Docosahexaenoic acid improves vascular function via up-regulation of SIRT1 expression in endothelial cells

Omega-3 polyunsaturated fatty acids and pulmonary arterial hypertension: Insights and perspectives

Pulmonary arterial hypertension (PAH) is a rare and progressive disorder that affects the pulmonary vasculature. Although recent developments in pharmacotherapy have extended the life expectancy of PAH patients, their 5-year survival remains unacceptably low, underscoring the need for multitarget and more comprehensive approaches to managing the disease. This should incorporate not only medical, but also lifestyle interventions, including dietary changes and the use of nutraceutical support. Among these strategies, n-3 polyunsaturated fatty acids (n-3 PUFAs) are emerging as promising agents able to counteract the inflammatory component of PAH. In this narrative review, we aim at analysing the preclinical evidence for the impact of n-3 PUFAs on the pathogenesis and the course of PAH. Although evidence for the role of n-3 PUFAs deficiencies in the development and progression of PAH in humans is limited, preclinical studies suggest that these dietary components may influence several aspects of the pathobiology of PAH. Further clinical research should test the efficacy of n-3 PUFAs on top of approved clinical management. These studies will provide evidence on whether n-3 PUFAs can genuinely serve as a valuable tool to enhance the efficacy of pharmacotherapy in the treatment of PAH.

Impact of dairy fat manipulation on endothelial function and lipid regulation in human aortic endothelial cells exposed to human plasma samples: an in vitro investigation from the RESET study

PURPOSE

Longer-term intake of fatty acid (FA)-modified dairy products (SFA-reduced, MUFA-enriched) was reported to attenuate postprandial endothelial function in humans, relative to conventional (control) dairy. Thus, we performed an in vitro study in human aortic endothelial cells (HAEC) to investigate mechanisms underlying the effects observed in vivo.

METHODS

This sub-study was conducted within the framework of the RESET study, a 12-week randomised controlled crossover trial with FA-modified and control dairy diets. HAEC were incubated for 24 h with post-intervention plasma samples from eleven adults (age: 57.5 ± 6.0 years; BMI: 25.7 ± 2.7 kg/m2) at moderate cardiovascular disease risk following representative sequential mixed meals. Markers of endothelial function and lipid regulation were assessed.

RESULTS

Relative to control, HAEC incubation with plasma following the FA-modified treatment increased postprandial NOx production (P-interaction = 0.019), yet up-regulated relative E-selectin mRNA gene expression (P-interaction = 0.011). There was no impact on other genes measured.

CONCLUSION

Incubation of HAEC with human plasma collected after longer-term dairy fat manipulation had a beneficial impact on postprandial NOx production. Further ex vivo research is needed to understand the impact of partial replacement of SFA with unsaturated fatty acids in dairy foods on pathways involved in endothelial function.

Occludin: a gatekeeper of brain Infection by HIV-1

Compromised structure and function of the blood-brain barrier (BBB) is one of the pathological hallmarks of brain infection by HIV-1. BBB damage during HIV-1 infection has been associated with modified expression of tight junction (TJ) proteins, including occludin. Recent evidence indicated occludin as a redox-sensitive, multifunctional protein that can act as both an NADH oxidase and influence cellular metabolism through AMPK kinase. One of the newly identified functions of occludin is its involvement in regulating HIV-1 infection. Studies suggest that occludin expression levels and the rate of HIV-1 infection share a reverse, bidirectional relationship; however, the mechanisms of this relationship are unclear. In this review, we describe the pathways involved in the regulation of HIV-1 infection by occludin. We propose that occludin may serve as a potential therapeutic target to control HIV-1 infection and to improve the lives of people living with HIV-1.

Deficiency of endothelial sirtuin1 in mice stimulates skeletal muscle insulin sensitivity by modifying the secretome

Downregulation of endothelial Sirtuin1 (Sirt1) in insulin resistant states contributes to vascular dysfunction. Furthermore, Sirt1 deficiency in skeletal myocytes promotes insulin resistance. Here, we show that deletion of endothelial Sirt1, while impairing endothelial function, paradoxically improves skeletal muscle insulin sensitivity. Compared to wild-type mice, male mice lacking endothelial Sirt1 (E-Sirt1-KO) preferentially utilize glucose over fat, and have higher insulin sensitivity, glucose uptake, and Akt signaling in fast-twitch skeletal muscle. Enhanced insulin sensitivity of E-Sirt1-KO mice is transferrable to wild-type mice via the systemic circulation. Endothelial Sirt1 deficiency, by inhibiting autophagy and activating nuclear factor-kappa B signaling, augments expression and secretion of thymosin beta-4 (Tβ4) that promotes insulin signaling in skeletal myotubes. Thus, unlike in skeletal myocytes, Sirt1 deficiency in the endothelium promotes glucose homeostasis by stimulating skeletal muscle insulin sensitivity through a blood-borne mechanism, and augmented secretion of Tβ4 by Sirt1-deficient endothelial cells boosts insulin signaling in skeletal muscle cells.

Signaling pathways in cancer metabolism: mechanisms and therapeutic targets

A wide spectrum of metabolites (mainly, the three major nutrients and their derivatives) can be sensed by specific sensors, then trigger a series of signal transduction pathways and affect the expression levels of genes in epigenetics, which is called metabolite sensing. Life body regulates metabolism, immunity, and inflammation by metabolite sensing, coordinating the pathophysiology of the host to achieve balance with the external environment. Metabolic reprogramming in cancers cause different phenotypic characteristics of cancer cell from normal cell, including cell proliferation, migration, invasion, angiogenesis, etc. Metabolic disorders in cancer cells further create a microenvironment including many kinds of oncometabolites that are conducive to the growth of cancer, thus forming a vicious circle. At the same time, exogenous metabolites can also affect the biological behavior of tumors. Here, we discuss the metabolite sensing mechanisms of the three major nutrients and their derivatives, as well as their abnormalities in the development of various cancers, and discuss the potential therapeutic targets based on metabolite-sensing signaling pathways to prevent the progression of cancer.

Growth State-Dependent Activation of eNOS in Response to DHA: Involvement of p38 MAPK

Our laboratory previously reported that docosahexaenoic acid (DHA) differentially activates p38 mitogen-activated protein kinase (MAPK) in growing and quiescent human endothelial cells, which represent the dysfunctional and healthy states in vivo, respectively. Since endothelial nitric oxide synthase (eNOS) activity differs between healthy and dysfunctional endothelial cells, and p38 MAPK reportedly regulates both the activity and expression of eNOS, we hypothesized that the beneficial actions of DHA on endothelial cells are due to eNOS activation by p38 MAPK. The contribution of mitogen- and stress-activated protein kinase (MSK), a p38 MAPK substrate, was also investigated. Growing and quiescent EA.hy926 cells, prepared on Matrigel^®-coated plates, were incubated with inhibitors of p38MAPK or MSK before adding DHA. eNOS phosphorylation and levels were quantified by Western blotting. Treatment with 20 µM DHA activated eNOS in both growth states whereas 125 µM DHA suppressed eNOS activation in growing cells. Quiescent cells had higher basal levels of eNOS than growing cells, while 125 µM DHA decreased eNOS levels in both growth states. p38 MAPK inhibition enhanced eNOS activation in quiescent cells but suppressed it in growing cells. Interestingly, 125 µM DHA counteracted these effects of p38 MAPK inhibition in both growth states. MSK was required for eNOS activation in both growth states, but it only mediated eNOS activation by DHA in quiescent cells. MSK thus affects eNOS via a pathway independent of p38MAPK. Quiescent cells were also more resistant to the apoptosis-inducing effect of 125 µM DHA compared to growing cells. The growth state-dependent regulation of p38MAPK and eNOS by DHA provides novel insight into the molecular mechanisms by which DHA influences endothelial cell function.

Fatty acids act on vascular endothelial cells and influence the development of cardiovascular disease

Endothelial cells (ECs) maintain the health of blood vessels and prevent the development of cardiovascular disease (CVD). Free saturated fatty acids (FAs) induce EC damage and increase the risk of CVD by promoting arteriosclerosis. Conversely, polyunsaturated FAs (PUFAs), such as docosahexaenoic acid, are thought to suppress EC damage induced during the early stages of CVD. This review describes the effects of multiple dietary FAs on EC disorders involved in the development of CVD. The roles of FAs in atherosclerosis and CVD were analyzed by evaluating articles published in PubMed, Science Direct, and Web of Science. Saturated FAs were found to induce EC damage by reducing the production and action of EC-derived nitric oxide. Oxidative stress, inflammation, and the renin-angiotensin system were found to be involved in EC disorder. Furthermore, n-3 PUFAs were found to reduce EC dysfunction and prevent the development of EC disorder. These results indicate that FAs may affect EC failure induced during the early stages of CVD and reduce the risk of developing the disease.

Effects of Combining Docosahexaenoic Acid and Eicosapentaenoic Acid with Sesame Lignan on Vascular Endothelial Function

Vascular endothelial cells produce vasoactive substances, such as nitric oxide (NO), to regulate vascular relaxation and contraction. Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) enhance NO production in endothelial cells, and sesamin, a sesame lignan contained in sesame seeds, also promotes NO production. This study examined DHA, EPA, and sesamin's combined effects since it was expected that combining them would further enhance NO production in endothelial cells. Using a human umbilical vein endothelial cell (HUVEC), the NO amount secreted in the culture supernatant was analyzed. Sesamin metabolite (SC1) was used in the experiments because it is a major metabolite in human blood after sesamin absorption. When cells were treated with DHA or EPA alone, they increased NO production in a concentration-dependent manner, whereas no change in NO production was observed for SC1. NO production increased when DHA and EPA were treated in combination with SC1, although the low DHA and EPA concentrations showed no difference in NO production. In the concentrations in which the combined effect was observed, SC1 activated eNOS via calcium signaling, whereas DHA and EPA activated eNOS via alterations in the membrane lipid environment. The combined effect of the two pathways was considered to have enhanced the eNOS activity. These results suggested that combining DHA, EPA, and sesamin might improve vascular endothelial function.

An Effective Sodium-Dependent Glucose Transporter 2 Inhibition, Canagliflozin, Prevents Development of Hypertensive Heart Failure in Dahl Salt-Sensitive Rats

Background: The aim of the study was to investigate the protective effect of canagliflozin (CANA) on myocardial metabolism and heart under stress overload and to further explore its possible molecular mechanism.

Methods: High-salt diet was used to induce heart failure with preserved ejection fraction (HFpEF), and then, the physical and physiological indicators were measured. The cardiac function was evaluated by echocardiography and related indicators. Masson trichrome staining, wheat germ agglutinin, and immunohistochemical staining were conducted for histology analysis. Meanwhile, oxidative stress and cardiac ATP production were also determined. PCR and Western blotting were used for quantitative detection of related genes and proteins. Comprehensive metabolomics and proteomics were employed for metabolic analysis and protein expression analysis.

Results: In this study, CANA showed diuretic, hypotensive, weight loss, and increased intake of food and water. Dahl salt-sensitive (DSS) rats fed with a diet containing 8% NaCl AIN-76A developed left ventricular remodeling and diastolic dysfunction caused by hypertension. After CANA treatment, cardiac hypertrophy and fibrosis were reduced, and the left ventricular diastolic function was improved. Metabolomics and proteomics data confirmed that CANA reduced myocardial glucose metabolism and increased fatty acid metabolism and ketogenesis in DSS rats, normalizing myocardial metabolism and reducing the myocardial oxidative stress. Mechanistically, CANA upregulated p-adenosine 5′-monophosphate-activated protein kinase (p-AMPK) and sirtuin 1 (SIRT1) and significantly induced the expression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1a).

Conclusion: CANA can improve myocardial hypertrophy, fibrosis, and left ventricular diastolic dysfunction induced by hypertension in DSS rats, possibly through the activation of the AMPK/SIRT1/PGC-1a pathway to regulate energy metabolism and oxidative stress.

Impact of Dietary Modifications on Plasma Sirtuins 1, 3 and 5 in Older Overweight Individuals Undergoing 12-Weeks of Circuit Training

Sirtuins are nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases that regulate numerous pathways such as mitochondrial energy metabolism in the human body. Lower levels of these enzymes were linked to diseases such as diabetes mellitus and were also described as a result of aging. Sirtuins were previously shown to be under the control of exercise and diet, which are modifiable lifestyle factors. In this study, we analyzed SIRT1, SIRT3 and SIRT5 in blood from a subset of healthy elderly participants who took part in a 12-week randomized, controlled trial during which they performed, twice-weekly, resistance and aerobic training only (EX), the exercise routine combined with dietary counseling in accordance with the guidelines of the German Nutrition Society (EXDC), the exercise routine combined with intake of 2 g/day oil from Calanus finmarchicus (EXCO), or received no treatment and served as the control group (CON). In all study groups performing exercise, a significant increase in activities of SIRT1 (EX: +0.15 U/mg (+0.56/−[−0.16]), EXDC: +0.25 U/mg (+0.52/−0.06), EXCO: +0.40 U/mg (+0.88/−[−0.12])) and SIRT3 (EX: +0.80 U/mg (+3.18/−0.05), EXDC: 0.95 U/mg (+3.88/−0.55), EXCO: 1.60 U/mg (+2.85/−0.70)) was detected. Group comparisons revealed that differences in SIRT1 activity in EXCO and EXDC differed significantly from CON (CON vs. EXCO, p = 0.003; CON vs. EXDC, p = 0.010). For SIRT3, increases in all three intervention groups were significantly different from CON (CON vs. EX, p = 0.007; CON vs. EXDC, p < 0.001, CON vs. EXCO, p = 0.004). In contrast, differences in SIRT5-activities were less pronounced. Altogether, the analyses showed that the activity of SIRT1 and SIRT3 increased in response to the exercise intervention and that this increase may potentially be enhanced by additional dietary modifications.

Modulation of endothelium function by fatty acids

The endothelium acts as the barrier that prevents circulating lipids such as lipoproteins and fatty acids into the arterial wall; it also regulates normal functioning in the circulatory system by balancing vasodilation and vasoconstriction, modulating the several responses and signals. Plasma lipids can interact with endothelium via different mechanisms and produce different phenotypes. Increased plasma-free fatty acids (FFAs) levels are associated with the pathogenesis of atherosclerosis and cardiovascular diseases (CVD). Because of the multi-dimensional roles of plasma FFAs in mediating endothelial dysfunction, increased FFA level is now considered an essential link in the onset of endothelial dysfunction in CVD. FFA-mediated endothelial dysfunction involves several mechanisms, including dysregulated production of nitric oxide and cytokines, metaflammation, oxidative stress, inflammation, activation of the renin-angiotensin system, and apoptosis. Therefore, modulation of FFA-mediated pathways involved in endothelial dysfunction may prevent the complications associated with CVD risk. This review presents details as to how endothelium is affected by FFAs involving several metabolic pathways.

Dietary Betaine Mitigates Hepatic Steatosis and Inflammation Induced by a High-Fat-Diet by Modulating the Sirt1/Srebp-1/Pparɑ Pathway in Juvenile Black Seabream (Acanthopagrus schlegelii)

The present study aimed to elucidate the mechanism of dietary betaine, as a lipid-lowering substance, on the regulation of lipid metabolism and inflammation in juvenile black seabream (Acanthopagrus schlegelii) fed a high fat diet. An 8-week feeding trial was conducted in black seabream with an initial weight of 8.39 ± 0.01g fed four isonitrogenous diets including Control, medium-fat diet (11%); HFD, high-fat diet (17%); and HFD supplemented with two levels (10 and 20 g/kg) of betaine, HFD+B1 and HFD+B2, respectively. SGR and FE in fish fed HFD+B2 were significantly higher than in fish fed HFD. Liver histology revealed that vacuolar fat droplets were smaller and fewer in bream fed HFD supplemented with betaine compared to fish fed HFD. Betaine promoted the mRNA and protein expression levels of silent information regulator 1 (Sirt1), up-regulated mRNA expression and protein content of lipid peroxisome proliferator-activated receptor alpha (pparα), and down-regulated mRNA expression and protein content of sterol regulatory element-binding protein-1(srebp-1). Furthermore, the mRNA expression levels of anti-inflammatory cytokines in liver and intestine were up-regulated, while nuclear factor kB (nf-kb) and pro-inflammatory cytokines were down-regulated by dietary betaine supplementation. Likewise, in fish that received lipopolysaccharide (LPS) to stimulate inflammatory responses, the expression levels of mRNAs of anti-inflammatory cytokines in liver, intestine and kidney were up-regulated in fish fed HFD supplemented with betaine compared with fish fed HFD, while nf-kb and pro-inflammatory cytokines were down-regulated. This is the first report to suggest that dietary betaine could be an effective feed additive to alleviate hepatic steatosis and attenuate inflammatory responses in black seabream fed a high fat diet by modulating the Sirt1/Srebp-1/Pparɑ pathway.

Dietary fatty acids as nutritional modulators of sirtuins: a systematic review

CONTEXT

The sirtuins (SIRT1 to SIRT7) constitute a family of highly conserved nicotinamide adenine dinucleotide-dependent proteins. When activated, sirtuins control essential cellular processes to maintain metabolic homeostasis, while lack of expression of sirtuins has been related to chronic disease.

OBJECTIVE

The aim of this systematic review is to analyze the role of fat consumption as a modulator of human sirtuins.

DATA SOURCES

This review was conducted according to PRISMA guidelines. Studies were identified by searches of the electronic databases PubMed/MEDLINE, Scopus, and Web of Science.

STUDY SELECTION

Randomized clinical trials assessing the effect of fatty acid consumption on sirtuin mRNA expression, sirtuin protein expression, or sirtuin protein activity were eligible for inclusion.

DATA EXTRACTION

Two authors screened and determined the quality of the studies; disagreements were resolved by the third author. All authors compared the compiled data.

RESULTS

Seven clinical studies with 3 different types of interventions involving healthy and nonhealthy participants were selected. Only SIRT1 and SIRT3 were evaluated. Overall, the evidence from clinical studies to date is insufficient to understand how lipid consumption modulates sirtuins in humans. The best-characterized mechanism highlights oleic acid as a natural activator of SIRT1.

CONCLUSION

These results draw attention to a new field of interest in nutrition science. The possible activation of sirtuins by dietary fat manipulation may represent an important nutritional strategy for management of chronic and metabolic disease.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42018114456.

Omega-3 Polyunsaturated Fatty Acids: Versatile Roles in Blood Pressure Regulation

Significance: Hypertension is characterized as the imbalance of vasoconstriction and vasodilatation. Hypertension is influenced by genetic variation and environmental risk factors, such as unhealthy diet. Clinical trial results suggest that increasing intake of foods rich in n-3 polyunsaturated fatty acids (PUFAs) is beneficial for hypertension. Recent Advances: We summarized recent clinical trials regarding supplementation with n-3 PUFAs to reduce blood pressure (BP) in untreated hypertensive and normotensive subjects and systematically discussed the antihypertension mechanisms of n-3 PUFAs/n-3 oxylipins, including reducing oxidative stress, altering functions of membrane-related proteins, and competing with n-6 PUFAs/n-6 oxylipins in regulating vasodilator release. Critical Issues: Previous studies considered n-3 PUFAs as single molecules with beneficial roles in hypertension. Recently, researchers have paid more attention to the metabolism of n-3 PUFAs and explored molecular mechanisms of n-3 PUFAs and oxylipins derived from n-3 PUFAs in hypertension interventions. Future Directions: Based on the metabolism of n-3 PUFAs/n-3 oxylipins and mechanisms in BP control, we suggested that supplementation of n-3 PUFAs combined with agents targeting PUFA metabolism or the related signal pathways may amplify their effects to treat hypertension and other cardiovascular diseases. Antioxid. Redox Signal. 34, 800-810.

Potential roles of natural products in the targeting of proteinopathic neurodegenerative diseases

Defective proteostasis is associated with the gradual accumulations of misfolded proteins and is a hallmark of many age-associated neurodegenerative diseases. In the aged brain, maintenance of the proteostasis network presents a substantial challenge, and its loss contributes to the onset and progression of neurological diseases associated with cognitive decline due to the generation of toxic protein aggregates, a process termed 'proteinopathy'. Emerging evidence suggests that reversing proteinopathies by boosting proteostasis might provide an effective means of preventing neurodegeneration. From this perspective, phytochemicals may play significant roles as potent modulators of the proteostasis network, as previous reports have suggested they can interact with various network components to modify pathologies and confer neuroprotection. This review focuses on some potent phytochemicals that directly or indirectly modulate the proteostasis network and on their possible molecular targets. In addition, we propose strategies for the natural product-based modulation of proteostasis machinery that target proteinopathies.

Impact of omega-3 fatty acids on expression of angiogenic cytokines and angiogenesis by adipose-derived stem cells

BACKGROUND AND AIMS

Human adipose-tissue derived stem cells (ADSC) are interesting novel targets in tissue engineering and regenerative medicine with pronounced angiogenic capacities. Furthermore, omega-3 fatty acids have been described to mediate cardioprotective effects, but their role in angiogenesis and vascular regeneration is not well-understood. Here, we analyzed the impact of different omega-3 fatty acids on angiogenesis by ADSCs.

METHODS

Stem cells were cultured as monolayers or in 3D models, in spheroids embedded in collagen matrix or in co-cultures with human umbilical vein endothelial cells (HUVECs) in the Matrigel™ assay. The angiogenic properties of ADSCs were assessed by their sprouting and paracrine activities, gene expression by RT-PCR, Western blot, and enzyme immunoassay.

RESULTS

Stimulation of undifferentiated ADSCs with docosahexaenoic acid (DHA) strongly upregulated angiopoietin-1 mRNA levels up to 4.6 ± 0.3 fold. Furthermore, Il-6 and Il-8 mRNAs were increased 4.2 ± 0.5 fold and 7.1 ± 1.1 fold, respectively. On the other hand, addition of DHA significantly decreased the cumulative sprout length by 2.7 ± 0.8 fold and reduced the total number of sprouts by 2.3 ± 0.9 fold in the in vitro angiogenesis assay. Moreover, excretion of IL-8 into the medium rapidly increased up to 1.7 ± 0.3 fold in response to treatment of ADSCs with DHA. Finally, protein kinase C inhibitor RO-31-8220 abrogated DHA-mediated up-regulation of angiopoietin-1 without significantly affecting ADSCs cell viability.

CONCLUSION

In conclusion, ADSCs might regulate the formation and function of microvascular networks.

Omega-3 polyunsaturated fatty acids alleviate hepatic steatosis-induced inflammation through Sirt1-mediated nuclear translocation of NF-κB p65 subunit in hepatocytes of large yellow croaker (Larmichthys crocea)

Hepatic steatosis induced inflammation is becoming increasingly prevalent in farmed fish. This study was conducted to investigate the protective effects of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) against hepatic steatosis-induced inflammation and its potential molecular mechanisms in hepatocyte of large yellow croaker (Larmichthys crocea). We found that the hepatic steatosis-induced inflammation was relieved by ω-3 PUFAs, meanwhile, the Sirt1 activity and transcript expression was increased by ω-3 PUFAs. The increased Sirt1 activity can decrease the hepatic steatosis-induced inflammation. The protective effects of ω-3 PUFAs against hepatic steatosis-induced inflammation was reversed by the treatment with Sirt1 inhibitor EX-527. The nuclear translocation of nuclear transcription factor kappa-B (NF-κB) p65 was significantly decreased after ω-3 PUFAs treatments compared to the palmitic acid stimulation group. The ω-3 PUFAs induced cytoplasm translocation of NF-κB p65 was reversed by EX-527. Together, ω-3 PUFAs alleviate hepatic steatosis-induced inflammation through Sirt1-mediated nuclear translocation of NF-κB p65 subunit in hepatocytes of large yellow croaker. The present study provides important insight into the mechanisms of the protective effects of ω-3 PUFAs, providing theory bases for alleviating the hepatic steatosis induced inflammation of farmed fish, thereby offering great benefits to the aquaculture industry and fish consumers.

Regulation of Sirtuin-Mediated Protein Deacetylation by Cardioprotective Phytochemicals

Modulation of posttranslational modifications (PTMs), such as protein acetylation, is considered a novel therapeutic strategy to combat the development and progression of cardiovascular diseases. Protein hyperacetylation is associated with the development of numerous cardiovascular diseases, including atherosclerosis, hypertension, cardiac hypertrophy, and heart failure. In addition, decreased expression and activity of the deacetylases Sirt1, Sirt3, and Sirt6 have been linked to the development and progression of cardiac dysfunction. Several phytochemicals exert cardioprotective effects by regulating protein acetylation levels. These effects are mainly exerted via activation of Sirt1 and Sirt3 and inhibition of acetyltransferases. Numerous studies support a cardioprotective role for sirtuin activators (e.g., resveratrol), as well as other emerging modulators of protein acetylation, including curcumin, honokiol, oroxilyn A, quercetin, epigallocatechin-3-gallate, bakuchiol, tyrosol, and berberine. Studies also point to a cardioprotective role for various nonaromatic molecules, such as docosahexaenoic acid, alpha-lipoic acid, sulforaphane, and caffeic acid ethanolamide. Here, we review the vast evidence from the bench to the clinical setting for the potential cardioprotective roles of various phytochemicals in the modulation of sirtuin-mediated deacetylation.

Omega 3 Polyunsaturated Fatty Acids Improve Endothelial Dysfunction in Chronic Renal Failure: Role of eNOS Activation and of Oxidative Stress

Background: Endothelial dysfunction is a key vascular alteration in chronic kidney disease (CKD). Omega 3 (n-3) polyunsaturated fatty acids (PUFA) reduce vascular oxidative stress and inflammation. We investigated whether n-3 PUFA could reverse endothelial dysfunction in CKD by improving endothelial nitric oxide synthase (eNOS) function and oxidative stress. Methods: 5/6 nephrectomized male Wistar rats (CKD; n = 10) and sham operated animals (SHAM; n = 10) were treated for 6 weeks with standard diet. An additional group of CKD rats were fed an n-3 PUFA enriched diet (CKD + PUFA; n = 10). We then measured endothelium-dependent (EDD) and -independent vasodilation, markers of endothelial function and of oxidative stress in thoracic aortas. Results: Compared to SHAM, in CKD aortas EDD and eNOS expression were reduced (p < 0.05) and 3-nitrotyrosine levels were increased, while expression of NADPH oxidase subunits NOX4 and p22^phox was similar. In-vitro incubation with Tiron failed to reverse endothelial dysfunction in CKD. In CKD + PUFA, EDD improved (p < 0.05) compared with CKD rats, while blockade of eNOS by L-NAME worsened EDD. These effects were accompanied by increased (p < 0.05) eNOS and reduced (p < 0.05) expression of NOX4 and 3-nitrotyrosine levels. Conclusion: Collectively, these findings indicate that n-3 PUFA improve endothelial dysfunction by restoring NO bioavailability in CKD.

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.

Assessment of DHA on reducing early preterm birth: the ADORE randomized controlled trial protocol

BACKGROUND

Preterm birth contributes to 0.5 million deliveries in the United States (one of eight pregnancies) and poses a huge burden on public health with costs in the billions. Of particular concern is that the rate of earliest preterm birth (<34 weeks) (ePTB), which has decreased little since 1990 and has the greatest impact on the overall infant mortality, resulting in the greatest cost to society. Docosahexaenoic acid (DHA) supplementation provides a potential high yield, low risk strategy to reduce early preterm delivery in the US by up to 75%. We propose a Phase III Clinical Trial (randomized to low or high dose DHA, double-blinded) to examine the efficacy and safety of high dose DHA supplementation to reduce ePTB. We also plan for a secondary pregnancy efficacy analysis to determine if there is a subset of pregnancies most likely to benefit from DHA supplementation.

METHODS

Between 900 and 1200 pregnant women who are ≥ 18 years old and between 12 and 20 weeks gestation will be recruited from three trial experienced academic medical institutions. Participants will be randomly assigned to two daily capsules of algal oil (totaling 800 mg DHA) or soybean and corn oil (0 mg DHA). Both groups will receive a commercially available prenatal supplement containing 200 mg DHA. Therefore, the experimental group will receive 1000 mg DHA/d and the control group 200 mg DHA/d. We will then employ a novel Bayesian response adaptive randomization design that assigns more subjects to the "winning" group and potentially allows for substantially smaller sample size while providing a stronger conclusion regarding the most effective group. The study has an overall Type I error rate of 5% and a power of 90%. Participants are followed throughout pregnancy and delivery for safety and delivery outcomes.

DISCUSSION

We hypothesize that DHA will decrease the frequency of ePTB <34 weeks. Reducing ePTB is clinically important as these earliest preterm deliveries carry the highest risk of neonatal morbidity, as well as contribute significant stress for families and post a large societal burden.

TRIAL REGISTRATION

This trial was registered with ClinicalTrials.gov (identifier: NCT02626299 ) on December 8, 2015. Additional summary details may be found in Table 1.

P66Shc-Induced MicroRNA-34a Causes Diabetic Endothelial Dysfunction by Downregulating Sirtuin1

OBJECTIVE

Diabetes mellitus causes vascular endothelial dysfunction and alters vascular microRNA expression. We investigated whether endothelial microRNA-34a (miR-34a) leads to diabetic vascular dysfunction by targeting endothelial sirtuin1 (Sirt1) and asked whether the oxidative stress protein p66Shc governs miR-34a expression in the diabetic endothelium.

APPROACH AND RESULTS

MiR-34a is upregulated, and Sirt1 downregulated, in aortic endothelium of db/db and streptozotocin-induced diabetic mice. Systemic administration of miR-34a inhibitor, or endothelium-specific knockout of miR-34a, prevents downregulation of aortic Sirt1 and rescues impaired endothelium-dependent aortic vasorelaxation induced by diabetes mellitus. Moreover, overexpression of Sirt1 mitigates impaired endothelium-dependent vasorelaxation caused by miR-34a mimic ex vivo. Systemic infusion of miR-34a inhibitor or genetic ablation of endothelial miR-34a prevents downregulation of endothelial Sirt1 by high glucose. MiR-34a is upregulated, Sirt1 is downregulated, and oxidative stress (hydrogen peroxide) is induced in endothelial cells incubated with high glucose or the free fatty acid palmitate in vitro. Increase of hydrogen peroxide and induction of endothelial miR-34a by high glucose or palmitate in vitro is suppressed by knockdown of p66shc. In addition, overexpression of wild-type but not redox-deficient p66Shc upregulates miR-34a in endothelial cells. P66Shc-stimulated upregulation of endothelial miR-34a is suppressed by cell-permeable antioxidants. Finally, mice with global knockdown of p66Shc are protected from diabetes mellitus-induced upregulation of miR-34a and downregulation of Sirt1 in the endothelium.

CONCLUSIONS

These data show that hyperglycemia and elevated free fatty acids in the diabetic milieu recruit p66Shc to upregulate endothelial miR-34a via an oxidant-sensitive mechanism, which leads to endothelial dysfunction by targeting Sirt1.

SIRT Is Required for EDP-Mediated Protective Responses toward Hypoxia-Reoxygenation Injury in Cardiac Cells

Hypoxia–reoxygenation (H/R) injury is known to cause extensive injury to cardiac myocardium promoting development of cardiac dysfunction. Despite the vast number of studies dedicated to studying H/R injury, the molecular mechanisms behind it are multiple, complex, and remain very poorly understood, which makes development of novel pharmacological agents challenging. Docosahexaenoic acid (DHA, 22:6n3) is an n - 3 polyunsaturated fatty acid obtained from dietary sources, which produces numerous effects including regulation of cell survival and death mechanisms. The beneficial effects of DHA toward the cardiovascular system are well documented but the relative role of DHA or one of its more potent metabolites is unresolved. Emerging evidence indicates that cytochrome P450 (CYP) epoxygenase metabolites of DHA, epoxydocosapentaenoic acids (EDPs), have more potent biological activity than DHA in cardiac cells. In this study we examined whether EDPs protect HL-1 cardiac cells from H/R injury. Our observations demonstrate that treatment with 19,20-EDP protected HL-1 cardiac cells from H/R damage through a mechanism(s) protecting and enhancing mitochondrial quality. EDP treatment increased the relative rates of mitobiogenesis and mitochondrial respiration in control and H/R exposed cardiac cells. The observed EDP protective response toward H/R injury involved SIRT1-dependent pathways.

Epigenetic regulation of gene expression and M2 macrophage polarization as new potential omega-3 polyunsaturated fatty acid targets in colon inflammation and cancer

INTRODUCTION

It has become increasingly clear that dietary habits may affect the risk/progression of chronic diseases with a pathogenic inflammatory component, such as colorectal cancer. Considerable attention has been directed toward the ability of nutritional agents to target key molecular pathways involved in these inflammatory-related diseases.

AREAS COVERED

ω-3 Polyunsaturated fatty acids (PUFA) and their oxidative metabolites have attracted considerable interest as possible anti-inflammatory and anti-cancer agents, especially in areas such as the large bowel, where the influence of orally introduced substances is high and tumors show deranged PUFA patterns. On this basis, we have analyzed pre-clinical findings that have recently revealed new insight into the molecular pathways targeted by ω-3 PUFA.

EXPERT OPINION

The findings analyzed herein demonstrate that ω-3 PUFA may exert beneficial effects by targeting the epigenetic regulation of gene expression and altering M2 macrophage polarization during the inflammatory response. These mechanisms need to be better explored in the large bowel, and further studies could better clarify their role and the potential of dietary interventions with ω-3 PUFA in the large bowel. The epigenomic mechanism is discussed in view of the potential of ω-3 PUFA to enhance the efficacy of other agents used in the therapy of colorectal cancer.

CYP-epoxygenase metabolites of docosahexaenoic acid protect HL-1 cardiac cells against LPS-induced cytotoxicity Through SIRT1

Bacterial LPS is an environmental toxin capable of promoting various cardiac complications. Current evidence suggests that LPS-induced myocardial dysfunction emerges as a consequence of compromised quality of cardiac mitochondria. Docosahexaenoic acid (DHA, 22:6n3) is an n-3 polyunsaturated fatty acid (PUFA), which produces a broad spectrum of intrinsic physiological effects including regulation of cell survival and death mechanisms. Although, numerous studies revealed fundamentally beneficial effects of DHA on cardiovascular system, it remains unknown whether these effects were produced by DHA or one of its possibly more potent metabolites. Emerging evidence indicates that cytochrome P450 (CYP) epoxygenase metabolites of DHA, epoxydocosapentaenoic acids (EDPs), produce more potent biological activity compared to its precursor DHA. In this study, we investigated whether DHA and its metabolite 19,20-EDP could protect HL-1 cardiac cells against LPS-induced cytotoxicity. We provide evidence that exogenously added or DHA-derived EDPs promote mitochondrial biogenesis and function in HL-1 cardiac cells. Our results illustrate the CYP epoxygenase metabolite of DHA, 19,20-EDP, confers extensive protection to HL-1 cardiac cells against LPS-induced cytotoxicity via activation of SIRT1.

SIRT1 and Kidney Function

BACKGROUND

SIRT1 is a nicotinamide adenine dinucleotide-dependent deacetylase belonging to the class III histone deacetylases. Abundantly expressed in the kidney, especially in the renal medulla, SIRT1 is closely involved in renal physiology and pathology.

SUMMARY

SIRT1 targets both histone and nonhistone proteins, participates in many important signaling pathways and mediates the regulation of longevity, metabolic homeostasis, acute stress response and DNA integrity. With regard to the kidney, SIRT1 attenuates diabetic albuminuria, reduces blood pressure and related cardiovascular diseases, resists acute kidney injury, delays kidney fibrogenesis, promotes cyst formation and benefits renal ageing.

KEY MESSAGES

This review summarizes the biology of SIRT1 and focuses on the latest studies concerning SIRT1 as a potential therapeutic target for kidney diseases.

Role of dietary fish oil on nitric oxide synthase activity and oxidative status in mice red blood cells

The consumption of n-3 polyunsaturated fatty acids derived from fish oil is associated with cardiovascular benefits, which may result from the participation of nitric oxide.