The arterial pathology in DM does not only include increased occurrence of atherosclerotic plaques but also comprises generalized arterial alterations, that is, endothelial dysfunction, increased stiffness, extracellular matrix (ECM) changes and calcifications, which can be observed in both atherosclerotic and nonatherosclerotic parts of the arterial tree. Generalized changes in the vascular ECM have been described among patients with T1DM, that is, for glycosaminoglycans, 3 glycoproteins, 4,5 and collagens. 6 More recently, alterations in the levels of the metalloproteinase, matrix metalloproteinase Background-The increased risk of cardiovascular diseases in type 2 diabetes mellitus has been extensively documented, but the origins of the association remain largely unknown. We sought to determine changes in protein expressions in arterial tissue from patients with type 2 diabetes mellitus and moreover hypothesized that metformin intake influences the protein composition. Methods and Results-We analyzed nonatherosclerotic repair arteries gathered at coronary bypass operations from 30 patients with type 2 diabetes mellitus and from 30 age-and sex-matched nondiabetic individuals. Quantitative proteome analysis was performed by isobaric tag for relative and absolute quantitation-labeling and liquid chromatography-mass spectrometry, tandem mass spectrometry analysis on individual arterial samples. The amounts of the basement membrane components, α1-type IV collagen and α2-type IV collagen, γ1-laminin and β2-laminin, were significantly increased in patients with diabetes mellitus. Moreover, the expressions of basement membrane components and other vascular proteins were significantly lower among metformin users when compared with nonusers. Patients treated with or without metformin had similar levels of hemoglobin A1c, cholesterol, and blood pressure. In addition, quantitative histomorphometry showed increased area fractions of collagen-stainable material in tunica intima and media among patients with diabetes mellitus. Conclusions-The distinct accumulation of arterial basement membrane proteins in type 2 diabetes mellitus discloses a similarity between the diabetic macroangiopathy and microangiopathy and suggests a molecular explanation behind the alterations in vascular remodeling, biomechanical properties, and aneurysm formation described in diabetes mellitus. The lower amounts of basement membrane components in metformin-treated individuals are compatible with the hypothesis of direct beneficial drug effects on the matrix composition in the vasculature. (Circ Cardiovasc Genet. 2015;8:727-735.

Endothelial cell (EC) insulin resistance and dysfunction, caused by diabetes, accelerates atherosclerosis. It is unknown whether specifically enhancing EC-targeted insulin action can decrease atherosclerosis in diabetes. Accordingly, overexpressing insulin receptor substrate-1 (IRS1) in the endothelia of Apoe−/− mice (Irs1/Apoe−/−) increased insulin signaling and function in the aorta. Atherosclerosis was significantly reduced in Irs1/ApoE−/− mice on diet-induced hyperinsulinemia and hyperglycemia. The mechanism of insulin’s enhanced antiatherogenic actions in EC was related to remarkable induction of NO action, which increases endothelin receptor B (EDNRB) expression and intracellular [Ca2+]. Using the mice with knockin mutation of eNOS, which had Ser1176 mutated to alanine (AKI), deleting the only known mechanism for insulin to activate eNOS/NO pathway, we observed that IRS1 overexpression in the endothelia of Aki/ApoE−/− mice significantly decreased atherosclerosis. Interestingly, endothelial EDNRB expression was selectively reduced in intima of arteries from diabetic patients and rodents. However, endothelial EDNRB expression was upregulated by insulin via P13K/Akt pathway. Finally EDNRB deletion in EC of Ldlr−/− and Irs1/Ldlr−/− mice decreased NO production and accelerated atherosclerosis, compared with Ldlr−/− mice. Accelerated atherosclerosis in diabetes may be reduced by improving insulin signaling selectively via IRS1/Akt in the EC by inducing EDNRB expression and NO production.

Cardiovascular disease is the leading cause of death in patients with type 2 diabetes mellitus (T2DM). We suggested that plasma osteoprotegerin (OPG), a strong, independent predictor of cardiovascular disease, could discriminate between anti-diabetic treatments depending on their benefits regarding cardiovascular disease. The South Danish Diabetes Study, an investigator-driven, randomized, controlled clinical trial lasting 2 years, was used to test this hypothesis in patient groups with different medication strategies (insulin aspart or NPH insulin, added either metformin ⁄ placebo or rosiglitazone ⁄ placebo). A total of 371 individuals were eligible for the study. Basic variables were analysed along with measurement of plasma OPG and HbA 1c at the beginning and end of the study. Only rosiglitazone treatment caused a significant decrease in plasma OPG concentrations (p = 0.003), while no significant change was seen in the other treatment groups. The effect of rosiglitazone on plasma OPG remained significant in a univariate analysis adjusted for change in HbA 1c (p = 0.013). Of note, the change in plasma OPG significantly correlated with HbA 1c improvement in rosiglitazone-treated patients (R = 0.29, p = 0.0002), while this correlation was poor in those not receiving rosiglitazone (R = 0.06, p = 0.48). Treatment with rosiglitazone among patients with T2DM reduces the concentration of plasma OPG. This is not seen with metformin despite similar reductions in HbA 1c . Alteration in the OPG ⁄ RANKL pathway by glitazones may have implications for the understanding of both cardiovascular effects and bone side effects of the drug.Cardiovascular disease (CVD) is the leading cause of death in patients with type 2 diabetes mellitus (T2DM) [1,2]. Thus, a high number of diabetic patients suffer from heart disease, cerebrovascular disease or peripheral arterial disease [3][4][5]. Measures of glycaemic status correlate with and predict large vessel disease, and a meta-analysis has indicated that there may be beneficial effects of intensive glucose-lowering treatment on CVD events in diabetes, although this is debated [4,[6][7][8]. Reports have shown that peroxisome proliferatoractivated receptor (PPAR) c agonists (e.g. glitazones) in addition to their effects on insulin sensitivity improve some cardiovascular risk factors, e.g. blood pressure, coagulation factors and inflammation [9][10][11]. Moreover, experimental studies seem to indicate that activity of PPAR-c agonists is beneficial in relation to the atherogenic process. However, a recent meta-analysis has indicated that glitazones might be associated with an increased risk of myocardial infarction [12]. Recently, the final evaluation of the RECORD study revealed an increased risk of heart failure with the drug, but no increase in death from cardiac causes or all-cause mortality. Moreover, an increased risk of some fractures, mainly in women, was found when rosiglitazone was added to other glucose-lowering therapy in patients with T2DM compatible with other studi...

In patients with atherosclerotic complications of diabetes, impaired neovascularization of ischemic tissue in the myocardium and lower limb limits the ability of these tissues to compensate for poor perfusion. We identified 10 novel insulin-regulated genes, among them Adm, Cited2, and Ctgf, which were downregulated in endothelial cells by insulin through FoxO1. CBP/p300-interacting transactivator with ED-rich tail 2 (CITED2), which was downregulated by insulin by up to 54%, is an important negative regulator of hypoxia-inducible factor (HIF) and impaired HIF signaling is a key mechanism underlying the impairment of angiogenesis in diabetes. Consistent with impairment of vascular insulin action, CITED2 was increased in cardiac endothelial cells from mice with diet-induced obesity and from db/db mice and was 3.8-fold higher in arterial tissue from patients with type 2 diabetes than control subjects without diabetes. CITED2 knockdown promoted endothelial tube formation and endothelial cell proliferation, whereas CITED2 overexpression impaired HIF activity in vitro. After femoral artery ligation, induction of an endothelial-specific HIF target gene in hind limb muscle was markedly upregulated in mice with endothelial cell deletion of CITED2, suggesting that CITED2 can limit HIF activity in vivo. We conclude that vascular insulin resistance in type 2 diabetes contributes to the upregulation of CITED2, which impairs HIF signaling and endothelial proangiogenic function.

BackgroundType 2 diabetes mellitus (T2DM) is an independent risk factor of cardiovascular disease (CVD), however, the underlying mechanisms are largely unknown. Using non-atherosclerotic internal thoracic arteries (ITAs) obtained from coronary artery bypass grafting, we previously identified a distinct elevation in the level of proteins comprising the arterial basement membrane in T2DM patients not treated with metformin. Altered transcription of genes encoding these proteins has not been observed, indicating alternative mechanisms of dysregulation.MethodsIn this study we screened for differential expression of arterial microRNAs (miRNAs) in T2DM patients to test the hypothesis that the arterial protein signature of diabetic patients is associated with dysregulation at the miRNA level, and further to lay the foundation for novel hypotheses addressing the increased CVD risk of T2DM patients. MiRNA isolated from fresh frozen ITAs [from 18 T2DM- (10 of which were subject to metformin treatment) and 30 non-diabetes mellitus (non-DM) patients] were analyzed by microarray, and miRNAs isolated from formalin-fixated paraffin-embedded (FFPE) ITAs were analyzed by quantitative PCR (qPCR) in an independent study group [26 T2DM- (15 of which were subject to metformin treatment) and 26 non-DM patients] to determine expression levels of miRNAs in a pre-defined panel of 12 miRNAs.ResultsUnexpectedly, no miRNAs were found to be affected by T2DM status in either of the two study groups.ConclusionsOur data suggest that alternatives to microRNA dysregulation underlie T2DM-associated protein changes in non-atherosclerotic arteries.Electronic supplementary materialThe online version of this article (10.1186/s12933-018-0715-y) contains supplementary material, which is available to authorized users.