Improvement of vascular dysfunction by argirein through inhibiting endothelial cell apoptosis associated with ET-1/Nox4 signal pathway in diabetic rats

Ginsenoside Rk1 improves endothelial function in diabetes through activating peroxisome proliferator-activated receptors

Ginsenoside Rk1, one kind of ginsenoside, is a minor ginsenoside found in Panax ginseng and used as traditional Chinese medicine for centuries. It exhibits anti-tumor and anti-aggregation effects. However, little research has been done on its effect on endothelial function. This study investigated whether ginsenoside Rk1 improved endothelial dysfunction in diabetes and the underlying mechanisms in vivo and in vitro. Male C57BL/6 mice were fed with a 12 week high-fat diet (60% kcal % fat), whereas treatment groups were orally administered with ginsenoside Rk1 (10 and 20 mg per kg per day) in the last 4 weeks. Aortas isolated from C57BL/6 mice were induced by high glucose (HG; 30 mM) and co-treated with or without ginsenoside Rk1 (1 and 10 μM) for 48 h ex vivo. Moreover, primary rat aortic endothelial cells (RAECs) were cultured and stimulated by HG (44 mM) to mimic hyperglycemia, with or without the co-treatment of ginsenoside Rk1 (10 μM) for 48 h. Endothelium-dependent relaxations of mouse aortas were damaged with elevated oxidative stress and downregulation of three isoforms of peroxisome proliferator-activated receptors (PPARs), PPAR-α, PPAR-β/δ, and PPAR-γ, as well as endothelial nitric oxide synthase (eNOS) phosphorylation due to HG or high-fat diet stimulation, which also existed in RAECs. However, after the treatment with ginsenoside Rk1, these impairments were all ameliorated significantly. Moreover, the vaso-protective and anti-oxidative effects of ginsenoside Rk1 were abolished by PPAR antagonists (GSK0660, GW9662 or GW6471). In conclusion, this study reveals that ginsenoside Rk1 ameliorates endothelial dysfunction and suppresses oxidative stress in diabetic vasculature through activating the PPAR/eNOS pathway.

A Novel ARNT-Dependent HIF-2α Signaling as a Protective Mechanism for Cardiac Microvascular Barrier Integrity and Heart Function Post-Myocardial Infarction

Myocardial infarction (MI) significantly compromises the integrity of the cardiac microvascular endothelial barrier, leading to enhanced leakage and inflammation that contribute to the progression of heart failure. While HIF2α is highly expressed in cardiac endothelial cells (ECs) under hypoxic conditions, its role in regulating microvascular endothelial barrier function during MI is not well understood. In this study, we utilized mice with a cardiac-specific deletion of HIF2α, generated through an inducible Cre (Cdh5Cre-ERT2) recombinase system. These mice exhibited no apparent phenotype under normal conditions. However, following left anterior descending (LAD) artery ligation-induced MI, they showed increased mortality associated with enhanced cardiac vascular leakage, inflammation, worsened cardiac function, and exacerbated heart remodeling. These outcomes suggest a protective role for endothelial HIF2α in response to cardiac ischemia. Parallel investigations in human cardiac microvascular endothelial cells (CMVECs) revealed that loss of ecHif2α led to diminished endothelial barrier function, characterized by reduced tight-junction protein levels and increased cell death, along with elevated expression of IL6 and other inflammatory markers. These effects were substantially reversed by overexpressing ARNT, a critical dimerization partner for HIF2α during hypoxia. Additionally, ARNT deletion also led to increased CMVEC permeability. Interestingly, ARNT, rather than HIF2α itself, directly binds to the IL6 promoter to suppress IL6 expression. Our findings demonstrate the critical role of endothelial HIF2α in response to MI and identify the HIF2α/ARNT axis as a transcriptional repressor, offering novel insights for developing therapeutic strategies against heart failure following MI.

Mitochondria-associated endoplasmic reticulum membranes as a therapeutic target for cardiovascular diseases

Cardiovascular diseases (CVDs) are currently the leading cause of death worldwide. In 2022, the CVDs contributed to 19.8 million deaths globally, accounting for one-third of all global deaths. With an aging population and changing lifestyles, CVDs pose a major threat to human health. Mitochondria-associated endoplasmic reticulum membranes (MAMs) are communication platforms between cellular organelles and regulate cellular physiological functions, including apoptosis, autophagy, and programmed necrosis. Further research has shown that MAMs play a critical role in the pathogenesis of CVDs, including myocardial ischemia and reperfusion injury, heart failure, pulmonary hypertension, and coronary atherosclerosis. This suggests that MAMs could be an important therapeutic target for managing CVDs. The goal of this study is to summarize the protein complex of MAMs, discuss its role in the pathological mechanisms of CVDs in terms of its functions such as Ca2+ transport, apoptotic signaling, and lipid metabolism, and suggest the possibility of MAMs as a potential therapeutic approach.

Nox4 as a novel therapeutic target for diabetic vascular complications

Diabetic vascular complications can affect both microvascular and macrovascular. Diabetic microvascular complications, such as diabetic nephropathy, diabetic retinopathy, diabetic neuropathy, and diabetic cardiomyopathy, are believed to be caused by oxidative stress. The Nox family of NADPH oxidases is a significant source of reactive oxygen species and plays a crucial role in regulating redox signaling, particularly in response to high glucose and diabetes mellitus. This review aims to provide an overview of the current knowledge about the role of Nox4 and its regulatory mechanisms in diabetic microangiopathies. Especially, the latest novel advances in the upregulation of Nox4 that aggravate various cell types within diabetic kidney disease will be highlighted. Interestingly, this review also presents the mechanisms by which Nox4 regulates diabetic microangiopathy from novel perspectives such as epigenetics. Besides, we emphasize Nox4 as a therapeutic target for treating microvascular complications of diabetes and summarize drugs, inhibitors, and dietary components targeting Nox4 as important therapeutic measures in preventing and treating diabetic microangiopathy. Additionally, this review also sums up the evidence related to Nox4 and diabetic macroangiopathy.

High Glycemia and Soluble Epoxide Hydrolase in Females: Differential Multiomics in Murine Brain Microvasculature

The effect of a high glycemic diet (HGD) on brain microvasculature is a crucial, yet understudied research topic, especially in females. This study aimed to determine the transcriptomic changes in female brain hippocampal microvasculature induced by a HGD and characterize the response to a soluble epoxide hydrolase inhibitor (sEHI) as a mechanism for increased epoxyeicosatrienoic acids (EETs) levels shown to be protective in prior models of brain injury. We fed mice a HGD or a low glycemic diet (LGD), with/without the sEHI (t-AUCB), for 12 weeks. Using microarray, we assessed differentially expressed protein-coding and noncoding genes, functional pathways, and transcription factors from laser-captured hippocampal microvessels. We demonstrated for the first time in females that the HGD had an opposite gene expression profile compared to the LGD and differentially expressed 506 genes, primarily downregulated, with functions related to cell signaling, cell adhesion, cellular metabolism, and neurodegenerative diseases. The sEHI modified the transcriptome of female mice consuming the LGD more than the HGD by modulating genes involved in metabolic pathways that synthesize neuroprotective EETs and associated with a higher EETs/dihydroxyeicosatrienoic acids (DHETs) ratio. Our findings have implications for sEHIs as promising therapeutic targets for the microvascular dysfunction that accompanies vascular dementia.

Natural Activators of Autophagy Increase Maximal Walking Distance and Reduce Oxidative Stress in Patients with Peripheral Artery Disease: A Pilot Study

Trehalose, spermidine, nicotinamide, and polyphenols have been shown to display pro-autophagic and antioxidant properties, eventually reducing cardiovascular and ischemic complications. This study aimed to investigate whether a mixture of these components improves maximal walking distance (MWD) in peripheral artery disease (PAD) patients. Nitrite/nitrate (NOx), endothelin-1, sNOX2-dp, H2O2 production, H2O2 break-down activity (HBA), ATG5 and P62 levels, flow-mediated dilation (FMD), and MWD were evaluated in 20 PAD patients randomly allocated to 10.5 g of mixture or no-treatment in a single-blind study. The above variables were assessed at baseline and 60 days after mixture ingestion. Compared with baseline, mixture intake significantly increased MWD (+91%; p < 0.01) and serum NOx (+96%; p < 0.001), whereas it significantly reduced endothelin-1 levels (−30%, p < 0.01). Moreover, mixture intake led to a remarkable reduction in sNOX2dp (−31%, p < 0.05) and H2O2 (−40%, p < 0.001) and potentiated antioxidant power (+110%, p < 0.001). Finally, mixture ingestion restored autophagy by increasing ATG5 (+43%, p < 0.01) and decreasing P62 (−29%, p < 0.05). No changes in the above-mentioned variables were observed in the no-treatment group. The treatment with a mixture of trehalose, spermidine, nicotinamide, and polyphenols improves MWD in PAD patients, with a mechanism possibly related to NOX2-mediated oxidative stress downregulation and autophagic flux upregulation. Clinical Trial Registration unique identifier: NCT04061070.

Dihydromyricetin protects against high glucose-induced endothelial dysfunction: Role of HIF-1α/ROR2/NF-κB

OBJECTIVES

Dihydromyricetin (DHM), a natural flavonoid isolated from vine tea with anti-inflammatory activity was evaluated for its ability to prevent vascular endothelial dysfunction caused by hyperglycaemia.

METHODS

Vasoconstrictor (phenylephrine-PE) and vasodilator (acetylcholine-ACh) responses were monitored for female rat aorta rings maintained in a bioassay organ bath for 3 h at 37 °C in either low (LG: 10 mM) or high (HG: 40 mM, to mimic hyperglycaemia) glucose-Krebs buffer in the absence or presence of 50 µM DHM. Tissues recovered from the organ bath at 3 h were fixed and analyzed for morphological changes and their expression of eNOS, iNOS, HIF-1α, GLUT1, ROR2 tyrosine kinase, NF-κB, TNF-α, Bax, Bcl2, caspase-3, and forindices of increased oxidative stress.

KEY FINDINGS

HG-incubated tissues showed increased PE-stimulated contractile response and decreased ACh-mediated endothelial vasodilation. DHM prevented both of these changes. Besides, HG incubation increased the immunoreactivity to iNOS, HIF-1α, GLUT1, ROR2, NF-κB, TNF-α, Bax, and active caspase-3, and decreased the expression of eNOS and Bcl2. Hyperglycaemia-like conditions also increased the indices of oxidative/nitrosative stress. These HG-induced changes, which were accompanied by an increase in tissue adventitial thickness and inflammatory cell infiltration, were all prevented by DHM.

CONCLUSION

Our data demonstrate an anti-inflammatory protective action of DHM to preserve vascular function in the setting of hyperglycaemia.

Long Non-Coding RNAs in the Pathogenesis of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is one of the major microvascular complications of diabetes mellitus, with relatively high morbidity and mortality globally but still in short therapeutic options. Over the decades, a large body of data has demonstrated that oxidative stress, inflammatory responses, and hemodynamic disorders might exert critical influence in the initiation and development of DKD, whereas the delicate pathogenesis of DKD remains profoundly elusive. Recently, long non-coding RNAs (lncRNAs), extensively studied in the field of cancer, are attracting increasing attentions on the development of diabetes mellitus and its complications including DKD, diabetic retinopathy, and diabetic cardiomyopathy. In this review, we chiefly focused on abnormal expression and function of lncRNAs in major resident cells (mesangial cell, endothelial cell, podocyte, and tubular epithelial cell) in the kidney, summarized the critical roles of lncRNAs in the pathogenesis of DKD, and elaborated their potential therapeutic significance, in order to advance our knowledge in this field, which might help in future research and clinical treatment for the disease.

Identification of the Antithrombotic Mechanism of Leonurine in Adrenalin Hydrochloride-Induced Thrombosis in Zebrafish via Regulating Oxidative Stress and Coagulation Cascade

Thrombosis is a general pathological phenomenon during severe disturbances to homeostasis, which plays an essential role in cardiovascular and cerebrovascular diseases. Leonurine (LEO), isolated from Leonurus japonicus Houtt, showes a crucial role in anticoagulation and vasodilatation. However, the properties and therapeutic mechanisms of this effect have not yet been systematically elucidated. Therefore, the antithrombotic effect of LEO was investigated in this study. Hematoxylin-Eosin staining was used to detect the thrombosis of zebrafish tail. Fluorescence probe was used to detect the reactive oxygen species. The biochemical indexes related to oxidative stress (lactate dehydrogenase, malondialdehyde, superoxide dismutase and glutathione) and vasodilator factor (endothelin-1 and nitric oxide) were analyzed by specific commercial assay kits. Besides, we detected the expression of related genes (fga, fgb, fgg, pkcα, pkcβ, vwf, f2) and proteins (PI3K, phospho-PI3K, Akt, phospho-Akt, ERK, phospho-ERK FIB) related to the anticoagulation and fibrinolytic system by quantitative reverse transcription and western blot. Beyond that, metabolomic analyses were carried out to identify the expressions of metabolites associated with the anti-thrombosis mechanism of LEO. Our in vivo experimental results showed that LEO could improve the oxidative stress injury, abnormal platelet aggregation and coagulation dysfunction induced by adrenalin hydrochloride. Moreover, LEO restored the modulation of amino acids and inositol metabolites which are reported to alleviate the thrombus formation. Collectively, LEO attenuates adrenalin hydrochloride-induced thrombosis partly via modulating oxidative stress, coagulation cascade and platelet activation and amino acid and inositol metabolites.

Hengshun Aromatic Vinegar Ameliorates Vascular Endothelial Injury via Regulating PKCζ-Mediated Oxidative Stress and Apoptosis

Vascular endothelial injury (VEI) is an early event of atherosclerosis, and reversing endothelial dysfunction has become a new trend in the prevention and treatment of cardiovascular diseases. Hengshun aromatic vinegar (HSAV), a traditional vinegar, has been reported to have many pharmacological activities, but its effect against VEI and the molecular mechanism are still unknown. In this study, effects of HSAV on VEI were evaluated in H₂O₂-induced human umbilical vein endothelial cells (HUVECs) and methionine-induced VEI in rats. Results showed that HSAV significantly increased cell viability, inhibited apoptosis, and reduced the generation of reactive oxygen species (ROS) in H₂O₂-induced HUVECs. Meanwhile, HSAV decreased serum homocysteine (Hcy), endothelin 1 (ET-1), and oxidized low-density lipoprotein (ox-LDL) levels, increased nitric oxide (NO) and endothelin nitric oxide synthase (eNOS) levels, ameliorated pathological changes in rats with VEI induced by methionine. In parallel, HSAV relieved oxidative stress by decreasing malondialdehyde (MDA) level and increasing superoxide dismutase (SOD), glutathione (GSH), and glutathione peroxidase (GSH-Px) levels in rats with VEI. Mechanism studies indicated that HSAV markedly downregulated the expression of protein kinase C zeta (PKCζ), and consequently regulated sirtuin 1 (Sirt1)-mediated oxidative stress signal pathway, and protein inhibitor of activated STATy (PIASy)-mediated apoptosis pathway, leading to the alleviation of oxidative stress and inhibition of apoptosis. These regulative effects of HSAV were further validated by knockdown and overexpression of PKCζ in vitro. In conclusion, HSAV showed protective effect against VEI by inhibiting PKCζ and, thereby, ameliorating oxidative stress and inhibiting apoptosis. This study not only provides guidance for the consumption of vinegar in daily life but also promotes the development of diet supplement for disease prevention.

Clinical effect and changes of ET-1, FMD and NO levels in the treatment of acute cerebral infarction with acanthopanax injection

OBJECTIVE

To explore clinical efficacy of acanthopanax injection for the treatment of acute cerebral infarction and its effect on the changes in endothelin-1 (ET-1), flow-mediated vasodilation (FMD) and nitric oxide (NO) levels.

METHODS

A total of 120 patients with acute cerebral infarction were selected for prospective study. The patients with conventional treatment regimen were the control group while the observation group was treated acanthopanax injection in addition to the treatment given to the control group. Both groups contained 60 patients. After 14 days of treatment, we observed the clinical effects and measured ET-1, NO, FMD, serum C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), National Institute of Health stroke scale (NIHSS), Mini-mental state examination (MMSE) and Montreal Cognitive Assessment (MoCA) in both groups.

RESULTS

The total effective rate of the observation group was higher than that of the control group (P=0.020). The improvement of ET-1, FMD, NO, CRP, TNF-α and IL-6 in the observation group was superior to that of the control group (P<0.05). The scores of NIHSS, MMSE and MoCA in the observation group were better than those of the control group (P<0.05).

CONCLUSION

The treatment of acute cerebral infarction with acanthopanax injection may enhance the clinical efficacy, improve vascular endothelial function, reduce inflammation and nerve damage, and improve cognitive function.

Isoliquiritigenin attenuates inflammation and modulates Nrf2/caspase-3 signalling in STZ-induced aortic injury

OBJECTIVES

The current study provides evidence on the ameliorative impact of Isoliquiritigenin (ISL), a natural bioflavonoid isolated from licorice roots against diabetes mellitus (DM)-induced aortic injury in rats.

METHODS

DM was induced in male Sprague-Dawley rats by single I.P. injection of STZ (50 mg/kg). ISL was administrated daily (20 mg/kg, orally) for 8 wks.

KEY FINDINGS

Diabetic group showed a significant aortic injury with evidence of atherosclerotic lesions development. Daily ISL (20 mg/kg, orally) administration for 8 wks significantly restored aortic oxidative/antioxidative stress homeostasis via modulating NrF-2/Keap-1/HO-1. Moreover, ISL treatment restored aortic levels of IL-10 and dampened aortic levels of IL-6 and TNF-α. Caspase-3 expression significantly declined as well. Further, ISL treatment successfully suppressed aortic endothelin-1 (ET-1) expression and restored NO contents, eNOS immunostaining paralleled with retraction in atherosclerotic lesions development, and lipid deposition with histopathological architectural preservation and restoration of almost normal aortic thickness.

CONCLUSION

ISL can be proposed to be an effective protective therapy to prevent progression of DM-induced vascular injury and to preserve aortic integrity.

NOX4/Src regulates ANP secretion through activating ERK1/2 and Akt/GATA4 signaling in beating rat hypoxic atria

Nicotinamide adenine dinucleotide phosphate oxidases (NOXs) are the major enzymatic source of reactive oxygen species (ROS). NOX2 and NOX4 are expressed in the heart but its role in hypoxia-induced atrial natriuretic peptide (ANP) secretion is unclear. This study investigated the effect of NOX on ANP secretion induced by hypoxia in isolated beating rat atria. The results showed that hypoxia significantly upregulated NOX4 but not NOX2 expression, which was completely abolished by endothelin-1 (ET-1) type A and B receptor antagonists BQ123 (0.3 µM) and BQ788 (0.3 µM). ET-1-upregulated NOX4 expression was also blocked by antagonists of secreted phospholipase A2 (sPLA2; varespladib, 5.0 µM) and cytosolic PLA2 (cPLA2; CAY10650, 120.0 nM), and ET-1-induced cPLA2 expression was inhibited by varespladib under normoxia. Moreover, hypoxia-increased ANP secretion was evidently attenuated by the NOX4 antagonist GLX351322 (35.0 µM) and inhibitor of ROS N-Acetyl-D-cysteine (NAC, 15.0 mM), and hypoxia-increased production of ROS was blocked by GLX351322. In addition, hypoxia markedly upregulated Src expression, which was blocked by ET receptors, NOX4, and ROS antagonists. ET-1-increased Src expression was also inhibited by NAC under normoxia. Furthermore, hypoxia-activated extracellular signal-regulated kinase 1/2 (ERK1/2) and protein kinase B (Akt) were completely abolished by Src inhibitor 1 (1.0 µM), and hypoxia-increased GATA4 was inhibited by the ERK1/2 and Akt antagonists PD98059 (10.0 µM) and LY294002 (10.0 µM), respectively. However, hypoxia-induced ANP secretion was substantially inhibited by Src inhibitor. These results indicate that NOX4/Src modulated by ET-1 regulates ANP secretion by activating ERK1/2 and Akt/GATA4 signaling in isolated beating rat hypoxic atria.

Apocynin ameliorates NADPH oxidase 4 (NOX4) induced oxidative damage in the hypoxic human retinal Müller cells and diabetic rat retina

NADPH oxidase (NOX) is a main producers of reactive oxygen species (ROS) that may contribute to the early pathogenesis of diabetic retinopathy (DR). ROS has harmful effects on endogenous neuro-survival factors brain-derived neurotrophic factor (BDNF) and sirtuin 1 (SIRT1) are necessary for the growth and survival of the retina. The role of NOX isoforms NOX4 in triggering ROS in DR is not clear. Here we determine the protective effects of a plant-derived NOX inhibitor apocynin (APO) on NOX4-induced ROS production which may contribute to the depletion of survival factors BDNF/SIRT1 or cell death in the diabetic retinas. Human retinal Müller glial cells (MGCs) were treated with hypoxia mimetic agent cobalt chloride (CoCl₂) in the absence or presence of APO. Molecular analysis demonstrates that NOX4 is upregulated in CoCl₂-treated MGCs and in the diabetic retinas. Increased NOX4 was accompanied by the downregulation of BDNF/SIRT1 expression or in the activation of apoptotic marker caspase-3. Whereas, APO treatment downregulates NOX4 and subsequently upregulates BDNF/SIRT1 or alleviate caspase-3 expression. Accordingly, in the diabetic retina we found a positive correlation in NOX4 vs ROS (p = 0.025; R² = 0.488) and caspase-3 vs ROS (p = 0.04; R² = 0.428); whereas a negative correlation in BDNF vs ROS (p = 0.009; R² = 0.596) and SIRT1 vs ROS (p = 0.0003; R² = 0.817) respectively. Taken together, NOX4-derived ROS could be a main contributor in downregulating BDNF/SIRT1 expression or in the activation of caspase-3. Whereas, APO treatment may minimize the deleterious effects occurring due to hyperglycemia and/or diabetic mimic hypoxic condition in early pathogenesis of DR.

Glycyrrhizic Acid Modulates Apoptosis through Extrinsic/Intrinsic Pathways and Inhibits Protein Kinase B- and Extracellular Signal-Regulated Kinase-Mediated Metastatic Potential in Hepatocellular Carcinoma In Vitro and In Vivo

A previous study presented that glycyrrhizic acid as the hepatoprotective agent inhibits total parenteral nutrition-associated acute liver injury in rats. However, the anticancer effect and mechanism of glycyrrhizic acid in human hepatocellular carcinoma (HCC) is ambiguous. The purpose of the present study was to investigate the effect of glycyrrhizic acid on apoptosis dysregulation and metastatic potential in HCC in vitro and in vivo. Both SK-Hep1 and Hep3B cells were treated with different concentrations of glycyrrhizic acid for 24 or 48h. SK-Hep1/luc2 tumor-bearing mice were treated with vehicle or glycyrrhizic acid (50mg/kg/day by intraperitoneal injection) for 7 days. Tumor cells growth, apoptotic, and metastatic signaling transduction were evaluated by using MTT assay, digital caliper, bioluminescence imaging (BLI), flow cytometry, western blotting assay, and immunohistochemistry (IHC) staining. The results demonstrated glycyrrhizic acid significantly inhibits tumor cell growth, cell invasion, and expression of AKT (Ser473), extracellular-signal-regulated kinase (ERK), epidermal growth factor receptor (EGFR) phosphorylation, anti-apoptotic and metastatic proteins in HCC in vitro and in vivo. Glycyrrhizic acid also significantly triggered apoptosis and extrinsic/intrinsic apoptotic signaling transduction. In addition, PD98059 (ERK inhibitor) and LY294002 (AKT inhibitor) obviously reduced cell invasion and expression of metastasis-associated proteins. Taken together, these results indicated that glycyrrhizic acid induces apoptosis through extrinsic/intrinsic apoptotic signaling pathways and diminishes EGFR/AKT/ERK-modulated metastatic potential in HCC in vitro and in vivo.

The Effects of Type 2 Diabetes Mellitus on Organ Metabolism and the Immune System

Metabolic abnormalities such as dyslipidemia, hyperinsulinemia, or insulin resistance and obesity play key roles in the induction and progression of type 2 diabetes mellitus (T2DM). The field of immunometabolism implies a bidirectional link between the immune system and metabolism, in which inflammation plays an essential role in the promotion of metabolic abnormalities (e.g., obesity and T2DM), and metabolic factors, in turn, regulate immune cell functions. Obesity as the main inducer of a systemic low-level inflammation is a main susceptibility factor for T2DM. Obesity-related immune cell infiltration, inflammation, and increased oxidative stress promote metabolic impairments in the insulin-sensitive tissues and finally, insulin resistance, organ failure, and premature aging occur. Hyperglycemia and the subsequent inflammation are the main causes of micro- and macroangiopathies in the circulatory system. They also promote the gut microbiota dysbiosis, increased intestinal permeability, and fatty liver disease. The impaired immune system together with metabolic imbalance also increases the susceptibility of patients to several pathogenic agents such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Thus, the need for a proper immunization protocol among such patients is granted. The focus of the current review is to explore metabolic and immunological abnormalities affecting several organs of T2DM patients and explain the mechanisms, whereby diabetic patients become more susceptible to infectious diseases.

(-)-Epigallocatechin-3-Gallate Inhibits eNOS Uncoupling and Alleviates High Glucose-Induced Dysfunction and Apoptosis of Human Umbilical Vein Endothelial Cells by PI3K/AKT/eNOS Pathway

INTRODUCTION

Diabetes can increase the risk of cardiovascular disease. This study aimed to explore the effect of (-)-epigallocatechin-3-gallate (EGCG) on high glucose (HG)-induced dysfunction and apoptosis of vascular endothelial cells.

MATERIALS AND METHODS

The viability of human umbilical vein endothelial cells (HUVECs) treated with different concentrations and times of EGCG was detected by CCK-8 assay. The expression levels of ROS, NO and BH4 in HUVECs after treatment were detected by respective ELISA kits. The expression of p-eNOS, eNOS, NOX4, bcl2, bax, cleaved-caspase3, caspase3, p-PI3K, p-AKT, PI3K and AKT in HUVECs was detected by Western blot analysis. The apoptosis of HUVECs after treatment was analyzed by TUNEL assay.

RESULTS

The viability of HUVECs was not obviously changed when treated with different concentrations and times of EGCG. The expression of ROS, NOX4 and eNOS (monomer) was increased, while the expression of NO, p-eNOS, eNOS, BH4 and eNOS (dimer) was decreased in HUVECs of HG group. EGCG could gradually reverse the effect of high glucose on HG-treated HUVECs from 10 μM to 50 μM. The apoptosis of HUVECs was also increased in HG group and EGCG decreased the apoptosis of HUVECs. PI3K/AKT signaling pathway was suppressed in HG-treated HUVECs while activated by EGCG treatment. When the PI3K/AKT signaling pathway was inhibited by LY294002 (AKT inhibitor), the protective effect of EGCG on HG-treated HUVECs was weakened.

CONCLUSION

EGCG could inhibit eNOS uncoupling and alleviate endothelial dysfunction and apoptosis of HG-treated HUVECs by activating the PI3K/AKT/eNOS pathway.

Retinal Physiology and Circulation: Effect of Diabetes

In this article, we present a discussion of diabetes and its complications, including the macrovascular and microvascular effects, with the latter of consequence to the retina. We will discuss the anatomy and physiology of the retina, including aspects of metabolism and mechanisms of oxygenation, with the latter accomplished via a combination of the retinal and choroidal blood circulations. Both of these vasculatures are altered in diabetes, with the retinal circulation intimately involved in the pathology of diabetic retinopathy. The later stages of diabetic retinopathy involve poorly controlled angiogenesis that is of great concern, but in our discussion, we will focus more on several alterations in the retinal circulation occurring earlier in the progression of disease, including reductions in blood flow and a possible redistribution of perfusion that may leave some areas of the retina ischemic and hypoxic. Finally, we include in this article a more recent area of investigation regarding the diabetic retinal vasculature, that is, the alterations to the endothelial surface layer that normally plays a vital role in maintaining physiological functions. © 2020 American Physiological Society. Compr Physiol 10:933-974, 2020.

The protective role of calcitonin gene-related peptide (CGRP) in high-glucose-induced oxidative injury in rat aorta endothelial cells

Endothelial dysfunction is considered to be an initial indicator in diabetes-induced macrovascular complications. Evidence has shown that CGRP is an important neuropeptide active in vascular system, especially in vasorelaxation. This study aimed to investigate the role of CGRP in high-glucose-induced endothelial dysfunction in rat aorta endothelial cells (RAECs). Quantitative-real time PCR and western blots were used to determine the efficiency of overexpression and interference of CGRP. After incubation with normal glucose (5.5 mM) or high glucose (33 mM), the cell viability and cell apoptosis were tested. Afterwards, the Nitric Oxide (NO) production, the mRNA expression of inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS) and angiotensin II (Ang II) and the level of reactive oxygen species (ROS) were determined. The involvement of ERK1/2-NOX4 was determined through western blots and the translocation of p47phox was also observed via cell immunofluorescence. CGRP alleviated the high-glucose-induced cell apoptosis while CGRP did not have an obvious impact on cell viability. Meanwhile, CGRP increased the NO production as well as the eNOS mRNA expression and reversely decreased the stimulated expression of iNOS and Ang II by high glucose. In addition, CGRP attenuated the high-glucose-stimulated intracellular ROS production by ERK1/2-NOX4 and the translocation of p47phox. These results indicated the protective role of CGRP in high-glucose-induced oxidative injury in RAECs possibly through inhibiting ERK1/2-NOX4. Our findings might help to further understand the potential role and possible mechanism of CGRP in endothelial dysfunction caused by high glucose.

Engulfment and cell motility protein 1 potentiates diabetic cardiomyopathy via Rac-dependent and Rac-independent ROS production

Engulfment and cell motility protein 1 (ELMO1) is part of a guanine nucleotide exchange factor for Ras-related C3 botulinum toxin substrate (Rac), and ELMO1 polymorphisms were identified to be associated with diabetic nephropathy in genome-wide association studies. We generated a set of Akita Ins2C96Y diabetic mice having 5 graded cardiac mRNA levels of ELMO1 from 30% to 200% of normal and found that severe dilated cardiomyopathy develops in ELMO1-hypermorphic mice independent of renal function at age 16 weeks, whereas ELMO1-hypomorphic mice were completely protected. As ELMO1 expression increased, reactive oxygen species indicators, dissociation of the intercalated disc, mitochondrial fragmentation/dysfunction, cleaved caspase-3 levels, and actin polymerization increased in hearts from Akita mice. Cardiomyocyte-specific overexpression in otherwise ELMO1-hypomorphic Akita mice was sufficient to promote cardiomyopathy. Cardiac Rac1 activity was positively correlated with the ELMO1 levels, and oral administration of a pan-Rac inhibitor, EHT1864, partially mitigated cardiomyopathy of the ELMO1 hypermorphs. Disrupting Nox4, a Rac-independent NADPH oxidase, also partially mitigated it. In contrast, a pan-NADPH oxidase inhibitor, VAS3947, markedly prevented cardiomyopathy. Our data demonstrate that in diabetes mellitus ELMO1 is the "rate-limiting" factor of reactive oxygen species production via both Rac-dependent and Rac-independent NADPH oxidases, which in turn trigger cellular signaling cascades toward cardiomyopathy.

Long non-coding RNA H19, a negative regulator of microRNA-148b-3p, participates in hypoxia stress in human hepatic sinusoidal endothelial cells via NOX4 and eNOS/NO signaling

This study aimed at the participation of lncRNA H19, endothelial NADPH oxidases (NOX4) and miR-148b-3p in hypoxia stress in human hepatic sinusoidal endothelial cells (HHSEC), and clarifying the relationship among them. The expression of lnc H19, NOX4 and miR-148b-3p in cirrhotic patients and hypoxic HHSEC were measured by RT-PCR. The nitric oxide and hydrogen peroxide content in HHSEC were determined using ultraviolet chromatometry. The protein levels of NOX4, endothelial NOS (eNOS) and phosphorylated eNOS (p-eNOS) were measured via western blotting. The interaction between NOX4 promoter and lnc H19/miR-148b-3p was measured by dual-luciferase reporter gene detection system. The present results indicated that the expressions of NOX4 mRNA and lnc H19 were increased but miR-148b-3p was decreased in both cirrhotic patients and hypoxic HHSEC. Further, hypoxia induced the up-regulation of hydrogen peroxide and the down-regulation of eNOS/NO signaling in HHSEC. And these symptoms were ameliorated by lnc H19 shRNA and miR-148b-3p mimics. But the beneficial effects of lnc H19 shRNA and miR-148b-3p mimics were further abolished by miR-148b-3p inhibitor and NOX4 over-expression, respectively. In addition, NOX4 was a direct, negatively regulated target of miR-148b-3p, and miR-148b-3p was negatively regulated by lnc H19. Collectively, lnc H19 is a negatively regulator of microRNA-148b-3p, and participate in hypoxia stress in HHSEC via positively regulating NOX4 and negatively regulating eNOS/NO signaling.

Fluoxetine Induces Apoptosis through Extrinsic/Intrinsic Pathways and Inhibits ERK/NF-κB-Modulated Anti-Apoptotic and Invasive Potential in Hepatocellular Carcinoma Cells In Vitro

The aim of the present study was to verify the effects of fluoxetine on dysregulation of apoptosis and invasive potential in human hepatocellular carcinoma (HCC) SK-Hep1 and Hep3B cells. Cells were treated with different concentrations of fluoxetine for different times. MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assays were used for testing the effects of fluoxetine on cell viability. The regulation of apoptosis signaling, and anti-apoptotic, proliferation, and metastasis-associated proteins after fluoxetine treatment were assayed by flow cytometry and Western blotting assay. The detection of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation after fluoxetine treatment was performed by NF-κB reporter gene assay. The results demonstrated that fluoxetine significantly reduced cell viability, cell migration/invasion, NF-κB, extracellular signal-regulated kinases (ERK) activation, and expression of anti-apoptotic (Cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein (C-FLIP), Myeloid cell leukemia-1 (MCL-1), X-Linked inhibitor of apoptosis protein (XAIP), and Survivin), proliferation (Cyclin-D1), angiogenesis (vascular endothelial growth factor (VEGF)), and metastasis-associated proteins (matrix metalloproteinase-9 (MMP-9)). Fluoxetine also significantly induced apoptosis, unregulated extrinsic (activation of first apoptosis signal protein and ligand (Fas/FasL), and caspase-8) and intrinsic (loss of mitochondrial membrane potential (ΔΨm) pathways and increased Bcl-2 homologous antagonist killer (BAK) apoptosis signaling. Taken together, these results demonstrated that fluoxetine induced apoptosis through extrinsic/intrinsic pathways and diminished ERK/NF-κB-modulated anti-apoptotic and invasive potential in HCC cells in vitro.