Development Of Diabetic Vascular Complications Research Articles

Homoplantaginin attenuates high glucose-induced vascular endothelial cell apoptosis through promoting autophagy via the AMPK/TFEB pathway.

Vascular endothelial cell (VEC) injury is a key factor in the development of diabetic vascular complications. Homoplantaginin (Hom), one of the main flavonoids from Salvia plebeia R. Br. has been reported to protect VEC. However, its effects and mechanisms against diabetic vascular endothelium remain unclear. Here, the effect of Hom on VEC was assessed using high glucose (HG)-treated human umbilical vein endothelial cells and db/db mice. In vitro, Hom significantly inhibited apoptosis and promoted autophagosome formation and lysosomal function such as lysosomal membrane permeability and the expression of LAMP1 and cathepsin B. The antiapoptosis effect of Hom was reversed by autophagy inhibitor chloroquine phosphate or bafilomycin A1. Furthermore, Hom promoted gene expression and nuclear translocation of transcription factor EB (TFEB). TFEB gene knockdown attenuated the effect of Hom on upregulating lysosomal function and autophagy. Moreover, Hom activated adenosine monophosphate-dependent protein kinase (AMPK) and inhibited the phosphorylation of mTOR, p70S6K, and TFEB. These effects were attenuated by AMPK inhibitor Compound C. Molecular docking showed a good interaction between Hom and AMPK protein. Animal studies indicated that Hom effectively upregulated the protein expression of p-AMPK and TFEB, enhanced autophagy, reduced apoptosis, and alleviated vascular injury. These findings revealed that Hom ameliorated HG-mediated VEC apoptosis by enhancing autophagy via the AMPK/mTORC1/TFEB pathway.

R-spondin 3 Inhibits High Glucose-Induced Endothelial Activation Through Leucine-Rich G Protein-Coupled Receptor 4/Wnt/β-catenin Pathway.

High glucose-induced endothelial activation plays critical roles in the development of diabetic vascular complications. R-spondin 3 could inhibit inflammatory damage, and diabetic vascular inflammation is secondary to endothelial activation. In this article, we identify R-spondin 3 as a novel regulator of high glucose-induced endothelial activation. We found that the serum levels of R-spondin 3 were significantly reduced in type 2 diabetic patients and db/db mice. We observed that the increased expressions of vascular cell adhesion molecule-1, intercellular cell adhesion molecule-1, and monocyte chemoattractant protein-1 (endothelial activation makers) in high glucose-stimulated human umbilical vein endothelial cell lines (HUVECs) could be inhibited by overexpressing R-spondin 3 or human R-spondin 3 recombinant protein. Subsequently, high glucose-induced adhesion and migration of human myeloid leukemia mononuclear cells (THP-1 cells) to HUVECs were markedly suppressed by the overexpression of R-spondin 3 in HUVECs. Moreover, the inhibitory effect of R-spondin 3 on the expressions of vascular cell adhesion molecule-1, intercellular cell adhesion molecule-1, and monocyte chemoattractant protein-1 in high glucose-treated HUVECs could be blocked by knockdown of leucine-rich G protein-coupled receptor 4 (R-spondin 3 receptor) or the specific inhibitor of Wnt/β-catenin pathway. Taken together, R-spondin 3 could suppress high glucose-induced endothelial activation through leucine-rich G protein-coupled receptor 4/Wnt/β-catenin pathway.

Skin autofluorescence corresponds to microvascular reactivity in diabetes mellitus

Advanced glycation accelerated by chronic hyperglycaemia contributes to the development of diabetic vascular complications throughout several mechanisms. One of these mechanisms is supposed to be impaired microvascular reactivity, that precedes significant vascular changes. The aim of this study was to find an association between advanced glycation, the soluble receptor for AGEs (sRAGE), and microvascular reactivity (MVR) in diabetes.Skin autofluorescence (SAF), which reflects advanced glycation, was assessed by AGE-Reader, MVR was measured by laser Doppler fluxmetry and evaluated together with sRAGE in 43 patients with diabetes (25 Type 1 and 18 Type 2) and 26 healthy controls of comparable age.SAF was significantly higher in patients with diabetes compared to controls (2.4 ± 0.5 vs. 2.0 ± 0.5 AU; p < 0.01). Patients with diabetes with SAF > 2.3 AU presented significantly worse MVR in both post-occlusive reactive hyperaemia (PORH) on the finger and forearm, and thermal hyperaemia (TH), compared to patients with SAF < 2.3 AU. SAF was age dependent in both diabetes (r = 0.41, p < 0.01) and controls (r = 0.45, p < 0.05). There was no association between SAF and diabetes control expressed by glycated haemoglobin. A significant relationship was observed between SAF and sRAGE in diabetes (r = 0.56, p < 0.001), but not in controls. A significant inverse association was found between SAF and MVR on the forearm in diabetes (PORH: r = −0.42, p < 0.01; TH: r = −0.46, p < 0.005).Both advanced glycation expressed by higher SAF or sRAGE and impaired MVR are involved in the pathogenesis of vascular complications in diabetes, and we confirm a strong interplay of these processes in this scenario.

IDF21-0162 Hexokinase-2 linked glycolytic overload – key initiating driver of the development of diabetic vascular complications

Background: The hypothesis of multiple pathways of metabolic dysfunction in hyperglycemia of diabetes explains involvement of mitochondrial dysfunction, protein kinase c, hexosamine pathway and methylglyoxal (MG)-derived formation of advanced glycation endproducts in the cell biology of vascular complications of diabetes. It does not explain, however, how the increased glucose metabolism driving this dysfunction occurs at sites of vascular complications when the hexokinase isozymes therein, hexokinase-1 (HK1) and hexokinase-2 (HK2), are saturated with glucose in normoglycemia and there is no increase of hexokinase expression in hyperglycemia. This conundrum was recently resolved when it was found that high cellular glucose concentration stabilizes HK2 to proteolysis, increasing HK2 protein and activity. This sends a wave of increased glycolytic intermediates through early-stage glycolysis driving metabolic dysfunction. Increased HK2 may be corrected by glyoxalase 1 inducer, trans-resveratrol and hesperetin in combination (tRES-HESP). HK2-linked glycolytic overload is the initiator of metabolic dysfunction in hyperglycemia and tRES-HESP may offer an exciting new route to treatment of diabetic complications. Aim: The aim of this study is to assess the evidence for HK2-linked glycolytic overload in human aortal endothelial cells (HAECs) and renal proximal tubular epithelial cells (PTECs) in model hyperglycemia in vitro and explore literature evidence for HK2-linked glycolytic overload sites of vascular complications in vivo. Method: HAECs and PTECs were cultured according to the supplier’s instructions in 4.1 - 20 mM glucose and 7 – 25 mM glucose respectively for 6 - 72 h. HK2 protein abundance was assessed by Western blotting, normalized to β-actin; and glucose consumption and flux of formation of MG (assessed by accumulation of D-lactate) were determined by assay of glucose and D-lactate at the start and end of cultures, normalizing flux to cell number. Results: HK2 protein increased progressively with time and increasing glucose concentration in HAEC and PTEC cultures. In HAECs, HK2 abundance was increased maximally by 37% whereas total glucose consumption was increased by 59% (6.77 ± 0.12 to 10.75 ± 0.21 µmol/day/million cells; P<0.001, n = 3). HK2 abundance increased from 4.1 mM to 20 mM glucose, increasing ca. 2.4% per mM glucose. HK2 abundance correlated positively with initial glucose concentration and flux of glucose consumption (r = 0.96 and r = 0.85, respectively; P<0.001; n = 12, Pearson) and metabolic dysfunction – as judged by increased flux of MG formation (r = 0.93; P<0.001, n = 12); HK1 abundance did not. tRES-HESP prevented increased HK2 abundance, increased glucose consumption and metabolic dysfunction of HAECs in high glucose concentration. Discussion: We conclude that HK2 abundance increases with increased glucose concentration in the clinical range in diabetes in HAECs and PTECs, producing glycolytic overload and metabolic dysfunction in high glucose concentration. Criteria for HK2-linked glycolytic overload – GLUT1 and/or GLUT3 glucose uptake and expression of HK2 - are found at sites of diabetic vascular complications clinically; and a biomarker of its occurrence - increased glycogen deposition - is found with development of complications. tRES-HESP offers a prospective new approach to prevent the development of vascular complication of diabetes.

Dopamine 1 receptors inhibit apoptosis via activating CSE/H2 S pathway in high glucose-induced vascular endothelial cells.

High glucose (HG)-induced dysfunction of vascular endothelial cells plays a crucial role in the development of diabetic vascular complications. Inhibition of cystathionine γ-synthase/hydrogen sulfide (CSE/H2 S) pathway is one of the causes of vascular endothelial cellinjury induced by HG. Dopamine D1 receptors (DR1) are widely expressed and regulate important physiological functions in the vascular system. However, the effect of DR1 inhibition on HG-induced vascular endothelial apoptosis by regulating the CSE/H2 S pathway is unclear. Therefore, we aimed to determine if DR1 can regulate the CSE/H2 S pathway and regulate the effect of DR1 on HG-induced apoptosis in human umbilical vein endothelial cells. In this study, we found that HG treatment significantly decreased the expression of DR1 and CSE and the endogenous content of H2 S;DR1 agonist SKF 38393 reversed these effects, while sodium hydrosulfide(NaHS) only increased CSE expression and the endogenous H2 S production and had no effect on DR1 expression. Meanwhile, HG significantly increasedthe intracellular calcium concentration ([Ca2+ ]i ),and SKF 38393 further increased HG-induced [Ca2+ ]i . In addition, HG increased the lactate dehydrogenase activity, malondialdehyde and reactive oxygen species contents, apoptotic rate, the expression of cleaved caspase-3, caspase-9, and cytochrome c, and the activity of phosphorylated-inhibitor of nuclear factor-kappaBα (NF-κBα) (p-IκBα) and phosphorylated-NF-κB (p-NF-κB), and reduced cell viability, superoxide dismutase activity, and Bcl-2 expressions. SKF 38393 and NaHS markedly reversed the effect of HG. The effect of SKF 38393 was similar to N-acetyl- l-cysteine (an inhibitor of oxidative stress) or pyrrolidinedithiocarbamate ammonium (an NF-kB inhibitor). Taken together, DR1 upregulates the CSE/H2 S pathway by increasing the [Ca2+ ]i , which inhibits HG-induced apoptosis via downregulating NF-κB/IκBα pathway in vascular endothelial cells.

Hexokinase-2-Linked Glycolytic Overload and Unscheduled Glycolysis-Driver of Insulin Resistance and Development of Vascular Complications of Diabetes.

The recent discovery of the glucose-induced stabilization of hexokinase-2 (HK2) to proteolysis in cell dysfunction in model hyperglycemia has revealed a likely key initiating factor contributing to the development of insulin resistance and vascular complications in diabetes. Consequently, the increased flux of glucose metabolism without a change in the expression and activity of glycolytic enzymes produces a wave of increased glycolytic intermediates driving mitochondrial dysfunction and increased reactive oxygen species (ROS) formation, the activation of hexosamine and protein kinase C pathways, the increased formation of methylglyoxal-producing dicarbonyl stress, and the activation of the unfolded protein response. This is called HK2-linked glycolytic overload and unscheduled glycolysis. The conditions required to sustain this are GLUT1 and/or GLUT3 glucose uptake and the expression of HK2. A metabolic biomarker of its occurrence is the abnormally increased deposition of glycogen, which is produced by metabolic channeling when HK2 becomes detached from mitochondria. These conditions and metabolic consequences are found in the vasculature, kidneys, retina, peripheral nerves, and early-stage embryo development in diabetes and likely sustain the development of diabetic vascular complications and embryopathy. In insulin resistance, HK2-linked unscheduled glycolysis may also be established in skeletal muscle and adipose tissue. This may explain the increased glucose disposal by skeletal uptake in the fasting phase in patients with type 2 diabetes mellitus, compared to healthy controls, and the presence of insulin resistance in patients with type 1 diabetes mellitus. Importantly, glyoxalase 1 inducer—trans-resveratrol and hesperetin in combination (tRES-HESP)—corrected HK2-linked glycolytic overload and unscheduled glycolysis and reversed insulin resistance and improved vascular inflammation in overweight and obese subjects in clinical trial. Further studies are now required to evaluate tRES-HESP for the prevention and reversal of early-stage type 2 diabetes and for the treatment of the vascular complications of diabetes.

Regulation of Oxidative Stress by Long Non-Coding RNAs in Vascular Complications of Diabetes.

Diabetes mellitus is a well-known metabolic disorder with numerous complications, such as macrovascular diseases (e.g., coronary heart disease, diabetic cardiomyopathy, stroke, and peripheral vascular disease), microvascular diseases (e.g., diabetic nephropathy, retinopathy, and diabetic cataract), and neuropathy. Multiple contributing factors are implicated in these complications, and the accumulation of oxidative stress is one of the critical ones. Several lines of evidence have suggested that oxidative stress may induce epigenetic modifications that eventually contribute to diabetic vascular complications. As one kind of epigenetic regulator involved in various disorders, non-coding RNAs have received great attention over the past few years. Non-coding RNAs can be roughly divided into short (such as microRNAs; ~21–25 nucleotides) or long non-coding RNAs (lncRNAs; >200 nucleotides). In this review, we briefly discussed the research regarding the roles of various lncRNAs, such as MALAT1, MEG3, GAS5, SNHG16, CASC2, HOTAIR, in the development of diabetic vascular complications in response to the stimulation of oxidative stress.

Large-leaf yellow tea attenuates high glucose-induced vascular endothelial cell injury by up-regulating autophagy and down-regulating oxidative stress.

Vascular endothelial cell injury induced by high glucose (HG) plays an important role in the occurrence and development of diabetic vascular complications. Yellow tea has a protective effect on vascular endothelial cells. However, the molecular mechanisms underlying this effect are unclear. In this study, the effects of the n-butanol fraction of Huoshan large-leaf yellow tea extract (HLYTBE) on vascular endothelial injury were investigated using human umbilical vein endothelial cells (HUVECs) and diabetic mice. In HUVECs, HLYTBE significantly reduced the production of reactive oxygen species, increased the activity of anti-oxidases (superoxide dismutase and glutathione peroxidase), enhanced the production of reduced glutathione, and decreased the level of oxidized glutathione, thereby improving cell viability. HLYTBE also promoted autophagosome formation, increased the LC3-II/LC3-I ratio, increased the expressions of Beclin1 and Atg 5, and decreased the expression of p62. HLYTBE up-regulated p-AMPK and down regulated p-mTOR, and these effects were reversed by compound C, an AMPK inhibitor. HLYTBE reduced apoptosis and cytochrome C expression, and these effects were attenuated by the autophagy inhibitor 3-methyladenine. In vivo studies showed that HLYTBE improved the impaired pyruvate tolerance, glucose tolerance, and insulin resistance; reduced the concentrations of blood glucose, glycated serum protein, lipids, and 8-isomeric prostaglandin 2α; increased the anti-oxidase activity in serum; and alleviated pathological damage in the thoracic aorta of diabetic mice induced by high sucrose-high fat diet along with streptozotocin. The results suggest that HLYTBE protects the vascular endothelium by up-regulating autophagy via the AMPK/mTOR pathway and inhibiting oxidative stress.

384-P: Text Mining and Bioinformatic Identification of Genes Linking Glycemic Variability and Impaired Angiogenesis in Diabetes

The Aim: to identify key genes involved in angiogenic response and influenced by enhanced glycemic variability (GV) in diabetes. Methods: Text-mining of Medline/Pubmed abstracts, reconstruction and analysis of gene networks related to GV and angiogenesis was performed by ANDSystem (www-bionet.sscc.ru/and/cell/). Genes associated with both hyperglycemia and hypoglycemia were attributed to be GV-related. Compounds targeting the identified genes were found using the TTD database (db.idrblab.net/ttd/). Results: The set of genes implicated in angiogenesis that are up- or down-regulated by both hyperglycemia and hyperglycemia and compounds targeting and regulating these genes are summarized in the Table. Conclusions: The obtained results support the hypothesis that detrimental effect of enhanced GV in diabetes could be realized by up- or down-regulation of the genes involved in angiogenic response. The role of the identified genes and compounds influencing their activity in the development of diabetic vascular complications requires experimental testing. Disclosure O. V. Saik: None. V. Klimontov: Advisory Panel; Self; Boehringer Ingelheim International GmbH, Sanofi, Research Support; Self; Boehringer Ingelheim International GmbH, Speaker’s Bureau; Self; AstraZeneca, Medtronic. Funding Russian Science Foundation (20-15-00057)

Coronary Flow Reserve and Glycemic Variability in Patients with Coronary Artery Disease.

Objective Glycemic variability is being increasingly recognized as an early indicator of glucose metabolic disorder and may contribute to the development of diabetic vascular complications, such as coronary microvascular dysfunction. The present study sought to investigate the relationship between coronary microvascular function assessed by intracoronary thermodilution method and glycemic variability on a continuous glucose monitoring system (CGMS). Methods We prospectively enrolled 40 patients with or without known diabetes mellitus who had epicardial coronary artery disease referred for coronary angiography and were not treated with diabetic medications. Of these, two had a significant stenosis in the left main coronary artery and were therefore excluded from the analyses. In the end, 38 patients were equipped with a CGMS and underwent intracoronary physiological assessments in the unobstructed left anterior descending artery. The mean amplitude of glycemic excursion (MAGE) and standard deviation were calculated from the obtained CGMS data as indicators of glucose variability. Results Coronary flow reserve (CFR) was negatively correlated with MAGE (r=-0.328, p=0.044) and standard deviation (r=-0.339, p=0.037) on CGMS, while the index of microcirculatory resistance showed no such correlation. Multivariable linear regression analyses showed that MAGE on CGMS was significantly associated with CFR after adjusting for age, sex, fractional flow reserve and hemoglobin A1c. Conclusion Higher MAGE on CGMS was associated with reduced CFR in stable patients with coronary artery disease, suggesting a potential effect of glycemic variability on coronary microvascular flow regulation. A further study with a larger sample size needs to be conducted to confirm our findings.

Role of Exosomal Intercellular Communications in Diabetic Vascular Complications in Experimental Animals

Background: Cardiovascular complications are the main cause of death in diabetic patients. Intercellular communications may link diabetes to the cardiovascular complications. Exosomes are now emerging as a key mediator of intercellular communications. Aim: This study aimed to study the possible role of intercellular communications between adipose derived stem cells (ASCs) and vascular smooth muscle cells (VSMCs) in the development of diabetic vascular complications. Methods: To create an in vitro model which can mimic diabetic conditions, primary mouse ASCs from mouse aortic perivascular adipose tissue (PVAT) were treated with a cocktail of LPS, high glucose and Palmitate. ASCs conditioned medium were collected, and exosomes were isolated. Migratory capacity of vascular smooth muscle cells (VSMCs) incubated with ASCs derived exosomes were assessed via scratch assay. Results: Exosomes derived from our in vitro model of ASCs promoted migration of VSMCs. Conclusion: These data suggest an association between diabetes and progression of vascular dysfunction via intercellular communications mediated by exosomes derived from perivascular adipose tissue.

Co Q10 improves vascular reactivity in male diabetic rats by enhancing insulin sensitivity and antioxidant effect

Oxidative stress is the main player in the development of diabetic vascular complications. Co-Q10 is a natural antioxidant present in the body and in many foods. This study was designed to evaluate the effect of Co-Q10 administration to improve vascular complications and increase insulin sensitivity in diabetic rats. Fifty male rats were divided into five groups: control, diabetic untreated, diabetic insulin-treated, diabetic Co-Q10-treated, and diabetic combined-treated groups. After 8 weeks, blood pressure and vascular reactivity to NE and ACh, fasting glucose, insulin, C-peptide, MDA, TAC, HbA1c, and the HOMA-IR were measured. Diabetes increased fasting glucose, HbA1c, HOMA-IR, MDA, blood pressure, and decreased TAC and vascular reactivity. Ttreatment with insulin or Co-Q10 improved glycemic parameters and increasing antioxidant levels compared to diabetic group. Combined Co-Q10 with insulin was found to increase insulin sensitivity and decrease its resistance, which helps to decrease insulin doses in diabetic patients and reduce its side effects.

Glycolaldehyde-modified proteins cause adverse functional and structural aortic remodeling leading to cardiac pressure overload

Growing evidence supports the role of advanced glycation end products (AGEs) in the development of diabetic vascular complications and cardiovascular diseases (CVDs). We have shown that high-molecular-weight AGEs (HMW-AGEs), present in our Western diet, impair cardiac function. Whether HMW-AGEs affect vascular function remains unknown. In this study, we aimed to investigate the impact of chronic HMW-AGEs exposure on vascular function and structure. Adult male Sprague Dawley rats were daily injected with HMW-AGEs or control solution for 6 weeks. HMW-AGEs animals showed intracardiac pressure overload, characterized by increased systolic and mean pressures. The contraction response to PE was increased in aortic rings from the HMW-AGEs group. Relaxation in response to ACh, but not SNP, was impaired by HMW-AGEs. This was associated with reduced plasma cyclic GMP levels. SOD restored ACh-induced relaxation of HMW-AGEs animals to control levels, accompanied by a reduced half-maximal effective dose (EC50). Finally, collagen deposition and intima-media thickness of the aortic vessel wall were increased with HMW-AGEs. Our data demonstrate that chronic HMW-AGEs exposure causes adverse vascular remodelling. This is characterised by disturbed vasomotor function due to increased oxidative stress and structural changes in the aorta, suggesting an important contribution of HMW-AGEs in the development of CVDs.

717-P: The Levels and Related Factors of Advanced Glycation End Products in Korean Patients with Type 2 Diabetes Mellitus

Advanced glycation end-products (AGEs) are known to be produced by the Maillard reaction, ingested through food. AGEs are actively generated and accumulated in the circulating blood and various tissues in diabetes mellitus patients by chronic hyperglycemia. AGEs play an important role in the development of diabetic vascular complications. The aim of this study was to assess levels and related factors of AGEs in Korean patients with type 2 diabetes mellitus. A total of 310 Korean men (n=177) and women (n=133) with T2DM subjects were participated. This study was measured and analyzed anthrometric data, body composition, and biochemical parameters. Tissue accumulated AGEs can be evaluated a non-invasive methodology by skin autofluorescence reader. The means age of total subjects was 58.9 ± 11.0 years, BMI was 25.8 ± 4.5 kg/m2. There is no difference between male and female patients in levels of AGEs, pulse wave velocity (PWV) and vein age. There is a significant correlation among AGEs, height, weight, body mass index, skeletal muscle mass, diastolic blood pressure and HDL cholesterol for male patients and among fasting blood sugar, glycated hemoglobin A1c, total cholesterol, LDL cholesterol, and systolic blood pressure for female patients. The correlation of AGEs for both male and female subjects is highly associated with age, duration of diabetes and PWV. This study shows possibility of using AGEs as an index for clinical diagnosis, complications prediction, and diabetes management in Korean patients with type 2 diabetes mellitus. However, it is considered that a change in AGEs may be influenced by gender, age, and duration of diabetes. Disclosure J. Yim: None. Y. Kim: None. J. Park: None.

Omentin-1 protects against high glucose-induced endothelial dysfunction via the AMPK/PPARδ signaling pathway

High glucose-induced endothelial dysfunction is a critical initiating factor in the development of diabetic vascular complications. Omentin-1 has been regarded as a novel biomarker of endothelial function in subjects with type-2 diabetes (T2D); however, it is unclear whether omentin-1 has any direct effect in ameliorating high glucose-induced endothelial dysfunction. In the present study, we analyzed the effect of omentin-1 on high glucose-induced endothelial dysfunction in isolated mouse aortas and mouse aortic endothelial cells (MAECs). Vascular reactivity in aortas was measured using wire myography. The expression levels of AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor δ (PPARδ), Akt, endothelial nitric-oxide synthase (eNOS), and endoplasmic reticulum (ER)-stress markers in MAECs were determined by Western blotting. The production of reactive oxygen species (ROS) and nitric oxide (NO) was assessed by diluted fluoroprobe, 2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA) and 4-amino-5-methylamino-2′,7′-difluorofluorescein (DAF-FM DA), respectively. We found that ex vivo treatment with omentin-1 reversed impaired endothelial-dependent relaxations (EDR) in mouse aortas after high-glucose insult. Elevated ER-stress markers, oxidative stress, and reduction of NO production induced by high glucose in MAECs were reversed by omentin-1 treatment. Omentin-1 also effectively reversed tunicamycin-induced ER stress responses in MAECs, as well as ameliorated impairment of endothelial-dependent relaxation in mouse aortas. Moreover, omentin-1 increased AMPK phosphorylation with a subsequent increase in PPARδ expression, while also restoring the decreased phosphorylation of Akt and eNOS. The effects of omentin-1 were abolished by cotreatment of compound C (AMPK inhibitor) and GSK0660 (PPARδ antagonist). These data indicate that omentin-1 protects against high glucose-induced vascular-endothelial dysfunction through inhibiting ER stress and oxidative stress and increasing NO production via activation of AMPK/PPARδ pathway.

Liraglutide Inhibits Endothelial-to-Mesenchymal Transition and Attenuates Neointima Formation after Endovascular Injury in Streptozotocin-Induced Diabetic Mice.

Hyperglycaemia causes endothelial dysfunction, which is the initial process in the development of diabetic vascular complications. Upon injury, endothelial cells undergo an endothelial-to-mesenchymal transition (EndMT), lose their specific marker, and gain mesenchymal phenotypes. This study investigated the effect of liraglutide, a glucagon-like peptide 1 (GLP-1) receptor agonist, on EndMT inhibition and neointima formation in diabetic mice induced by streptozotocin. The diabetic mice with a wire-induced vascular injury in the right carotid artery were treated with or without liraglutide for four weeks. The degree of neointima formation and re-endothelialisation was evaluated by histological assessments. Endothelial fate tracing revealed that endothelium-derived cells contribute to neointima formation through EndMT in vivo. In the diabetic mouse model, liraglutide attenuated wire injury-induced neointima formation and accelerated re-endothelialisation. In vitro, a high glucose condition (30 mmol/L) triggered morphological changes and mesenchymal marker expression in human umbilical vein endothelial cells (HUVECs), which were attenuated by liraglutide or Activin receptor-like 5 (ALK5) inhibitor SB431542. The inhibition of AMP-activated protein kinase (AMPK) signaling by Compound C diminished the liraglutide-mediated inhibitory effect on EndMT. Collectively, liraglutide was found to attenuate neointima formation in diabetic mice partially through EndMT inhibition, extending the potential therapeutic role of liraglutide.

Chronic administration of nano-sized PAMAM dendrimers in vivo inhibits EGFR-ERK1/2-ROCK signaling pathway and attenuates diabetes-induced vascular remodeling and dysfunction

We investigated whether chronic administration of nano-sized polyamidoamine (PAMAM) dendrimers can have beneficial effects on diabetes-induced vascular dysfunction by inhibiting the epidermal growth factor receptor (EGFR)-ERK1/2-Rho kinase (ROCK)—a pathway known to be critical in the development of diabetic vascular complications. Daily administration of naked PAMAMs for up to 4 weeks to streptozotocin-induced diabetic male Wistar rats inhibited EGFR-ERK1/2-ROCK signaling and improved diabetes-induced vascular remodeling and dysfunction in a dose, generation (G6 > G5) and surface chemistry-dependent manner (cationic > anionic > neutral). PAMAMs, AG1478 (a selective EGFR inhibitor), or anti-EGFR siRNA also inhibited vascular EGFR-ERK1/2-ROCK signaling in vitro. These data showed that naked PAMAM dendrimers have the propensity to modulate key (e.g. EGFR) cell signaling cascades with associated pharmacological consequences in vivo that are dependent on their physicochemical properties. Thus, PAMAMs, alone or in combination with vasculoprotective agents, may have a beneficial role in the potential treatment of diabetes-induced vascular complications.

Relationship between different normal serum bilirubin concentrations and diabetic nephropathy in patients with type 2 diabetes mellitus

Background: One of the major complications of type 2 diabetes is diabetic nephropathy (DN). Nephropathy develops in ~20–40% of patients with diabetes and is the single leading cause of end-stage renal disease (ESRD) around the world.(1) Oxidative stress has been considered to be an important pathogenic factor in the development of diabetic vascular complications, including nephropathy. Bilirubin(BIL) has been recognized as an endogenous antioxidant. Objective: The objective of this study is to detect the relationship between serum bilirubin concentrations and diabetic nephropathy in patients with type 2 diabetes mellitus. PATIENTS & METHODS:The study included 92 patient with type 2 diabetes mellitus who visit Sohag University Hospital ,All patients in this study were subjected to full history taking, complete physical examination, and laboratory investigations including urine analysis, albumin creatinine ratio, renal and liver function tests. Patients with T2DM were recruited and bilirubin concentrations were compared between patients with or without diabetic nephropathy. DN was diagnosed according to KDOQI Clinical Practice Guidelines and Clinical Practice Recommendations for Diabetes and Chronic Kidney Disease .(7) Patients were classified according to stage of nephropathy(8): 1-stage 1 ------- albumin creatinine ratio less than 30 mg/g creatinin. 2-stage 2 ------- morphologic lesions without signs of clinical disease. 3-stage 3 ------- albumin creatinine ratio more than 30 , less than 300 mg/g creatinin. 4-stage 4 ------- albumin creatinine ratio more than 300 mg/g creatinin. 5- stage 5 ------- end stage renal disease. Results: Multiple stepwise regression analysis was used to examine the relationship between bilirubin concentrations (within normal range) and albumin creatinin ratio. Conclusions Serum bilirubin concentration correlated negatively with stage of diabetic nephropathy, which suggests that bilirubin has a potential role for protection of diabetic nephropathy.

SOCS1-targeted therapy ameliorates renal and vascular oxidative stress in diabetes via STAT1 and PI3K inhibition

Oxidative stress resulting from excessive production of reactive oxygen species (ROS) or impaired antioxidant defenses is closely related to the development of diabetic vascular complications, including nephropathy and atherosclerosis. Chronic activation of Janus kinase/Signal transducer and activator of transcription (JAK/STAT) signaling pathway contributes to diabetic complications by inducing expression of genes involved in cell proliferation, fibrosis, inflammation, and oxidative stress. Suppressors of cytokine signaling (SOCS) family of endogenous JAK/STAT regulators is an attractive target for therapeutic intervention. We investigated the beneficial effect of two different SOCS1-targeted therapies (adenovirus-mediated gene transfer and kinase-inhibitory region peptidomimetic) to combat oxidative stress injury in an experimental diabetes model of concomitant renal and macrovascular disease (streptozotocin-induced diabetic apolipoprotein E-deficient mouse). Diabetes resulted in progressive alteration of redox balance in mice, as demonstrated by increased ROS levels and decreased antioxidant activity, which ultimately led to renal dysfunction and vascular injury. The molecular and pathological alterations in early diabetes were partially reversed by preventive intervention with SOCS1-targeted therapies. Importantly, SOCS1 peptidomimetic provided reno- and atheroprotection in diabetic mice even in a setting of established disease. Compared with untreated controls, kidney and aorta from SOCS1-treated mice exhibited significantly lower levels of superoxide anion, DNA oxidation marker and NADPH oxidase (Nox) subunits, along with higher expression of antioxidant enzymes. These trends correlated with a reduction in parameters of renal damage (albuminuria, creatinine and tubular injury), atherosclerosis (lesion size) and inflammation (leukocytes and chemokines). Mechanistic studies in renal, vascular and phagocytic cells exposed to cytokines and high-glucose showed that SOCS1 blocked ROS generation by inhibiting both Nox complex assembly and Nox subunit expression, an effect mediated by inactivation of JAK2, STAT1, and PI3K signaling pathways. This study provides evidence for SOCS1-targeted therapies, especially SOCS1 peptidomimetic, as an alternative antioxidant strategy to limit the progression of diabetic micro- and macrovascular complications.The authors investigated the effect of therapies based on the JAK/STAT regulator SOCS1 to combat diabetes-induced oxidative stress. The SOCS1 gene and peptidomimetic administration prevents renal damage and atherosclerosis in streptozotocin-diabetic mice by reducing oxidative stress and enhancing antioxidant genes. Mechanistically, SOCS1 prevents activation/expression of NADPH oxidase via PI3K and STAT1 inhibition.

Diabetes-Induced Vascular Dysfunction Can Be Attenuated with a Naked G7 Polyamidoamine Dendrimer In Vivo

Upregulation of epidermal growth factor receptor (EGFR) signaling is involved in development of diabetes-induced vascular dysfunction. Polyamidoamine (PAMAM) dendrimers (branch-like polymers) might be novel inhibitors of EGFR for they inhibit EGFR phosphorylation in vitro. Here, we investigated whether chronic administration of a generation (G) 7 PAMAM dendrimer could have beneficial effects on diabetes-induced vascular dysfunction by inhibiting EGFR signaling in a model of type 1 diabetes. Dendrimer administration (daily i.p for up to 4 weeks) to Male Wistar rats bearing streptozotocin-induced diabetes dose- and time-dependently inhibited EGFR-ERK1/2-ROCK signaling- a key pathway in the development of diabetic vascular complications. Dendrimer-induced inhibition of EGFR signaling correlated well with a significant correction in hyper-responsiveness of the diabetic mesenteric vascular bed to norephinephrine- a routinely used experimental measure of vascular dysfunction. The dendrimer also inhibited high glucose-induced EGFR-ERK1/2-ROCK signaling in primary vascular smooth muscle cells grown in high (25mM) glucose. These data show for the first time that a PAMAM dendrimer administered chronically in vivo can lead to inhibition of EGFR-ERK1/2-ROCK signaling and attenuate diabetes-induced vascular dysfunction in an experimental model of diabetes. Disclosure S. Akhtar: None. B. Chandrasekhar: None. A.Z. El-Hashim: None. I. Benter: None.