Endothelial Dysfunction In Diabetes Research Articles

The Impact of Punica granatum Linn and Its Derivatives on Oxidative Stress, Inflammation, and Endothelial Function in Diabetes Mellitus: Evidence from Preclinical and Clinical Studies.

Diabetes mellitus is recognized as the leading contributor to cardiovascular disease and associated mortality rates worldwide. Despite the use of pharmaceutical drugs to treat diabetes, its prevalence continues to rise alarmingly. Therefore, exploring remedies with a lower toxicity profile is crucial while remaining safe and effective in addressing this global public health crisis. Punica granatum Linn (pomegranate), known for its properties and safety profile, has been investigated in applied research and preclinical and clinical trials. However, conflicting reports still exist regarding its effects in diabetes. According to our knowledge, no systematic review has been conducted to critically analyze evidence from preclinical and clinical trials simultaneously, explicitly focusing on oxidative stress, inflammation, and endothelial function in diabetes. Therefore, in this systematic review, we searched for evidence on the impact of pomegranate in diabetes using databases such as PubMed, Scopus, and Google Scholar. Our inclusion criteria were limited to studies published in English. Of the 170 retrieved studies, 46 were deemed relevant and underwent critical analysis. The analyzed evidence suggests that pomegranate has the potential to alleviate oxidative stress, inflammation, and endothelial dysfunction in diabetes. Although a beneficial impact was noted in these markers, the endothelial function evidence still requires validation through further clinical trials with a powered sample size.

Ginsenoside Rg1 attenuates diabetic vascular endothelial dysfunction by inhibiting the calpain-1/ROS/PKC-β axis

AimsVascular endothelial dysfunction (VED) is the onset event of cardiovascular complications in type 2 diabetes mellitus. Ginsenoside Rg1 (Rg1) can improve the cardiovascular system, but its mechanism in diabetic vascular endothelial dysfunction has received little attention. Main methodsMale calpain-1-knockout and wild-type C57BL/6 J mice were intraperitoneally injected with streptozotocin and treated with Rg1 (10 and 20 mg/kg) for 8 weeks. Human aortic endothelial cells (HAECs) were incubated with high glucose (HG) and were pretreated with Rg1 (10, 20 μM), MDL-28170 (calpain-1 inhibitor), LY-333531 (PKC-β inhibitor), NAC (ROS inhibitor) and calpain-1 overexpression. Then, factors related to mitochondrial dysfunction, oxidative stress and VED were measured. Key findingsThe administration of Rg1 and calpain-1 knockout ameliorated diabetic mitochondrial dysfunction, oxidative stress and VED and inhibited the calpain-1/ROS/PKC-β axis. LY-333531 and NAC treatment restored destructive endothelium-dependent vasodilation in mice with diabetes, while pyrogallol (ROS agonist), PMA (PKC-β agonist) or L-NAME (eNOS inhibitor) treatment abrogated the protective effect of Rg1 against diabetic endothelial dysfunction. The administration of Rg1, MDL-28170, LY-333531 and NAC improved mitochondrial dysfunction, oxidative stress and VED, whereas the overexpression of calpain-1 amplified mitochondrial dysfunction, oxidative stress and VED and further upregulated the expression of PKC-β in HAECs exposed to HG. Overexpression of calpain-1 abrogated the protective effect of Rg1 against HG-induced oxidative stress and VED. SignificanceThese findings reveal that Rg1 can protect against VED by suppressing the calpain-1/ROS/PKC-β axis and alleviating the development of mitochondrial dysfunction and oxidative stress.

Platelet indices as a predictor of microvascular complications of type 2 diabetes mellitus

Abstract Background: The burden of diabetes is increasing day by day, and diabetic individuals are predisposed to develop micro- and macrovascular complications leading to increased mortality and morbidity. Platelet indexes can alert us regarding endothelial dysfunction in diabetes and in turn regarding microvascular complications. Materials and Methods: A case–control study was conducted on 100 diabetic patients with age and sex matched and 100 nondiabetic controls. All diabetic patients were evaluated for microvascular complications such as diabetic neuropathy, retinopathy, and nephropathy. Clinical history of all patients was taken regarding associated comorbidities and association. Fasting and postprandial blood sugar, HbA1c, platelet count, and platelet indices were measured. Statistical analysis was performed by using student unpaired t test and χ2 test. Results: Platelet indices mean platelet volume, plateletcrit, platelet distribution width (PDW), and platelet large cell ratio (P-LCR) were significantly higher in diabetic patients compared with controls. It was also observed that changes in mean platelet volume, PDW, and P-LCR were more significant in diabetic patients with microvascular complications than diabetic patients without microvascular complications. Conclusion: Values of platelet indices were statistically associated with diabetes and its microvascular complications.

Physiological concentration of protocatechuic acid directly protects vascular endothelial function against inflammation in diabetes through Akt/eNOS pathway.

Cardiovascular diseases (CVDs) have been the major cause of mortality in type 2 diabetes. However, new approaches are still warranted since current diabetic medications, which focus mainly on glycemic control, do not effectively lower cardiovascular mortality rate in diabetic patients. Protocatechuic acid (PCA) is a phenolic acid widely distributed in garlic, onion, cauliflower and other plant-based foods. Given the anti-oxidative effects of PCA in vitro, we hypothesized that PCA would also have direct beneficial effects on endothelial function in addition to the systemic effects on vascular health demonstrated by previous studies. Since IL-1β is the major pathological contributor to endothelial dysfunction in diabetes, the anti-inflammatory effects of PCA specific on endothelial cells were further verified by the use of IL-1β-induced inflammation model. Direct incubation of db/db mouse aortas with physiological concentration of PCA significantly ameliorated endothelium-dependent relaxation impairment, as well as reactive oxygen species overproduction mediated by diabetes. In addition to the well-studied anti-oxidative activity, PCA demonstrated strong anti-inflammatory effects by suppressing the pro-inflammatory cytokines MCP1, VCAM1 and ICAM1, as well as increasing the phosphorylation of eNOS and Akt in the inflammatory endothelial cell model induced by the key player in diabetic endothelial dysfunction IL-1β. Upon blocking of Akt phosphorylation, p-eNOS/eNOS remained low and the inhibition of pro-inflammatory cytokines by PCA ceased. PCA exerts protection on vascular endothelial function against inflammation through Akt/eNOS pathway, suggesting daily acquisition of PCA may be encouraged for diabetic patients.

Comprehensive analysis of m6A modification lncRNAs in high glucose and TNF-α induced human umbilical vein endothelial cells.

N6-methyladenosine (m6A) RNA methylation, as a reversible epigenetic modification of mammalian mRNA, holds a critical role in multiple biological processes. m6A modification in Long non-coding RNAs (lncRNAs) has increasingly attracted more attention in recent years, especially in diabetics, with or without metabolic syndrome. We investigated via m6A-sequencing and RNA-sequencing the differentially expressed m6A modification lncRNAs by high glucose and TNF-α induced endothelial cell dysfunction in human umbilical vein endothelial cells. Additionally, gene ontology and kyoto encyclopedia of genes and genomes analyses were performed to analyze the biological functions and pathways for the target of mRNAs. Lastly, a competing endogenous RNA network was established to further reveal a regulatory relationship between lncRNAs, miRNAs and mRNAs. A total of 754 differentially m6A-methylated lncRNAs were identified, including 168 up-regulated lncRNAs and 266 down-regulated lncRNAs. Then, 119 significantly different lncRNAs were screened out, of which 60 hypermethylated lncRNAs and 59 hypomethylated lncRNAs. Moreover, 122 differentially expressed lncRNAs were filtered, containing 14 up-regulated mRNAs and 18 down-regulated lncRNAs. Gene ontology and kyoto encyclopedia of genes and genomes analyses analyses revealed these targets were mainly associated with metabolic process, HIF-1 signaling pathway, and other biological processes. The competing endogenous RNA network revealed the regulatory relationship between lncRNAs, miRNAs and mRNAs, providing potential targets for the treatment and prevention of diabetic endothelial cell dysfunction. This comprehensive analysis for lncRNAs m6A modification in high glucose and TNF-α-induced human umbilical vein endothelial cells not only demonstrated the understanding of characteristics of endothelial cell dysfunction, but also provided the new targets for the clinical treatment of diabetes. Private information from individuals will not be published. This systematic review also does not involve endangering participant rights. Ethical approval will not be required. The results may be published in a peer-reviewed journal or disseminated at relevant conferences.

Hyperglycemia-Suppressed SMARCA5 Disrupts Transcriptional Homeostasis to Facilitate Endothelial Dysfunction in Diabetes.

Dysfunction of vascular endothelial cells (ECs) plays a central role in the pathogenesis of cardiovascular complications in diabetes. SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A member 5 (SMARCA5) is a key regulator of chromatin structure and DNA repair, but its role in ECs remains surprisingly unexplored. The current study was designed to elucidate the regulated expression and function of SMARCA5 in diabetic ECs. SMARCA5 expression was evaluated in ECs from diabetic mouse and human circulating CD34+ cells using quantitative reverse transcription polymerase chain reaction and Western blot. Effects of SMARCA5 manipulation on ECs function were evaluated using cell migration, in vitro tube formation and in vivo wound healing assays. Interaction among oxidative stress, SMARCA5 and transcriptional reprogramming was elucidated using luciferase reporter assay, electrophoretic mobility shift assay and chromatin immunoprecipitation. Endothelial SMARCA5 expression was significantly decreased in diabetic rodents and humans. Hyperglycemia-suppressed SMARCA5 impaired EC migration and tube formation in vitro, and blunted vasculogenesis in vivo. Contrarily, overexpression of SMARCA5 in situ by a SMARCA5 adenovirus-incorporated hydrogel effectively promoted the rate of wound healing in a dorsal skin punch injury model of diabetic mice. Mechanistically, hyperglycemia-elicited oxidative stress suppressed SMARCA5 transactivation in a signal transducer and activator of transcription 3 (STAT3)-dependent manner. Moreover, SMARCA5 maintained transcriptional homeostasis of several pro-angiogenic factors through both direct and indirect chromatin-remodeling mechanisms. In contrast, depletion of SMARCA5 disrupted transcriptional homeostasis to render ECs unresponsive to established angiogenic factors, which ultimately resulted in endothelial dysfunction in diabetes. Suppression of endothelial SMARCA5 contributes to, at least in part, multiple aspects of endothelial dysfunction, which may thereby exacerbate cardiovascular complications in diabetes.

Ginkgolide B caused the activation of the Akt/eNOS pathway through the antioxidant effect of SOD1 in the diabetic aorta.

Ginkgo biloba extract (GBE) helps lower cardiovascular disease risk. Diabetes mellitus (DM)-induced endothelial dysfunction is a critical and initiating factor in the beginning of diabetic vascular complications. It was reported that GBE causes an endothelial-dependent relaxation. This study was designed to figure out the molecular basis on which GBE protects from endothelial dysfunction in diabetes because the underlying mechanisms are unclear. Studies were performed in a normal control group and streptozotocin/nicotinamide-induced DM group. In aortas, notably diabetic aortas, GBE, and ginkgolide B (GB), a constituent of GBE, produced a dose-dependent relaxation. The relaxation by GB was abolished by prior incubation with L-NNA (an endothelial nitric oxide synthase (NOS) inhibitor), LY294002 (a phosphoinositide 3-kinase (PI3K) inhibitor), and Akt inhibitor, confirming the essential role of PI3K/Akt/eNOS signaling pathway. We also demonstrated that GB induced the phosphorylation of Akt and eNOS in aortas. The superoxide dismutase1 (SOD1) expression level decreased in DM aortas, but GB stimulation increased SOD activity and SOD1 expression in DM aortas. Our novel findings suggest that in DM aortas, endothelial-dependent relaxation induced by GB was mediated by activation of SOD1, resulting in activation of the Akt/eNOS signaling pathway.

Astragalus polysaccharide ameliorates vascular endothelial dysfunction by stimulating macrophage M2 polarization via potentiating Nrf2/HO-1 signaling pathway

BackgroundOxidative stress and chronic non-infectious inflammation caused vascular endothelial dysfunction (VED) is a critical and initiating factor in Type 2 diabetes induced vascular complications, while macrophage polarization plays a regulatory role in VED. Astragalus polysaccharide (APS) has been widely used for treating diabetic vascular diseases, but its mechanisms of action have not been fully elucidated. PurposeThis study aimed to investigate the modulatory effects of APS on macrophage polarization and to reveal the potential mechanisms of APS in LPS and HG stimulated macrophages and diabetic model rats. MethodsIn vitro and in vivo studies were used to explore the mechanism of APS. The macrophage polarization and reactive oxygen species (ROS) release was monitored by flow cytometry and the associated inflammatory factors were detected by ELISA. For oxidative stress regulatory pathway detection, protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and Heme oxygenase-1 (HO-1) was measured by Western blotting. The vascular endothelial functions were measured by transwell, tube formation assay, scratch assay, adhesion assay. The thoracic aorta pathological changes were evaluated by Haematoxylin-eosin and immunohistochemistry. ResultsIn vitro, APS inhibited the LPS/HG-stimulated THP-1 macrophage differentiated into macrophage M1, coupling with reduction in the ROS production and pro-inflammatory factors (TNF-α, IL-6, IL-12) release. Furthermore, endothelial cells proliferation and apoptosis were ameliorated after APS treatment. Meanwhile, APS-treated THP-1/macrophage occurred a differentiation into M2 polarization and anti-inflammatory factors (IL-4, IL-10, and Arg-1) release via enhancing Nrf2/HO-1 signaling pathway, which could be disturbed by using siNrf2. APS promoted the migration and angiogenesis of endothelial cells in co-cultured of HUVECs and macrophages under high glucose. Finally, similar results were observed in vivo, APS alleviated thoracic aorta complications of diabetic rats accompanied by a remarkable reduction in inflammation and an increased in the number of anti-inflammatory macrophage polarization. ConclusionOur results demonstrated that APS ameliorated vascular endothelial dysfunction in diabetes by stimulating macrophage polarization to M2 via enhancing the Nrf2/HO-1 pathway.

The vicious circle of UHRF1 down-regulation and KEAP1/NRF2/HO-1 pathway impairment promotes oxidative stress-induced endothelial cell apoptosis in diabetes.

Oxidative stress is recognized as a key factor in the induction of endothelial dysfunction in diabetes. However, the specific mechanisms have not been fully elucidated. We herein hypothesized that ubiquitin-like containing PHD and RING finger domains 1 (UHRF1) might have a role in oxidative stress-induced endothelial cell (EC) apoptosis in diabetes. Western blot, qPCR, wound healing assay, apoptosis assay, reactive oxygen species (ROS) detection, dual-luciferase reporter assay, methylation-specific PCR, bisulfite sequencing PCR and chromatin immunoprecipitation assay were performed. UHRF1 expression levels were significantly decreased in endothelial colony-forming cells derived from peripheral blood of participants with type 2 diabetes compared with individuals without diabetes. ECs treated with high glucose, palmitate or hydrogen peroxide in vitro also exhibited decreased UHRF1 protein levels. Silencing of UHRF1 led to decreased migration ability and increased apoptosis and ROS production in ECs, which might be related to impaired Kelch-like ECH-associated protein 1 (KEAP1)/nuclear factor erythroid 2-related factor 2 (NRF2)/haeme oxygenase-1 pathway. Mechanistically, UHRF1 is closely implicated in epigenetic regulation of chromatin modification status at KEAP1 genomic locus via histone acetylation. NRF2 down-regulation in turn inhibits UHRF1 protein level, which might be due to increased ROS generation. Diabetes-induced oxidative stress can mediate down-regulation of UHRF1, which enhances ROS production by regulating KEAP1/p-NRF2 pathway through histone acetylation and might also form a self-perpetuating feedback loop with KEAP1/p-NRF2 to further promote oxidative stress-induced apoptosis of ECs in diabetes.

Apigenin alleviates diabetic endothelial dysfunction through activating AMPK/PI3K/Akt/eNOS and Nrf2/HO‐1 signaling pathways

AbstractApigenin (4′,5,7‐trihydroxyflavone) is a natural flavone reported to present anti‐diabetic and anti‐oxidative bioactivities. The effect of apigenin to mitigate endothelial dysfunction in diabetes remains to be investigated. In the present study, the vaso‐protective effect of apigenin as well as its underlying action mechanisms was investigated using in vitro‐ and in vivo‐based assays. Aortas were detached from C57BL/6J mice for ex vivo treatment, and primary rat aortic endothelial cells (RAECs) were cultured and further stimulated using high glucose (HG) with or without apigenin. In‐vivo diabetic model was established by feeding male C57BL/6J mice with a high‐fat diet (60% kcal% fat) for a total of 14 weeks, whereas the treatment group was orally administered apigenin (25 mg/kg/day) during the last 4 weeks. Exposure to HG (30 mM, 48 h) impaired acetylcholine‐induced endothelium‐dependent relaxation (EDR) in mouse aortas and induced oxidative stress with the downregulation of adenosine 5'‐monophosphate (AMP)‐activated protein kinase (AMPK)/phosphatidyl inositol 3‐kinase (PI3K)/protein kinase B (Akt)/endothelial nitric oxide synthase (eNOS) and nuclear factor erythroid 2‐related factor 2 (Nrf2)/heme oxygenase 1 (HO‐1) signaling pathways in aortas and RAECs. These impairments were reversed by apigenin treatments. However, the vaso‐protective effects of apigenin were abolished by Compound C (AMPK inhibitor) and wortmannin (PI3K inhibitor). Chronic oral administration with apigenin ameliorated EDR and reduced oxidative stress in the aortas of high‐fat diet (HFD)‐induced obese and diabetic mice. In conclusion, this study revealed that apigenin improved endothelial function and suppressed oxidative stress in the vasculature in diabetes through the activation of AMPK/PI3K/Akt/eNOS and Nrf2/HO‐1 pathways, suggesting its therapeutic potential as a natural dietary flavonoid against vascular diseases associated with diabetes.

Effects of sub-chronic, in vivo administration of sigma-1 receptor ligands on platelet and aortic arachidonate cascade in streptozotocin-induced diabetic rats.

Diabetes mellitus is a chronic metabolic disorder which induces endothelial dysfunction and platelet activation. Eicosanoids produced from arachidonic acid regulate cellular and vascular functions. Sigma-1 receptors (S1R) are expressed in platelets and endothelial cells and S1R expression is protective in diabetes. Our aim was to examine the influence of sub-chronic, in vivo administered S1R ligands PRE-084, (S)-L1 (a new compound) and NE-100 on the ex vivo arachidonic acid metabolism of platelets and aorta in streptozotocin-induced diabetic rats. The serum level of the S1R ligands was detected by LC-MS/MS before the ex vivo analysis. Sigma-1 receptor and cyclooxygenase gene expression in platelets were determined by RT-qPCR. The eicosanoid synthesis was examined with a radiolabelled arachidonic acid substrate and ELISA. One month after the onset of STZ-induced diabetes, in vehicle-treated, diabetic rat platelet TxB2 and aortic 6-k-PGF1α production dropped. Sub-chronic in vivo treatment of STZ-induced diabetes in rats for one week with PRE-084 enhanced vasoconstrictor and platelet aggregator and reduced vasodilator and anti-aggregator cyclooxygenase product formation. (S)-L1 reduced the synthesis of vasodilator and anti-aggregator cyclooxygenase metabolites and promoted the recovery of physiological platelet function in diabetic rats. The S1R antagonist NE-100 produced no significant changes in platelet arachidonic acid metabolism. (S)-L1 decreased the synthesis of vasoconstrictor and platelet aggregator cyclooxygenase metabolites, whereas NE-100 increased the quantity of aortic vasodilator and anti-aggregator cyclooxygenase products and promoted the recovery of diabetic endothelial dysfunction in the aorta. The novel S1R ligand, (S)-L1 had similar effects on eicosanoid synthesis in platelets as the agonist PRE-084 and in aortas as the antagonist NE-100. S1R ligands regulate cellular functions and local blood circulation by influencing arachidonic acid metabolism. In diabetes mellitus, the cell-specific effects of S1R ligands have a compensatory role and aid in restoring physiological balance between the platelet and vessel.

Abstract 15377: Investigating the Role of Breast Cancer Susceptibility Gene 2 in High Glucose-Induced Endothelial Dysfunction

Introduction and Hypothesis: Mutations in the breast cancer susceptibility gene 2 (BRCA2) impair DNA damage repair which can eventually culminate in cancer, inflammation and/or apoptosis. Hyperglycemia-induced oxidative stress triggers DNA damage, inflammation and apoptosis, which are common contributors to endothelial dysfunction in diabetes. Here, we assessed the hypothesis that BRCA2 plays critical role in hyperglycemia-induced endothelial dysfunction. Methods and Results: Human umbilical vein endothelial cells (HUVECs) were exposed to high- (HG; 25 mM) or normal glucose (NG; 5 mM) and BRCA2 expression was measured. Our data showed significant BRCA2 upregulation in HG-treated HUVECs. Next, we successfully silenced BRCA2 in HUVECs, and measured the expression levels of p53 and p21 in HG- and NG-treated BRCA2-silenced HUVECs. We observed a significant upregulation of p53 and p21 in BRCA2-deficient HUVECs, which was further augmented by HG. Next, we measured the migratory and angiogenic potential of control and BRCA2-seilenced HUVECs under NG and HG. Our preliminary data showed that HG and loss of BRCA2 together inhibited the migratory capacity and angiogenic potential of HUVECs. To understand the mechanism behind the effect of HG on BRCA2-deficient ECs, we measured expression levels of endothelial nitric oxide synthase (eNOS). Both expression and activation of eNOS was reduced in HG-treated BRCA2-deficient HUVECs. To understand the effect of loss of BRCA2 on overall endothelial transcriptome and to understand mechanisms, we performed RNA sequencing on scrambled control- and siBRCA2-transfected HUVECs. Interestingly, a total of 3150 genes were differentially expressed in BRCA2-deficient HUVECs compared to the control group. Conclusion: Collectively, these findings reveal a novel role for BRCA2 as a regulator of endothelial function in context of HG treatment in vitro . Our RNA sequencing data shows theimportance of BRCA2 in regulating endothelial transcriptome and overall endothelial function. Further studies are underway; however, these results may provide important implications concerning the susceptibility of BRCA2 mutation carriers to HG-induced endothelial dysfunction as well as other CVDs.

Jatrorrhizine Improves Endothelial Function in Diabetes and Obesity through Suppression of Endoplasmic Reticulum Stress.

Jatrorrhizine (JAT) is one of the major bioactive protoberberine alkaloids found in rhizoma coptidis, which has hypoglycemic and hypolipidemic potential. This study aimed to evaluate the vasoprotective effects of JAT in diabetes and obesity and the underlying mechanism involved. Mouse aortas, carotid arteries and human umbilical cord vein endothelial cells (HUVECs) were treated with risk factors (high glucose or tunicamycin) with and without JAT ex vivo and in vitro. Furthermore, aortas were obtained from mice with chronic treatment: (1) control; (2) diet-induced obese (DIO) mice fed a high-fat diet (45% kcal% fat) for 15 weeks; and (3) DIO mice orally administered JAT at 50 mg/kg/day for the last 5 weeks. High glucose or endoplasmic reticulum (ER) stress inducer tunicamycin impaired acetylcholine-induced endothelium-dependent relaxations (EDRs) in mouse aortas, induced oxidative stress in carotid arteries and HUVECs, downregulated phosphorylations of Akt at Ser473 and eNOS at Ser1177 and enhanced ER stress in mouse aortas and HUVECs, and these impairments were reversed by cotreatment with JAT. JAT increased NO release in high-glucose-treated mouse aortas and HUVECs. In addition, chronic JAT treatment restored endothelial function with EDRs comparable to the control, increased Akt/eNOS phosphorylation, and attenuated ER stress and oxidative stress in aortas from DIO mice. Blood pressure, glucose sensitivity, fatty liver and its morphological change, as well as plasma levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and plasma lipid profile, were also normalized by JAT treatment. Collectively, our data may be the first to reveal the vasoprotective effect of JAT that ameliorates endothelial dysfunction in diabetes and obesity through enhancement of the Akt/eNOS pathway and NO bioavailability, as well as suppression of ER stress and oxidative stress.

Adverse epigenetic signatures driven by histone methyltransferase EZH2 contribute to hyperglycaemia-induced endothelial dysfunction

Abstract Introduction Posttranslational modifications of histones play a critical role in regulating gene expression in health and disease. Activation of histone methyltransferase enhancer of zeste homolog 2 (EZH2) catalyses repressive trimethylation of histone 3 at lysine residue 27 (H3K27me3) and favours reactive oxygen species (ROS) generation as well as pro-inflammatory changes. Oxidative stress and inflammation are linked to hyperglycaemia-induced endothelial dysfunction. Purpose The present study was designed to investigate whether EZH2 may represent a novel therapeutic target against hyperglycaemia-induced abnormal phenotypes in the endothelium. Methods The effect of EZH2 was tested in aortas from male mice (3–5 months old), human aortic endothelial cells (HAECs) and aortic endothelial cells isolated from diabetic individuals (D-HAECs) in the presence and in the absence of pharmacological inhibitor GSK126 (5 μM) or gene silencing of EZH2. HAECs and aortic rings were exposed either to normal glucose (5 mM) or high glucose (25 mM) for 20 hrs. Expression levels of H3K27me3, EZH2, oxidant and pro-inflammatory genes were determined by RT-PCR, western blotting, and protein activation assay kits. Superoxide anion production was measured by electron spin resonance spectroscopy. Binding of H3K27me3 to the promoter region of candidate genes was evaluated by chromatin immunoprecipitation (ChIP). Endothelium-dependent and independent relaxations were assessed in aortic rings by organ chamber experiments. Results Immunoblotting showed a significant increase in EZH2 activity measured as H3K27me3 in HAECs exposed to high glucose and in D-HAEC. ChIP assays showed that binding of H3K27me3 to the promoter of anti-oxidant and transcription factor JunD genes triggers ROS generation and activation of inflammatory pathways. Interestingly enough, histone methyltransferase EZH2 inhibitor GSK126 or specific siRNA blunting H3K27me3 abolished hyperglycaemia-induced oxidative stress and inflammation. Moreover, targeting EZH2 rescued endothelial function. Conclusions These results uncover adverse epigenetic signatures underlying endothelial dysfunction in diabetes. Targeting EZH2 may attenuate oxidative and inflammatory transcriptional programmes and thus prevent vascular disease in this setting. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Swedish Research Council, the Swedish Heart & Lung Foundation, and King Gustav V and Queen Victoria Foundation.

Vaccarin alleviates endothelial inflammatory injury in diabetes by mediating miR-570-3p/HDAC1 pathway.

Vaccarin is a flavonoid glycoside, which has a variety of pharmacological properties and plays a protective role in diabetes and its complications, but its mechanism is unclear. In this study, we aim to investigate whether histone deacetylase 1(HDAC1), a gene that plays a pivotal role in regulating eukaryotic gene expression, is the target of miR-570-3p in diabetic vascular endothelium, and the potential molecular mechanism of vaccarin regulating endothelial inflammatory injury through miR-570-3p/HDAC1 pathway. The HFD and streptozotocin (STZ) induced diabetes mice model, a classical type 2 diabetic model, was established. The aorta of diabetic mice displayed a decrease of miR-570-3p, the elevation of HDAC1, and inflammatory injury, which were alleviated by vaccarin. Next, we employed the role of vaccarin in regulating endothelial cells miR-570-3p and HDAC1 under hyperglycemia conditions in vitro. We discovered that overexpression of HDAC1 counteracted the inhibitory effect of vaccarin on inflammatory injury in human umbilical vein endothelial cells (HUVECs). Manipulation of miRNA levels in HUVECs was achieved by transfecting cells with miR-570-3p mimic and inhibitor. Overexpression of miR-570-3p could decrease the expression of downstream components of HDAC1 including TNF-α, IL-1β, and malondialdehyde, while increasing GSH-Px activity in HUVECs under hyperglycemic conditions. Nevertheless, such phenomenon was completely reversed by miR-570-3p inhibitor, and administration of miR-570-3p inhibitor could block the inhibition of vaccarin on HDAC1 and inflammatory injury. Luciferase reporter assay confirmed the 3′- UTR of the HDAC1 gene was a direct target of miR-570-3p. In summary, our findings suggest that vaccarin alleviates endothelial inflammatory injury in diabetes by mediating miR-570-3p/HDAC1 pathway. Our study provides a new pathogenic link between deregulation of miRNA expression in the vascular endothelium of diabetes and inflammatory injury and provides new ideas, insights, and choices for the scope of application and medicinal value of vaccarin and some potential biomarkers or targets in diabetic endothelial dysfunction and vascular complications.

Roles of Reactive Oxygen Species in Vascular Complications of Diabetes: Therapeutic Properties of Medicinal Plants and Food

The rising prevalence of chronic metabolic disorders, such as obesity and type 2 diabetes, most notably associated with cardiovascular diseases, has emerged as a major global health concern. Reactive oxygen species (ROS) play physiological functions by maintaining normal cellular redox signaling. By contrast, a disturbed balance occurring between ROS production and detoxification of reactive intermediates results in excessive oxidative stress. Oxidative stress is a critical mediator of endothelial dysfunction in obesity and diabetes. Under a hyperglycemic condition, the antioxidant enzymes are downregulated, resulting in an increased generation of ROS. Increases in ROS lead to impairment of endothelium-dependent vasodilatations by reducing NO bioavailability. Chronic treatments with antioxidants were reported to prevent the development of endothelial dysfunction in diabetic patients and animals; however, the beneficial effects of antioxidant treatment in combating vascular complications in diabetes remain controversial as antioxidants do not always reverse endothelial dysfunction in clinical settings. In this review, we summarize the latest progress in research focused on the role of ROS in vascular complications of diabetes and the antioxidant properties of bioactive compounds from medicinal plants and food in animal experiments and clinical studies to provide insights for the development of therapeutic strategies.

Effect of fenofibrate in comparison to metformin on the biophysical and biochemical parameters in diabetic albino wistar rats

Introduction: Diabetic endothelial dysfunction is accompanied by increased oxidative stress and upregulated proinflammatory and inflammatory mediators in the endothelial vasculature. Activation of peroxisome proliferator-activated receptor-alpha (PPAR-α) results in antioxidant and anti-inflammatory effects. Aim of this study is to investigate the effect of fenofibrate, a PPAR-α activator, on the oxidative stress, inflammation and its anti-oxidant effect in streptozotocin diabetic rats and to compare the effectiveness of FF with that of Metformin (Met). Material & Methods: This experimental animal study was conducted at animal house. The sample size included 174 albino wistar rats divided into 3 Groups, one control groups (C )Diabetic and untreated and two test groups .T1 -Diabetic and treated with metformin 75 mg/kgwt/day) and T2 (T – Diabetics treated with fenofibrate 100 mg/kgwt/day), with 58 rats in each group (29 male & 29 female). All the rats were treated with streptozotocin intra peritoneally and the diabetic state was induced. T1 group was treated with metformin 75 mg/kg/wt/day. The T2 group of rats were treated with Feno fibrate (FF) at a dose of 100 mg/kgwt/day.

PROTECTIVE EFFECT OF MITOTEMPO IN STREPTOZOTOCIN-INDUCED DIABETIC RAT MODEL: EFFECTS ON CORPUS CAVERNOSUM AND AORTA

Objective: In this study we aimed to evaluate the effect of mitotempo, a mitochondria-specific antioxidant, on endothelial and erectile dysfunction in a Streptozotocin-induced rat diabetes model. Material and Methods: Wistar Albino rats weighing 280-320 g were used in the study. Diabetes was induced by intraperitoneal 50 mg/kg single dose streptozotocin injection. Blood glucose levels above 300 mg/dl at the end of 1 week were considered diabetes. Blood glucose was monitored for 4 weeks. The treatment group received mitotempo orally at 0.7 mg/kg/ day for 4 weeks. At the end of the 4th week, the aorta and corpus cavernosum contraction and relaxation responses were evaluated in an isolated organ bath after decapitation. Results: According to our study results, mitotempo 0.7 mg/kg/day for 4 weeks in a diabetes model preserved endothelial relaxation responses in both the thoracic aorta and corpus cavernosum. Phenylephrine contractions calculated according to KCl contraction did not differ between the groups. Conclusion: Endothelial cells can be identified as one of the first organs to be exposed to circulating substances. The effects of mROS on endothelial dysfunction caused by hyperglycemia is known. In our study, we found that a 0.7 mg/kg/day mitotempo treatment for 4 weeks showed protective effects on STZ-induced diabetic endothelial dysfunction.

Inhibitory Effects of Saururus chinensis Extract on Receptor for Advanced Glycation End-Products-Dependent Inflammation and Diabetes-Induced Dysregulation of Vasodilation

Advanced glycation end-products (AGEs) and the receptor for AGEs (RAGE) are implicated in inflammatory reactions and vascular complications in diabetes. Signaling pathways downstream of RAGE are involved in NF-κB activation. In this study, we examined whether ethanol extracts of Saururus chinensis (Lour.) Baill. (SE) could affect RAGE signaling and vascular relaxation in streptozotocin (STZ)-induced diabetic rats. Treatment with SE inhibited AGEs-modified bovine serum albumin (AGEs-BSA)-elicited activation of NF-κB and could compete with AGEs-BSA binding to RAGE in a dose-dependent manner. Tumor necrosis factor-α (TNF-α) secretion induced by lipopolysaccharide (LPS)—a RAGE ligand—was also reduced by SE treatment in wild-type Ager+/+ mice as well as in cultured peritoneal macrophages from Ager+/+ mice but not in Ager−/− mice. SE administration significantly ameliorated diabetes-related dysregulation of acetylcholine-mediated vascular relaxation in STZ-induced diabetic rats. These results suggest that SE would inhibit RAGE signaling and would be useful for the improvement of vascular endothelial dysfunction in diabetes.

Effect of berberine in comparison to metformin on the biophysical and biochemical parameters in diabetic albino Wistar rats

Introduction: Diabetic endothelial dysfunction is accompanied by increased oxidative stress and upregulated proinflammatory and inflammatory mediators in the endothelial vasculature. Aim of this study is to investigate the effect of Berberine, a natural alkaloid, on the oxidative stress, inflammation and its anti-oxidant effect in streptozotocin diabetic rats and to compare the effectiveness of FF with that of Metformin (Met) Material & Methods: This experimental animal study was conducted at animal house. The sample size included 174 albino wistar rats divided into 3 Groups, one control groups (C) Diabetic and untreated and two test groups. T1 Diabetic and treated with metformin 75 mg/kgwt/day) and T2 (T – Diabetics treated with Berberine(Ber) 100 mg/kgwt/day), with 58 rats in each group (29 male & 29 female). All the rats were treated with streptozotocin intra peritoneally and the diabetic state was induced. T1 group was treated with metformin 75 mg/kg/wt/day. The T2 group of rats were treated with Berberine at a dose of 100 mg/kgwt/day. Blood sample was drawn from retro orbital plexus of animals and the biophysical and biochemical parameters were tested at an interval of 3, 6 and 12-months duration.