Endothelial dysfunction: a multifaceted disorder (The Wiggers Award Lecture)

Cerium- and Iron-Oxide-Based Nanozymes in Tissue Engineering and Regenerative Medicine

Nanoparticulate materials displaying enzyme-like properties, so-called nanozymes, are explored as substitutes for natural enzymes in several industrial, energy-related, and biomedical applications. Outstanding high stability, enhanced catalytic activities, low cost, and availability at industrial scale are some of the fascinating features of nanozymes. Furthermore, nanozymes can also be equipped with the unique attributes of nanomaterials such as magnetic or optical properties. Due to the impressive development of nanozymes during the last decade, their potential in the context of tissue engineering and regenerative medicine also started to be explored. To highlight the progress, in this review, we discuss the two most representative nanozymes, namely, cerium- and iron-oxide nanomaterials, since they are the most widely studied. Special focus is placed on their applications ranging from cardioprotection to therapeutic angiogenesis, bone tissue engineering, and wound healing. Finally, current challenges and future directions are discussed.

Reduced endothelial nitric oxide synthase activation contributes to cardiovascular injury during chronic kidney disease progression

Major cardiovascular events are a common complication in patients with chronic kidney disease (CKD). Endothelial dysfunction can contribute to the cardiovascular injury observed in CKD. Here, we used a rat model of acute kidney injury to CKD transition to investigate heart alterations in the pathway activating endothelial nitric oxide synthase (eNOS) and its impact on the cardiac injury observed during CKD progression. Fifty male Wistar rats were subjected to sham surgery ( n = 25) or bilateral renal ischemia-reperfusion (IR-CKD) for 45 min ( n = 25). Rats were studied on a monthly basis up to 5 mo ( n = 5). In another set of sham and IR-CKD rats, l-arginine was administered starting on the third month after renal ischemia. CKD development and cardiac alterations were monitored in all groups. CKD was characterized by a progressive increase in proteinuria and renal dysfunction that was evident after the fifth month of followup. Heart hypertrophy was observed starting on the fourth month after ischemia-reperfusion. There was a significant increase in brain natriuretic peptide levels. In the heart, IR-CKD rats had increased eNOS phosphorylation at threonine 495 and reduced eNOS-heat shock protein-90α interactions. l-Arginine administration prevented the heart alterations observed during CKD and increased eNOS coupling/dimerization and activation. In summary, CKD progression is accompanied by cardiac hypertrophy, fibrosis, oxidative stress, and increased brain natriuretic peptide levels. These alterations were associated with limited eNOS activation in the heart, which may result in reduced nitric oxide bioavailability and contribute to cardiac injury during CKD.

Rhizoma coptidis as a Potential Treatment Agent for Type 2 Diabetes Mellitus and the Underlying Mechanisms: A Review

Diabetes mellitus, especially type 2 diabetes mellitus (T2DM), has become a significant public health burden. Rhizoma coptidis (RC), known as Huang Lian, is widely used for treating diabetes in China. The bioactive compounds of RC, especially alkaloids, have the potential to suppress T2DM-induced lesions, including diabetic vascular dysfunction, diabetic heart disease, diabetic hyperlipidemia, diabetic nephropathy, diabetic encephalopathy, diabetic osteopathy, diabetic enteropathy, and diabetic retinopathy. This review summarizes the effects of RC and its bioactive compounds on T2DM and T2DM complications. Less research has been conducted on non-alkaloid fractions of RC, which may exert synergistic action with alkaloids. Moreover, we summarized the pharmacokinetic properties and structure-activity relationships of RC on T2DM with reference to extant literature and showed clearly that RC has potential therapeutic effect on T2DM.

Nanotherapies for Treatment of Cardiovascular Disease: A Case for Antioxidant Targeted Delivery

Purpose of Review

Cardiovascular disease (CVD) involves a broad range of clinical manifestations resulting from a dysfunctional vascular system. Overproduction of reactive oxygen and nitrogen species are causally implicated in the severity of vascular dysfunction and CVD. Antioxidant therapy is an attractive avenue for treatment of CVD associated pathologies. Implementation of targeted nano-antioxidant therapies has the potential to overcome hurdles associated with systemic delivery of antioxidants. This review examines the currently available options for nanotherapeutic targeting CVD, and explores successful studies showcasing targeted nano-antioxidant therapy.

Recent Findings

Active targeting strategies in the context of CVD heavily focus on immunotargeting to inflammatory markers like cell adhesion molecules, or to exposed extracellular matrix components. Targeted antioxidant nanotherapies have found success in pre-clinical studies.

Summary

This review underscores the potential of targeted nanocarriers as means of finding success translating antioxidant therapies to the clinic, all with a focus on CVD.

Hydrogen sulfide improves endothelial dysfunction in hypertension by activating peroxisome proliferator-activated receptor delta/endothelial nitric oxide synthase signaling

OBJECTIVE

We aimed to elucidate the ameliorative effect of hydrogen sulfide (H2S) on endothelium-dependent relaxation disturbances via peroxisome proliferator-activated receptor delta/endothelial nitric oxide synthase (PPARδ/eNOS) pathway activation in hypertensive patients and rats.

METHODS

Renal arteries were collected from normotensive and hypertensive patients who underwent nephron-sparing surgery. Renal arteries from 37 patients were cultured with or without sodium H2S (NaHS) 50 μmol/l. The rats were randomly divided into four groups: Sham; Sham + NaHS, two kidneys; one clipped (2K1C); and 2K1C + NaHS. Mean arterial pressure was measured by tail-cuff plethysmography. A microvessel recording technique was used to observe the effect of NaHS on endothelium-dependent relaxation. Plasma H2S concentrations were detected using the monobromobimane method. Real-time PCR and western blotting were used to assess mRNA and protein levels of AT1, cystathionine γ-lyase, PPARδ, and phosphor-eNOS. Laser confocal scanning microscopy measured intracellular NO production in human umbilical vein endothelial cells.

RESULTS

NaHS improved endothelial function in hypertensive humans and rats. The 20-week administration of NaHS to 2K1C rats lowered the mean arterial pressure. In human umbilical vein endothelial cells, NaHS improved the AngII-induced production of NO. NaHS upregulated PPARδ expression, increased protein kinase B (Akt) or adenosine monophosphate kinase-activated protein kinase (AMPK) phosphorylation, and enhanced eNOS phosphorylation. A PPARδ agonist could mimic the ameliorative effect of NaHS that was suppressed by PPARδ, AMPK, or Akt inhibition.

CONCLUSION

H2S plays a protective function in renal arterial endothelium in hypertension by activating the PPARδ/PI3K/Akt/eNOS or PPARδ/AMPK/eNOS pathway. H2S may serve as an effective strategy against hypertension.

Pharmacological correction of endothelial dysfunction using ademethionin and taurine

Introduction: Рharmacological correction of endothelial dysfunction is a urgent problem of modern medicine.

Materials and methods: Endothelial dysfunction was simulated in male rats using the e-NOS inhibitor L-NAME (25 mg/kg/day intraperitoneally, for 7 days). Simulation of ADMA-like preeclampsia was performed by intraperitoneal injection of L-NAME to females in the same doses for 7 days (14-20th days of pregnancy). These pathologies were corrected by administering ademethionine in dose 150 mg/kg and taurine at a dose of 260 mg/kg, as well as their combination at the same doses, intragastrically, through an atraumatic probe, once a day.

Results: In the group with use of taurine at a dose of 260 mg/kg the coefficient of endothelial dysfunction decreased to the level of intact animals. Use of ademethionine at a dose of 150 mg/kg and taurine at a dose of 260 mg/kg combined resulted in the most pronounced endothelioprotective effect on the ADMA-like preeclampsia model. The coefficient of endothelial dysfunction decreased more than when using monotherapy of these drugs. Morphological studies of myocardiocytes showed that the combination of ademethionine at a dose of 150 mg/kg and taurine at a dose of 260 mg/kg prevented an increase in the cross-section of cardiomyocytes.

Discussion: Possibly, ademethionine and taurine have an endothelioprotective effect because of their ability to decrease hyperhomocysteinemia.

Conclusion: The investigated drugs showed pronounced endothelioprotective activity and can be recommended for further pre-clinical studies.

Utility of the cold pressor test to predict future cardiovascular events

INTRODUCTION

The cold pressor test (CPT) is a common and extensively validated test, which induces systemic stress involving immersion of an individual's hand in ice water (normally temperature between 0 and 5 degrees Celsius) for a period of time. CPT has been used in various fields, like examining effects of stress on memory, decision-making, pain and cardiovascular health. Areas covered: In terms of cardiovascular health, current research is mainly interested in predicting the occurrence of cardiovascular (CV) events. The objective of this review is to give an overview of the history and methodology of the CPT, and clinical utility in possibly predicting CV events in CAD and other atherosclerotic diseases. Secondly, we will discuss possible future applications of the CPT in clinical care. Expert opinion: An important issue to address is the fact that the physiology of the CPT is not fully understood at this moment. As pointed out multiple mechanisms might be responsible for contributing to either coronary vasodilatation or coronary vasoconstriction. Regarding the physiological mechanism of the CPT and its effect on the measurements of the carotid artery reactivity even less is known.

Factors related to improvement of cerebrovascular reserve after superficial temporal artery to middle cerebral artery anastomosis for patients with atherosclerotic steno-occlusive disease

BACKGROUND

This study aimed to investigate factors related to improvement of hemodynamics and evaluated the usefulness of intraoperative Doppler for predicting postoperative hemodynamics in patients with cerebrovascular atherosclerotic steno-occlusive disease (CASD) of the internal carotid artery (ICA) or middle cerebral artery (MCA) who were treated with extracranial-intracranial (EC-IC) bypass surgery.

METHOD

Forty-eight patients with CASD of the ICA or MCA who were treated by superficial temporal artery to middle cerebral artery bypass with a follow-up longer than 12 months were enrolled. Repeated transient ischemic attack or completed ischemic stroke was observed under optimal medical therapy in all patients. Intraoperative blood flow velocity of the MCA was evaluated by a Doppler flowmeter. Cerebral blood flow and cerebrovascular reserve (CVR) were evaluated using N-isopropyl-[¹²³I] p-iodoamphetamine (IMP) single photon emission computed tomography (SPECT) preoperatively and 3 months after surgery. Imaging and clinical data were retrospectively reviewed.

RESULTS

CVR was significantly increased postoperatively (p = 0.03). One year after the operation, two (4.2%) patients developed cerebral infarction. The change in MCA flow velocity just after anastomosis compared with pre-anastomosis proximal and distal of the anastomosis site was a median of 3.0 and 2.6 times, respectively. However, there was no significant association between changes in intraoperative MCA flow velocity and postoperative CVR. Multivariate analysis showed that the presence of a lower estimated glomerular filtration rate (eGFR) was an independent risk factor for a decrease in CVR (p = 0.036).

CONCLUSIONS

A higher eGFR might have prognostic value for improvement in CVR after EC-IC bypass surgery in patients with CASD and misery perfusion.

Enhancement by Hydrogen Peroxide of Calcium Signals in Endothelial Cells Induced by 5-HT1B and 5-HT2B Receptor Agonists

Hydrogen peroxide, formed in the endothelium, acts as a factor contributing to the relaxation of blood vessels. The reason for this vasodilatory effect could be modulation by H₂O₂ of calcium metabolism, since mobilization of calcium ions in endothelial cells is a trigger of endothelium-dependent relaxation. The aim of this work was to investigate the influence of H₂O₂ on the effects of Ca²⁺-mobilizing agonists in human umbilical vein endothelial cells (HUVEC). We have found that H₂O₂ in concentration range 10-100 μM increases the rise of [Ca²⁺]_i induced by 5-hydroxytryptamine (5-HT) and carbachol and does not affect the calcium signals of ATP, agonist of type 1 protease-activated receptor SFLLRN, histamine and bradykinin. Using specific agonists of 5-HT1B and 5-HT2B receptors CGS12066B and BW723C86, we have demonstrated that H₂O₂ potentiates the effects mediated by these types of 5-HT receptors. Potentiation of the effect of BW723C86 can be produced by the induction of endogenous oxidative stress in HUVEC. We have shown that the activation of 5-HT2B receptor by BW723C86 causes production of reactive oxygen species (ROS). Inhibitor of NADPH oxidases VAS2870 suppressed formation of ROS and partially inhibited [Ca²⁺]_i rise induced by BW723C86. Thus, it can be assumed that vasorelaxation induced by endogenous H₂O₂ in endothelial cells partially occurs due to the potentiation of the agonist-induced calcium signaling.

Targeting transcriptional control of soluble guanylyl cyclase via NOTCH for prevention of cardiovascular disease

Soluble guanylyl cyclase (sGC) is an effector enzyme of nitric oxide (NO). Recent work has unravelled how levels of this enzyme are controlled, and highlighted a role in vascular disease. We provide a timely summary of available knowledge on transcriptional regulation of sGC, including influences from the NOTCH signalling pathway and genetic variants. It is speculated that hypertension-induced repression of sGC starts a vicious circle that can be initiated by periods of stress, diet or genetic factors, and a key tenet is that reduction in sGC further raises blood pressure. The idea that dysregulation of sGC contributes to syndromes caused by defective NOTCH signalling is advanced, and we discuss drug repositioning for vascular disease prevention. The advantage of targeting sGC expression rather than activity is also considered. It is argued that transcriptional inputs on sGC arise from interactions with other cells, the extracellular matrix and microRNAs (miRNAs), and concluded that the promise of sGC as a target for prevention of cardiovascular disease has increased in recent time.

Role of Endothelial Cells in Renal Fibrosis

Renal fibrosis has been regarded as the common pathway of end-stage renal failure. Understanding the fundamental mechanism that leads to renal fibrosis is essential for developing better therapeutic options for chronic kidney diseases. So far, the main abstractions are on the injury of tubular epithelial cells, activation of interstitial cells, expression of chemotactic factor and adhesion molecule, infiltration of inflammatory cells and homeostasis of ECM. However, emerging studies revealed that endothelial cells (ECs) might happen to endothelial-to-mesenchymal transition (EndMT) dependent and/or independent endothelial dysfunction, which were supposed to accelerate renal fibrosis and are identified as new mechanisms for the proliferation of myofibroblasts as well. In this chapter, we are about to interpret the role of ECs in renal fibrosis and analyze the related molecules and pathways of both EndMT and EndMT independent endothelial dysfunction.

Impact of Exercise on Inflammatory Mediators of Metabolic and Vascular Insulin Resistance in Type 2 Diabetes

The development of obesity is cornerstone in the etiology of metabolic and vascular insulin resistance and consequently exacerbates glycemic control. Exercise is an efficacious first-line therapy for type 2 diabetes that improves insulin action through, in part, reducing hormone mediated inflammation. Together, improving the coordination of skeletal muscle metabolism with vascular delivery of glucose will be required for optimizing type 2 diabetes and cardiovascular disease treatment.

Impaired microvascular reactivity in gestational diabetes is associated with altered glycemic parameters

OBJECTIVES

To assess microvascular reactivity and glycemic parameters in GDM compared to age and GA matched controls.

METHODS

This study involved 21 GDM patients and 31 controls. Microvascular reactivity was assessed using LDF and PORH. Microvascular parameters; PORH_max , PORH_peak , and time to peak perfusion (Tp) were recorded after the release of 3 minutes' upper arm occlusion. HOMA-IR was performed to evaluate insulin resistance.

RESULTS

Average age and GA for subjects were 32.9 years and 29.2 weeks. Mean FBG and a 2-hour postprandial for GDM and controls were 4.87 ± 0.71 vs 3.99 ± 0.59 mmol/L; P < 0.001 and 9.50 ± 1.8 vs 5.67 ± 1.0 mmol/L; P < 0.001. Fasting insulin (13.88 ± 18.9 vs 8.37 ± 11.0 μLU/mL; P = 0.031) and HOMA-IR (3.14 ± 4.6 vs 1.52 ± 2.2; P = 0.004) were higher in GDM. Tp was prolonged in GDM (16.27 ± 4.3 vs 13.86 ± 2.1 seconds; P = 0.011). Positive correlations were seen between Tp and FBG and 2-hour postprandial levels.

CONCLUSION

Tp was prolonged in GDM compared to age-matched controls, indicating impaired microvascular reactivity.

Fetal Cerebrovascular Maturation: Effects of Hypoxia

The human cerebral vasculature originates in the fourth week of gestation and continues to expand and diversify well into the first few years of postnatal life. A key feature of this growth is smooth muscle differentiation, whereby smooth muscle cells within cerebral arteries transform from migratory to proliferative to synthetic and finally to contractile phenotypes. These phenotypic transformations can be reversed by pathophysiological perturbations such as hypoxia, which causes loss of contractile capacity in immature cerebral arteries. In turn, loss of contractility affects all whole-brain cerebrovascular responses, including those involved in flow-metabolism coupling, vasodilatory responses to acute hypoxia and hypercapnia, cerebral autoregulation, and reactivity to activation of perivascular nerves. Future strategies to minimize cerebral injury following hypoxia-ischemic insults in the immature brain might benefit by targeting treatments to preserve and promote contractile differentiation in the fetal cerebrovasculature. This could potentially be achieved through inhibition of receptor tyrosine kinase-mediated growth factors, such as vascular endothelial growth factor and platelet-derived growth factor, which are mobilized by hypoxic and ischemic injury and which facilitate contractile dedifferentiation. Interruption of the effects of other vascular mitogens, such as endothelin and angiotensin-II, and even some miRNA species, also could be beneficial. Future experimental work that addresses these possibilities offers promise to improve current clinical management of neonates who have suffered and survived hypoxic, ischemic, asphyxic, or inflammatory cerebrovascular insults.

mTORC2 facilitates endothelial cell senescence by suppressing Nrf2 expression via the Akt/GSK-3β/C/EBPα signaling pathway

Vascular endothelial cell senescence is a leading cause of age-associated and vascular diseases. Mammalian target of rapamycin complex 2 (mTORC2) is a conserved serine/threonine (Ser/Thr) protein kinase that plays an important regulatory role in various cellular processes. However, its impact on endothelial senescence remains controversial. In this study we investigated the role and molecular mechanisms of mTORC2 in endothelial senescence. A replicative senescence model and H₂O₂-induced premature senescence model were established in primary cultured human umbilical vein endothelial cells (HUVECs). In these senescence models, the formation and activation of mTORC2 were significantly increased, evidenced by the increases in binding of Rictor (the essential component of mTORC2) to mTOR, phosphorylation of mTOR at Ser2481 and phosphorylation of Akt (the effector of mTORC2) at Ser473. Knockdown of Rictor or treatment with the Akt inhibitor MK-2206 attenuated senescence-associated β-galactosidase (β-gal) staining and expression of p53 and p21 proteins in the senescent endothelial cells, suggesting that mTORC2/Akt facilitates endothelial senescence. The effect of mTORC2/Akt on endothelial senescence was due to suppression of nuclear factor erythroid 2-related factor 2 (Nrf2) at the transcriptional level, since knockdown of Rictor reversed the reduction of Nrf2 mRNA expression in endothelial senescence. Furthermore, mTORC2 suppressed the expression of Nrf2 via the Akt/GSK-3β/C/EBPα signaling pathway. These results suggest that the mTORC2/Akt/GSK-3β/C/EBPα/Nrf2 signaling pathway is involved in both replicative and inducible endothelial senescence. The deleterious role of mTORC2 in endothelial cell senescence suggests therapeutic strategies (targeting mTORC2) for aging-associated diseases and vascular diseases.

Ethanol extract of Schisandrae chinensis fructus ameliorates the extent of experimentally induced atherosclerosis in rats by increasing antioxidant capacity and improving endothelial dysfunction

CONTEXT

Schisandrae chinensis fructus, the dried ripe fruit of Schisandra chinensis (Turcz.) Baill. (Magnoliaceae) has been used for thousands of years as a traditional Chinese herb, which can attenuate and prevent the development of cardiovascular events.

OBJECTIVE

To evaluate the effects of the ethanol extracts from Schisandrae chinensis fructus fruit (EESC) on experimental atherosclerosis (AS) in rats.

MATERIALS AND METHODS

Treatment with EESC (0.35, 0.7, 1.4 g/kg/d, i.g.) and simvastatin (4 mg/kg/d, i.g.) on AS rats for 3 weeks. Sprague-Dawley rats on normal chow and under water treatment were used as control. The content of schisandrin, schisandrin A and schisandrin B in EESC was detected by HPLC. Aortic pathology changes, serum biochemical indices and nuclear factor E2-related factor 2 (Nrf-2) and heame oxygenase-1 (HO-1) expressions were measured.

RESULTS

Schisandrin, schisandrin A and schisandrin B contents were 291.8, 81.46 and 279.1 mg/g of dry weight, respectively. EESC significantly reduced the aortic plaque area (76.5, 90.5 and 73.9% reduction), regulated the levels of serum lipid (p < 0.05), enhanced the antioxidant enzyme activities (p < 0.01), reduced the malondialdehyde levels (72.5, 69.3, 67.3%), and up-regulated the Nrf-2 and HO-1 expression (p < 0.05). Furthermore, EESC reduced the levels of oxidized-LDL and endothelin-1 and thromboxane B2 but increased that of 6-keto prostaglandin F1α (p < 0.05). Acute toxicity was calculated on mice to be LD₅₀ > 20 g/kg.

CONCLUSIONS

EESC positively affects the treatment of AS in vivo and the findings will provide a reliable theoretical basis for developing novel therapeutics.

Fenofibrate improves vascular endothelial function and contractility in diabetic mice

Fenofibrate, a peroxisome proliferator-activated receptors α (PPARα) agonist, reduces vascular complications of diabetic patients but its protective mechanisms are not fully understood. Here we tested the hypothesis that fenofibrate improves vascular endothelial dysfunction by balancing endothelium-dependent relaxation and contractility of the aorta in diabetes mellitus (DM). In streptozotocin-induced diabetic mice, eight weeks of fenofibrate treatment (100 mg/Kg/d) improved endothelium dependent relaxation in the macro- and microvessels, increased nitric oxide (NO) levels, reduced renal damage markers and effects of the vasoconstrictor prostaglandin. Levels of superoxide dismutase and catalase were both reduced and hydrogen peroxide was increased in vehicle-treated DM, but these changes were reversed by fenofibrate treatment. Vasodilation of the aorta after fenofibrate treatment was reversed by PPARα or AMPKα inhibitors. Western blots showed that fenofibrate treatment elevated PPARα expression, induced liver kinase B1 (LKB1) translocation from the nucleus to the cytoplasm and activated AMP-activated protein kinase-α (AMPKα), thus activating endothelial NO synthase (eNOS). Also, fenofibrate treatment decreased NF-κB p65 and cyclooxygenase 2 proteins in aortas. Finally, incubation with indomethacin in vitro improved aortic contractility in diabetic mice. Overall, our results show that fenofibrate treatment in diabetic mice normalizes endothelial function by balancing vascular reactivity via increasing NO production and suppressing the vasoconstrictor prostaglandin, suggesting mechanism of action of fenofibrate in mediating diabetic vascular complications.

•

Fenofibrate improves diabetic endothelial function is via PPAR/LKB1/AMPK/eNOS signal.

•

Fenofibrate reduces diabetic endothelial contractility is via NF-κB/COX-2 pathway.

•

Diabetes-associated oxidative stress is attenuated by fenofibrate treatment.

Triglyceride to HDL-cholesterol ratio as an independent risk factor for the poor development of coronary collateral circulation in elderly patients with ST-segment elevation myocardial infarction and acute total occlusion

To determine the prognostic role of triglyceride (TG) to high-density lipoprotein cholesterol (HDL) ratio for poorly developed coronary collateral circulation (CCC) in elderly patients with ST-segment elevation myocardial infarction (STEMI) and acute total occlusion (ATO).As a retrospective case-control study, elderly patients (age ≥60 years) with both STEMI and ATO (n = 346) were classified as having either poorly- or well-developed CCC (Rentrop grades 0-1 and 2-3, respectively). The ratio of TG/HDL was calculated according to the detected levels of TG and HDL. The difference of TG/HDL ratio in those 2 groups was compared by Student t test, and multivariate logistic regression analysis indicating occurrence of poorly developed CCC was performed. Receiver operator characteristic curve (ROC) analysis of TG/HDL ratio which determine the optimal cut-off value of TG/HDL ratio was applied.The TG/HDL ratio was significantly higher in patients with poorly developed CCC than in those with well-developed CCC (2.88 ± 2.52 vs 1.81 ± 1.18, P < .001). In multivariate logistic regression analysis, higher TG/HDL ratio (OR 1.789, 95% CI 1 . 346-2.378, P < .001) and the presence of left circumflex branch of coronary artery (LCX) occlusion (OR6.235, 95% CI 2.220-17.510, P = .001) were emerged as independent positive predictors of poor development of CCC, whereas presence of right coronary artery (RCA) occlusion (OR 0.474, 95% CI 0.265-0.850, P = .002) and onset time (OR 0.693, 95% CI 0.620-0.775, P < .001) were found as negative indicators. The optimal cut-off value of TG/HDL ratio was found as 1.58 in ROC analysis, which yielded an area under the curve value of 0.716 (95% CI 0.654-0.778, P < .001) and demonstrated a sensitivity of 80.9% and a specificity of 59.3% for prediction of poorly developed CCC.TG/HDL ratio is an independent risk factor for predicting poor development of CCC in elderly patients with STEMI and ATO.

Endothelial dysfunction and platelet hyperactivity in type 2 diabetes mellitus: molecular insights and therapeutic strategies

The incidence and prevalence of diabetes mellitus is rapidly increasing worldwide at an alarming rate. Type 2 diabetes mellitus (T2DM) is the most prevalent form of diabetes, accounting for approximately 90-95% of the total diabetes cases worldwide. Besides affecting the ability of body to use glucose, it is associated with micro-vascular and macro-vascular complications. Augmented atherosclerosis is documented to be the key factor leading to vascular complications in T2DM patients. The metabolic milieu of T2DM, including insulin resistance, hyperglycemia and release of excess free fatty acids, along with other metabolic abnormalities affects vascular wall by a series of events including endothelial dysfunction, platelet hyperactivity, oxidative stress and low-grade inflammation. Activation of these events further enhances vasoconstriction and promotes thrombus formation, ultimately resulting in the development of atherosclerosis. All these evidences are supported by the clinical trials reporting the importance of endothelial dysfunction and platelet hyperactivity in the pathogenesis of atherosclerotic vascular complications. In this review, an attempt has been made to comprehensively compile updated information available in context of endothelial and platelet dysfunction in T2DM.

Metabolomic analysis of obesity, metabolic syndrome, and type 2 diabetes: amino acid and acylcarnitine levels change along a spectrum of metabolic wellness

Background

Metabolic syndrome (MS) is a construct used to separate “healthy” from “unhealthy” obese patients, and is a major risk factor for type 2 diabetes (T2D) and cardiovascular disease. There is controversy over whether obese “metabolically well” persons have a higher morbidity and mortality than lean counterparts, suggesting that MS criteria do not completely describe physiologic risk factors or consequences of obesity. We hypothesized that metabolomic analysis of plasma would distinguish obese individuals with and without MS and T2D along a spectrum of obesity-associated metabolic derangements, supporting metabolomic analysis as a tool for a more detailed assessment of metabolic wellness than currently used MS criteria.

Methods

Fasting plasma samples from 90 adults were assigned to groups based on BMI and ATP III criteria for MS: (1) lean metabolically well (LMW; n = 24); (2) obese metabolically well (OBMW; n = 26); (3) obese metabolically unwell (OBMUW; n = 20); and (4) obese metabolically unwell with T2D (OBDM; n = 20). Forty-one amino acids/dipeptides, 33 acylcarnitines and 21 ratios were measured. Obesity and T2D effects were analyzed by Wilcoxon rank-sum tests comparing obese nondiabetics vs LMW, and OBDM vs nondiabetics, respectively. Metabolic unwellness was analyzed by Jonckheere-Terpstra trend tests, assuming worsening health from LMW → OBMW → OBMUW. To adjust for multiple comparisons, statistical significance was set at p < 0.005. K-means cluster analysis of aggregated amino acid and acylcarnitine data was also performed.

Results

Analytes and ratios significantly increasing in obesity, T2D, and with worsening health include: branched-chain amino acids (BCAAs), cystine, alpha-aminoadipic acid, phenylalanine, leucine + lysine, and short-chain acylcarnitines/total carnitines. Tyrosine, alanine and propionylcarnitine increase with obesity and metabolic unwellness. Asparagine and the tryptophan/large neutral amino acid ratio decrease with T2D and metabolic unwellness. Malonylcarnitine decreases in obesity and 3-OHbutyrylcarnitine increases in T2D; neither correlates with unwellness. Cluster analysis did not separate subjects into discreet groups based on metabolic wellness.

Discussion

Levels of 15 species and metabolite ratios trend significantly with worsening metabolic health; some are newly recognized. BCAAs, aromatic amino acids, lysine, and its metabolite, alpha-aminoadipate, increase with worsening health. The lysine pathway is distinct from BCAA metabolism, indicating that biochemical derangements associated with MS involve pathways besides those affected by BCAAs. Even those considered “obese, metabolically well” had metabolite levels which significantly trended towards those found in obese diabetics. Overall, this analysis yields a more granular view of metabolic wellness than the sole use of cardiometabolic MS parameters. This, in turn, suggests the possible utility of plasma metabolomic analysis for research and public health applications.

Low but not high frequency of intermittent hypoxia suppresses endothelium-dependent, oxidative stress-mediated contractions in carotid arteries of obese mice

Obstructive sleep apnea is characterized by intermittent hypoxia (IH) during sleep and predisposes to endothelial dysfunction. Obesity is a major risk factor for the occurrence of sleep apnea. The present study compared the functional impact of low- (IH10; 10 hypoxic events/h) and high-frequency (IH60; 60 hypoxic events/h) IH for 4 wk on endothelial function in male C57BL/6 mice with or without high-fat (HF) diet-induced obesity. Mean arterial blood pressure (tail cuff method) was increased in obese mice after IH60 exposure, i.e., HF + IH60 group. The serum levels of the oxidative stress marker malondialdehyde were augmented in lean IH60 and HF groups, with a further increase in HF + IH60 but a reduction in HF + IH10 mice compared with the HF group. Vascular responsiveness was assessed as changes in isometric tension in isolated arteries. Relaxations to the endothelium-dependent vasodilator acetylcholine were impaired in HF + IH60 aortae. Endothelium-dependent contractions (EDC; response to acetylcholine in the presence of the nitric oxide synthase inhibitor l-NAME) in carotid arteries were augmented in the HF group, but this HF-induced augmentation was suppressed by low-frequency IH exposure. The addition of apocynin (antioxidant) reduced EDC in HF and HF + IH60 groups but not in HF + IH10 group. In conclusion, these findings suggest that exposure of obese mice to mild IH exerts preconditioning-like suppression of endothelium-dependent and oxidative stress-mediated contractions. When IH severity increases, this suppression diminishes and endothelial dysfunction accelerates. NEW & NOTEWORTHY The present study demonstrates, for the first time, that low-frequency intermittent hypoxia may exert a preconditioning-like suppression of oxidative stress-induced endothelium-dependent contractions in mice with diet-induced obesity. This relative suppression was diminished as intermittent hypoxia became more severe, and a deleterious effect on endothelial function emerged.

Endothelial function and dysfunction: Impact of metformin

Cardiovascular and metabolic diseases remain the leading cause of morbidity and mortality worldwide. Endothelial dysfunction is a key player in the initiation and progression of cardiovascular and metabolic diseases. Current evidence suggests that the anti-diabetic drug metformin improves insulin resistance and protects against endothelial dysfunction in the vasculature. Hereby, we provide a timely review on the protective effects and molecular mechanisms of metformin in preventing endothelial dysfunction and cardiovascular and metabolic diseases.

Mathematical model of hypertension-induced arterial remodeling: A chemo-mechanical approach

The development of chronic hypertension is a poorly described process involving many chemical and structural changes to the artery. Typically, mathematical models of this disease focus primarily on the mechanical aspects such as arterial geometry, elasticity, and tissue content, or alternatively on the chemical drivers of vasoactivity such as nitric oxide and reactive oxygen species. This paper presents a model that considers the powerful interaction between mechanical and biochemical drivers of hypertension and arterial remodeling. Based on biological processes thought to be involved in the development of hypertension, we have built a system of algebraic, differential, and integral equations. Endothelial dysfunction, which is known to limit vasodilation, is explicitly considered in the model and plays a vital role in the development of chronic hypertension. Numerical solutions to the system are consistent with available experimental data for normal and spontaneously-hypertensive rats.

Curcumin supplementation and motor-cognitive function in healthy middle-aged and older adults

BACKGROUND

Recent studies suggest curcumin is a promising nutraceutical for improving important clinical and physiological markers of healthy aging, including motor and cognitive function.

OBJECTIVE

To determine if curcumin supplementation improves motor and cognitive function in healthy middle-aged and older adults.

METHODS

39 healthy men and postmenopausal women (45-74 yrs) were randomized to 12 weeks of placebo (n = 19) or curcumin supplementation (2000 mg/day Longvida®; n = 20) with motor and cognitive function assessed at week 0 and 12.

RESULTS

Using measures of the NIH Toolbox and other standardized tests, there were no changes in muscle strength and rate of torque development, dexterity, fatigability, mobility, endurance, and balance between the placebo and curcumin groups after 12 weeks (all P > 0.05). Additionally, there were no changes after 12 weeks of placebo and curcumin supplementation in measures of fluid cognitive ability, a cognitive domain that declines with age, including processing speed, executive function, working memory, and episodic memory (all P > 0.3). There were marginal changes in language, a measure of crystallized cognitive ability that is stable with age, following the intervention, wherein reading decoding increased 3% in the curcumin group (post: 2428±35 vs. pre: 2357±34, P = 0.003), but was unchanged in the placebo group (post: 2334±39 vs. pre: 2364±40, P = 0.07).

CONCLUSIONS

Overall, 12 weeks of curcumin supplementation does not improve motor and cognitive functions in healthy middle-aged and older adults. It is possible that curcumin may enhance these functions in groups with greater baseline impairments than those studied here, including adults greater than 75 years of age and/or patients with clinical disorders.

Treatment of hypertension by increasing impaired endothelial TRPV4-KCa2.3 interaction

The currently available antihypertensive agents have undesirable adverse effects due to systemically altering target activity including receptors, channels, and enzymes. These effects, such as loss of potassium ions induced by diuretics, bronchospasm by beta‐blockers, constipation by Ca²⁺ channel blockers, and dry cough by ACEI, lead to non‐compliance with therapies (Moser, 1990). Here, based on new hypertension mechanisms, we explored a new antihypertensive approach. We report that transient receptor potential vanilloid 4 (TRPV4) interacts with Ca²⁺‐activated potassium channel 3 (KCa2.3) in endothelial cells (ECs) from small resistance arteries of normotensive humans, while ECs from hypertensive patients show a reduced interaction between TRPV4 and KCa2.3. Murine hypertension models, induced by high‐salt diet, N(G)‐nitro‐l‐arginine intake, or angiotensin II delivery, showed decreased TRPV4‐KCa2.3 interaction in ECs. Perturbation of the TRPV4‐KCa2.3 interaction in mouse ECs by overexpressing full‐length KCa2.3 or defective KCa2.3 had hypotensive or hypertensive effects, respectively. Next, we developed a small‐molecule drug, JNc‐440, which showed affinity for both TRPV4 and KCa2.3. JNc‐440 significantly strengthened the TRPV4‐KCa2.3 interaction in ECs, enhanced vasodilation, and exerted antihypertensive effects in mice. Importantly, JNc‐440 specifically targeted the impaired TRPV4‐KCa2.3 interaction in ECs but did not systemically activate TRPV4 and KCa2.3. Together, our data highlight the importance of impaired endothelial TRPV4‐KCa2.3 coupling in the progression of hypertension and suggest a novel approach for antihypertensive drug development.

Involvement of the NO/sGC/cGMP/K+ channels pathway in vascular relaxation evoked by two non-quinazoline α1-adrenoceptor antagonists

The aim of this study was to explore the α₁-adrenoceptor-independent mechanisms involved in the vasorelaxant properties of two non-quinazoline α₁-adrenoceptors antagonists (MH-76 and MH-79). Endothelium intact and endothelium denuded rat aorta was contracted with 1 μM phenylephrine to plateau, and the vasodilatory effect of MH-76 and MH-79 was examined in the absence or presence of inhibitors of the different signal transduction pathways. cGMP concetration was measured in rat aorta (enzyme immunoassay kit). In human aortic endothelial cells (HAEC) NO production was examined using a DAF-FM DA fluorescent indicator, whereas in human aortic smooth muscle cells the influence of the title compounds on K⁺ efflux was evaluated. The vasorelaxant effect of MH-76 and MH-79 was attenuated by endothelium removal, N_ω-Nitro-l-arginine methyl ester (L-NAME) and 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) pretreatment to the level characteristic for α₁-adrenoreceptor blocking activity. In addition, the MH-76 and MH-79 induced relaxation was reduced by K⁺ channels blockers. In endothelium intact rat aorta, MH-76 and MH-79 caused an increase in cGMP level, whereas in HAEC they increased NO generation. In contrast, the reference, quinazoline based α₁-antagonist prazosin, did not influence NO production. Our findings suggest that the mechanisms underlying the vasodilatory properties of non-quinazoline based α₁-adrenoceptors antagonists MH-76 and MH-79 involve not only α₁-adrenoceptor blocking activity but also the activation of the endothelial NO-cGMP signalling pathway and the subsequent opening of K⁺ channels. Our studies show that such double mechanism of action is superior to pure α₁-adrenoceptor blockade, and may be considered as a promising alternative for the prevention and treatment of cardiovascular diseases.

Hyperandrogenemia reduces endothelium-derived hyperpolarizing factor-mediated relaxation in mesenteric artery of female rats

Women with polycystic ovary syndrome (PCOS) are often presented with hyperandrogenemia along with vascular dysfunction and elevated blood pressure. In animal models of PCOS, anti-androgen treatment decreased blood pressure, indicating a key role for androgens in the development of hypertension. However, the underlying androgen-mediated mechanism that contributes to increased blood pressure is not known. This study determined whether elevated androgens affect endothelium-derived hyperpolarizing factor (EDHF)-mediated vascular relaxation responses through alteration in function of gap junctional proteins. Female rats were implanted with placebo or dihydrotestosterone (DHT) pellets (7.5 mg, 90-day release). After 12 weeks of DHT exposure, blood pressure was assessed through carotid arterial catheter and endothelium-dependent mesenteric arterial EDHF relaxation using wire myograph. Connexin expression in mesenteric arteries was also examined. Elevated DHT significantly increased mean arterial pressure and decreased endothelium-dependent EDHF-mediated acetylcholine relaxation. Inhibition of Cx40 did not have any effect, while inhibition of Cx37 decreased EDHF relaxation to a similar magnitude in both controls and DHT females. On the other hand, inhibition of Cx43 significantly attenuated EDHF relaxation in mesenteric arteries of controls but not DHT females. Elevated DHT did not alter Cx37 or Cx40, but decreased Cx43 mRNA and protein levels in mesenteric arteries. In vitro exposure of DHT to cultured mesenteric artery smooth muscle cells dose-dependently downregulated Cx43 expression. In conclusion, increased blood pressure in hyperandrogenic females is due, at least in part, to decreased EDHF-mediated vascular relaxation responses. Decreased Cx43 expression and activity may play a role in contributing to androgen-induced decrease in EDHF function.

Hydroxytyrosol Ameliorates Endothelial Function under Inflammatory Conditions by Preventing Mitochondrial Dysfunction

Mitochondria are fundamental organelles producing energy and reactive oxygen species (ROS); their impaired functions play a key role in endothelial dysfunction. Hydroxytyrosol (HT), a well-known olive oil antioxidant, exerts health benefits against vascular diseases by improving endothelial function. However, the HT role in mitochondrial oxidative stress in endothelial dysfunction is not clear yet. To investigate the HT effects on mitochondrial ROS production in the inflamed endothelium, we used an in vitro model of endothelial dysfunction represented by cultured endothelial cells, challenged with phorbol myristate acetate (PMA), an inflammatory, prooxidant, and proangiogenic agent. We found that the pretreatment of endothelial cells with HT (1–30 μmol/L) suppressed inflammatory angiogenesis, a crucial aspect of endothelial dysfunction. The HT inhibitory effect is related to reduced mitochondrial superoxide production and lipid peroxidation and to increased superoxide dismutase activity. HT, in a concentration-dependent manner, improved endothelial mitochondrial function by reverting the PMA-induced reduction of mitochondrial membrane potential, ATP synthesis, and ATP5β expression. In PMA-challenged endothelial cells, HT also promoted mitochondrial biogenesis through increased mitochondrial DNA content and expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha, nuclear respiratory factor-1, and mitochondrial transcription factor A. These results highlight that HT blunts endothelial dysfunction and pathological angiogenesis by ameliorating mitochondrial function, thus suggesting HT as a potential mitochondria-targeting antioxidant in the inflamed endothelium.

The Essential Element Manganese, Oxidative Stress, and Metabolic Diseases: Links and Interactions

Manganese (Mn) is an essential element that is involved in the synthesis and activation of many enzymes and in the regulation of the metabolism of glucose and lipids in humans. In addition, Mn is one of the required components for Mn superoxide dismutase (MnSOD) that is mainly responsible for scavenging reactive oxygen species (ROS) in mitochondrial oxidative stress. Both Mn deficiency and intoxication are associated with adverse metabolic and neuropsychiatric effects. Over the past few decades, the prevalence of metabolic diseases, including type 2 diabetes mellitus (T2MD), obesity, insulin resistance, atherosclerosis, hyperlipidemia, nonalcoholic fatty liver disease (NAFLD), and hepatic steatosis, has increased dramatically. Previous studies have found that ROS generation, oxidative stress, and inflammation are critical for the pathogenesis of metabolic diseases. In addition, deficiency in dietary Mn as well as excessive Mn exposure could increase ROS generation and result in further oxidative stress. However, the relationship between Mn and metabolic diseases is not clear. In this review, we provide insights into the role Mn plays in the prevention and development of metabolic diseases.

Fundamentals on the biochemistry of peroxynitrite and protein tyrosine nitration

In this review we provide an analysis of the biochemistry of peroxynitrite and tyrosine nitration. Peroxynitrite is the product of the diffusion-controlled reaction between superoxide (O2•-) and nitric oxide (•NO). This process is in competition with the enzymatic dismutation of O2•- and the diffusion of •NO across cells and tissues and its reaction with molecular targets (e.g. guanylate cyclase). Understanding the kinetics and compartmentalization of the O2•- / •NO interplay is critical to rationalize the shift of •NO from a physiological mediator to a cytotoxic intermediate. Once formed, peroxynitrite (ONOO- and ONOOH; pKa = 6,8) behaves as a strong one and two-electron oxidant towards a series of biomolecules including transition metal centers and thiols. In addition, peroxynitrite anion can secondarily evolve to secondary radicals either via its fast reaction with CO2 or through proton-catalyzed homolysis. Thus, peroxynitrite can participate in direct (bimolecular) and indirect (through secondary radical intermediates) oxidation reactions; through these processes peroxynitrite can participate as cytotoxic effector molecule against invading pathogens and/or as an endogenous pathogenic mediator. Peroxynitrite can cause protein tyrosine nitration in vitro and in vivo. Indeed, tyrosine nitration is a hallmark of the reactions of •NO-derived oxidants in cells and tissues and serves as a biomarker of oxidative damage. Protein tyrosine nitration can mediate changes in protein structure and function that affect cell homeostasis. Tyrosine nitration in biological systems is a free radical process that can be promoted either by peroxynitrite-derived radicals or by other related •NO-dependent oxidative processes. Recently, mechanisms responsible of tyrosine nitration in hydrophobic biostructures such as membranes and lipoproteins have been assessed and involve the parallel occurrence and connection with lipid peroxidation. Experimental strategies to reveal the proximal oxidizing mechanism during tyrosine nitration in given pathophysiologically-relevant conditions include mapping and identification of the tyrosine nitration sites in specific proteins.

Targeting the Endoplasmic Reticulum Unfolded Protein Response to Counteract the Oxidative Stress-Induced Endothelial Dysfunction

In endothelial cells, the tight control of the redox environment is essential for the maintenance of vascular homeostasis. The imbalance between ROS production and antioxidant response can induce endothelial dysfunction, the initial event of many cardiovascular diseases. Recent studies have revealed that the endoplasmic reticulum could be a new player in the promotion of the pro- or antioxidative pathways and that in such a modulation, the unfolded protein response (UPR) pathways play an essential role. The UPR consists of a set of conserved signalling pathways evolved to restore the proteostasis during protein misfolding within the endoplasmic reticulum. Although the first outcome of the UPR pathways is the promotion of an adaptive response, the persistent activation of UPR leads to increased oxidative stress and cell death. This molecular switch has been correlated to the onset or to the exacerbation of the endothelial dysfunction in cardiovascular diseases. In this review, we highlight the multiple chances of the UPR to induce or ameliorate oxidative disturbances and propose the UPR pathways as a new therapeutic target for the clinical management of endothelial dysfunction.

Mesenteric arteries from stroke-prone spontaneously hypertensive rats exhibit an increase in nitric-oxide-dependent vasorelaxation

The endothelium is crucial for the maintenance of vascular tone by releasing several vasoactive substances, including nitric oxide (NO). Systemic mean arterial pressure is primarily regulated by the resistance vasculature, which has been shown to exhibit increased vascular reactivity, and decreased vasorelaxation during hypertension. Here, we aimed to determine the mechanism for mesenteric artery vasorelaxation of the stroke-prone spontaneously hypertensive rat (SHRSP). We hypothesized that endothelial NO synthase (eNOS) is upregulated in SHRSP vessels, increasing NO production to compensate for the endothelial dysfunction. Concentration-response curves to acetylcholine (ACh) were performed in second-order mesenteric arteries; we observed decreased relaxation responses to ACh (maximum effect elicited by the agonist) as compared with Wistar-Kyoto (WKY) controls. Vessels from SHRSP incubated with N^ω-nitro-l-arginine methyl ester and (or) indomethacin exhibited decreased ACh-mediated relaxation, suggesting a primary role for NO-dependent relaxation. Vessels from SHRSP exhibited a significantly decreased relaxation response with inducible NO synthase (iNOS) inhibition, as compared with WKY vessels. Western blot analysis showed increased total phosphorylated NF-κB, and phosphorylated and total eNOS in SHRSP vessels. Overall, these data suggest a compensatory role for NO by increased eNOS activation. Moreover, we believe that iNOS, although increasing NO bioavailability to compensate for decreased relaxation, leads to a cycle of further endothelial dysfunction in SHRSP mesenteric arteries.

The protease inhibitor E64d improves ox-LDL-induced endothelial dysfunction in human aortic endothelial cells

Oxidized low-density lipoprotein (ox-LDL)-induced endothelial dysfunction in human vascular endothelial cells contributes to the development of atherosclerosis. E64d, a cysteine protease inhibitor, blocks the elastolytic activity of cathepsin essential for vascular matrix remodeling and reduces neurovascular endothelial apoptosis. The objective of this study was to investigate the effects and the underling mechanisms of E64d on ox-LDL-induced endothelial dysfunction in human aortic endothelial cells (HAECs). HAECs were treated with various concentrations of ox-LDL (0–200 mg/L) for 24 h with or without E64d. The results showed that E64d attenuated ox-LDL-induced increase in soluble intercellular adhesion molecule-1 (sICAM-1) concentration and reduction in endothelial nitric oxide synthase (eNOS) expression, prevented ox-LDL-induced reduction in cell viability and migration ability of HAECs. E64d decreased the protein expression of cathepsin B (CTSB), Beclin 1, and microtubule-associated protein light chain 3 (LC3)-II, but not p62. LC3 puncta and autophagosome formation were also reduced by E64d in HAECs. Moreover, E64d decreased the production of MDA and increased the activity of SOD. The results showed that E64d ameliorated ox-LDL-induced endothelial dysfunction in HAECs.

MicroRNA let-7g inhibits angiotensin II-induced endothelial senescence via the LOX-1-independent mechanism

Endothelial senescence leads to cell dysfunction, which in turn eventually results in cardiovascular disease. Identifying factors that regulate endothelial senescence may provide insight into the pathogenesis of aging. Insulin-like growth factor (IGF) signaling has a significant role in the physiology of endothelial cells (ECs). Overactivation of IGF signaling has been implicated in promoting the aging process. Lectin‑like oxidized low‑density lipoprotein (oxLDL) receptor‑1 (LOX‑1) is a scavenger receptor that mediates the internalization of oxLDL into cells. Previous studies by our group have indicated that microRNA let‑7g exerts an anti‑aging effect on ECs and also suppresses LOX-1 expression. Since LOX‑1 also induces the aging process, the present study we explored whether let‑7g still exerts an anti‑aging effect on ECs when LOX‑1 is suppressed. Angiotensin II (Ang II) was used to induce senescence in ECs. It was revealed that Ang II significantly increased the expression of aging markers, including β‑galactosidase, LOX‑1, IGF1 and its receptor IGF1R. On the contrary, Ang II decreased the expression of the anti‑aging gene sirtuin 1 (SIRT1). When LOX‑1 was knocked down by small interfering RNA, let‑7g still dose‑dependently decreased the expression of β‑galactosidase (β‑gal), LOX‑1, IGF1 and IGF1R, and SIRT1 was still upregulated. Using senescence‑associated β‑gal staining, it was confirmed that let‑7g exerts a LOX‑1‑independent anti‑aging effect on ECs. In conclusion, the present study demonstrated that let‑7g has an anti‑aging effect regardless of the presence or absence of LOX-1.

The gut microbiota as a novel regulator of cardiovascular function and disease

The gut microbiome has emerged as a critical regulator of human physiology. Deleterious changes to the composition or number of gut bacteria, commonly referred to as gut dysbiosis, has been linked to the development and progression of numerous diet-related diseases, including cardiovascular disease (CVD). Most CVD risk factors, including aging, obesity, certain dietary patterns, and a sedentary lifestyle, have been shown to induce gut dysbiosis. Dysbiosis is associated with intestinal inflammation and reduced integrity of the gut barrier, which in turn increases circulating levels of bacterial structural components and microbial metabolites that may facilitate the development of CVD. The aim of the current review is to summarize the available data regarding the role of the gut microbiome in regulating CVD function and disease processes. Particular emphasis is placed on nutrition-related alterations in the microbiome, as well as the underlying cellular mechanisms by which the microbiome may alter CVD risk.

Defenders and Challengers of Endothelial Barrier Function

Regulated vascular permeability is an essential feature of normal physiology and its dysfunction is associated with major human diseases ranging from cancer to inflammation and ischemic heart diseases. Integrity of endothelial cells also play a prominent role in the outcome of surgical procedures and organ transplant. Endothelial barrier function and integrity are regulated by a plethora of highly specialized transmembrane receptors, including claudin family proteins, occludin, junctional adhesion molecules (JAMs), vascular endothelial (VE)-cadherin, and the newly identified immunoglobulin (Ig) and proline-rich receptor-1 (IGPR-1) through various distinct mechanisms and signaling. On the other hand, vascular endothelial growth factor (VEGF) and its tyrosine kinase receptor, VEGF receptor-2, play a central role in the destabilization of endothelial barrier function. While claudins and occludin regulate cell-cell junction via recruitment of zonula occludens (ZO), cadherins via catenin proteins, and JAMs via ZO and afadin, IGPR-1 recruits bullous pemphigoid antigen 1 [also called dystonin (DST) and SH3 protein interacting with Nck90/WISH (SH3 protein interacting with Nck)]. Endothelial barrier function is moderated by the function of transmembrane receptors and signaling events that act to defend or destabilize it. Here, I highlight recent advances that have provided new insights into endothelial barrier function and mechanisms involved. Further investigation of these mechanisms could lead to the discovery of novel therapeutic targets for human diseases associated with endothelial dysfunction.

Ergothioneine Antioxidant Function: From Chemistry to Cardiovascular Therapeutic Potential

Ergothioneine (ESH), the betaine of 2-mercapto-L-histidine, is a water-soluble naturally occurring amino acid with antioxidant properties. ESH accumulates in several human and animal tissues up to millimolar concentration through its high affinity transporter, namely the organic cation transporter 1 (OCTN1). ESH, first isolated from the ergot fungus (Claviceps purpurea), is synthesized only by Actinomycetales and non-yeast-like fungi. Plants absorb ESH via symbiotic associations between their roots and soil fungi, whereas mammals acquire it solely from dietary sources. Numerous evidence demonstrated the antioxidant and cytoprotective effects of ESH, including protection against cardiovascular diseases, chronic inflammatory conditions, ultraviolet radiation damages, and neuronal injuries. Although more than a century after its discovery has gone by, our understanding on the in vivo ESH mechanism is limited and this compound still intrigues researchers. However, recent evidence about differences in chemical redox behavior between ESH and alkylthiols, such as cysteine and glutathione, has opened new perspectives on the role of ESH during oxidative damage. In this short review, we discuss the role of ESH in the complex machinery of the cellular antioxidant defense focusing on the current knowledge on its chemical mechanism of action in the protection against cardiovascular disease.

Gallic acid improves endothelium-dependent vasodilatory response to histamine in the mesenteric vascular bed of diabetic rats

BACKGROUND

Endothelial dysfunction is one of the many complications caused by diabetes mellitus. The aim of the present study was to evaluate the effects of gallic acid (GA) on the mesenteric vascular bed (MVB) response to histamine in diabetic rats.

METHODS

Forty male Wistar rats were randomly assigned to a control group, an untreated alloxan-induced diabetic group and three diabetic groups treated with different doses of GA. Six weeks after induction of diabetes and GA treatment, total antioxidant capacity (TAC), malondialdehyde (MDA) concentrations, and the vasodilatory response to histamine of the MVB (measured as changes in perfusion pressure) were determined.

RESULTS

The vasodilatory response to histamine and TAC decreased, whereas MDA increased in the plasma from diabetic rats (P < 0.01). However, in the presence of 3 × 10^-5  mol/L N ^G -nitro-l-arginine methyl ester (a nitric oxide synthase inhibitor) and 1 × 10^-5  mol/L indomethacin (an inhibitor of prostaglandin production), the vasodilatory response of the MVB to histamine was reduced in all groups (P < 0.001). Treatment of diabetic rats with 20 and 40 mg/kg per day GA, but not 10 mg/kg per day GA, increased TAC and decreased MDA concentrations (P < 0.01 and P < 0.001 vs untreated diabetic rats, respectively) and significantly improved the vasodilatory response to histamine (P < 0.05 and P < 0.001, respectively).

CONCLUSION

The results show that, in diabetic rats, the endothelium-dependent vasodilatory response of the MVB to histamine is significantly decreased and depends on both nitric oxide- and prostaglandin-producing pathways and may be mediated by oxidative stress. Treatment with the antioxidant GA restored the vasodilatory response of the MVB to histamine.

The vascular endothelium: A regulator of arterial tone and interface for the immune system

As the primary interface between the blood and various tissues of the body, the vascular endothelium exhibits a diverse range of roles and activities, all of which contribute to the overall health and function of the cardiovascular system. In this focused review, we discuss several key aspects of endothelial function, how this may be compromised and subsequent consequences. Specifically, we examine the dynamic regulation of arterial contractility and distribution of blood flow through the generation of chemical and electrical signaling events that impinge upon vascular smooth muscle. The endothelium can generate a diverse range of vasoactive compounds and signals, most of which act locally to adjust blood flow in a dynamic fashion to match tissue metabolism. Disruption of these vascular signaling processes (e.g. reduced nitric oxide bioavailability) is typically referred to as endothelial dysfunction, which is a recognized risk factor for cardiovascular disease in patients and occurs early in the development and progression of hypertension, atherosclerosis and tissue ischemia. Endothelial dysfunction is also associated with type-2 Diabetes and aging and increased mechanistic knowledge of the cellular changes contributing to these effects may provide important clues for interventional strategies. The endothelium also serves as the initial site of interaction for immune cells entering tissues in response to damage and acts to facilitate the actions of both the innate and acquired immune systems to interact with the vascular wall. In addition to representing the main cell type responsible for the formation of new blood vessels (i.e. angiogenesis) within the vasculature, the endothelium is also emerging as a source of extracellular vesicle or microparticles for the transport of signaling molecules and other cellular materials to nearby, or remote, sites in the body. The characteristics of released microparticles appear to change with the functional status of the endothelium; thus, these microparticles may represent novel biomarkers of endothelial health and more serious cardiovascular disease.

Preconditioning potential of purmorphamine: a hedgehog activator against ischaemic reperfusion injury in ovariectomised rat heart

OBJECTIVE

The present study was been designed to investigate the role and pharmacological potential of hedgehog in oestrogen-deficient rat heart.

METHODS

Oestrogen deficiency was produced in female Wistar rats by the surgical removal of both ovaries and these animals were used four weeks later. Isolated rat heart was subjected to 30 min ischaemia followed by 120 min of reperfusion (I/R). The heart was subjected to pharmacological preconditioning with the hedgehog agonist purmorphamine (1μM) and GDC-0449, a hedgehog antagonist, in the last episode of reperfusion before I/R. Myocardial infarction was assessed in terms of the increase in lactate dehydrogenase (LDH), creatinine kinase-MB (CK-MB), myeloperoxidase (MPO) level and infarct size (triphenyltetrazolium chloride staining). Immunohistochemistry analysis was done for the assessment of tumour necrosis factor (TNF)-α level in cardiac tissue. eNOS expression was estimated by rt-PCR.

RESULTS

Pharmacological preconditioning with purmorphamine significantly attenuated I/R-induced myocardial infarction, TNF-α, MPO level and release of LDH and CK-MB compared to the I/R control group. However, GDC-0449 prevented the ameliorative preconditioning effect of estradiol.

CONCLUSION

It may be concluded that the hedgehog agonist purmorphamine prevents the ovariectomised heart from ischaemic reperfusion injury.

The Lymphatic Vasculature: Its Role in Adipose Metabolism and Obesity

Obesity is a key risk factor for metabolic and cardiovascular diseases, and although we understand the mechanisms regulating weight and energy balance, the causes of some forms of obesity remain enigmatic. Despite the well-established connections between lymphatics and lipids, and the fact that intestinal lacteals play key roles in dietary fat absorption, the function of the lymphatic vasculature in adipose metabolism has only recently been recognized. It is well established that angiogenesis is tightly associated with the outgrowth of adipose tissue, as expanding adipose tissue requires increased nutrient supply from blood vessels. Results supporting a crosstalk between lymphatic vessels and adipose tissue, and linking lymphatic function with metabolic diseases, obesity, and adipose tissue, also started to accumulate in the last years. Here we review our current knowledge of the mechanisms by which defective lymphatics contribute to obesity and fat accumulation in mouse models, as well as our understanding of the lymphatic-adipose tissue relationship.

Teucrium polium-induced Vasorelaxation Mediated by Endothelium-dependent and Endothelium-independent Mechanisms in Isolated Rat Thoracic Aorta

OBJECTIVE

There are some reports on hypotensive and antispasmodic effects of Teucrium polium L. (Lamiaceae) (TP).

SUBJECTS AND METHODS

The activity of different concentrations of TP extract (1, 2, 4 and 8 mg/ml) was evaluated on contractile responses of isolated aorta to potassium chloride (KCl) and phenylephrine (PE).

RESULTS

The cumulative concentrations of the extract induced a concentration-dependent relaxation in the aorta precontracted by PE and KCl. Extract-induced vasorelaxations in denuded aortic rings precontracted by PE and KCl at lower concentrations were considerably less than intact aortic rings, but this effect was significantly more at concentrations of 4 mg/ml for PE-, 4 and 8 mg/ml for KCl-induced contractions. All the extract concentrations (except 1 mg/ml) significantly relaxed PE-induced contraction in the presence of NG-nitro-L-arginine methyl ester. Indomethacin reduced effectively extract-induced vasorelaxation at 1 and 2 mg/ml. The extract reduced PE- and KCl-induced contractions in the presence of cumulative calcium concentrations and after incubation with diltiazem; this vasorelaxant effect of TP was decreased. TP-induced relaxation was inhibited by heparin, ruthenium red, glibenclamide, and tetraethylammonium, but 4-aminopyridine had no effect on TP-induced relaxation.

CONCLUSION

TP extract has vasorelaxant effect on isolated rat thoracic aorta which mediated by endothelium-dependent and endothelium-independent mechanisms. The relaxation mainly was mediated by inhibition of calcium influx in vascular smooth muscle cells. It seems that the vasorelaxant effect of extract at lower concentrations was mediated by nitric oxide and prostacyclin.

SUMMARY

The vasodilatory effect of Teucrium polium L. was mediated by several mechanisms. First: Teucrium polium L. inhibited receptor operated ROCC and VDCC. Second: Teucrium polium L. also inhibited KATP and KCa channels. Third: Teucrium polium L. blocked IP3 receptor and reduced the release of calcium from intracellular source. Forth: Teucrium polium L. increased the release on NO and PGI2 from endothelial cells. Abbreviations Used: ROCC: Receptor operated calcium channels, VDCC: Voltage dependent calcium channels, PLC: Phospholipase C, IP3: 1,4,5 triphosphate inositol, IP3R: IP3 receptors, SR: sarcoplasmic reticulum, RYR: ryanodine receptors, K+ATP: ATP-sensitive potassium channel, K+Ca: Calcium-activated potassium channel, cAMP: Cyclic adenosine monophosphate, cGMP: Cyclic guanosine monophosphate, PGI2: Prostaglandin I2, NO: Nitric oxide.

Regulation of endothelial hemoglobin alpha expression by Kruppel-like factors

Hemoglobin subunit alpha (HBA) expression in endothelial cells (ECs) has recently been shown to control vascular tone and function. We sought to elucidate the transcriptional regulation of HBA expression in the EC. Gain of KLF2 or KLF4 function studies led to significant induction of HBA in ECs. An opposite effect was observed in ECs isolated from animals with endothelial-specific ablation of Klf2, Klf4 or both. Promoter reporter assays demonstrated that KLF2/KLF4 transactivated the hemoglobin alpha promoter, an effect that was abrogated following mutation of all four putative KLF-binding sites. Fine promoter mutational studies localized three out of four KLF-binding sites (sites 2, 3, and 4) as critical for the transactivation of the HBA promoter by KLF2/KLF4. Chromatin immunoprecipitation studies showed that KLF4 bound to the HBA promoter in ECs. Thus, KLF2 and KLF4 serve as important regulators that promote HBA expression in the endothelium.

Pathophysiology and Management of Acute Respiratory Distress Syndrome in Children

Acute respiratory distress syndrome (ARDS) is a syndrome of noncardiogenic pulmonary edema and hypoxia that accompanies up to 30% of deaths in pediatric intensive care units. Pediatric ARDS (PARDS) is diagnosed by the presence of hypoxia, defined by oxygenation index or Pao₂/Fio₂ ratio cutoffs, and new chest infiltrate occurring within 7 days of a known insult. Hallmarks of ARDS include hypoxemia and decreased lung compliance, increased work of breathing, and impaired gas exchange. Mortality is often accompanied by multiple organ failure. Although many modalities to treat PARDS have been investigated, supportive therapies and lung protective ventilator support remain the mainstay.

l-arginine and l-NMMA for assessing cerebral endothelial dysfunction in ischaemic cerebrovascular disease: A systematic review

Endothelial dysfunction (ED), in particular cerebral ED, may be an essential biomarker for ischaemic cerebrovascular disease. However, there is no consensus on methods to best estimate cerebral ED. In this systematic review, we evaluate the use of l-arginine and N^G -monomethyl-l-arginine (l-NMMA) for assessment of cerebral ED. A systematic search of PubMed, EMBASE and the Cochrane Library was done. We included studies investigating cerebrovascular response to l-arginine or l-NMMA in human subjects with vascular risk factors or ischaemic cerebrovascular disease. Seven studies (315 subjects) were eligible according to inclusion and exclusion criteria. Studies investigated the effect of age (n=2), type 2 diabetes mellitus (DM) (n=1), cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) (n=1), leukoaraiosis (n=1), and prior ischaemic stroke or transient ischaemic attack (TIA) (n=2) on cerebral ED. Most studies applied transcranial Doppler to quantify cerebral ED. Endothelium-dependent vasodilatation (EDV) induced by l-arginine was impaired in elderly and subjects with leukoaraiosis, but enhanced in CADASIL patients. Studies including subjects with prior ischaemic stroke or TIA reported both enhanced and impaired EDV to l-arginine. Responses to l-NMMA deviated between subjects with type 2 DM and the elderly. We found only few studies investigating cerebral endothelial responses to l-arginine and l-NMMA in subjects with vascular risk factors or ischaemic cerebrovascular disease. Inconsistencies in results were most likely due to variations in methods and included subject populations. In order to use cerebral ED as a prognostic marker, further studies are required to evaluate the association to cerebrovascular disease.

The Role of Adenosine A2A Receptor, CYP450s, and PPARs in the Regulation of Vascular Tone

Adenosine is an endogenous mediator involved in a myriad of physiologic functions, including vascular tone regulation. It is also implicated in some pathologic conditions. Four distinct receptor subtypes mediate the effects of adenosine, such as its role in the regulation of the vascular tone. Vascular tone regulation is a complex and continuous process which involves many mechanisms and mediators that are not fully disclosed. The vascular endothelium plays a pivotal role in regulating blood flow to and from all body organs. Also, the vascular endothelium is not merely a physical barrier; it is a complex tissue with numerous functions. Among adenosine receptors, A2A receptor subtype (A2AAR) stands out as the primary receptor responsible for the vasodilatory effects of adenosine. This review focuses on important effectors of the vascular endothelium, including adenosine, adenosine receptors, EETs (epoxyeicosatrienoic acids), HETEs (hydroxyeicosatetraenoic acids), PPARs (peroxisome proliferator-activated receptors), and KATP channels. Given the impact of vascular tone regulation in cardiovascular physiology and pathophysiology, better understanding of the mechanisms affecting it could have a significant potential for developing therapeutic agents for cardiovascular diseases.

Early tranexamic acid administration ameliorates the endotheliopathy of trauma and shock in an in vitro model

BACKGROUND

Systemic vascular endothelial injury is a consequence of trauma (T)/hemorrhagic shock (HS) which results in disturbances of coagulation, inflammation, and endothelial barrier integrity. The effect of T/HS on the endothelium (endotheliopathy of trauma [EoT]) is of intense research interest and may lead to EoT-directed therapies. Administration of tranexamic acid (TXA) in trauma patients is associated with a survival benefit and fewer complications if given early after injury. Mechanisms for this protective effect include the antifibrinolytic and anti-inflammatory effects of TXA. We hypothesized that "early" administration of TXA would abrogate vascular endothelial cell activation and injury after T/HS. This was studied in vitro.

METHODS

Confluent human umbilical vein endothelial cells were exposed to hydrogen peroxide and/or epinephrine to stimulate post-T/HS oxidant exposure and/or sympathoadrenal activation. TXA was added 15 minutes, 60 minutes, or 120 minutes after H2O2 and/or epinephrine challenge. Endothelial cell injury was indexed by cell monolayer permeability, intracellular adhesion molecule expression, soluble thrombomodulin, syndecan release (marker for glycocalyx injury), tissue type plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) and angiopoietin-2/angiopoietin-1 ratio (APO-2/APO-1).

RESULTS

Endothelial activation and injury as indexed by permeability, ICAM expression, soluble thrombomodulin were increased by H2O2 and/or epinephrine exposure. Biomarkers of endothelial coagulation profile (tPA/PAI-1) demonstrated a profibrinolytic profile (increased tPA and tPA/PAI-1 ratio) after challenge by H2O2 and/or epinephrine. Vascular "leakiness" as indexed by APO-2/APO-1 ratio was also evident. The most profound effects were noted with H2O2/epinephrine exposure. TXA administration within 60 minutes of H2O2/epinephrine challenge abolished the adverse effects noted on the endothelial-glycocalyx "double barrier." TXA administration after 60 minutes was not protective.

CONCLUSION

Antifibrinolytic and other protective effects of TXA administration on endothelial injury are time-dependent. This study supports the concept that the clinical efficacy of TXA administration requires "early administration."