MiR-181b suppresses angiogenesis by directly targeting cellular communication network factor 1

Angiogenesis is essential for various physiological and pathological processes. Previous studies have shown that miRNAs play an important role in blood vessel development and angiogenesis. Recent studies have suggested that miR-181b might be involved in the regulation of angiogenesis in tumors. However, whether miR-181b plays a role in angiogenesis in nontumor diseases is unclear. We found that miR-181b expression was downregulated in hypoxia-stimulated primary human umbilical vein endothelial cells (HUVECs) and a mouse hindlimb ischemia (HLI) model. Gain- and loss-of-function studies showed that a miR-181b mimic inhibited HUVEC migration and tube formation in vitro, and a miR-181b inhibitor had the opposite effects. In vivo, agomir-181b suppressed perfusion recovery in the HLI model and capillary density in a Matrigel plug assay, while perfusion recovery and capillary density were increased by injection of antagomir-181b. Mechanistically, we showed with a reporter assay that cellular communication network factor 1 (CCN1) was a direct target of miR-181b. Moreover, miR-181b suppressed angiogenesis at least in part by targeting CCN1 to inhibit the AMPK signaling pathway. Our research suggests that miR-181b suppresses angiogenesis by directly targeting CCN1, which provides new clues for pro-angiogenic treatment strategies.

Improved Endothelium-Dependent Relaxation of Thoracic Aorta in Niclosamide-Treated Diabetic Rats

Diabetes-induced endothelial dysfunction is critical for the development of diabetic cardiovascular complications. The aim of this study was to investigate the effect of niclosamide (Nic) on vascular endothelial dysfunction in streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats were injected with a single intraperitoneal injection of STZ (75 mg/kg) to induce type 1 diabetes, and Nic (10 mg/kg) was intraperitoneally administered per day for 4 weeks. Endothelial function was evaluated as carbachol (CCh, an endothelium-dependent vasodilator)-evoked relaxation in the experiments performed on isolated thoracic aortas. The changes in the protein expressions of phosphorylated eNOS at serine 1177 (p-eNOSSer1177) and phosphorylated VASP at serine 239 (p-VASPSer239) of the rat aortas were analyzed by western blotting to determine whether NO/cGMP signaling is involved in the mechanism of Nic. STZ-injected rats had higher fasting blood glucose and less body weight compared to control rats (p < 0.05). Nic treatment did not affect blood glucose levels or body weights of the rats. CCh-induced endothelium-dependent relaxation of the aortic rings was significantly decreased in diabetic rats compared to control (Emax = 66.79 ± 7.41% and 90.28 ± 5.55%, respectively; p < 0.05). CCh-induced relaxation response was greater in Nic-treated diabetic rats compared to diabetic rats (Emax = 91.56 ± 1.20% and 66.79 ± 7.41%, respectively; p < 0.05). Phosphorylation of eNOS and VASP in aortic tissues was significantly reduced in diabetic rats, which were markedly increased by Nic treatment (p < 0.05). We demonstrated that Nic improved endothelial dysfunction possibly through the activation of NO/cGMP signaling without affecting hyperglycemia in diabetic rats. Our results suggesting that Nic has potential of repurposing for diabetic cardiovascular complications.

Fasting and fasting-mimicking treatment activate SIRT1/LXRα and alleviate diabetes-induced systemic and microvascular dysfunction

AIMS/HYPOTHESIS

Homo sapiens evolved under conditions of intermittent food availability and prolonged fasting between meals. Periods of fasting are important for recovery from meal-induced oxidative and metabolic stress, and tissue repair. Constant high energy-density food availability in present-day society contributes to the pathogenesis of chronic diseases, including diabetes and its complications, with intermittent fasting (IF) and energy restriction shown to improve metabolic health. We have previously demonstrated that IF prevents the development of diabetic retinopathy in a mouse model of type 2 diabetes (db/db); however the mechanisms of fasting-induced health benefits and fasting-induced risks for individuals with diabetes remain largely unknown. Sirtuin 1 (SIRT1), a nutrient-sensing deacetylase, is downregulated in diabetes. In this study, the effect of SIRT1 stimulation by IF, fasting-mimicking cell culture conditions (FMC) or pharmacological treatment using SRT1720 was evaluated on systemic and retinal metabolism, systemic and retinal inflammation and vascular and bone marrow damage.

METHODS

The effects of IF were modelled in vivo using db/db mice and in vitro using bovine retinal endothelial cells or rat retinal neuroglial/precursor R28 cell line serum starved for 24 h. mRNA expression was analysed by quantitative PCR (qPCR). SIRT1 activity was measured via histone deacetylase activity assay. NR1H3 (also known as liver X receptor alpha [LXRα]) acetylation was measured via western blot analysis.

RESULTS

IF increased Sirt1 mRNA expression in mouse liver and retina when compared with non-fasted animals. IF also increased SIRT1 activity eightfold in mouse retina while FMC increased SIRT1 activity and expression in retinal endothelial cells when compared with control. Sirt1 expression was also increased twofold in neuronal retina progenitor cells (R28) after FMC treatment. Moreover, FMC led to SIRT1-mediated LXRα deacetylation and subsequent 2.4-fold increase in activity, as measured by increased mRNA expression of the genes encoding ATP-binding cassette transporter (Abca1 and Abcg1). These changes were reduced when retinal endothelial cells expressing a constitutively acetylated LXRα mutant were tested. Increased SIRT1/LXR/ABC-mediated cholesterol export resulted in decreased retinal endothelial cell cholesterol levels. Direct activation of SIRT1 by SRT1720 in db/db mice led to a twofold reduction of diabetes-induced inflammation in the retina and improved diabetes-induced visual function impairment, as measured by electroretinogram and optokinetic response. In the bone marrow, there was prevention of diabetes-induced myeloidosis and decreased inflammatory cytokine expression.

CONCLUSIONS/INTERPRETATION

Taken together, activation of SIRT1 signalling by IF or through pharmacological activation represents an effective therapeutic strategy that provides a mechanistic link between the advantageous effects associated with fasting regimens and prevention of microvascular and bone marrow dysfunction in diabetes.

In Situ Photo-Cross-Linking Hydrogel Accelerates Diabetic Wound Healing through Restored Hypoxia-Inducible Factor 1-Alpha Pathway and Regulated Inflammation

The hypoxia-inducible factor 1-alpha (HIF-1a) pathway plays a key role in regulating angiogenesis during wound healing. However, the diabetic condition hampers the stabilization of HIF-1a and thus inhibits the subsequent angiogenesis, and meanwhile, the function and phenotype transition of macrophage are impaired in the diabetic condition, which leads to prolonged and chronic inflammation. Both angiogenesis inhibition and inflammatory dysfunction make diabetic wound healing a major clinical challenge. Here, borosilicate (BS), a new group of bioceramics with a coupled network of interconnected [BO₃] and [SiO₄] which can incorporate therapeutic ions such as Cu²⁺, is synthesized and combined with silk fibroin (SF), a biocompatible natural amino acid polymer whose composition and structure are similar to a natural extracellular matrix (ECM), to obtain a compound system which can transform into a SF-MA-BS hydrogel under UV radiation via methacryloyloxy (MA) groups modified on both BS and SF. When in use, the compound system can thoroughly spread to the whole wound surface and be in situ photo-cross-linked to form an integral SF-MA-BS hydrogel that firmly adheres to the wound, protects the wound from external contamination, and further spontaneously promotes wound regeneration by releasing therapeutic ions. The wound repair of Streptozotocin-induced diabetic rats shows that diabetic wound healing is obviously accelerated by SF-MA-BS, interestingly the HIF-1a pathway is restored via interaction between HIF-1a and Cu²⁺, and angiogenesis is therefore enhanced. Meanwhile, inflammation is well regulated by SF-MA-BS, and long-term detrimental inflammation is avoided. These findings indicate that the SF-MA-BS hydrogel regenerates diabetic wounds, and further clinical trials are anticipated.

Exogenous Hydrogen Sulfide Plays an Important Role by Regulating Autophagy in Diabetic-Related Diseases

Autophagy is a vital cell mechanism which plays an important role in many physiological processes including clearing long-lived, accumulated and misfolded proteins, removing damaged organelles and regulating growth and aging. Autophagy also participates in a variety of biological functions, such as development, cell differentiation, resistance to pathogens and nutritional hunger. Recently, autophagy has been reported to be involved in diabetes, but the mechanism is not fully understood. Hydrogen sulfide (H₂S) is a colorless, water-soluble, flammable gas with the typical odor of rotten eggs, which has been known as a highly toxic gas for many years. However, it has been reported recently that H₂S, together with nitric oxide and carbon monoxide, is an important gas signal transduction molecule. H₂S has been reported to play a protective role in many diabetes-related diseases, but the mechanism is not fully clear. Recent studies indicate that H₂S plays an important role by regulating autophagy in many diseases including cancer, tissue fibrosis diseases and glycometabolic diseases; however, the related mechanism has not been fully studied. In this review, we summarize recent research on the role of H₂S in regulating autophagy in diabetic-related diseases to provide references for future related research.

Lactucaxanthin protects retinal pigment epithelium from hyperglycemia-regulated hypoxia/ER stress/VEGF pathway mediated angiogenesis in ARPE-19 cell and rat model

Hyperglycemia mediated perturbations in biochemical pathways induce angiogenesis in diabetic retinopathy (DR) pathogenesis. The present study aimed to investigate the protective effects of lactucaxanthin, a predominant lettuce carotenoid, on hyperglycemia-mediated activation of angiogenesis in vitro and in vivo diabetic model. ARPE-19 cells cultured in 30 mM glucose concentration were treated with lactucaxanthin (5 μM and 10 μM) for 48 h. They were assessed for antioxidant enzyme activity, mitochondrial membrane potential, reactive oxygen species, and cell migration. In the animal experiment, streptozotocin-induced diabetic male Wistar rats were gavaged with lactucaxanthin (200 μM) for 8 weeks. Parameters like animal weight gain, feed intake, water intake, urine output, and fasting blood glucose level were monitored. In both models, lutein-treated groups were considered as a positive control. Hyperglycemia-mediated angiogenic marker expressions in ARPE-19 and retina of diabetic rats were quantified through the western blot technique. Expression of hypoxia, endoplasmic reticulum stress markers, and vascular endothelial growth factor were found to be augmented in the hyperglycemia group compared to control (P < 0.05). Hyperglycemia plays a crucial role in increasing cellular migration and reactive oxygen species besides disrupting tight junction protein. Compared to lutein, lactucaxanthin aids retinal pigment epithelium (RPE) function from hyperglycemia-induced stress conditions via downregulating angiogenesis markers expression. Lactucaxanthin potentiality observed in protecting tight junction protein expression via modulating reactive oxygen species found to conserve RPE integrity. Results demonstrate that lactucaxanthin exhibits robust anti-angiogenic activity for the first time and, therefore, would be useful as an alternative therapy to prevent or delay DR progression.

Scutellarin ameliorates high glucose-induced vascular endothelial cells injury by activating PINK1/Parkin-mediated mitophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellarin (Scu) is one of the main active ingredients of Erigeron breviscapus (Vant.) Hand.-Mazz which has been used to treat cardiovascular disease including vascular dysfunction caused by diabetes. Scu also has a protective effect on vascular endothelial cells against hyperglycemia. However, molecular mechanisms underlying this effect are not clear.

AIM OF THE STUDY

This aim of this study was to investigate the effect of Scu on human umbilical vein endothelial cells (HUVECs) injury induced by high glucose (HG), especially the regulation of PTEN-induced kinase 1 (PINK1)/Parkin-mediated mitophagy.

MATERIALS AND METHODS

HUVECs were exposed to HG to induce vascular endothelial cells injury in vitro. Cell viability was assessed by MTT assay. The extent of cell apoptosis was measured by Hoechst staining and flow cytometry. Mitophagy was assayed by fluorescent immunostaining, transmission electron microscope and immunoblot. Besides, virtual docking was conducted to validate the interaction of PINK1 protein and Scu.

RESULTS

We found that Scu significantly increased cell viability in HG-treated HUVECs. Scu reduces the expression of Bcl-2, Bax and cytochrome C (Cyt.c) to inhibit apoptosis through a mitochondria-dependent pathway. Meanwhile, Scu improved the overload of reactive oxygen species (ROS), superoxide dismutase (SOD) activity and SOD2 protein expression, and reversed the collapse of mitochondrial membrane potential. Besides, Scu increased autophagic flux, improved the expression of microtubule-associated protein 1 light chain 3 Ⅱ (LC3 II), Beclin 1 and autophagy-related gene 5 (Atg 5) and decreased the expression of Sequestosome1/P62 in HG-treated HUVECs. Furthermore, Scu improved the expressions of PINK1, Parkin, and Mitofusin2, which revealed the enhancement of mitophagy. Moreover, the beneficial effects of Scu on HG-induced low expression of Parkin, overproduction of ROS, and over expressions of P62, Cyt.c and Cleaved caspase-3 were weakened by PINK1 gene knockdown. Molecular docking suggested good interaction of Scu and PINK1 protein.

CONCLUSION

These results suggest that Scu may protect vascular endothelial cells against hyperglycemia-induced injury by up-regulating mitophagy via PINK1/Parkin signal pathway.

Body mass index, estimated glucose disposal rate and vascular complications in type 1 diabetes: Beyond glycated haemoglobin

AIMS

To understand the relationship between insulin resistance (IR), assessed as estimated glucose disposal rate (eGDR), and microvascular/macrovascular complications in people with type 1 diabetes.

MATERIALS AND METHODS

Individuals with a confirmed diagnosis of type 1 diabetes were included in this cross-sectional study. BMI was categorised into normal weight (18.0-24.9 kg m^-2 ), overweight (25.0-29.9 kg m^-2 ) and obese groups (≥30.0 kg m^-2 ). We categorised eGDR into four groups: eGDR >8, 6-7.9, 4-5.9 and <4 mg kg^-1  min^-1 . Multiple logistic regression was used to identify associations with vascular complications, after adjusting for relevant confounders.

RESULTS

A total of 2151 individuals with type 1 diabetes were studied. Median [interquartile range (IQR)] age was 41.0 [29.0, 55.0] with diabetes duration of 20.0 [11, 31] years. Odds ratio (OR) for retinopathy and nephropathy in obese compared with normal weight individuals was 1.64 (95% CI: 1.24-2.19; p = 0.001) and 1.62 (95% CI: 1.10-2.39; p = 0.015), while the association with cardiovascular disease just failed to reach statistical significance (OR 1.66 [95% CI: 0.97-2.86; p = 0.066]). Comparing individuals with eGDR ≥8 mg kg^-1  min^-1 and <4 mg kg^-1  min^-1 showed OR for retinopathy, nephropathy and macrovascular disease of 4.84 (95% CI: 3.36-6.97; p < 0.001), 8.35 (95% CI: 4.86-14.34; p < 0.001) and 13.22 (95% CI: 3.10-56.38; p < 0.001), respectively. Individuals with the highest eGDR category (≥8 mg kg^-1  min^-1 ) had the lowest complication rates irrespective of HbA_1c levels.

CONCLUSIONS

Obesity is prevalent in type 1 diabetes and diabetes complications are not only related to glucose control. IR, assessed as eGDR, is strongly associated with both microvascular and macrovascular complications, regardless of HbA_1c levels.

Mobilization of endothelial progenitor cells promotes angiogenesis after full thickness excision by AMD3100 combined with G-CSF in diabetic mice by SDF-1/CXCR4 axis

AIM

The aim of the present study was to investigate the effect of the mobilization of EPCs by AMD3100 combined with G-CSF on wound healing in diabetic mice.

METHODS

The full-thickness excisional wounds model of diabetic mice (db/db) was examined by hematoxylin and eosin staining, immunohistochemical staining, and western blotting to compare the wound healing and neovascularization among the combination, AMD3100 alone, G-CSF alone, and control groups.

RESULTS

The wounds reached the complete closure in the combination, AMD3100 alone, G-CSF alone, and control groups on days 17, 20, 21, 21 after surgery, respectively. In addition, the combination group promoted the inflammatory cell recruitment and glandular formation. On day 10 from injury, the protein expression of CD31 in the combination group was significantly higher compared with the other three groups (p < 0.001). The level of SDF-1 protein remained high in the combined group until on day 10 after surgery (p < 0.001).

CONCLUSION

The mobilization of endogenous EPCs by AMD3100 combine with G-CSF is able to enhance the complete healing of full-thickness wounds and neovascularization in db/db mice may by SDF-1/CXCR4 axis. These findings provided a novel method and indication of duration of mobilization on diabetic wound healing and tissue regeneration.

Activation of RAGE-dependent endoplasmic reticulum stress associates with exacerbated postmyocardial infarction ventricular arrhythmias in diabetes

Association between receptor for advanced glycation end products (RAGE) and postmyocardial infarction (MI) ventricular arrhythmias (VAs) in diabetes was investigated. Correlation between premature ventricular contractions (PVCs) and serum advanced glycation end products (AGEs) content was analyzed in a cohort consisting of 101 patients with ST-segment elevated MI (STEMI). MI diabetic rats were treated with anti-receptor for AGE (RAGE) antibody. Electrocardiography was used to record VAs. Myocytes were isolated from adjacent area around infracted region. Immunofluorescent stains were used to evaluate the association between FKBP12.6 (FK506-bindingprotein 12.6) and ryanodine receptor 2 (RyR2). Calcium sparks were evaluated by confocal microscope. Protein expression and phosphorylation were assessed by Western blotting. Calcineurin (CaN) enzymatic activity and RyR2 channel activity were also determined. In the cohort study, significantly increased amount of PVC was found in STEMI patients with diabetes (P < 0.05). Serum AGE concentration was significantly positively correlated with PVC amount in patients with STEMI (r = 0.416, P < 0.001). Multivariate analysis showed that serum AGE concentration was independently and positively related to frequent PVCs (adjusted hazard ratio, 1.86; 95% CI, 1.09-3.18, P = 0.022). In the animal study, increased glucose-regulated protein 78 (GRP78) expression, protein kinase RNA-like ER kinase (PERK) phosphorylation, CaN enzymatic activity, FKBP12.6-RyR2 disassociation, RyR2 channel opening, and endoplasmic reticulum (ER) calcium releasing were found in diabetic MI animals, which were attenuated by anti-RAGE antibody treatment. This RAGE blocking also significantly lowered the VA amount in diabetic MI animals. Activation of RAGE-dependent ER stress-mediated PERK/CaN/RyR2 signaling participated in post-MI VAs in diabetes.NEW & NOTEWORTHY In this study, we proposed a possible mechanism interpreting the clinical scenario that after myocardial infarction (MI) patients were more vulnerable to ventricular arrhythmias (VAs) when complicated with diabetes. A cohort study revealed that advanced glycation end products (AGEs) accumulated in patients with diabetes and closely associated post-MI VAs. In vivo and in vitro studies indicated that receptor for AGEs (RAGE)-dependent endoplasmic reticulum (ER) stress protein kinase RNA-like ER kinase (PERK) pathway triggered VAs, via ER calcium releasing, through calcineurin/RyR2 mechanism.

TMEM16A channel upregulation in arterial smooth muscle cells produces vasoconstriction during diabetes

The pathological involvement of anion channels in vascular dysfunction that occurs during type 2 diabetes (T2D) is unclear. Here, we tested the hypothesis that TMEM16A, a calcium-activated chloride (Cl-) channel, contributes to modifications in arterial contractility during T2D. Our data indicate that T2D increased TMEM16A mRNA in arterial smooth muscle cells and total and surface TMEM16A protein in resistance-size cerebral and hindlimb arteries of mice. To examine vascular cell types in which TMEM16A protein increased and the functional consequences of TMEM16A upregulation during T2D, we generated tamoxifen-inducible, smooth muscle cell-specific TMEM16A knockout (TMEM16A smKO) mice. T2D increased both TMEM16A protein and Cl- current density in arterial smooth muscle cells of control (TMEM16Afl/fl) mice. In contrast, T2D did not alter arterial TMEM16A protein or Cl- current density in smooth muscle cells of TMEM16A smKO mice. Intravascular pressure stimulated greater vasoconstriction (myogenic tone) in the arteries of T2D TMEM16Afl/fl mice than in the arteries of nondiabetic TMEM16Afl/fl mice. This elevation in myogenic tone in response to T2D was abolished in the arteries of T2D TMEM16A smKO mice. T2D also reduced Akt2 protein and activity in the arteries of T2D mice. siRNA-mediated knockdown of Akt2, but not Akt1, increased arterial TMEM16A protein in nondiabetic mice. In summary, data indicate that T2D is associated with an increase in TMEM16A expression and currents in arterial smooth muscle cells that produces vasoconstriction. Data also suggest that a reduction in Akt2 function drives these pathological alterations during T2D.NEW & NOTEWORTHY We investigated the involvement of TMEM16A channels in vascular dysfunction during type 2 diabetes (T2D). TMEM16A message, protein, and currents were higher in smooth muscle cells of resistance-size arteries during T2D. Pressure stimulated greater vasoconstriction in the arteries of T2D mice that was abolished in the arteries of TMEM16A smKO mice. Akt2 protein and activity were both lower in T2D arteries, and Akt2 knockdown elevated TMEM16A protein. We propose that a decrease in Akt2 function stimulates TMEM16A expression in arterial smooth muscle cells, leading to vasoconstriction during T2D.

Skin AGEs and diabetic neuropathy

Advanced glycation end-products (AGEs) are heterogeneous molecules produced by the non-enzymatic glycation of proteins, lipids, or nucleic acids during hyperglycaemia. Accumulation of AGEs in the peripheral nerves has recently been proposed as an additional risk factor for the development of diabetic neuropathy (DN). The gold standard for measurement of tissue-bound AGEs is tissue biopsy. However, their assessment with the newer, fast and simple method of skin autofluorescence (sAF) has recently gained special interest by virtue of its non-invasive, highly reproducible nature and its acceptable correlation with the reference method of skin biopsy. Accumulation of tissue AGEs evaluated by sAF has been shown to independently correlate with DN. Importantly, increasing evidence underscores their potential value as early biomarkers of the latter. Further important associations include diabetic nephropathy, diabetic retinopathy and cardiovascular autonomic neuropathy. However, the value of the implementation of screening with skin AGEs for DN remains unclear. The aim of the present review is to critically summarise current evidence on the association between skin AGEs and diabetic microvascular complications, with a particular emphasis on diabetic neuropathy, and to note the most important limitations of existing knowledge. Longer follow-up studies are also highly anticipated to clarify its role and provide data on patient selection and cost-effectiveness.

Epigenetic Mechanisms in Diabetic Vascular Complications and Metabolic Memory: The 2020 Edwin Bierman Award Lecture

Macrovascular complications such as atherosclerosis, myocardial infarction and stroke, and microvascular complications such as nephropathy, retinopathy, and neuropathy are the major causes of increased morbidity and mortality in both type 1 and type 2 diabetes. Increased inflammation, oxidative stress, and fibrosis are common features in most diabetes complications. Although extensive studies have examined the biochemical pathways leading to the expression of inflammatory, profibrotic, and other pathological genes, as well as genetic factors related to diabetes and associated complications, much less is known about the contribution of epigenetic changes that occur without alterations in the DNA sequence. Environmental factors, lifestyles, and improper diet implicated in diabetes can affect epigenetic states. Epigenetic modifications, including DNA methylation and histone modifications, can alter gene transcription in response to environmental stimuli and cooperate with noncoding RNAs. These epigenetic modifications have been observed in various target cells under diabetic conditions. Moreover, epigenetics has also been implicated in the phenomenon of metabolic memory observed in clinic trials and animal studies, in which prior episodes of poor glycemic control can confer continued risk of complications despite subsequent glucose normalization. Epigenome-wide association studies in cohorts with diabetes are uncovering epigenotype variations that provide new insights into diabetic vascular complications. Here, I discuss the role of epigenetics and noncoding RNAs in diabetes complications and metabolic memory, and their translation potential to serve as biomarkers and drug targets to improve clinical management of diabetic vascular complications.

Quercetin Attenuated Myeloperoxidase-Dependent HOCl Generation and Endothelial Dysfunction in Diabetic Vasculature

Myeloperoxidase (MPO)-dependent hypochlorous acid (HOCl) generation plays crucial roles in diabetic vascular complications. As a natural polyphenol, quercetin has antioxidant properties in various diabetic models. Herein, we investigated the therapeutic mechanism for quercetin on MPO-mediated HOCl generation and endothelial dysfunction in diabetic vasculature. In vitro, the presence of MPO could amplify high glucose-induced endothelial dysfunction which was significantly inhibited by the NADPH oxidase inhibitor, HOCl or H₂O₂ scavengers, revealing the contribution of MPO/H₂O₂/HOCl to vascular endothelial injury. Furthermore, quercetin effectively inhibited MPO/high glucose-mediated HOCl generation and cytotoxicity to vascular endothelial cells. The inhibitive effect on MPO activity was related to the fact that quercetin reduced high glucose-induced H₂O₂ generation in endothelial cells and directly acted as a competitive substrate for MPO, thus limiting MPO/H₂O₂-dependent HOCl production. Moreover, quercetin could attenuate HOCl-caused endothelial dysfunction in endothelial cells and isolated aortas. In vivo, dietary quercetin significantly inhibited aortic endothelial dysfunction in diabetic mice, while this compound simultaneously suppressed vascular MPO expression and activity. Therefore, it was demonstrated herein that quercetin inhibited endothelial injury in diabetic vasculature via suppression of MPO/high glucose-dependent HOCl formation.

NRF2-Related Epigenetic Modifications in Cardiac and Vascular Complications of Diabetes Mellitus

Diabetes mellitus (DM) is a highly prevalent chronic disease that is accompanied with serious complications, especially cardiac and vascular complications. Thus, there is an urgent need to identify new strategies to treat diabetic cardiac and vascular complications. Nuclear factor erythroid 2-related factor 2 (NRF2) has been verified as a crucial target for the prevention and treatment of diabetic complications. The function of NRF2 in the treatment of diabetic complications has been widely reported, but the role of NRF2-related epigenetic modifications remains unclear. The purpose of this review is to summarize the recent advances in targeting NRF2-related epigenetic modifications in the treatment of cardiac and vascular complications associated with DM. We also discuss agonists that could potentially regulate NRF2-associated epigenetic mechanisms. This review provides a better understanding of strategies to target NRF2 to protect against DM-related cardiac and vascular complications.

Epidemiological Research Advances in Vascular Calcification in Diabetes

Vascular calcification is the transformation of arterial wall mesenchymal cells, particularly smooth muscle cells (SMCs), into osteoblast phenotypes by various pathological factors. Additionally, vascular transformation mediates the abnormal deposition of calcium salts in the vascular wall, such as intimal and media calcification. Various pathological types have been described, such as calcification and valve calcification. The incidence of vascular calcification in patients with diabetes is much higher than that in nondiabetic patients, representing a critical cause of cardiovascular events in patients with diabetes. Because basic research on the clinical transformation of vascular calcification has yet to be conducted, this study systematically expounds on the risk factors for vascular calcification, vascular bed differences, sex differences, ethnic differences, diagnosis, severity assessments, and treatments to facilitate the identification of a new entry point for basic research and subsequent clinical transformation regarding vascular calcification and corresponding clinical evaluation strategies.

Macrovascular Protecting Effects of Berberine through Anti-inflammation and Intervention of BKCa in Type 2 Diabetes Mellitus Rats

OBJECTIVE

The aim of this study was to examine the effect of berberine on diabetes mellitus in vivo and in vitro, and elucidate the underlying mechanisms.

METHODS

Rat models of type 2 diabetes mellitus (T2DM) were established and were treated with berberine. Pathological changes in the thoracic aorta, and inflammatory factor and adiponectin levels were investigated. Vascular smooth muscle cells (VSMCs) of the thoracic aorta were cultured and treated with berberine. Cellular proliferation, migration, and inflammatory factor levels were investigated. Responses of vascular rings to phenylephrine (PE) and sodium nitroprusside (SNP) after berberine intervention and the changes of relaxation responses to SNP after adding Iberiotoxin (IbTX) were investigated.

RESULTS

Berberine ameliorated the pathological status of the thoracic aorta in the T2DM rats. Berberine significantly inhibited the C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) production, and increased the adiponectin level compared with the model group. Compared with the model group, berberine inhibited the proliferation and migration of VSMCs in vitro, and reduced tumor growth factor-β1 (TGF-β1), IL-6, and TNF-α levels. Furthermore, the contraction of thoracic aorta to PE was reduced, while the relaxation response of thoracic aorta to SNP was increased, after the berberine intervention in the T2DM rats. The relaxation response of thoracic aorta to SNP in the model and berberine groups decreased after the IbTX treatment.

CONCLUSION

Protective effects of berberine against macrovascular complications induced by diabetes mellitus may be attributed to inhibiting of the inflammation and intervening of the calcium- activated potassium (BKCa).

Exosomes: Biomarkers and Therapeutic Targets of Diabetic Vascular Complications

Diabetic vascular complications (DVC) including macrovascular and microvascular lesions, have a significant impact on public health, and lead to increased patient mortality. Disordered intercellular cascades play a vital role in diabetic systemic vasculopathy. Exosomes participate in the abnormal signal transduction of local vascular cells and mediate the transmission of metabolic disorder signal molecules in distant organs and cells through the blood circulation. They can store different signaling molecules in the membrane structure and release them into the blood, urine, and tears. In recent years, the carrier value and therapeutic effect of exosomes derived from stem cells have garnered attention. Exosomes are not only a promising biomarker but also a potential target and tool for the treatment of DVC. This review explored changes in the production process of exosomes in the diabetic microenvironment and exosomes' early warning role in DVC from different systems and their pathological processes. On the basis of these findings, we discussed the future direction of exosomes in the treatment of DVC, and the current limitations of exosomes in DVC research.

Characterization of lncRNA and mRNA profiles in rats with diabetic macroangiopathy

Diabetic macroangiopathy is part of the most common serious complications of diabetes. Previous studies indicate that lncRNAs involved in the process of diabetes and another vascular disease. However, their detailed mechanism of the lncRNAs involved in diabetic macroangiopathy has not been well characterized. In the present study, we generated rat models of diabetic macroangiopathy induced by High fat of 16weeks. A total of 15 GK rats were constructed as a test group, along with 15 Wistar rats set as control group, and thoracic aorta tissue from each group was collected. Whole genomic RNA sequencing was performed on thoracic aorta tissue; 3223 novel lncRNAs and 20367 annotated lncRNAs were indemnified in thoracic aorta samples, and 864 lncRNAs were expressed differently in the test and control groups. Gene ontology term enrichment showed the apparent enrichment of inflammatory response and cell apoptosis, which consistent with the results of H&E Staining, TUNEL Assay, and ELISA; Extensive literature reveals inflammatory response and cell apoptosis play an important role in the process of diabetic macroangiopathy. The results of the present study indicated that lncRNAs, especially Nrep. bSep08, Col5a1, aSep0, soygee.aSep08-unspliced, NONRATT013247.2, votar.aSep08-unspliced, etc, both participate in and mediate the process of inflammatory response, cell apoptosis. What’s more. Our research provides further insights into understanding of the basic molecular mechanisms underlying diabetic macroangiopathy.

Salvia miltiorrhiza bunge exerts anti-oxidative effects through inhibiting KLF10 expression in vascular smooth muscle cells exposed to high glucose

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicinal herb Salvia miltiorrhiza Bunge(Danshen) and its components have been widely used to treat cardiovascular diseases for hundreds of years in China, including hypertension, diabetes, atherosclerosis, and chronic heart failure. Salvia miltiorrhiza injection (SMI), an aqueous extracts of Salvia miltiorrhiza Bunge, is one of most widely used traditional Chinese medicine injections. SMI is widely used in the treatment of diabetic vascular complications, However, the mechanisms remain to be defined.

AIM OF THE STUDY

To investigate protective mechanism of Salvia miltiorrhiza Bunge against ROS generation in VSMCs of diabetic mice and patients.

MATERIALS AND METHODS

Salvia miltiorrhiza injection (hereinafter referred to as SMI, 1.5 g mL^-1), which was approved by the State Food and Drug Administration (approval number: Z32020161), was obtained from Shenlong Pharmaceutical Co., Ltd. (batch number: 11040314). SMI or vehicle were intraperitoneally administrated to the HFD-fed db/db mice, artery was harvested after 24weeks later. qRT-PCR and Western blot analysis were used to detect the expression of KLF6, KLF5, KLF4, KLF10, KLF12, and HO-1. DCFH-DA staining detected intracellular ROS production. Loss- and gain-of-function experiments of KLF10 were used to investigate the effect of KLF10 on the expression of HO-1. Dual-luciferase reporter assay evaluated the effect of KLF10 on the activity of the HO-1 promoter.

RESULTS

KLF10 expression and ROS generation are significantly increased in the arteries of HFD-fed db/db mice, VSMCs of diabetic patients, as well as in high glucose-treated VSMCs. KLF10 overexpression suppresses, while its knockdown facilitates the expression of heme oxygenase (HO-1) mRNA and protein. Further, Salvia miltiorrhiza injection (SMI) abrogates KLF10 upregulation and reduces ROS generation induced by high glucose in VSMCs. Mechanistically, KLF10 negatively regulates the HO-1 gene transcription via directly binding to its promoter. Accordingly, SMI treatment of VSMCs reduces ROS generation through inhibiting KLF10 expression and thus relieving KLF10 repression of the expression of HO-1 gene, subsequently contributing to upregulation of HO-1.

CONCLUSION

SMI exerts anti-oxidative effects on VSMCs exposed to high glucose through inhibiting KLF10 expression and thus upregulating HO-1.

The effect of vascular complications of diabetes mellitus on human umbilical cord tissue and the number of Wharton Jelly's mesenchymal stem cells

The current study investigated the change in umbilical cord tissue and the number of markers of Wharton's jelly mesenchymal stem cells (WJ-MSC) in pregnant women with gestational diabetes (GDM), with chronic diabetes who developed nephropathy as vascular complication (VC-PGDM), and healthy pregnant women as the control. The umbilical cords (UC) were investigated by the histomorphological method and the number of WJ-MSC were detected by flow-cytometry using the CD90, CD44, CD105, and CD73 markers in Wharton's jelly (WJ) isolated from fresh umbilical cords. The number of positive cells for CD 90, CD44, CD105, and CD73 were found to be elevated in the GDM group, whereas it was significantly diminished in the VC-PGDM group (p = 0.001, p = 0.001, p = 0.001, and p = 0.001). The only histopathological sign in the GDM group were an increased number of pores in the Wharton jelly. Artery wall thickness/cord diamater ratio was increased, which indicates an increase of the artery wall thickness in the VC- PGDM group (p = 0.039 and p = 0.048). The increase in umbilical cord diameter and number of Wharton jelly mesenchymal stem cells in babies of gestational diabetic mothers was considered as an effect of macrosomia seen in babies of mothers with gestational diabetes. Vasculopathy, a long-term complication of diabetes, is known to affect all tissues by causing marked lower perfusion and hypoxia, as well as a decrease in the MSC number in our study.

About 1/3rd of north Indian patients less than 50 years of age with type 2 diabetes have high pulse wave velocity indicating high risk of atherosclerosis

BACKGROUND AND AIMS

Asian Indian patients with type 2 diabetes mellitus (T2DM) have a high cardiovascular risk even at young age. There is a need to assess this increased risk and identify atherosclerosis early so that appropriate measures for risk reduction can be taken. We aimed to study carotid-femoral pulse wave velocity (Cf-PWV), a non-invasive indicator of atherosclerosis, in patients with diabetes below 50 years of age and its correlation with markers of obesity and other cardiovascular risk factors.

METHODS

Patients (n, 299) with T2DM below 50 years of age underwent measurement of Cf-PWV by applanation tonometry. Anthropometric parameters, blood pressure, liver span, glycosylated hemoglobin, serum lipid profile, urinary microalbumin, ankle brachial index and carotid intima media thickness were measured.

RESULTS

Data show that 32.4% of patients had high Cf-PWV, with mean values higher in males than females. On stepwise multiple linear regression analysis, the significant independent determinants of PWV were age, systolic blood pressure, waist circumference, microalbumin and liver span.

CONCLUSION

About one third patients with T2DM less than 50 years of age, in north India have increased arterial stiffness which correlates with blood pressure, abdominal obesity, liver size and microalbumin, indicating increased risk for coronary artery disease.

NMR-based metabolomic analysis for the effects of Huiyang Shengji extract on rat diabetic skin ulcers

ETHNOPHARMACOLOGICAL RELEVANCE

Huiyang Shengji formula (HSF) is a compound Chinese herbal medicine prescription, and has long been used for treating chronic non-healing wounds.

AIM OF THE STUDY

The purpose of this study was to provide new insight into molecular mechanisms of healing effects of the HSF treatments.

MATERIALS AND METHODS

We established a rat diabetic skin ulcer (DSU) model, and assessed healing effects of four HSF treatments on DSUs by calculating wound healing rates and immunohistochemical detection of the expressions of angiogenesis-related factors in the model rats (Mod) relative to normal rats (Nor), including Huiyang extract (HE), Shengji extract (SE), Huiyang Shengji extract (HSE) and HSE associated with acupuncture (Ac-HSE). We then performed NMR-based metabolomic analyses on skin tissues of the Nor, Mod, HSE-treated, Ac-HSE-treated rats to address metabolic mechanisms underlying these effects.

RESULTS

These treatments up-regulated expressions of two angiogenesis-related factors VEGF and CD31, and improved efficacy of healing DSUs, in which HSE and Ac-HSE exhibited the most significant effects. Compared with Mod, HSE and Ac-HSE groups shared four characteristic metabolites (lactate, histidine, succinate and acetate) and four significantly altered metabolic pathways with Nor. Both HSE and Ac-HSE treatments could partly reverse the metabolically disordered pathological state of DSUs to the normal state. They might improve wound healing through promoting glucose metabolism, BCAAs metabolism, and enhancing antioxidant capacity and angiogenesis in DSU tissues. Ac-HSE significantly enhanced wound healing rates compared to HSE, potentially owing to significant capacities of enhancing anti-oxidation and angiogenesis and interfering three more metabolic pathways.

CONCLUSIONS

This work provides a mechanistic understanding of the healing effects of the HSE and Ac-HSE treatments on DSUs, is of benefit to improvements of the HSF treatments for clinically healing chronic non-healing wounds.

Knockout of vascular smooth muscle EGF receptor in a mouse model prevents obesity-induced vascular dysfunction and renal damage in vivo

AIMS/HYPOTHESIS

Obesity causes type 2 diabetes leading to vascular dysfunction and finally renal end-organ damage. Vascular smooth muscle (VSM) EGF receptor (EGFR) modulates vascular wall homeostasis in part via serum response factor (SRF), a major regulator of VSM differentiation and a sensor for glucose. We investigated the role of VSM-EGFR during obesity-induced renovascular dysfunction, as well as EGFR-hyperglycaemia crosstalk.

METHODS

The role of VSM-EGFR during high-fat diet (HFD)-induced type 2 diabetes was investigated in a mouse model with inducible, VSM-specific EGFR-knockout (KO). Various structural and functional variables as well as transcriptome changes, in vivo and ex vivo, were assessed. The impact of hyperglycaemia on EGFR-induced signalling and SRF transcriptional activity and the underlying mechanisms were investigated at the cellular level.

RESULTS

We show that VSM-EGFR mediates obesity/type 2 diabetes-induced vascular dysfunction, remodelling and transcriptome dysregulation preceding renal damage and identify an EGFR-glucose synergism in terms of SRF activation, matrix dysregulation and mitochondrial function. EGFR deletion protects the animals from HFD-induced endothelial dysfunction, creatininaemia and albuminuria. Furthermore, we show that HFD leads to marked changes of the aortic transcriptome in wild-type but not in KO animals, indicative of EGFR-dependent SRF activation, matrix dysregulation and mitochondrial dysfunction, the latter confirmed at the cellular level. Studies at the cellular level revealed that high glucose potentiated EGFR/EGF receptor 2 (ErbB2)-induced stimulation of SRF activity, enhancing the graded signalling responses to EGF, via the EGFR/ErbB2-ROCK-actin-MRTF pathway and promoted mitochondrial dysfunction.

CONCLUSIONS/INTERPRETATION

VSM-EGFR contributes to HFD-induced vascular and subsequent renal alterations. We propose that a potentiated EGFR/ErbB2-ROCK-MRTF-SRF signalling axis and mitochondrial dysfunction underlie the role of EGFR. This advanced working hypothesis will be investigated in mechanistic depth in future studies. VSM-EGFR may be a therapeutic target in cases of type 2 diabetes-induced renovascular disease.

DATA AVAILABILITY

The datasets generated during and/or analysed during the current study are available in: (1) share_it, the data repository of the academic libraries of Saxony-Anhalt ( https://doi.org/10.25673/32049.2 ); and (2) in the gene expression omnibus database with the study identity GSE144838 ( https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE144838 ). Graphical abstract.

Molecular complexities underlying the vascular complications of diabetes mellitus - A comprehensive review

Diabetes is a chronic disease, characterized by hyperglycemia, which refers to the elevated levels of glucose in the blood, due to the inability of the body to produce or use insulin effectively. Chronic hyperglycemia levels lead to macrovascular and microvascular complications. The macrovascular complications consist of peripheral artery disease (PAD), cardiovascular diseases (CVD) and cerebrovascular diseases, while the microvascular complications comprise of diabetic microangiopathy, diabetic nephropathy, diabetic retinopathy and diabetic neuropathy. Vascular endothelial dysfunction plays a crucial role in mediating both macrovascular and microvascular complications under hyperglycemic conditions. In diabetic microvasculature, the intracellular hyperglycemia causes damage to the vascular endothelium through - (i) activation of four biochemical pathways, namely the Polyol pathway, protein kinase C (PKC) pathway, advanced glycation end products (AGE) pathway and hexosamine pathway, all of which commutes glucose and its intermediates leading to overproduction of reactive oxygen species, (ii) dysregulation of growth factors and cytokines, (iii) epigenetic changes which concern the changes in DNA as a response to intracellular changes, and (iv) abnormalities in non-coding RNAs, specifically microRNAs. This review will focus on gaining an understanding of the molecular complexities underlying the vascular complications in diabetes mellitus, to increase our understanding towards the development of new mechanistic therapeutic strategies to prevent or treat diabetes-induced vascular complications.