Abnormal markers of endothelial cell activation and oxidative stress in children, adolescents and young adults with type 1 diabetes with no clinical vascular disease

Endothelial dysfunction and cardiovascular diseases: The role of human induced pluripotent stem cells and tissue engineering

Cardiovascular disease (CVD) remains to be the leading cause of death globally today and therefore the need for the development of novel therapies has become increasingly important in the cardiovascular field. The mechanism(s) behind the pathophysiology of CVD have been laboriously investigated in both stem cell and bioengineering laboratories. Scientific breakthroughs have paved the way to better mimic cell types of interest in recent years, with the ability to generate any cell type from reprogrammed human pluripotent stem cells. Mimicking the native extracellular matrix using both organic and inorganic biomaterials has allowed full organs to be recapitulated in vitro. In this paper, we will review techniques from both stem cell biology and bioengineering which have been fruitfully combined and have fueled advances in the cardiovascular disease field. We will provide a brief introduction to CVD, reviewing some of the recent studies as related to the role of endothelial cells and endothelial cell dysfunction. Recent advances and the techniques widely used in both bioengineering and stem cell biology will be discussed, providing a broad overview of the collaboration between these two fields and their overall impact on tissue engineering in the cardiovascular devices and implications for treatment of cardiovascular disease.

Heterogeneity of outcomes within diabetic patients with atrial fibrillation on edoxaban: a sub-analysis from the ETNA-AF Europe registry

BACKGROUND

Recent data have suggested that insulin-requiring diabetes mostly contributes to the overall increase of thromboembolic risk in patients with atrial fibrillation (AF) on warfarin. We evaluated the prognostic role of a different diabetes status on clinical outcome in a large cohort of AF patients treated with edoxaban.

METHODS

We accessed individual patients' data from the prospective, multicenter, ETNA-AF Europe Registry. We compared the rates of ischemic stroke/transient ischemic attack (TIA)/systemic embolism, myocardial infarction (MI), major bleeding and all-cause death at 2 years according to diabetes status.

RESULTS

Out of an overall population of 13,133 patients, 2885 had diabetes (22.0%), 605 of whom (21.0%) were on insulin. The yearly incidence of ischemic stroke/TIA/systemic embolism was 0.86% in patients without diabetes, 0.87% in diabetic patients not receiving insulin (p = 0.92 vs no diabetes) and 1.81% in those on insulin (p = 0.002 vs no diabetes; p = 0.014 vs diabetes not on insulin). The annual rates of MI and major bleeding were 0.40%, 0.43%, 1.04% and 0.90%, 1.10% and 1.71%, respectively. All-cause yearly mortality was 3.36%, 5.02% and 8.91%. At multivariate analysis, diabetes on insulin was associated with a higher rate of ischemic stroke/TIA/systemic embolism [adjusted HR 2.20, 95% CI 1.37-3.54, p = 0.0011 vs no diabetes + diabetes not on insulin] and all-cause death [aHR 2.13 (95% CI 1.68-2.68, p < 0.0001 vs no diabetes]. Diabetic patients not on insulin had a higher mortality [aHR 1.32 (1.11-1.57), p = 0.0015], but similar incidence of stroke/TIA/systemic embolism, MI and major bleeding, vs those without diabetes.

CONCLUSIONS

In a real-world cohort of AF patients on edoxaban, diabetes requiring insulin therapy, rather than the presence of diabetes per se, appears to be an independent factor affecting the occurrence of thromboembolic events during follow-up. Regardless of the diabetes type, diabetic patients had a lower survival compared with those without diabetes.

Topical Reappraisal of Molecular Pharmacological Approaches to Endothelial Dysfunction in Diabetes Mellitus Angiopathy

Diabetes mellitus (DM) is a frequent medical problem, affecting more than 4% of the population in most countries. In the context of diabetes, the vascular endothelium can play a crucial pathophysiological role. If a healthy endothelium—which is a dynamic endocrine organ with autocrine and paracrine activity—regulates vascular tone and permeability and assures a proper balance between coagulation and fibrinolysis, and vasodilation and vasoconstriction, then, in contrast, a dysfunctional endothelium has received increasing attention as a potential contributor to the pathogenesis of vascular disease in diabetes. Hyperglycemia is indicated to be the major causative factor in the development of endothelial dysfunction. Furthermore, many shreds of evidence suggest that the progression of insulin resistance in type 2 diabetes is parallel to the advancement of endothelial dysfunction in atherosclerosis. To present the state-of-the-art data regarding endothelial dysfunction in diabetic micro- and macroangiopathy, we constructed this literature review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We interrogated five medical databases: Elsevier, PubMed, PMC, PEDro, and ISI Web of Science.

Oxidative stress in youth with type 1 diabetes: Not only a matter of gender, age, and glycemic control

AIMS

We assessed whether oxidative stress (OS) is increased in children/adolescents with type 1 diabetes (T1D) compared to healthy peers. Moreover, we searched for OS predictors in the T1D population.

METHODS

We compared the concentration of serum derivatives of reactive oxygen metabolites (d-ROMs) in 412 children/adolescents with T1D (3.6-23.5 years old) to that of 138 healthy children/adolescents (1.2-19.2 years old) by ANOVA adjusted for age, gender, and BMI z-score (z-BMI). Applying a general linear model, in a subgroup of 331 patients using continuous glucose monitoring, we searched for predictors of d-ROMs among 3-day, 2-week, and 4-week metrics of glucose control and variability, such as mean blood glucose, percent time in range (70-180 mg/dl,TIR_70-180), coefficient of variation, and others, as well as among conventional cardiovascular risk factors like current and average HbA1c, z-BMI, blood pressure percentiles, and lipid concentrations recorded retrospectively over the entire follow-up period.

RESULTS

D-ROMs levels were significantly higher in children/adolescents with T1D compared to controls [371.9 (64.2) versus 324.9 (46.3), p < 10^-16]. Sex (B = 49.1, ƞ² = 0.14, p = 1.3 * 10^-9), age < 12 years in boys (B = 79.4, ƞ² = 0.074, p = 10^-7),3-day TIR_70-180 (B = -0.87, ƞ² = 0.048, p = 6.5 * 10^-5), and z-BMI (B = 7.4, ƞ² = 0.016, p = 0.022) predicted d-ROMs with an overall R² of 0.278.

CONCLUSIONS

OS is increased in youth with T1D and only partially predicted by gender, age, glucose control, and anthropometry. Other potential determinants of OS in this population should be targeted in future studies.

Role of diabetes and insulin use in the risk of stroke and acute myocardial infarction in patients with atrial fibrillation: A Medicare analysis

BACKGROUND

Atrial fibrillation (AF) is associated with elevated risk for ischemic stroke and myocardial infarction (MI). The aim of the study is to assess the role of insulin use on the risk of stroke and MI in AF patients with diabetes.

METHODS

We identified Medicare beneficiaries with new AF in 2011 to 2013. Primary outcomes were ischemic stroke and MI. Multivariate Cox regression models were used to assess the association between AF and time to stroke and MI. We adjusted for anticoagulant as a time-dependent covariate.

RESULTS

Out of 798,592 AF patients, 53,212 (6.7%) were insulin-requiring diabetics (IRD), 250,214 (31.3%) were non-insulin requiring diabetics (NIRD) and 495,166 (62%) were non-diabetics (ND). IRD had a higher risk of stroke when compared to NIRD (adjusted HR: 1.15, 95% CI 1.10-1.21) and ND (aHR 1.24, 95% CI 1.18-1.31) (P < .01 for both). The risk of stroke was higher in NIRD compared to ND (aHR 1.08, 95% CI 1.05-1.12). For the outcome of MI, IRD had a higher risk compared to NIRD (aHR 1.24, 95% CI 1.18-1.31) and ND (aHR 1.46, 95% CI 1.38-1.54)]. NIRD had a higher risk compared to ND (aHR 1.17, 95% CI 1.13-1.22). Anticoagulation were most effective at preventing stroke in ND [0.72 (0.69-0.75)], and NIRD [0.88 (0.85-0.92)], but were not associated with significant reduction in stroke in IRD [0.96 (0.89-1.04)].

CONCLUSION

There is an incremental risk of ischemic stroke and MI from non-diabetics to non-insulin diabetics with the highest risk in insulin users. Protective effect of anticoagulation is attenuated with insulin use.

Assessment of biomarkers of inflammation and premature atherosclerosis in adolescents with type-1 diabetes mellitus

Background Type-1 diabetes mellitus (T1DM) causes endothelial dysfunction and early atherosclerosis, which can result in premature coronary artery disease. The aim of this study was to determine the impact of glycemic control, vascular oxidative stress and inflammation on vascular health in adolescents with T1DM. Methods This was a cross-sectional study in adolescents with age- and sex-matched T1DM who were ≥12 years and were at least 2 years post-diagnosis. Recruitment was balanced to include individuals with hemoglobin A1c (HbA1c) ≤8.5% (n=27) or with HbA1c ≥9.5% (n=25). Biomarkers of inflammation were measured in the blood including C-reactive protein (CRP), interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1), E-selectin, fibrinogen and tumor necrosis factor-α (TNF-α). Carotid intima media thickness (cIMT) and peripheral arterial tonometry (PAT) were assessed. Results Plasma E-selectin level was significantly different between the two groups with higher levels in the group with HbA1c ≥9.5% (65.0±27.7 ng/mL vs. 48.8±21.5 ng/mL, p=0.02). Though cIMT and PAT were not significantly different between the groups, Pearson correlation showed a significant direct relationship between rising HbA1c and mean right cIMT (p=0.02; r=0.37), PAT (p=0.03, r=0.31) and fibrinogen (p=0.03, r=0.03). Conclusions Elevated E-selectin level is an early marker of oxidative stress in T1DM patients with an elevated HbA1c level. Suboptimal glycemic control as evidenced by a rising HbA1c causes early atherosclerosis.

The Effect of Chronic Inflammation and Oxidative and Endoplasmic Reticulum Stress in the Course of Metabolic Syndrome and Its Therapy

Metabolic syndrome (MetS) is highly associated with a modern lifestyle. The prevalence of MetS has reached epidemic proportion and is still rising. The main cause of MetS and finally type 2 diabetes occurrence is excessive nutrient intake, lack of physical activity, and inflammatory cytokines secretion. These factors lead to redistribution of body fat and oxidative and endoplasmic reticulum (ER) stress occurrence, resulting in insulin resistance, increase adipocyte differentiation, and much elevated levels of proinflammatory cytokines. Cellular therapies, especially mesenchymal stem cell (MSC) transplantation, seem to be promising in the MetS and type 2 diabetes treatments, due to their immunomodulatory effect and multipotent capacity; adipose-derived stem cells (ASCs) play a crucial role in MSC-based cellular therapies. In this review, we focused on etiopathology of MetS, especially on the crosstalk between chronic inflammation, oxidative stress, and ER stress and their effect on MetS-related disease occurrence, as well as future perspectives of cellular therapies. We also provide an overview of therapeutic approaches that target endoplasmic reticulum and oxidative stress.

Levels of adhesion molecules in peripheral blood correlat with stages of diabetic retinopathy and may serve as bio markers for microvascular complications

BACKGROUND

Proliferative diabetic retinopathy is a devastating complication of diabetes mellitus, developing within 15 years in 50% of patients with type 1 diabetes mellitus (DM) and in 10% of patients with type 2 DM. The correlation between levels of inflammatory markers in the peripheral blood and retinopathy staging has not been studied yet, and the purpose of this prospective study was to find a possible association between inflammation and staging of diabetic retinopathy.

METHODS

A prospective (pilot) study that measured level of adhesion molecules in the peripheral blood of 10 healthy subjects and 30 patients with type 2 diabetes mellitus. Patients were grouped by the degree of retinopathy: 10 without retinopathy, 10 with non-proliferative retinopathy [NPDR] and 10 with proliferative retinopathy [PDR]. After signing the consent form, an ophthalmologic examination was performed, and 10 mL of blood was drawn. In order to assess adhesion molecules' level serum samples were collected, frozen, and stored at a temperature of -80 °C until analysis was performed as one batch.

RESULTS

10 healthy volunteers and 30 patients were enrolled. Healthy volunteers were younger (36.6 ± 7.9 years) compared to patients (no retinopathy 64.5 ± 10.8 years, NPDR 71.4 ± 8.9 years, and PDR 63.3 ± 11.6 years) (p = .0003 for all groups of patients in comparison with the healthy subjects). VCAM-1 levels were increased by retinopathy staging - starting from 81.86 ± 3.80 ng/ml (healthy), 105.55 ± 1.37 ng/ml (no retinopathy), 111.78 ± 4.14 ng/ml (NPDR), and 123.45 ± 3.99 ng/ml (PDR), with a significant difference between healthy and patients without retinopathy (p = .03), between no retinopathy and NPDR (p = .001), and between NPDR and PDR (p < .0001). E selectin was increased in correlation with severity of the retinopathy, with a significant difference between groups of patients (p = .03 between healthy subjects and T2DM patients without retinopathy, p = .001 between patients with T2DM no retinopathy and NPDR, p < .0001 between NPDR and PDR).

CONCLUSIONS

We found a significant increase in levels of adhesion molecules (VCAM-1) and selectins (E-selectin) in parallel with increased severity of diabetic retinopathy, with a significant difference of inflammatory markers between stages of retinopathy.

Effects of omega-3 PUFA on immune markers in adolescent individuals at ultra-high risk for psychosis - Results of the randomized controlled Vienna omega-3 study

Alterations of immune function have been reported in ultra-high risk (UHR) for psychosis patients causing expectations in terms of predictive meaningfulness and benefits of anti-inflammatory agents. According to a RCT in UHR-patients supplementation of omega-3 polyunsaturated fatty acids (PUFA) was effective in reducing transition to psychosis risk and to improve symptomatology. Based on preclinical findings, we now investigated state marker properties of and the influence of PUFA on immune markers in a RCT (clinical trials.gov Identifier: NCT00396643). In a longitudinal design we measured plasma levels of the pro-inflammatory interleukin 6 (IL-6), the soluble alpha (Tac) subunit of the interleukin 2 receptor (sIL-2r), and the circulating soluble form of the intercellular adhesion molecule one (sICAM-1), in 79 help-seeking UHR individuals (13-25years of age). Using linear mixed model (LMM) analysis, we investigated the effects of 12weeks supplementation of either 1.2g/d PUFA (n=38) or Placebo (n=41). At baseline, inflammatory markers were not altered in patients who later suffered transition to psychosis within one year (n=12; 11 PUFA-group, 1 PL-group). IL-6 was weakly inverse associated with omega-6 PUFA, and highly increased in nicotine users. In univariate tests of the LMM omega-3 PUFA caused a significant increase of sICAM-1 (p=0.022). PUFA did not significantly influence IL-6 or sIL-2r. The enhancement of sICAM-1 in the PUFA condition is suggestive for supportive effects on vascular immune response and immediate Th1 helper cell mediated immune answer, which was found disturbed in manifest schizophrenia, e.g. by facilitating the leukocyte adhesion and migration across the endothelium.

Evaluation of Coagulation Profile in Children with Type 1 Diabetes Mellitus Using Rotational Thromboelastometry

The prothrombotic state in type 1 diabetes mellitus (T1DM) has been reported as a plausible cause of vascular complications. Rotational thromboelastometry (ROTEM) assay enables the global assessment of coagulation status. This study aimed to assess hypercoagulability in children with T1DM using ROTEM. A total of 43 T1DM children (20 females and 23 males) aged 2-18 years and age- and sex-matched 30 healthy control subjects were enrolled in the study group. ROTEM assays [intrinsic TEM (INTEM) and extrinsic TEM (EXTEM)] were used to measure and analyze coagulation time (CT), clot formation time, maximum clot firmness (MCF). Glycated hemoglobin levels (HbA1c), diabetic complications, platelet count, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, and dimerized plasmin fragment D (D-dimer) were determined in the study group. The mean duration of T1DM diagnosis was 3.15 ± 2.49 years, and the mean HbA1c level was 8.94 ± 1.88% (74.29 ± 20.59 mmol/mol). None of the patients had macrovascular complications. Nephropathy was present in five patients. In the T1DM group, EXTEM-CT [80.00 (66.75-108.50)] was significantly lower, and EXTEM-MCF [65.00 (64.00-70.00)] and INTEM-MCF [65.00 (62.00-68.00)] were significantly higher than in the controls (p < 0.001, p = 0.026, and p = 0.004, respectively). However, the duration of T1DM and the degree of metabolic control had no influence on these parameters. Platelet count, PT, aPTT, fibrinogen and D-dimer levels were comparable between the diabetic patients and the control group. There were statistically significant correlations between fibrinogen level and INTEM-MCF and EXTEM-MCF (p < 0.001, p = 0.002 and r = 0.545, r = 0.454, respectively) This study shows that decreased levels of CT and increased levels of MCF suggest hypercoagulability in patients with T1DM. Further studies are needed to confirm our findings on a larger number of diabetic patients.

C-peptide antioxidant adaptive pathways in β cells and diabetes

In this review, we present findings that support autocrine cell protection by C-peptide in the context of clinical studies of type 1 diabetes (T1D), which universally measure C-peptide serum levels as a surrogate for β cell functional mass. Over the last decade, evidence has accumulated that supports models in which C-peptide, cosecreted with insulin by pancreatic β cells, acts on peripheral targets including the vascular endothelium to reduce oxidative stress and apoptosis subsequent to exposure to diabetic insults. In parallel, as assays have become more sensitive, C-peptide has been detected in the circulation of most subjects with T1D where higher C-peptide levels are associated with fewer and slower development of diabetic microvascular complications, consistent with antioxidant protection by C-peptide. Clinical trials investigating C-peptide-replacement therapy effects have demonstrated amelioration of T1D nephropathy and neuropathy. Recently, the antioxidant action of C-peptide was extended to the β cells secreting it, that is an autocrine mechanism. Autocrine protection has major implications for the treatment of diabetes because the more C-peptide secreted, the more protection provided to the same β cells resulting in a slower decay in β cell functional mass over the time course of disease. Why β cells evolved to cosecrete an antioxidant C-peptide hormone together with the glycaemia-lowering insulin hormone is explored in the context of proposed evolutionary advantages of physiologically transient oxidative stress and insulin resistance as an adaptation for survival through times of fuel scarcity. The importance of recognizing autocrine C-peptide protection of functional β cell mass in observational clinical studies, and its therapeutic implications in interventional C-peptide-replacement studies, will be discussed.

The Role of Oxidative Stress in Diabetic Neuropathy: Generation of Free Radical Species in the Glycation Reaction and Gene Polymorphisms Encoding Antioxidant Enzymes to Genetic Susceptibility to Diabetic Neuropathy in Population of Type I Diabetic Patients

Diabetic neuropathy (DN) represents the main cause of morbidity and mortality among diabetic patients. Clinical data support the conclusion that the severity of DN is related to the frequency and duration of hyperglycemic periods. The presented experimental and clinical evidences propose that changes in cellular function resulting in oxidative stress act as a leading factor in the development and progression of DN. Hyperglycemia- and dyslipidemia-driven oxidative stress is a major contributor, enhanced by advanced glycation end product (AGE) formation and polyol pathway activation. There are several polymorphous pathways that lead to oxidative stress in the peripheral nervous system in chronic hyperglycemia. This article demonstrates the origin of oxidative stress derived from glycation reactions and genetic variations within the antioxidant genes which could be implicated in the pathogenesis of DN. In the diabetic state, unchecked superoxide accumulation and resultant increases in polyol pathway activity, AGEs accumulation, protein kinase C activity, and hexosamine flux trigger a feed-forward system of progressive cellular dysfunction. In nerve, this confluence of metabolic and vascular disturbances leads to impaired neural function and loss of neurotrophic support, and over the long term, can mediate apoptosis of neurons and Schwann cells, the glial cells of the peripheral nervous system. In this article, we consider AGE-mediated reactive oxygen species (ROS) generation as a pathogenesis factor in the development of DN. It is likely that oxidative modification of proteins and other biomolecules might be the consequence of local generation of superoxide on the interaction of the residues of L-lysine (and probably other amino acids) with α-ketoaldehydes. This phenomenon of non-enzymatic superoxide generation might be an element of autocatalytic intensification of pathophysiological action of carbonyl stress. Glyoxal and methylglyoxal formed during metabolic pathway are detoxified by the glyoxalase system with reduced glutathione as co-factor. The concentration of reduced glutathione may be decreased by oxidative stress and by decreased in situ glutathione reductase activity in diabetes mellitus. Genetic variations within the antioxidant genes therefore could be implicated in the pathogenesis of DN. In this work, the supporting data about the association between the -262T > C polymorphism of the catalase (CAT) gene and DN were shown. The -262TT genotype of the CAT gene was significantly associated with higher erythrocyte catalase activity in blood of DN patients compared to the -262CC genotype (17.8 ± 2.7 × 10(4) IU/g Hb vs. 13.5 ± 3.2 × 10(4) IU/g Hb, P = 0.0022). The role of these factors in the development of diabetic complications and the prospective prevention of DN by supplementation in formulations of transglycating imidazole-containing peptide-based antioxidants (non-hydrolyzed carnosine, carcinine, n-acetylcarcinine) scavenging ROS in the glycation reaction, modifying the activity of enzymic and non-enzymic antioxidant defenses that participate in metabolic processes with ability of controlling at transcriptional levels the differential expression of several genes encoding antioxidant enzymes inherent to DN in Type I Diabetic patients, now deserve investigation.

Glycemic variability predicts inflammation in adolescents with type 1 diabetes

BACKGROUND

Adolescents with type 1 diabetes (T1D) have increased risk of cardiovascular disease as well as elevations in biomarkers of systemic inflammation, plasma protein oxidation and vascular endothelial injury. It is unclear whether hyperglycemia itself, or variations in blood glucose are predictors of these abnormalities.

METHODS

This study was designed to determine the relationship of inflammatory (C-reactive protein, CRP), oxidative (total anti-oxidative capacity, TAOC) and endothelial injury (soluble intracellular adhesion molecule 1, sICAM1) markers to glycemic control measures from 3 days of continuous glucose monitoring (CGM) and to hemoglobin A1c (HbA1c), and HbA1c×duration area under the curve (A1cDur).

RESULTS

Seventeen adolescents (8 F/9M; age, 13.1±1.6 years (mean±SD); duration, 4.8±3.8 years, BMI, 20.3±3.1 kg/m2; A1c, 8.3±1.2%) were studied. Log CRP but was not related to age, duration, body mass index (BMI), HbA1c, or A1cDUR. TAOC increased as logA1cDUR increased (n=13, r=0.61, p=0.028). CRP and sICAM were not related to CGM average glucose but log CRP increased as 3 day glucose standard deviation increased (r=0.66, p=0.006). TAOC increased as glucose standard deviation increased (r=0.63, p=0.028).

CONCLUSIONS

Increased glucose variability is associated with increased inflammation in adolescents withT1D. Increased TAOC with increasing variability may be an effort to compensate for the ongoing oxidative stress.

Review: Targeting therapeutics against glutathione depletion in diabetes and its complications

Glutathione (GSH) is the most abundant intracellular antioxidant, the dysregulation of which is widely implicated in disease states. There is in vitro and clinical evidence that abnormal glutathione status is involved in β-cell dysfunction and in the pathogenesis of long-term complications of diabetes. Interest has developed in the potential for therapeutic modification of glutathione status in the treatment of diabetes. There is evidence which supports the use of glutathione pro-drugs, lipoic acid and vitamin supplementation but further studies are required before these enter widespread use. Studies into the role of oxidative stress in diabetes rely heavily on the ability to measure glutathione, which has been a problematic analyte to measure in the laboratory. New electrochemical methods being developed should speed up the rate at which data can be accumulated and will help define clinical utility for its measurement.

Review: Endothelial dysfunction and pre-symptomatic atherosclerosis in type 1 diabetes — pathogenesis and identification

The vascular endothelium offers an attractive model for detecting functional abnormalities prior to structural changes in the vasculature. Demonstration of progression from endothelial dysfunction through to atherosclerosis is required. Measurements of forearm bloodflow, biochemical markers and biophysical assessments of the endothelium have been employed as research tools for investigating pre-symptomatic atherosclerosis.

However, studies examining endothelial function in type 1 diabetes have been sparse and conflicting. Differences in methodology and the study populations were potential confounding factors. Augmented vasodilatory prostanoids compensate for reduced nitric oxide bioavailability in determining endothelial function in type 1 diabetes. Hyperglycaemia appears to be the initiating event in type 1 diabetes which promotes a variety of biochemical events which are pathogenic to the endothelium.

Improved understanding of the endothelium may facilitate the development of novel diagnostic tools and interventions targeting the accelerated atherosclerosis associated with type 1 diabetes.

Review: Diabetes as a procoagulant condition

Major known effects of the metabolic derangements of diabetes in haemostasis are induction of platelet-vascular activation by hyperglycaemia, the increase in fibrinogen, modification of fibrin substrate by glucose and hypofibrinolysis related to insulin resistance. The platelet effects are specifically expressed during high shear stress and may be relevant in particular for developing of micro-angiopathy. Hypofibrinolysis, increased fibrinogen and modifications of fibrin may aggravate microthrombosis and organ damage and contribute to precipitation of coronary and cerebral infarction. In addition to specific anti-diabetic medication to reduce the haemostatic effects, specific antiplatelet and profibrinolytic treatments may be relevant for reducing further the morbidity and mortality in diabetics for both micro- and macro-angiopathy.

Microvascular Changes in the Diabetic Foot

Impairment of the microcirculation of diabetic patients may contribute to secondary complications in the lower extremity, such as foot infections and ulcerations. These microcirculatory changes, which are mainly functional rather than structural, are responsible for the impaired ability of the microvasculature to vasodilate in response to injury. Dysfunction of vascular endothelial cells and vascular smooth muscle cells both contribute to the reduction in vasodilation that is observed in diabetic patients. Nerve-axon reflex related microvascular vasodilation is also impaired in the diabetic population, and there is a growing belief that both the failure of the vessels to dilate and the impairment of the nerve axon reflex are major causes for impaired wound healing in diabetic patients. Further studies are necessary to clarify the precise etiology of endothelial and smooth muscle dysfunction in diabetic patients so that potential therapeutic interventions may be identified.

Nanoceria Attenuated High Glucose-Induced Oxidative Damage in HepG2 Cells

Objective

Hyperglycemia, a common metabolic disorder in diabetes, can lead to oxidative damage. The use of antioxidants can benefit the control and prevention of diabetes side effects. This study aims to evaluate the effect of nanoceria particles, as an antioxidant, on glucose induced cytotoxicity, reactive oxygen species (ROS), lipid peroxidation (LPO) and glutathione (GSH) content in a human hepatocellular liver carcinoma cell line (HepG2) cell line.

Materials and Methods

In this experimental study, we divided HepG2 cells into these groups: i. Cells treated with 5 mM D-glucose (control), ii. Cells treated with 45 mM D- mannitol+5 mM D-glucose (osmotic control), iii. Cells treated with 50 mM D-glucose (high glucose), and iv. Cells treated with 50 mM D-glucose+nanoceria. Cell viability, ROS formation, LPO and GSH were measured and analyzed statistically.

Results

High glucose (50 mM) treatment caused significant cell death and increased oxidative stress markers in HepG2 cells. Interestingly, nanoceria at a concentration of 50 mM significantly decreased the high glucose-induced cytotoxicity, ROS formation and LPO. This concentration of nanoceria increased the GSH content in HepG2 cells (P<0.05).

Conclusion

The antioxidant feature of nanoceria particles makes it an attractive candidate for attenuation of hyperglycemia oxidative damage in different organs.

Suboptimal glycaemic control enhances the risk of impaired prothrombotic state in youths with type 1 diabetes mellitus

OBJECTIVE

To estimate markers of prothrombotic state and endothelial dysfunction in youths with type 1 diabetes mellitus (T1DM) and investigate possible associations with anthropometric/demographic data, glycaemic control and lipid profile.

METHODS

In a cross-sectional design, we recruited 155 youths with T1DM and determined levels of plasminogen activator inhibitor-1-antigen (PAI-1-Ag), von Willebrand factor-antigen (vWF-Ag), fibrinogen (FB), lipids and glycosylated haemoglobin (HbA1c).

RESULTS

Of all the participants, 76 (49%) had increased levels of at least one of prothrombotic factors. Suboptimal glycaemic control was associated with a worse lipid profile and an eightfold increased risk of elevated vWF-Ag levels. Higher vWF-Ag concentrations were also correlated with impaired lipid profile and increased HbA1c values, whereas PAI-1-Ag was positively correlated only with triglyceride levels. After adjustment for potential confounders, only HbA1c contributed independently to the variation in vWF-Ag levels.

CONCLUSION

Impaired prothrombotic state and consequently endothelial dysfunction are present in youths with T1DM, representing a cumulative risk factor for future cardiovascular disease (CVD). Achievement and maintenance of euglycaemia and normolipidaemia are crucial to decelerate progress of this process.

Early microvascular changes with loss of the glycocalyx in children with type 1 diabetes

OBJECTIVE

To evaluate the microcirculation of children with type 1 diabetes mellitus who demonstrate no clinical signs of diabetic microangiopathy for the presence of microvascular alterations and glycocalyx perturbation.

STUDY DESIGN

Images of sublingual vessels were obtained in 14 children with diabetes (ages 12.8 ± 2.8 years, diabetes duration 6.7 ± 4.3 years) and 14 control patients (ages 11.8 ± 2.8 years) by the use of sidestream dark field imaging and analyzed for total vessel density, vessel surface coverage, vessel diameter distribution, mean flow index, and glycocalyx thickness. Wilcoxon rank sum test and Pearson correlation were used for statistical analysis.

RESULTS

We observed profound microcirculatory changes in children with diabetes compared with control patients, with a significant reduction of glycocalyx thickness (0.38 μm vs 0.60 μm; P = .013), which was inversely correlated with blood glucose levels (r = -0.55; P = .003). Furthermore, the percentage of large vessels (>20 μm diameter) was significantly increased (11% vs 6%; P = .023) at the expense of capillaries (<10 μm diameter) with consequent increase in total vessel surface coverage (30% vs 26.0%; P = .041). No differences were seen in total vessel density and mean flow index.

CONCLUSIONS

Microvascular alterations, including changes in microvessel distribution and loss of the glycocalyx, can be detected in children with type 1 diabetes mellitus before clinically apparent vascular complications. Our results disclose the glycocalyx as a possible monitoring measurement for earlier detection of diabetic microangiopathy and may provide a basis for new therapeutic strategies aiming at protection or restoration of the glycocalyx.

Does metformin improve vascular health in children with type 1 diabetes? Protocol for a one year, double blind, randomised, placebo controlled trial

BACKGROUND

Cardiovascular disease is the leading cause of mortality in Type 1 diabetes (T1D). Vascular dysfunction is an early and critical event in the development of cardiovascular disease. Children with T1D have vascular dysfunction therefore early interventions to improve vascular health are essential to reduce cardiovascular mortality in T1D. Metformin is an insulin sensitising agent which is known to improve vascular health outcomes in type 2 diabetes (T2D) and other individuals with insulin resistance. It has been used safely in children and adolescents with T2D for over 10 years. This study aims to assess the effect of metformin on vascular health in children with T1D.

METHODS/DESIGN

This study is a 12 month, double blind, randomised, placebo controlled trial to determine the effect of metformin on vascular health in children (age 8-18) with T1D. The sample size is 76 with 38 children in the metformin group and 38 children in the placebo group. Vascular health and biochemical markers will be measured at baseline, 3, 6 and 12 months. Vascular function will be measured using flow mediated dilatation and glyceryl trinitrate mediated dilatation of the brachial artery and vascular structure will be measured with carotid and aortic intima media thickness, using standardised protocols.

DISCUSSION

This study will be the first to investigate the effect of metformin on vascular health in children with T1D. It will provide important information on a potential intervention to improve cardiovascular morbidity and mortality in this population at high risk from cardiovascular disease.

TRIAL REGISTRATION

Australia New Zealand Clinical Trials Registry ACTRN12611000148976.

Can C-peptide mediated anti-inflammatory effects retard the development of microvascular complications of type 1 diabetes?

Hyperglycemia is considered to be the major cause of microvascular complications of diabetes. Growing evidence highlights the importance of hyperglycemia-mediated inflammation in the initiation and progression of microvascular complications in type 1 diabetes. We hypothesize that lack of proinsulin C-peptide and lack of its anti-inflammatory properties contribute to the development of microvascular complications. Evidence gathered over the past 20 years shows that C-peptide is a biologically active peptide in its own right. It has been shown to reduce formation of reactive oxygen species and nuclear factor-κB activation induced by hyperglycemia, resulting in inhibition of cytokine, chemokine and cell adhesion molecule formation as well as reduced apoptotic activity. In addition, C-peptide stimulates and induces the expression of both Na⁺, K⁺-ATPase and endothelial nitric oxide synthase. Animal studies and small-scale clinical trials in type 1 diabetes patients suggest that C-peptide replacement combined with regular insulin therapy exerts beneficial effects on kidney and nerve dysfunction. Further clinical trials in patients with microvascular complications including measurements of inflammatory markers are warranted to explore the clinical significance of the aforementioned, previously unrecognized, C-peptide effects.

The a1/a2 polymorphism of the glycoprotein IIIa gene and myocardial infarction in Caucasians with type 2 diabetes

A PlA1/A2 polymorphism of glycoprotein IIIa is known to be involved in the pathogenesis of coronary artery disease (CAD) and myocardial infarction (MI). The aim of this study was to investigate an association between the PlA1/A2 polymorphism of the glycoprotein IIIa gene and the risk of MI in Caucasians with type 2 diabetes. 549 Caucasians with type 2 diabetes were enrolled in the cross sectional retrospective case-control study: 224 patients with MI and 325 diabetic subjects without CAD. Blood biochemical analysis was performed. The polymerase chain reaction with restriction fragment length polymorphism was used for genetic analysis. Patients with MI were older (62 ± 11.8 vs. 58.5 ± 11.6 years; P < 0.001), and had a longer duration of type 2 diabetes (17.6 ± 8.9 vs. 15.1 ± 9.2; P = 0.01) compared to the diabetics without CAD. A significant difference in distribution of the A2A2 genotype of glycoprotein IIIa was not found between 224 diabetic patients with MI in comparison to 325 diabetics without CAD (11.6 vs. 14,1 %; n.s.). The diabetes duration and male sex were independent factors for the development of MI, whereas the PlA1/A2 polymorphism of glycoprotein IIIa was not. To conclude, The A2A2 genotype of the glycoprotein IIIa polymorphism was not associated with MI risk in Caucasians with type 2 diabetes.

All glutathione forms are depleted in blood of obese and type 1 diabetic children

BACKGROUND

Oxidative stress plays an important role in the pathogenesis of type 1 diabetes (T1D), where an increase in reactive oxygen species may contribute to the initial destruction of β-cells. Accumulating evidence also suggests a role for oxidative stress in obesity, where it may potentiate the development of complications.

OBJECTIVE

To analyze the in vivo homeostasis of glutathione in children with T1D at onset and in children who are obese, to evaluate the systemic content of all glutathione forms (total, reduced, oxidized, and protein-bound glutathione) and the balance among them. Moreover, since glutathione bound to hemoglobin is a clinical marker of oxidative stress in human blood, we analyzed glutathionyl-hemoglobin in T1D and in obese children.

SUBJECTS

Children with T1D at onset (n = 30) or obesity (n = 30) at the first observation, and 30 healthy subjects chosen from the children who attended the outpatient clinic for minor problems.

METHODS

We assessed circulating levels of various glutathione forms by performing reverse-phase high performance liquid chromatography. Glutathionyl-hemoglobin analysis was carried out by cation-exchange chromatography.

RESULTS

In children with T1D and in obese children, we found a significant decrease of all glutathione forms including, for the first time, the content of total glutathione and glutathionylated proteins. The comparison among forms shows no significant imbalance in T1D patients, whereas in obese children it seems to suggest an attempt to rebalance the glutathione system homeostasis.

CONCLUSIONS

Our findings consistently show in vivo evidence of glutathione depletion upon early onset of T1D and in obese children, thus evidencing glutathione as an early marker in these two metabolic conditions.

Elevated E-selectin and diastolic blood pressure in diabetic children

BACKGROUND

Cardiovascular risk markers are related to micro-angiopathy in children with type 1 diabetes (T1DM), but there is no information about their relationship with blood pressure (BP) and endothelial function.

MATERIALS AND METHODS

This was a case-control study including 29 children with T1DM (mean age 10·5 ± 2·7 years, disease duration: 3·8 ± 2·2 years) and 39 healthy controls (mean age: 9·8 ± 2·7 years). We assessed 24-h ambulatory BP, vascular function and serum level of lipids, vascular cell adhesion molecule-1 (VCAM-1; ICAM) and selectins (E-selectin; P-selectin).

RESULTS

The subject groups had similar physical characteristics and lipids level, except body mass index (BMI) which was higher in T1DM than in healthy children (18·6 ± 2·6 vs. 16·7 ± 2·5 kg/m(2), P = 0·003). Children with T1DM had increased 24 h diastolic BP z-score (0·62 ± 0·9 vs. -0·65 ± 0·8, P < 0·001), even after adjustment for BMI, as well as higher VCAM-1 concentration (492 ± 346 vs. 340 ± 225 ng/mL, P = 0·039) compared to healthy subjects. Diastolic BP z-scores were associated with disease duration, E-selectin and triglyceride levels in the T1DM group (P < 0·05). E-selectin was also related to triglycerides, otherwise there were no relationships between vascular function, markers and BP.

CONCLUSION

E-selectin, an early atherosclerosis biomarker, is positively associated with diastolic BP values in children with T1DM, despite relatively short disease duration.

Type 1 diabetes mellitus and major depressive disorder: evidence for a biological link

AIMS/HYPOTHESIS

A growing body of research suggests that the prevalence of major depressive disorder (MDD) in children and youth with type 1 diabetes mellitus is significantly higher than that of youth without type 1 diabetes and is associated with increased illness severity. The objective of this article is to review the current literature on the pathophysiology of these two common diseases with respect to potential areas of overlapping biological dysfunction.

METHODS

A search of English language articles published between 1966 and 2010 was conducted and augmented with manual review of reference lists from the identified publications.

RESULTS

The evidence suggests plausible mechanisms whereby a biological relationship between type 1 diabetes and MDD may exist. These include the effects of circulating cytokines associated with autoimmune diabetes, the direct impact of insulin deficiency on neurogenesis/neurotransmitter metabolism, the effects of the chronic hyperglycaemic state, occurrence of iatrogenic hypoglycaemia and the impact of basal hyperactivity of the hypothalamic-pituitary-adrenal axis.

CONCLUSIONS/INTERPRETATION

Shared biological vulnerabilities may be implicated in the comorbidity of type 1 diabetes and MDD. Further research is warranted to determine the magnitude of associations and confirm their observation in clinical populations.

A1/A2 polymorphism of the glycoprotein IIIa gene and diabetic retinopathy in Caucasians with type 2 diabetes

BACKGROUND

A PlA1/A2 polymorphism of glycoprotein IIIa is known to be involved in the pathogenesis of arterial thrombosis, myocardial infarction, stroke and type 2 diabetes, but there is no evidence of association with diabetic retinopathy. The aim of this study was to examine the role of the PlA1/A2 polymorphism of the glycoprotein IIIa gene in the development of diabetic retinopathy in Caucasians with type 2 diabetes.

DESIGN

Cross-sectional case-control study.

PARTICIPANTS

Totally 222 patients with diabetic retinopathy and 120 diabetic subjects without clinical signs of diabetic retinopathy from the Eye Clinic, University Medical Centre Ljubljana were enrolled in the study.

METHODS

Fundus examination and blood biochemical analysis were performed. The polymerase chain reaction and restriction fragment length polymorphism were used.

MAIN OUTCOME MEASURES

The total cholesterol, triglyceride, high-density lipoprotein levels, fasting blood glucose and HbA(1c) were measured, and the genotypes of the PlA1/A2 polymorphism were determined.

RESULTS

Patients with diabetic retinopathy had earlier onset, longer duration of type 2 diabetes and a higher incidence of insulin therapy compared to the diabetic patients without diabetic retinopathy. A significantly lower frequency of the A2A2 genotype of glycoprotein IIIa was found in diabetic patients with retinopathy compared to those without retinopathy (odds ratio = 0.49, 95% confidence interval = 0.28-0.89; P = 0.018).

CONCLUSIONS

The A2A2 genotype of the glycoprotein IIIa polymorphism was associated with lower risk for diabetic retinopathy in Caucasians with type 2 diabetes. Further studies are needed to elucidate its protective role in the development of diabetic retinopathy in Caucasians.

Biochemical indices of vascular function, glucose metabolism and oxidative stress in horses with equine Cushing's disease

REASONS FOR PERFORMING STUDY

The mechanisms underlying the increased risk of laminitis in horses with equine Cushing's disease (ECD) are poorly understood.

HYPOTHESIS

That abnormalities in glucose homeostasis, similar to those which cause microvascular dysfunction in human diabetics, contribute to development of laminitis in horses with ECD.

METHODS

Thirty-one aged horses were divided into 3 groups based on clinical signs and dexamethasone suppression testing (DST). Group 1 (n = 12) had clinical ECD as evidenced by hirsutism. Group 2 (n = 10) had a positive DST but no hirsutism. Group 3 (n = 9) were controls without ECD, with a negative DST and no clinical evidence of ECD. Biochemical indices of glucose metabolism, vascular function and oxidative stress were determined in single morning blood samples.

RESULTS

Group 1 had abnormalities in glucose homeostasis, including increased levels of glucose and insulin, compared to Groups 2 and 3. Groups 1 and 2 had significantly lower plasma thiol (PSH) levels and nonsignificantly lower albumin-corrected PSH levels than Group 3, consistent with oxidative stress.

CONCLUSIONS AND POTENTIAL RELEVANCE

The observed abnormalities in glucose metabolism and oxidative stress could potentially contribute to development of laminitis in horses with ECD, by similar mechanisms to those that cause microvascular dysfunction in human diabetics. The absence of inter-group differences in the biochemical indices of vascular function precludes their use as preclinical diagnostic indicators of vascular dysfunction. The study also highlighted limitations in the premortem diagnosis of ECD.

Anti-inflammatory properties of C-Peptide

C-peptide, historically considered a biologically inactive peptide, has been shown to exert insulin-independent biological effects on a number of cells proving itself as a bioactive peptide with anti-inflammatory properties. Type 1 diabetic patients typically lack C-peptide, and are at increased risk of developing both micro- and macrovascular complications, which account for significant morbidity and mortality in this population. Inflammatory mechanisms play a pivotal role in vascular disease. Inflammation and hyperglycemia are major components in the development of vascular dysfunction in type 1 diabetes. The anti-inflammatory properties of C-peptide discovered to date are at the level of the vascular endothelium, and vascular smooth muscle cells exposed to a variety of insults. Additionally, C-peptide has shown anti-inflammatory properties in models of endotoxic shock and type 1 diabetes-associated encephalopathy. Given the anti-inflammatory properties of C-peptide, one may speculate dual hormone replacement therapy with both insulin and C-peptide in patients with type 1 diabetes may be warranted in the future to decrease morbidity and mortality in this population.

Microvascular dysfunction in diabetic foot disease and ulceration

Diabetic foot disease and ulceration is a major complication that may lead to the amputation of the lower limbs. Microangiopathy may play a significant role in the pathogenesis of tissue breakdown in the diabetic foot. However, the precise mechanisms of this process remain unclear and poorly understood. Microvasculature in the skin is comprised of nutritive capillaries and thermoregulatory arteriovenous shunt flow. It is regulated through the complex interaction of neurogenic and neurovascular control. The interplay among endothelial dysfunction, impaired nerve axon reflex activities, and microvascular regulation in the diabetic patient results in the poor healing of wounds. Skin microvasculature undergoes both morphologic changes as well as functional deficits when parts of the body come under stress or injury. Two important theories that have been put forward to explain the abnormalities that have been observed are the haemodynamic hypothesis and capillary steal syndrome. With advances in medical technology, microvasculature can now be measured quantitatively. This article reviews the development of microvascular dysfunction in the diabetic foot and discusses how it may relate to the pathogenesis of diabetic foot problems and ulceration. Common methods for measuring skin microcirculation are also discussed.

Human C-peptide antagonises high glucose-induced endothelial dysfunction through the nuclear factor-kappaB pathway

AIMS/HYPOTHESIS

Endothelial dysfunction in diabetes is predominantly caused by hyperglycaemia leading to vascular complications through overproduction of oxidative stress and activation of the transcription factor nuclear factor-kappaB (NF-kappaB). Many studies have suggested that decreased circulating levels of C-peptide may play a role in diabetic vascular dysfunction. To date, the possible effects of C-peptide on endothelial cells and intracellular signalling pathways are largely unknown. We therefore investigated the effect of C-peptide on several biochemical markers of endothelial dysfunction in vitro. To gain insights into potential intracellular signalling pathways affected by C-peptide, we tested NF-kappaB activation, since it is known that inflammation, secondary to oxidative stress, is a key component of vascular complications and NF-kappaB is a redox-dependent transcription factor.

METHODS

Human aortic endothelial cells (HAEC) were exposed to 25 mmol/l glucose in the presence of C-peptide (0.5 nmol/l) for 24 h and tested for expression of the gene encoding vascular cell adhesion molecule-1 (VCAM-1) by RT-PCR and flow cytometry. Secretion of IL-8 and monocyte chemoattractant protein-1 (MCP-1) was measured by ELISA. NF-kappaB activation was analysed by immunoblotting and ELISA.

RESULTS

Physiological concentrations of C-peptide affect high glucose-induced endothelial dysfunction by: (1) decreasing VCAM-1 expression and U-937 cell adherence to HAEC; (2) reducing secretion of IL-8 and MCP-1; and (3) suppressing NF-kappaB activation.

CONCLUSIONS/INTERPRETATION

During hyperglycaemia, C-peptide directly affects VCAM-1 expression and both MCP-1 and IL-8 HAEC secretion by reducing NF-kappaB activation. These effects suggest a physiological anti-inflammatory (and potentially anti-atherogenic) activity of C-peptide on endothelial cells.

Molecular mechanisms and potential clinical significance of S-glutathionylation

Protein S-glutathionylation, the reversible binding of glutathione to protein thiols (PSH), is involved in protein redox regulation, storage of glutathione, and protection of PSH from irreversible oxidation. S-Glutathionylated protein (PSSG) can result from thiol/disulfide exchange between PSH and GSSG or PSSG; direct interaction between partially oxidized PSH and GSH; reactions between PSH and S-nitrosothiols, oxidized forms of GSH, or glutathione thiyl radical. Indeed, thiol/disulfide exchange is an unlikely intracellular mechanism for S-glutathionylation, because of the redox potential of most Cys residues and the GSSG export by most cells as a protective mechanism against oxidative stress. S-Glutathionylation can be reversed, following restoration of a reducing GSH/GSSG ratio, in an enzyme-dependent or -independent manner. Currently, definite evidence of protein S-glutathionylation has been clearly demonstrated in few human diseases. In aging human lenses, protein S-glutathionylation increases; during cataractogenesis, some of lens proteins, including alpha- and beta-crystallins, form both mixed disulfides and disulfide-cross-linked aggregates, which increase with cataract severity. The correlation of lens nuclear color and opalescence intensity with protein S-glutathionylation indicates that protein-thiol mixed disulfides may play an important role in cataractogenesis and development of brunescence in human lenses. Recently, specific PSSG have been identified in the inferior parietal lobule in Alzheimer's disease. However, much investigation is needed to clarify the actual involvement of protein S-glutathionylation in many human diseases.

Intensive insulin therapy improves endothelial function and microvascular reactivity in young people with type 1 diabetes

AIMS/HYPOTHESIS

Macrovascular disease is an important cause of the increased morbidity and mortality rates associated with type 1 diabetes, and this vascular impairment begins in childhood. The aim of this study was to determine whether introducing intensive diabetes management [intensive insulin therapy (IIT) and 'Sweet Talk' text-messaging support] produces measurable improvements in endothelial function.

METHODS

One hundred and twenty-six patients fulfilled the eligibility criteria (type 1 diabetes for >1 year; on conventional insulin therapy (CIT); aged between 8 and 18 years), of whom 92 enrolled. Patients were randomised to group 1, CIT only (n=28); group 2, CIT and Sweet Talk (n=33); or group 3, IIT and Sweet Talk (n=31). Vascular assessments (including measures of endothelial damage, activation, dysfunction and oxidative stress) and HbA1c were performed at baseline and repeated after 12 months of the study.

RESULTS

Glycaemic control deteriorated in patients on CIT, but improved significantly in patients allocated to IIT (p=0.007). IIT was associated with significantly greater improvements in E-selectin (p<0.0001) than CIT (group 1, p=0.026 and group 2, p=0.053). Vascular responses to acetylcholine improved in patients on IIT (p=0.017), but not in patients receiving CIT. These changes were all independent of HbA1c level.

CONCLUSIONS/INTERPRETATION

IIT appears to be associated with improvements in vascular markers, independently of changes in HbA1c, suggesting that IIT may confer vascular protection in addition to improving glycaemic control.

Acute hyperglycaemia induces an inflammatory response in young patients with type 1 diabetes

BACKGROUND

Patients with type 1 diabetes (T1D) are at a substantially increased risk of cardiovascular disease. Stress-induced hyperglycaemia in turn is shown to worsen the prognosis of patients suffering from an acute myocardial infarction. However, the mechanisms behind these findings are incompletely known.

AIM

To investigate whether markers of chronic inflammation, and oxidative stress respond to acute hyperglycaemia in patients with T1D.

METHODS

The plasma glucose concentration was rapidly raised from 5 to 15 mmol/L in 35 males (22 men with T1D and 13 age-matched non-diabetic volunteers) and maintained for 2 h. All participants were young non-smokers without any signs of diabetic or other complications. Markers of chronic inflammation, and oxidative stress were analysed in serum/plasma samples drawn at base-line and after 120 min of hyperglycaemia.

RESULTS

Compared to normoglycaemia, acute hyperglycaemia increased the interleukin (IL)-6 concentrations by 39% in patients with T1D (P<0.01) and 26% in healthy volunteers (P<0.05). During hyperglycaemia the superoxide dismutase concentration was increased by 17% in the healthy volunteers (P<0.01) and 5% in the patients with type 1 diabetes (P=NS). The increase in tumour necrosis factor (TNF)-alpha was larger in patients with type 1 diabetes than in non-diabetic volunteers (35% versus -10%, P<0.05).

CONCLUSIONS

This study shows that acute hyperglycaemia induces an inflammatory response in patients with type 1 diabetes.

Impact of oxidative stress on the endothelial dysfunction of children and adolescents with type 1 diabetes mellitus: protection by superoxide dismutase?

Diabetes mellitus is associated with endothelial dysfunction and oxidative stress (OS). We investigated whether these abnormalities are interrelated in children and adolescents with type 1 diabetes mellitus (T1DM) and if early OS markers predictive of vascular dysfunction can be identified. Thirty-five T1DM patients were matched for sex, age, height, and weight with nondiabetic subjects as healthy controls (CO). Flow-mediated dilatation (FMD), carotid intima media thickness (IMT), and OS status in fasting blood were measured. Diabetic children had impaired FMD (6.68+/-1.98 versus 7.92+/-1.60% in CO, p=0.004), which was more pronounced in boys. The degree of FMD impairment was not related to the lower plasma levels of antioxidants or to the higher glucose, glycation, lipids, and peroxidation products. Erythrocyte superoxide dismutase activity, copper/zinc superoxide dismutase (Cu/Zn SOD), was higher in diabetic subjects (1008+/-224 versus 845+/-195 U/g Hb in CO, p=0.003) and was positively associated with FMD. After correcting for diabetes and gender, the subgroup of children with high Cu/Zn SOD (>955 U/g Hb) had a significantly better FMD (p=0.035). These results suggest that higher circulating Cu/Zn SOD could protect T1DM children and adolescents against endothelial dysfunction. Low Cu/Zn SOD is a potential early marker of susceptibility to diabetic vascular disease.

The association of early atherosclerosis and retinopathy in adolescents with type 1 diabetes: preliminary report

Recent studies have shown a close correlation between advanced diabetic retinopathy and the late stages of atherosclerosis. The purpose of this study was to analyse the association between diabetic retinopathy and early atherosclerotic changes in adolescents with type 1 diabetes. We studied 28 adolescents with type 1 diabetes. Eight patients with nonproliferative retinopathy were compared with the remaining 20 patients, and with 11 healthy controls. The function of endothelium was assessed by measuring flow-mediated dilatation (FMD), the intima-media thickness (IMT) of the common carotid arteries and adhesion molecules (sICAM-1, sVCAM-1, sE-selectin). In the group with retinopathy FMD equalled 7.8+/-4.1% vs. 12.1+/-5.1% in the control group (p=0.04), and in the group without retinopathy, 7.6+/-5.5% (p=0.04 compared to controls). Higher IMT was found in all patients with diabetes in comparison with healthy controls: 0.49+/-0.06 mm vs. 0.42+/-0.03 mm (p=0.001). Patients with retinopathy had a significantly higher value of IMT in comparison not only with controls but also with patients without complications: 0.56+/-0.06 mm vs. 0.47+/-0.03 mm (p=0.0001). Adhesion molecule levels were not changed in patients with retinopathy. Higher IMT was found in adolescents with diabetic retinopathy in comparison with patients without complications, which may suggest that macrovascular changes are more advanced in these patients than in their diabetic peers without retinopathy.

Endothelial dysfunction, ambulatory pulse pressure and albuminuria are associated in Type 2 diabetic subjects

AIM

Elevated pulse pressure (PP) is associated with microvascular complications in Type 2 diabetic patients. In non-diabetic subjects, elevated PP has been associated with endothelial dysfunction. The relation between endothelial dysfunction and PP in diabetic subjects has not previously been examined. We examined the relation between PP, markers of endothelial activation and albuminuria in Type 2 diabetic patients.

METHODS

In 46 Type 2 diabetic patients and 19 non-diabetic subjects, we performed 24-h ambulatory blood pressure (AMBP) monitoring. Urinary albumin excretion rate was measured as three urinary albumin/creatinine ratios. Von Willebrand factor (vWF), fibrinogen, E-selectin and soluble intercellular adhesion molecule 1 (ICAM-1) were measured in plasma.

RESULTS

Thirty-four patients had normoalbuminuria (group N) and 12 had micro- or macroalbuminuria (group A). PP levels increased in a stepwise manner from the control group (group C) to group N and group A; night PP 43 +/- 5, 48 +/- 10 and 59 +/- 12 mmHg (groups C, N and A, respectively, P < 0.001). Likewise, plasma levels of vWF, fibrinogen, E-selectin and ICAM-1 increased from group C to group A; e.g. ICAM-1 [median (interquartile range)] 191 (160-217), 213 (189-262) and 316 (260-417) ng/ml, groups C, N and A, respectively, P < 0.001). In diabetic patients, night PP and plasma levels of E-selectin and ICAM-1 correlated (r = 0.38, P < 0.01 and r = 0.37, P = 0.01, night PP with E-selectin and ICAM-1, respectively).

CONCLUSION

Increased PP is associated with endothelial activation and albuminuria in Type 2 diabetic patients. Thus, endothelial dysfunction may represent a pathophysiological link between an elevated PP and microvascular complications in these subjects. Prospective studies are needed to further elucidate these associations.

Plasma methylglyoxal and glyoxal are elevated and related to early membrane alteration in young, complication-free patients with Type 1 diabetes

The reactive aldehydes methylglyoxal and glyoxal, arise from enzymatic and non-enzymatic degradation of glucose, lipid and protein catabolism, and lipid peroxidation. In Type 1 diabetes mellitus (T1DM) where hyperglycemia, oxidative stress, and lipid peroxidation are common, these aldehydes may be elevated. These aldehydes form advanced glycation end products (AGEs) with proteins that are implicated in diabetic complications. We measured plasma methylglyoxal and glyoxal in young, complication-free T1DM patients and assessed activity of the ubiquitous membrane enzyme, Na+/K+ ATPase. A total of 56 patients with TIDM (DM group), 6-22 years, and 18 non-diabetics (ND group), 6-21 years, were enrolled. Mean plasma A1C (%) was higher in the DM group (8.5+/-1.3) as compared to the ND group (5.0+/-0.3). Using a novel liquid chromatography-mass spectrophotometry method, we found that mean plasma methylglyoxal (nmol/l) and glyoxal levels (nmol/l), respectively, were higher in the DM group (841.7+/-237.7, 1051.8+/-515.2) versus the ND group (439.2+/-90.1, 328.2+/-207.5). Erythrocyte membrane Na+/K+ ATPase activity (nmol NADH oxidized/min/mg protein) was elevated in the DM group (4.47+/-0.98) compared to the ND group (2.16+/-0.59). A1C correlated with plasma methylglyoxal and glyoxal, and both aldehydes correlated with each other. A high correlation of A1C with Na+/K+ ATPase activity, and a regression analysis showing A1C as a good predictor of activity of this enzyme, point to a role for glucose in membrane alteration. In complication-free patients, increased plasma methylglyoxal, plasma glyoxal, and erythrocyte Na+/K+ ATPase activity may foretell future diabetic complications, and emphasize a need for aggressive management.

HUVECs from newborns with a strong family history of diabetes show diminished ROS synthesis in the presence of high glucose concentrations

BACKGROUND

A family history of type 2 diabetes mellitus (DM) increases the probability to develop DM and endothelial dysfunction. The probable mechanism involves augmented reactive oxygen species (ROS) synthesis. The aim of this study was to evaluate the synthesis of ROS in human umbilical vein endothelial cells (HUVECs) obtained from healthy newborns with (experimental) and without (control) a strong family history of type 2 DM, exposed to different glucose concentrations.

METHODS

HUVECs were exposed to various glucose concentrations for 24 and 48 h periods, before cell proliferation, mitochondrial activity, and mitochondrial membrane potential were determined. Intracellular ROS synthesis in the presence or absence of the mitochondrial uncoupler CCCP, cytochalasin B, or diphenyleneiodonium (DPI) was also evaluated.

RESULTS

As opposed to control HUVECs, we found that experimental HUVECs exposed to 30 mmol/L glucose showed a 50% decrease in cell proliferation, a 90% reduction in mitochondrial activity, and a statistically significant inhibition of ROS synthesis in the presence of CCCP or cytochalasin B; DPI had no effect.

CONCLUSIONS

Our results suggest that mitochondria and NAD(P)H-oxidase from HUVECs obtained from healthy newborns with a family history of DM have an innate deficient response to high glucose concentrations.

Free radicals related effects and antioxidants in saliva and serum of adolescents with Type 1 diabetes mellitus

OBJECTIVE

The purpose of the current study was to analyze both serum and salivary composition and oxidative stress markers in Type 1 diabetes mellitus (DM) patients.

DESIGN

Twenty consenting patients with DM but otherwise healthy patients aged 13-19 years and 12 healthy controls, matching in age and gender (Group 1), participated in the study. The patients were divided according to those who had controlled diabetes mellitus (Group 2) or uncontrolled diabetes mellitus (Group 3). All were analyzed for saliva composition and antioxidants. Saliva was also analyzed for its levels of superoxide dismutase (SOD) and amylase activity, total IgA and total IgG concentrations and potassium, phosphorus, magnesium and calcium electrolyte concentrations.

RESULTS

A significant correlation was found between the severity of the DM/HbA1c values and the increase in both salivary and/or serum antioxidants (peroxidase, SOD and TAS), and the various TCL parameters (H1, H3, pre-incubation and oxygenation-potential).

CONCLUSIONS

The two most important findings of the current study relate to the role of oxidative stress in the pathogenesis of Type 1 diabetes mellitus and to the involvement of salivary glands in the disease. The profound effects of DM on salivary antioxidant parameters may be also of great importance in respect to the diagnosis and evaluation of the disease. The correlation between altered salivary parameters and the severity of the disease may indicate that evaluation of the salivary status of DM patients as part of the assessment of their disease activity and severity is warranted.

Soluble vascular cell adhesion molecule-1 and soluble E-selectin are associated with micro- and macrovascular complications in Type 1 diabetic patients

OBJECTIVE

There are no large studies in Type 1 diabetic patients that have examined the relation between soluble adhesion molecules and micro- and macrovascular outcomes, although the risks of such complications are high. Therefore, the main objective is to examine the relationship between soluble (s) vascular cell adhesion molecule-1 (sVCAM-1) and sE-selectin and retinopathy, albuminuria, and cardiovascular disease (CVD) in Type 1 diabetic patients.

METHODS

Cross-sectional data on 540 Type 1 diabetic patients, with a mean age of 40 years and diabetes duration of 22 years, from the EURODIAB Prospective Complications Study (PCS) were analysed. Retinopathy was assessed by centrally graded retinal photographs. Albumin excretion rate (AER) was used to define micro- and macroalbuminuria. CVD was defined as having physician diagnosed myocardial infarction (MI), stroke, coronary artery bypass graft (CABG) or angina, or Minnesota coded ischaemic electrocardiograms (ECGs).

RESULTS

Unadjusted, there was a positive relationship between sVCAM-1 and sE-selectin with nonproliferative and proliferative retinopathy, micro- and macroalbuminuria, and CVD. After adjustment for age, sex, duration of diabetes, systolic blood pressure (BP), LDL-cholesterol, fasting triglycerides (TGs), smoking, body mass index (BMI), and glycated haemoglobin, as well as other complications, the strongest significant associations were shown between sVCAM-1 and macroalbuminuria, with an odds ratio of 1.83 (1.33-2.53) for every 100 ng/ml increase in sVCAM-1.

CONCLUSIONS

In this large sample of Type 1 diabetic patients, it was shown that sVCAM-1 and sE-selectin have positive associations with retinopathy, albuminuria, and CVD. This suggests that adhesion molecules are important in the pathogenesis of vascular complications in Type 1 diabetes.

Glutathione-s-transferase M1 and T1 polymorphisms and associations with type 1 diabetes age-at-onset

Type 1 diabetes (T1D) is an autoimmune disease characterized by pancreatic beta cell destruction involving auto-reactive T-cells, pro-inflammatory cytokines, reactive oxygen species (ROS) and loss of insulin. Monozygotic twin studies show a 20-60% concordance with T1D indicating there may be an environmental component to the disease. Glutathione (GSH) is the major endogenous antioxidant produced by the cell. GSH participates directly in the neutralization of free radicals and plays a role in the immune response. Glutathione-s-transferases (GSTs) conjugate GSH to free-radicals or xenobiotics. GST activity depletes GSH levels and may either detoxify or enhance the toxicity of a compound. Glutathione-s-transferase mu 1 (GSTM1) and glutathione-s-transferase theta 1 (GSTT1) have polymorphic homozygous deletion (null) genotypes resulting in complete absence of enzyme activity. GSTM1 and GSTT1 null genotypes in Caucasian populations have frequencies of approximately 40-60% and 15-20%, respectively. GST null genotypes have been associated with susceptibility to cancer and protection against chronic pancreatitis. The aim of this study was to investigate associations with GSTM1 and GSTT1 polymorphisms in a group T1D patients and control subjects 0-35 years old who participated in the Combined Swedish Childhood Diabetes Registry and Diabetes Incidence Study (1986-1988). Results show that the presence of the GSTM1 and not the null genotype (OR, 2.13 95% CI, 1.23-3.70, p-value, 0.007, Bonferroni corrected p-value, 0.035) may be a susceptibility factor in T1D 14-20 years old. These results suggest that the GSTM1 null genotype is associated with T1D protection and T1D age-at-onset and that susceptibility to T1D may involve GST conjugation.

Urinary oxidative stress markers in young patients with type 1 diabetes

BACKGROUND

Involvement of oxidative stress in the pathogenesis of diabetic vascular complications has been proposed. However, there are few methods to determine the status of oxidative stress both directly and quantitatively in young patients with type 1 diabetes.

METHODS

A total of 27 young patients with type 1 diabetes (mean age +/- SD, 12.6 +/- 4.2 years) with normal renal function and 38 healthy control subjects (13.0 +/- 4.6 years) were investigated. Early morning voiding urine samples were collected. The concentrations of acrolein-lysine adducts, 8-hydroxy-2'-deoxyguanosine (8-OHdG) were determined using competitive enzyme-linked immunosorbent assay, and nitric oxide metabolites were measured using the colorimetric, non-enzymatic assay.

RESULTS

Urinary concentrations of 8-OHdG, but not acrolein-lysine adducts and nitric oxide metabolites, were significantly increased in the diabetic group. For diabetic patients, microalbuminuria was significantly correlated with higher concentrations of all three markers. Hemoglobin A(1c) values were significantly correlated with 8-OHdG values.

CONCLUSIONS

These findings indicate that increased oxidative stress and the risk of vascular complications may be present at early stages of type 1 diabetes.

Matrix metalloproteinase 2 may be a marker of microangiopathy in children and adolescents with type 1 diabetes mellitus

Matrix metalloproteinases (MMPs) 2 and 9 are responsible for extracellular matrix breakdown and their abnormal circulating levels may pre-date clinical evidence of diabetic angiopathy. We detected by ELISA, plasma MMP-2 and MMP-9 levels and associated activity in 25 children and adolescents with T1DM. Thirteen male and 12 female patients were evaluated at the clinical diagnosis and onset of T1DM and again at a 5-year follow-up. Twelve patients had developed microangiopathic complications at the follow-up evaluation. MMP-2 and MMP-9 levels and activity were detected in samples obtained at T1DM diagnosis and at the 5-year follow-up. As controls, 19 healthy subjects who were the same age as the patients were also evaluated at baseline and again after 5 years. MMP-2 levels and activity were significantly higher in the patients than in the controls at disease onset. This was particularly evident when patients who developed microangiopathic complications were compared to controls and patients without complications. At the 5-year follow-up, a significant increase in MMP-2 levels and a significant decrease in MMP-2 activity were found only in the control group compared to the baseline levels. MMP-2 levels and activity were higher in patients with microangiopathy. MMP-9 levels and activity were increased in all groups compared to baseline levels. MMP-9 levels were lower in patients with microangiopathy compared to controls, but no difference was found between the two patient groups. It is well known that MMP-9 is an index of the severity and stability of macroangiopathy while our results allow us to postulate that MMP-2 may be a marker of microangiopathy.

Soluble adhesion molecules (sICAM-1, sVCAM-1) and selectins (sE selectin, sP selectin, sL selectin) levels in children and adolescents with obesity, hypertension, and diabetes

The attachment of monocytes and lymphocytes to endothelial cells, which initiates atherosclerosis, arises under the influence of adhesion molecules. The preclinical phase of this disease lasts many decades, and this provides an opportunity for the presymptomatic detection of high-risk subjects. We evaluated levels of the adhesion molecules: sICAM-1 (soluble intercellular adhesion molecule 1), sVCAM-1 (soluble vascular adhesion molecule 1), sE selectin, sP selectin, and sL selectin in children with atherosclerosis risk factors (n = 123, mean age 15.1 years) (obese [n = 17], hypertensive [n = 25], obese with hypertension [n = 30], type 1 diabetic [n = 51]). Twenty-seven healthy children formed the control group, mean age 15.2 years. sICAM-1 was higher in the study group compared with control (314.1 +/- 61 vs 264.9 +/- 55 ng/mL, P < .01). The same was found for sVCAM-1 (513.7 +/- 187 vs 407.9 +/- 76 ng/mL, P < .05) and E selectin (86.04 +/- 33.6 vs 62.1 +/- 20.3 ng/mL, P < .01). sP-selectin and sL-selectin levels were not different compared with controls. E selectin correlated with body mass index (BMI; r = 0.18, P = .03), total cholesterol (r = 0.2, P = .016), and triglycerides (r = 0.22, P = .008). sICAM-1 correlated with BMI (r = 0.19, P = .019) and systolic blood pressure (r = 0.13, P = .045). In multiple linear regression analysis, sE selectin was found to be associated with triglycerides (R2 = 0.29, P = .045), sICAM-1 dependent on BMI (R2 = 0.58, P = .047), and sVCAM-1 dependent on total cholesterol (R2 = 0.51, P = .006). Elevated concentrations of sICAM-1, sVCAM-1, and E selectin were found in obese, hypertensive, and diabetic children. We conclude that endothelial activation appears in these children, and adhesion molecules are related to the earliest stages of atherosclerosis.

Cardiomyocyte apoptosis induced by short-term diabetes requires mitochondrial GSH depletion

Oxidative stress due to excessive reactive oxygen species (ROS) and depleted antioxidants such as glutathione (GSH) can give rise to apoptotic cell death in acutely diabetic hearts and lead to heart disease. At present, the source of these cardiac ROS or the subcellular site of cardiac GSH loss [i.e., cytosolic (cGSH) or mitochondrial (mGSH) GSH] has not been completely elucidated. With the use of rotenone (an inhibitor of the electron transport chain) to decrease the excessive ROS in acute streptozotocin (STZ)-induced diabetic rat heart, the mitochondrial origin of ROS was established. Furthermore, mitochondrial damage, as evidenced by loss of membrane potential, increases in oxidative stress, and reduction in mGSH was associated with increased apoptosis via increases in caspase-9 and -3 activities in acutely diabetic hearts. To validate the role of mGSH in regulating cardiac apoptosis, l-buthionine-sulfoximine (BSO; 10 mmol/kg ip), which blocks GSH synthesis, or diethyl maleate (DEM; 4 mmol/kg ip), which inactivates preformed GSH, was administered in diabetic rats for 4 days after STZ administration. Although both BSO and DEM lowered cGSH, they were ineffective in reducing mGSH or augmenting cardiomyocyte apoptosis. To circumvent the lack of mGSH depletion, BSO and DEM were coadministered in diabetic rats. In this setting, mGSH was undetectable and cardiac apoptosis was further aggravated compared with the untreated diabetic group. In a separate group, GSH supplementation induced a robust amplification of mGSH in diabetic rat hearts and prevented apoptosis. Our data suggest for the first time that mGSH is crucial for modulating the cell suicide program in short-term diabetic rat hearts.