Taurine and atherosclerosis

The role of taurine through endoplasmic reticulum in physiology and pathology

Taurine is a sulfur-containing amino acid found in many cell organelles that plays a wide range of biological roles, including bile salt production, osmoregulation, oxidative stress reduction, and neuromodulation. Taurine treatments have also been shown to ameliorate the onset and development of many diseases, including hypertension, fatty liver, neurodegenerative diseases and ischemia-reperfusion injury, by exerting antioxidant, anti-inflammatory, and antiapoptotic effects. The endoplasmic reticulum (ER) is a dynamic organelle involved in a wide range of cellular functions, including lipid metabolism, calcium storage and protein stabilization. Under stress, the disruption of the ER environment leads to the accumulation of misfolded proteins and a characteristic stress response called the unfolded protein response (UPR). The UPR protects cells from stress and helps to restore cellular homeostasis, but its activation promotes cell death under prolonged ER stress. Recent studies have shown that ER stress is closely related to the onset and development of many diseases. This article reviews the beneficial effects and related mechanisms of taurine by regulating the ER in different physiological and pathological states, with the aim of providing a reference for further research and clinical applications.

Taurine deficiency associated with dilated cardiomyopathy and aging

Taurine (2-aminoethanesulfonic acid) is a free amino acid found ubiquitously and abundantly in mammalian tissues. Taurine content in the heart is approximately 20 mM, which is approximately 100 times higher than plasma concentration. The high intracellular concentration of taurine is maintained by the taurine transporter (TauT; Slc6a6). Taurine plays various roles, including the regulation of intracellular ion dynamics, calcium handling, and acting as an antioxidant in the heart. Some species, such as cats and foxes, have low taurine biosynthetic capacity, and dietary taurine deficiency can lead to disorders such as dilated cardiomyopathy and blindness. In humans, the relationship between dietary taurine deficiency and cardiomyopathy is not yet clear, but a genetic mutation related to the taurine transporter has been reported to be associated with dilated cardiomyopathy. On the other hand, many studies have shown an association between dietary taurine intake and age-related diseases. Notably, it has recently been reported that taurine declines with age and is associated with lifespan in worms and mice, as well as healthspan in mice and monkeys. In this review, we summarize the role of dietary and genetic taurine deficiency in the development of cardiomyopathy and aging.

Combination of Taurine and Black Pepper Extract as a Treatment for Cardiovascular and Coronary Artery Diseases

The shift in modern dietary regimens to "Western style" and sedentary lifestyles are believed to be partly responsible for the increase in the global burden of cardiovascular diseases. Natural products have been used throughout human history as treatments for a plethora of pathological conditions. Taurine and, more recently, black pepper have gained attention for their beneficial health effects while remaining non-toxic even when ingested in excess. Taurine, black pepper, and the major terpene constituents found in black pepper (i.e., β-caryophyllene; α-pinene; β-pinene; α-humulene; limonene; and sabinene) that are present in PhytoCann BP^® have been shown to have cardioprotective effects based on anti-inflammatory, antioxidative, anti-hypertensive and anti-atherosclerotic mechanisms. This comprehensive review of the literature focuses on determining whether the combination of taurine and black pepper extract is an effective natural treatment for reducing cardiovascular diseases risk factors (i.e., hypertension and hyperhomocysteinemia) and for driving anti-inflammatory, antioxidative and anti-atherosclerotic mechanisms to combat coronary artery disease, heart failure, myocardial infarction, and atherosclerotic disease.

Metabolomic Profiling of Brain Protective Effect of Edaravone on Cerebral Ischemia-Reperfusion Injury in Mice

Edaravone (EDA) injection has been extensively applied in clinics for treating stroke. Nevertheless, the metabolite signatures and underlying mechanisms associated with EDA remain unclear, which deserve further elucidation for improving the accurate usage of EDA. Ischemia stroke was simulated by intraluminal occlusion of the right middle cerebral artery for 1 h, followed by reperfusion for 24 h in mice. Brain infarct size, neurological deficits, and lactate dehydrogenase (LDH) levels were improved by EDA. Significantly differential metabolites were screened with untargeted metabolomics by cross-comparisons with pre- and posttreatment of EDA under cerebral ischemia/reperfusion (I/R) injury. The possibly involved pathways, such as valine, leucine, and isoleucine biosynthesis, and phenylalanine, taurine, and hypotaurine metabolisms, were enriched with differential metabolites and relevant regulatory enzymes, respectively. The network of differential metabolites was constructed for the integral exhibition of metabolic characteristics. Targeted analysis of taurine, an important metabolic marker, was performed for further validation. The level of taurine decreased in the MCAO/R group and increased in the EDA group. The inhibition of EDA on cerebral endothelial cell apoptosis was confirmed by TdT-mediated dUTP nick-end labeling (TUNEL) stain. Cysteine sulfinic acid decarboxylase (CSAD), the rate-limiting enzyme of taurine generation, significantly increased along with inhibiting endothelial cell apoptosis after treatment of EDA. Thus, CSAD, as the possible new therapeutic target of EDA, was selected and validated by Western blot and immunofluorescence. Together, this study provided the metabolite signatures and identified CSAD as an unrecognized therapeutic intervention for EDA in the treatment of ischemic stroke via inhibiting brain endothelial cell apoptosis.

Recent insights into the molecular regulators and mechanisms of taurine to modulate lipid metabolism: a review

Lipid metabolism disorders such as hypertriglyceridemia and hypercholesterolemia are risk factors for cardiovascular diseases and atherosclerosis that are grave public health issues. Taurine, a sulfur-containing non-essential amino acid exerts a wide range of physiological effects that regulate lipid metabolic disorders. Although the effects of taurine on lipid-lowering have been reported in animals and humans, mechanisms elucidating the lipid-lowering action of taurine remain unclear. A series of molecular regulators associated with lipid metabolism have been identified in the past few decades. These include nuclear receptors, transcription factors, and enzymes that undergo important changes during taurine treatment. In this review, we focus on the role of taurine in lipid metabolism and discuss taurine-related interventions in combating lipid disorders.

The Pathogenic Role of Foam Cells in Atherogenesis: Do They Represent Novel Therapeutic Targets?

BACKGROUND

Foam cells, mainly derived from monocytes-macrophages, contain lipid droplets essentially composed of cholesterol in their cytoplasm. They infiltrate the intima of arteries, contributing to the formation of atherosclerotic plaques.

PATHOGENESIS

Foam cells damage the arterial cell wall via the release of proinflammatory cytokines, free radicals, and matrix metalloproteinases, enhancing the plaque size up to its rupture.

THERAPY

A correct dietary regimen seems to be the most appropriate therapeutic approach to minimize obesity, which is associated with the formation of foam cells. At the same time, different types of antioxidants have been evaluated to arrest the formation of foam cells, even if the results are still contradictory. In any case, a combination of antioxidants seems to be more efficient in the prevention of atherosclerosis.

Taurine as a Natural Antioxidant: From Direct Antioxidant Effects to Protective Action in Various Toxicological Models

Natural antioxidants have received tremendous attention over the last 3 decades. At the same time, the attitude to free radicals is slowly changing, and their signalling role in adaptation to stress has recently received a lot of attention. Among many different antioxidants in the body, taurine (Tau), a sulphur-containing non-proteinogenic β-amino acid, is shown to have a special place as an important natural modulator of the antioxidant defence networks. Indeed, Tau is synthesised in most mammals and birds, and the Tau requirement is met by both synthesis and food/feed supply. From the analysis of recent data, it could be concluded that the direct antioxidant effect of Tau due to scavenging free radicals is limited and could be expected only in a few mammalian/avian tissues (e.g., heart and eye) with comparatively high (>15-20 mM) Tau concentrations. The stabilising effects of Tau on mitochondria, a prime site of free radical formation, are characterised and deserve more attention. Tau deficiency has been shown to compromise the electron transport chain in mitochondria and significantly increase free radical production. It seems likely that by maintaining the optimal Tau status of mitochondria, it is possible to control free radical production. Tau's antioxidant protective action is of great importance in various stress conditions in human life, and is related to commercial animal and poultry production. In various in vitro and in vivo toxicological models, Tau showed AO protective effects. The membrane-stabilizing effects, inhibiting effects on ROS-producing enzymes, as well as the indirect AO effects of Tau via redox balance maintenance associated with the modulation of various transcription factors (e.g., Nrf2 and NF-κB) and vitagenes could also contribute to its protective action in stress conditions, and thus deserve more attention.

Clinical Utility of Serum Holotranscobalamin Measurements in Patients with First-Ever Ischemic Stroke

Background

Whether holotranscobalamin (holoTC) indicates B12 deficiency more sensitively than total vitamin B12 (B12) is unclear. This study is aimed at determining the impact of serum holoTC level as a risk factor for ischemic stroke and investigating its association with disease severity and short-term outcomes.

Methods

Serum holoTC, total B12, and homocysteine levels were compared between 130 stroke patients and 138 healthy controls. Biomarker level correlations with disease severity and stroke functional outcomes were investigated.

Results

holoTC levels were lower and homocysteine levels were higher in stroke patients than in healthy controls (P < 0.05). The holoTC/total B12 ratio and homocysteine level significantly predicted ischemic stroke in the multivariable regression analysis (P < 0.05). Along with hyperhomocysteinemia, patients more often had holoTC than total B12 deficiency (6.2% vs. 3.1%). holoTC levels negatively correlated with homocysteine levels (partial R -0.165, P < 0.05) in stroke patients in multiple linear regression analyses, but not total B12 levels. The holoTC level and holoTC/total B12 ratio, but not homocysteine and total B12 levels, negatively correlated with the National Institute of Health Stroke Scale (partial R, -0.405 and -0.207, respectively, P < 0.01).

Conclusions

Measurements of serum holoTC levels combined with total B12 and homocysteine levels may provide valuable information for predicting ischemic stroke and its severity and short-term outcomes of ischemic stroke patients.

Review - Nutraceuticals Can Target Asthmatic Bronchoconstriction: NADPH Oxidase-Dependent Oxidative Stress, RhoA and Calcium Dynamics

Activation of various isoforms of NADPH oxidase contributes to the pathogenesis of asthma at multiple levels: promoting hypercontractility, hypertrophy, and proliferation of airway smooth muscle; enabling lung influx of eosinophils via VCAM-1; and mediating allergen-induced mast cell activation. Free bilirubin, which functions physiologically within cells as a feedback inhibitor of NADPH oxidase complexes, has been shown to have a favorable impact on each of these phases of asthma pathogenesis. The spirulina chromophore phycocyanobilin (PhyCB), a homolog of bilirubin’s precursor biliverdin, can mimic the inhibitory impact of biliverdin/bilirubin on NADPH oxidase activity, and spirulina’s versatile and profound anti-inflammatory activity in rodent studies suggests that PhyCB may have potential as a clinical inhibitor of NADPH oxidase. Hence, spirulina or PhyCB-enriched spirulina extracts merit clinical evaluation in asthma. Promoting biosynthesis of glutathione and increasing the expression and activity of various antioxidant enzymes – as by supplementing with N-acetylcysteine, Phase 2 inducers (eg, lipoic acid), selenium, and zinc – may also blunt the contribution of oxidative stress to asthma pathogenesis. Nitric oxide (NO) and hydrogen sulfide (H₂S) work in various ways to oppose pathogenic mechanisms in asthma; supplemental citrulline and high-dose folate may aid NO synthesis, high-dose biotin may mimic and possibly potentiate NO’s activating impact on soluble guanylate cyclase, and NAC and taurine may boost H₂S synthesis. The amino acid glycine has a hyperpolarizing effect on airway smooth muscle that is bronchodilatory. Insuring optimal intracellular levels of magnesium may modestly blunt the stimulatory impact of intracellular free calcium on bronchoconstriction. Nutraceutical regimens or functional foods incorporating at least several of these agents may have utility as nutraceutical adjuvants to standard clinical management of asthma.

Synergistic effects of black ginseng and aged garlic extracts for the amelioration of nonalcoholic fatty liver disease (NAFLD) in mice

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease that can lead to carcinoma, cirrhosis, and death. Since no approved medications are available, dietary interventions that include bioactive compounds have been recommended. This study investigated the effects of black ginseng extracts (BGE) and aged black garlic extracts (AGE) on high-fat diet (HFD)-induced obese mice. Micrograph of liver tissues of mice fed with BGE and AGE showed less lipid droplets. The BGE and AGE supplements individually and in combination lowered the marker enzymes, aminotransferase (AST), and alanine aminotransferase (ALT) levels indicating their hepatoprotective effects. Compared to the plants extracts alone, the combination of the extracts resulted in lower total cholesterol (TC) and low-density lipoproteins cholesterol (LDL-C), which are risk markers for cardiovascular morbidity and mortality. Diets with the combination of BGE and AGE supplements had higher superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities, and lower malondialdehyde indicating the synergistic effects of the extracts. Irrespective of the diet type, all treated groups showed lower tumor necrosis factor (TNF-α) values as compared to HFD, which indicated overall immunomodulatory effect of both extracts. Therefore, the innovative formulation formed by the combination of BGE and AGE can provide hepatoprotective effects via modulating glycometabolism, lipometabolism, oxidative stress, and inflammation in mice.

Diminazene Aceturate Stabilizes Atherosclerotic Plaque and Attenuates Hepatic Steatosis in apoE-Knockout Mice by Influencing Macrophages Polarization and Taurine Biosynthesis

Atherosclerosis and nonalcoholic fatty liver disease are leading causes of morbidity and mortality in the Western countries. The renin-angiotensin system (RAS) with its two main opposing effectors, i.e., angiotensin II (Ang II) and Ang-(1-7), is widely recognized as a major regulator of cardiovascular function and body metabolic processes. Angiotensin-converting enzyme 2 (ACE2) by breaking-down Ang II forms Ang-(1-7) and thus favors Ang-(1-7) actions. Therefore, the aim of our study was to comprehensively evaluate the influence of prolonged treatment with ACE2 activator, diminazene aceturate (DIZE) on the development of atherosclerotic lesions and hepatic steatosis in apoE-/- mice fed a high-fat diet (HFD). We have shown that DIZE stabilized atherosclerotic lesions and attenuated hepatic steatosis in apoE-/- mice fed an HFD. Such effects were associated with decreased total macrophages content and increased α-smooth muscle actin levels in atherosclerotic plaques. Moreover, DIZE changed polarization of macrophages towards increased amount of anti-inflammatory M2 macrophages in the atherosclerotic lesions. Interestingly, the anti-steatotic action of DIZE in the liver was related to the elevated levels of HDL in the plasma, decreased levels of triglycerides, and increased biosynthesis and concentration of taurine in the liver of apoE-/- mice. However, exact molecular mechanisms of both anti-atherosclerotic and anti-steatotic actions of DIZE require further investigations.

The molecular targets of taurine confer anti-hyperlipidemic effects

Hyperlipidemia, an independent risk factor for atherosclerosis, is regarded as a lipid metabolism disorder associated with elevated plasma triglyceride and/or cholesterol. Genetic factors and unhealthy lifestyles, such as excess caloric intake and physical inactivity, can result in hyperlipidemia. Taurine, a sulfur-containing non-essential amino acid, is abundant in marine foods and has been associated with wide-ranging beneficial physiological effects, with special reference to regulating aberrant lipid metabolism. Its anti-hyperlipidemic mechanism is complex, which is related to many enzymes in the process of fat anabolism and catabolism (e.g., HMGCR, CYP7A1, LDLR, FXR, FAS and ACC). Anti-inflammatory and antioxidant molecular targets, lipid autophagy, metabolic reprogramming and gut microbiota will also be reviewed.

Nutraceutical, Dietary, and Lifestyle Options for Prevention and Treatment of Ventricular Hypertrophy and Heart Failure

Although well documented drug therapies are available for the management of ventricular hypertrophy (VH) and heart failure (HF), most patients nonetheless experience a downhill course, and further therapeutic measures are needed. Nutraceutical, dietary, and lifestyle measures may have particular merit in this regard, as they are currently available, relatively safe and inexpensive, and can lend themselves to primary prevention as well. A consideration of the pathogenic mechanisms underlying the VH/HF syndrome suggests that measures which control oxidative and endoplasmic reticulum (ER) stress, that support effective nitric oxide and hydrogen sulfide bioactivity, that prevent a reduction in cardiomyocyte pH, and that boost the production of protective hormones, such as fibroblast growth factor 21 (FGF21), while suppressing fibroblast growth factor 23 (FGF23) and marinobufagenin, may have utility for preventing and controlling this syndrome. Agents considered in this essay include phycocyanobilin, N-acetylcysteine, lipoic acid, ferulic acid, zinc, selenium, ubiquinol, astaxanthin, melatonin, tauroursodeoxycholic acid, berberine, citrulline, high-dose folate, cocoa flavanols, hawthorn extract, dietary nitrate, high-dose biotin, soy isoflavones, taurine, carnitine, magnesium orotate, EPA-rich fish oil, glycine, and copper. The potential advantages of whole-food plant-based diets, moderation in salt intake, avoidance of phosphate additives, and regular exercise training and sauna sessions are also discussed. There should be considerable scope for the development of functional foods and supplements which make it more convenient and affordable for patients to consume complementary combinations of the agents discussed here. Research Strategy: Key word searching of PubMed was employed to locate the research papers whose findings are cited in this essay.

Lactic acid bacteria prevent both periodontitis and atherosclerosis exacerbated by periodontitis in spontaneously hyperlipidemic mice

BACKGROUND AND OBJECTIVE

Recent studies have shown a link between periodontal disease and cardiovascular disease. We have previously reported that oral administration of Porphyromonas gingivalis (Pg) accelerates atherosclerosis in apolipoprotein E-deficient spontaneously hyperlipidemic (Apoe^shl ) mice. This study evaluated the potential of lactic acid bacteria (LAB) to change the intestinal flora changes induced by periodontopathic bacteria and to prevent/slow down the development of atherosclerosis.

METHODS

Lactobacillus gasseri O3-2 (Lg) was orally intubated in Apoe^shl mice for 5 weeks. Three weeks after oral intubation, the mice were orally infected with Pg for 2 weeks.

RESULTS

Thirty days after the last infection with Pg, Lg+Pg-treated mice showed a significant reduction in alveolar bone loss compared to the Pg-treated group. The Lg treatment restored the Pg-induced intestinal flora disturbance to normal. Furthermore, a significant decrease in atherosclerotic plaque lesion size and suppressed inflammatory cytokine production in the aorta were detected in the Lg + Pg-treated group. In contrast, blood concentrations of TMAO, histidine, and carnitine were enhanced by the Lg treatment but decreased by Lg + Pg treatment.

CONCLUSION

These results suggest that oral Lg treatment is effective in preventing periodontitis and atherosclerosis.

Metabolic Syndrome and Its Components Are Associated With Altered Amino Acid Profile in Chinese Han Population

OBJECTIVE

Recent studies have found that the levels of plasma amino acids, such as branched-chain amino acids and aromatic amino acids, were associated with visceral obesity, insulin resistance, future development of diabetes and cardiovascular diseases. However, few studies have involved a Chinese Han population. This study aimed to examine the association between amino acid profile and metabolic syndrome (MetS) and its components in the Chinese Han population.

METHODS

This is a cross-sectional study, which enrolled a cohort of 473 participants from a community. We employed the isotope internal standard method to determine the plasma concentrations of 28 amino acids using high-performance liquid chromatography-tandem mass spectrometry (LC/MS). Participants were divided into MetS (n = 72) and non-MetS groups (n = 401) to analyze the association between amino acids and MetS and its components.

RESULTS

The prevalence of MetS was 15.2% according to the criteria. Plasma concentrations of isoleucine (Ile), leucine (Leu), valine (Val), tyrosine (Tyr), tryptophan (Trp), phenylalanine (Phe), glutamic acid (Glu), aspartic acid (Asp), alanine (Ala), histidine (His), methionine (Met), asparagine (Asn), and proline (Pro) were significantly higher in the MetS group than those in the non-MetS group (P < 0.05), but taurine (Tau) was significantly lower (P < 0.05). When MetS components were increased, the concentrations of these 13 amino acids significantly increased (P < 0.05), but Tau concentration was significantly decreased (P < 0.05). We extracted the amino acid profile by principal component analysis (PCA), PC1 and PC2, which extracted from the 14 amino acids, were significantly associated with MetS (odds ratio, 95% confidence interval: 1.723, 1.325-2.085 and 1.325, 1.043-1.684, respectively). A total of 260 non-MetS participants were followed up effectively, and 42 participants developed new-onset MetS within 5 years. We found that the amino acid profile of PC1 was linked to the occurrence of future MetS. Decreased Tau was correlated with the future development of MetS.

CONCLUSION

Participants with MetS exhibit an abnormal amino acid profile, and its components gradually increase when these amino acids are altered. Amino acid PCA profile can be employed for assessing and monitoring MetS risk. Finally, decreased Tau may be linked to the future development of MetS.

Myeloperoxidase: A versatile mediator of endothelial dysfunction and therapeutic target during cardiovascular disease

Myeloperoxidase (MPO) is a prominent mammalian heme peroxidase and a fundamental component of the innate immune response against microbial pathogens. In recent times, MPO has received considerable attention as a key oxidative enzyme capable of impairing the bioactivity of nitric oxide (NO) and promoting endothelial dysfunction; a clinically relevant event that manifests throughout the development of inflammatory cardiovascular disease. Increasing evidence indicates that during cardiovascular disease, MPO is released intravascularly by activated leukocytes resulting in its transport and sequestration within the vascular endothelium. At this site, MPO catalyzes various oxidative reactions that are capable of promoting vascular inflammation and impairing NO bioactivity and endothelial function. In particular, MPO catalyzes the production of the potent oxidant hypochlorous acid (HOCl) and the catalytic consumption of NO via the enzyme's NO oxidase activity. An emerging paradigm is the ability of MPO to also influence endothelial function via non-catalytic, cytokine-like activities. In this review article we discuss the implications of our increasing knowledge of the versatility of MPO's actions as a mediator of cardiovascular disease and endothelial dysfunction for the development of new pharmacological agents capable of effectively combating MPO's pathogenic activities. More specifically, we will (i) discuss the various transport mechanisms by which MPO accumulates into the endothelium of inflamed or diseased arteries, (ii) detail the clinical and basic scientific evidence identifying MPO as a significant cause of endothelial dysfunction and cardiovascular disease, (iii) provide an up-to-date coverage on the different oxidative mechanisms by which MPO can impair endothelial function during cardiovascular disease including an evaluation of the contributions of MPO-catalyzed HOCl production and NO oxidation, and (iv) outline the novel non-enzymatic mechanisms of MPO and their potential contribution to endothelial dysfunction. Finally, we deliver a detailed appraisal of the different pharmacological strategies available for targeting the catalytic and non-catalytic modes-of-action of MPO in order to protect against endothelial dysfunction in cardiovascular disease.

Effects of the Suxiao Jiuxin pill on acute myocardial infarction assessed by comprehensive metabolomics

BACKGROUND

SJP is the commercial Chinese medicine included in the Chinese Pharmacopoeia, with well-established cardiovascular protective effects in the clinic. However, the mechanisms underlying the protective effects of SJP on cardiovascular disease have not yet been clearly elucidated.

AIMS

To investigate the underlying protective mechanisms of SJP in an acute myocardial infarction (AMI) rat model using comprehensive metabolomics.

MATERIALS AND METHODS

The rat model of AMI was generated by ligating the left anterior descending coronary artery. After 2 weeks treatment with SJP, the entire metabolic changes in the serum, heart, urine and feces of the rat were profiled by HPLC-QTOF-MS/MS.

RESULTS

The metabolic profiles in different biological samples (heart, serum, urine and feces) were significantly different among groups, in which a total of 112 metabolites were identified. AMI caused comprehensive metabolic changes in amino acid metabolism, galactose metabolism and fatty acid metabolism, while SJP reversed more than half of the differential metabolic changes, mainly affecting amino acid metabolism and fatty acid metabolism. Correlation analysis found that SJP could significantly alter the metabolic activity of 12 key metabolites, regarded as potential biomarkers of SJP treatment. According to the results of network analysis, 6 biomarkers were considered to be hub metabolites, which means that these metabolites may have a major relationship with the SJP therapeutic effects on AMI.

CONCLUSION

The combined comprehensive metabolomics and network analysis, indicated that the protective effect of SJP on cardiovascular disease was associated with systemic metabolic modulation, in particular regulation of amino acid and fatty acid metabolism.

Sulfur-Containing Amino Acids and Lipid Metabolism

The metabolism of methionine and cysteine in the body tissues determines the concentrations of several metabolites with various biologic activities, including homocysteine, hydrogen sulfide (H2S), taurine, and glutathione. Hyperhomocysteinemia, which is correlated with lower HDL cholesterol in blood in volunteers and animal models, has been associated with an increased risk for cardiovascular diseases. In humans, the relation between methionine intake and hyperhomocysteinemia is dependent on vitamin status (vitamins B-6 and B-12 and folic acid) and on the supply of other amino acids. However, lowering homocysteinemia by itself is not sufficient for decreasing the risk of cardiovascular disease progression. Other compounds related to methionine metabolism have recently been identified as being involved in the risk of atherosclerosis and steatohepatitis. Indeed, the metabolism of sulfur amino acids has an impact on phosphatidylcholine (PC) metabolism, and anomalies in PC synthesis due to global hypomethylation have been associated with disturbances of lipid metabolism. In addition, impairment of H2S synthesis from cysteine favors atherosclerosis and steatosis in animal models. The effects of taurine on lipid metabolism appear heterogeneous depending on the populations of volunteers studied. A decrease in the concentration of intracellular glutathione, a tripeptide involved in redox homeostasis, is implicated in the etiology of cardiovascular diseases and steatosis. Last, supplementation with betaine, a compound that allows remethylation of homocysteine to methionine, decreases basal and methionine-stimulated homocysteinemia; however, it adversely increases plasma total and LDL cholesterol. The study of these metabolites may help determine the range of optimal and safe intakes of methionine and cysteine in dietary proteins and supplements. The amino acid requirement for protein synthesis in different situations and for optimal production of intracellular compounds involved in the regulation of lipid metabolism also needs to be considered for dietary attenuation of atherosclerosis and steatosis risk.

Free Amino Acids and Biogenic Amines in Canned European Eels: Influence of Processing Step, Filling Medium and Storage Time

This study evaluated the effects of the canning process and different filling media on the free amino acid and biogenic amine contents of eels. The main free amino acids were histidine, taurine and arginine, which constituted 72% of the free amino acids in raw eels. All steps in the canning process significantly altered the free amino acid content of eels, relative to raw samples. The changes were influenced by the step, the composition of the frying or filling medium and the storage time. The biogenic amine contents were very low in all samples. Histamine was not detected in either raw eels or canned eels. The highest values were obtained for 2-phenylethylamine. The step of the canning process, the composition of the frying or filling medium and storage time also determined the changes in the biogenic amine contents. The biogenic amines indices were low, indicating the good quality of canned eels.

Nutritional characteristics of marine fish Sardinella zunasi Bleeker and immunostimulatory activities of its glycoprotein

Sardinella zunasi Bleeker, an edible and medicinal marine fish, is largely distributed in tropical oceans. However, the chemical composition and nutritional properties of this species have not yet been investigated. In the present study, proximate composition, fatty acids, amino acids, taurine, and minerals of S. zunasi Bleeker were characterized, and the immunostimulatory properties of its glycoprotein were evaluated. The results indicated the presence of crude protein (19.66%), crude lipid (6.29%) and carbohydrate (0.74%) in S. zunasi Bleeker; monounsaturated fatty acids and polyunsaturated fatty acids in the fatty acid composition of S. zunasi Bleeker were 25.00% and 31.01%, respectively; S. zunasi Bleeker was rich in taurine (219 mg/100 g) and essential amino acids (5.57 g/100 g). In addition, the glycoprotein of S. zunasi consisted of protein and sugars, with a total content of 34.25% and 16.27%, respectively. The glycoprotein showed significant effects on promoting NO, TNF-α and IL-6 in a dose-dependent manner in RAW264.7 macrophage cells. Thus, these findings provide a scientific basis for the further utilization of glycoprotein from S. zunasi Bleeker.

Lipid Profile Changes Induced by Chronic Administration of Anabolic Androgenic Steroids and Taurine in Rats

Background and Objectives: Anabolic androgenic steroids (AAS), used as a therapy in various diseases and abused in sports, are atherogenic in supraphysiological administration, altering the plasma lipid profile. Taurine, a conditionally-essential amino acid often used in dietary supplements, was acknowledged to delay the onset and progression of atherogenesis, and to mitigate hyperlipidemia. The aim of the present study was to verify if taurine could prevent the alterations induced by concomitant chronic administration of high doses of AAS nandrolone decanoate (DECA) in rats. Materials and Methods: Thirty-two male Wistar rats, assigned to 4 equal groups, were treated for 12 weeks either with DECA (A group), taurine (T group), both DECA and taurine (AT group) or vehicle (C group). Plasma triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), hepatic triglycerides (TGh) and liver non-esterified fatty acids (NEFA) were then determined. Results: DECA elevated TG level in A group vs. control (p = 0.01), an increase prevented by taurine association in AT group (p = 0.04). DECA decreased HDL-C in A group vs. control (p = 0.02), while taurine tended to increase it in AT group. DECA decreased TGh (p = 0.02) in A group vs. control. Taurine decreased TGh in T (p = 0.004) and AT (p < 0.001) groups vs. control and tended to lower NEFA (p = 0.08) in AT group vs. A group. Neither DECA, nor taurine influenced TC and LDL-C levels. Conclusions: Taurine partially prevented the occurrence of DECA negative effects on lipid profile, suggesting a therapeutic potential in several conditions associated with chronic high levels of plasma androgens, such as endocrine disorders or AAS-abuse.

Comparison of Mechanisms of Endothelial Cell Protections Between High-Density Lipoprotein and Apolipoprotein A-I Mimetic Peptide

Apolipoprotein A-I (apoA-I) mimetic peptide, D-4F, exhibits anti-atherogenic effects similar to high-density lipoprotein (HDL). However, it remains elusive whether D-4F and HDL share similar molecular mechanisms underlying anti-atherogenic effects and endothelial cell protections. We here compared the metabolic changes in endothelial cells induced by D-4F and HDL against oxidized low-density lipoprotein (ox-LDL), which may be of benefit to understanding the protective mechanisms of HDL and D-4F. Functional assays, including wound healing, transwell migration, and tube formation, were used to evaluate the pro-angiogenic effects of HDL and D-4F. NMR-based metabolomic analysis was employed to explore the protective mechanisms underlying HDL and D-4F. Partial least-squares discriminant analysis (PLS-DA) was performed to assess metabolic profiles, and orthogonal PLS-DA (OPLS-DA) was carried out to identify characteristic metabolites. Moreover, significantly altered metabolic pathways were also analyzed. We found that ox-LDL impaired the migration and tube formation of endothelial cells. Metabolomic analysis showed that ox-LDL triggered oxidative stress, impaired glycolysis, and enhanced glycerophospholipid metabolism. Both HDL and D-4F improved the migration and angiogenesis of endothelial cells, alleviated oxidative stress, and ameliorated disordered glycolysis impaired by ox-LDL. Strikingly, HDL partially attenuated the disturbed glycerophospholipid metabolism, whereas D-4F did not show this effect. In summary, although D-4F shared the similar protective effects with HDL on the migration and angiogenesis of endothelial cells, it could not deduce the molecular mechanisms of HDL completely. Nevertheless, D-4F possesses the potentiality to be exploited as clinically applicable agent for endothelial cell protection and cardiovascular disease treatment.

American Ginseng and Asian Ginseng Intervention in Diet-Induced Obese Mice: Metabolomics Reveals Distinct Metabolic Profiles

American ginseng and Asian ginseng, which occupy prominent positions in the list of best-selling natural products in the West and East, are suitable for different indications in the traditional pharmacological uses. Currently, the effects of American ginseng and Asian ginseng in the protection against metabolic dysfunction and the differences between them are still unknown. Herein, an untargeted metabolomics based on liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) was determined. The serum metabolomics and dynamic feces metabolomics revealed significant metabolic distinction between American ginseng and Asian ginseng in diet-induced obese (DIO) mice. The results show that American ginseng and Asian ginseng alleviate glucose and lipid metabolism disorder in DIO mice. A total of 45 differential metabolites were confirmed between the drug-naïve and American ginseng group, and 32 metabolites were confirmed between the drug-naïve and Asian ginseng group. Metabolic pathways analysis shows that these two ginsengs treatment dynamic rectifies metabolic disorder in DIO mice mainly via regulating linoleic acids metabolism, cysteine and methionine metabolism and biosynthesis of unsaturated fatty acid. Moreover, American ginseng's specific function in monitoring the carnitines and taurine/hypotaurine metabolism might make it more effective in meliorating lipids metabolism disorder than Asian ginseng.

Effect of Taurine on Intestinal Microbiota and Immune Cells in Peyer's Patches of Immunosuppressive Mice

Taurine is a sulfur-containing amino acid which has strong activities in enhancing immunity. Gut microbiota is closely interrelated with intestinal mucosal immunity, but the effects and mechanisms of taurine on intestinal microbiota and mucosal immune cells under an immunosuppressive condition remain unclear. This study was conducted to investigate the effect of taurine on gut microbiota and immune cells in Peyer's patches (PPs) of dexamethasone (Dex)-induced immunosuppressive mice. Mice (4-week-old, Male) were randomly divided into three groups: the Control group (n = 12), the Dex-induced immunosuppressive model group (n = 12) and the taurine intervention group (n = 12). The model was established by Dex injection for 7 days and the taurine intervention group was gavaged 100 mg/kg soluble taurine for 30 days. The changes of intestinal microbiota and immune cells in PPs were tested by denaturing gradient gel electrophoresis (DGGE) and flow cytometry, respectively. Results showed that the microbiota in immunosuppressive mice was obvious different compared with control group, in which, the Lachnospiraceae and Ruminococcaceae groups were significantly reduced, and their reduction were reversed after taurine intervention. Compared to the control group, the total cell number in PPs, as well as the subsets of CD3⁺ cells (T cells), CD19⁺ cells (B cells) in model groups were significantly lower, and they were dramatically improved after taurine treatment. Our results suggested that taurine has a positive effect on i ntestinal homeostasis of the immunosuppressive mice.

Nutrients in Fish and Possible Associations with Cardiovascular Disease Risk Factors in Metabolic Syndrome

Non-communicable diseases (NSDs) are responsible for two-thirds of all deaths globally, whereas cardiovascular disease (CVD) alone counts for nearly half of them. To reduce the impact of CVD, targeting modifiable risk factors comprised in metabolic syndrome (e.g., waist circumference, lipid profile, blood pressure, and blood glucose) is of great importance. Beneficial effects of fish consumption on CVD has been revealed over the past decades, and some studies suggest that fish consumption may have a protective role in preventing metabolic syndrome. Fish contains a variety of nutrients that may contribute to health benefits. This review examines current recommendations for fish intake as a source of various nutrients (proteins, n-3 fatty acids, vitamin D, iodine, selenium, and taurine), and their effects on metabolic syndrome and the CVD risk factors. Fatty fish is recommended due to its high levels of n-3 fatty acids, however lean fish also contains nutrients that may be beneficial in the prevention of CVD.

Increased Levels of Circulating Fatty Acids Are Associated with Protective Effects against Future Cardiovascular Events in Nondiabetics

Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide, particularly in individuals with diabetes. The current study objective was to determine the circulating metabolite profiles associated with the risk of future cardiovascular events, with emphasis on diabetes status. Nontargeted metabolomics analysis was performed by LC-HRMS in combination with targeted quantification of eicosanoids and endocannabinoids. Plasma from 375 individuals from the IMPROVE pan-European cohort was included in a case-control study design. Following data processing, the three metabolite data sets were concatenated to produce a single data set of 267 identified metabolites. Factor analysis identified six factors that described 26.6% of the variability in the given set of predictors. An association with cardiovascular events was only observed for one factor following adjustment (p = 0.026). From this factor, we identified a free fatty acid signature (n = 10 lipids, including saturated, monounsaturated, and polyunsaturated fatty acids) that was associated with lower risk of future cardiovascular events in nondiabetics only (OR = 0.65, 0.27-0.80 95% CI, p = 0.030), whereas no association was observed among diabetic individuals. These observations support the hypothesis that increased levels of circulating omega-6 and omega-3 fatty acids are associated with protective effects against future cardiovascular events. However, these effects were only observed in the nondiabetic population, further highlighting the need for patient stratification in clinical investigations.

Characteristics of erythrocyte-derived microvesicles and its relation with atherosclerosis

Microvesicles are formed under many circumstances, especially in atheromatous plaques. Erythrocyte-derived microvesicles (ErMVs) have been proved to promote atherosclerosis by promoting hypercoagulation, mediating inflammation and inducing cell adhesion. Several clinical studies have reported potential roles of ErMVs in cardiovascular disease diagnosis, but the current understanding of ErMVs remains insufficient. In this paper, we will review current research on the formation and degradation of ErMVs and the possible effects of ErMVs in atherosclerosis, discuss potential clinical applications in cardiovascular disease, and hope to raise awareness of the relation with atherosclerosis.

Impact of chronic administration of anabolic androgenic steroids and taurine on blood pressure in rats

Supraphysiological administration of anabolic androgenic steroids has been linked to increased blood pressure. The widely distributed amino acid taurine seems to be an effective depressor agent in drug-induced hypertension. The purpose of this study was to assess the impact of chronic high dose administration of nandrolone decanoate (DECA) and taurine on blood pressure in rats and to verify the potentially involved mechanisms. The study was conducted in 4 groups of 8 adult male Wistar rats, aged 14 weeks, treated for 12 weeks with: DECA (A group); vehicle (C group); taurine (T group), or with both drugs (AT group). Systolic blood pressure (SBP) was measured at the beginning of the study (SBP₁), 2 (SBP₂) and 3 months (SBP₃) later. Plasma angiotensin-converting enzyme (ACE) activity and plasma end products of nitric oxide metabolism (NO_x) were also determined. SBP₃ and SBP₂ were significantly increased compared to SBP₁ only in the A group (P<0.002 for both). SBP₂, SBP₃ and ACE activity showed a statistically significant increase in the A vs C (P<0.005), andvs AT groups (P<0.05), while NO_x was significantly decreased in the A and AT groups vs controls (P=0.01). ACE activity was strongly correlated with SBP₃ in the A group (r=0.71, P=0.04). These findings suggest that oral supplementation of taurine may prevent the increase in SBP induced by DECA, an effect potentially mediated by angiotensin-converting enzyme.

The beneficial effects of taurine in preventing metabolic syndrome

A review of the data fromin vitro, animal and limited human studies of the beneficial effects of taurine on obesity, dyslipidaemia, diabetes mellitus and hypertension, as well as the possible metabolic and molecular mechanisms for the prevention of metabolic syndrome by taurine.

Sulforaphane Protects against Cardiovascular Disease via Nrf2 Activation

Cardiovascular disease (CVD) causes an unparalleled proportion of the global burden of disease and will remain the main cause of mortality for the near future. Oxidative stress plays a major role in the pathophysiology of cardiac disorders. Several studies have highlighted the cardinal role played by the overproduction of reactive oxygen or nitrogen species in the pathogenesis of ischemic myocardial damage and consequent cardiac dysfunction. Isothiocyanates (ITC) are sulfur-containing compounds that are broadly distributed among cruciferous vegetables. Sulforaphane (SFN) is an ITC shown to possess anticancer activities by both in vivo and epidemiological studies. Recent data have indicated that the beneficial effects of SFN in CVD are due to its antioxidant and anti-inflammatory properties. SFN activates NF-E2-related factor 2 (Nrf2), a basic leucine zipper transcription factor that serves as a defense mechanism against oxidative stress and electrophilic toxicants by inducing more than a hundred cytoprotective proteins, including antioxidants and phase II detoxifying enzymes. This review will summarize the evidence from clinical studies and animal experiments relating to the potential mechanisms by which SFN modulates Nrf2 activation and protects against CVD.

Impact of taurine depletion on glucose control and insulin secretion in mice

Taurine, an endogenous sulfur-containing amino acid, is found in millimolar concentrations in mammalian tissue, and its tissue content is altered by diet, disease and aging. The effectiveness of taurine administration against obesity and its related diseases, including type 2 diabetes, has been well documented. However, the impact of taurine depletion on glucose metabolism and fat deposition has not been elucidated. In this study, we investigated the effect of taurine depletion (in the taurine transporter (TauT) knockout mouse model) on blood glucose control and high fat diet-induced obesity. TauT-knockout (TauTKO) mice exhibited lower body weight and abdominal fat mass when maintained on normal chow than wild-type (WT) mice. Blood glucose disposal after an intraperitoneal glucose injection was faster in TauTKO mice than in WT mice despite lower serum insulin levels. Islet beta-cells (insulin positive area) were also decreased in TauTKO mice compared to WT mice. Meanwhile, overnutrition by high fat (60% fat)-diet could lead to obesity in TauTKO mice despite lower body weight under normal chow diet condition, indicating nutrition in normal diet is not enough for TauTKO mice to maintain body weight comparable to WT mice. In conclusion, taurine depletion causes enhanced glucose disposal despite lowering insulin levels and lower body weight, implying deterioration in tissue energy metabolism.

1H-NMR-based metabolomic analysis of cerebrospinal fluid from adult bilateral moyamoya disease: comparison with unilateral moyamoya disease and atherosclerotic stenosis

Although metabolomics has been increasingly used to observe metabolic pattern and disease-specific metabolic markers, metabolite profiling for moyamoya disease (MMD) has not yet been done in adults. This study investigated cerebrospinal fluid (CSF) metabolites specific to bilateral MMD (B-MMD) and compared them to those of unilateral MMD (U-MMD) or atherosclerotic stenosis with hydrogen-1 nuclear magnetic resonance spectroscopy to identify metabolic biomarkers associated with MMD in adults.CSF samples of B-MMD (n = 29), U-MMD (n = 11), and atherosclerotic cerebrovascular disease (ACVD) (n = 8) were recruited. Principal component analysis, partial least square discriminant analysis, and orthogonal projections to latent structure discriminant analysis (OPLS-DA) were done for the comparisons. Diagnostic performance was acquired by prediction of 1 left-out sample from the distinction model constructed with the rest of the samples.B-MMD showed an increase in glutamine (P < 0.001) and taurine (P = 0.004), and a decrease in glucose (P < 0.001), citrate (P = 0.002), and myo-inositol (P = 0.006) than those in ACVD. U-MMD showed a higher level of glutamine (P = 0.005) and taurine (P = 0.034), and a lower level of glutamate (P < 0.004) than those in ACVD. No difference at the metabolite level was observed between B-MMD and U-MMD. Cross-validation with the OPLS-DA model showed a high accuracy for the prediction of MMD.The results of the study suggest that a metabolomics approach may be helpful in confirming MMD and providing a better understanding of MMD pathogenesis. Elevated glutamine in the CSF may be associated with MMD pathogenesis, which was different from ACVD.

Role of the osmolyte taurine on the folding of a model protein, hen egg white lysozyme, under a crowding condition

Taurine is one of the osmolytes that maintain the structure of proteins in cells exposed to denaturing environmental stressors. Recently, cryoelectron tomographic analysis of eukaryotic cells has revealed that their cytoplasms are crowded with proteins. Such crowding conditions would be expected to hinder the efficient folding of nascent polypeptide chains. Therefore, we examined the role of taurine on the folding of denatured and reduced lysozyme, as a model protein, under a crowding condition. The results confirmed that taurine had a better effect on protein folding than did β-alanine, which has a similar chemical structure, when the protein to be folded was present at submillimolar concentration. NMR analyses further revealed that under the crowding condition, taurine had more interactions than did β-alanine with the lysozyme molecule in both the folded and denatured states. We concluded that taurine improves the folding of the reduced lysozyme at submillimolar concentration to allow it to interact more favorably with the lysozyme molecule. Thus, the role of taurine, as an osmolyte in vivo, may be to assist in the efficient folding of proteins.

Practical strategies for modulating foam cell formation and behavior

Although high density lipoprotein (HDL)-mediated reverse cholesterol transport is crucial to the prevention and reversal of atheroma, a recent meta-analysis makes evident that current pharmaceutical strategies for modulating HDL cholesterol levels lower cardiovascular risk only to the extent that they concurrently decrease low density lipoprotein (LDL) cholesterol. This corresponds well with findings of a recent Mendelian randomization analysis, in which genetic polymorphisms associated with HDL cholesterol but no other known cardiovascular risk factors failed to predict risk for myocardial infarction. Although it is still seems appropriate to search for therapies that could improve the efficiency with which HDL particles induce reverse cholesterol transport, targeting HDL cholesterol levels per se with current measures appears to be futile. It may therefore be more promising to promote reverse cholesterol transport with agents that directly target foam cells. Macrophage expression of the cholesterol transport proteins adenosine triphosphate binding cassette transporter A1, adenosine triphosphate binding cassette transporter G1, and scavenger receptor class B member 1 is transcriptionally up-regulated by activated liver X receptors (LXR), whereas nuclear factor (NF)-kappaB antagonizes their expression. Taurine, which inhibits atherogenesis in rodent studies, has just been discovered to act as a weak agonist for LXRalpha. Conversely, it may be possible to oppose NF-kappaB activation in macrophages with a range of measures. Induction of heme oxygenase-1, which can be attained with phase 2 inducer phytochemicals such as lipoic acid and green tea catechins, promotes reverse cholesterol transport in macrophages and inhibits atherogenesis in rodents, likely due to, in large part, NF-kappaB antagonism. Inhibition of macrophage nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity with the spirulina-derived bilirubin-mimetic phycocyanobilin may also oppose NF-kappaB activation, and salicylic acid similarly should be useful for this purpose. The 5' adenosine monophosphate-activated protein kinase activator berberine promotes macrophage reverse cholesterol transport in cell culture; metformin probably shares this property. Many of these measures could also be expected to promote plaque stability by suppressing foam cell production of inflammatory cytokines and matrix metalloproteinases, and to reduce intimal monocyte infiltration by anti-inflammatory effects on vascular endothelium. Direct targeting of foam cells with agents such as phase 2 inducers, spirulina, salicylate, taurine, and berberine or metformin, may hence have considerable potential for preventing and reversing atheroma, and for preventing the plaque rupture that triggers vascular thrombosis.

Neuroprotective Mechanisms of Taurine against Ischemic Stroke

Ischemic stroke exhibits a multiplicity of pathophysiological mechanisms. To address the diverse pathophysiological mechanisms observed in ischemic stroke investigators seek to find therapeutic strategies that are multifaceted in their action by either investigating multipotential compounds or by using a combination of compounds. Taurine, an endogenous amino acid, exhibits a plethora of physiological functions. It exhibits antioxidative properties, stabilizes membrane, functions as an osmoregulator, modulates ionic movements, reduces the level of pro-inflammators, regulates intracellular calcium concentration; all of which contributes to its neuroprotective effect. Data are accumulating that show the neuroprotective mechanisms of taurine against stroke pathophysiology. In this review, we describe the neuroprotective mechanisms employed by taurine against ischemic stroke and its use in clinical trial for ischemic stroke.