterozygous apolipoprotein (Apoe)-knockout mice (Insr(+/-)Irs1(+/-)Apoe(-/-)) mice. Insr(+/-)Irs1(+/-)Apoe(-/-) mice fed a Western diet for 15 weeks showed elevated levels of fasting insulin compared to Insr(+/+)Irs1(+/+)Apoe(-/-) mice. There were no significant differences in glucose, triglyceride, HDL, VLDL, cholesterol levels or free fatty acid in the plasma of Insr(+/-)Irs1(+/-)Apoe(-/-) and Insr(+/+)Irs1(+/+)Apoe(-/-) mice. Atherosclerotic lesions were increased in male (brachiocephalic artery) and female (aortic tree) Insr(+/-)Irs1(+/-)Apoe(-/-) compared to Insr(+/+)Irs1(+/+)Apoe(-/-) mice. Bone marrow transfer experiments demonstrated that nonhematopoietic cells have to be Insr(+/-)Irs1(+/-) to accelerate atherosclerosis. Impaired insulin signaling resulted in decreased levels of vascular phospho-eNOS, attenuated endothelium-dependent vasorelaxation and elevated VCAM-1 expression in aortas of Insr(+/-)Irs1(+/-)Apoe(-/-) mice. In addition, phospho-ERK and vascular smooth muscle cell proliferation were significantly elevated in aortas of Insr(+/-)Irs1(+/-)Apoe(-/-) mice. These results demonstrate that defective insulin signaling is involved in accelerated atherosclerosis in Insr(+/-)Irs1(+/-)Apoe(-/-) mice by promoting vascular dysfunction and inflammation.

Endoplasmic Reticulum Stress and Glycogen Synthase Kinase-3 Activation in Apolipoprotein E-Deficient Mouse Models of Accelerated Atherosclerosis

Article

Jan 2012
ARTERIOSCL THROM VAS

The goal of this study was to examine the role of endoplasmic reticulum (ER) stress signaling and the contribution of glycogen synthase kinase (GSK)-3β activation in hyperglycemic, hyperhomocysteinemic, and high-fat-fed apolipoprotein E-deficient (apoE(-/-)) mouse models of accelerated atherosclerosis. Female apoE(-/-) mice received multiple low-dose injections of streptozotocin (40 μg/kg) to induce hyperglycemia, methionine-supplemented drinking water (0.5% wt/vol) to induce hyperhomocysteinemia, or a high-fat (21% milk fat+0.2% cholesterol) diet to induce relative dyslipidemia. A subset of mice from each group was supplemented with sodium valproate (625 mg/kg), a compound with GSK3 inhibitory activity. At 15 and 24 weeks of age, markers of ER stress, lipid accumulation, GSK3β phosphorylation, and GSK3β activity were analyzed in liver and aorta. Atherosclerotic lesions were examined and quantified. Hyperglycemia, hyperhomocysteinemia, and high-fat diet significantly enhanced GSK3β activity and also increased hepatic steatosis and atherosclerotic lesion volume compared with controls. Valproate supplementation blocked GSK3β activation and attenuated the development of atherosclerosis and the accumulation of hepatic lipids in each of the models examined. The mechanism by which GSK3β activity is regulated in these models likely involves alterations in phosphorylation at serine 9 and tyrosine 216. These findings support the existence of a common mechanism of accelerated atherosclerosis involving ER stress signaling through activation of GSK3β. Furthermore, our results suggest that atherosclerosis can be attenuated by modulating GSK3β phosphorylation.

Glucosamine-supplementation promotes endoplasmic reticulum stress, hepatic steatosis and accelerated atherogenesis in apoE−/− mice

Article

Jul 2011

To determine the effects of glucosamine-supplementation on endoplasmic reticulum (ER) stress levels and atherogenesis, and to investigate the potential role of glucosamine in hyperglycemia-associated accelerated atherosclerosis. Five week old apolipoprotein E-deficient (apoE-/-) mice were provided with normal drinking water or water supplemented with 5% glucosamine (w/v) or 5% mannitol (w/v). To induce hyperglycemia, a separate group of apoE-/- mice received multiple low dose injections of streptozotocin (STZ). All mice were provided with a standard chow diet and were euthanized at 15 weeks of age. Hepatic and vascular ER stress levels and atherosclerotic lesion area at the aortic root were determined. STZ-induced hyperglycemic and glucosamine-supplemented mice had significantly larger and more advanced atherosclerotic lesions than control mice. Indications of ER stress were increased in the livers and atherosclerotic lesions of hyperglycemic and glucosamine-supplemented mice but not in the controls. In glucosamine-supplemented mice accelerated atherosclerosis was independent of detectable changes in blood glucose concentration, glucose tolerance, plasma insulin, or plasma lipid levels. Similar to hyperglycemia, glucosamine-supplementation promotes ER stress, hepatic steatosis and accelerated atherosclerosis. These findings support a model by which hyperglycemia promotes hepatic and vascular complications via a glucosamine intermediate.

National, regional, and global trends in fasting plasma glucose and diabetes prevalence since 1980: Systematic analysis of health examination surveys and epidemiological studies with 370 country-years and 2·7 million participants

Article

Jun 2011
LANCET

Data for trends in glycaemia and diabetes prevalence are needed to understand the effects of diet and lifestyle within populations, assess the performance of interventions, and plan health services. No consistent and comparable global analysis of trends has been done. We estimated trends and their uncertainties in mean fasting plasma glucose (FPG) and diabetes prevalence for adults aged 25 years and older in 199 countries and territories. We obtained data from health examination surveys and epidemiological studies (370 country-years and 2·7 million participants). We converted systematically between different glycaemic metrics. For each sex, we used a Bayesian hierarchical model to estimate mean FPG and its uncertainty by age, country, and year, accounting for whether a study was nationally, subnationally, or community representative. In 2008, global age-standardised mean FPG was 5·50 mmol/L (95% uncertainty interval 5·37-5·63) for men and 5·42 mmol/L (5·29-5·54) for women, having risen by 0·07 mmol/L and 0·09 mmol/L per decade, respectively. Age-standardised adult diabetes prevalence was 9·8% (8·6-11·2) in men and 9·2% (8·0-10·5) in women in 2008, up from 8·3% (6·5-10·4) and 7·5% (5·8-9·6) in 1980. The number of people with diabetes increased from 153 (127-182) million in 1980, to 347 (314-382) million in 2008. We recorded almost no change in mean FPG in east and southeast Asia and central and eastern Europe. Oceania had the largest rise, and the highest mean FPG (6·09 mmol/L, 5·73-6·49 for men; 6·08 mmol/L, 5·72-6·46 for women) and diabetes prevalence (15·5%, 11·6-20·1 for men; and 15·9%, 12·1-20·5 for women) in 2008. Mean FPG and diabetes prevalence in 2008 were also high in south Asia, Latin America and the Caribbean, and central Asia, north Africa, and the Middle East. Mean FPG in 2008 was lowest in sub-Saharan Africa, east and southeast Asia, and high-income Asia-Pacific. In high-income subregions, western Europe had the smallest rise, 0·07 mmol/L per decade for men and 0·03 mmol/L per decade for women; North America had the largest rise, 0·18 mmol/L per decade for men and 0·14 mmol/L per decade for women. Glycaemia and diabetes are rising globally, driven both by population growth and ageing and by increasing age-specific prevalences. Effective preventive interventions are needed, and health systems should prepare to detect and manage diabetes and its sequelae. Bill & Melinda Gates Foundation and WHO.

Diabetes Mellitus, Fasting Glucose, and Risk of Cause-Specific Death

Article

Mar 2011
NEW ENGL J MED

The extent to which diabetes mellitus or hyperglycemia is related to risk of death from cancer or other nonvascular conditions is uncertain. We calculated hazard ratios for cause-specific death, according to baseline diabetes status or fasting glucose level, from individual-participant data on 123,205 deaths among 820,900 people in 97 prospective studies. After adjustment for age, sex, smoking status, and body-mass index, hazard ratios among persons with diabetes as compared with persons without diabetes were as follows: 1.80 (95% confidence interval [CI], 1.71 to 1.90) for death from any cause, 1.25 (95% CI, 1.19 to 1.31) for death from cancer, 2.32 (95% CI, 2.11 to 2.56) for death from vascular causes, and 1.73 (95% CI, 1.62 to 1.85) for death from other causes. Diabetes (vs. no diabetes) was moderately associated with death from cancers of the liver, pancreas, ovary, colorectum, lung, bladder, and breast. Aside from cancer and vascular disease, diabetes (vs. no diabetes) was also associated with death from renal disease, liver disease, pneumonia and other infectious diseases, mental disorders, nonhepatic digestive diseases, external causes, intentional self-harm, nervous-system disorders, and chronic obstructive pulmonary disease. Hazard ratios were appreciably reduced after further adjustment for glycemia measures, but not after adjustment for systolic blood pressure, lipid levels, inflammation or renal markers. Fasting glucose levels exceeding 100 mg per deciliter (5.6 mmol per liter), but not levels of 70 to 100 mg per deciliter (3.9 to 5.6 mmol per liter), were associated with death. A 50-year-old with diabetes died, on average, 6 years earlier than a counterpart without diabetes, with about 40% of the difference in survival attributable to excess nonvascular deaths. In addition to vascular disease, diabetes is associated with substantial premature death from several cancers, infectious diseases, external causes, intentional self-harm, and degenerative disorders, independent of several major risk factors. (Funded by the British Heart Foundation and others.).

Loss of Canonical Insulin Signaling Accelerates Vascular Smooth Muscle Cell Proliferation and Migration Through Changes in p27(Kip1) Regulation

Article

Feb 2011
ENDOCRINOLOGY

Insulin resistance is associated with an accelerated rate of atherosclerosis. Vascular smooth muscle cell (VSMC) migration and proliferation are important components of atherosclerosis. To elucidate the effects of the loss of normal insulin receptor (IR) signaling on VSMC function, we compared the proliferation and migration of murine VSMCs lacking the IR (L2-VSMCs) with wild type (WT-VSMCs). We also examined changes in the response of L2-VSMCs to insulin stimulation and to inhibition of the mammalian target of rapamycin (mTOR), a kinase critical in VSMC proliferation and migration. The L2-VSMCs exhibit greater proliferation and migration rates compared with WT-VSMCs. L2-VSMCs also exhibit a resistance to the effects of rapamycin, an mTOR inhibitor, on proliferation, migration, and cell cycle progression. The resistance to mTOR inhibition is coupled with a loss of effect on the cyclin-dependent kinase inhibitor p27(Kip1), an inhibitor of cell cycle progression and VSMC migration. In response to stimulation with physiological insulin, the L2-VSMCs exhibit a loss of Akt phosphorylation and a significantly increased activation of the ERK-1/2 compared with WT-VSMCs. Insulin stimulation also decreased p27(Kip1) mRNA in L2-VSMCs but not in WT-VSMCs. The effect of insulin on p27(Kip1) mRNA was blocked by pretreatment with an ERK-1/2 pathway inhibitor. We conclude that loss of canonical insulin signaling results in increased ERK-1/2 activation in response to physiological insulin that decreases p27(Kip1) mRNA. These data demonstrate a potential mechanism where changes in IR signaling could lead to a decrease in p27(Kip1), accelerating VSMC proliferation and migration.

Vascular Lesions due to Obstruction of the Vasa Vasorum

Article

Dec 1966

The Role of Endoplasmic Reticulum Stress in the Progression of Atherosclerosis

Article

Oct 2010
CIRC RES

Ira Tabas

Prolonged activation of the endoplasmic reticulum (ER) stress pathway known as the unfolded protein response (UPR) can lead to cell pathology and subsequent tissue dysfunction. There is now ample evidence that the UPR is chronically activated in atherosclerotic lesional cells, particularly advanced lesional macrophages and endothelial cells. The stressors in advanced lesions that can lead to prolonged activation of the UPR include oxidative stress, oxysterols, and high levels of intracellular cholesterol and saturated fatty acids. Importantly, these arterial wall stressors may be especially prominent in the settings of obesity, insulin resistance, and diabetes, all of which promote the clinical progression of atherosclerosis. In the case of macrophages, prolonged ER stress triggers apoptosis, which in turn leads to plaque necrosis if the apoptotic cells are not rapidly cleared. ER stress-induced endothelial cell apoptosis may also contribute to plaque progression. Another potentially important proatherogenic effect of prolonged ER stress is activation of inflammatory pathways in macrophages and, perhaps in response to atheroprone shear stress, endothelial cells. Although exciting work over the last decade has begun to shed light on the mechanisms and in vivo relevance of ER stress-driven atherosclerosis, much more work is needed to fully understand this area and to enable an informed approach to therapeutic translation.

Age-specific relevance of usual blood pressure to vascular mortality a meta-analysis of individual data for one million adults in 61 prospective studies Prospective Studies Collaboration Lancet 2002 360 9343

Article

Jan 2002

The age-specific relevance of blood pressure to cause-specific mortality is best assessed by collaborative meta-analysis of individual participant data from the separate prospective studies. Methods Information was obtained on each of one million adults with no previous vascular disease recorded at baseline in 61 prospective observational studies of blood pressure and mortality. During 12.7 million person-years at risk, there were about 56 000 vascular deaths (12 000 stroke, 34000 ischaemic heart disease [IHD], 10000 other vascular) and 66 000 other deaths at ages 40-89 years. Meta-analyses, involving "time-dependent" correction for regression dilution, related mortality during each decade of age at death to the estimated usual blood pressure at the start of that decade. Findings Within each decade of age at death, the proportional difference in the risk of vascular death associated with a given absolute difference in usual blood pressure is about the same down to at least 115 mm Hg usual systolic blood pressure (SBP) and 75 mm Hg usual diastolic blood pressure (DBP), below which there is little evidence. At ages 40-69 years, each difference of 20 mm Hg usual SBP (or, approximately equivalently, 10 mm Hg usual DBP) is associated with more than a twofold difference in the stroke death rate, and with twofold differences in the death rates from IHD and from other vascular causes. All of these proportional differences in vascular mortality are about half as extreme at ages 80-89 years as at,ages 40-49 years, but the annual absolute differences in risk are greater in old age. The age-specific associations are similar for men and women, and for cerebral haemorrhage and cerebral ischaemia. For predicting vascular mortality from a single blood pressure measurement, the average of SBP and DBP is slightly more informative than either alone, and pulse pressure is much less informative. Interpretation Throughout middle and old age, usual blood pressure is strongly and directly related to vascular (and overall) mortality, without any evidence of a threshold down to at least 115/75 mm Hg.

Glycated Hemoglobin, Diabetes, and Cardiovascular Risk in Nondiabetic Adults

Article

Mar 2010
NEW ENGL J MED

Fasting glucose is the standard measure used to diagnose diabetes in the United States. Recently, glycated hemoglobin was also recommended for this purpose. We compared the prognostic value of glycated hemoglobin and fasting glucose for identifying adults at risk for diabetes or cardiovascular disease. We measured glycated hemoglobin in whole-blood samples from 11,092 black or white adults who did not have a history of diabetes or cardiovascular disease and who attended the second visit (occurring in the 1990-1992 period) of the Atherosclerosis Risk in Communities (ARIC) study. The glycated hemoglobin value at baseline was associated with newly diagnosed diabetes and cardiovascular outcomes. For glycated hemoglobin values of less than 5.0%, 5.0 to less than 5.5%, 5.5 to less than 6.0%, 6.0 to less than 6.5%, and 6.5% or greater, the multivariable-adjusted hazard ratios (with 95% confidence intervals) for diagnosed diabetes were 0.52 (0.40 to 0.69), 1.00 (reference), 1.86 (1.67 to 2.08), 4.48 (3.92 to 5.13), and 16.47 (14.22 to 19.08), respectively. For coronary heart disease, the hazard ratios were 0.96 (0.74 to 1.24), 1.00 (reference), 1.23 (1.07 to 1.41), 1.78 (1.48 to 2.15), and 1.95 (1.53 to 2.48), respectively. The hazard ratios for stroke were similar. In contrast, glycated hemoglobin and death from any cause were found to have a J-shaped association curve. All these associations remained significant after adjustment for the baseline fasting glucose level. The association between the fasting glucose levels and the risk of cardiovascular disease or death from any cause was not significant in models with adjustment for all covariates as well as glycated hemoglobin. For coronary heart disease, measures of risk discrimination showed significant improvement when glycated hemoglobin was added to models including fasting glucose. In this community-based population of nondiabetic adults, glycated hemoglobin was similarly associated with a risk of diabetes and more strongly associated with risks of cardiovascular disease and death from any cause as compared with fasting glucose. These data add to the evidence supporting the use of glycated hemoglobin as a diagnostic test for diabetes.

Macrophage heterogeneity in atherosclerotic plaques

Article

Nov 2009
CURR OPIN LIPIDOL

The varied behaviour of macrophages and foam cells during atherosclerosis and its clinical sequelae prompt the question whether all these activities can be the property of a single cell population. Subsets of monocytes with distinct patterns of surface markers and behaviours during inflammation have recently been characterized and shown to have complementary roles during progression of atherosclerosis. A variety of macrophage phenotypes derived from these monocyte subsets in response to mediators of innate and acquired immunity have also been found in plaques. Based on functional properties and genomic signatures, they may have different impacts on facets of plaque development, including fibrous cap and lipid core formation. Monocyte and macrophage phenotypic diversity is important in atherogenesis. More work is needed to define consistent marker sets for the different foam cell phenotypes in experimental animals and humans. Cell tracking studies are needed to establish their relationship with monocyte subtypes. In addition, genetic and pharmacological manipulation of phenotypes will be useful to define their functions and exploit the resulting therapeutic potential.

Evidence Supporting a Role for Endoplasmic Reticulum Stress in the Development of Atherosclerosis in a Hyperglycaemic Mouse Model

Article

Jun 2009
ANTIOXID REDOX SIGN

We previously observed a correlation between elevated levels of vascular endoplasmic reticulum (ER) stress and accelerated atherosclerotic plaque development in chronically hyperglycemic apolipoprotein-deficient (ApoE(-/-)) mice. We hypothesize that ER stress plays a causative role in diabetic atherogenesis. Here we examine the temporal relation between the onset of hyperglycemia, glucosamine accumulation in the vessel wall, ER stress, and the development of atherosclerosis. We demonstrate, by using streptozotocin-induced hyperglycemic ApoE(-/-) mice, that conditions of hyperglycemia increase intracellular glucosamine levels and endothelial ER stress levels in the endothelium before the onset of atherosclerosis. At 15 weeks of age, hyperglycemic mice have significantly larger atherosclerotic lesions (0.120 +/- 0.023 vs. 0.065 +/- 0.021 mm2; p = 0.001) relative to normoglycemic mice. Significantly, hyperglycemia-associated accelerated atherosclerosis is observed before the onset of dyslipidemias, suggesting that leveled glucose is sufficient to promote atherogenesis independently. Diagnostic markers of elevated ER-stress levels are increased in macrophage-derived foam cells in early and advanced atherosclerotic lesions. Dietary supplementation with valproate, a small branched-chain fatty acid that interferes with ER-stress signaling, significantly attenuates accelerated atherogenesis in this model. Together, these data are consistent with a causative role for hyperglycemia-associated ER stress in the development and progression of diabetic atherosclerosis.

Low Vasa Vasorum Densities Correlate with Inflammation and Subintimal Thickening – Potential Role in Location-Determination of Atherogenesis

Article

Apr 2009

To assess the role of coronary vasa vasorum (VV) spatial distribution in determining the location of early atherosclerotic lesion development. Six, 3-month-old, female, crossbred swine were fed 2% high-cholesterol (HC) diet for 3 months prior to euthanasia. Six other pigs were fed normal diet (N) for the entire 6 months. Right coronary arteries were harvested and scanned intact with micro-CT (20mum cubic-voxel-size). After scanning, randomly selected cross-sectional histological sections were stained for nuclear-factor kappaB (NF-kappaB), hypoxia-inducible factor-1alpha (HIF-1alpha), macrophages, von-Willebrand-factor, dihydroethidium (DHE), tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). The number of positive stained cells, as well as intima-to-media ratio, were compared with VV density (#/mm(2)) obtained from micro-CT images (which closely matched the location of the histological sections) in each of four equal quadrants of the coronary vessel wall. In normal, as well as HC pigs, the number of NF-kappaB (r=0.73 and 0.70), HIF-1alpha (r=0.74 and 0.77), TNF-alpha (r=0.58 and 0.72) and IL-6 (r=0.70 and 0.72) positive cells as well as the expression of DHE (Kendall tau coefficient -0.64 and -0.63) inversely correlated with VV density. In HC the VV density also inversely correlated with intima/media ratios (r=0.65). Our data suggest that low VV density territories within the coronary vessel wall are susceptible to hypoxia, oxidative stress and microinflammation and may therefore be starting points of early atherogenesis.

Role of vasa vasorum in nourishment of the aortic wall

Article

Jun 1981
Am J Physiol

Vasa vasorum are present in the middle and outer layers of media in the thoracic aorta of dogs and humans. To examine the role of vasa vasorum in nourishment of the aorta, we ligated four contiguous pairs of intercostal arteries in anesthetized dogs. These arteries are the source of vasa to the descending aorta but not the aortic arch. Blood flow through vasa vasorum was measured with microspheres. Acute intercostal ligation did not reduce conductance in the aortic arch but reduced conductance in the middle third of the descending aorta from 7 +/- 1 to 3 +/- 0.7 (SE) ml.min-1.100 g-1.mmHg-1 (P less than 0.05). After intercostal ligation, infusion of adenosine (5 mumol.kg-1.min-1 iv) increased conductance in the aortic arch 3- to 4-fold but did not increase conductance in the descending aorta. Six to ten days after intercostal ligation, conductance in the middle third of the descending aorta remained low. Vasodilator capacity was partially restored in outer layers of the descending aorta, probably by collateral vessels or formation of new vessels. Morphological changes ranged from broad bands of necrosis to patchy areas of cell loss, primarily in middle layers of descending aorta. We conclude that vasa vasorum are critical in nourishment of aortic media.

Antibacterial activity of lysozyme and lactoferrin is inhibited by binding of advanced glycation-modified proteins to a conserved motif

Article

Nov 1995

Why diabetes is associated with abnormally high susceptibility to infection remains unknown, although two major antibacterial proteins, lysozyme and lactoferrin, have now been shown to specifically bind glucose-modified proteins bearing advanced glycation end products (AGEs). Exposure to AGE-modified proteins inhibits the enzymatic and bactericidal activity of lysozyme, and blocks the bacterial agglutination and bacterial killing activities of lactoferrin. Peptide mapping revealed a single AGE binding domain in lysozyme and two AGE binding domains in lactoferrin; each domain contains a 17- to 18- amino acid cysteine-bounded loop motif (CX15-16C) that is markedly hydrophilic. Synthetic peptides corresponding to these motifs in lysozyme and lactoferrin exhibited AGE binding activity, and similar domains are also present in other antimicrobial proteins. These results suggest that elevated levels of AGEs in tissues and serum of diabetic patients may inhibit endogenous antibacterial proteins by binding to this conserved AGE-binding cysteine-bounded domain 'ABCD' motif, thereby increasing susceptibility to bacterial infections in the diabetic population.

Suppression of accelerated diabetic atherosclerosis by the soluble receptor for advanced glycation endproducts

Article

Oct 1998

Accelerated atherosclerosis in patients with diabetes is a major cause of their morbidity and mortality, and it is unresponsive to therapy aimed at restoring relative euglycemia. In hyperglycemia, nonenzymatic glycation and oxidation of proteins and lipids results in the accumulation of irreversibly formed advanced glycation endproducts. These advanced glycation endproducts engage their receptor in cells of the blood vessel wall, thereby activating mechanisms linked to the development of vascular lesions. We report here a model of accelerated and advanced atherosclerosis in diabetic mice deficient for apolipoprotein E. Treatment of these mice with the soluble extracellular domain of the receptor for advanced glycation endproducts completely suppressed diabetic atherosclerosis in a glycemia- and lipid-independent manner. These findings indicate interaction between the advanced glycation endproducts and their receptor is involved in the development of accelerated atherosclerosis in diabetes, and identify this receptor as a new therapeutic target in diabetic macrovascular disease.

Effects of Ramipril and Vitamin E on Atherosclerosis : The Study to Evaluate Carotid Ultrasound Changes in Patients Treated With Ramipril and Vitamin E (SECURE)

Article

Mar 2001
CIRCULATION

Activation of the renin-angiotensin-aldosterone system and oxidative modification of LDL cholesterol play important roles in atherosclerosis. The Study to Evaluate Carotid Ultrasound changes in patients treated with Ramipril and vitamin E (SECURE), a substudy of the Heart Outcomes Prevention Evaluation (HOPE) trial, was a prospective, double-blind, 3x2 factorial design trial that evaluated the effects of long-term treatment with the angiotensin-converting enzyme inhibitor ramipril and vitamin E on atherosclerosis progression in high-risk patients. A total of 732 patients >/=55 years of age who had vascular disease or diabetes and at least one other risk factor and who did not have heart failure or a low left ventricular ejection fraction were randomly assigned to receive ramipril 2.5 mg/d or 10 mg/d and vitamin E (RRR-alpha-tocopheryl acetate) 400 IU/d or their matching placebos. Average follow-up was 4.5 years. Atherosclerosis progression was evaluated by B-mode carotid ultrasound. The progression slope of the mean maximum carotid intimal medial thickness was 0.0217 mm/year in the placebo group, 0.0180 mm/year in the ramipril 2.5 mg/d group, and 0.0137 mm/year in the ramipril 10 mg/d group (P=0.033). There were no differences in atherosclerosis progression rates between patients on vitamin E and those on placebo. Long-term treatment with ramipril had a beneficial effect on atherosclerosis progression. Vitamin E had a neutral effect on atherosclerosis progression.

Antioxidant vitamins and the risk of carotid atherosclerosis. The Perth Carotid Ultrasound Disease Assessment Study (CUDAS)

Article

May 2002
J AM COLL CARDIOL

This study examined whether dietary intake or plasma levels of antioxidant vitamins were independently associated with common carotid artery intima-media (wall) thickness (IMT) or focal plaque, or both, in a large, randomly selected community population. Oxidation of low-density lipoprotein (LDL) cholesterol is thought to be important in early atherogenesis. Antioxidant micronutrients may therefore protect against lipid peroxidation and atherosclerotic vascular disease. We studied 1,111 subjects (558 men and 553 women; age 52 +/- 13 years [mean +/- SD], range 27 to 77). We measured dietary vitamin intake and fasting plasma levels of vitamins A, C and E, lycopene and alpha- and beta-carotene and performed bilateral carotid artery B-mode ultrasound imaging. RESULTS; After adjustment for age and conventional risk factors, there was a progressive decrease in mean IMT, with increasing quartiles of dietary vitamin E intake in men (p = 0.02) and a nonsignificant trend in women (p = 0.10). Dietary vitamin E levels accounted for 1% of the variance in measured IMT in men. For plasma antioxidant vitamins, there was an inverse association between carotid artery mean IMT and plasma lycopene in women (p = 0.047), but not in men. None of the other dietary or plasma antioxidant vitamins, nor antioxidant vitamin supplements, were associated with carotid artery IMT or focal carotid artery plaque. This study provides limited support for the hypothesis that increased dietary intake of vitamin E and increased plasma lycopene may decrease the risk of atherosclerosis. No benefit was demonstrated for supplemental antioxidant vitamin use.

Homeostasis Model Assessment of Insulin Resistance in Relation to the Incidence of Cardiovascular Disease The San Antonio Heart Study

Article

Aug 2002
DIABETES CARE

The prospective association between insulin levels and risk of cardiovascular disease (CVD) is controversial. The objective of the present study was to investigate the relationship of the homeostasis model assessment of insulin resistance (HOMA-IR), as well as insulin levels, with risk of nonfatal and fatal CVD over the 8-year follow-up of the San Antonio Heart Study. Between 1984 and 1988, randomly selected Mexican-American and non-Hispanic white residents of San Antonio participated in baseline examinations that included fasting blood samples for glucose, insulin, and lipids, a glucose tolerance test, anthropometric measurements, and a lifestyle questionnaire. Between 1991 and 1996, 2,569 subjects who were free of diabetes at baseline were reexamined using the same protocol. Over the follow-up period, 187 subjects experienced an incident cardiovascular event (heart attack, stroke, heart surgery, angina, or CVD death). Logistic regression analysis indicated that risk of a CVD event increased across quintiles of HOMA-IR after adjustment for age, sex, and ethnicity (P for trend <0.0001; quintile 5 vs. quintile 1, odds ratio [OR] 2.52, 95% CI 1.46-4.36). Additional adjustment for LDL, triglyceride, HDL, systolic blood pressure, smoking, alcohol consumption, exercise, and waist circumference only modestly reduced the magnitude of these associations (P for trend 0.02; quintile 5 vs. quintile 1, OR 1.94, 95% CI 1.05-3.59). Furthermore, there were no significant interactions between HOMA-IR and ethnicity, sex, hypertension, dyslipidemia, glucose tolerance (impaired glucose tolerance versus normal glucose tolerance), or obesity. The magnitude and direction of the relationship between insulin concentration and incident CVD were similar. We found a significant association between HOMA-IR and risk of CVD after adjustment for multiple covariates. The topic remains controversial, however, and additional studies are required, particularly among women and minority populations.

Lewington S, Clarke R, Qizilbash N, Peto R, Collins R and Prospective Studies Collaboration. Age-specific relevance of usual blood pressure to vascular mortality: A meta-analysis of individual data for one million adults in 61 prospective studies. The Lancet 2002; 360: 1903-1913

Article

Jan 2003

The age-specific relevance of blood pressure to cause-specific mortality is best assessed by collaborative meta-analysis of individual participant data from the separate prospective studies. Information was obtained on each of one million adults with no previous vascular disease recorded at baseline in 61 prospective observational studies of blood pressure and mortality. During 12.7 million person-years at risk, there were about 56000 vascular deaths (12000 stroke, 34000 ischaemic heart disease [IHD], 10000 other vascular) and 66000 other deaths at ages 40-89 years. Meta-analyses, involving "time-dependent" correction for regression dilution, related mortality during each decade of age at death to the estimated usual blood pressure at the start of that decade. Within each decade of age at death, the proportional difference in the risk of vascular death associated with a given absolute difference in usual blood pressure is about the same down to at least 115 mm Hg usual systolic blood pressure (SBP) and 75 mm Hg usual diastolic blood pressure (DBP), below which there is little evidence. At ages 40-69 years, each difference of 20 mm Hg usual SBP (or, approximately equivalently, 10 mm Hg usual DBP) is associated with more than a twofold difference in the stroke death rate, and with twofold differences in the death rates from IHD and from other vascular causes. All of these proportional differences in vascular mortality are about half as extreme at ages 80-89 years as at ages 40-49 years, but the annual absolute differences in risk are greater in old age. The age-specific associations are similar for men and women, and for cerebral haemorrhage and cerebral ischaemia. For predicting vascular mortality from a single blood pressure measurement, the average of SBP and DBP is slightly more informative than either alone, and pulse pressure is much less informative. Throughout middle and old age, usual blood pressure is strongly and directly related to vascular (and overall) mortality, without any evidence of a threshold down to at least 115/75 mm Hg.

Intensive diabetes therapy and carotid intima-media thickness in Type 1 diabetes

Article

Jul 2003
NEW ENGL J MED

Cardiovascular disease causes severe morbidity and mortality in type 1 diabetes, although the specific risk factors and whether chronic hyperglycemia has a role are unknown. We examined the progression of carotid intima-media thickness, a measure of atherosclerosis, in a population with type 1 diabetes. As part of the Epidemiology of Diabetes Interventions and Complications (EDIC) study, the long-term follow-up of the Diabetes Control and Complications Trial (DCCT), 1229 patients with type 1 diabetes underwent B-mode ultrasonography of the internal and common carotid arteries in 1994-1996 and again in 1998-2000. We assessed the intima-media thickness in 611 subjects who had been randomly assigned to receive conventional diabetes treatment during the DCCT and in 618 who had been assigned to receive intensive diabetes treatment. At year 1 of the EDIC study, the carotid intima-media thickness was similar to that in an age- and sex-matched nondiabetic population. After six years, the intima-media thickness was significantly greater in the diabetic patients than in the controls. The mean progression of the intima-media thickness was significantly less in the group that had received intensive therapy during the DCCT than in the group that had received conventional therapy (progression of the intima-media thickness of the common carotid artery, 0.032 vs. 0.046 mm; P=0.01; and progression of the combined intima-media thickness of the common and internal carotid arteries, -0.155 vs. 0.007; P=0.02) after adjustment for other risk factors. Progression of carotid intima-media thickness was associated with age, and the EDIC base-line systolic blood pressure, smoking, the ratio of low-density lipoprotein to high-density lipoprotein cholesterol, and urinary albumin excretion rate and with the mean glycosylated hemoglobin value during the mean duration (6.5 years) of the DCCT. Intensive therapy during the DCCT resulted in decreased progression of intima-media thickness six years after the end of the trial.

Observations on localization of arterial plaque

Article

Aug 1962

Diabetes and diabetes-associated lipid abnormalities have distinct effects on initiation and progression of atherosclerotic lesions

Article

Oct 2004

Diabetes in humans accelerates cardiovascular disease caused by atherosclerosis. The relative contributions of hyperglycemia and dyslipidemia to atherosclerosis in patients with diabetes are not clear, largely because there is a lack of suitable animal models. We therefore have developed a transgenic mouse model that closely mimics atherosclerosis in humans with type 1 diabetes by breeding low-density lipoprotein receptor-deficient mice with transgenic mice in which type 1 diabetes can be induced at will. These mice express a viral protein under control of the insulin promoter and, when infected by the virus, develop an autoimmune attack on the insulin-producing beta cells and subsequently develop type 1 diabetes. When these mice are fed a cholesterol-free diet, diabetes, in the absence of associated lipid abnormalities, causes both accelerated lesion initiation and increased arterial macrophage accumulation. When diabetic mice are fed cholesterol-rich diets, on the other hand, they develop severe hypertriglyceridemia and advanced lesions, characterized by extensive intralesional hemorrhage. This progression to advanced lesions is largely dependent on diabetes-induced dyslipidemia, because hyperlipidemic diabetic and nondiabetic mice with similar plasma cholesterol levels show a similar extent of atherosclerosis. Thus, diabetes and diabetes-associated lipid abnormalities have distinct effects on initiation and progression of atherosclerotic lesions.

Molecular Mechanisms Linking Diabetes to the Accelerated Development of Atherosclerosis

Abstract

No full-text available

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