Hyperglycemia increases the levels of vascular cellular adhesion molecule-1 and monocyte-chemoattractant-protein-1 in the diabetic endothelial cell

Pathophysiological correlation of arginase-1 in development of type 2 diabetes from obesity in adolescents

BACKGROUND

There is great interest to understand causal pathophysiological correlation between obesity and diabetes mellitus (DM). Vascular endothelial dysfunction is crucially involved in pathogenesis of vascular complications in DM. Recently, increased arginase expression and activity have been described as underlying mechanisms of endothelial dysfunction in DM and vascular inflammation in obesity. By limiting L-arginine bioavailability to endothelial nitric oxide synthase (NOS III), nitric oxide production is potentially impaired.

METHODS

We investigated the impact of plasma from diabetic and obese adolescents on arginase and NOS III expression in cultured human endothelial cells (ECs). A total of 148 male adolescents participated in this study including 18 obese, 28 type 1-, 28 type 2-DM patients, and 74 age-matched healthy volunteers.

RESULTS

A concurrent increase in arginase-1 (1.97-fold) and decrease in NOS III expression (1.45-fold) was observed in ECs exposed to type 2 diabetic plasma compared to control subjects. ECs incubated with type 1 DM plasma had a diminished NOS III level without impact on arginase-1 expression. Urea-assay featured an increased arginase activity in treated ECs with type 1- or 2-DM plasma. Despite increased pro-inflammatory cytokines and chemokines in obese plasma, arginase-1 expression/activity did not change in treated ECs. However, NOS III expression was significantly reduced. Pearson analysis revealed positive correlation between arginase-1, but not NOS III, expression with FBS in ECs treated with type 2-DM plasma.

CONCLUSIONS

Our data demonstrate that increased arginase-1 expression/activity in ECs, as critical pathogenic factor is correlated with development of obesity-related type 2-DM and linked vascular disease.

Aberrant expression of proatherogenic cytokines and growth factors in human umbilical vein endothelial cells from newborns of type 2 diabetic women

Objectives:

This study reports the levels of cytokines, chemokines, and growth factors previously identified as taking part in the pathology of atherosclerosis in human umbilical vein endothelial cells derived from mothers with type 2 diabetes and compares them with those in human umbilical vein endothelial cells derived from healthy mothers under normal glucose conditions.

Methods:

Cytokine analysis measures of human umbilical vein endothelial cell lysates were obtained using a multiple analyte profiling (xMAP) assay based on magnetic bead-based technology, using the MAGPIX instrument. The correlation between cytokines, chemokines, and growth factors was examined statistically in human umbilical vein endothelial cells derived from mothers with type 2 diabetes.

Results:

This study showed that the expression of proinflammatory cytokine interleukin-1 alpha was significantly greater in human umbilical vein endothelial cells derived from mothers with type 2 diabetes than those derived from healthy mothers. The protein level of granulocyte colony-stimulating factor was higher in human umbilical vein endothelial cells derived from mothers with type 2 diabetes than those derived from healthy mothers. A significant positive correlation was demonstrated between the protein expression of granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor in human umbilical vein endothelial cells derived from mothers with type 2 diabetes.

Conclusion:

Diabetes evokes a persistent inflammatory phenotype in human umbilical vein endothelial cells, as indicated by the enhanced production of cytokines and growth factors under normal glucose conditions.

Repurposing metformin for covid-19 complications in patients with type 2 diabetes and insulin resistance

Understanding the exact role of current drugs in Covid-19 disease is essential in the era of global pandemics. Metformin which prescribed as the first-line treatment of type 2 diabetes has beneficial effects on Sars-cov2 infection. These effects are including regulation of immune system, Renin-Angiotensin System and Dipeptidyl Peptidase 4 function in Covid-19 infection. It also activates ACE2, the main receptor of Sars-cov2, in the epithelial cells of respiratory tissue through AMPK signaling and subsequently decreases the rate of viral adhesion. Metformin also declines the adherence of Sars-cov2 to DPP4 (the other receptor of the virus) on T cells. Hence, regulatory effects of metformin on membranous ACE2, and DPP4 can modulate immune reaction against Sars-cov2. Also, immunometabolic effects of metformin on inflammatory cells impair hyper-reactive immune response against the virus through reduction of glycolysis and propagation of mitochondrial oxidation. Metformin also decreases platelet aggravation and risk of thrombosis. In this article, we argue that metformin has beneficial effects on Covid-19 infection in patients with type 2 diabetes and insulin resistance. This opinion should be investigated in future clinical trials.

Novel Anti-inflammatory Effects of Canagliflozin Involving Hexokinase II in Lipopolysaccharide-Stimulated Human Coronary Artery Endothelial Cells

Purpose

Vascular inflammation and disturbed metabolism are observed in heart failure and type 2 diabetes mellitus. Glycolytic enzyme hexokinase II (HKII) is upregulated by inflammation. We hypothesized that SGLT2 inhibitors Canagliflozin (Cana), Empagliflozin (Empa) or Dapagliflozin (Dapa) reduces inflammation via HKII in endothelial cells, and that HKII-dependent inflammation is determined by ERK1/2, NF-κB. and/or AMPK activity in lipopolysaccharide (LPS)-stimulated human coronary artery endothelial cells (HCAECs).

Methods

HCAECs were pre-incubated with 3 μM or 10 μM Cana, 1 μM, 3 μM or 10 μM Empa or 0.5 μM, 3 μM or 10 μM Dapa (16 h) and subjected to 3 h LPS (1 μg/mL). HKII was silenced via siRNA transfection. Interleukin-6 (IL-6) release was measured by ELISA. Protein levels of HK I and II, ERK1/2, AMPK and NF-κB were detected using infra-red western blot.

Results

LPS increased IL-6 release and ERK1/2 phosphorylation; Cana prevented these pro-inflammatory responses (IL-6: pg/ml, control 46 ± 2, LPS 280 ± 154 p < 0.01 vs. control, LPS + Cana 96 ± 40, p < 0.05 vs. LPS). Cana reduced HKII expression (HKII/GAPDH, control 0.91 ± 0.16, Cana 0.71 ± 0.13 p < 0.05 vs. control, LPS 1.02 ± 0.25, LPS + Cana 0.82 ± 0.24 p < 0.05 vs. LPS). Empa and Dapa were without effect on IL-6 release and HKII expression in the model used. Knockdown of HKII by 37% resulted caused partial loss of Cana-mediated IL-6 reduction (pg/ml, control 35 ± 5, LPS 188 ± 115 p < 0.05 vs. control, LPS + Cana 124 ± 75) and ERK1/2 activation by LPS. In LPS-stimulated HCAECs, Cana, but not Empa or Dapa, activated AMPK. AMPK activator A769662 reduced IL-6 release.

Conclusion

Cana conveys anti-inflammatory actions in LPS-treated HCAECs through 1) reductions in HKII and ERK1/2 phosphorylation and 2) AMPK activation. These data suggest a novel anti-inflammatory mechanism of Cana through HKII.

Electronic supplementary material

The online version of this article (10.1007/s10557-020-07083-w) contains supplementary material, which is available to authorized users.

Gene expression changes in arterial and venous endothelial cells exposed to gestational diabetes mellitus

We investigated the molecular changes in fetoplacental blood vessel endothelial cells in gestational diabetes mellitus (GDM). Raw gene expression profile data of arterial and venous endothelial cells from GDM complicated pregnancies and healthy controls were downloaded and used for bioinformatic analysis. There were two differentially expressed genes (DEGs) in venous endothelial cells and 178 DEGs in arterial endothelial cells induced by GDM. The altered genes were clustered to pathways associated with cell cycle, p53 signaling pathway, and cellular senescence. The disease associated gene-pathway network that was constructed comprised eight down-regulated genes (including FBXO5, CCNB1, and CDK1), one up-regulated gene (CCND2), hsa04068: FoxO signaling pathway and hsa04114: Oocyte mitosis pathway. CCND2 was a significant node in the microRNA (miRNA)-target network, which was regulated by seven miRNAs that included hsa-miR-1299, hsa-miR-1200, and hsa-miR-miR-593-5p. FBXO5 was a significant node regulated by two miRNAs. CCND2 and FBXO5 were also the significant nodes in the transcriptional factors-target network and integrated regulatory network. The cell cycle pathway was significantly altered in arterial endothelial cells during GDM, which was involved with the differential expression of CCND2 and FBXO5.

Black mulberry fruit extract alleviates streptozotocin-induced diabetic nephropathy in rats: targeting TNF-α inflammatory pathway

OBJECTIVES

This study was designed to investigate the effect of Morus nigra fruit extract in retarding the progression of diabetic nephropathy in streptozotocin (STZ)-induced diabetic rats.

METHODS

Diabetic male Wistar rats were injected with black mulberry fruit extract (BMFE) at doses of 150 and 300 mg/kg body weight. After 4 weeks, microalbuminuria was estimated in addition to serum concentrations of glucose, insulin, creatinine and albumin.

KEY FINDINGS

The study revealed a significant amelioration of all the measured parameters in diabetic animals. In addition, MDA, lipid peroxide levels and catalase activity were also improved. The histopathological examination of kidney tissues revealed significant improvement of the pathological changes and glomerular sclerosis in diabetic rats treated with BMFE. Treated rats showed downregulation of TNF-α, vascular cell adhesion molecule-1 (VCAM-1) and fibronectin mRNA expression.

CONCLUSION

The ameliorative effect of BMFE on diabetic nephropathy is not only through its potent antioxidant and hypoglycaemic effects but also through its downregulation of TNF-α, VCAM-1 and fibronectin mRNA expression in renal tissues of diabetic-treated rats. Therefore, BMFE as dietary supplement could be a promising agent in improving diabetic nephropathy.

Metformin attenuates adhesion between cancer and endothelial cells in chronic hyperglycemia by recovery of the endothelial glycocalyx barrier

BACKGROUND

Epidemiologic studies suggest that diabetes is associated with an increased risk of cancer. Concurrently, clinical trials have shown that metformin, which is a first-line antidiabetic drug, displays anticancer activity. The underlying mechanisms for these effects are, however, still not well recognized.

METHODS

Methods based on atomic force microscopy (AFM) were used to directly evaluate the influence of metformin on the nanomechanical and adhesive properties of endothelial and cancer cells in chronic hyperglycemia. AFM single-cell force spectroscopy (SCFS) was used to measure the total adhesion force and the work of detachment between EA.hy926 endothelial cells and A549 lung carcinoma cells. Nanoindentation with a spherical AFM probe provided information about the nanomechanical properties of cells, particularly the length and grafting density of the glycocalyx layer. Fluorescence imaging was used for glycocalyx visualization and monitoring of E-selectin and ICAM-1 expression.

RESULTS

SCFS demonstrated that metformin attenuates adhesive interactions between EA.hy926 endothelial cells and A549 lung carcinoma cells in chronic hyperglycemia. Nanoindentation experiments, confirmed by confocal microscopy imaging, revealed metformin-induced recovery of endothelial glycocalyx length and density. The recovery of endothelial glycocalyx was correlated with a decrease in the surface expression of E-selectin and ICAM-1.

CONCLUSION

Our results identify metformin-induced endothelial glycocalyx restoration as a key factor responsible for the attenuation of adhesion between EA.hy926 endothelial cells and A549 lung carcinoma cells.

GENERAL SIGNIFICANCE

Metformin-induced glycocalyx restoration and the resulting attenuation of adhesive interactions between the endothelium and cancer cells may account for the antimetastatic properties of this drug.

Levels of soluble cell adhesion molecules in type 2 diabetes mellitus patients with macrovascular complications

Objective

Type 2 diabetes mellitus (T2DM) is a main risk factor for development of cardiovascular diseases (CVDs) and endothelial dysfunction. This study aimed to investigate serum levels of soluble vascular cell adhesion molecule 1 (sVCAM-1), intercellular adhesion molecule 1 (sICAM-1), and endothelium selectin (sE-selectin) in T2DM patients with macrovascular complications.

Methods

A cross-sectional study of 21 controls, 30 T2DM patients without CVDs, and 30 T2DM patients with CVDs was conducted. Serum levels of soluble adhesion molecules including sVCAM-1, sICAM-1, and sE-selectin were determined using ELISA.

Results

Serum levels of sVCAM-1, sICAM-1, and sE-selectin were higher in T2DM patients than in controls. Levels of serum sVCAM-1 were higher in T2DM patients with CVDs compared with T2DM patients without CVDs. In T2DM patients with CVDs, significant positive associations were observed between sVCAM-1, sICAM-1, and sE-selectin levels (r = 0.575, p = 0.001 and r = 0.378, p = 0.040).

Conclusions

Circulating levels of soluble adhesion molecules were elevated in T2DM patients, regardless of whether the patients had cardiovascular complications. Only sVCAM-1 was considered a useful marker for the prediction of CVDs in T2DM patients.

The Role of Butyrate on Monocyte Migration and Inflammation Response in Patient with Type 2 Diabetes Mellitus

Type 2 Diabetes Mellitus (T2DM) is a very serious global problem. In Indonesia, this disease attacks at the most productive age; consequently, it can reduce economic status and life expectancy. The pathogenesis of T2DM is very closely related to inflammation and macrophage accumulation. However, no anti-inflammatory agent has been proven to play a role in the management of T2DM. Butyrate is a short chain fatty acid produced from resistant starch fermentation in the intestinal lumen. It is able to bind to GPR41 and GPR43 receptors on monocytes, so that it can change the pattern of cytokine expression, activation, migration and cell differentiation. Hence, it is interesting to examine the anti-inflammation effect of butyrate and the effect on monocyte migration. A total of 37 subjects were examined in this study. They were divided into two groups, with and without butyrate treatment. We analyzed two pro-inflammatory cytokines (Tumor Necrosis Factor TNF-α and Interleukin IL-6) and one anti-inflammatory cytokine, IL 10. Monocytes were isolated in type 1 collagen gel for migration testing using the µ-slide chemotaxis IBIDI. Image analysis used ImageJ and Chemotaxis tool software. There was a significant difference in the TNFα/IL 10 ratio between healthy groups and T2DM. Butyrate also appears to suppress TNFα cytokine production and increase IL10 production. It also decreases the accumulation distance of monocyte migration in T2DM.

Glomerular function in relation to circulating adhesion molecules and inflammation markers in a general population

Background

Inflammation is a hallmark of chronic kidney disease (CKD) and stimulates glomerular expression of vascular adhesion molecules (VCAMs). We investigated in a general population whether estimated glomerular filtration rate (eGFR) is associated with circulating adhesion molecules, inflammation markers or both.

Methods

We measured serum levels of five adhesion molecules [VCAM-1, intracellular adhesion molecule-1 (ICAM-1), P-selectin, E-selectin and monocyte chemoattractant protein-1 (MCP-1)] and seven inflammation markers [C-reactive protein (CRP), neutrophil gelatinase-associated lipocalin (NGAL), tumour necrosis factor receptor 1 (TNF-R1), TNF-α, interleukin 6 (IL-6), IL-8 and vascular endothelial growth factor] in 1338 randomly recruited people (50.8% women, mean age 51.7 years, eGFR 79.9 mL/min/1.73 m²).

Results

In multivariable-adjusted analyses, eGFR decreased (P ≤ 0.004) with higher VCAM-1 (association size expressed in mL/min/1.73 m² for a doubling of the marker, −2.99), MCP-1 (−1.19), NGAL (−1.19), TNF receptor 1 (−2.78), TNF-α (−2.28) and IL-6 (−0.94). The odds ratios of having eGFR <60 versus ≥60 mL/min/1.73 m² (n = 138 versus 1200) were significant (P ≤ 0.001) for VCAM-1 (1.77), MCP-1 (1.32), NGAL (1.26), TNF-R1 (1.49), TNF-α (1.45) and IL-6 (1.20). Compared with 24-h albuminuria, VCAM-1 increased (P <0.0001) the area under the curve from 0.57 to 0.65, MCP-1 to 0.67 and TNF-R1 to 0.79, but TNF-R1 outperformed both adhesion molecules (P < 0.0001).

Conclusions

In a general population, eGFR is inversely associated with circulating adhesion molecules VCAM-1 and MCP-1 and several inflammation markers, but inflammation markers, in particular TNF-R1 and TNF-α, identify patients with eGFR <60 mL/min/1.73 m² more accurately.

Human fetoplacental arterial and venous endothelial cells are differentially programmed by gestational diabetes mellitus, resulting in cell-specific barrier function changes

AIMS/HYPOTHESIS

An adverse intrauterine environment can result in permanent changes in the physiology of the offspring and predispose to diseases in adulthood. One such exposure, gestational diabetes mellitus (GDM), has been linked to development of metabolic disorders and cardiovascular disease in offspring. Epigenetic variation, including DNA methylation, is recognised as a leading mechanism underpinning fetal programming and we hypothesised that this plays a key role in fetoplacental endothelial dysfunction following exposure to GDM. Thus, we conducted a pilot epigenetic study to analyse concordant DNA methylation and gene expression changes in GDM-exposed fetoplacental endothelial cells.

METHODS

Genome-wide methylation analysis of primary fetoplacental arterial endothelial cells (AEC) and venous endothelial cells (VEC) from healthy pregnancies and GDM-complicated pregnancies in parallel with transcriptome analysis identified methylation and expression changes. Most-affected pathways and functions were identified by Ingenuity Pathway Analysis and validated using functional assays.

RESULTS

Transcriptome and methylation analyses identified variation in gene expression linked to GDM-associated DNA methylation in 408 genes in AEC and 159 genes in VEC, implying a direct functional link. Pathway analysis found that genes altered by exposure to GDM clustered to functions associated with 'cell morphology' and 'cellular movement' in healthy AEC and VEC. Further functional analysis demonstrated that GDM-exposed cells had altered actin organisation and barrier function.

CONCLUSIONS/INTERPRETATION

Our data indicate that exposure to GDM programs atypical morphology and barrier function in fetoplacental endothelial cells by DNA methylation and gene expression change. The effects differ between AEC and VEC, indicating a stringent cell-specific sensitivity to adverse exposures associated with developmental programming in utero.

DATA AVAILABILITY

DNA methylation and gene expression datasets generated and analysed during the current study are available at the National Center for Biotechnology Information (NCBI) Gene Expression Omnibus (GEO) database ( http://www.ncbi.nlm.nih.gov/geo ) under accession numbers GSE106099 and GSE103552, respectively.

Discovery of pancreastatin inhibitor PSTi8 for the treatment of insulin resistance and diabetes: studies in rodent models of diabetes mellitus

Pancreastatin (PST) is an endogenous peptide which regulates glucose and lipid metabolism in liver and adipose tissues. In type 2 diabetic patients, PST level is high and plays a crucial role in the negative regulation of insulin sensitivity. Novel therapeutic agents are needed to treat the diabetes and insulin resistance (IR) against the PST action. In this regard, we have investigated the PST inhibitor peptide-8 (PSTi8) action against diabetogenic PST. PSTi8 rescued PST-induced IR in HepG2 and 3T3L1 cells. PSTi8 increases the GLUT4 translocation to cell surface to promote glucose uptake in L6-GLUT4myc cells. PSTi8 treatment showed an increase in insulin sensitivity in db/db, high fat and fructose fed streptozotocin (STZ) induced IR mice. PSTi8 improved the glucose homeostasis which is comparable to metformin in diabetic mice, characterized by elevated glucose clearance, enhanced glycogenesis, enhanced glycolysis and reduced gluconeogenesis. PST and PSTi8 both were docked to the GRP78 inhibitor binding site in protein-protein docking, GRP78 expression and its ATPase activity studies. The mechanism of action of PSTi8 may be mediated by activating IRS1/2-phosphatidylinositol-3-kinase-AKT (FoxO1, Srebp-1c) signaling pathway. The discovery of PSTi8 provides a promising therapeutic agent for the treatment of metabolic diseases mainly diabetes.

The effects of glucose concentrations associated with lipopolysaccharide and interferon-gamma stimulus on mediators' production of RAW 264.7 cells

Diabetes mellitus (DM) is a metabolic disorder that results in the impairment of the metabolism of carbohydrates, proteins and lipids. It can give rise to various complications, mainly caused by chronic exposure of cells to high glucose concentrations, including changes in the immune response processes. The aim of this study was to verify the chemokine and cytokines production profile in the presence of different glucose concentrations and infection/inflammatory stimuli. To this end, cell viability and the production of chemokines, cytokines and nitric oxide (NO) were analyzed in RAW 264.7 cell culture. Results demonstrated that there was no change in cell viability after 6, 24 and 72 h. Different stimuli were unable to modify the monocyte chemoattractant protein (MCP)-1 and tumor necrosis factor (TNF)-α production. Groups stimulated with lipopolysaccharides (LPS) and LPS and recombinant interferon (rIFN)-γ down-regulated interleukin (IL)-1α, IL-10 and IL-12 and up-regulated IL-6 production. NO production maintained a pattern of increase, according to the increase in glucose concentrations, reaching its peak at 72 h. In summary, the results demonstrated that high glucose concentrations alone may be sufficient to alter the in vitro mediators' production of RAW 264.7 cells.

Krüppel-Like Factors in Vascular Inflammation: Mechanistic Insights and Therapeutic Potential

The role of inflammation in vascular disease is well recognized, involving dysregulation of both circulating immune cells as well as the cells of the vessel wall itself. Unrestrained vascular inflammation leads to pathological remodeling that eventually contributes to atherothrombotic disease and its associated sequelae (e.g., myocardial/cerebral infarction, embolism, and critical limb ischemia). Signaling events during vascular inflammation orchestrate widespread transcriptional programs that affect the functions of vascular and circulating inflammatory cells. The Krüppel-like factors (KLFs) are a family of transcription factors central in regulating vascular biology in states of homeostasis and disease. Given their abundance and diversity of function in cells associated with vascular inflammation, understanding the transcriptional networks regulated by KLFs will further our understanding of the pathogenesis underlying several pervasive health concerns (e.g., atherosclerosis, stroke, etc.) and consequently inform the treatment of cardiovascular disease. Within this review, we will discuss the role of KLFs in coordinating protective and deleterious responses during vascular inflammation, while addressing the potential targeting of these critical transcription factors in future therapies.

The Effects of Diabetes Induction on the Rat Heart: Differences in Oxidative Stress, Inflammatory Cells, and Fibrosis between Subendocardial and Interstitial Myocardial Areas

Diabetic cardiomyopathy (DCM) is characterized by cardiac remodeling and impaired diastolic function that may lead to heart failure. The aim of this study was to evaluate oxidative stress, inflammatory cells, and fibrosis in both subendocardial (SEN) and interstitial (INT) areas of the myocardium. Male Wistar rats were allocated to 2 groups of 9 animals, a control (CT) group and streptozotocin-induced diabetes (DM). After 8 weeks, echocardiography morphometry, protein expression, and confocal microscopy in SEN and INT areas of the left ventricle (LV) were performed. The echocardiographic analysis showed that diabetes induction leads to cardiac dilation, hypertrophy, and LV diastolic dysfunction. As compared to CT, the induction of diabetes increased inflammatory cells and fibrosis in both SEN and INT areas of DM myocardium and increased ROS generation only in SEN. Comparing the SEN and INT areas in the DM group, inflammatory cells and fibrosis in SEN were greater than in INT. In conclusion, diabetic myocardium SEN area, wherein oxidative stress was more pronounced, is more susceptible to cardiac dysfunction than INT area. This finding can be important for the understanding of the heart remodeling process occurring in DCM and perhaps to engender targeted therapies to attenuate or revert DCM-related diastolic dysfunction.

Danhong Huayu Koufuye Prevents Diabetic Retinopathy in Streptozotocin-Induced Diabetic Rats via Antioxidation and Anti-Inflammation

Danhong Huayu Koufuye (DHK), a traditional Chinese prescription, is used to treat central retinal vein occlusion clinically. We previously reported that DHK prevented diabetic retinopathy (DR) in rats. Moreover, we found that it protected endothelial cells from hyperglycemia-induced apoptosis through antioxidation and anti-inflammation. Here, we investigated whether antioxidative and anti-inflammatory activities of DHK contributed to its therapeutic effect on DR in streptozotocin- (STZ-) induced diabetic rats. DHK significantly blocked the breakdown of the blood-retinal barrier (BRB) and increased the thickness of the inner nuclear layer (INL), as well as suppressed the swelling of the ganglion cell layer (GCL) in diabetic retinas. DHK remarkably increased the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) in plasma, and decreased serum level of nitric oxide (NO). Moreover, DHK markedly reduced the serum levels of vascular endothelial growth factor (VEGF) and intercellular adhesion molecule-1 (ICAM-1). Furthermore, DHK significantly downregulated protein expressions of VEGF and inducible NO synthase (iNOS) and mRNA expression of ICAM-1 in retinas. These results suggest that the antioxidative and anti-inflammatory activities of DHK may be important mechanisms involved in the protective effect of DHK on DR in STZ-induced diabetic rats.

CLIC1 Inhibition Attenuates Vascular Inflammation, Oxidative Stress, and Endothelial Injury

Endothelial dysfunction, which includes endothelial oxidative damage and vascular inflammation, is a key initiating step in the pathogenesis of atherosclerosis (AS) and an independent risk factor for this disorder. Intracellular chloride channel 1 (CLIC1), a novel metamorphic protein, acts as a sensor of cell oxidation and is involved in inflammation. In this study, we hypothesize that CLIC1 plays an important role in AS. Apolipoprotein E-deficient mice were supplied with a normal diet or a high-fat and high-cholesterol diet for 8 weeks. Overexpressed CLIC1 was associated with the accelerated atherosclerotic plaque development, amplified oxidative stress, and in vivo release of inflammatory cytokines. We subsequently examined the underlying molecular mechanisms through in vitro experiments. Treatment of cultured human umbilical vein endothelial cells (HUVECs) with H2O2 induced endothelial oxidative damage and enhanced CLIC1 expression. Suppressing CLIC1 expression through gene knocked-out (CLIC1-/-) or using the specific inhibitor indanyloxyacetic acid-94 (IAA94) reduced ROS production, increased SOD enzyme activity, and significantly decreased MDA level. CLIC1-/- HUVECs exhibited significantly reduced expression of TNF-α and IL-1β as well as ICAM-1 and VCAM-1 at the protein levels. In addition, H2O2 promoted CLIC1 translocation to the cell membrane and insertion into lipid membranes, whereas IAA94 inhibited CLIC1 membrane translocation induced by H2O2. By contrast, the majority of CLIC1 did not aggregate on the cell membrane in normal HUVECs, and this finding is consistent with the changes in cytoplasmic chloride ion concentration. This study demonstrates for the first time that CLIC1 is overexpressed during AS development both in vitro and in vivo and can regulate the accumulation of inflammatory cytokines and production of oxidative stress. Our results also highlight that deregulation of endothelial functions may be associated with the membrane translocation of CLIC1 and active chloride-selective ion channels in endothelial cells.

Broad Infiltration of Macrophages Leads to a Proinflammatory State in Streptozotocin-Induced Hyperglycemic Mice

Chronic diseases are often associated with altered inflammatory response, leading to increased host vulnerability to new inflammatory challenges. Employing streptozotocin (STZ)-induced diabetes as a model, we further investigate mechanisms leading to enhanced neutrophil (polymorphonuclear leukocytes [PMN]) responses under hyperglycemia and compare them with those under chronic colitis. We show that, different from colitis under which the PMN response is significantly potentiated, the existence of a proinflammatory state associated with broad increases in macrophages in various organs plays a dominant role in promoting the PMN inflammatory response in diabetic mice. Studies of PMN infiltration during zymosan-induced peritonitis reveal that hyperglycemia enhances PMN recruitment not through inducing a high level of IL-17, which is the case in colitis, but through increasing F4/80⁺ macrophages in the peritoneal cavity, resulting in elevations of IL-6, IL-1β, TNF-α, and CXCL1 production. Insulin reversal of hyperglycemia, but not the neutralization of IL-17, reduces peritoneal macrophage numbers and ameliorates PMN infiltration during peritonitis. Significantly increased macrophages are also observed in the liver, kidneys, and intestines under hyperglycemia, and they are attributable to exacerbated nephropathy and colitis when inflammatory conditions are induced by doxorubicin and dextran sulfate sodium, respectively. Furthermore, analyses of monocyte production and macrophage proliferation in tissues suggest that significant monocytosis of inflammatory F4/80⁺Gr-1⁺ monocytes from the spleen and macrophage proliferation in situ synergistically contribute to the increased macrophage population under hyperglycemia. In conclusion, our results demonstrate that STZ-induced hyperglycemic mice develop a systemic proinflammatory state mediated by broad infiltration of macrophages.

Comparative effects of acute hypoglycemia and hyperglycemia on pro-atherothrombotic biomarkers and endothelial function in non-diabetic humans

BACKGROUND

The comparative effects of acute moderate hyperglycemia and hypoglycemia on in vivo endothelial function together with pro-inflammatory and pro-atherothrombotic responses in healthy individuals have not been determined.

METHODS

To investigate this question, 45 healthy subjects were compared during glucose clamp studies consisting of euinsulinemic hyperglycemia and hyperinsulinemic hyperglycemia (plasma glucose 11.1mmol/L, both with pancreatic clamps) and hyperinsulinemic euglycemia and hyperinsulinemic hypoglycemia (plasma glucose 5.1 and 2.9mmol/L, respectively). Two-dimensional Doppler ultrasound was used to determine brachial artery endothelial function.

RESULTS

Insulin levels during euinsulinemia hyperglycemia were 194±23 and (850±49-988±114) pmol/L during all hyperinsulinemic protocols. Responses of VCAM-1, ICAM-1, E-selectin, P-selectin, PAI-1, and IL-6 were increased (p<0.05-0.0001) during euinsulinemic hyperglycemia or hypoglycemia as compared to hyperinsulinemic euglycemia or hyperinsulinemic hyperglycemia. PAI-1 was increased (p<0.04) during hypoglycemia as compared to euinsulinemic hyperglycemia, and TNF-α responses were also increased during hypoglycemia as compared to hyperinsulinemic euglycemia or hyperinsulinemic hyperglycemia (p<0.05). In vivo endothelial function was similarly blunted by acute moderate hyperglycemia or hypoglycemia.

CONCLUSION

In summary, acute moderate hypoglycemia and euinsulinemic hyperglycemia can result in similar endothelial dysfunction and pro-atherothrombotic responses. Fibrinolytic balance was reduced by a greater extent by hypoglycemia as compared to moderate hyperglycemia. Acutely, hyperinsulinemia can prevent the acute pro-atherothrombotic and pro-inflammatory effects of moderate hyperglycemia but not hypoglycemia.

Anti-inflammatory properties of resveratrol in the retinas of type 2 diabetic rats

Resveratrol (trans-3,5,4'-trihydroxystilbene) is a nutritional supplement with anti-inflammatory properties. The present study investigated the long-term anti-inflammatory property of resveratrol in the retinas of type 2 diabetic rats. Male Wistar rats were divided into four groups: normal control, diabetic control, resveratrol-treated normal rats and resveratrol-treated diabetic rats. Type 2 diabetes was induced by a single dose injection of streptozotocin (50 mg/kg; i.p.) 15 min after the administration of nicotinamide (110 mg/kg; i.p.) in 12-h fasted rats (the streptozotocin-nicotinamide type 2 diabetic model). Oral resveratrol administration (5 mg/kg per day for 4 months) significantly improved glucose tolerance, and alleviated hyperglycemia and weight loss in diabetic rats. Furthermore, resveratrol administration significantly decreased the elevated levels of nuclear factor-κB activity, and mRNA expression, tumour necrosis factor alpha level and apoptotic cells in the retinas of the diabetic rats. Furthermore, resveratrol did not significantly affect plasma insulin levels. Long-term resveratrol administration has beneficial anti-inflammatory properties in a rat model of diabetes. However, whether resveratrol exerts its effects directly or through reducing blood glucose levels requires further investigation.

Acute effects of hyperinsulinemia and hyperglycemia on vascular inflammatory biomarkers and endothelial function in overweight and obese humans

We investigated the separate and combined effects of hyperglycemia and hyperinsulinemia on markers of endothelial function, proinflammatory and proatherothrombotic responses in overweight/obese nondiabetic humans. Twenty-two individuals (13 F/9 M, BMI 30.1 ± 4.1 kg/m(2)) were studied during four randomized, single-blind protocols. The pancreatic clamp technique was combined with 4-h glucose clamps consisting of either 1) euinsulinemia-euglycemia, 2) euinsulinemia-hyperglycemia, 3) hyperinsulinemia-hyperglycemia, or 4) hyperinsulinemia-euglycemia. Insulin levels were higher (998 ± 66 vs. 194 ± 22 pmol/l) during hyperinsulinemia compared with euinsulinemia. Glucose levels were 11.1 mmol/l during hyperinsulinemia compared with 5.1 ± 0.1 mmol/l during euglycemia. VCAM, ICAM, P-selectin, E-selectin, IL-6, adiponectin, and PAI-1 responses were all increased (P < 0.01-0.0001), and endothelial function was decreased (P < 0.0005) during euinsulinemia-hyperglycemia compared with other protocols. Hyperinsulinemia in the presence of hyperglycemia prevented the increase in proinflammatory and proatherothrombotic markers while also normalizing vascular endothelial function. We conclude that 4 h of moderate hyperglycemia can result in increases of proinflammatory markers (ICAM, VCAM, IL-6, E-selectin), platelet activation (P-selectin), reduced fibrinolytic balance (increased PAI-1), and disordered endothelial function in a group of obese and overweight individuals. Hyperinsulinemia prevents the actions of moderate hyperglycemia to reduce endothelial function and increase proinflammatory and proatherothrombotic markers.

Vascular cell adhesion molecule-1, but not intercellular adhesion molecule-1, is associated with diabetic kidney disease in Asians with type 2 diabetes

BACKGROUND AND AIMS

The association of adhesion molecules ICAM-1 and VCAM-1 with cardiovascular diseases has been well-studied. However, their roles in diabetic kidney disease (DKD) are incompletely understood. We aim to study the association of plasma ICAM-1 and VCAM-1 with DKD in Asians with type 2 diabetes (T2DM).

SUBJECTS AND METHODS

A total of 1950 Asians with T2DM were included in this cross-sectional study. Plasma ICAM-1 and VCAM-1 were measured by immunoassays.

RESULTS

Renal filtration function (eGFR) declined and urinary albumin-to-creatinine ratio (ACR) levels increased progressively with the increase in plasma VCAM-1 levels. In contrast, no significant changes in eGFR and ACR were observed in subjects across different plasma ICAM-1 levels. Both ICAM-1 and VCAM-1 were correlated with ACR (rho = 0.153, p < 0.001 for VCAM-1 and ACR; rho = 0.053, p = 0.020 for ICAM-1 and ACR) in bivariate correlation analysis. However, only VCAM-1 was correlated with eGFR (rho = -0.228, p < 0.001). Multivariable linear regression models revealed that VCAM-1, but not ICAM-1, was independently associated with eGFR and albuminuria. Backward linear regression suggested that plasma VCAM-1 variability was mainly determined by eGFR whereas plasma ICAM-1 level was mainly determined by C-reactive protein in patients with T2DM.

CONCLUSIONS

Plasma VCAM-1 level, but not ICAM-1 level, was independently associated with prevalent DKD in Asians with T2DM. High level of ICAM-1 may be indicative of systemic inflammation and portends increase risk of incipient DKD.

Circulating cell-free mitochondrial DNA as the probable inducer of early endothelial dysfunction in the prediabetic patient

Recent evidence has shown that 346million people in the world have diabetes mellitus (DM); this number will increase to 439million by 2030. In addition, current data indicate an increase in DM cases in the population between 40 and 59years of age. Diabetes is associated with the development of micro- and macro-vascular complications, derived from chronic hyperglycemia on the endothelium. Some reports demonstrate that people in a prediabetic state have a major risk of developing early endothelial dysfunction (ED). Today, it is accepted that individuals considered as prediabetic patients are in a pro-inflammatory state associated with endothelial and mitochondrial dysfunction. It is important to mention that impaired mitochondrial functionality has been linked to endothelial apoptosis and release of mitochondrial DNA (mtDNA) in patients with sepsis, cardiac disease, or atherosclerosis. This free mtDNA could promote ED, as well as other side effects on the vascular system through the activation of the toll-like receptor 9 (TLR9). TLR9 is expressed in different cell types (e.g., T or B lymphocytes, mastocytes, and epithelial and endothelial cells). It is localized intracellularly and recognizes non-methylated dinucleotides of viral, bacterial, and mitochondrial DNA. Recently, it has been reported that TLR9 is associated with the pathogenesis of lupus erythematosus, rheumatoid arthritis, and autoimmune diabetes. In this work, it is hypothesized that the increase in the levels of circulating mtDNA is the trigger of early ED in the prediabetic patient, and later on in the older patient with diabetes, through activation of the TLR9 present in the endothelium.

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

Background and Objectives

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

Methods

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

Results

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

Conclusion

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

Brazilin ameliorates high glucose-induced vascular inflammation via inhibiting ROS and CAMs production in human umbilical vein endothelial cells

Vascular inflammatory process has been suggested to play a key role in the initiation and progression of atherosclerosis, a major complication of diabetes mellitus. Recent studies have shown that brazilin exhibits antihepatotoxic, antiplatelet, cancer preventive, or anti-inflammatory properties. Thus, we investigated whether brazilin suppresses vascular inflammatory process induced by high glucose (HG) in cultured human umbilical vein endothelial cells (HUVEC). HG induced nitrite production, lipid peroxidation, and intracellular reactive oxygen species formation in HUVEC cells, which was reversed by brazilin. Western blot analysis revealed that brazilin markedly inhibited HG-induced phosphorylation of endothelial nitric oxide synthase. Besides, we investigated the effects of brazilin on the MAPK signal transduction pathway because MAPK families are associated with vascular inflammation under stress. Brazilin blocked HG-induced phosphorylation of extracellular signal-regulated kinase and transcription factor NF-κB. Furthermore, brazilin concentration-dependently attenuated cell adhesion molecules (ICAM-1 and VCAM-1) expression induced by various concentrations of HG in HUVEC. Taken together, the present data suggested that brazilin could suppress high glucose-induced vascular inflammatory process, which may be closely related with the inhibition of oxidative stress, CAMs expression, and NF-κB activation in HUVEC. Our findings may highlight a new therapeutic intervention for the prevention of vascular diseases.

Resveratrol ameliorates diabetic vascular inflammation and macrophage infiltration in db/db mice by inhibiting the NF-κB pathway

In this study, resveratrol (RSV) - a potent sirtuin 1 activator - was found to have beneficial effects on glucolipid metabolism and improve inflammatory mediators and markers of oxidative stress. Diabetic (db/db) mice and non-diabetic C57BL/6J mice were used in the study. The db/db mice were treated with or without 0.3% RSV mixed with chow for 8 weeks. Dietary RSV significantly lowered blood glucose, plasma lipid and free fatty acid levels in db/db mice. RSV markedly inhibited the expression of intercellular adhesion molecule-1 (ICAM-1), endothelial vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1) in the aorta and the blood plasma of db/db mice (p < 0.05). Levels of mac-3-positive macrophages (measure of the infiltration of activated macrophages) were lower in RSV-treated diabetic mice than in their untreated counterparts (p < 0.05). RSV treatment reduced the activity of the transcriptional regulator nuclear factor kappa B (NF-κB) in aortic tissues (p < 0.05). Thus, RSV treatment reduced ICAM-1, VCAM-1 and MCP-1 expression in the aorta and ICAM-1, VCAM-1 and MCP-1 levels in the plasma of diabetic mice. Since dietary supplementation with RSV also reduced NF-κB activities in the aorta, the therapeutic effects of RSV might be associated with the downregulation of NF-κB.

Dietary quality in a sample of adults with type 2 diabetes mellitus in Ireland; a cross-sectional case control study

Background

A number of dietary quality indices (DQIs) have been developed to assess the quality of dietary intake. Analysis of the intake of individual nutrients does not reflect the complexity of dietary behaviours and their association with health and disease. The aim of this study was to determine the dietary quality of individuals with type 2 diabetes mellitus (T2DM) using a variety of validated DQIs.

Methods

In this cross-sectional analysis of 111 Caucasian adults, 65 cases with T2DM were recruited from the Diabetes Day Care Services of St. Columcille’s and St. Vincent’s Hospitals, Dublin, Ireland. Forty-six controls did not have T2DM and were recruited from the general population. Data from 3-day estimated diet diaries were used to calculate 4 DQIs.

Results

Participants with T2DM had a significantly lower score for consumption of a Mediterranean dietary pattern compared to the control group, measured using the Mediterranean Diet Score (Range 0–9) and the Alternate Mediterranean Diet Score (Range 0–9) (mean ± SD) (3.4 ± 1.3 vs 4.8 ± 1.8, P < 0.001 and 3.3 ± 1.5 vs 4.2 ± 1.8, P = 0.02 respectively). Participants with T2DM also had lower dietary quality than the control population as assessed by the Healthy Diet Indicator (Range 0–9) (T2DM; 2.6 ± 2.3, control; 3.3 ± 1.1, P = 0.001). No differences between the two groups were found when dietary quality was assessed using the Alternate Healthy Eating Index. Micronutrient intake was assessed using the Micronutrient Adequacy Score (Range 0–8) and participants with T2DM had a significantly lower score than the control group (T2DM; 1.6 ± 1.4, control; 2.3 ± 1.4, P = 0.009). When individual nutrient intakes were assessed, no significant differences were observed in macronutrient intake.

Conclusion

Overall, these findings demonstrate that T2DM was associated with a lower score when dietary quality was assessed using a number of validated indices.

Effect of different degrees of impaired glucose metabolism on the expression of inflammatory markers in monocytes of patients with atherosclerosis

Inflammatory markers are elevated in type 2 diabetic patients (DP) and may predict the development of type 2 diabetes. Our aims were to analyze differences in the expression of inflammatory and immunological molecules between DP and healthy subjects and to investigate whether glycemic control might prevent the overexpression of inflammatory markers in DP. Twenty-two DP with advanced atherosclerosis and eight healthy blood donors were included. DP were classified as well (HbA1c ≤ 6.5) or poorly controlled (HbA1c > 6.5). In "in vitro" studies, monocytes were exposed to low (5.5 mM) or high glucose (26 mM) concentrations in the absence or presence of insulin. Expression profiling of 14 inflammatory genes was analyzed using TLDA analysis. "In vivo" results show that monocytes from DP had increased levels of monocyte chemoattractant protein (MCP-1) and interleukin 6 (IL6) and lower levels of Toll-like receptor 2 (TLR2) mRNA than healthy subjects. Well-controlled DP had lower levels of IL-6 than poorly controlled DP, suggesting that glycemic control may prevent IL6 mRNA alterations associated with diabetes. "In vitro" results demonstrate that glucose directly and significantly induced MCP-1 and IL6 and reduced TLR2 mRNA expression. Insulin at high dose (100 IU/ml) dramatically enhanced the upregulatory effects of glucose on MCP-1 and IL-6 and reduced per se TLR2 mRNA expression. MCP-1, IL-6 and TLR2 are key inflammatory players altered in monocytes from type 2 DP. Both hyperinsulinemia and hyperglycemia contribute to alter the expression of these genes. The glycemic control only significantly prevented IL6 overexpression in this group of patients.

The feto-placental endothelium in pregnancy pathologies

This review aims to provide a comprehensive summary of the aspects of endothelial and vascular dysfunction in the feto-placental vasculature occurring in pregnancy pathologies. This endothelium is continuous with the fetal circulation. Its function and potential dysfunction in pathologies will have a profound impact on fetal development. Gestational diabetes mellitus represents one of these pathologies, in which its associated metabolic derangements will alter feto-placental endothelial functions. These, in turn, may result in functional changes of the placenta, which may entail impaired fetal development. By contrast, changes in the feto-placental vasculature observed in cases of fetal growth restriction and preeclampsia may be causative (fetal growth restriction) or secondary (preeclampsia) for the pathology.

Monocyte Chemoattractant Protein 1 (MCP-1) in obesity and diabetes

Monocyte Chemoattractant Protein-1 (MCP-1) is the first discovered and most extensively studied CC chemokine, and the amount of studies on its role in the etiologies of obesity- and diabetes-related diseases have increased exponentially during the past two decades. This review attempted to provide a panoramic perspective of the history, regulatory mechanisms, functions, and therapeutic strategies of this chemokine. The highlights of this review include the roles of MCP-1 in the development of obesity, diabetes, cardiovascular diseases, insulitis, diabetic nephropathy, and diabetic retinopathy. Therapies that specifically or non-specifically inhibit MCP-1 overproduction have been summarized.

Modulation of diabetic retinopathy pathophysiology by natural medicines through PPAR-γ-related pharmacology

Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes and remains a major cause of preventable blindness among adults at working age. DR involves an abnormal pathology of major retinal cells, including retinal pigment epithelium, microaneurysms, inter-retinal oedema, haemorrhage, exudates (hard exudates) and intraocular neovascularization. The biochemical mechanisms associated with hyperglycaemic-induced DR are through multifactorial processes. Peroxisome proliferator-activated receptor-γ (PPAR-γ) plays an important role in the pathogenesis of DR by inhibiting diabetes-induced retinal leukostasis and leakage. Despite DR causing eventual blindness, only a few visual or ophthalmic symptoms are observed until visual loss develops. Therefore, early medical interventions and prevention are the current management strategies. Laser photocoagulation therapy is the most common treatment. However, this therapy may cause retinal damage and scarring. Herbal and traditional natural medicines may provide an alternative to prevent or delay the progression of DR. This review provides an analysis of the therapeutic potential of herbal and traditional natural medicines or their active components for the slowdown of progression of DR and their possible mechanism through the PPAR-γ pathway.

Surface-expressed enolase contributes to the adhesion of Paracoccidioides brasiliensis to host cells

Paracoccidioidomycosis is a systemic mycosis caused by the dimorphic fungus Paracoccidioides brasiliensis. Understanding the interactions between P. brasiliensis and the host tissue depends on the study of the different steps of the process of colonization, especially adhesion, in which the pathogen recognizes ligands on the surface of host cells. This study aimed to verify the role of enolase in the host cell-fungus interaction and the ability of enolase to bind to extracellular matrix components, to determine its subcellular localization, and to study the P. brasiliensis enolase amino acid sequence. The data revealed that fibronectin is the major ligand of enolase. Evaluation of the location of enolase at an ultrastructural level revealed that it is distributed in various cellular compartments, but at a high level in the cell wall. The analysis of the amino acid sequence revealed an internal plasminogen-binding motif ((254)FYKADEKKY(262)), which is conserved in most organisms and described as an important interaction site of the enolase with the host cell surface. This suggests that enolase performs additional functions related to the glycolytic pathway and also plays a role of adhesion in P. brasiliensis. Therefore, this study increases the knowledge about the characteristics of enolase and its influence on the binding process of P. brasiliensis.

MicroRNAs mediate metabolic stresses and angiogenesis

MicroRNAs are short endogenous RNA molecules that are able to regulate (mainly inhibiting) gene expression at the post-transcriptional level. The MicroRNA expression profile is cell-specific, but it is sensitive to perturbations produced by stresses and diseases. Endothelial cells subjected to metabolic stresses, such as calorie restriction, nutrients excess (glucose, cholesterol, lipids) and hypoxia may alter their functionality. This is predictive for the development of pathologies like atherosclerosis, diabetes, and hypertension. Moreover, cancer cells can activate a resting endothelium by secreting pro-angiogenic factors, in order to promote neoangiogenesis, which is essential for tumor growth. Endothelial altered phenotype is mirrored by altered mRNA, microRNA, and protein expression, with a microRNA being able to control pathways by regulating the expression of multiple mRNAs. In this review we will consider the involvement of microRNAs in modulating the response of endothelial cells to metabolic stresses and their role in promoting or halting angiogenesis.

Geniposide inhibits high glucose-induced cell adhesion through the NF-kappaB signaling pathway in human umbilical vein endothelial cells

AIM

To investigate whether geniposide, an iridoid glucoside extracted from gardenia jasminoides ellis fruits, inhibits cell adhesion to human umbilical vein endothelial cells (HUVECs) induced by high glucose and its underlying mechanisms.

METHODS

HUVECs were isolated from human umbilical cords and cultured. The adhesion of monocytes to HUVECs was determined using fluorescence-labeled monocytes. The mRNA and protein levels of vascular cell adhesion molecule-1 (VCAM-1) and endothelial selectin (E-selectin) were measured using real-time RT-PCR and ELISA. Reactive oxygen species (ROS) production was measured using a fluorescent probe. The amounts of nuclear factor-kappa B (NF-kappaB) and inhibitory factor of NF-kappaB (IkappaB) were determined using Western blot analysis. The translocation of NF-kappaB from the cytoplasm to the nucleus was determined using immunofluorescence.

RESULTS

Geniposide (10-20 mumol/L) inhibited high glucose (33 mmol/L)-induced adhesion of monocytes to HUVECs in a dose-dependent manner. This compound (5-40 mumol/L) also inhibited high glucose-induced expression of VCAM-1 and E-selectin at the gene and protein levels. Furthermore, geniposide (5-20 micromol/L) decreased ROS production and prevented IkappaB degradation in the cytoplasm and NF-kappaB translocation from the cytoplasm to the nucleus in HUVECs.

CONCLUSION

Geniposide inhibits the adhesion of monocytes to HUVECs and the expression of CAMs induced by high glucose, suggesting that the compound may represent a new treatment for diabetic vascular injury. The mechanism underlying this inhibitory effect may be related to the inhibition of ROS overproduction and NF-kappaB signaling pathway activation by geniposide.

The global diabetes epidemic as a consequence of lifestyle-induced low-grade inflammation

The recent major increase in the global incidence of type 2 diabetes suggests that most cases of this disease are caused by changes in environment and lifestyle. All major risk factors for type 2 diabetes (overnutrition, low dietary fibre, sedentary lifestyle, sleep deprivation and depression) have been found to induce local or systemic low-grade inflammation that is usually transient or milder in individuals not at risk for type 2 diabetes. By contrast, inflammatory responses to lifestyle factors are more pronounced and prolonged in individuals at risk of type 2 diabetes and appear to occur also in the pancreatic islets. Chronic low-grade inflammation will eventually lead to overt diabetes if counter-regulatory circuits to inflammation and metabolic stress are compromised because of a genetic and/or epigenetic predisposition. Hence, it is not the lifestyle change per se but a deficient counter-regulatory response in predisposed individuals which is crucial to disease pathogenesis. Novel approaches of intervention may target these deficient defence mechanisms.

Antioxidants attenuate hyperglycaemia-mediated brain endothelial cell dysfunction and blood-brain barrier hyperpermeability

AIMS

Hyperglycaemia (HG), in stroke patients, is associated with worse neurological outcome by compromising endothelial cell function and the blood-brain barrier (BBB) integrity. We have studied the contribution of HG-mediated generation of oxidative stress to these pathologies and examined whether antioxidants as well as normalization of glucose levels following hyperglycaemic insult reverse these phenomena.

METHODS

Human brain microvascular endothelial cell (HBMEC) and human astrocyte co-cultures were used to simulate the human BBB. The integrity of the BBB was measured by transendothelial electrical resistance using STX electrodes and an EVOM resistance meter, while enzyme activities were measured by specific spectrophotometric assays.

RESULTS

After 5 days of hyperglycaemic insult, there was a significant increase in BBB permeability that was reversed by glucose normalization. Co-treatment of cells with HG and a number of antioxidants including vitamin C, free radical scavengers and antioxidant enzymes including catalase and superoxide dismutase mimetics attenuated the detrimental effects of HG. Inhibition of p38 mitogen-activated protein kinase (p38MAPK) and protein kinase C but not phosphoinositide 3 kinase (PI3 kinase) also reversed HG-induced BBB hyperpermeability. In HBMEC, HG enhanced pro-oxidant (NAD(P)H oxidase) enzyme activity and expression that were normalized by reverting to normoglycaemia.

CONCLUSIONS

HG impairs brain microvascular endothelial function through involvements of oxidative stress and several signal transduction pathways.

Nitric oxide attenuates vascular endothelial cadherin-mediated vascular integrity in human chronic inflammation

In this study, we examined the role of nitric oxide (NO) in controlling vascular integrity mediated by vascular endothelial (VE)-cadherin in chronic inflammation. Periapical granulomas were analysed for the expression of inducible NO synthase (iNOS) and VE-cadherin, and more iNOS expression than VE-cadherin was shown. Human umbilical vein endothelial cells (HUVECs) were stimulated with proinflammatory cytokines and lipopolysaccharide extracted from Porphyromonas gingivalis and it induced iNOS expression, whereas it reduced VE-cadherin expression, compared with negative controls. On the other hand, pre-incubation with 1400W, an iNOS-specific inhibitor, markedly reduced iNOS expression in stimulated HUVECs and restored VE-cadherin expression to its control level, suggesting that vascular integrity was modulated in conjunction with the reduction of NO. Immunocytochemistry confirmed the functional role of NO in cultured HUVEC monolayers with or without 1400W. These data are consistent with a hypothesis suggesting that NO could attenuate VE-cadherin-mediated vascular integrity in human chronic inflammation.

Inhibition of monocyte chemoattractant protein-1 by Krüppel-like factor 5 small interfering RNA in the tumor necrosis factor- alpha-activated human umbilical vein endothelial cells

Krüppel-like factor 5 (KLF5) is one of the pivotal transcriptional factors communicating with inflammatory cytokines. Regulation of monocyte chemoattractant protein-1 (MCP-1) is a target to prevent from inflammation and atherogenic changes in patient with diabetes mellitus. This study was made to determine whether KLF5 may associate with MCP-1 expression in human umbilical vein endothelial cells (HUVECs) induced by tumor necrosis factor-alpha (TNF-alpha), in terms of the initial events of damaged vascular cells in diabetes. MCP-1 expression was markedly augmented by the treatment of TNF-alpha to HUVECs, but this augmentation was inhibited by KLF5 small interfering RNA, which primarily suppressed the expression of KLF5 at mRNA levels in the cells. Though TNF-alpha augmented the levels of endothelin-1 (ET-1) and attenuated those of embryonic form of myosin heavy chain (SMemb) in HUVECs, the inhibition of KLF5 did not affect the levels of these cytokines in the cells. These results suggested that in HUVECs, KLF5 is playing a critical role in regulating the expression of MCP-1, which has been considered to be involved in the diabetic atherogenic events.

Felodipine attenuates vascular inflammation in a fructose-induced rat model of metabolic syndrome via the inhibition of NF-kappaB activation

AIM

Metabolic syndrome is associated with an increased incidence of atherosclerosis. Clinical studies have shown that calcium channel blockers (CCB) inhibit the progression of atherosclerosis. However, the underlying mechanism is unclear. We investigated the inhibitory effect of felodipine on adhesion molecular expression and macrophage infiltration in the aorta of high fructose-fed rats (FFR).

METHODS

Male Wistar rats were given 10% fructose in drinking water. After 32 weeks of high fructose feeding, they were treated with felodipine (5 mg x kg(-1) x d(-1)) for 6 weeks. The control rats were given a normal diet and water. The aortic expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) and the infiltration of macrophages were measured by real-time RT-PCR and/or immunohistochemistry. NF-kappaB activity was measured by electrophoretic mobility shift assay (EMSA).

RESULTS

After 32 weeks of high fructose feeding, FFR displayed increased body weight, systolic blood pressure (SBP), serum insulin, and triglycerides when compared with the control rats. The aortic expressions of ICAM-1 and VCAM-1 were significantly increased in FFR than in the control rats and accompanied by the increased activity of NF-kappaB. FFR also showed significantly increased CD68- positive macrophages in the aortic wall. After treatment with felodipine, SBP, serum insulin, and the homeostasis model assessment decreased significantly. In addition to reducing ICAM-1 and VCAM-1, felodipine decreased macrophages in the aortic wall. EMSA revealed that felodipine inhibited NF-kappaB activation in FFR.

CONCLUSION

Felodipine inhibited vessel wall inflammation. The inhibition of NF-kappaB may be involved in the modulation of vascular inflammatory response by CCB in metabolic syndrome.

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.

Lycopus lucidus inhibits high glucose-induced vascular inflammation in human umbilical vein endothelial cells

Vascular inflammatory process has been suggested to play a key role in the initiation and progression of atherosclerosis, a major complication of diabetes mellitus. Lycopus lucidus Turcz. has been used as an oriental traditional medicine including Korea and its crude drug is known to have an anti-inflammatory effect. Thus we investigated whether the aqueous extract of the leaves of L. lucidus Turcz. (ALT) suppresses vascular inflammatory process induced by high glucose in primary cultured human umbilical vein endothelial cells (HUVEC). Western blot analysis revealed that incubation of HUVEC with high glucose increased cell adhesion molecules (CAMs) expression levels. However, high glucose-induced increase of CAMs expression was significantly attenuated by pretreatment with ALT in a dose-dependent manner. The enhanced cell adhesion between monocyte and HUVEC induced by high glucose was also blocked by pretreatment with ALT. High glucose-induced hydrogen peroxide production and DCF-sensitive intracellular reactive oxygen species (ROS) formation. Pretreatment with ALT inhibited high glucose-induced ROS formation. In addition, ALT suppressed the translocation and promoter transcriptional activity of NF-kappaB increased in high glucose condition. Taken together, the present data suggested that ALT could suppress high glucose-induced vascular inflammatory process, which may be closely related with the inhibition of ROS and NF-kappaB activation in HUVEC.