Oscillating glucose and constant high glucose induce endoglin expression in endothelial cells: the role of oxidative stress

Human Umbilical Vein Endothelial Cells as a Versatile Cellular Model System in Diverse Experimental Paradigms: An Ultrastructural Perspective

Human umbilical vein endothelial cells (HUVECs) are primary cells isolated from the vein of an umbilical cord, extensively used in cardiovascular studies and medical research. These cells, retaining the characteristics of endothelial cells in vivo, serve as a valuable cellular model system for understanding vascular biology, endothelial dysfunction, pathophysiology of diseases such as atherosclerosis, and responses to different drugs or treatments. Transmission electron microscopy (TEM) has been a cornerstone in revealing the detailed architecture of multiple cellular model systems including HUVECs, allowing researchers to visualize subcellular organelles, membrane structures, and cytoskeletal elements. Among them, the endoplasmic reticulum, Golgi apparatus, mitochondria, and nucleus can be meticulously examined to recognize alterations indicative of cellular responses to various stimuli. Importantly, Weibel-Palade bodies are characteristic secretory organelles found in HUVECs, which can be easily distinguished in the TEM. These distinctive structures also dynamically react to different factors through regulated exocytosis, resulting in complete or selective release of their contents. This detailed review summarizes the ultrastructural features of HUVECs and highlights the utility of TEM as a pivotal tool for analyzing HUVECs in diverse research frameworks, contributing valuable insights into the comprehension of HUVEC behavior and enriching our knowledge into the complexity of vascular biology.

Assessment of soluble thrombomodulin and soluble endoglin as endothelial dysfunction biomarkers in seriously ill surgical septic patients: correlation with organ dysfunction and disease severity

BACKGROUND

Sepsis, a complex condition characterized by dysregulated immune response and organ dysfunction, is a leading cause of mortality in ICU patients. Current diagnostic and prognostic approaches primarily rely on non-specific biomarkers and illness severity scores, despite early endothelial activation being a key feature of sepsis. This study aimed to evaluate the levels of soluble thrombomodulin and soluble endoglin in seriously ill surgical septic patients and explore their association with organ dysfunction and disease severity.

METHODOLOGY

A case control study was conducted from March 2022 to November 2022, involving seriously ill septic surgical patients. Baseline clinical and laboratory data were collected within 24 h of admission to the Surgical Intensive Care Unit. This included information such as age, sex, hemodynamic parameters, blood chemistry, SOFA score, qSOFA score, and APACHE-II score. A proforma was filled out to record these details. The outcome of each patient was noted at the time of discharge.

RESULTS

The study found significantly elevated levels of soluble thrombomodulin and soluble endoglin in seriously ill surgical septic patients. The RTqPCR analysis revealed a positive correlation between soluble thrombomodulin and soluble endoglin levels with the qSOFA score, as well as, there was a positive association between RTqPCR soluble thrombomodulin and the SOFA score. These findings indicate a correlation between these biomarkers and organ dysfunction and disease severity.

CONCLUSION

The study concludes that elevated levels of soluble thrombomodulin and soluble endoglin can serve as endothelial biomarkers for early diagnosis and prognostication in seriously ill surgical septic patients.

Alternate day fasting aggravates atherosclerosis through the suppression of hepatic ATF3 in Apoe-/- mice

Atherosclerosis is the major contributor to cardiovascular mortality worldwide. Alternate day fasting (ADF) has gained growing attention due to its metabolic benefits. However, the effects of ADF on atherosclerotic plaque formation remain inconsistent and controversial in atherosclerotic animal models. The present study was designed to investigate the effects of ADF on atherosclerosis in apolipoprotein E-deficient (Apoe -/- ) mice. Eleven-week-old male Apoe -/- mice fed with Western diet (WD) were randomly grouped into ad libitum (AL) group and ADF group, and ADF aggravated both the early and advanced atherosclerotic lesion formation, which might be due to the disturbed cholesterol profiles caused by ADF intervention. ADF significantly altered cholesterol metabolism pathways and down-regulated integrated stress response (ISR) in the liver. The hepatic expression of activating transcription factor 3 (ATF3) was suppressed in mice treated with ADF and hepatocyte-specific overexpression of Aft3 attenuated the effects of ADF on atherosclerotic plaque formation in Apoe -/- mice. Moreover, the expression of ATF3 could be regulated by Krüppel-like factor 6 (KLF6) and both the expressions of ATF3 and KLF6 were regulated by hepatic cellular ISR pathway. In conclusion, ADF aggravates atherosclerosis progression in Apoe -/- mice fed on WD. ADF inhibits the hepatic ISR signaling pathway and decreases the expression of KLF6, subsequently inhibiting ATF3 expression. The suppressed ATF3 expression in the liver mediates the deteriorated effects of ADF on atherosclerosis in Apoe -/- mice. The findings suggest the potentially harmful effects when ADF intervention is applied to the population at high risk of atherosclerosis.

Therapeutic Potential for Beta-3 Adrenoreceptor Agonists in Peripheral Arterial Disease and Diabetic Foot Ulcers

Annually, peripheral arterial disease is estimated to cost over USD 21 billion and diabetic foot disease an estimated at USD 9-13 billion. Mirabegron is a TGA-approved beta-3 adrenoreceptor agonist, shown to be safe and effective in the treatment of overactive bladder syndrome by stimulating bladder smooth muscle relaxation. In this review, we discuss the potential use of beta-3 adrenoreceptor agonists as therapeutic agents repurposed for peripheral arterial disease and diabetic foot ulcers. The development of both conditions is underpinned by the upregulation of oxidative stress pathways and consequential inflammation and hypoxia. In oxidative stress, there is an imbalance of reactive oxygen species and nitric oxide. Endothelial nitric oxide synthase becomes uncoupled in disease states, producing superoxide and worsening oxidative stress. Agonist stimulation of the beta-3 adrenoreceptor recouples and activates endothelial nitric oxide synthase, increasing the production of nitric oxide. This reduces circulating reactive oxygen species, thus decreasing redox modification and dysregulation of cellular proteins, causing downstream smooth muscle relaxation, improved endothelial function and increased angiogenesis. These mechanisms lead to endothelial repair in peripheral arterial disease and an enhanced perfusion in hypoxic tissue, which will likely improve the healing of chronic ulcers.

Synergistic effect of elevated glucose levels with SARS-CoV-2 spike protein induced NOX-dependent ROS production in endothelial cells

BACKGROUND

Diabetic patients infected with coronavirus disease 2019 (COVID-19) often have a higher probability of organ failure and mortality. The potential cellular mechanisms through which blood glucose exacerbates tissue damage due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is still unclear.

METHODS AND RESULTS

We cultured endothelial cells within differing glucose mediums with an increasing concentration gradient of SARS-CoV-2 Spike protein (S protein). S protein can cause the reduction of ACE2 and TMPRSS2, and activation of NOX2 and NOX4. A high glucose medium was shown to aggravate the decrease of ACE2 and activation of NOX2 and NOX4 in cultured cells, but had no effect on TMPRSS2. S protein mediated activation of the ACE2-NOX axis induced oxidative stress and apoptosis within endothelial cells, leading to cellular dysfunction via the reduction of NO and tight junction proteins which may collectively be exacerbated by elevated glucose. In addition, the glucose variability model demonstrated activation of the ACE2-NOX axis in a similar manner observed in the high glucose model in vitro.

CONCLUSIONS

Our present study provides evidence for a mechanism through which hyperglycemia aggravates endothelial cell injury resulting from S protein mediated activation of the ACE2-NOX axis. Our research thus highlights the importance of strict monitoring and control of blood glucose levels within the context of COVID-19 treatment to potentially improve clinical outcomes.

Mutual Regulation between Redox and Hypoxia-Inducible Factors in Cardiovascular and Renal Complications of Diabetes

Oxidative stress and hypoxia-inducible factors (HIFs) have been implicated in the pathogenesis of diabetic cardiovascular and renal diseases. Reactive oxygen species (ROS) mediate physiological and pathophysiological processes, being involved in the modulation of cell signaling, differentiation, and survival, but also in cyto- and genotoxic damage. As master regulators of glycolytic metabolism and oxygen homeostasis, HIFs have been largely studied for their role in cell survival in hypoxic conditions. However, in addition to hypoxia, other stimuli can regulate HIFs stability and transcriptional activity, even in normoxic conditions. Among these, a regulatory role of ROS and their byproducts on HIFs, particularly the HIF-1α isoform, has received growing attention in recent years. On the other hand, HIF-1α and HIF-2α exert mutually antagonistic effects on oxidative damage. In diabetes, redox-mediated HIF-1α deregulation contributes to the onset and progression of cardiovascular and renal complications, and recent findings suggest that deranged HIF signaling induced by hyperglycemia and other cellular stressors associated with metabolic disorders may cause mitochondrial dysfunction, oxidative stress, and inflammation. Understanding the mechanisms of mutual regulation between HIFs and redox factors and the specific contribution of the two main isoforms of HIF-α is fundamental to identify new therapeutic targets for vascular complications of diabetes.

Monoclonal anti-endoglin antibody TRC105 (carotuximab) prevents hypercholesterolemia and hyperglycemia-induced endothelial dysfunction in human aortic endothelial cells

Endoglin (Eng) is a co-receptor of the transforming growth factor β superfamily playing an important role in endothelial dysfunction. TRC105 (carotuximab) is a monoclonal antibody that blocks Eng and its downstream Smad signaling pathway. Here we have investigated for the first time the effects of TRC105 treatment on the development of endothelial dysfunction induced by 7-ketocholesterol (7K) or high glucose (HG), focusing on Eng expression, signaling, and function. In the hypercholesterolemia study, human aortic endothelial cells (HAoECs) were treated with TRC105 (300 μg/ml) for 1 h, followed by the addition of 7K (10 μg/ml) for another 12 h. In the hyperglycemia study, HAoECs were exposed to HG (45 mM) for 60 h, followed by the addition of TRC105 for another 12 h, and cells treated with 5mM glucose and 40 mM mannitol served as control. Protein levels, adhesion, and transmigration of monocytes were assessed by flow cytometry, mRNA expression was measured by qRT-PCR. 7K and HG treatment increased protein levels of NF-κB and Eng and adhesion and transmigration of monocytes through HAoECs monolayer. TRC105 pretreatment reduced the 7K- or HG-induced Eng protein levels and pSmad1/5 and pSmad2/3 signaling. Despite increased protein levels of P-selectin and VCAM-1, TRC105 mediated blockage of Eng prevented 7K- and HG-induced adhesion and transmigration of monocytes through endothelial monolayers. These results suggest that TRC105-mediated Eng blockage can counteract the hypercholesterolemia- and hyperglycemia-induced endothelial dysfunction in HAoECs, suggesting that Eng might be a potential therapeutic target in disorders associated with elevated cholesterol and glucose levels.

The Effect of High and Variable Glucose on the Viability of Endothelial Cells Co-Cultured with Smooth Muscle Cells

Diabetes mellitus causes endothelial dysfunction. The aim of this study was to investigate the effect of normal (5 mmol/L), high (20 mmol/L), and fluctuating (5 and 20 mmol/L changed every day) glucose concentration in the culture medium on the viability of human umbilical vein endothelial cells (HUVECs) co-cultured with human umbilical artery smooth muscle cells (HUASMCs). The cultures were conducted on semi-permeable flat polysulfone (PSU) fibronectin-coated membranes immobilized in self-made inserts. The insert contained either HUVECs on a single membrane or HUASMCs and HUVECs on two membranes close to each other. Cultures were conducted for 7 or 14 days. Apoptosis, mitochondrial potential, and the production of reactive oxygen species and lactate by HUVECs were investigated. The results indicate that fluctuations in glucose concentration have a stronger negative effect on HUVECs viability than constant high glucose concentration. High and fluctuating glucose concentrations slow down cell proliferation compared to the culture carried out in the medium with normal glucose concentration. In conclusion, HUASMCs affect the viability of HUVECs when both types of cells are co-cultured in medium with normal or variable glucose concentration.

Advances in the Role of Endothelial Cells in Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) poses a serious socio-economic burden due to its high prevalence and severe impact on the quality of life of elderly patients. Pathological changes in CSVD mainly influence small cerebral arteries, microarteries, capillaries, and small veins, which are usually caused by multiple vascular risk factors. CSVD is often identified on brain magnetic resonance imaging (MRI) by recent small subcortical infarcts, white matter hyperintensities, lacune, cerebral microbleeds (CMBs), enlarged perivascular spaces (ePVSs), and brain atrophy. Endothelial cell (EC) dysfunction is earlier than clinical symptoms. Immune activation, inflammation, and oxidative stress may be potential mechanisms of EC injury. ECs of the blood–brain–barrier (BBB) are the most important part of the neurovascular unit (NVU) that ensures constant blood flow to the brain. Impaired cerebral vascular autoregulation and disrupted BBB cause cumulative brain damage. This review will focus on the role of EC injury in CSVD. Furthermore, several specific biomarkers will be discussed, which may be useful for us to assess the endothelial dysfunction and explore new therapeutic directions.

Kinetics of Biomarkers of Oxidative Stress in Septic Shock: A Pilot Study

Septic shock is a major cause of mortality in ICU patients, its pathophysiology is complex and not properly understood. Oxidative stress seems to be one of the most important mechanisms of shock progression to multiple organ failure. In the present pilot study, we have analysed eight oxidative-stress-related biomarkers in seven consecutive time points (i.e., the first seven days) in 21 septic shock patients admitted to the ICU. Our objective was to describe the kinetics of four biomarkers related to pro-oxidative processes (nitrite/nitrate, malondialdehyde, 8-oxo-2′-deoxyguanosine, soluble endoglin) compared to four biomarkers of antioxidant processes (the ferric reducing ability of plasma, superoxide dismutase, asymmetric dimethylarginine, mid-regional pro-adrenomedullin) and four inflammatory biomarkers (CRP, IL-6, IL-10 and neopterin). Furthermore, we analysed each biomarker’s ability to predict mortality at the time of admission and 12 h after admission. Although a small number of study subjects were recruited, we have identified four promising molecules for further investigation: soluble endoglin, superoxide dismutase, asymmetric dimethylarginine and neopterin.

Lower miR-21/ROS/HNE levels associate with lower glycemia after habit-intervention: DIAPASON study 1-year later

Background

The prevalence of prediabetes is increasing in the global population and its metabolic derangements may expose to a higher risk to develop type 2 diabetes (T2D) and its cardiovascular burden. Lifestyle modifications might have considerable benefits on ameliorating metabolic status. Alternative biomarkers, such as circulating miR-21, has been recently discovered associated with dysglycemia. Here we evaluated, in a longitudinal cohort of dysglycemic population the relation between the circulating miR-21/ROS/HNE levels and the habit-intervention (HI) after 1 year of follow-up.

Methods

1506 subjects from DIAPASON study were screened based on the Findrisc score. Of them, 531 subjects with Findrisc ≥ 9 were selected for dysglycemia (ADA criteria) and tested for circulating miR-21, ROS and HNE levels, as damaging-axis. 207 subjects with dysglycemia were re-evaluated after 1-year of habit intervention (HI). Repeated measures tests were used to evaluate changes from baseline to 1-year of follow-up. The associations between glycemic parameters and miR-21/ROS/HNE were implemented by linear regression and logistic regression models.

Results

After HI, we observed a significant reduction of miR-21/ROS/HNE axis in dysglycemic subjects, concomitantly with ameliorating of metabolic parameters, including insulin resistance, BMI, microalbuminuria, reactive hyperemia index and skin fluorescence. Significant positive interaction was observed between miR-21 axis with glycaemic parameters after HI. Lower miR-21 levels after HI, strongly associated with a reduction of glycemic damaging-axis, in particular, within-subjects with values of 2hPG < 200 mg/dL.

Conclusions

Our findings demonstrated that HI influenced the epigenetic changes related to miR-21 axis, and sustain the concept of reversibility from dysglycemia. These data support the usefulness of novel biological approaches for monitoring glycemia as well as provide a screening tool for preventive programmes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01465-0.

Glycemic Variability Is Independently Associated With Poor Prognosis in Five Pediatric ICU Centers in Southwest China

Background

Glucose variability (GV) is a common complication of dysglycemia in critically ill patients. However, there are few studies on the role of GV in the prognosis of pediatric patients, and there is no consensus on the appropriate method for GV measurement. The objective of this study was to determine the “optimal” index of GV in non-diabetic critically ill children in a prospective multicenter cohort observational study. Also, we aimed to confirm the potential association between GV and unfavorable outcomes and whether this association persists after controlling for hypoglycemia or hyperglycemia.

Materials and Methods

Blood glucose values were recorded for the first 72 h and were used to calculate the GV for each participant. Four different metrics [SD, glycemic lability index (GLI), mean absolute glucose (MAG), and absolute change of percentage (ACACP)] were considered and compared to identify the “best” GV index associated with poor prognosis in non-diabetic critically ill children. Among the four metrics, the SD was most commonly used in previous studies, while GLI- and MAG-integrated temporal information, that is the rate and magnitude of change and the time interval between glucose measurements. The fourth metric, the average consecutive ACACP, was introduced in our study, which can be used in real-time clinical decisions. The primary outcome of this study was the 28-day mortality. The receiver operating characteristic (ROC) curve analysis was conducted to compare the predictive power of different metrics of GV for the primary outcome. The GV index with the largest area under ROC curve (AUC) was chosen for subsequent multivariate analyses. Multivariate Cox regression analysis was performed to identify the potential predictors of the outcome. To compare the contribution in 28-day mortality prognosis between glycemic variability and hyper- or hypoglycemia, performance metrics were calculated, which included AUC, net reclassification improvement (NRI), and integrated discrimination improvement (IDI).

Results

Among 780 participants, 12.4% (n = 97) died within 28 days after admission to the pediatric intensive care unit (PICU). Statistically significant differences were found between survivors and non-survivors in terms of four GV metrics (SD, GLI, MAG, and ACACP), in which MAG (AUC: 0.762, 95% CI: 0.705–0.819, p < 0.001) achieved the largest AUC and showed a strong independent association with ICU mortality. Subsequent addition of MAG to the multivariate Cox model for hyperglycemia resulted in further quantitative evolution of the model statistics (AUC = 0.651–0.681, p = 0.001; IDI: 0.017, p = 0.044; NRI: 0.224, p = 0.186). The impact of hyperglycemia (adjusted hazard ratio [aHR]: 1.419, 95% CI: 0.815–2.471, p = 0.216) on outcome was attenuated and no longer statistically relevant after adjustment for MAG (aHR: 2.455, 95% CI: 1.411–4.270, p = 0.001).

Conclusions

GV is strongly associated with poor prognosis independent of mean glucose level, demonstrating more predictive power compared with hypoglycemia and hyperglycemia after adjusting for confounding factors. GV metrics that contain information, such as time and rate of change, are the focus of future research; thus, the MAG may be a good choice. The findings of this study emphasize the crucial role of GVs in children in the PICU. Clinicians should pay more attention to GV for clinical glucose management.

Metformin in cardiovascular diabetology: a focused review of its impact on endothelial function

As a first-line treatment for diabetes, the insulin-sensitizing biguanide, metformin, regulates glucose levels and positively affects cardiovascular function in patients with diabetes and cardiovascular complications. Endothelial dysfunction (ED) represents the primary pathological change of multiple vascular diseases, because it causes decreased arterial plasticity, increased vascular resistance, reduced tissue perfusion and atherosclerosis. Caused by “biochemical injury”, ED is also an independent predictor of cardiovascular events. Accumulating evidence shows that metformin improves ED through liver kinase B1 (LKB1)/5'-adenosine monophosphat-activated protein kinase (AMPK) and AMPK-independent targets, including nuclear factor-kappa B (NF-κB), phosphatidylinositol 3 kinase-protein kinase B (PI3K-Akt), endothelial nitric oxide synthase (eNOS), sirtuin 1 (SIRT1), forkhead box O1 (FOXO1), krüppel-like factor 4 (KLF4) and krüppel-like factor 2 (KLF2). Evaluating the effects of metformin on endothelial cell functions would facilitate our understanding of the therapeutic potential of metformin in cardiovascular diabetology (including diabetes and its cardiovascular complications). This article reviews the physiological and pathological functions of endothelial cells and the intact endothelium, reviews the latest research of metformin in the treatment of diabetes and related cardiovascular complications, and focuses on the mechanism of action of metformin in regulating endothelial cell functions.

Myogenetic Oligodeoxynucleotide (myoDN) Recovers the Differentiation of Skeletal Muscle Myoblasts Deteriorated by Diabetes Mellitus

Skeletal muscle wasting in patients with diabetes mellitus (DM) is a complication of decreased muscle mass and strength, and is a serious risk factor that may result in mortality. Deteriorated differentiation of muscle precursor cells, called myoblasts, in DM patients is considered to be one of the causes of muscle wasting. We recently developed myogenetic oligodeoxynucleotides (myoDNs), which are 18-base single-strand DNAs that promote myoblast differentiation by targeting nucleolin. Herein, we report the applicability of a myoDN, iSN04, to myoblasts isolated from patients with type 1 and type 2 DM. Myogenesis of DM myoblasts was exacerbated concordantly with a delayed shift of myogenic transcription and induction of interleukins. Analogous phenotypes were reproduced in healthy myoblasts cultured with excessive glucose or palmitic acid, mimicking hyperglycemia or hyperlipidemia. iSN04 treatment recovered the deteriorated differentiation of plural DM myoblasts by downregulating myostatin and interleukin-8 (IL-8). iSN04 also ameliorated the impaired myogenic differentiation induced by glucose or palmitic acid. These results demonstrate that myoDNs can directly facilitate myoblast differentiation in DM patients, making them novel candidates for nucleic acid drugs to treat muscle wasting in patients with DM.

Quercetin Antagonizes Glucose Fluctuation Induced Renal Injury by Inhibiting Aerobic Glycolysis via HIF-1α/miR-210/ISCU/FeS Pathway

Background and Objective: Glucose fluctuation (GF) has been reported to induce renal injury and diabetic nephropathy (DN). However, the mechanism still remains ambiguous. Mitochondrial energy metabolism, especially aerobic glycolysis, has been a hotspot of DN research for decades. The activation of HIF-1α/miR210/ISCU/FeS axis has provided a new explanation for aerobic glycolysis. Our previous studies indicated quercetin as a potential therapeutic drug for DN. This study aims to evaluate levels of aerobic glycolysis and repressive effect of quercetin via HIF-1α/miR210/ISCU/FeS axis in a cell model of GF. Methods: The mouse glomerular mesangial cells (MCs) were exposed in high or oscillating glucose with or without quercetin treatment. Cell viability was measured by CCK8 assay. Aerobic glycolysis flux was evaluated by lactate acid, pH activity of PFK. Apoptosis level was confirmed by Annexin V-APC/7-AAD double staining and activity of caspase-3. TNF-α and IL-1β were used to evaluate inflammation levels. Results: GF deteriorated inflammation damage and apoptosis injury in MCs, while quercetin could alleviate this GF-triggered cytotoxicity. GF intensified aerobic glycolysis in MCs and quercetin could inhibit this intensification in a dose-dependent manner. Quercetin prevented activities of two FeS-dependent metabolic enzymes, aconitase, and complex I, under GF injury in MCs. The mRNA expression and protein contents of HIF-1α were increased after GF exposure, and these could be alleviated by quercetin treatment. Knockdown of ISCU by siRNA and Up-regulating of miR-210 by mimic could weaken the effects of quercetin that maintained protein levels of ISCU1/2, improved cell viability, relieved inflammation injury, decreased apoptosis, and reduced aerobic glycolysis switch in MCs. Conclusion: Quercetin antagonizes GF-induced renal injury by suppressing aerobic glycolysis via HIF-1α/miR-210/ISCU/FeS pathway in MCs cell model. Our findings contribute to a new insight into understanding the mechanism of GF-induced renal injury and protective effects of quercetin.

Membrane and soluble endoglin role in cardiovascular and metabolic disorders related to metabolic syndrome

Membrane endoglin (Eng, CD105) is a transmembrane glycoprotein essential for the proper function of vascular endothelium. It might be cleaved by matrix metalloproteinases to form soluble endoglin (sEng), which is released into the circulation. Metabolic syndrome comprises conditions/symptoms that usually coincide (endothelial dysfunction, arterial hypertension, hyperglycemia, obesity-related insulin resistance, and hypercholesterolemia), and are considered risk factors for cardiometabolic disorders such as atherosclerosis, type II diabetes mellitus, and liver disorders. The purpose of this review is to highlight current knowledge about the role of Eng and sEng in the disorders mentioned above, in vivo and in vitro extent, where we can find a wide range of contradictory results. We propose that reduced Eng expression is a hallmark of endothelial dysfunction development in chronic pathologies related to metabolic syndrome. Eng expression is also essential for leukocyte transmigration and acute inflammation, suggesting that Eng is crucial for the regulation of endothelial function during the acute phase of vascular defense reaction to harmful conditions. sEng was shown to be a circulating biomarker of preeclampsia, and we propose that it might be a biomarker of metabolic syndrome-related symptoms and pathologies, including hypercholesterolemia, hyperglycemia, arterial hypertension, and diabetes mellitus as well, despite the fact that some contradictory findings have been reported. Besides, sEng can participate in the development of endothelial dysfunction and promote the development of arterial hypertension, suggesting that high levels of sEng promote metabolic syndrome symptoms and complications. Therefore, we suggest that the treatment of metabolic syndrome should take into account the importance of Eng in the endothelial function and levels of sEng as a biomarker and risk factor of related pathologies.

Protective Effect and Mechanism of Bone Morphogenetic Protein-4 on Apoptosis of Human Lens Epithelium Cells under Oxidative Stress

Bone morphogenetic proteins (BMPs), a member of the transforming growth factor β (TGF-β) superfamily, are abundant in human ocular tissues and play an important role in lens development. Targeted deletion of BMP-4 in mice results in failure of lens placode formation. Following lens maturation, the formation of senile cataracts is demonstrably associated with free radical-related oxidative stress. Previous studies reported that BMPs play an antiapoptotic role in cells under oxidative stress, and the BMP-4 signal is important in inflammation regulation and homeostasis. BMP-4 evidently suppressed the apoptosis of human lens epithelial cells (HLECS) under oxidative stress induced by H₂O₂. This protective antiapoptotic effect is partly due to a decrease in caspase-3 activity and reactive oxygen species (ROS) level. Furthermore, the expression of activating transcription factor- (ATF-) 6 and Krüppel-like factor- (KLF-) 6 increased under oxidative stress and decreased after BMP-4 treatment.

Effects of modified lipoproteins on human trophoblast cells: a role in pre-eclampsia in pregnancies complicated by diabetes

INTRODUCTION

Pre-eclampsia (PE) is increased ~4-fold by maternal diabetes. Elevated plasma antiangiogenic factors, soluble fms-like tyrosine kinase (sFLT-1) and soluble endoglin (sENG), precede PE onset. We investigated whether diabetes-related stresses, modified lipoproteins and elevated glucose enhance trophoblast sFLT-1 and sENG release and/or alter placental barrier function and whether oxidized low-density lipoprotein (Ox-LDL) is in placental tissue.

RESEARCH DESIGN AND METHODS

HTR8/SVneo cells were exposed to 'heavily-oxidized, glycated' LDL (HOG-LDL) versus native LDL (N-LDL) (10-200 mg protein/L) for 24 hours ±pretreatment with glucose (30 mmol/L, 72 hours). Concentrations of sFLT-1 and sENG in supernatants (by ELISA) and expressions of sFLT-1-I13 and sFLT-1-E15A isoforms, endoglin (ENG) and matrix metalloproteinase-14 (MMP-14; by RT-PCR) were quantified. For barrier studies, JAR cells were cultured in Transwell plates (12-14 days), then exposed to LDL. Transepithelial electrical resistance (TEER) was measured after 6, 12 and 24 hours. In placental sections from women with and without type 1 diabetes, immunostaining of apolipoprotein B100 (ApoB, a marker of LDL), Ox-LDL and lipoxidation product 4-hydroxynonenal was performed.

RESULTS

HOG-LDL (50 mg/L) increased sFLT-1 (2.7-fold, p<0.01) and sENG (6.4-fold, p<0.001) in supernatants versus N-LDL. HOG-LDL increased expression of sFLT-1-I13 (twofold, p<0.05), sFLT-1-E15A (1.9-fold, p<0.05), ENG (1.6-fold, p<0.01) and MMP-14 (1.8-fold, p<0.05) versus N-LDL. High glucose did not by itself alter sFLT-1 or sENG concentrations, but potentiated effects of HOG-LDL on sFLT-1 by 1.5-fold (p<0.05) and on sENG by 1.8-fold (p<0.01). HOG-LDL (200 mg/L) induced trophoblast barrier impairment, decreasing TEER at 6 hours (p<0.01), 12 hours (p<0.01) and 24 hours (p<0.05) versus N-LDL. Immunostaining of term placental samples from women both with and without diabetes revealed presence of intravillous modified lipoproteins.

CONCLUSION

These findings may explain, in part, the high risk for PE in women with diabetes. The trophoblast culture model has potential for evaluating novel therapies targeting barrier dysfunction.

Does microRNA Perturbation Control the Mechanisms Linking Obesity and Diabetes? Implications for Cardiovascular Risk

Metabolic disorders such as obesity and type 2 diabetes (T2D) are considered the major risk factors for the development of cardiovascular diseases (CVD). Although the pathological mechanisms underlying the mutual development of obesity and T2D are difficult to define, a better understanding of the molecular aspects is of utmost importance to identify novel therapeutic targets. Recently, a class of non-coding RNAs, called microRNAs (miRNAs), are emerging as key modulators of metabolic abnormalities. There is increasing evidence supporting the role of intra- and extracellular miRNAs as determinants of the crosstalk between adipose tissues, liver, skeletal muscle and other organs, triggering the paracrine communication among different tissues. miRNAs may be considered as risk factors for CVD due to their correlation with cardiovascular events, and in particular, may be related to the most prominent risk factors. In this review, we describe the associations observed between miRNAs expression levels and the most common cardiovascular risk factors. Furthermore, we sought to depict the molecular aspect of the interplay between obesity and diabetes, investigating the role of microRNAs in the interorgan crosstalk. Finally, we discussed the fascinating hypothesis of the loss of protective factors, such as antioxidant defense systems regulated by such miRNAs.

Prevention of Diabetes and Cardiovascular Disease in Obesity

Obesity is one of the major risk factors for the development of both impaired glucose tolerance (IGT, or prediabetes) and type 2 diabetes (T2D), and its prevalence worldwide drives toward an increased rate of cardiovascular morbidity and mortality. Given the estimations of the World Health Organization (WHO) and the recommendation of the Diabetes Prevention Program (DPP), where IGT and diabetes are considered as risk factors for the development of cardiovascular complications and obesity, the development of diabetes should be treated because of its potential reversibility. In this view, several interventions such as diet, lifestyle changes, and pharmacological treatment are effective, including bariatric metabolic surgery (BMS), which is the most incisive way to efficiently lower body weight. In this review, we sought to summarize some of the major aspects linked to diabetes prevention in overweight/obesity, focusing on the use of surgery; we also attempted to elucidate molecular pathways involved in a variety of obesity-induced processes able to favor the progression of chronic diseases, such as diabetes and its complications.

Novel Biomarkers for Evaluation of Endothelial Dysfunction

Endothelial dysfunction is one of the earliest indicators of cardiovascular (CV) dysfunction, and its evaluation would be of considerable importance to stratify CV risk of many diseases and to assess the efficacy of atheroprotective treatments. Flow-mediated dilation is the most widely used method to study endothelial function. However, it is operator-dependent and can be influenced by physiological variations. Circulating biomarkers are a promising alternative. Due to the complexity of endothelial function, many of the biomarkers studied do not provide consistent information about the endothelium when measured alone. New circulating markers are being explored and some of them are thought to be suitable for the clinical setting. In this review, we focus on novel biomarkers of endothelial dysfunction, particularly endothelial microparticles, endocan, and endoglin, and discuss whether they fulfill the criteria to be applied in clinical practice.

Glucose-induced oxidative stress and accelerated aging in endothelial cells are mediated by the depletion of mitochondrial SIRTs

Diabetic complications cause significant morbidity and mortality. Dysfunction of vascular endothelial cells (ECs), caused by oxidative stress, is a main mechanism of cellular damage. Oxidative stress accelerates EC senescence and DNA damage. In this study, we examined the role of mitochondrial sirtuins (SIRTs) in glucose-induced oxidative stress, EC senescence, and their regulation by miRNAs. Human retinal microvascular endothelial cells (HRECs) were exposed to 5 mmol/L (normoglycemia; NG) or 25 mmol/L glucose (hyperglycemia; HG) with or without transfection of miRNA antagomirs (miRNA-1, miRNA-19b, and miRNA-320; specific SIRT-targeting miRNAs). Expressions of SIRT3, 4 and 5 and their targeting miRNAs were examined using qRT-PCR and ELISAs were used to study SIRT proteins. Cellular senescence was investigated using senescence-associated β-gal stain; while, oxidative stress and mitochondrial alterations were examined using 8-OHdG staining and cytochrome B expressions, respectively. A streptozotocin-induced diabetic mouse model was also used and animal retinas and hearts were collected at 2 months of diabetes. In HRECs, HG downregulated the mRNAs of SIRTs, while SIRT-targeting miRNAs were upregulated. ELISA analyses confirmed such downregulation of SIRTs at the protein level. HG additionally caused early senescence, endothelial-to-mesenchymal transition and oxidative DNA damage in ECs. These changes were prevented by the transfection of specific miRNA antagomirs and by resveratrol. Retinal and cardiac tissues from diabetic mice also showed similar reductions of mitochondrial SIRTs. Collectively, these findings demonstrate a novel mechanism in which mitochondrial SIRTs regulate glucose-induced cellular aging through oxidative stress and how these SIRTs are regulated by specific miRNAs. Identifying such mechanisms may lead to the discovery of novel treatments for diabetic complications.

Plasma endoglin in Type2 diabetic patients with nephropathy

BACKGROUND

Diabetic nephropathy may be a common complication of diabetes mellitus. Endoglin is glycoprotein located on cell surfaces of endothelial cells and is part of the transforming growth factor beta (TGF- β) receptor. Endoglin expression is enhanced in endothelial cells during injury and inflammation. The aim of this study was to estimate the plasma level of soluble endoglin (sEng) in type 2 diabetic patients (with and without nephropathy). Also to explore its availability as marker for disease progression.

METHODS

In this study, sixty eight patients with type 2 diabetes mellitus (T2DM) were included; the patients were sub-grouped to normoalbuminuria without nephropathy and moderately increased albuminuria (microalbuminuria) with nephropathy groups with 13 individuals as control group. Plasma soluble endoglin level was determined using ELISA technique. Fasting plasma glucose (FPG), glycated haemoglobin (HbA1c), lipid profile, and creatinine were determined using colorimetric assay, whereas glomerular filtration rate (GFR) was calculated.

RESULTS

The plasma level of sEng of both normoalbuminuria group 1 and microalbuminuria group 2 were significantly higher when compared to control group. While, the plasma level of sEng in microalbuminuria group 2 was nonsignificant lower when compared to normoalbuminuria group 1. Also, there was a significant positive association between plasma level of sEng and HbA1c, HDL-C and urinary albumin concentration in normoalbuminuria group.

CONCLUSION

Plasma level of soluble Endoglin is markedly increase prior to alteration in endothelial function, and increases to lesser extent with the developing of diabetic nephropathy which indicated disease progression and development of vascular abnormalities.

Novel insights into the regulation of miRNA transcriptional control: implications for T2D and related complications

In recent years, epigenetics has emerged as an important form of biological regulation involving chromatin control of gene expression. The mechanisms of this fine-tuned regulation are susceptible to changes forced by environmental stimuli and nutritional factors and may be potentially reversible. Dysregulation of epigenetic processes has important consequences for the pathogenesis of complex and multifactorial diseases such as type 2 diabetes (T2D) and vascular complications. Along with DNA methylation (DNA-me), histone modifications and RNA-based mechanisms as the major epigenetic controllers, small non-coding RNAs known as microRNAs (miRNAs) have their own important implications for the pathogenesis of diabetes. There is increasing evidence supporting the role of miRNAs in modulating gene expression, cumulatively contributing to epigenetic gene silencing by acting either on the methylation status of the cells or in alternative roles. Although significant progress has been made in the characterization of miRNA functions, most miRNA promoters have not yet been characterized, and the transcriptional regulation of miRNAs remains elusive. The present work is centred on the new biological insights pertaining to the epigenetics-miRNA regulatory axis, focusing on the development of T2D and cardiovascular complications, and the ability of these mechanisms to interact in a network of DNA-me regulation. The genomic organization of inter- and intragenic miRNA genes is discussed, and the mutual connections between pre-mRNA splicing and miRNA biogenesis are summarized, along with the discovery of novel miRNA transcriptional regulation sites.

Glucose-sensing microRNA-21 disrupts ROS homeostasis and impairs antioxidant responses in cellular glucose variability

Background

Antioxidant enzymes play a fundamental role in counteracting oxidative stress induced by high glucose. Although mitochondrial superoxide dismutase (SOD2) is the principal defence against the toxicity of superoxide anions, the mechanism of its inactivation in diabetic subjects is still poorly understood. Recently, microRNA-21 has been associated with diabetes, although its function remains unclear. We sought to explore the mechanism underlying defective SOD2 antioxidant response in HUVECs during exposures to constant high glucose and oscillating glucose (as glucose variability model, GV) and the role of miR-21 in increasing the susceptibility to oxidative stress by disrupting reactive oxygen species (ROS) homeostasis.

Methods

HUVECs exposed for 1 week to constant high glucose and GV were subjected to quantitative electron paramagnetic resonance for ROS measurements. Superoxide anions, SOD2 protein levels and mitochondrial membrane potential (ΔΨm) were also evaluated. Endogenous miR-21 and its putative ROS-homeostatic target genes (KRIT1, FoxO1, NFE2L2 and SOD2) were tested using mimic-miR-21 and quantified by qPCR. Luciferase assays were performed to test miR-21/3′-UTR-SOD2 binding.

Results

We observed upregulation of microRNA-21, overproduction of superoxide anions and total ROS generation, depolarisation of the mitochondrial membrane potential (ΔΨm) and defective SOD2 antioxidant response in HUVECs subjected to constant high glucose and GV exposures. We also found that exogenous mimic-microRNA-21 targeted putative microRNA-21 ROS-homeostatic target genes, e.g., KRIT1, NRF2 and SOD2, which were significantly downregulated. All these effects were reverted by a microRNA-21 inhibitor, which improved SOD2 and KRIT1 expression, reduced the levels of ROS production and ameliorated ΔΨm.

Conclusions

Our data demonstrate the association of microRNA-21 with oscillating and high glucose and early mitochondrial dysfunction. We found that microRNA-21 may promote the suppression of homeostatic signalling that normally limits ROS damage. These data provide novel clues about the inhibition of microRNA-21 as a new therapeutic approach to protect against cellular oxidative injury in glucose variability and diabetes.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0748-2) contains supplementary material, which is available to authorized users.

Gestational glucocorticoid exposure disrupts glucose homeostasis that is accompanied by increased endoglin and DPP-4 activity instead of GSK-3 in rats

Gestational glucocorticoid (GC) treatment has been associated with cardiometabolic disorder (CMD) in offspring's in later life. Elevated dipeptidyl peptidase-4 (DPP-4) activity, endoglin and glycogen synthase kinase-3 (GSK-3) has also been implicated in the development of insulin resistance (IR) and/or vascular inflammation. We aimed to investigate the impact of GC exposure on glucose metabolism and the circulating levels of inflammatory biomarkers, DPP-4 activity and GSK-3 in pregnant rats. Pregnant Wistar rats received either vehicle or dexamethasone (DEX; 0.2 mg/kg; po) between gestational days 14 and 19. Gestational GC exposure resulted in impaired glucose homeostasis that is accompanied with elevated circulating levels of inflammatory biomarkers (endoglin, uric acid, and platelet/lymphocyte ratio), oxidative stress (malondialdehyde), blood viscosity, reduced NO level and increased DPP-4 activity. However, these effects were associated with atherogenic dyslipidemia and reduced GSK-3.We conclude that plasma endoglin, a marker of vascular inflammation, and plasma DPP-4 activity are increased in pregnant rats treated with GC during late gestation. Therefore, glucose deregulation associated with gestational GC exposure is through endoglin-/DPP-4-dependent but GSK-3-independent pathway.

Interpretation of metabolic memory phenomenon using a physiological systems model: What drives oxidative stress following glucose normalization?

Hyperglycemia is generally associated with oxidative stress, which plays a key role in diabetes-related complications. A complex, quantitative relationship has been established between glucose levels and oxidative stress, both in vitro and in vivo. For example, oxidative stress is known to persist after glucose normalization, a phenomenon described as metabolic memory. Also, uncontrolled glucose levels appear to be more detrimental to patients with diabetes (non-constant glucose levels) vs. patients with high, constant glucose levels. The objective of the current study was to delineate the mechanisms underlying such behaviors, using a mechanistic physiological systems modeling approach that captures and integrates essential underlying pathophysiological processes. The proposed model was based on a system of ordinary differential equations. It describes the interplay between reactive oxygen species production potential (ROS), ROS-induced cell alterations, and subsequent adaptation mechanisms. Model parameters were calibrated using different sources of experimental information, including ROS production in cell cultures exposed to various concentration profiles of constant and oscillating glucose levels. The model adequately reproduced the ROS excess generation after glucose normalization. Such behavior appeared to be driven by positive feedback regulations between ROS and ROS-induced cell alterations. The further oxidative stress-related detrimental effect as induced by unstable glucose levels can be explained by inability of cells to adapt to dynamic environment. Cell adaptation to instable high glucose declines during glucose normalization phases, and further glucose increase promotes similar or higher oxidative stress. In contrast, gradual ROS production potential decrease, driven by adaptation, is observed in cells exposed to constant high glucose.

The influence of lipoic acid on caveolin-1-regulated antioxidative enzymes in the mouse model of acute ulcerative colitis

AIM

This study was undertaken to verify if two-weeks treatment of lipoic acid (LA) influence colon damage and pro-inflammatory cytokine synthesis during DSS-induced acute colitis. Moreover, as LA has anti-oxidative properties, we analyzed its influence on the level of antioxidative enzymes, HO-1 and eNOS, and their regulator- caveolin-1.

METHODS

LA was administrated to male C57/BALBc mice at a dose of 25 or 50mg/kg/day (i.p.) for 21days. Acute colitis was induced by administration of 4% DSS (w/v) in drinking water for 5days, followed by 2days of normal drinking water. Mice in LA+DSS groups were treated with LA (25 or 50mg/kg/day; i.p.) starting 14days prior to 4% DSS. Control group received saline for 21days. In the colon tissue we measured myeloperoxidase activity (MPO), IL-1β, IL-6, IL-17A, IL-23 (ELISA method), and tissue level of cav-1, phospho-eNOS, total eNOS and HO-1 (Western blot).

RESULTS

Administration of DSS significantly increased total colon damage (p<0.001), myeloperoxidase (MPO) activity (p<0.05) and pro-inflammatory IL-6 (p<0.05). There was also a tendency towards higher IL-1β, IL-17A, and IL-23 in the colon. LA alone did not influence total colon damage, MPO activity, and pro-inflammatory cytokines concentration compared to control (p<0.05). Notably, mice treated with LA and DSS had significantly decreased total colon damage score (p<0.001), despite augmented colon MPO activity (p<0.01), but similar (IL-17A) or even significantly higher level (IL-1β, IL-23) as compared to the DSS group (p<0.05). IL-6 was insignificantly decreased after LA treatment at a dose of 50mg/kg. In acute colitis there was a tendency towards an increase in cav-1 and HO-1 and a decrease p-eNOS/total eNOS ratio. Moreover, the LA+DSS groups had higher expression of HO-1 and p-eNOS/total eNOS (p<0.05) compared to the DSS group, and a tendency towards higher cav-1 level. The changes did not depend on LA dose.

CONCLUSION

Our study indicated that LA, at lower doses, may influence cav-1-regulated antioxidative enzyme levels (HO-1 and p-eNOS/total eNOS) despite an increase in colon pro-inflammatory cytokine levels during acute colitis. Hence, LA treatment may be - to some extent - beneficial in attenuation of acute colitis.

Soluble Endoglin Level Increase Occurs Prior to Development of Subclinical Structural Vascular Alterations in Diabetic Adolescents

OBJECTIVE

Soluble endoglin (S-endoglin) has been implicated as a potential marker of endothelial dysfunction (ED) and was reported to be elevated in diabetic adults, correlating with the severity of diabetic vasculopathy. However, circulating S-endoglin and its association with other markers of ED have not been formerly analyzed in the first decade of diabetes onset in adolescents with type 1 diabetes mellitus (T1DM).

METHODS

Fifty-eight adolescents with moderately/poorly controlled T1DM were included in this study and twenty-nine healthy adolescents served as controls. The diabetic group was divided into two groups based on the presence of microalbuminuria, as the microalbuminuria group (n=15) and the normoalbuminuria group (n=43). Functional vascular alterations were evaluated by measuring serum S-endoglin and plasma nitric oxide (NO) concentrations, the flow-mediated dilatation (FMD) of the brachial artery. Carotid intima media thickness (CIMT) was measured for evaluation of structural vascular alterations.

RESULTS

The S-endoglin and NO levels of both microalbuminuria and normoalbuminuria groups were higher than those of the control group (for S-endoglin, p=0.047 and p<0.001; for NO, p=0.004 and p=0.006, respectively). The FMD percent was lower in the microalbuminuria group compared to the normoalbuminuria and control groups (p=0.036 and p=0.020, respectively). There were negative correlations between S-endoglin concentration and FMD percent (r=-0.213, p=0.051) and between serum S-endoglin concentration and albumin excretion rate (r=-0.361, p=0.005). No significant differences were found in CIMT among any of the groups (p=0.443).

CONCLUSION

In adolescents with T1DM, S-endoglin concentrations might increase in parallel to the deterioration in endothelial function before subclinical structural vascular alterations become evident.

Oscillating glucose induces microRNA-185 and impairs an efficient antioxidant response in human endothelial cells

BACKGROUND

Intracellular antioxidant response to high glucose is mediated by Cu/Mn-superoxide dismutases (SOD-1/SOD-2), catalase (CAT) and glutathione peroxidases (GPx), particularly glutathione peroxidase-1 (GPx-1). Although oscillating glucose can induce a more deleterious effect than high glucose on endothelial cells, the mechanism by which oscillating glucose exerts its dangerous effects is incompletely understood; however, the involvement of oxidative damage has been generally accepted. In this study we sought to determine whether oscillating glucose differentially modulates antioxidant response, and to elucidate the potential regulatory mechanisms exerted by the microRNA-185 (miR-185).

METHODS

Human endothelial cells were exposed for 1 week to constant and oscillating high glucose. SOD-1, SOD-2, CAT and GPx-1, as well as two markers of oxidative stress [8-hydroxy-2'-deoxyguanosine (8-OHdG) and the phosphorylated form of H2AX (γ-H2AX)] were measured at the end of the experiment. Intracellular miR-185 was measured and loss-of function assays were performed in HUVEC. Bioinformatic tool was used to predict the link between miR-185 on 3'UTR of GPx-1 gene. Luciferase assay was performed to confirm the binding on HUVEC.

RESULTS

After exposure to constant high glucose SOD-1 and GPx-1 increased, while in oscillating glucose SOD-1 increased and GPx-1 did not. SOD-2 and CAT remained unchanged under both conditions. A critical involvement of oscillating glucose-induced miR-185 in the dysregulation of endogenous GPx-1 was found. Computational analyses predict GPx-1 as miR-185's target. HUVEC cultures were used to confirm glucose's causal role on the expression of miR-185, its target mRNA and protein and finally the activation of antioxidant response. In vitro luciferase assays confirmed computational predictions targeting of miR-185 on 3'-UTR of GPx-1 mRNA. Knockdown of miR-185, using anti-miR-185 inhibitor, was accompanied by a significant upregulation of GPx-1 in oscillating glucose. 8-OHdG and γ-H2AX increased more in oscillating glucose than in constant high glucose.

CONCLUSIONS

Glucose oscillations may exert more deleterious effects on the endothelium than high glucose, likely due to an impaired response of GPx-1, coupled by the upregulation of miR-185.

Effect of glucose variability on pathways associated with glucotoxicity in diabetes: Evaluation of a novel in vitro experimental approach

AIMS

Glycaemic variability (GV) has been hypothesized to increase the risk of diabetes complications; however, results of clinical studies are contradictory. The effect of GV on cell phenotypes has been investigated in vitro showing that GV may have more deleterious effect on cells that high glucose itself. However, methodology used to study GV in vitro differs significantly between studies and does not reflect in vivo situation. Therefore we aimed to establish clinically relevant an in vitro experimental approach for the study of GV that reflects intra-day glucose fluctuations of subjects with type 1 diabetes mellitus (T1DM) and of healthy subjects and to test how low and high GV affect expression of genes that protects cells from hyperglycaemia-induced damage.

METHODS

Human umbilical vein endothelial cells (HUVEC) were cultured 24h in medium with different glucose profiles: high GV, low GV and GV of healthy subjects-profiles created according to CGM of T1DM patients and healthy subjects. These profiles were compared to commonly used 5.5 and 25mmol/l glucose concentrations. Gene expression was determined using quantitative PCR.

RESULTS

Our results showed general down-regulation of enzymes that are involved in the protection against hyperglycaemia-induced intracellular changes in both low and high GV compared to normal glycaemia similarly to the decrease induced by continuous hyperglycaemia. Gene expressions did not differ between high and low GV.

CONCLUSION

Our data indicate that GV may have similar or even greater effect than continuous hyperglycaemia on the expression of several genes relevant to pathogenesis of diabetes microvascular complications.

Atherogenicity of postprandial hyperglycemia and lipotoxicity

Type 2 diabetes is characterized by a gradual decline in insulin secretion in response to nutrient loads; hence, it is primarily a disorder of postprandial glucose regulation. However, physicians continue to rely on fasting plasma glucose and glycated hemoglobin to guide management. There is a linear relationship between the risk of cardiovascular death and the 2-h oral glucose tolerance test, while a study confirms postprandial hyperglycemia as independent risk factor for cardiovascular disease in type 2 diabetes. At the same time, several studies show that postprandial hypertriglyceridemia may also be a cardiovascular risk factor. Interestingly, the simultaneous presence of postprandial hyperglycemia and postprandial hypertriglyceridemia has an additive effect in worsening endothelial function and inflammation. Evidence supports the hypothesis glucose postprandial hyperglycemia and hypertriglyceridemia may favor the appearance of the cardiovascular disease through the generation of an oxidative stress. Furthermore, clinical data suggest that postprandial hyperglycemia is a common phenomenon even in patients who may be considered in "good metabolic control". Therefore, physicians should consider monitoring and targeting postprandial plasma glucose, as well as glycated hemoglobin and fasting plasma glucose, in patients with type 2 diabetes.

Glycemic Control in Coronary Revascularization

OPINION STATEMENT

Hyperglycemia in the setting of coronary revascularization is associated with increased adverse cardiovascular events in patients with or without diabetes mellitus. Data suggest that acute peri-procedural hyperglycemia causes an increase in inflammation, platelet activity, and endothelial dysfunction and is associated with plaque instability and infarct size. While peri-procedural blood glucose level is an independent predictor of adverse outcomes in patients undergoing coronary revascularization, treatment strategies remain uncertain. Randomized clinical trials of glucose-insulin-potassium infusions have consistently shown no benefit, while those comparing insulin therapy versus standard of care have demonstrated mixed results, likely due to the failure to reach euglycemia with these strategies. Although no glucose-lowering agent has been shown to be superior in peri-procedural glycemic control, the continuation of clinically prescribed long-acting glucose-lowering medications in patients with diabetes mellitus prior to coronary angiography and possible percutaneous coronary intervention may be the simplest and most effective approach to maintain euglycemia and decrease the associated increase in inflammation and platelet activity. However, alternative strategies such as therapies targeted at the underlying mechanism of harm (e.g., more potent anti-platelet therapy, anti-inflammatory therapy) should also be considered and warrant further investigation.