Grape seed proanthocyanidin extracts enhance endothelial nitric oxide synthase expression through 5'-AMP activated protein kinase/Surtuin 1-Krüpple like factor 2 pathway and modulate blood pressure in ouabain induced hypertensive rats

Sodium pump subunit NKAα1 protects against diabetic endothelial dysfunction by inhibiting ferroptosis through the autophagy-lysosome degradation of ACSL4

The sodium pump Na+/K+-ATPase (NKA), an enzyme ubiquitously expressed in various tissues and cells, is a critical player in maintaining cellular ion homeostasis. Dysregulation of α1 subunit of NKA (NKAα1) has been associated with cardiovascular and metabolic disorders, yet the exact role of NKAα1 in diabetes-induced endothelial malfunction remains incompletely understood. The NKAα1 expression and NKA activity were examined in high-glucose (HG)-exposed endothelial cells (ECs) and mouse aortae, as well as in high-fat-diet (HFD)-fed mice. Acetylcholine (Ach) was utilised to assess endothelium-dependent relaxation (EDR) in isolated mouse aortae. We found that both NKAα1 protein and mRNA levels were significantly downregulated in the aortae of HFD-fed mice, and HG-incubated mouse aortae and ECs. Gain- and loss-of-function experiments revealed that NKAα1 preserves EDR by mitigating oxidative/nitrative stresses in ECs. Overexpression of NKAα1 facilitated EC viability, migration, and angiogenesis by inhibiting the overproduction of superoxide and peroxynitrite. Mechanistically, dysfunctional NKAα1 impaired autophagy process, and prevented the transfer of acyl-CoA synthetase long-chain family member 4 (ACSL4) to the lysosome for degradation, thereby resulting in lipid peroxidation and ferroptosis in ECs. Induction of ferroptosis and inhibition of the autophagy-lysosome pathway blocked the protective effects of NKAα1 on EDR. Eventually, we identified Hamaudol as a potent activator of NKAα1 by restraining the phosphorylation and endocytosis of NKAα1, restoring EDR in obese diabetic mice. Overall, NKAα1 facilitates the autophagic degradation of ACSL4 via the lysosomal pathway, preventing ferroptosis and oxidative/nitrative stress in ECs. NKAα1 may serve as an attractive candidate for the management of vascular disorders associated with diabetes. KEY POINTS: NKAα1 downregulation impairs endothelial function in diabetes by promoting oxidative/nitrative stress and ferroptosis. NKAα1 supports lysosomal degradation of ACSL4 via autophagy, preventing lipid peroxidation and ferroptosis. Hamaudol, an activator of NKAα1, restores endothelial relaxation in diabetic mice by inhibiting NKAα1 phosphorylation and endocytosis.

Natural Products to Promote Vascular Health

Maintaining good vascular health is a major component in healthy ageing as it reduces the risk of cardiovascular diseases. Endothelial dysfunction, in particular, is a key mechanism in the development of major cardiovascular diseases including hypertension, atherosclerosis and diabetes. Recently, endothelial senescence has emerged as a pivotal early event in age-related endothelial dysfunction. Endothelial function is characterized by an imbalance between the endothelial formation of vasoprotective mechanisms, including the formation of nitric oxide (NO) and endothelium-dependent hyperpolarization responses, and an increased level of oxidative stress involving several pro-oxidant enzymes such as NADPH oxidases and, often also, the appearance of cyclooxygenase-derived vasoconstrictors. Pre-clinical studies have indicated that natural products, in particular several polyphenol-rich foods, can trigger activating pathways in endothelial cells promoting an increased formation of NO and endothelium-dependent hyperpolarization. In addition, some can even exert beneficial effects on endothelial senescence. Moreover, some of these products have been associated with the prevention and/or improvement of established endothelial dysfunction in several experimental models of cardiovascular diseases and in humans with cardiovascular diseases. Therefore, intake of certain natural products, such as dietary and plant-derived polyphenol-rich products, appears to be an attractive approach for a healthy vascular system in ageing.

Decoding the anti-hypertensive mechanism of α-mangostin based on network pharmacology, molecular docking and experimental validation

BACKGROUND

Hypertension is a leading risk factor for disability and deaths worldwide. Evidence indicates that alpha-mangostin(α-MG) can reduce blood pressure and improve target organ damage. Nonetheless, its pharmacological targets and potential mechanisms of action remain inadequately elucidated.

METHOD

We used SwissTargetPrediction to identify α-MG's drug targets and DisGeNET, GeneCards, CTD, and GEO databases for hypertension-related targets, and then determined antihypertensive therapeutic targets of α-MG by intersecting these targets. GO functional enrichment analysis, KEGG pathway analysis, and disease association analysis were conducted using the DAVID database and R package "clusterprofile", visualized with Cytoscape software. The binding affinity of α-MG to identified targets was confirmed through molecular docking using Autodock Vina v.1.2.2 software. The impact of α-MG on target genes was validated using an Angiotensin II-induced hypertensive mouse model and RT-qPCR.

RESULTS

A total of 51 potential antihypertensive therapeutic targets for α-MG were identified by intersecting 109 drug targets with 821 disease targets. Furthermore, 10 cellular component terms, 10 disease terms, and the top 20 enriched biological processes, molecular functions, and KEGG pathways related to α-MG's antihypertensive effects were documented. Molecular docking studies indicated a strong binding affinity of α-MG with the HSP90AA1 domain. In Ang II-induced hypertensive mice aorta, treatment with α-MG effectively reversed the aberrant mRNA expression of TNF, HSP90AA1, NFKB1, PPARG, SIRT1, PTGS2, and RELA.

CONCLUSION

Our analyses showed that TNF, HSP90AA1, NFKB1, PPARG, SIRT1, PTGS2, and RELA might be α-MG's potential therapeutic targets for hypertension, laying groundwork for further investigation into its pharmacological mechanisms and clinical uses.

Integrated analysis of the lncRNA-associated competing endogenous RNA network in salt sensitivity of blood pressure

Accumulating evidence showed that competing endogenous RNA (ceRNA) mechanism plays a pivotal role in salt sensitivity of blood pressure (SSBP). We constructed a ceRNA network based on SSBP-related differently expressed lncRNAs (2), mRNAs (73) and miRNAs (18). Bioinformatic analyses were utilized to analyze network and found network genes participate in biological pathways related to SSBP pathogenesis such as regulation of nitric oxide biosynthetic process (GO:0045,428) and cellular response to cytokine stimulus (GO:0071,345). Fourteen candidate ceRNA pathways were selected from network to perform qRT-PCR validation and found nine RNAs (KCNQ1OT1, SLC8A1-AS1, IL1B, BCL2L11, KCNJ15, CX3CR1, KLF2, hsa-miR-362-5p and hsa-miR-423-5p) differently expressed between salt-sensitive (SS) and salt-resistant (SR) groups (P < 0.05). Four ceRNA pathways were further validated by luciferase reporter assay and found KCNQ1OT1→hsa-miR-362-5p/hsa-miR-423-5p→IL1B pathways may influence the pathogenic mechanism of SS. Our findings suggested the ceRNA pathway and network may affect SS occurrence mainly through endothelial dysfunction and inflammatory activation.

Bioactive molecules from terrestrial and seafood resources in hypertension treatment: focus on molecular mechanisms and targeted therapies

Hypertension (HTN), a complex cardiovascular disease (CVD), significantly impacts global health, prompting a growing interest in complementary and alternative therapeutic approaches. This review article seeks to provide an up-to-date and thorough summary of modern therapeutic techniques for treating HTN, with an emphasis on the molecular mechanisms of action found in substances found in plants, herbs, and seafood. Bioactive molecules have been a significant source of novel therapeutics and are crucial in developing and testing new HTN remedies. Recent advances in science have made it possible to understand the complex molecular mechanisms underlying blood pressure (BP)-regulating effects of these natural substances better. Polyphenols, flavonoids, alkaloids, and peptides are examples of bioactive compounds that have demonstrated promise in influencing several pathways involved in regulating vascular tone, reducing oxidative stress (OS), reducing inflammation, and improving endothelial function. The article explains the vasodilatory, diuretic, and renin-angiotensin-aldosterone system (RAAS) modifying properties of vital plants such as garlic and olive leaf. Phytochemicals from plants are the primary in traditional drug development as models for novel antihypertensive drugs, providing diverse strategies to combat HTN due to their biological actions. The review also discusses the functions of calcium channel blockers originating from natural sources, angiotensin-converting enzyme (ACE) inhibitors, and nitric oxide (NO) donors. Including seafood components in this study demonstrates the increased interest in using bioactive chemicals originating from marine sources to treat HTN. Omega-3 fatty acids, peptides, and minerals obtained from seafood sources have anti-inflammatory, vasodilatory, and antioxidant properties that improve vascular health and control BP. Overall, we discussed the multiple functions of bioactive molecules and seafood components in the treatment of HTN.

The effect of whole grape products on blood pressure and vascular function: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIMS

Grape consumption-associated improvements in cardiovascular health have received significant attention over the last few years; however, major gaps have remained in the meta-evidence related to this topic. This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to explore the effect of whole grapes and its products on blood pressure, endothelial function, heart rate, and pulse rate.

METHODS AND RESULTS

Four database (PubMed, Scopus, Web of Sciences, and the Cochrane Library) were searched until the 14th of January 2022. The pooled effect size of interested outcomes was calculated using the random-effects model. Thirty eligible RCTs were identified. Pooled results indicated that compared to the control group, consumption of grape products significantly decreased systolic blood pressure (SBP) (WMD = -3.17 mmHg; 95% CI: -5.36, -0.99 mmHg; P = 0.004; I2 = 64%; P-heterogeneity<0.001); while, vascular cell adhesion molecule-1 (VCAM-1) increased (WMD = 34.11 ng/ml; 95% CI: 0.98, 67.25 ng/ml; P = 0.04; I2 = 2%; P-heterogeneity = 0.4). Although, the certainty of evidence was low and very low, respectively. No significant effect was observed on diastolic blood pressure, endothelial function, heart rate, pulse rate, and soluble intercellular adhesion molecule-1 (sICAM-1). In a subgroup analysis, consumption of whole grape products (raisin and grape powder) induced a significant decrease in SBP (WMD = -2.69 mmHg; 95% CI: -4.81, -0.57; P = 0.01; I2 = 18.1%; P-heterogeneity < 0.001), while grape juice did not.

CONCLUSION

The low certainty of evidence from RCTs revealed that consumption of grape products, especially in whole forms, resulted in a small reduction of SBP but did not influence other markers of cardiovascular health.

PROSPERO REGISTRATION CODE

CRD42022379231.

Oxidative Stress and MicroRNAs in Endothelial Cells under Metabolic Disorders

Reactive oxygen species (ROS) are radical oxygen intermediates that serve as important second messengers in signal transduction. However, when the accumulation of these molecules exceeds the buffering capacity of antioxidant enzymes, oxidative stress and endothelial cell (EC) dysfunction occur. EC dysfunction shifts the vascular system into a pro-coagulative, proinflammatory state, thereby increasing the risk of developing cardiovascular (CV) diseases and metabolic disorders. Studies have turned to the investigation of microRNA treatment for CV risk factors, as these post-transcription regulators are known to co-regulate ROS. In this review, we will discuss ROS pathways and generation, normal endothelial cell physiology and ROS-induced dysfunction, and the current knowledge of common metabolic disorders and their connection to oxidative stress. Therapeutic strategies based on microRNAs in response to oxidative stress and microRNA's regulatory roles in controlling ROS will also be explored. It is important to gain an in-depth comprehension of the mechanisms generating ROS and how manipulating these enzymatic byproducts can protect endothelial cell function from oxidative stress and prevent the development of vascular disorders.

Oligomeric Proanthocyanidins: An Updated Review of Their Natural Sources, Synthesis, and Potentials

Oligomeric Proanthocyanidins (OPCs), as a class of compounds widely found in plants, are particularly abundant in grapes and blueberries. It is a polymer comprising many different monomers, such as catechins and epicatechins. The monomers are usually linked to each other by two types of links, A-linkages (C-O-C) and B-linkages (C-C), to form the polymers. Numerous studies have shown that compared to high polymeric procyanidins, OPCs exhibit antioxidant properties due to the presence of multiple hydroxyl groups. This review describes the molecular structure and natural source of OPCs, their general synthesis pathway in plants, their antioxidant capacity, and potential applications, especially the anti-inflammatory, anti-aging, cardiovascular disease prevention, and antineoplastic functions. Currently, OPCs have attracted much attention, being non-toxic and natural antioxidants of plant origin that scavenge free radicals from the human body. This review would provide some references for further research on the biological functions of OPCs and their application in various fields.

Novel pathophysiological roles of α-synuclein in age-related vascular endothelial dysfunction

Although α-synuclein (SNCA) is a well-known pathological molecule involved in synucleinopathy in neurons, its physiological roles remain largely unknown. We reported that serum SNCA levels have a close inverse correlation with blood pressure and age, which indicates the involvement of SNCA in age-related endothelial dysfunction. Therefore, this study aimed to elucidate the molecular functions of SNCA in the endothelium. We confirmed that SNCA was expressed in and secreted from endothelial cells (ECs). Exogenous treatment with recombinant SNCA (rSNCA) activated the Akt-eNOS axis and increased nitric oxide production in ECs. Treatment with rSNCA also suppressed TNF-α- and palmitic acid-induced NF-κB activation, leading to the suppression of VCAM-1 upregulation and restoration of eNOS downregulation in ECs. As for endogenous SNCA expression, replicative senescence resulted in the attenuation of SNCA expression in cultured ECs, similar to the effects of physiological aging on mice aortas. The siRNA-mediated silencing of SNCA consistently resulted in senescent phenotypes, such as eNOS downregulation, increased β-gal activity, decreased Sirt1 expression, and increased p53 expression, in ECs. Ex vivo assessment of endothelial functions using aortic rings revealed impaired endothelium-dependent acetylcholine-induced relaxation in SNCA knockout (KO) mice. Furthermore, SNCA KO mice, especially those on a high-fat diet, displayed elevated blood pressure compared with wild-type mice; this could be eNOS dysfunction-dependent because of the lower difference caused by L-NAME administration. These results indicate that exogenous and endogenous SNCA in ECs might physiologically maintain vascular integrity, and age-related endothelial dysfunction might be partially ascribed to loss-of-function of SNCA in ECs.

Proanthocyanidins Restore the Metabolic Diurnal Rhythm of Subcutaneous White Adipose Tissue According to Time-Of-Day Consumption

Consumption of grape seed proanthocyanidin extract (GSPE) has beneficial effects on the functionality of white adipose tissue (WAT). However, although WAT metabolism shows a clear diurnal rhythm, whether GSPE consumption could affect WAT rhythmicity in a time-dependent manner has not been studied. Ninety-six male Fischer rats were fed standard (STD, two groups) or cafeteria (CAF, four groups) diet for 9 weeks (n = 16 each group). From week 6 on, CAF diet animals were supplemented with vehicle or 25 mg GSPE/kg of body weight either at the beginning of the light/rest phase (ZT0) or at the beginning of the dark/active phase (ZT12). The two STD groups were also supplemented with vehicle at ZT0 or ZT12. In week 9, animals were sacrificed at 6 h intervals (n = 4) to analyze the diurnal rhythms of subcutaneous WAT metabolites by nuclear magnetic resonance spectrometry. A total of 45 metabolites were detected, 19 of which presented diurnal rhythms in the STD groups. Although most metabolites became arrhythmic under CAF diet, GSPE consumption at ZT12, but not at ZT0, restored the rhythmicity of 12 metabolites including compounds involved in alanine, aspartate, and glutamate metabolism. These results demonstrate that timed GSPE supplementation may restore, at least partially, the functional dynamics of WAT when it is consumed at the beginning of the active phase. This study opens an innovative strategy for time-dependent polyphenol treatment in obesity and metabolic diseases.

Ferulic acid and berberine, via Sirt1 and AMPK, may act as cell cleansing promoters of healthy longevity

Ferulic acid, a bacterial metabolite of anthocyanins, seems likely to be a primary mediator of the health benefits associated with anthocyanin-rich diets, and has long been employed in Chinese cardiovascular medicine. In rodent studies, it has exerted wide-ranging antioxidant and anti-inflammatory effects, the molecular basis of which remains rather obscure. However, recent studies indicate that physiologically relevant concentrations of ferulic acid can boost expression of Sirt1 at mRNA and protein levels in a range of tissues. Sirt1, a class III deacetylase, functions to detect a paucity of oxidisable substrate, and in response works in various ways to promote cellular survival and healthful longevity. Sirt1 promotes ‘cell cleansing’ and cell survival by boosting autophagy, mitophagy, mitochondrial biogenesis, phase 2 induction of antioxidant enzymes via Nrf2, and DNA repair—while inhibiting NF-kB-driven inflammation, apoptosis, and cellular senescence, and boosting endothelial expression of the protective transcription factor kruppel-like factor 2. A deficit of the latter appears to mediate the endothelial toxicity of the SARS-CoV-2 spike protein. Ferulic acid also enhances the activation of AMP-activated kinase (AMPK) by increasing expression and activity of its activating kinase LKB1—whereas AMPK in turn amplifies Sirt1 activity by promoting induction of nicotinamide phosphoribosyltranferase, rate-limiting for generation of Sirt1’s obligate substrate NAD+. Curiously, AMPK acts by independent mechanisms to potentiate many of the effects mediated by Sirt1. Hence, it is proposed that ferulic acid may exert complementary or synergistic health-promoting effects when used in conjunction with clinically useful AMPK activators, such as the nutraceutical berberine. Additional nutraceuticals which might have potential for amplifying certain protective effects of ferulic acid/berberine are also discussed.

Coenzyme Q10 deficiency can be expected to compromise Sirt1 activity

For reasons that remain unclear, endogenous synthesis and tissue levels of coenzyme Q10 (CoQ10) tend to decline with increasing age in at least some tissues. When CoQ10 levels are sufficiently low, this compromises the efficiency of the mitochondrial electron transport chain, such that production of superoxide by site 2 increases and the rate of adenosine triphosphate production declines. Moreover, CoQ10 deficiency can be expected to decrease activities of Sirt1 and Sirt3 deacetylases, believed to be key determinants of health span. Reduction of the cytoplasmic and mitochondrial NAD+/NADH ratio consequent to CoQ10 deficit can be expected to decrease the activity of these deacetylases by lessening availability of their obligate substrate NAD+ The increased oxidant production induced by CoQ10 deficiency can decrease the stability of Sirt1 protein by complementary mechanisms. And CoQ10 deficiency has also been found to lower mRNA expression of Sirt1. An analysis of the roles of Sirt1/Sirt3 in modulation of cellular function helps to rationalise clinical benefits of CoQ10 supplementation reported in heart failure, hypertension, non-alcoholic fatty liver disease, metabolic syndrome and periodontal disease. Hence, correction of CoQ10 deficiency joins a growing list of measures that have potential for amplifying health protective Sirt1/Sirt3 activities.

Nutraceutical and Dietary Strategies for Up-Regulating Macroautophagy

Macroautophagy is a "cell cleansing" process that rids cells of protein aggregates and damaged organelles that may contribute to disease pathogenesis and the dysfunctions associated with aging. Measures which boost longevity and health span in rodents typically up-regulate macroautophagy, and it has often been suggested that safe strategies which can promote this process in humans may contribute to healthful aging. The kinase ULK1 serves as a trigger for autophagy initiation, and the transcription factors TFEB, FOXO1, ATF4 and CHOP promote expression of a number of proteins which mediate macroautophagy. Nutraceutical or dietary measures which stimulate AMPK, SIRT1, eIF5A, and that diminish the activities of AKT and mTORC1, can be expected to boost the activities of these pro-autophagic factors. The activity of AMPK can be stimulated with the phytochemical berberine. SIRT1 activation may be achieved with a range of agents, including ferulic acid, melatonin, urolithin A, N1-methylnicotinamide, nicotinamide riboside, and glucosamine; correction of ubiquinone deficiency may also be useful in this regard, as may dietary strategies such as time-restricted feeding or intermittent fasting. In the context of an age-related decrease in cellular polyamine levels, provision of exogenous spermidine can boost the hypusination reaction required for the appropriate post-translational modification of eIF5A. Low-protein plant-based diets could be expected to increase ATF4 and CHOP expression, while diminishing IGF-I-mediated activation of AKT and mTORC1. Hence, practical strategies for protecting health by up-regulating macroautophagy may be feasible.

A comprehensive review of Sirtuins: With a major focus on redox homeostasis and metabolism

Sirtuins are Class III protein deacetylases with seven conserved isoforms. In general, Sirtuins are highly activated under cellular stress conditions in which NAD⁺ levels are increased. Nevertheless, regulation of Sirtuins extends far beyond the influences of cellular NAD⁺/NADH ratio and a rapidly expanding body of evidence currently suggests that their expression and catalytic activity are highly kept under control at multiple levels by various factors and processes. Owing to their intrinsic ability to enzymatically target various intracellular proteins, Sirtuins are prominently involved in the regulation of fundamental biological processes including inflammation, metabolism, redox homeostasis, DNA repair and cell proliferation and senescence. In fact, Sirtuins are well established to regulate and reprogram different redox and metabolic pathways under both pathological and physiological conditions. Therefore, alterations in Sirtuin levels can be a pivotal intermediary step in the pathogenesis of several disorders. This review first highlights the mechanisms involved in the regulation of Sirtuins and further summarizes the current findings on the major functions of Sirtuins in cellular redox homeostasis and bioenergetics (glucose and lipid metabolism).

Changes in arterial blood pressure caused by long-term administration of grape seed proanthocyanidins in rats with established hypertension

The development of hypertension (HTN) in cafeteria (CAF) diet-fed rats was demonstrated to be attenuated after grape seed proanthocyanidin extract (GSPE) administration. However, the long-term antihypertensive effect of GSPE in animals with established HTN has not been investigated. Thus, the aim of this study was to evaluate if GSPE shows a blood pressure-lowering effect in hypertensive rats after its administration for 3 weeks. Wistar rats were fed a standard or CAF diet for 12 weeks, and during the last 3 weeks, animals were administered vehicle, captopril or a low dose of GSPE (25 mg per kg body weight, bw). Both systolic and diastolic blood pressure (SBP and DBP) were monitored weekly. The liver reduced glutathione (GSH) levels, plasma angiotensin converting enzyme activity and endothelial gene expression of eNOS, KLF-2, Sirt-1, NOX4 and ET-1 were studied at the end-point. The results demonstrated that 3 weeks of CAF diet administration with 25 mg per kg bw GSPE significantly reduced SBP and DBP in hypertensive rats. GSPE induced the upregulation of Sirt-1 gene expression and downregulated the vasoconstrictor ET-1, suggesting the vasoprotective effect of GSPE and increased the antioxidant GSH activity. The administration of 25 mg per kg bw GSPE for 3 weeks significantly reduced BP in CAF diet fed animals with established HTN.

Betulinic Acid Induces eNOS Expression via the AMPK-Dependent KLF2 Signaling Pathway

Betulinic acid (BA) is a natural pentacyclic triterpenoid with protective effects against inflammation, metabolic diseases, and cardiovascular diseases. We have previously shown that BA prevents endothelial dysfunction by increasing nitric oxide (NO) synthesis through activating endothelial nitric oxide synthase (eNOS) in human endothelial cells. However, the effect of BA on eNOS expression remains unclear. Thus, the aim of our study was to investigate the intracellular pathways associated with the effect of BA to regulate eNOS expression in human endothelial cells. BA significantly increased eNOS expression in a time- and concentration-dependent manner. Additionally, BA upregulated the expression of the transcription factor KLF2, which is known to regulate eNOS expression. KLF2 silencing in human endothelial cells attenuated the ability of BA to upregulate eNOS. BA also increased levels of intracellular Ca²⁺, activating CaMKKβ, CaMKIIα, and AMPK. Inhibition of the TRPC calcium channel abolished BA-mediated effects on intracellular Ca²⁺ levels. Moreover, BA increased the phosphorylation levels of ERK5, HDAC5, and MEF2C. Pretreatment of cells with compound C (AMPK inhibitor), LMK235 (HDAC5 inhibitor), and XMD8-92 (ERK5 inhibitor) attenuated the BA-induced eNOS expression. Collectively, these findings suggest that BA induces eNOS expression by activating the HDAC5/ERK5/KLF2 pathway in endothelial cells. The data presented here provide strong evidence supporting the use of BA to prevent endothelial dysfunction and treat vascular diseases, such as atherosclerosis.

Grape Extract from Chardonnay Seeds Restores Deoxycorticosterone Acetate-Salt-Induced Endothelial Dysfunction and Hypertension in Rats

Grape extract (GE), which contains various polyphenolic compounds, exerts protective effects against lifestyle-related diseases, such as diabetes and hypertension. We pharmacologically investigated whether dietary supplements with an extract from Chardonnay exerted antihypertensive effects in deoxycorticosterone acetate (DOCA)-salt-induced hypertensive rats. GE increased nitric oxide (NO) production by activating the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in cultured endothelial cells and induced vasorelaxation in the aorta and mesenteric artery via the same pathway. The development and progression of hypertension by the DOCA-salt treatment was significantly inhibited in GE-fed rats. Reduced vasoreactive responses to acetylcholine in the aorta of DOCA-salt rats were significantly ameliorated by the GE diet. Dietary GE supplements slightly diminished vascular superoxide anion production induced by the DOCA-salt treatment. On the other hand, dietary GE supplements had no effect on the progression of hypertension in rats in which NO synthase was pharmacologically and chronically suppressed. In addition, the oral administration of GE for 5 d in healthy rats enhanced endothelial NO synthase (eNOS) gene expression and vascular reactivity to acetylcholine in the aorta. Thus, GE has endothelium-dependent vasorelaxant properties that are mediated by the activation of endothelial NO synthase via the PI3K/Akt pathway, and this mechanism is conducive to the antihypertensive effects of GE observed in DOCA-salt-treated rats.

Anthocyanidin Extract from Summer-black-grape Affects the Expression of Ki-67 in Testis, Ovary of D-Galactose-induced Aging Mice

The aim of this work was to analyze the expression of Ki-67 in ovary, testis of aging mice with anthocyanidin extract from Summer-black-grape. ICR mice (the aging group and the anthocyanidin-groups (50 mg/kg/D-group, 75 mg/kg/D-group and 100 mg/kg/D-group) were employed to evaluate the effect of grape anthocyanidin on reproductive system. The results showed that the anthocyanidin had strong scavenging ability for free radicals, the level of oxidation in serum of mice treated with anthocyanidin was low, and the pathological changes were not obvious. In the anthocyanidin group, the Ki-67 positive particles in the testis and ovary tissue were significantly decreased. The anthocyanidin of Summer-black-grape reduces the expression of Ki-67 protein in the testis or ovary of aging mice. In gonadal cells of aging mice, the anthocyanidin were shown protective effect in the proliferation.

Polyphenols by Generating H2O2, Affect Cell Redox Signaling, Inhibit PTPs and Activate Nrf2 Axis for Adaptation and Cell Surviving: In Vitro, In Vivo and Human Health

Human health benefits from different polyphenols molecules consumption in the diet, derived mainly by their common activities in the gastrointestinal tract and at the level of blood micro-capillary. In the stomach, intestine and colon, polyphenols act as reducing agents preventing lipid peroxidation, generation and absorption of AGEs/ALEs (advanced glycation end products/advanced lipid oxidation end products) and postprandial oxidative stress. The low absorption of polyphenols in blood does not support their activity as antioxidants and their mechanism of activity is not fully understood. The results are from in vitro, animal and human studies, detected by relevant oxidative stress markers. The review carries evidences that polyphenols, by generating H₂O₂ at nM concentration, exogenous to cells and organs, act as activators of signaling factors increasing cell Eustress. When polyphenols attain high concentration in the blood system, they generate H₂O₂ at µM concentration, acting as cytotoxic agents and Distress. Pre-treatment of cells or organisms with polyphenols, by generating H₂O₂ at low levels, inhibits cellular PTPs (protein tyrosine phosphatases), inducing cell signaling through transcription of the Nrf2 (nuclear factor erythroid 2-related factor 2) axis of adaptation and protection to oxidation stress. Polyphenols ingestion at the right amount and time during the meal acts synergistically at the level of the gastrointestinal tract (GIT) and blood system, for keeping the redox homeostasis in our organism and better balancing human health.

Resveratrol and the Interaction between Gut Microbiota and Arterial Remodelling

Arterial remodelling refers to the alteration in the structure of blood vessel that contributes to the progression of hypertension and other cardiovascular complications. Arterial remodelling is orchestrated by the crosstalk between the endothelium and vascular smooth muscle cells (VSMC). Vascular inflammation participates in arterial remodelling. Resveratrol is a natural polyphenol that possesses anti-oxidant and anti-inflammatory properties and has beneficial effects in both the endothelium and VSMC. Resveratrol has been studied for the protective effects in arterial remodelling and gut microbiota, respectively. Gut microbiota plays a critical role in the immune system and inflammatory processes. Gut microbiota may also regulate vascular remodelling in cardiovascular complications via affecting endothelium function and VSMC proliferation. Currently, there is new evidence showing that gut microbiota regulate the proliferation of VSMC and the formation of neointimal hyperplasia in response to injury. The change in population of the gut microbiota, as well as their metabolites (e.g., short-chain fatty acids) could critically contribute to VSMC proliferation, cell cycle progression, and migration. Recent studies have provided strong evidence that correlate the effects of resveratrol in arterial remodelling and gut microbiota. This review aims to summarize recent findings on the resveratrol effects on cardiovascular complications focusing on arterial remodelling and discuss the possible interactions of resveratrol and the gut microbiota that modulate arterial remodelling.

The roles of gut microbiota and circadian rhythm in the cardiovascular protective effects of polyphenols

Polyphenols are secondary metabolites of plants that have been widely studied for their health benefits as antioxidants. In the last decade, several clinical trials and epidemiological studies have shown that long‐term consumption of polyphenol‐rich diet protects against chronic diseases such as cancers and cardiovascular diseases. Current cardiovascular studies have also suggested an important role of gut microbiota and circadian rhythm in the pathogenesis metabolic and cardiovascular diseases. It is known that polyphenols can modulate the composition of core gut microbiota and interact with circadian clocks. In this article, we summarize recent findings, review the molecular mechanisms and the potential of polyphenols as dietary supplements for regulating gut microbiota and circadian rhythms, and discuss future research directions.

Linked Articles

This article is part of a themed section on The Pharmacology of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.6/issuetoc

Targeting Inflammation by Flavonoids: Novel Therapeutic Strategy for Metabolic Disorders

A balanced metabolic profile is essential for normal human physiological activities. Disproportions in nutrition give rise to imbalances in metabolism that are associated with aberrant immune function and an elevated risk for inflammatory-associated disorders. Inflammation is a complex process, and numerous mediators affect inflammation-mediated disorders. The available clinical modalities do not effectively address the underlying diseases but rather relieve the symptoms. Therefore, novel targeted agents have the potential to normalize the metabolic system and, thus, provide meaningful therapy to the underlying disorder. In this connection, polyphenols, the well-known and extensively studied phytochemical moieties, were evaluated for their effective role in the restoration of metabolism via various mechanistic signaling pathways. The various flavonoids that we observed in this comprehensive review interfere with the metabolic events that induce inflammation. The mechanisms via which the polyphenols, in particular flavonoids, act provide a promising treatment option for inflammatory disorders. However, detailed clinical studies of such molecules are required to decide their clinical fate.

The Role of Sirtuin1 in Regulating Endothelial Function, Arterial Remodeling and Vascular Aging

Sirtuin1 (SIRT1), which belongs to a highly conserved family of protein deacetylase, is one of the best-studied sirtuins. SIRT1 is involved in a variety of biological processes, including energy metabolism, cell proliferation and survival, chromatin dynamics, and DNA repair. In the vasculature, SIRT1 is ubiquitously expressed in endothelial cells, smooth muscle cells, and perivascular adipose tissues (PVAT). Endothelial SIRT1 plays a unique role in vasoprotection by regulating a large variety of proteins, including endothelial nitric oxide synthase (eNOS). In endothelial cells, SIRT1 and eNOS regulate each other synergistically through positive feedback mechanisms for the maintenance of endothelial function. Recent studies have shown that SIRT1 plays a vital role in modulating PVAT function, arterial remodeling, and vascular aging. In the present article, we summarize recent findings, review the molecular mechanisms and the potential of SIRT1 as a therapeutic target for the treatment of vascular diseases, and discuss future research directions.

Potential mechanisms underlying cardiovascular protection by polyphenols: Role of the endothelium

Epidemiological studies have indicated that regular intake of polyphenol-rich diets such as red wine and tea, are associated with a reduced risk of cardiovascular diseases. The beneficial effect of polyphenol-rich products has been attributable, at least in part, to their direct action on the endothelial function. Indeed, polyphenols from tea, grapes, cacao, berries, and plants have been shown to activate endothelial cells to increase the formation of potent vasoprotective factors including nitric oxide (NO) and to delay endothelial ageing. Moreover, intake of such polyphenol-rich products has been associated with the prevention and/or the improvement of an established endothelial dysfunction in several experimental models of cardiovascular diseases and in Humans with cardiovascular diseases. This review will discuss both experimental and clinical evidences indicating that polyphenols are able to promote endothelial and vascular health, as well as the underlying mechanisms.

Tannic acid as a plant-derived polyphenol exerts vasoprotection via enhancing KLF2 expression in endothelial cells

The transcription factor Kruppel-like factor 2 (KLF2) is a critical anti-inflammatory and anti-atherogenic molecule in vascular endothelium. Enhancing KLF2 expression and activity improves endothelial function and prevents atherosclerosis. However, the pharmacological and molecular regulators for KLF2 are scarce. Using high-throughput luciferase reporter assay to screen for KLF2 activators, we have identified tannic acid (TA), a polyphenolic compound, as a potent KLF2 activator that attenuates endothelial inflammation. Mechanistic studies suggested that TA induced KLF2 expression in part through the ERK5/MEF2 pathway. Functionally, TA markedly decreased monocyte adhesion to ECs by reducing expression of adhesion molecule VCAM1. Using lung ECs isolated from Klf2^+/+ and Klf2^+/− mice, we showed that the anti-inflammatory effect of TA is dependent on KLF2. Collectively, our results demonstrate that TA is a potent KLF2 activator and TA attenuated endothelial inflammation through upregulation of KLF2. Our findings provide a novel mechanism for the well-established beneficial cardiovascular effects of TA and suggest that KLF2 could be a novel therapeutic target for atherosclerotic vascular disease.

Fruits for Prevention and Treatment of Cardiovascular Diseases

Cardiovascular diseases (CVDs) are leading global health problems. Accumulating epidemiological studies have indicated that consuming fruits was inversely related to the risk of CVDs. Moreover, substantial experimental studies have supported the protective role of fruits against CVDs, and several fruits (grape, blueberry, pomegranate, apple, hawthorn, and avocado) have been widely studied and have shown potent cardiovascular protective action. Fruits can prevent CVDs or facilitate the restoration of morphology and functions of heart and vessels after injury. The involved mechanisms included protecting vascular endothelial function, regulating lipids metabolism, modulating blood pressure, inhibiting platelets function, alleviating ischemia/reperfusion injury, suppressing thrombosis, reducing oxidative stress, and attenuating inflammation. The present review summarizes recent discoveries about the effects of fruits on CVDs and discusses potential mechanisms of actions based on evidence from epidemiological, experimental, and clinical studies.

Sirt1 Inhibits Oxidative Stress in Vascular Endothelial Cells

The vascular endothelium is a layer of cells lining the inner surface of vessels, serving as a barrier that mediates microenvironment homeostasis. Deterioration of either the structure or function of endothelial cells (ECs) results in a variety of cardiovascular diseases. Previous studies have shown that reactive oxygen species (ROS) is a key factor that contributes to the impairment of ECs and the subsequent endothelial dysfunction. The longevity regulator Sirt1 is a NAD⁺-dependent deacetylase that has a potential antioxidative stress activity in vascular ECs. The mechanisms underlying the protective effects involve Sirt1/FOXOs, Sirt1/NF-κB, Sirt1/NOX, Sirt1/SOD, and Sirt1/eNOs pathways. In this review, we summarize the most recent reports in this field to recapitulate the potent mechanisms involving the protective role of Sirt1 in oxidative stress and to highlight the beneficial effects of Sirt1 on cardiovascular functions.

Proanthocyanidins from Vitis vinifera inhibit oxidative stress-induced vascular impairment in pulmonary arteries from diabetic rats

BACKGROUND

Vitis vinifera L. (grape seed extract) is a natural source of proanthocyanidins with antioxidant and free radical-scavenging activities.

HYPOTHESIS

Grape seed extract supplementation may prevent vascular endothelium impairment associated with diabetes mellitus in rat pulmonary artery.

STUDY DESIGN

We evaluated endothelial function of rat pulmonary artery ex-vivo at the intermediate stage (4 weeks) of streptozotocin (STZ)-induced diabetes mellitus. We also evaluated the protective effect of grape seed extract administered daily, beginning the day after diabetes induction, or 15 days after diabetes induction, until the day of sacrifice. In addition, we compared the effect of grape seed extract supplementation with that of vitamin C.

METHODS

Rats were made diabetic with streptozotocin (STZ, 65mg/kg i.v.). Thirty days later rats were sacrificed and pulmonary vessels reactivity and endothelial function compared to that of age-matched healthy animals.

RESULTS

Concentration-response curves to ACh, NE, sodium nitroprusside (NO donor), but not to histamine and iloprost (prostacyclin analog), were significantly altered 4 weeks after STZ-injection. Antioxidant supplementation (3mg/kg/day) with either vitamin C or grape seed extract, starting the day after diabetes induction, significantly improved vasodilation to ACh and SNP. Norepinephrine-induced contractions were preserved by grape seed extract, but not vitamin C supplementation. Conversely, vitamin C but not grape seed extract showed beneficial effects contrasting the loss of body weight in diabetic animals. Abnormal vascular function was not reversed when antioxidant supplementations were postponed 15 days after the induction of diabetes.

CONCLUSIONS

This study provides scientific support for the therapeutic potential of an antioxidant therapy in endothelial impairment associated with diabetes. A daily supplementation of grape seed proanthocyanidins and/or vitamin C given at the earlier stage of disease may have a complementary role in the pharmacological therapy of diabetes and pulmonary vascular dysfunction.

Grape seed procyanidin B2 protects podocytes from high glucose-induced mitochondrial dysfunction and apoptosis via the AMPK-SIRT1-PGC-1α axis in vitro

Grape seed procyanidin B2 (GSPB2) was reported to have protective effects on diabetic nephropathy (DN) as a strong antioxidant. Our previous studies demonstrated that GSPB2 was effective in ameliorating podocyte injury in rats with DN. However, little is known about the benefits of GSPB2 in protecting against podocyte apoptosis and its molecular mechanisms in vitro. In the present study, we investigated whether GSPB2 could protect podocytes from high glucose-induced apoptosis and explored the possible mechanism. Cell viability and apoptosis were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry, respectively. The intracellular reactive oxygen species (ROS) level was measured using a dichlorofluorescein diacetate (DCFH-DA) fluorescent probe. Real-time reverse transcription-PCR was used to determine the gene expression of nuclear respiratory factor 1 (NRF-1) and mitochondrial transcription factor A (TFAM), and quantitative real-time PCR was used to detect mitochondrial DNA (mtDNA) copy number. Western blots were carried out for the related protein expression in podocytes. Our results showed that GSPB2 significantly inhibited high glucose-induced podocyte apoptosis and increased the expression of nephrin and podocalyxin. GSPB2 treatment also suppressed intracellular ROS production and oxidative stress. The mRNA expressions of NRF-1, TFAM and mtDNA copy number were markedly increased, and mitochondrial swelling was effectively reduced in podocytes cultured under high glucose after GSPB2 treatment. The AMPK-SIRT1-PGC-1α axis was also activated by GSPB2 intervention. In conclusion, GSPB2 protected podocytes from high glucose-induced mitochondrial dysfunction and apoptosis via the AMPK-SIRT1-PGC-1α axis in vitro, suggesting a potential role of GSPB2 in the treatment of DN.

Anti-atherosclerotic plants which modulate the phenotype of vascular smooth muscle cells

BACKGROUND

Cardiovascular disease (CVD) remains the leading cause of global death, with atherosclerosis being a major contributor to this mortality. Several mechanisms are implicated in the pathogenesis of this disease. A key element in the development and progression of atherosclerotic lesions is the phenotype of vascular smooth muscle cells. Under pathophysiologic conditions such as injury, these cells switch from a contractile to a synthetic phenotype that often possesses high proliferative and migratory capacities.

PURPOSE

Despite major advances made in the management and treatment of atherosclerosis, mortality associated with this disease remains high. This mandates that other approaches be sought. Herbal medicine, especially for the treatment of CVD, has been gaining more attention in recent years. This is in no small part due to the evidence-based values associated with the consumption of many plants as well as the relatively cheaper prices, easier access and conventional folk medicine "inherited" over generations. Sections: In this review, we provide a brief introduction about the pathogenesis of atherosclerosis then we highlight the role of vascular smooth muscle cells in this disease, especially when a phenotypic switch of these cells arises. We then thoroughly discuss the various plants that show potentially beneficial effects as anti-atherosclerotic, with prime attention given to herbs and plants that inhibit the phenotypic switch of vascular smooth muscle cells.

CONCLUSION

Accumulating evidence provides the justification for the use of botanicals in the treatment or prevention of atherosclerosis. However, further studies, especially clinical ones, are warranted to better define several pharmacological parameters of these herbs, such as toxicity, tolerability, and efficacy.

Effects of cranberry extracts on gene expression in THP-1 cells

Cranberry contains high levels of nutrients and bioactive molecules that have health‐promoting properties. The purpose of the present studies was to determine if cranberry extracts (CEs) contain phytochemicals that exert anti‐inflammatory effects. The human monocytic cell line THP‐1 was treated with two CEs (CE and 90MX) and subsequently challenged with Lipopolysaccharides (LPS). Tumor necrosis factor α (TNFα) expression was decreased in the CE‐treated cells, indicative of an anti‐inflammatory effect. Gene expression microarrays identified several immune‐related genes that were responsive to CEs including interferon‐induced protein with tetratricopeptide repeats 1 and 3 (IFIT 1 and 3), macrophage scavenger receptor 1 (MSR1) and colony‐stimulating factor 2 (CSF2). In addition, in the CE‐treated cells, metallothionein 1F and other metal‐responsive genes were induced. Taken together, this data indicates that CEs contain bioactive components that have anti‐inflammatory effects and may protect cells from oxidative damage.

Effects of dietary Corinthian currants (Vitis vinifera L., var. Apyrena) on atherosclerosis and plasma phenolic compounds during prolonged hypercholesterolemia in New Zealand White rabbits

Corinthian currants are a rich source of phenolic compounds, which are known to exert beneficial effects on cardiovascular disease. The hypothesis tested is whether dietary supplementation with currants attenuates atherosclerosis and affects plasma phenolics during prolonged hypercholesterolemia in rabbits. Thirty New Zealand White rabbits were fed one of four diets (normal and supplemented with 10% currants, with 0.5% cholesterol, and with 0.5% cholesterol plus 10% currants) for eight weeks. Plasma lipids, glucose and hepatic enzymes were determined. Individual phenolic compounds were identified and quantified in plasma during the dietary intervention. At the end of the study, histological examinations of aorta and liver were performed. The high-cholesterol diet resulted in hypercholesterolemia and oxidative stress, increased aspartate aminotransferase (AST) activity and induced aortic and hepatic lesion formation. Corinthian currant supplementation attenuated atherosclerotic lesions, maintained AST within the normal range and reduced oxidative stress without affecting glucose concentrations. The p-OH-benzoic and p-OH-phenylacetic acids predominated at high concentrations in plasma and remained almost constant during the study in the group that received the normal rabbit chow and the groups given food with added cholesterol either alone or supplemented with currants. Currant supplementation to the normal diet resulted in the reduced absorption of phenolic compounds, as revealed by the measurement of their plasma metabolites, suggesting a regulatory mechanism at the gut level under normal conditions.

Proanthocyanidin Protects Human Embryo Hepatocytes from Fluoride-Induced Oxidative Stress by Regulating Iron Metabolism

To investigate whether grape seed proanthocyanidin extract (GSPE) antagonizes fluoride-induced oxidative injury by regulating iron metabolism, human embryo hepatic cells (L-02) were incubated with sodium fluoride (NaF, 80 mg/L) and/or GSPE (100 μmol/L) for 24 h. Results showed the glutathione peroxidase (GSH-Px) content, superoxide dismutase (SOD) activity, and total antioxidant capacity (T-AOC) level of the NaF group were significantly lower than that of the control group (P < 0.05), while malondialdehyde (MDA) content increased in the NaF group compared with the control group (P < 0.05). Moreover, the indexes mentioned above showed opposite changes in the NaF + GSPE group. In addition, iron content significantly increased in the NaF group compared to the control group(P < 0.05) and significantly decreased in the NaF + GSPE group compared to the NaF group (P < 0.05). Furthermore, hepcidin (coded by HAMP) messenger RNA (mRNA) expression significantly increased in the NaF group compared to the control group(P < 0.05) and significantly decreased in the NaF + GSPE group compared to the NaF group (P < 0.05). Ferroportin 1 (coded by FPN1) mRNA expression significantly decreased in the NaF group compared to the control group (P < 0.05) and significantly increased in the NaF + GSPE group compared to the NaF group (P < 0.05). These results indicate that GSPE provides significant cellular protection against oxidative stress induced by excessive fluoride via the iron metabolism regulation.

Adaptive cellular stress pathways as therapeutic targets of dietary phytochemicals: focus on the nervous system

During the past 5 decades, it has been widely promulgated that the chemicals in plants that are good for health act as direct scavengers of free radicals. Here we review evidence that favors a different hypothesis for the health benefits of plant consumption, namely, that some phytochemicals exert disease-preventive and therapeutic actions by engaging one or more adaptive cellular response pathways in cells. The evolutionary basis for the latter mechanism is grounded in the fact that plants produce natural antifeedant/noxious chemicals that discourage insects and other organisms from eating them. However, in the amounts typically consumed by humans, the phytochemicals activate one or more conserved adaptive cellular stress response pathways and thereby enhance the ability of cells to resist injury and disease. Examplesof such pathways include those involving the transcription factors nuclear factor erythroid 2-related factor 2, nuclear factor-κB, hypoxia-inducible factor 1α, peroxisome proliferator-activated receptor γ, and forkhead box subgroup O, as well as the production and action of trophic factors and hormones. Translational research to develop interventions that target these pathways may lead to new classes of therapeutic agents that act by stimulating adaptive stress response pathways to bolster endogenous defenses against tissue injury and disease. Because neurons are particularly sensitive to potentially noxious phytochemicals, we focus on the nervous system but also include findings from other cell types in which actions of phytochemicals on specific signal transduction pathways have been more thoroughly studied.

Regulation of vascular endothelial genes by dietary flavonoids: structure-expression relationship studies and the role of the transcription factor KLF-2

Physiological concentrations (1 μM) of 15 flavonoids were evaluated in human umbilical vein endothelial cells in the presence of hydrogen peroxide (H₂O₂) for their ability to affect endothelial nitric oxide synthase (eNOS) and endothelin-1 (ET-1) expression in order to establish the structural basis of their bioactivity. Flavonoid effects on eNOS transcription factor Krüpple like factor-2 (KLF-2) expression were also evaluated. All studied flavonoids appeared to be effective compounds for counteracting the oxidative stress-induced effects on vascular gene expression, indicating that flavonoids are an excellent source of functional endothelial regulator products. Notably, the more effective flavonoids for KLF-2 up-regulation resulted in the highest values for eNOS expression, showing that the increment of eNOS expression would take place through KLF-2 induction. Structure-activity relationship studies showed that the combinations of substructures on flavonoid skeleton that regulate eNOS expression are made up of the following elements: glycosylation and hydroxylation of C-ring, double bond C2=C3 at C-ring, methoxylation and hydroxylation of B-ring, ketone group in C4 at C-ring and glycosylation in C7 of A-ring, while flavonoid features involved in the reduction of vasoconstrictor ET-1 expression are as follows: double bond C2=C3 at C-ring glycosylation in C7 of A-ring and ketone group in C4 of C-ring.

Grape seed procyanidin B2 ameliorates mitochondrial dysfunction and inhibits apoptosis via the AMP-activated protein kinase-silent mating type information regulation 2 homologue 1-PPARγ co-activator-1α axis in rat mesangial cells under high-dose glucosamine

Grape seed procyanidin B2 (GSPB2), an antioxidative and anti-inflammatory polyphenol in grape seed, has been found to have protective effects on diabetic nephropathy. Based on its favourable biological activities, in the present study, we aimed to investigate whether GSPB2 could inhibit apoptosis in rat mesangial cells treated with glucosamine (GlcN) under high-dose conditions. The results showed that the administration of GSPB2 (10 μg/ml) significantly increased the viability of mesangial cells treated with GlcN at a dose of 15 mM. We found that GSPB2 inhibited apoptosis in mesangial cells using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphates (dUTP) nick-end labelling staining and flow cytometry technique (P< 0·05 for both). GSPB2 treatment also suppressed oxidative stress by elevating the activity of glutathione peroxidase (P< 0·05) and superoxide dismutase (P< 0·01), as well as prevented cellular damage. GSPB2 enhanced the mRNA expression of nuclear respiratory factor 1, mitochondrial transcription factor A and mitochondrial DNA copy number in mesangial cells as determined by real-time PCR (P< 0·05 for each). Finally, GSPB2 treatment activated the protein expression of PPARγ co-activator-1α (PGC-1α), silent mating type information regulation 2 homologue 1 (SIRT1) and AMP-activated protein kinase (AMPK) in mesangial cells. These findings suggest that GSPB2 markedly ameliorates mitochondrial dysfunction and inhibits apoptosis in rat mesangial cells treated with high-dose GlcN. This protective effect could be, at least in part, due to the activation of the AMPK-SIRT1-PGC-1α axis.

Does grape seed extract potentiate the inhibition of platelet reactivity in the presence of endothelial cells?

PURPOSE

Numerous studies have suggested that grape seed extract (GSE) confers vascular protection due to the direct effect of its polyphenol content on endothelial cells. The aim of the study was to determine whether GSE confers vascular protection through the direct effect of its polyphenol content on endothelial cells.

MATERIAL/METHODS

After incubation with GSE-treated human umbilical vein endothelial cells (HUVECs), blood platelet reactivity was evaluated with regard to the expression of CD62P and the activated form of GPIIbIIIa in ADP-stimulated platelets.

RESULTS

Lower concentrations of GSE were found to enhance the antiplatelet action of HUVECs: 1 μg/ml GSE reduced platelet reactivity by about 10%. While platelet reactivity was not altered by HUVECs incubated with higher concentrations of GSE, HUVEC proliferation was significantly reduced by GSE of up to 10 μg gallic acid equivalent/ml.

CONCLUSIONS

The results of the study show that low doses of GSE potentiate the inhibitory action of HUVECs on platelet reactivity, which may account, at least partially, for the protective effects of grape products against cardiovascular diseases. In contrast, high concentrations of GSE significantly impair endothelial cell proliferation in vitro.

Immunomodulating activity of Aronia melanocarpa polyphenols

The immunomodulating effects of isolated proanthocyanidin-rich fractions, procyanidins C1, B5 and B2 and anthocyanins of Aronia melanocarpa were investigated. In this work, the complement-modulating activities, the inhibitory activities on nitric oxide (NO) production in LPS-induced RAW 264.7 macrophages and effects on cell viability of these polyphenols were studied. Several of the proanthocyanidin-rich fractions, the procyanidins C1, B5 and B2 and the cyanidin aglycone possessed strong complement-fixing activities. Cyanidin 3-glucoside possessed stronger activity than the other anthocyanins. Procyanidins C1, B5 and B2 and proanthocyanidin-rich fractions having an average degree of polymerization (PD) of 7 and 34 showed inhibitory activities on NO production in LPS-stimulated RAW 264.7 mouse macrophages. All, except for the fraction containing proanthocyanidins with PD 34, showed inhibitory effects without affecting cell viability. This study suggests that polyphenolic compounds of A. melanocarpa may have beneficial effects as immunomodulators and anti-inflammatory agents.

PPARα ligand clofibrate ameliorates blood pressure and vascular reactivity in spontaneously hypertensive rats

AIM

Peroxisome proliferator activated receptors (PPARs) are nuclear transcription factors that regulate numerous genes influencing blood pressure. The aim of this study was to examine the effects of clofibrate, a PPARα ligand, on blood pressure in spontaneously hypertensive rats (SHR).

METHODS

Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR), 8-9 weeks old, were randomly allocated into groups treated with vehicle or clofibrate (250 mg·kg(-1)·d(-1), ip for 21 d). Systolic blood pressure (SBP) was measured before and after the study period using tail-cuff plethysmography. Rats were sacrificed under anesthesia and blood, urine and tissue samples were processed for subsequent analysis.

RESULTS

SHR rats showed significantly higher SBP compared with WKY rats (198±6 mmHg vs 93±7 mmHg), and a 3-fold increase in urinary protein excretion. Clofibrate treatment reduced SBP by 26%±2% and proteinuria by 43%±9% in SHR but not in WKY rats. The urinary nitrite/nitrate excretion in SHR rats was nearly 2-fold greater than that in WKY, and was further increased by 30%±4% and 48%±3%, respectively, following clofibrate treatment. In addition, PPARα protein expression and PPARα activity were significantly lower in SHR than that in WKY rats. Clofibrate treatment significantly increased PPARα protein expression and PPARα activity in SHR rats, but not in WKY rats. Moreover, the vasoconstrictor response of aortic ring was markedly increased in SHRs, which was blunted after clofibrate treatment.

CONCLUSION

PPARα contributes to regulation of blood pressure and vascular reactivity in SHR, and clofibrate-mediated reduction in blood pressure and proteinuria is probably through increased NO production.

Regulation of an inflammatory disease: Krüppel-like factors and atherosclerosis

This invited review summarizes work presented in the Russell Ross lecture delivered at the 2012 proceedings of the American Heart Association. We begin with a brief overview of the structural, cellular, and molecular biology of Krüppel-like factors. We then focus on discoveries during the past decade, implicating Krüppel-like factors as key determinants of vascular cell function in atherosclerotic vascular disease.

Mesenchymal stem cells rescue injured endothelial cells in an in vitro ischemia-reperfusion model via tunneling nanotube like structure-mediated mitochondrial transfer

Mesenchymal stem cells can be used as a novel treatment of ischemic vascular disease; however, their therapeutic effect and mechanism of action require further evaluation. Mitochondrial dysfunction has core functions in ischemia-reperfusion injury of the microvascular network. A recent discovery has shown that intercellular communication using tunneling nanotubes can transfer mitochondria between adjacent cells. This study aimed to investigate the tunneling nanotube mechanisms that might be involved in stem cell-mediated mitochondrial rescue of injured vascular endothelial cells. Using laser scanning confocal microscopy, mitochondrial transfer via a tunneling nanotube-like structure was detected between mesenchymal stem cells and human umbilical vein endothelial cells. Oxygen glucose deprivation and reoxygenation were performed on human umbilical vein endothelial cells, which induced mitochondrial transfer through tunneling nanotube-like structures to become frequent and almost unidirectional from mesenchymal stem cells to injured endothelial cells, thereby resulting in the rescue of aerobic respiration and protection of endothelial cells from apoptosis. We found that the formation of tunneling nanotube-like structures might represent a defense and rescue mechanism through phosphatidylserines exposed on the surface of apoptotic endothelial cells and stem cell recognition. Our data provided evidence that stem cells can rescue damaged vascular endothelial cells through a mechanism that has not yet been identified.