The endothelium and vascular inflammation in diabetes

Premeal insulin decreases arterial stiffness in children with type 1 diabetes

OBJECTIVE

To determine the effects of omitting meal time insulin on arterial stiffness in children with type 1 diabetes.

RESEARCH DESIGN AND METHODS

In this prospective, randomized, crossover study, radial artery tonometry and augmentation index adjusted to heart rate 75 (AI₇₅ ) were used to measure arterial stiffness. Children were randomized to receive or omit premeal insulin and completed the crossover portion of the study on a subsequent day. AI₇₅ was determined when fasting, 1, and 2 h postmeal.

RESULTS

When comparing change in AI₇₅ from baseline to 1 h and baseline to 2 h, when subjects received premeal insulin vs. no insulin, AI₇₅ was 4.5 units lower at 1 h (p = 0.011, 95% CI:1.1 lower to 8 lower) and 4.3 units lower at 2 h (p = 0.062, 95% CI: 0.2 higher to 8.9 lower) (n = 40).

CONCLUSIONS

Arterial stiffness is decreased by premeal insulin in children with type 1 diabetes.

TWEAK blockade decreases atherosclerotic lesion size and progression through suppression of STAT1 signaling in diabetic mice

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK/Tnfsf12) is a cytokine implicated in different steps associated with vascular remodeling. However, the role of TWEAK under hyperglycemic conditions is currently unknown. Using two different approaches, genetic deletion of Tnfsf12 and treatment with a TWEAK blocking mAb, we have analyzed the effect of TWEAK inhibition on atherosclerotic plaque progression and stability in streptozotocin-induced diabetic ApoE deficient mice. Genetic inactivation of Tnfsf12 reduced atherosclerosis extension and severity in diabetic ApoE deficient mice. Tnfsf12 deficient mice display a more stable plaque phenotype characterized by lower lipid and macrophage content within atherosclerotic plaques. A similar phenotype was observed in diabetic mice treated with anti-TWEAK mAb. The proatherosclerotic effects of TWEAK were mediated, at least in part, by STAT1 activation and expression of proinflammatory target genes (CCL5, CXCL10 and ICAM-1), both in plaques of ApoE mice and in cultured vascular smooth muscle cells (VSMCs) under hyperglycemic conditions. Loss-of-function experiments demonstrated that TWEAK induces proinflammatory genes mRNA expression through its receptor Fn14 and STAT1 activation in cultured VSMCs. Overall, TWEAK blockade delay plaque progression and alter plaque composition in diabetic atherosclerotic mice. Therapies aimed to inhibit TWEAK expression and/or function could protect from diabetic vascular complications.

Second-generation versus first-generation drug-eluting stents in patients with and without diabetes mellitus: pooled analysis from the RESET and NEXT trials

The impact of second-generation drug-eluting stent (G2-DES) implantations compared with first-generation drug-eluting stents (G1-DES) implantations on long-term clinical outcomes after percutaneous coronary intervention in patients with and without diabetes mellitus (DM) has not yet been adequately assessed. This pooled analysis compared 3-year clinical outcomes between G1- and G2-DES according to the presence or absence of DM, using individual patient-level data from the RESET and NEXT trials. Among 6431 patients, G1-DES and G2-DES were used in 713 and 2211 patients, respectively, in the DM stratum, and 887 and 2620 patients, respectively, in the non-DM stratum. Cumulative incidence of and adjusted hazard ratio (HR) for target-lesion revascularization (TLR) were not significantly different between G2- and G1-DES in both strata [DM, 8.7 versus 10.1%, adjusted HR: 0.80, 95% confidence interval (CI) 0.59-1.10, P = 0.17; non-DM, 5.7 versus 6.2%, adjusted HR: 0.86, 95% CI 0.62-1.22, P = 0.38]. In the insulin-treated DM (ITDM), G2-DES had a significantly lower adjusted HR for TLR compared with G1-DES, although there was no significant difference in the non-ITDM (ITDM, adjusted HR: 0.54, 95% CI 0.32-0.96, P = 0.04; non-ITDM, adjusted HR: 0.95, 95% CI 0.66-1.42, P = 0.81). G2-DES provided similar risk for TLR in non-ITDM and non-DM patients compared with G1-DES. However, G2-DES compared with G1-DES had a lower risk for TLR among ITDM patients.

Far-infrared protects vascular endothelial cells from advanced glycation end products-induced injury via PLZF-mediated autophagy in diabetic mice

The accumulation of advanced glycation end products (AGEs) in diabetic patients induces vascular endothelial injury. Promyelocytic leukemia zinc finger protein (PLZF) is a transcription factor that can be activated by low-temperature far-infrared (FIR) irradiation to exert beneficial effects on the vascular endothelium. In the present study, we investigated the influence of FIR-induced PLZF activation on AGE-induced endothelial injury both in vitro and in vivo. FIR irradiation inhibited AGE-induced apoptosis in human umbilical vein endothelial cells (HUVECs). PLZF activation increased the expression of phosphatidylinositol-3 kinases (PI3K), which are important kinases in the autophagic signaling pathway. FIR-induced PLZF activation led to autophagy in HUVEC, which was mediated through the upregulation of PI3K. Immunofluorescence staining showed that AGEs were engulfed by HUVECs and localized to lysosomes. FIR-induced autophagy promoted AGEs degradation in HUVECs. In nicotinamide/streptozotocin-induced diabetic mice, FIR therapy reduced serum AGEs and AGEs deposition at the vascular endothelium. FIR therapy also reduced diabetes-induced inflammatory markers in the vascular endothelium and improved vascular endothelial function. These protective effects of FIR therapy were not found in PLZF-knockout mice. Our data suggest that FIR-induced PLZF activation in vascular endothelial cells protects the vascular endothelium in diabetic mice from AGE-induced injury.

Matrix stiffness exerts biphasic control over monocyte-endothelial adhesion via Rho-mediated ICAM-1 clustering

Leukocyte-endothelial adhesion is a critical early step in chronic vascular inflammation associated with diabetes, emphysema, and aging. Importantly, these conditions are also marked by abnormal subendothelial matrix crosslinking (stiffness). Yet, whether and how abnormal matrix stiffness contributes to leukocyte-endothelial adhesion remains poorly understood. Using a co-culture of human monocytic cells and human microvascular endothelial cells (ECs) grown on matrices of tunable stiffness, we demonstrate that matrix stiffness exerts biphasic control over monocyte-EC adhesion, with both matrix softening and stiffening eliciting a two-fold increase in this adhesive interaction. This preferential endothelial adhesivity on softer and stiffer matrices was consistent with a significant increase in α-actinin-4-associated endothelial ICAM-1 clustering, a key determinant of monocyte-EC adhesion. Further, the enhanced ICAM-1 clustering on soft and stiff matrices correlated strongly with an increase in Rho activity and ROCK2 expression. Importantly, inhibition of Rho/ROCK activity blocked the effects of abnormal matrix stiffness on ICAM-1 clustering and monocyte-EC adhesion. Thus, these findings implicate matrix stiffness-dependent ICAM-1 clustering as an important regulator of vascular inflammation and provide the rationale for closely examining mechanotransduction pathways as new molecular targets for anti-inflammatory therapy.

Insulin Resistance and Endothelial Dysfunction Constitute a Common Therapeutic Target in Cardiometabolic Disorders

Insulin resistance and other risk factors for atherosclerosis, such as hypertension and hypercholesterolemia, promote endothelial dysfunction and lead to development of metabolic syndrome which constitutes an introduction to cardiovascular disease. The insulin resistance and endothelial dysfunction cross talk between each other by numerous metabolic pathways. Hence, targeting one of these pathologies with pleiotropic treatment exerts beneficial effect on another one. Combined and expletive treatment of hypertension, lipid disorders, and insulin resistance with nonpharmacological interventions and conventional pharmacotherapy may inhibit the transformation of metabolic disturbances to fully developed cardiovascular disease. This paper summarises the common therapeutic targets for insulin resistance, endothelial dysfunction, and vascular inflammatory reaction at molecular level and analyses the potential pleiotropic effects of drugs used currently in management of cardiovascular disease, metabolic syndrome, and diabetes.

Impaired coronary microcirculation in type 2 diabetic patients is associated with elevated circulating regulatory T cells and reduced number of IL-21R⁺ T cells

Background

Low-grade systemic inflammation is considered to participate in the progression of type 2 diabetes (T2D) and in diabetic complications.

Methods

To determine if circulating leukocytes were abnormally regulated in T2D patients, 8-color flow-cytometry (FACS) analysis was performed in a cross-sectional study of 37 T2D patients and 16 controls. Data obtained from the FACS analysis were compared to coronary flow reserve (CFR), assessed by Rb⁸²-PET-imaging, to uncover inflammatory signatures associated with impaired CFR.

Results

Presence of T2D was associated with T cell attenuation characterized by reduced overall T cell, Th17, IL-21R⁺, Treg’s and TLR4⁺ T cells, while the monocyte population showed enhanced TLR4 expression. Further, our data revealed reduced M1-like CD11c expression in T2D which was associated with impaired CFR. In contrast, we show, for the first time in T2D, increased TLR4 expression on CD8 T cells, increased Treg cell number and Treg maturation and reduced IL-21R expression on CD8 T cells to be functionally associated with impaired CFR.

Conclusions

Our demonstration that HbA1c inversely correlates to several T cell populations suggests that T cells may play disease modulating roles in T2D. Further, the novel association between impaired CFR and regulatory T cells and IL-21R⁺ T cells imply an intricate balance in maintaining tissue homeostasis in vascular diabetic complications.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-016-0378-5) contains supplementary material, which is available to authorized users.

UPLC-MS/MS-Based Profiling of Eicosanoids in RAW264.7 Cells Treated with Lipopolysaccharide

While both the pro- and anti-inflammatory effects of several eicosanoids have been widely studied, the degree of inflammation in cells that results from various eicosanoids has yet to be comprehensively studied. The objective of this study was to assess the effect of lipopolysaccharide (LPS) treatment on eicosanoid content in RAW264.7 cells. An Ultra performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS)-based profiling method was used to analyze the eicosanoid contents of RAW264.7 cells treated with different LPS concentrations. The profiling data were subjected to statistical analyses, such as principal component analysis (PCA) and hierarchical clustering analysis. LPS treatment increased nitric oxide production and secretion of pro-inflammatory cytokines, such as tumor necrosis factor-α and interleukin-6, in a concentration-dependent manner. In total, 79 eicosanoids were identified in the cells. RAW264.7 cells treated with different LPS concentrations were well differentiated in the PCA score plot. A heatmap was used to identify the eicosanoids that were up- or down-regulated according to the degree of inflammation and LPS concentration. Thirty-nine eicosanoids were upregulated and seven were down-regulated by LPS treatment in a concentration-dependent manner. Our novel UPLC-MS/MS technique can profile eicosanoids, and can evaluate the correlations between inflammation and eicosanoid metabolism.

Admission plasma glucose levels within the normal to mildly impaired range and the outcome of patients with acute coronary syndrome

BACKGROUND

Elevated admission plasma glucose levels >140 mg/dl are associated with adverse clinical outcomes in both diabetic and non-diabetic patients admitted with acute coronary syndrome (ACS). We aimed to evaluate the association between admission plasma glucose levels <140 mg/dl and the outcome of non-diabetic patients admitted with acute coronary syndrome.

METHODS

The study population consisted of patients with acute coronary syndrome included in the Acute Coronary Syndrome Israeli Survey during 2000-2013. Diabetic patients were excluded. The primary endpoint was all-cause mortality at one year.

RESULTS

The 452 0 patients had a mean age of 61.7±13.5 years and were stratified into four quartiles according to admission plasma glucose (60-94, 95-105, 106-119, 120-140 mg/dl). Patients with higher admission plasma glucose were older and included a higher percentage of smokers. In addition, the higher the glucose so also did they have a poorer risk factor profile including a higher body mass index, total and low-density lipoprotein cholesterol and triglyceride levels, and lower high-density lipoprotein cholesterol levels. During the first year 5.2% of patients died. A comparison of one-year mortality according to admission plasma glucose quartiles demonstrated a significant and progressive increase in mortality risk as admission plasma glucose rose (3.5%, 4.1%, 6.1%, 6.4%, respectively, p=0.001). However, this association lost its clinical significance following a multivariate analysis ( p=0.08).

CONCLUSIONS

High admission plasma glucose levels within the normal to mildly impaired range are associated with increased one-year mortality in non-diabetic acute coronary syndrome patients. However, the higher glucose level is probably not the cause for the adverse outcome but rather a marker for high risk. Our findings support the definition of 140 mg/dl as the cutoff for clinically acceptable admission glucose levels in patients with acute coronary syndrome.

Assessment of oxidative stress and inflammation in prediabetes-A hospital based cross-sectional study

BACKGROUND AND AIM

Prediabetes is associated with dysglycemia, obesity, inflammation and endothelial dysfunction, contributing towards the pathogenesis of cardiovascular diseases rendering them vulnerable for the same. The current study intended to explore the risk of cardiovascular disease (CVD) related with prediabetes by assessing oxidative stress and inflammation using serum interleukin-6 (IL-6), myeloperoxidase (MPO) and urine microalbumin (MA) and their correlation with fasting plasma glucose (FPG) and physical measurements.

MATERIALS AND METHODS

Based on FPG values, 80 subjects were grouped into prediabetes and healthy controls. IL-6 and MPO were estimated in serum sample whereas MA was estimated in random urine sample.

RESULTS

Prediabetes group had significantly increased (p<0.05) mean anthropometric measurements and IL-6, MPO and MA as compared to healthy controls. MPO had significant correlation with FPG (r-0.388) in the prediabetes group. IL-6 and MPO showed a positive correlation with body mass index (BMI (r-0.339, r-0.327)), waist circumference (WC (r-484, r-0.493)) and waist-to-hip ratio (WHR (r-0.430, r-0.493)) while MA did not correlate with FPG and anthropometric measurements.

CONCLUSION

This study suggests that prediabetes is associated with central adiposity, inflammation and oxidative stress predisposing them to an increased risk for CVD.

Soluble Forms of Intercellular and Vascular Cell Adhesion Molecules Independently Predict Progression to Type 2 Diabetes in Mexican American Families

Objective

While the role of type 2 diabetes (T2D) in inducing endothelial dysfunction is fairly well-established the etiological role of endothelial dysfunction in the onset of T2D is still a matter of debate. In the light of conflicting evidence in this regard, we conducted a prospective study to determine the association of circulating levels of soluble intercellular adhesion molecule 1 (sICAM-1) and soluble vessel cell adhesion molecule 1 (sVCAM-1) with incident T2D.

Methods

Data from this study came from 1,269 Mexican Americans of whom 821 initially T2D-free individuals were longitudinally followed up in the San Antonio Family Heart Study. These individuals were followed for 9752.95 person-years for development of T2D. Prospective association of sICAM-1 and sVCAM-1 with incident T2D was studied using Kaplan-Meier survival plots and mixed effects Cox proportional hazards modeling to account for relatedness among study participants. Incremental value of adhesion molecule biomarkers was studied using integrated discrimination improvement (IDI) and net reclassification improvement (NRI) indexes.

Results

Decreasing median values for serum concentrations of sICAM-1 and sVCAM-1 were observed in the following groups in this order: individuals with T2D at baseline, individuals who developed T2D during follow-up, individuals with prediabetes at baseline and normal glucose tolerant (NGT) individuals who remained T2D-free during follow-up. Top quartiles for sICAM-1 and sVCAM-1 were strongly and significantly associated with homeostatic model of assessment—insulin resistance (HOMA-IR). Mixed effects Cox proportional hazards modeling revealed that after correcting for important clinical confounders, high sICAM-1 and sVCAM-1 concentrations were associated with 2.52 and 1.99 times faster progression to T2D as compared to low concentrations, respectively. Individuals with high concentrations for both sICAM-1 and sVCAM-1 progressed to T2D 3.42 times faster than those with low values for both sICAM-1 and sVCAM-1. The results were similar in women in reproductive age group and the remainder of the cohort. Inclusion of sICAM-1 and sVCAM-1 in predictive models significantly improved reclassification and discrimination. The majority of these results were seen even when the analyses were restricted to NGT individuals.

Conclusion

Serum concentrations of sICAM-1 and sVCAM-1 independently and additively predict future T2D and represent important candidate biomarkers of T2D.

Basement membrane stiffening promotes retinal endothelial activation associated with diabetes

Endothelial activation is a hallmark of the high-glucose (HG)-induced retinal inflammation associated with diabetic retinopathy (DR). However, precisely how HG induces retinal endothelial activation is not fully understood. We hypothesized that HG-induced up-regulation of lysyl oxidase (LOX), a collagen-cross-linking enzyme, in retinal capillary endothelial cells (ECs) enhances subendothelial basement membrane (BM) stiffness, which, in turn, promotes retinal EC activation. Diabetic C57BL/6 mice exhibiting a 70 and 50% increase in retinal intercellular adhesion molecule (ICAM)-1 expression and leukocyte accumulation, respectively, demonstrated a 2-fold increase in the levels of BM collagen IV and LOX, key determinants of capillary BM stiffness. Using atomic force microscopy, we confirmed that HG significantly enhances LOX-dependent subendothelial matrix stiffness in vitro, which correlated with an ∼2.5-fold increase in endothelial ICAM-1 expression, a 4-fold greater monocyte-EC adhesion, and an ∼2-fold alteration in endothelial NO (decrease) and NF-κB activation (increase). Inhibition of LOX-dependent subendothelial matrix stiffening alone suppressed HG-induced retinal EC activation. Finally, using synthetic matrices of tunable stiffness, we demonstrated that subendothelial matrix stiffening is necessary and sufficient to promote EC activation. These findings implicate BM stiffening as a critical determinant of HG-induced retinal EC activation and provide a rationale for examining BM stiffness and underlying mechanotransduction pathways as therapeutic targets for diabetic retinopathy.

Differences in the performance of PCL-based vascular grafts as abdominal aorta substitutes in healthy and diabetic rats

Diabetes exacerbates the regeneration process after in vivo implantation of vascular graft.

Insights into the molecular mechanisms of diabetes-induced endothelial dysfunction: focus on oxidative stress and endothelial progenitor cells

Diabetes mellitus is a heterogeneous, multifactorial, chronic disease characterized by hyperglycemia owing to insulin insufficiency and insulin resistance (IR). Recent epidemiological studies showed that the diabetes epidemic affects 382 million people worldwide in 2013, and this figure is expected to be 600 million people by 2035. Diabetes is associated with microvascular and macrovascular complications resulting in accelerated endothelial dysfunction (ED), atherosclerosis, and cardiovascular disease (CVD). Unfortunately, the complex pathophysiology of diabetic cardiovascular damage is not fully understood. Therefore, there is a clear need to better understand the molecular pathophysiology of ED in diabetes, and consequently, better treatment options and novel efficacious therapies could be identified. In the light of recent extensive research, we re-investigate the association between diabetes-associated metabolic disturbances (IR, subclinical inflammation, dyslipidemia, hyperglycemia, dysregulated production of adipokines, defective incretin and gut hormones production/action, and oxidative stress) and ED, focusing on oxidative stress and endothelial progenitor cells (EPCs). In addition, we re-emphasize that oxidative stress is the final common pathway that transduces signals from other conditions-either directly or indirectly-leading to ED and CVD.

Pathophysiological Role of Peroxynitrite Induced DNA Damage in Human Diseases: A Special Focus on Poly(ADP-ribose) Polymerase (PARP)

Peroxynitrite is formed in biological systems when nitric oxide and superoxide rapidly interact at near equimolar ratio. Peroxynitrite, though not a free radical by chemical nature, is a powerful oxidant which reacts with proteins, DNA and lipids. These reactions trigger a wide array of cellular responses ranging from subtle modulations of cell signaling to overwhelming oxidative injury, committing cells to necrosis or apoptosis. The present review outlines the various peroxynitrite-induced DNA modifications with special mention to the formation of 8-nitroguanine and 8-oxoguanine as well as the induction of DNA single strand breakage. Low concentrations of peroxynitrite cause apoptotic death, whereas higher concentrations cause necrosis with cellular energetics (ATP and NAD(+)) serving as control between the two modes of cell death. DNA damage induced by peroxynitrite triggers the activation of DNA repair systems. A DNA nick sensing enzyme, poly(ADP-ribose) polymerase-1 (PARP-1) becomes activated upon detecting DNA breakage and it cleaves NAD(+) into nicotinamide and ADP-ribose and polymerizes the latter on nuclear acceptor proteins. Over-activation of PARP induced by peroxynitrite consumes NAD(+) and consequently ATP decreases, culminating in cell dysfunction, apoptosis or necrosis. This mechanism has been implicated in the pathogenesis of various diseases like diabetes, cardiovascular diseases and neurodegenerative diseases. In this review, we have discussed the cytotoxic effects (apoptosis and necrosis) of peroxynitrite in the etiology of the mentioned diseases, focusing on the role of PARP in DNA repair in presence of peroxynitrite.

Diabetic cardiomyopathy: An expression of stage B heart failure with preserved ejection fraction

Heart failure is now recognized as a progressive disease in which patients transition through the stages of being at risk of heart failure (stage A), to asymptomatic structural heart disease (stage B), to clinical manifestations of heart failure (stage C) and finally end-stage or refractory heart failure (stage D). This review outlines the key role of diabetes mellitus as a stage A risk factor for heart failure with preserved ejection fraction, and asymptomatic diabetic cardiomyopathy, referring to the presence of left ventricular diastolic dysfunction in diabetic patients without coronary artery disease, hypertension or other potential aetiologies, as an expression of stage B heart failure with preserved ejection fraction at high risk of transitioning to symptomatic stage C heart failure with preserved ejection fraction. The data presented call for better recognition of the unique phenotype of diabetic cardiomyopathy with preserved ejection fraction and elevated diastolic stiffness as a manifestation of stage B heart failure with preserved ejection fraction that should be targeted for risk management and preventive strategies.

Statins as Pleiotropic Modifiers of Vascular Oxidative Stress and Inflammation

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the industrialized world and in the future is expected to be the number one killer worldwide. The main cause underlying CVD is atherosclerosis. A key event in atherosclerosis initiation and progression is oxidative stress through the production of reactive oxygen species as well as endothelial dysfunction. Several pro- inflammatory and anti-inflammatory cytokines and proteins are involved in this process, complemented by activation of adhesion molecules that promote leukocyte rolling, tethering and infiltration into the sub-endothelial space. Statins represent the agent of choice since numerous clinical trials have verified that their pharmacological action extends beyond lipid lowering. Statins demonstrate direct anti-oxidant effects by scavenging free radicals and stimulating anti-oxidant enzymes while acting as regulators for cytokine, protein and adhesion molecule expression, all of which are involved in the atherosclerotic process. Statin use is considered one of the most efficient currently used interventions in managing CVD with the likely hood of remaining so in the near future.

Differential role of an NF-κB transcriptional response element in endothelial versus intimal cell VCAM-1 expression

RATIONALE

Human and murine Vcam1 promoters contain 2 adjacent nuclear factor-κB (NF-κB)-binding elements. Both are essential for cytokine-induced transcription of transiently transfected promoter-reporter constructs. However, the relevance of these insights to regulation of the endogenous Vcam1 gene and to pathophysiological processes in vivo remained unknown.

OBJECTIVE

Determine the role of the 5' NF-κB-binding element in expression of the endogenous Vcam1 gene.

METHODS AND RESULTS

Homologous recombination in embryonic stem cells was used to inactivate the 5' NF-κB element in the Vcam1 promoter and alter 3 nucleotides in the 5' untranslated region to allow direct comparison of wild-type versus mutant allele RNA expression and chromatin configuration in heterozygous mice. Systemic treatment with inflammatory cytokines or endotoxin (lipopolysaccharide) induced lower expression of the mutant allele relative to wild-type by endothelial cells in the aorta, heart, and lungs. The mutant allele also showed lower endothelial expression in 2-week atherosclerotic lesions in Vcam1 heterozygous/low-density lipoprotein receptor-deficient mice fed a cholesterol-rich diet. In vivo chromatin immunoprecipitation assays of heart showed diminished lipopolysaccharide-induced association of RNA polymerase 2 and NF-κB p65 with the mutant promoter. In contrast, expression of mutant and wild-type alleles was comparable in intimal cells of wire-injured carotid artery and 4- to 12-week atherosclerotic lesions.

CONCLUSIONS

This study highlights differences between in vivo and in vitro promoter analyses, and reveals a differential role for a NF-κB transcriptional response element in endothelial vascular cell adhesion molecule-1 expression induced by inflammatory cytokines or a cholesterol-rich diet versus intimal cell expression in atherosclerotic lesions and injured arteries.

Switching α-glucosidase inhibitors to miglitol reduced glucose fluctuations and circulating cardiovascular disease risk factors in type 2 diabetic Japanese patients

Background and Objectives

In this study we examined the effects of switching α-glucosidase inhibitors (α-GI) from acarbose or voglibose to miglitol on glucose fluctuations and circulating concentrations of cardiovascular disease risk factors, such as soluble adhesion molecules (sE-selectin, sICAM-1 and sVCAM-1), a chemokine monocyte chemoattractant protein (MCP)-1, plasminogen activator inhibitor-1, and fatty acid-binding protein 4, in type 2 diabetic patients for 3 months.

Methods

We enrolled 47 Japanese patients with type 2 diabetes, with HbA_1c levels with 7.26 ± 0.5 % (mean ± standard deviation), and who were treated with the highest approved dose of acarbose (100 mg/meal) or voglibose (0.3 mg/meal) in combination with insulin or sulfonylurea. Patients’ prior α-GIs were switched to a medium dose of miglitol (50 mg/meal), and the new treatments were maintained for 3 months. Thirty-five patients who completed the 3-month study and provided serum samples were analyzed.

Results

The switch to miglitol for 3 months did not affect HbA_1c, fasting glucose, triglycerides, total-cholesterol or C-reactive protein levels, or result in any adverse events. Glucose fluctuations were significantly improved by the change in treatment (M-value: 10.54 ± 4.32 to 8.36 ± 2.54), while serum protein concentrations of MCP-1 (525.04 ± 288.06–428.11 ± 163.78 pg/mL) and sE-selectin (18.65 ± 9.77–14.50 ± 6.26 ng/mL) were suppressed.

Conclusion

Our results suggest that switching from acarbose or voglibose to miglitol for 3 months suppressed glucose fluctuations and serum protein levels of MCP-1 and sE-selectin in type 2 diabetic Japanese patients, with fewer adverse effects.

Chronic Inhibition of PDE5 Limits Pro-Inflammatory Monocyte-Macrophage Polarization in Streptozotocin-Induced Diabetic Mice

Diabetes mellitus is characterized by changes in endothelial cells that alter monocyte recruitment, increase classic (M1-type) tissue macrophage infiltration and lead to self-sustained inflammation. Our and other groups recently showed that chronic inhibition of phosphodiesterase-5 (PDE5i) affects circulating cytokine levels in patients with diabetes; whether PDE5i also affects circulating monocytes and tissue inflammatory cell infiltration remains to be established. Using murine streptozotocin (STZ)-induced diabetes and in human vitro cell-cell adhesion models we show that chronic hyperglycemia induces changes in myeloid and endothelial cells that alter monocyte recruitment and lead to self-sustained inflammation. Continuous PDE5i with sildenafil (SILD) expanded tissue anti-inflammatory TIE2-expressing monocytes (TEMs), which are known to limit inflammation and promote tissue repair. Specifically, SILD: 1) normalizes the frequency of circulating pro-inflammatory monocytes triggered by hyperglycemia (53.7 ± 7.9% of CD11b⁺Gr-1⁺ cells in STZ vs. 30.4 ± 8.3% in STZ+SILD and 27.1 ± 1.6% in CTRL, P<0.01); 2) prevents STZ-induced tissue inflammatory infiltration (4-fold increase in F4/80+ macrophages in diabetic vs. control mice) by increasing renal and heart anti-inflammatory TEMs (30.9 ± 3.6% in STZ+SILD vs. 6.9 ± 2.7% in STZ, P <0.01, and 11.6 ± 2.9% in CTRL mice); 3) reduces vascular inflammatory proteins (iNOS, COX2, VCAM-1) promoting tissue protection; 4) lowers monocyte adhesion to human endothelial cells in vitro through the TIE2 receptor. All these changes occurred independently from changes of glycemic status. In summary, we demonstrate that circulating renal and cardiac TEMs are defective in chronic hyperglycemia and that SILD normalizes their levels by facilitating the shift from classic (M1-like) to alternative (M2-like)/TEM macrophage polarization. Restoration of tissue TEMs with PDE5i could represent an additional pharmacological tool to prevent end-organ diabetic complications.

Chebulagic acid inhibits the LPS-induced expression of TNF-α and IL-1β in endothelial cells by suppressing MAPK activation

Inflammatory response in the vasculature, including the overexpression of tumor necrosis factor (TNF)-α and interleukin (IL)-1β, has been demonstrated to increase the risk of thrombosis development. Chebulagic acid (CA) is a key chemical component in the traditional Mongolian anti-thrombotic drug Garidi-13, and has been suggested to exert anti-inflammatory and anti-infective effects. The present study aimed to evaluate the regulatory impact of CA on a number of biological processes, including lipopolysaccharide (LPS)-induced inflammation, LPS-promoted mitogen-activated protein kinase (MAPK) activation and the expression of toll-like receptor (TLR)4 in EA.hy926 human endothelial cells. The results indicated that CA significantly inhibited the LPS-induced upregulation of TNF-α and IL-1β in a dose- and time-dependent manner. Furthermore, LPS-activated MAPK signaling was inhibited by CA treatment in the EA.hy926 cells. However, TLR4, which serves a key function in LPS-induced inflammation as the receptor of LPS, was not regulated by the CA treatment. In summary, the results of the present study indicate that CA inhibits the LPS-induced promotion of TNF-α and IL-1β in endothelial cells by suppressing MAPK activation, which may contribute to the anti-thrombotic effect of Garidi-13.

Long-term high fat feeding of rats results in increased numbers of circulating microvesicles with pro-inflammatory effects on endothelial cells

Obesity and type 2 diabetes lead to dramatically increased risks of atherosclerosis and CHD. Multiple mechanisms converge to promote atherosclerosis by increasing endothelial oxidative stress and up-regulating expression of pro-inflammatory molecules. Microvesicles (MV) are small ( < 1 μm) circulating particles that transport proteins and genetic material, through which they are able to mediate cell-cell communication and influence gene expression. Since MV are increased in plasma of obese, insulin-resistant and diabetic individuals, who often exhibit chronic vascular inflammation, and long-term feeding of a high-fat diet (HFD) to rats is a well-described model of obesity and insulin resistance, we hypothesised that this may be a useful model to study the impact of MV on endothelial inflammation. The number and cellular origin of MV from HFD-fed obese rats were characterised by flow cytometry. Total MV were significantly increased after feeding HFD compared to feeding chow (P< 0·001), with significantly elevated numbers of MV derived from leucocyte, endothelial and platelet compartments (P< 0·01 for each cell type). MV were isolated from plasma and their ability to induce reactive oxygen species (ROS) formation and vascular cell adhesion molecule (VCAM)-1 expression was measured in primary rat cardiac endothelial cells in vitro. MV from HFD-fed rats induced significant ROS (P< 0·001) and VCAM-1 expression (P= 0·0275), indicative of a pro-inflammatory MV phenotype in this model of obesity. These findings confirm that this is a useful model to further study the mechanisms by which diet can influence MV release and subsequent effects on cardio-metabolic health.

Characterization of sleep breathing pattern in patients with type 2 diabetes: sweet sleep study

BACKGROUND

Although sleep apnea-hypopnea syndrome (SAHS) is highly prevalent in patients with type 2 diabetes (T2D), it is unknown whether or not subjects with and without T2D share the same sleep breathing pattern.

METHODOLOGY/PRINCIPAL FINDINGS

A cross-sectional study in patients with SAHS according to the presence (n = 132) or not (n = 264) of T2D. Both groups were matched by age, gender, BMI, and waist and neck circumferences. A subgroup of 125 subjects was also matched by AHI. The exclusion criteria included chronic respiratory disease, alcohol abuse, use of sedatives, and heart failure. A higher apnea hypopnea index (AHI) was observed in T2D patients [32.2 (10.2-114.0) vs. 25.6 (10.2-123.4) events/hours; p = 0.002). When sleep events were evaluated separately, patients with T2D showed a significant increase in apnea events [8.4 (0.1-87.7) vs. 6.3 (0.0-105.6) e/h; p = 0.044), as well as a two-fold increase in the percentage of time spent with oxygen saturation <90% [15.7 (0.0-97.0) vs. 7.9 (0.0-95.6) %; <0.001)], higher rates of oxygen desaturation events, and also higher daily sleepiness [7.0 (0.0-21.0) vs. 5.0 (0.0-21.0); p = 0.006)] than subjects without T2D. Significant positive correlations between fasting plasma glucose and AHI, the apnea events, and CT90 were observed. Finally, multiple linear regression analyses showed that T2D was independently associated with AHI (R2 = 0.217), the apnea index (R2 = 0.194), CT90 (R2 = 0.222), and desaturation events.

CONCLUSIONS/SIGNIFICANCE

T2D patients present a different pattern of sleep breathing than subject without diabetes. The most important differences are the severity of hypoxemia and the number of apneas whereas the incidence of hypopnea episodes is similar.

Associations of Self-Reported Erectile Function with Non-Invasive Measurements of Endothelial Function: A Preliminary Study

Purpose

To evaluate the association of self-reported erectile function and endothelial function using the EndoPAT device.

Materials and Methods

We prospectively enrolled 76 men (age≥40 years) after obtaining a complete medical history and a self-reported questionnaire (International Index of Erectile Function-5 [IIEF-5], SEP Q2, Q3). Endothelial function was noninvasively measured with an EndoPAT 2000, recorded as the reactive hyperemia index (RHI), and analyzed according to the patients' baseline characteristics.

Results

The mean patient age and IIEF-5 score were 62.50±8.56 years and 11.20±6.36, respectively. In comparing the RHI according to erectile dysfunction (ED) risk factors, the RHI was significantly lower in older subjects (p=0.004). There was no difference in the RHI according to age, body mass index, waist circumference, obesity, smoking habit, or other comorbidities. When the subjects were divided into four groups according to the severity of ED, no statistical differences in the RHI value were found among the groups. There was no difference in IIEF-5 according to the RHI when categorized according to the normal cutoff value or quartile ranges. The second subdomain of IIEF-5 (erection firmness) was significantly correlated with the RHI value (R=0.309, p=0.007); however, this was not the case with the other IIEF-5 subdomains. Self-assessment showed a tendency toward a negative correlation with the RHI value (R=-0.202, p=0.080).

Conclusions

The role of endothelial function measurement by the EndoPAT in the evaluation and management of ED patients remains inconclusive. However, further studies are needed to validate the role of endothelial function measurement, by the EndoPAT or any other device.

Diabetes, Endothelial Dysfunction, and Vascular Repair: What Should a Diabetologist Keep His Eye on?

Cardiovascular complications are the most common complications of diabetes mellitus. A prominent attribute of diabetic cardiovascular complications is accelerated atherosclerosis, considered as a still incurable disease, at least at more advanced stages. The discovery of endothelial progenitor cells (EPCs), able to replace old and injured mature endothelial cells and capable of differentiating into healthy and functional endothelial cells, has offered the prospect of merging the traditional theories on the pathogenesis of atherosclerosis with evolving concepts of vascular biology. The literature supports the notion that EPC alterations are involved in the pathogenesis of vascular diseases in diabetics, but at present many questions remain unanswered. In this review the aspects linking endothelial progenitor cells to the altered vascular biology in diabetes mellitus are discussed.

Correlation between blood lipid levels and chronic pancreatitis: a retrospective case-control study of 48 cases

The incidence of chronic pancreatitis (CP) is increasing, and dyslipidemia severely affects the health of middle-aged and elderly people. We investigated the association between blood lipid levels and CP. The serum lipid metabolic indices of 48 patients with CP (CP group) were summarized retrospectively. The physical examination results of 40 randomly selected healthy individuals were used as the normal control (NC) group. Statistical analyses of the blood lipid data were performed between the 2 groups using the case-control study method. High-density lipoprotein-cholesterol (HDL-c) levels decreased and fasting blood glucose (GLU) levels increased in the CP group compared with those in the NC group (P<0.01). Pearson correlation analysis results showed that serum amylase (AMY) was positively correlated with low-density lipoprotein-cholesterol (LDL-c; r=0.414, P<0.05), and urine AMY (UAMY) was positively correlated with total cholesterol (TC; r=0.614, P<0.01) and LDL-c (r=0.678, P<0.01). A binary logistic regression analysis showed that GLU (odds ratio [OR], 5.052; P<0.01) and TC (OR, 1.074; P<0.01) may be risk factors for CP, whereas HDL-c may be a CP protective factor (OR, 0.833; P<0.01). The HDL-c levels decreased and GLU levels increased in the CP group compared with those in the NC group; AMY was positively correlated with LDL-c and UAMY was positively correlated with TC and LDL-c; GLU and TC may be risk factors for CP; and HDL-c may be a CP protective factor. This may be the first time that such results have been reported. These findings will contribute to primary prevention and control of CP progression.

The involvement of aldosterone on vascular insulin resistance: implications in obesity and type 2 diabetes

Aldosterone, a mineralocorticoid hormone produced at the adrenal glands, controls corporal hydroelectrolytic balance and, consequently, has a key role in blood pressure adjustments. Aldosterone also has direct effects in many organs, including the vasculature, leading to many cellular events that influence proliferation, migration, inflammation, redox balance and apoptosis. Aldosterone effects depend on its binding to mineralocorticoid receptors (MR). Aldosterone binding to MR triggers two pathways, the genomic pathway and the non-genomic pathway. In the vasculature e.g., activation of the non-genomic pathway by aldosterone induces rapid effects that involve activation of kinases, phosphatases, transcriptional factors and NAD(P)H oxidases. Aldosterone also plays a crucial role on systemic and vascular insulin resistance, i.e. the inability of a tissue to respond to insulin. Insulin has a critical role on cell function and vascular insulin resistance is considered an early contributor to vascular damage. Accordingly, aldosterone impairs insulin receptor (IR) signaling by altering the phosphatidylinositol 3-kinase (PI3K)/nitric oxide (NO) pathway and by inducing oxidative stress and crosstalk between the IR and the insulin-like growth factor-1 receptor (IGF-1R). This mini-review focuses on the relationship between aldosterone and vascular insulin resistance. Evidence indicating MR antagonists as therapeutic tools to minimize vascular injury associated with obesity and diabetes type 2 is also discussed.

Ca(2+) handling alterations and vascular dysfunction in diabetes

More than 65% of patients with diabetes mellitus die from cardiovascular disease or stroke. Hyperglycemia, due to either reduced insulin secretion or reduced insulin sensitivity, is the hallmark feature of diabetes mellitus. Vascular dysfunction is a distinctive phenotype found in both types of diabetes and could be responsible for the high incidence of stroke, heart attack, and organ damage in diabetic patients. In addition to well-documented endothelial dysfunction, Ca(2+) handling alterations in vascular smooth muscle cells (VSMCs) play a key role in the development and progression of vascular complications in diabetes. VSMCs provide not only structural integrity to the vessels but also control myogenic arterial tone and systemic blood pressure through global and local Ca(2+) signaling. The Ca(2+) signalosome of VSMCs is integrated by an extensive number of Ca(2+) handling proteins (i.e. channels, pumps, exchangers) and related signal transduction components, whose function is modulated by endothelial effectors. This review summarizes recent findings concerning alterations in endothelium and VSMC Ca(2+) signaling proteins that may contribute to the vascular dysfunction found in the diabetic condition.

Simulated microgravity induces an inflammatory response in the common carotid artery of rats

Post-spaceflight orthostatic intolerance is one of the most important adverse effects after exposure to space microgravity, and there are still no effective countermeasures. It has been considered that arterial remodeling may play an important role in the occurrence of post-spaceflight orthostatic intolerance, but the cellular mechanisms remain unknown. In this study, we investigated whether an inflammatory response exists in the common carotid artery of rats exposed to simulated microgravity. For this, Sprague-Dawley rats were subjected to 4 weeks of hindlimb unweighting to simulate microgravity. The expression levels of the adhesion molecules E-selectin and vascular cell adhesion molecule-1 (VCAM-1), and the cytokine monocyte chemoattractant protein-1 (MCP-1) in the common carotid artery of simulated microgravity rats were evaluated by immunohistochemical staining, quantitative RT-PCR, and Western blot analyses. The recruitment of monocytes in the common carotid artery of rats exposed to simulated microgravity was investigated by en face immunofluorescence staining and monocyte binding assays. Our results provided convincing evidence that there is an inflammatory response in the common carotid artery of rats exposed to simulated microgravity. Our work suggests that the inflammatory response may be a novel cellular mechanism that is responsible for the arterial remodeling that occurs during exposure to microgravity.

Relationship between obesity, adipocytokines and inflammatory markers in type 2 diabetes: relevance for cardiovascular risk prevention

This study aimed to analyse the impact of obesity in type 2 diabetes (T2D) on adipocytokines (adiponectin, leptin and resistin) and inflammatory markers (TNF-α, IL-6 and hsCRP) as cardiovascular risk factors. A cross-sectional study comparing the basal levels of adipocytokines and inflammatory markers was done in 18 obese (BMI ≥ 30 kg/m²) (group A), 21 overweight (25 kg/m² ≤ BMI < 30 kg/m²) (group B), 25 non-obese T2D patients (group C) and 15 non-obese controls (group D). The lowest levels of adiponectin and the highest levels of leptin, resistin, TNF-α, IL-6 and hsCRP were found in group A. Adiponectin levels were significantly lower, and resistin, TNF-α, and hsCRP levels were elevated in group C vs. D. However, leptin and IL-6 levels differed significantly between groups A and B, but not between groups C and D. Moreover, we found a significant negative correlation between adiponectin and TNF-α, but not with other markers, which was independent of the presence of obesity. In contrast, leptin and resistin correlated with the inflammatory markers, and this correlation was obesity-dependent. Our results suggest that obesity influences cardiovascular risk primarily through changes in leptin and resistin and less efficiently at the level of adiponectin.

Protection of long-term treatment with huang-lian-jie-du-tang on vascular endothelium in rats with type 2 diabetes mellitus

BACKGROUND

Huang-Lian-Jie-Du-Tang (HLJDT) is the classical traditional Chinese recipe for heat clearance and detoxification and is used in diabetic patients in the clinical practice of traditional Chinese medicine.

OBJECTIVE

The aim of this study was to evaluate the protective effects of long-term treatment with HLJDT on vascular endothelial function in rats with type 2 diabetes mellitus (T2DM).

METHODS

The male T2DM model rats were induced by intraperitoneal injection of low-dose streptozotocin plus a high-fat and high-calorie laboratory diet. The T2DM animals were randomly divided into the T2DM model group, the low-dose HLJDT group (0.42 g/kg/d), and the high-dose HLJDT group (1.25 g/kg/d).

RESULTS

Administration of HLJDT (0.42 or 1.25 g/kg/d) for 8 weeks decreased the levels of serum fasting blood glucose, malondialdehyde, and vascular tissue interleukin 6 but raised the level of serum superoxide dismutase compared with the T2DM model group in a dose-dependent manner. In addition, HLJDT treatment restored the impaired endothelial-dependent vascular relaxation in aortic preparations from the T2DM model group in a dose-dependent manner.

CONCLUSIONS

Early and long-term treatments with HLJDT could have anti-inflammatory, antioxidant properties and could protect vascular endothelium from the cardiovascular complications associated with T2DM.

The 14 bp Del/Ins HLA-G polymorphism is related with high blood pressure in acute coronary syndrome and type 2 diabetes mellitus

Immunologic and inflammatory processes are involved in the pathogenesis of acute coronary syndrome (ACS) and type 2 diabetes mellitus (DM2). Human leukocyte antigen-G (HLA-G) is a negative regulator of the immune response. This study evaluates the 14 bp Del/Ins HLA-G polymorphism in ACS and DM2. Three hundred and seventy individuals from Western Mexico were recruited and categorized into three groups: ACS (86), DM2 without coronary complications (70), and healthy subjects (214). Genotyping of the 14 bp Del/Ins HLA-G polymorphism was performed by PCR and Native-PAGE. The most common risk factors were hypertension and overweight in ACS and DM2, respectively. The genetic distribution of the 14 bp Del/Ins HLA-G polymorphism showed no significant differences between groups (P ≥ 0.23). Nonetheless, the Ins/Ins genotype was associated with high blood pressure (HBP) in the DM2 group (OR_c = 1.65, P = 0.02). The genetic recessive model showed similar findings (OR_c = 3.03, P = 0.04). No association was found in ACS, with a P of 0.05; nevertheless, the prevalence of Ins/Ins carriers was quite similar to that found in the DM2-HBP group. The 14 bp Del/Ins HLA-G polymorphism was not a susceptibility factor for ACS or DM2; however, the Ins/Ins genotype might have contributed to the development of HBP in the studied groups.

Uncoupling of eNOS contributes to redox-sensitive leukocyte recruitment and microvascular leakage elicited by methylglyoxal

Elevated levels of the glycolysis metabolite methylglyoxal (MG) have been implicated in impaired leukocyte-endothelial interactions and vascular complications in diabetes, putative mechanisms of which remain elusive. Uncoupling of endothelial nitric oxide synthase (eNOS) was shown to be involved in endothelial dysfunction in diabetes. Whether MG contributes to these effects has not been elucidated. By using intravital microscopy in vivo, we demonstrate that MG-triggered reduction in leukocyte rolling velocity and increases in rolling flux, adhesion, emigration and microvascular permeability were significantly abated by scavenging reactive oxygen species (ROS). In murine cremaster muscle, MG treatment reduced tetrahydrobiopterin (BH4)/total biopterin ratio, increased arginase expression and stimulated ROS and superoxide production. The latter was significantly blunted by ROS scavengers Tempol (300μM) or MnTBAP (300μM), by BH4 supplementation (100μM) or by NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME; 20μM). In these tissues and cultured murine and human primary endothelial cells, MG increased eNOS monomerization and decreased BH4/total biopterin ratio, effects that were significantly mitigated by supplementation of BH4 or its precursor sepiapterin but not by L-NAME or tetrahydroneopterin, indicative of MG-triggered eNOS uncoupling. MG treatment further decreased the expression of guanosine triphosphate cyclohydrolase I in murine primary endothelial cells. MG-induced leukocyte recruitment was significantly attenuated by supplementation of BH4 or sepiapterin or suppression of superoxide by L-NAME confirming the role of eNOS uncoupling in MG-elicited leukocyte recruitment. Together, our study uncovers eNOS uncoupling as a pivotal mechanism in MG-induced oxidative stress, microvascular hyperpermeability and leukocyte recruitment in vivo.

Xanthohumol modulates inflammation, oxidative stress, and angiogenesis in type 1 diabetic rat skin wound healing

Type 1 diabetes mellitus is responsible for metabolic dysfunction, accompanied by chronic inflammation, oxidative stress, and endothelium dysfunction, and is often associated with impaired wound healing. Phenol-rich food improves vascular function, contributing to diabetes prevention. This study has evaluated the effect of phenol-rich beverage consumption in diabetic rats on wound healing, through angiogenesis, inflammation, and oxidative stress modulation. A wound-healing assay was performed in streptozotocin-induced diabetic Wistar rats drinking water, 5% ethanol, and stout beer with and without 10 mg/L xanthohumol (1), for a five-week period. Wounded skin microvessel density was reduced to normal values upon consumption of 1 in diabetic rats, being accompanied by decreased serum VEGF-A and inflammatory markers (IL-1β, NO, N-acetylglucosaminidase). Systemic glutathione and kidney and liver H2O2, 3-nitrotyrosine, and protein carbonylation also decreased to healthy levels after treatment with 1, implying an improvement in oxidative stress status. These findings suggest that consumption of xanthohumol (1) by diabetic animals consistently decreases inflammation and oxidative stress, allowing neovascularization control and improving diabetic wound healing.