Age-related changes in endothelial nitric oxide synthase phosphorylation and nitric oxide dependent vasodilation: evidence for a novel mechanism involving sphingomyelinase and ceramide-activated phosphatase 2A

Ceramides are fuel gauges on the drive to cardiometabolic disease

Ceramides are signals of fatty acid excess that accumulate when a cell's energetic needs have been met and its nutrient storage has reached capacity. As these sphingolipids accrue, they alter the metabolism and survival of cells throughout the body including in the heart, liver, blood vessels, skeletal muscle, brain, and kidney. These ceramide actions elicit the tissue dysfunction that underlies cardiometabolic diseases such as diabetes, coronary artery disease, metabolic-associated steatohepatitis, and heart failure. Here, we review the biosynthesis and degradation pathways that maintain ceramide levels in normal physiology and discuss how the loss of ceramide homeostasis drives cardiometabolic pathologies. We highlight signaling nodes that sense small changes in ceramides and in turn reprogram cellular metabolism and stimulate apoptosis. Finally, we evaluate the emerging therapeutic utility of these unique lipids as biomarkers that forecast disease risk and as targets of ceramide-lowering interventions that ameliorate disease.

Photobiomodulation Inhibits Ischemia-Induced Brain Endothelial Senescence via Endothelial Nitric Oxide Synthase

Recent research suggests that photobiomodulation therapy (PBMT) positively impacts the vascular function associated with various cerebrovascular diseases. Nevertheless, the specific mechanisms by which PBMT improves vascular function remain ambiguous. Since endothelial nitric oxide synthase (eNOS) is crucial in regulating vascular function following cerebral ischemia, we investigated whether eNOS is a key element controlling cerebrovascular function and the senescence of vascular endothelial cells following PBMT treatment. Both rat photothrombotic (PT) stroke and in vitro oxygen-glucose deprivation (OGD)-induced vascular endothelial injury models were utilized. We demonstrated that treatment with PBMT (808 nm, 350 mW/cm2, 2 min/day) for 7 days significantly reduced PT-stroke-induced vascular permeability. Additionally, PBMT inhibited the levels of endothelial senescence markers (senescence green and p21) and antiangiogenic factor (endostatin), while increasing the phospho-eNOS (Ser1177) in the peri-infarct region following PT stroke. In vitro study further indicated that OGD increased p21, endostatin, and DNA damage (γH2AX) levels in the brain endothelial cell line, but they were reversed by PBMT. Intriguingly, the beneficial effects of PBMT were attenuated by a NOS inhibitor. In summary, these findings provide novel insights into the role of eNOS in PBMT-mediated protection against cerebrovascular senescence and endothelial dysfunction following ischemia. The use of PBMT as a therapeutic is a promising strategy to improve endothelial function in cerebrovascular disease.

Differences in carotid to femoral pulse wave velocity and carotid intima media thickness between vegetarian and omnivorous diets in healthy subjects: a systematic review and meta-analysis

Background: Arterial stiffness and atherosclerosis are known risk factors for cardiovascular morbidity and mortality. Vegetarian diets have been associated with cardiovascular benefits, including improvements in metabolic parameters. However, the impact of a vegetarian diet on cardiovascular parameters, specifically arterial stiffness and atherosclerosis, in healthy individuals remains unclear. Thus, this study aims to analyze differences in arterial stiffness and atherosclerosis between vegetarian and omnivorous diets in healthy subjects. Methods: A systematic review and meta-analysis were conducted following established guidelines. PubMed, Scopus, Web of Science, and Cochrane Library databases were searched for studies examining the association between vegetarian and omnivorous diets with arterial stiffness and atherosclerosis. Cross-sectional studies reporting carotid to femoral pulse wave velocity (cf-PWv) as a measure of arterial stiffness and carotid intima media thickness (c-IMT) as a measure of atherosclerosis were included. Data were synthesized using random effects models, and sensitivity analyses, meta-regressions, and assessment of publication bias were performed. Results: Ten studies were included in the systematic review, and seven studies were included in the meta-analysis. The pooled analysis demonstrated that individuals following a vegetarian diet had differences in the levels of arterial stiffness (cf-PWv) compared to those following an omnivorous diet (MD: -0.43 m s-1; 95% CI: -0.63, -0.23). Similarly, atherosclerosis (c-IMT) was found to be different in individuals adhering to a vegetarian dietary pattern (MD = -29.86 mm; 95% CI: -58.41, -1.32). Conclusions: Our findings suggest that a vegetarian diet is associated with improved arterial stiffness and reduced atherosclerosis in healthy individuals. These results support the inclusion of a well-balanced vegetarian dietary pattern in the prevention and management of cardiovascular diseases. However, further research is needed to explore the effects of a vegetarian diet on arterial health in diverse populations and to assess long-term cardiovascular outcomes.

Regulated translocation of neutral sphingomyelinase-2 to the plasma membrane drives insulin resistance in steatotic hepatocytes

Obesity-associated diabetes is linked to the accumulation of ceramide in various organs, including the liver. The exact mechanisms by which ceramide contributes to diabetic pathology are unclear, but one proposed scenario is that ceramide accumulation may inhibit insulin signaling pathways. It is unknown however whether the excess ceramide is generated proximal to the insulin receptor, that is, at the plasma membrane (PM), where it could affect the insulin signaling pathway directly, or the onset of insulin resistance is due to ceramide-induced mitochondrial dysfunction and/or lipotoxicity. Using hepatic cell lines and primary cultures, gain- and loss- of function approach, and state-of-the art lipid imaging, this study shows that PM-associated neutral sphingomyelinase 2 (nSMase2) regulates ceramide homeostasis in fat-loaded hepatocytes and drives the onset of insulin resistance. Our results provide evidence of a regulated translocation of nSMase2 to the PM which leads to local generation of ceramide and insulin resistance in cells treated with palmitic acid (PAL), a type of fat commonly found in diabetogenic diets. Oleic acid, which also causes accumulation of lipid droplets, does not induce nSMase2 translocation and insulin resistance. Experiments using the acyl-biotin exchange method to quantify protein palmitoylation show that cellular PAL abundance regulates the rate of nSMase2 palmitoylation. Furthermore, while inhibition of nSMase2 with GW4869 prevents PAL-induced insulin resistance, the overexpression of wild type nSMase2 but not palmitoylation-defective mutant protein potentiates the suppressive effect of PAL on insulin signaling. Overall, this study identifies nSMase2 as a novel component of the mechanism of insulin resistance onset in fat-loaded hepatocytes, that is, cell-autonomous and driven by PAL.

Ceramide in cerebrovascular diseases

Ceramide, a bioactive sphingolipid, serves as an important second messenger in cell signal transduction. Under stressful conditions, it can be generated from de novo synthesis, sphingomyelin hydrolysis, and/or the salvage pathway. The brain is rich in lipids, and abnormal lipid levels are associated with a variety of brain disorders. Cerebrovascular diseases, which are mainly caused by abnormal cerebral blood flow and secondary neurological injury, are the leading causes of death and disability worldwide. There is a growing body of evidence for a close connection between elevated ceramide levels and cerebrovascular diseases, especially stroke and cerebral small vessel disease (CSVD). The increased ceramide has broad effects on different types of brain cells, including endothelial cells, microglia, and neurons. Therefore, strategies that reduce ceramide synthesis, such as modifying sphingomyelinase activity or the rate-limiting enzyme of the de novo synthesis pathway, serine palmitoyltransferase, may represent novel and promising therapeutic approaches to prevent or treat cerebrovascular injury-related diseases.

Emerging Roles of Endothelial Nitric Oxide in Preservation of Cognitive Health

eNOS (endothelial nitric oxide synthase) is critically important enzyme responsible for regulation of cardiovascular homeostasis. Under physiological conditions, constitutive eNOS activity and production of endothelial nitric oxide (NO) exert essential neurovascular protective functions. In this review, we first discuss the roles of endothelial NO in prevention of neuronal amyloid accumulation and formation of neurofibrillary tangles, hallmarks of Alzheimer disease pathology. Next, we review existing evidence suggesting that NO released from endothelium prevents activation of microglia, stimulates glycolysis in astrocytes, and increases biogenesis of mitochondria. We also address major risk factors for cognitive impairment including aging and ApoE4 (apolipoprotein 4) genotype with focus on their detrimental effects on eNOS/NO signaling. Relevant to this review, recent studies suggested that aged eNOS heterozygous mice are unique model of spontaneous cerebral small vessel disease. In this regard, we review contribution of dysfunctional eNOS to deposition of Aβ (amyloid-β) into blood vessel wall leading to development of cerebral amyloid angiopathy. We conclude that endothelial dysfunction manifested by the loss of neurovascular protective functions of NO may significantly contribute to development of cognitive impairment.

Sphingolipids and Atherosclerosis: The Dual Role of Ceramide and Sphingosine-1-Phosphate

Sphingolipids are bioactive molecules that play either pro- and anti-atherogenic roles in the formation and maturation of atherosclerotic plaques. Among SLs, ceramide and sphingosine-1-phosphate showed antithetic properties in regulating various molecular mechanisms and have emerged as novel potential targets for regulating the development of atherosclerosis. In particular, maintaining the balance of the so-called ceramide/S1P rheostat is important to prevent the occurrence of endothelial dysfunction, which is the trigger for the entire atherosclerotic process and is strongly associated with increased oxidative stress. In addition, these two sphingolipids, together with many other sphingolipid mediators, are directly involved in the progression of atherogenesis and the formation of atherosclerotic plaques by promoting the oxidation of low-density lipoproteins (LDL) and influencing the vascular smooth muscle cell phenotype. The modulation of ceramide and S1P levels may therefore allow the development of new antioxidant therapies that can prevent or at least impair the onset of atherogenesis, which would ultimately improve the quality of life of patients with coronary artery disease and significantly reduce their mortality.

The association of urinary prostaglandins with uric acid in hyperuricemia patients

Purpose

To explore the association between uric acid and urinary prostaglandins in male patients with hyperuricemia.

Methods

A total of 38 male patients with hyperuricemia in outpatients of Huadong Hospital from July 2018 to January 2020 were recruited. Serum uric acid (SUA), 24 h urinary uric acid excretion and other indicators were detected respectively. 10 ml urine was taken to determine prostaglandin prostaglandin D (PGD), prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), 6-keto-PGF1α, thromboxane A2 (TXA2) and thromboxane B2 (TXB2). Fraction of uric acid excretion (FEua) and uric acid clearance rate (Cua) were calculated. According to the mean value of FEua and Cua, patients were divided into two groups, respectively. The independent-samples t test and the Mann–Whitney U test were applied for normally and non-normally distributed data, respectively.

Results

After adjusting confounding factors (age, BMI, eGFR, TG, TC, HDL and LDL), SUA was negatively correlated with urinary PGE1(r = -0.615, P = 0.009) and PGE2(r = -0.824, P < 0.001). Compared with SUA1 group (SUA < 482.6 mg/dl), SUA2 (SUA \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 482.6 mg/dl) had lower urinary PGE1(P = 0.022) and PGE2(P = 0.019) levels. Cua was positively correlated with PGE2 (r = 0.436, P = 0.01). The correlation persisted after adjustment for age, BMI, eGFR, TG, TC, HDL and LDL by multiple linear regression analysis. In the Cua1 group (Cua < 4.869 mL /min/1.73 m²), PGE2 were lower than that in Cua2 (Cua \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 4.869 mL /min/1.73 m²) group (P = 0.011).

Conclusions

In male patients with hyperuricemia, SUA was negatively correlated with urinary PGE2, Cua was positively correlated with urinary PGE2. Urinary PGE2 were significantly different between different SUA and Cua groups.

Obesity as a premature aging phenotype - implications for sarcopenic obesity

Obesity and aging have both seen dramatic increases in prevalence throughout society. This review seeks to highlight common pathologies that present with obesity, along with the underlying risk factors, that have remarkable similarity to what is observed in the aged. These include skeletal muscle dysfunction (loss of quantity and quality), significant increases in adiposity, systemic alterations to autonomic dysfunction, reduction in nitric oxide bioavailability, increases in oxidant stress and inflammation, dysregulation of glucose homeostasis, and mitochondrial dysfunction. This review is organized by the aforementioned indices and succinctly highlights literature that demonstrates similarities between the aged and obese phenotypes in both human and animal models. As aging is an inevitability and obesity prevalence is unlikely to significantly decrease in the near future, these two phenotypes will ultimately combine as a multidimensional syndrome (a pathology termed sarcopenic obesity). Whether the pre-mature aging indices accompanying obesity are additive or synergistic upon entering aging is not yet well defined, but the goal of this review is to illustrate the potential consequences of a double aged phenotype in sarcopenic obesity. Clinically, the modifiable risk factors could be targeted specifically in obesity to allow for increased health span in the aged and sarcopenic obese populations.

Chicken muscle hydrolysate reduces blood pressure in spontaneously hypertensive rats, upregulates ACE2, and ameliorates vascular inflammation, fibrosis, and oxidative stress

Spent hens are egg-laying chicken reaching the end of their egg-laying cycle and are seen as a by-product to the egg industry. A spent hen muscle protein hydrolysate prepared by food-grade thermoase PC10F (SPH-T) has previously shown antihypertensive potential. In the present work, we further investigated its antihypertensive effect and underlying mechanisms in spontaneously hypertensive rats. There are three groups: untreated, low dose (250 mg SPH-T/kg/day body weight), and high dose (1,000 mg SPH-T/kg/day body weight). Oral administration of SPH-T over a period of 20 days reduced systolic blood pressure by 25.7 mm Hg (p < 0.001) and 11.9 mm Hg (p < 0.05), respectively, for the high- and low-dose groups. The high-dose treatment decreased the circulating level of angiotensin II (from 25.0 to 5.7 pg/ml) while increased angiotensin-converting enzyme 2 (ACE2) (from 1.3 to 3.3 IU/ml) and angiotensin (1-7) (from 37.0 to 70.1 pg/ml) significantly (p < 0.05). Furthermore, the high-dose group doubled the aortic expression of ACE2 while reduced the expression of angiotensin (Ang) II type 1 receptor (by 35%). Circulating inflammatory cytokines including tumor necrosis factor alpha and monocyte chemoattractant protein-1 as well as vascular inflammatory proteins including inducible nitric oxide synthase and vascular cell adhesion molecule-1 were attenuated by ∼15%-50% by the treatment; nitrosative stress (35%) and type I collagen synthesis (50%) in the aorta were also attenuated significantly (p < 0.05). Moreover, SPH-T possessed an umami taste (no obvious bitter taste) as analyzed by electronic tongue. PRACTICAL APPLICATION: Hypertension is a global health concern, afflicting more than 20% of adults worldwide. Uncovering the antihypertensive effect of spent hen protein hydrolysate underpinned its functional food nutraceutical applications for the prevention and treatment of hypertension.

Nitric Oxide: The Missing Factor in COVID-19 Severity?

Coronavirus disease 2019 (COVID-19) is a contagious respiratory and vascular disease that continues to spread among people around the world, mutating into new strains with increased transmission rates, such as the delta variant. The scientific community is struggling to discover the link between negative COVID-19 outcomes in patients with preexisting conditions, as well as identify the cause of the negative clinical patient outcomes (patients who need medical attention, including hospitalization) in what seems like a widespread range of COVID-19 symptoms that manifest atypically to any preexisting respiratory tract infectious diseases known so far. Having successfully developed a nutritional formulation intervention based on nitrate, a nitric oxide precursor, the authors hypothesis is that both the comorbidities associated with negative clinical patient outcomes and symptoms associated with COVID-19 sickness are linked to the depletion of a simple molecule: nitric oxide.

Ceramides and other sphingolipids as drivers of cardiovascular disease

Increases in calorie consumption and sedentary lifestyles are fuelling a global pandemic of cardiometabolic diseases, including coronary artery disease, diabetes mellitus, cardiomyopathy and heart failure. These lifestyle factors, when combined with genetic predispositions, increase the levels of circulating lipids, which can accumulate in non-adipose tissues, including blood vessel walls and the heart. The metabolism of these lipids produces bioactive intermediates that disrupt cellular function and survival. A compelling body of evidence suggests that sphingolipids, such as ceramides, account for much of the tissue damage in these cardiometabolic diseases. In humans, serum ceramide levels are proving to be accurate biomarkers of adverse cardiovascular disease outcomes. In mice and rats, pharmacological inhibition or depletion of enzymes driving de novo ceramide synthesis prevents the development of diabetes, atherosclerosis, hypertension and heart failure. In cultured cells and isolated tissues, ceramides perturb mitochondrial function, block fuel usage, disrupt vasodilatation and promote apoptosis. In this Review, we discuss the body of literature suggesting that ceramides are drivers - and not merely passengers - on the road to cardiovascular disease. Moreover, we explore the feasibility of therapeutic strategies to lower ceramide levels to improve cardiovascular health.

Neutral sphingomyelinase-2 and cardiometabolic diseases

Sphingolipids, in particular ceramides, play vital role in pathophysiological processes linked to metabolic syndrome, with implications in the development of insulin resistance, pancreatic ß-cell dysfunction, type 2 diabetes, atherosclerosis, inflammation, nonalcoholic steatohepatitis, and cancer. Ceramides are produced by the hydrolysis of sphingomyelin, catalyzed by different sphingomyelinases, including neutral sphingomyelinase 2 (nSMase2), whose dysregulation appears to underlie many of the inflammation-related pathologies. In this review, we discuss the current knowledge on the biochemistry of nSMase2 and ceramide production and its regulation by inflammatory cytokines, with particular reference to cardiometabolic diseases. nSMase2 contribution to pathogenic processes appears to involve cyclical feed-forward interaction with proinflammatory cytokines, such as TNF-α and IL-1ß, which activate nSMase2 and the production of ceramides, that in turn triggers the synthesis and release of inflammatory cytokines. We elaborate these pathogenic interactions at the molecular level and discuss the potential therapeutic benefits of inhibiting nSMase2 against inflammation-driven cardiometabolic diseases.

Mechanical Fingerprint of Senescence in Endothelial Cells

Endothelial senescence entails alterations of the healthy cell phenotype, which accumulate over time and contribute to cardiovascular disease. Mechanical aspects regulating cell adhesion, force generation, and the response to flow contribute to the senescence-associated drift; however, they remain largely unexplored. Here, we exploit force microscopy to resolve variations of the cell anchoring to the substrate and the tractions generated upon aging in the nanonewton (nN) range. Senescent endothelial cells display a multifold increase in the levels of basal adhesion and force generation supported by mature and strong focal adhesions. The enhanced mechanical interaction with the substrate yields static endothelial monolayers that polarize in response to flow but fail the process of coordinated cell shape remodeling and reorientation. The emerging picture indicates that senescence reinforces the local cell interaction with the substrate and may therefore prevent endothelial denudation; however, it compromises the ability to functionally adapt to the local hemodynamic conditions.

The Risk Factors of Coronary Heart Disease and its Relationship with Endothelial Nitric Oxide Synthase

BACKGROUND: Coronary heart disease (CHD) is the leading cause of death and start with injury to the endothelium of a coronary artery. The common feature of endothelial dysfunction is a decrease of nitric oxide (NO) bioavailability that regulated by endothelial NO synthase (eNOS) activity. AIM: The aim of our study was to study the relationship between risk factors of CHD patients with the level of eNOS. METHODS: Thirty-seven outpatients in cardiology department of the regional public hospital diagnosed as CHD were included in our study. Thirty healthy individuals were included as the control group. Risk factors of CHD were identified according to anamnesis and laboratory finding. eNOS was measured by ELISA methods. RESULTS: Endothelial NOS levels were significantly higher in the CHD when compared to the controls (p < 0.05). The most dominant risk factor for CHD is overweight, and followed by dyslipidemia, smoking, hypertension, history of CHD, and diabetes mellitus. eNOS in CHD patients who had one risk factor was 37.598 ± 0.1541 ng/ml, two risk factors 42.154 ± 22.329 ng/ml, three risk factors 25.329 ± 6.083 ng/ml, four risk factors 22.483 ± 4.022 ng/ml, and five risk factors 15.994 ± 4.774 ng/ml. There were significant differences in the average eNOS levels based on the number of risk factors (p < 0.05), and a tendency that more risk factors in CHD patients, the lower the average level of eNOS. CONCLUSION: In our study, eNOS levels showed highly significant relation with CHD and related to the number of risk factors those the CHD patients had.

Circulating ceramides as biomarkers of cardiovascular disease: Evidence from phenotypic and genomic studies

There is a need for new biomarkers of atherosclerotic cardiovascular disease (ACVD), the main cause of death globally. Ceramides, a class of potent bioactive lipid mediators, have signalling roles in apoptosis, cellular stress and inflammation. Recent studies have highlighted circulating ceramides as novel biomarkers of coronary artery disease, type-2 diabetes and insulin resistance. Ceramides are highly regulated by enzymatic reactions throughout the body in terms of their activity and metabolism, including production, degradation and transport. The genetic studies that have been completed to date on the main ceramide species found in circulation are described, highlighting the importance of DNA variants in genes involved in ceramide biosynthesis as key influencers of heritable, circulating ceramide levels. We also review studies of disease associations with ceramides and discuss mechanistic insights deriving from recent genomic studies. The signalling activities of ceramides in vascular inflammation and apoptosis, associations between circulating ceramides and coronary artery disease risk, type-2 diabetes and insulin resistance, and the potential importance of ceramides with regard to ACVD risk factors, such as blood pressure, lipoproteins and lifestyle factors, are also discussed.

Lipids: biomarkers of healthy aging

Life expectancy, and longevity have been increasing in recent years. However, this is, in most cases, accompanied by age-related diseases. Thus, it became essential to better understand the mechanisms inherent to aging, and to establish biomarkers that characterize this physiological process. Among all biomolecules, lipids appear to be a good target for the study of these biomarkers. In fact, some lipids have already been associated with age-related diseases. With the development of analytical techniques such as Mass Spectrometry, and Nuclear Magnetic Resonance, Lipidomics has been increasingly used to study pathological, and physiological states of an organism. Thus, the study of serum, and plasma lipidome in centenarians, and elderly individuals without age-related diseases can be a useful tool for the identification of aging biomarkers, and to understand physiological aging, and longevity. This review focus on the importance of lipids as biomarkers of aging, and summarize the changes in the lipidome that have been associated with aging, and longevity.

Spent Hen Muscle Protein-Derived RAS Regulating Peptides Show Antioxidant Activity in Vascular Cells

Spent hens are egg-laying hens reaching the end of their egg-laying cycles, being a major byproduct of the egg industry. Recent studies have been focusing on finding new value-added uses for spent hens. We have previously identified four bioactive peptides from spent hen muscle proteins, including three angiotensin-converting enzyme (ACE) inhibitory (ACEi) peptides (VRP, LKY, and VRY), and one ACE2 upregulating (ACE2u) peptide (VVHPKESF (V-F)). In the current study, we further assessed their antioxidant and cytoprotective activities in two vascular cell lines-vascular smooth muscle A7r5 cells (VSMCs) and endothelial EA.hy926 cells (ECs)-upon stimulation by tumor necrosis factor alpha (TNFα) and angiotensin (Ang) II, respectively. The results from our study revealed that all four peptides attenuated oxidative stress in both cells. None of the investigated peptides altered the expression of TNFα receptors in ECs; however, VRY and V-F downregulated Ang II type 1 receptor (AT₁R), while V-F upregulated the Mas receptor (MasR) in VSMCs. Further, we found that the antioxidant effects of VRP, LKY, and VRY were likely through acting as direct radical scavengers, while that of V-F was at least partially ascribed to increased endogenous antioxidant enzymes (GPx4 and SOD2) in both cells. Besides, as an ACE2u peptide, V-F exerted antioxidant effect in a MasR-dependent manner, indicating a possible involvement of the upregulated ACE2-MasR axis underlying its antioxidant action. The antioxidant activities of VRP, LKY, VRY, and V-F in vascular cells indicated their multifunctional properties, in addition to their ACEi or ACE2u activity, which supports their potential use as functional food ingredients against hypertension.

Does eNOS derived nitric oxide protect the young from severe COVID-19 complications?

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Aging is the largest risk factors for severity and mortality in adult COVID-19.

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Severe cases of COVID-19 are related to vascular damage with evidence of direct viral infection in the endothelial cells.

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Increase risk of COVID-19 death are also highly related to disease with lower vascular Nitric Oxide (NO) level.

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Vascular viral defence by endothelial nitric oxide synthase (eNOS) derive NO may be the protecting factor for the young.

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eNOS polymorphism could potentially explain the disparity of COVID-19 mortality between Asian and non-Asian countries.

The COVID-19 pandemic poses an imminent threat to humanity, especially to the elderly. The molecular mechanisms underpinning the age-dependent disparity for disease progression is not clear. COVID-19 is both a respiratory and a vascular disease in severe patients. The damage endothelial system provides a good explanation for the various complications seen in COVID-19 patients. These observations lead us to suspect that endothelial cells are a barrier that must be breached before progression to severe disease. Endothelial intracellular defences are largely dependent of the activation of the interferon (IFN) system. Nevertheless, low type I and III IFNs are generally observed in COVID-19 patients suggesting that other intracellular viral defence systems are also activated to protect the young. Intriguingly, Nitric oxide (NO), which is the main intracellular antiviral defence, has been shown to inhibit a wide array of viruses, including SARS-CoV-1. Additionally, the increased risk of death with diseases that have underlying endothelial dysfunction suggest that endothelial NOS-derived nitric oxide could be the main defence mechanism. NO decreases dramatically in the elderly, the hyperglycaemic and the patients with low levels of vitamin D. However, eNOS derived NO occurs at low levels, unless it is during inflammation and co-stimulated by bradykinin. Regrettably, the bradykinin-induced vasodilation also progressively declines with age, thereby decreasing anti-viral NO production as well. Intriguingly, the inverse correlation between the percentage of WT eNOS haplotype and death per 100K population could potentially explain the disparity of COVID-19 mortality between Asian and non-Asian countries. These changes with age, low bradykinin and NO, may be the fundamental reasons that intracellular innate immunity declines with age leading to more severe COVID-19 complications.

P2Y Purinergic Receptors, Endothelial Dysfunction, and Cardiovascular Diseases

Purinergic G-protein-coupled receptors are ancient and the most abundant group of G-protein-coupled receptors (GPCRs). The wide distribution of purinergic receptors in the cardiovascular system, together with the expression of multiple receptor subtypes in endothelial cells (ECs) and other vascular cells demonstrates the physiological importance of the purinergic signaling system in the regulation of the cardiovascular system. This review discusses the contribution of purinergic P2Y receptors to endothelial dysfunction (ED) in numerous cardiovascular diseases (CVDs). Endothelial dysfunction can be defined as a shift from a “calm” or non-activated state, characterized by low permeability, anti-thrombotic, and anti-inflammatory properties, to a “activated” state, characterized by vasoconstriction and increased permeability, pro-thrombotic, and pro-inflammatory properties. This state of ED is observed in many diseases, including atherosclerosis, diabetes, hypertension, metabolic syndrome, sepsis, and pulmonary hypertension. Herein, we review the recent advances in P2Y receptor physiology and emphasize some of their unique signaling features in pulmonary endothelial cells.

The Role of Vascular Aging in Atherosclerotic Plaque Development and Vulnerability

BACKGROUND

The ongoing demographical shift is leading to an unprecedented aging of the population. As a consequence, the prevalence of age-related diseases, such as atherosclerosis and its thrombotic complications is set to increase in the near future. Endothelial dysfunction and vascular stiffening characterize arterial aging and set the stage for the development of cardiovascular diseases. Atherosclerotic plaques evolve over time, the extent to which these changes might affect their stability and predispose to sudden complications remains to be determined. Recent advances in imaging technology will allow for longitudinal prospective studies following the progression of plaque burden aimed at better characterizing changes over time associated with plaque stability or rupture. Oxidative stress and inflammation, firmly established driving forces of age-related CV dysfunction, also play an important role in atherosclerotic plaque destabilization and rupture. Several genes involved in lifespan determination are known regulator of redox cellular balance and pre-clinical evidence underlines their pathophysiological roles in age-related cardiovascular dysfunction and atherosclerosis.

OBJECTIVE

The aim of this narrative review is to examine the impact of aging on arterial function and atherosclerotic plaque development. Furthermore, we report how molecular mechanisms of vascular aging might regulate age-related plaque modifications and how this may help to identify novel therapeutic targets to attenuate the increased risk of CV disease in elderly people.

Ser-Tyr and Asn-Ala, vasorelaxing dipeptides found by comprehensive screening, reduce blood pressure via different age-dependent mechanisms

To understand the changes in physiological responses due to aging, a number of bioactive probes based on different signal transduction pathways are necessary. In this study, we comprehensively and systematically investigated changes in blood vessel function with age using a 336-dipeptide library.

In the early stage of hypertension, the most potent vasorelaxant dipeptide was Ser-Tyr (SY) in the mesenteric artery isolated from spontaneously hypertensive rats (SHR). SY-induced vasorelaxation and anti-hypertensive effects were blocked by L-NAME, an inhibitor of nitric oxide synthase (NOS), suggesting that SY activates the NO system. On the other hand, the patterns of dipeptides with vasorelaxation activity in early and advanced stages of hypertension were different. In the advanced stage, the most potent vasorelaxing dipeptide was Asn-Ala (NA). Orally administered NA (1.5 mg/kg) reduced the blood pressure in the advanced stage, at which drugs were sometimes less effective, and the anti-hypertensive effects lasted for 6 hr. The NA-induced vasorelaxation and anti-hypertensive activity was blocked by lorglumide, an antagonist of the cholecystokinin CCK₁ receptor, suggesting that NA activated the CCK system.

Taken together, in the early and advanced stages of hypertension, SY and NA exhibited vasorelaxing and anti-hypertensive effects via the NO and CCK systems, respectively.

Smooth muscle cell and arterial aging: basic and clinical aspects

Arterial aging engages a plethora of key signalling pathways that act in concert to induce vascular smooth muscle cell (VSMC) phenotypic changes leading to vascular degeneration and extracellular matrix degradation responsible for alterations of the mechanical properties of the vascular wall. This review highlights proof-of-concept examples of components of the extracellular matrix, VSMC receptors which connect extracellular and intracellular structures, and signalling pathways regulating changes in mechanotransduction and vascular homeostasis in aging. Furthermore, it provides a new framework for understanding how VSMC stiffness and adhesion to extracellular matrix contribute to arterial stiffness and how interactions with endothelial cells, platelets, and immune cells can regulate vascular aging. The identification of the key players of VSMC changes operating in large and small-sized arteries in response to increased mechanical load may be useful to better elucidate the causes and consequences of vascular aging and associated progression of hypertension, arteriosclerosis, and atherosclerosis.

The Effects of Age and Reproduction on the Lipidome of Caenorhabditis elegans

Aging is a complex life process, and a unified view is that metabolism plays key roles in all biological processes. Here, we determined the lipidomic profile of Caenorhabditis elegans (C. elegans) using ultraperformance liquid chromatography high-resolution mass spectrometry (UPLC-HRMS). Using a nontargeted approach, we detected approximately 3000 species. Analysis of the lipid metabolic profiles at young adult and ten-day-old ages among wild-type N2, glp-1 defective mutant, and double mutant daf-16;glp-1 uncovered significant age-related differences in the total amount of phosphatidylcholines (PC), sphingomyelins (SM), ceramides (Cer), diglycerides (DG), and triglycerides (TG). In addition, the age-associated lipid profiles were characterized by ratio of polyunsaturated (PUFA) over monounsaturated (MUFA) lipid species. Lipid metabolism modulation plays an important role in reproduction-regulated aging; to identify the variations of lipid metabolites during germ line loss-induced longevity, we investigated the lipidomic profiles of long-lived glp-1/notch receptor mutants, which have reproductive deficiency when grown at nonpermissive temperature. The results showed that there was some age-related lipid variation, including TG 40:2, TG 40:1, and TG 41:1, which contributed to the long-life phenotype. The longevity of glp-1 mutant was daf-16-dependent; the lipidome analysis of daf-16;glp-1 double mutant revealed that the changes of some metabolites in the glp-1 mutant were daf-16-dependent, while other metabolites displayed more complex epistatic patterns. We first conducted a comprehensive lipidome analysis to provide novel insights into the relationships between longevity and lipid metabolism regulated by germ line signals in C. elegans.

Ceramide and Regulation of Vascular Tone

In addition to playing a role as a structural component of cellular membranes, ceramide is now clearly recognized as a bioactive lipid implicated in a variety of physiological functions. This review aims to provide updated information on the role of ceramide in the regulation of vascular tone. Ceramide may induce vasodilator or vasoconstrictor effects by interacting with several signaling pathways in endothelial and smooth muscle cells. There is a clear, albeit complex, interaction between ceramide and redox signaling. In fact, reactive oxygen species (ROS) activate different ceramide generating pathways and, conversely, ceramide is known to increase ROS production. In recent years, ceramide has emerged as a novel key player in oxygen sensing in vascular cells and mediating vascular responses of crucial physiological relevance such as hypoxic pulmonary vasoconstriction (HPV) or normoxic ductus arteriosus constriction. Likewise, a growing body of evidence over the last years suggests that exaggerated production of vascular ceramide may have detrimental effects in a number of pathological processes including cardiovascular and lung diseases.

Role of sphingolipids in senescence: implication in aging and age-related diseases

Aging is defined as the progressive deterioration of physiological function with age. Incidence of many pathologies increases with age, including neurological and cardiovascular diseases and cancer. Aging tissues become less adaptable and renewable, and cells undergo senescence, a process by which they "irreversibly" stop dividing. Senescence has been shown to serve as a tumor suppression mechanism with clear desirable effects. However, senescence also has deleterious consequences, especially for cardiovascular, metabolic, and immune systems. Sphingolipids are a major class of lipids that regulate cell biology, owing to their structural and bioactive properties and diversity. Their involvement in the regulation of aging and senescence has been demonstrated and studied in multiple organisms and cell types, especially that of ceramide and sphingosine-1-phosphate; ceramide induces cellular senescence and sphingosine-1-phosphate delays it. These discoveries could be very useful in the future to understand aging mechanisms and improve therapeutic interventions.

Enriched Expression of Neutral Sphingomyelinase 2 in the Striatum is Essential for Regulation of Lipid Raft Content and Motor Coordination

Sphingomyelinases are a family of enzymes that hydrolyze sphingomyelin to generate phosphocholine and ceramide. The brain distribution and function of neutral sphingomyelinase 2 (nSMase2) were elucidated in this study. nSMase2 mRNA expression was greatest in the striatum, followed by the prefrontal cortex, hippocampus, cerebellum, thalamus, brainstem, and olfactory bulb. The striatum had the highest level of nSMase2 protein expression, followed by the prefrontal cortex, thalamus, hippocampus, brainstem, and cerebellum. Dense immunolabeling was observed in the striatum, including the caudate-putamen, while moderately dense staining was found in the olfactory bulb and cerebral neocortex. Electron microscopy of the caudate-putamen showed nSMase2 immunoreaction product was present in small diameter dendrites or dendritic spines, that formed asymmetrical synapses with unlabeled axon terminals containing small round vesicles; and characteristics of glutamatergic axons. Lipidomic analysis of the striatum showed increase in long chain sphingomyelins, SM36:1 and SM38:1 after inhibition of nSMase activity. Quantitative proteomic analysis of striatal lipid raft fraction showed many proteins were downregulated by more than 2-fold after inhibition or antisense knockdown of nSMase; consistent with the notion that nSMase2 activity is important for aggregation or clustering of proteins in lipid rafts. Inhibition or antisense knockdown of nSMase2 in the caudate-putamen resulted in motor deficits in the rotarod and narrow beam tests; as well as decreased acoustic startle and improved prepulse inhibition of the startle reflex. Together, results indicate an important function of nSMase2 in the striatum.

Prostaglandins in the pathogenesis of kidney diseases

Prostaglandins (PGs) are important lipid mediators produced from arachidonic acid via the sequential catalyzation of cyclooxygenases (COXs) and specific prostaglandin synthases. There are five subtypes of PGs, namely PGE2, PGI2, PGD2, PGF2α, and thromboxane A2 (TXA2). PGs exert distinct roles by combining to a diverse family of membrane-spanning G protein-coupled prostanoid receptors. The distribution of these PGs, their specific synthases and receptors vary a lot in the kidney. This review summarized the recent findings of PGs together with the COXs and their specific synthases and receptors in regulating renal function and highlighted the insights into their roles in the pathogenesis of various kidney diseases.

Photobiomodulation (PBM) therapy at 904 nm mitigates effects of exercise-induced skeletal muscle fatigue in young women

Muscle fatigue is a process influenced by several mechanisms such as concentration of metabolic substrates, changes in blood flow, and increases in reactive oxygen species that impair contractile muscle function. In this context, photobiomodulation has been investigated for preventing muscle fatigue, with reports of positive effects on muscle performance. This study aimed to investigate the effects of 904-nm LASER photobiomodulation on rectus femoris muscle performance in young women. Eighteen young women participated in a randomized, participant and assessor-blinded crossover trial with placebo control. Active LASER (904 nm, 60 mW, 250 Hz, 3.6 J per diode, total dose of 129.6 J) intervention was applied prior to an isokinetic fatigue protocol consisting of a set of 60 concentric quadricep contractions at a constant dynamometer angular velocity of 180°/s. Compared to placebo, LASER photobiomodulation significantly reduced muscle fatigue across a range of indicators including reduced ratings of perceived exertion (P = 0.0139), and increased electromyographic fatigue index (EFI) (P = 0.005). The isokinetic dynamometer performance analysis demonstrated that LASER photobiomodulation increased peak torque (P = 0.04), time to peak torque (P = 0.042), total work (P = 0.032), average power (P = 0.0007), and average peak torque (P = 0.019) between both experimental conditions. No significant difference was observed for work fatigue index (P = 0.29) or for lactate concentration (P > 0.05). Photobiomodulation at 904 nm was effective in reducing fatigue levels and increasing muscle performance in young active women but had no effect on lactate levels.

Sphingosine 1-phosphate activation of ERM contributes to vascular calcification

Vascular calcification is the deposition of mineral in the artery wall by vascular smooth muscle cells (VSMCs) in response to pathological stimuli. The process is similar to bone formation and is an independent risk factor for cardiovascular disease. Given that ceramide and sphingosine 1-phosphate (S1P) are involved in cardiovascular pathophysiology and biomineralization, their role in VSMC matrix mineralization was investigated. During phosphate-induced VSMC mineralization, endogenous S1P levels increased accompanied by increased sphingosine kinase (SK) activity and increased mRNA expression of SK1 and SK2. Consistent with this, mineralization was increased by exogenous S1P, but decreased by C2-ceramide. Mechanistically, exogenous S1P stimulated ezrin-radixin-moesin (ERM) phosphorylation in VSMCs and ERM phosphorylation was increased concomitantly with endogenous S1P during mineralization. Moreover, inhibition of acid sphingomyelinase and ceramidase with desipramine prevented increased S1P levels, ERM activation, and mineralization. Finally, pharmacological inhibition of ERM phosphorylation with NSC663894 decreased mineralization induced by phosphate and exogenous S1P. Although further studies will be needed to verify these findings in vivo, this study defines a novel role for the SK-S1P-ERM pathways in phosphate-induced VSMC matrix mineralization and shows that blocking these pathways with pharmacological inhibitors reduces mineralization. These results may inform new therapeutic approaches to inhibit or delay vascular calcification.

Endothelial Cell Autophagy Maintains Shear Stress-Induced Nitric Oxide Generation via Glycolysis-Dependent Purinergic Signaling to Endothelial Nitric Oxide Synthase

OBJECTIVE

Impaired endothelial cell (EC) autophagy compromises shear stress-induced nitric oxide (NO) generation. We determined the responsible mechanism.

APPROACH AND RESULTS

On autophagy compromise in bovine aortic ECs exposed to shear stress, a decrease in glucose uptake and EC glycolysis attenuated ATP production. We hypothesized that decreased glycolysis-dependent purinergic signaling via P2Y1 (P2Y purinoceptor 1) receptors, secondary to impaired autophagy in ECs, prevents shear-induced phosphorylation of eNOS (endothelial nitric oxide synthase) at its positive regulatory site S1117 (p-eNOS^S1177) and NO generation. Maneuvers that restore glucose transport and glycolysis (eg, overexpression of GLUT1 [glucose transporter 1]) or purinergic signaling (eg, addition of exogenous ADP) rescue shear-induced p-eNOS^S1177 and NO production in ECs with impaired autophagy. Conversely, inhibiting glucose transport via GLUT1 small interfering RNA, blocking purinergic signaling via ectonucleotidase-mediated ATP/ADP degradation (eg, apyrase), or inhibiting P2Y1 receptors using pharmacological (eg, MRS2179 [2'-deoxy-N⁶-methyladenosine 3',5'-bisphosphate tetrasodium salt]) or genetic (eg, P2Y1-receptor small interfering RNA) procedures inhibit shear-induced p-eNOS^S1177 and NO generation in ECs with intact autophagy. Supporting a central role for PKCδ^T505 (protein kinase C delta T505) in relaying the autophagy-dependent purinergic-mediated signal to eNOS, we find that (1) shear stress-induced activating phosphorylation of PKCδ^T505 is negated by inhibiting autophagy, (2) shear-induced p-eNOS^S1177 and NO generation are restored in autophagy-impaired ECs via pharmacological (eg, bryostatin) or genetic (eg, constitutively active PKCδ) activation of PKCδ^T505, and (3) pharmacological (eg, rottlerin) and genetic (eg, PKCδ small interfering RNA) PKCδ inhibition prevents shear-induced p-eNOS^S1177 and NO generation in ECs with intact autophagy. Key nodes of dysregulation in this pathway on autophagy compromise were revealed in human arterial ECs.

CONCLUSIONS

Targeted reactivation of purinergic signaling and PKCδ has strategic potential to restore compromised NO generation in pathologies associated with suppressed EC autophagy.

The human plasma-metabolome: Reference values in 800 French healthy volunteers; impact of cholesterol, gender and age

Metabolomic approaches are increasingly used to identify new disease biomarkers, yet normal values of many plasma metabolites remain poorly defined. The aim of this study was to define the "normal" metabolome in healthy volunteers. We included 800 French volunteers aged between 18 and 86, equally distributed according to sex, free of any medication and considered healthy on the basis of their medical history, clinical examination and standard laboratory tests. We quantified 185 plasma metabolites, including amino acids, biogenic amines, acylcarnitines, phosphatidylcholines, sphingomyelins and hexose, using tandem mass spectrometry with the Biocrates AbsoluteIDQ p180 kit. Principal components analysis was applied to identify the main factors responsible for metabolome variability and orthogonal projection to latent structures analysis was employed to confirm the observed patterns and identify pattern-related metabolites. We established a plasma metabolite reference dataset for 144/185 metabolites. Total blood cholesterol, gender and age were identified as the principal factors explaining metabolome variability. High total blood cholesterol levels were associated with higher plasma sphingomyelins and phosphatidylcholines concentrations. Compared to women, men had higher concentrations of creatinine, branched-chain amino acids and lysophosphatidylcholines, and lower concentrations of sphingomyelins and phosphatidylcholines. Elderly healthy subjects had higher sphingomyelins and phosphatidylcholines plasma levels than young subjects. We established reference human metabolome values in a large and well-defined population of French healthy volunteers. This study provides an essential baseline for defining the "normal" metabolome and its main sources of variation.

The Nutraceutical Dehydrozingerone and Its Dimer Counteract Inflammation- and Oxidative Stress-Induced Dysfunction of In Vitro Cultured Human Endothelial Cells: A Novel Perspective for the Prevention and Therapy of Atherosclerosis

Atherosclerosis is characterized by endothelial dysfunction, mainly induced by inflammation and oxidative stress. Increased reactive oxygen species (ROS) production together with increased adhesion molecules and thrombogenic tissue factor (TF) expression on endothelial cells has a key role in proatherogenic mechanisms. Therefore downmodulation of these molecules could be useful for reducing the severity of inflammation and atherosclerosis progression. Dehydrozingerone (DHZ) is a nutraceutical compound with anti-inflammatory and antioxidant activities. In this study we evaluated the ability of DHZ and its symmetric dimer to modulate hydrogen peroxide- (H₂O₂-) induced ROS production in human umbilical vein endothelial cells (HUVEC). We also evaluated intercellular adhesion molecule- (ICAM-) 1, vascular cell adhesion molecule- (VCAM-) 1, and TF expression in HUVEC activated by tumor necrosis factor- (TNF-) α. HUVEC pretreatment with DHZ and DHZ dimer reduced H₂O₂-induced ROS production and inhibited adhesion molecule expression and secretion. Of note, only DHZ dimer was able to reduce TF expression. DHZ effects were in part mediated by the inhibition of the nuclear factor- (NF-) κB activation. Overall, our findings demonstrate that the DHZ dimer exerts a potent anti-inflammatory, antioxidant, and antithrombotic activity on endothelial cells and suggest potential usefulness of this compound to contrast the pathogenic mechanisms involved in atherosclerosis progression.

Sphingolipid De Novo Biosynthesis: A Rheostat of Cardiovascular Homeostasis

Sphingolipids (SL) are both fundamental structural components of the eukaryotic membranes and signaling molecules that regulate a variety of biological functions. The highly-bioactive lipids, ceramide and sphingosine-1-phosphate, have emerged as important regulators of cardiovascular function in health and disease. In this review we discuss recent insights into the role of SLs, particularly ceramide and sphingosine-1-phosphate, in the pathophysiology of the cardiovascular system. We also highlight advances into the molecular mechanisms regulating serine palmitoyltransferase, the first and rate-limiting enzyme of de novo SL biosynthesis, with an emphasis on the recently discovered inhibitors of serine palmitoyltransferase, ORMDL and NOGO-B proteins. Understanding the molecular mechanisms regulating this biosynthetic pathway may lead to the development of novel therapeutic approaches for the treatment of cardiovascular diseases.

Polyphenol-based nutraceuticals for the prevention and treatment of cardiovascular disease: Review of human evidence

BACKGROUND

In addition to prescription drugs, nutraceuticals/functional foods/medical foods are being increasingly added as adjunct treatment of cardiovascular disease (CVD), even though most of them have been exclusively studied in vitro.

HYPOTHESIS/PURPOSE

We review the available evidence (focusing on when the amount of polyphenols' intake was measured) coming from randomized controlled trials (RCTs) of (poly)phenol-based supplements.

CONCLUSION

We conclude that (poly)phenol-based nutraceuticals and functional foods might be indeed used as adjunct therapy of CVD, but additional long-term RCTs with adequate numerosity and with clinically relevant end points are needed to provide unequivocal evidence of their clinical usefulness.

Ceramide-Initiated Protein Phosphatase 2A Activation Contributes to Arterial Dysfunction In Vivo

Prior studies have implicated accumulation of ceramide in blood vessels as a basis for vascular dysfunction in diet-induced obesity via a mechanism involving type 2 protein phosphatase (PP2A) dephosphorylation of endothelial nitric oxide synthase (eNOS). The current study sought to elucidate the mechanisms linking ceramide accumulation with PP2A activation and determine whether pharmacological inhibition of PP2A in vivo normalizes obesity-associated vascular dysfunction and limits the severity of hypertension. We show in endothelial cells that ceramide associates with the inhibitor 2 of PP2A (I2PP2A) in the cytosol, which disrupts the association of I2PP2A with PP2A leading to its translocation to the plasma membrane. The increased association between PP2A and eNOS at the plasma membrane promotes dissociation of an Akt-Hsp90-eNOS complex that is required for eNOS phosphorylation and activation. A novel small-molecule inhibitor of PP2A attenuated PP2A activation, prevented disruption of the Akt-Hsp90-eNOS complex in the vasculature, preserved arterial function, and maintained normal blood pressure in obese mice. These findings reveal a novel mechanism whereby ceramide initiates PP2A colocalization with eNOS and demonstrate that PP2A activation precipitates vascular dysfunction in diet-induced obesity. Therapeutic strategies targeted to reducing PP2A activation might be beneficial in attenuating vascular complications that exist in the context of type 2 diabetes, obesity, and conditions associated with insulin resistance.

Superoxide dismutase 1 and glutathione peroxidase 1 are involved in the protective effect of sulodexide on vascular endothelial cells exposed to oxygen-glucose deprivation

Sulodexide (SDX) is widely used in the treatment of both arterial and venous thrombotic disorders. In addition to its recognized antithrombotic action, SDX has endothelial protective potential, which is independent of the coagulation/fibrinolysis system. However, the detailed molecular mechanisms of the endothelioprotective action of the drug are still unresolved. The aim of the present study was to determine whether treatment with SDX at concentrations of 0.125-0.5 lipase releasing unit (LRU)/ml have on the expression and activity of antioxidant enzymes in ischemic endothelial cells and how these effects might be related to the antiapoptotic properties of SDX. In the present study, human umbilical vein endothelial cells (HUVECs) were subjected to ischemia-simulating conditions (combined oxygen and glucose deprivation, OGD) for 6h to determine the protective effects of SDX. SDX (0.25 and 0.5LRU/ml) in OGD significantly increased the cell viability and prevented mitochondrial depolarization in the HUVECs. Moreover, SDX protected the HUVECs against OGD-induced apoptosis. At concentrations of 0.25 and 0.5LRU/ml, the drug increased both superoxide dismutase 1 (SOD1) and glutathione peroxidase 1 (GPx1) mRNA/protein expression together with a significant attenuation of oxidative stress in ischemic HUVECs. Our findings also demonstrate that an increase in both SOD and GPx activity is involved in the protective effect of SDX on ischemic endothelial cells. Altogether, these results suggest that SDX has a positive effect on ischemia-induced endothelial damage because of its antioxidant and antiapoptotic properties.

Relevance of dietary glycerophospholipids and sphingolipids to human health

Glycerophospholipids and sphingolipids participate in a variety of indispensable metabolic, neurological, and intracellular signaling processes. In this didactic paper we review the biological roles of phospholipids and try to unravel the precise nature of their putative healthful activities. We conclude that the biological actions of phospholipids activities potentially be nutraceutically exploited in the adjunct therapy of widely diffused pathologies such as neurodegeneration or the metabolic syndrome. As phospholipids can be recovered from inexpensive sources such as food processing by-products, ad-hoc investigation is warranted.

Mitochondrial Oxidative Stress, Mitochondrial DNA Damage and Their Role in Age-Related Vascular Dysfunction

The prevalence of cardiovascular diseases is significantly increased in the older population. Risk factors and predictors of future cardiovascular events such as hypertension, atherosclerosis, or diabetes are observed with higher frequency in elderly individuals. A major determinant of vascular aging is endothelial dysfunction, characterized by impaired endothelium-dependent signaling processes. Increased production of reactive oxygen species (ROS) leads to oxidative stress, loss of nitric oxide (^•NO) signaling, loss of endothelial barrier function and infiltration of leukocytes to the vascular wall, explaining the low-grade inflammation characteristic for the aged vasculature. We here discuss the importance of different sources of ROS for vascular aging and their contribution to the increased cardiovascular risk in the elderly population with special emphasis on mitochondrial ROS formation and oxidative damage of mitochondrial DNA. Also the interaction (crosstalk) of mitochondria with nicotinamide adenosine dinucleotide phosphate (NADPH) oxidases is highlighted. Current concepts of vascular aging, consequences for the development of cardiovascular events and the particular role of ROS are evaluated on the basis of cell culture experiments, animal studies and clinical trials. Present data point to a more important role of oxidative stress for the maximal healthspan (healthy aging) than for the maximal lifespan.

Involvement of neutral sphingomyelinase in the angiotensin II signaling pathway

The possibility that angiotensin II (ANG II) exerts its effects through the activation of neutral sphingomyelinase (nSMase) has not been tested in kidneys. The results of the present study provide evidence for the activity and expression of nSMase in rat kidneys. In isolated perfused rat kidney, ANG II-induced renal vasoconstriction was inhibited by GW4869, an inhibitor of nSMase. We used nSMase for investigating the signal transduction downstream of ceramide. nSMase constricted the renal vasculature. An inhibitor of ceramidase (CDase), N-oleoylethanolamine (OEA), enhanced either ANG II- or nSMase-induced renal vasoconstriction. To demonstrate the interaction between the nSMase and cytosolic phospholipase A2 (cPLA2) signal transduction pathways, we evaluated the response to nSMase in the presence and absence of inhibitors of arachidonic acid (AA) metabolism: arachidonyl trifluoromethyl ketone (AACOCF3), an inhibitor of cPLA2; 5,8,11,14-eicosatetraynoic acid (ETYA), an inhibitor of all AA pathways; indomethacin, an inhibitor of cyclooxygenase (COX); furegrelate, a thromboxane A2 (TxA2)-synthase inhibitor; and SQ29548 , a TxA2-receptor antagonist. In these experiments, the nSMase-induced renal vasoconstriction decreased. ANG II or nSMase was associated with an increase in the release of thromboxane B2 (TxB2) in the renal perfusate of isolated perfused rat kidney. In addition, the coexpression of the ceramide with cPLA2, was found in the smooth muscle layer of intrarenal vessels. Our results suggest that ANG II stimulates ceramide formation via the activation of nSMase; thus ceramide may indirectly regulate vasoactive processes that modulate the activity of cPLA2 and the release of TxA2.

Roles and regulation of neutral sphingomyelinase-2 in cellular and pathological processes

Our understanding of the functions of ceramide signaling has advanced tremendously over the past decade. In this review, we focus on the roles and regulation of neutral sphingomyelinase 2 (nSMase2), an enzyme that generates the bioactive lipid ceramide through the hydrolysis of the membrane lipid sphingomyelin. A large body of work has now implicated nSMase2 in a diverse set of cellular functions, physiological processes, and disease pathologies. We discuss different aspects of this enzyme's regulation from transcriptional, post-translational, and biochemical. Furthermore, we highlight nSMase2 involvement in cellular processes including inflammatory signaling, exosome generation, cell growth, and apoptosis, which in turn play important roles in pathologies such as cancer metastasis, Alzheimer's disease, and other organ systems disorders. Lastly, we examine avenues where targeted nSMase2-inhibition may be clinically beneficial in disease scenarios.

Serum profiling of healthy aging identifies phospho- and sphingolipid species as markers of human longevity

As centenarians well represent the model of healthy aging, there are many important implications in revealing the underlying molecular mechanisms behind such successful aging. By combining NMR metabonomics and shot-gun lipidomics in serum we analyzed metabolome and lipidome composition of a group of centenarians with respect to elderly individuals. Specifically, NMR metabonomics profiling of serum revealed that centenarians are characterized by a metabolic phenotype distinct from that of elderly subjects, in particular regarding amino acids and lipid species. Shot- gun lipidomics approach displays unique changes in lipids biosynthesis in centenarians, with 41 differently abundant lipid species with respect to elderly subjects. These findings reveal phospho/sphingolipids as putative markers and biological modulators of healthy aging, in humans. Considering the particular actions of these metabolites, these data are suggestive of a better counteractive antioxidant capacity and a well-developed membrane lipid remodelling process in the healthy aging phenotype.

Endothelial dysfunction is a potential contributor to multiple organ failure and mortality in aged mice subjected to septic shock: preclinical studies in a murine model of cecal ligation and puncture

INTRODUCTION

The goal of the current study was to investigate the effect of aging on the development of endothelial dysfunction in a murine model of sepsis, and to compare it with the effect of genetic deficiency of the endothelial isoform of nitric oxide synthase (eNOS).

METHODS

Cecal ligation and puncture (CLP) was used to induce sepsis in mice. Survival rates were monitored and plasma indices of organ function were measured. Ex vivo studies included the measurement of vascular function in thoracic aortic rings, assessment of oxidative stress/cellular injury in various organs and the measurement of mitochondrial function in isolated liver mitochondria.

RESULTS

eNOS deficiency and aging both exacerbated the mortality of sepsis. Both eNOS-deficient and aged mice exhibited a higher degree of sepsis-associated multiple organ dysfunction syndrome (MODS), infiltration of tissues with mononuclear cells and oxidative stress. A high degree of sepsis-induced vascular oxidative damage and endothelial dysfunction (evidenced by functional assays and multiple plasma markers of endothelial dysfunction) was detected in aortae isolated from both eNOS(-/-) and aged mice. There was a significant worsening of sepsis-induced mitochondrial dysfunction, both in eNOS-deficient mice and in aged mice. Comparison of the surviving and non-surviving groups of animals indicated that the severity of endothelial dysfunction may be a predictor of mortality of mice subjected to CLP-induced sepsis.

CONCLUSIONS

Based on the studies in eNOS mice, we conclude that the lack of endothelial nitric oxide production, on its own, may be sufficient to markedly exacerbate the severity of septic shock. Aging markedly worsens the degree of endothelial dysfunction in sepsis, yielding a significant worsening of the overall outcome. Thus, endothelial dysfunction may constitute an early predictor and independent contributor to sepsis-associated MODS and mortality in aged mice.

The role of oxidative stress and inflammation in cardiovascular aging

Age is an independent risk factor of cardiovascular disease, even in the absence of other traditional factors. Emerging evidence in experimental animal and human models has emphasized a central role for two main mechanisms of age-related cardiovascular disease: oxidative stress and inflammation. Excess reactive oxygen species (ROS) and superoxide generated by oxidative stress and low-grade inflammation accompanying aging recapitulate age-related cardiovascular dysfunction, that is, left ventricular hypertrophy, fibrosis, and diastolic dysfunction in the heart as well as endothelial dysfunction, reduced vascular elasticity, and increased vascular stiffness. We describe the signaling involved in these two main mechanisms that include the factors NF-κB, JunD, p66^Shc, and Nrf2. Potential therapeutic strategies to improve the cardiovascular function with aging are discussed, with a focus on calorie restriction, SIRT1, and resveratrol.

Age-related remodeling of small arteries is accompanied by increased sphingomyelinase activity and accumulation of long-chain ceramides

The structure and function of large arteries alters with age leading to increased risk of cardiovascular disease. Age‐related large artery remodeling and arteriosclerosis is associated with increased collagen deposition, inflammation, and endothelial dysfunction. Bioactive sphingolipids are known to regulate these processes, and are also involved in aging and cellular senescence. However, less is known about age‐associated alterations in small artery morphology and function or whether changes in arterial sphingolipids occur in aging. We show that mesenteric small arteries from old sheep have increased lumen diameter and media thickness without a change in media to lumen ratio, indicative of outward hypertrophic remodeling. This remodeling occurred without overt changes in blood pressure or pulse pressure indicating it was a consequence of aging per se. There was no age‐associated change in mechanical properties of the arteries despite an increase in total collagen content and deposition of collagen in a thickened intima layer in arteries from old animals. Analysis of the sphingolipid profile showed an increase in long‐chain ceramide (C14–C20), but no change in the levels of sphingosine or sphingosine‐1‐phosphate in arteries from old compared to young animals. This was accompanied by a parallel increase in acid and neutral sphingomyelinase activity in old arteries compared to young. This study demonstrates remodeling of small arteries during aging that is accompanied by accumulation of long‐chain ceramides. This suggests that sphingolipids may be important mediators of vascular aging.

In this study, we have investigated remodeling of small arteries in a large animal model of aging, the sheep. We show that there is age‐related formation of neointima and increased collagen deposition that is accompanied by changes in sphingolipid metabolism resulting in ceramide accumulation in the tissues. These are the first data implicating sphingolipids as important mediators of vascular aging in small arteries. Given that aging is a major risk factor for cardiovascular disease, our study opens a new area for further research into the mechanisms that underlie vascular remodeling in aging.

Hydroxytyrosol attenuates tunicamycin-induced endoplasmic reticulum stress in human hepatocarcinoma cells

SCOPE

Hydroxytyrosol (HT) is a phenolic compound peculiarly abundant in olives and it is being recognized as a protector of LDL from oxidation. In addition to lipid oxidation, one emerging risk factor for cardiovascular disease is ER stress. We tested the effect of HT on the modulation of ER stress in HepG2 cells.

METHODS AND RESULTS

HepG2 cells were treated with 1 μM and 5 μM of HT and 100 μM lipoic acid (LA) and glutathione-ethyl ester (GSH), for 24 h. Induction of the unfolded protein response (UPR) was initiated by treatment with 2 μg/mL tunicamycin for 4 h. Real time RT-PCR analyses followed by Western blot and ELISA of different ER stress markers revealed that the protective activities of HT were superior to those of two known thiolic antioxidants, i.e., LA and GSH.

CONCLUSION

Mounting evidence indicates the ER as an important target of dietary or pharmacological intervention. In this paper, we report the modulatory activities of physiological concentrations of HT toward ER stress and we shed some light on pathways alternative to the well-known antioxidant mechanisms, through which olive oil phenolics modulate cell signaling and could impact cardiovascular health and degenerative diseases.

Glutathione peroxidase-1 deficiency potentiates dysregulatory modifications of endothelial nitric oxide synthase and vascular dysfunction in aging

Recently, we demonstrated that gene ablation of mitochondrial manganese superoxide dismutase and aldehyde dehydrogenase-2 markedly contributed to age-related vascular dysfunction and mitochondrial oxidative stress. The present study has sought to investigate the extent of vascular dysfunction and oxidant formation in glutathione peroxidase-1-deficient (GPx-1(-/-)) mice during the aging process with special emphasis on dysregulation (uncoupling) of the endothelial NO synthase. GPx-1(-/-) mice on a C57 black 6 (C57BL/6) background at 2, 6, and 12 months of age were used. Vascular function was significantly impaired in 12-month-old GPx-1(-/-) -mice as compared with age-matched controls. Oxidant formation, detected by 3-nitrotyrosine staining and dihydroethidine-based fluorescence microtopography, was increased in the aged GPx-1(-/-) mice. Aging per se caused a substantial protein kinase C- and protein tyrosine kinase-dependent phosphorylation as well as S-glutathionylation of endothelial NO synthase associated with uncoupling, a phenomenon that was more pronounced in aged GPx-1(-/-) mice. GPx-1 ablation increased adhesion of leukocytes to cultured endothelial cells and CD68 and F4/80 staining in cardiac tissue. Aged GPx-1(-/-) mice displayed increased oxidant formation as compared with their wild-type littermates, triggering redox-signaling pathways associated with endothelial NO synthase dysfunction and uncoupling. Thus, our data demonstrate that aging leads to decreased NO bioavailability because of endothelial NO synthase dysfunction and uncoupling of the enzyme leading to endothelial dysfunction, vascular remodeling, and promotion of adhesion and infiltration of leukocytes into cardiovascular tissue, all of which was more prominent in aged GPx-1(-/-) mice.