Selenium in the prevention of atherosclerosis and its underlying mechanisms

Selenium nanoparticles inhibit the formation of atherosclerosis in apolipoprotein E deficient mice by alleviating hyperlipidemia and oxidative stress

Atherosclerosis can cause severe cardiovascular diseases, which is the most common cause of death in the world. It's of great significance to study the prevention and treatment of atherosclerosis. Selenium nanoparticles (SeNPs) has drawn more and more attention due to high biological activity, high bioavailability, strong antioxidant capacity and low toxicity, exhibiting great potential in biomedical application. Thus, this study aimed at explore the anti-atherosclerotic effect of two kinds of SeNPs, bovine serum albumin (BSA) surface-decorated SeNPs and chitosan (CS) surface-decorated SeNPs (CS-SeNPs), in apolipoprotein E deficient (ApoE-/-) mice fed with a high-cholesterol and high-fat diet, and the possible mechanisms. The results demonstrated that both BSA-SeNPs (25, 50 and 100 μg Se/kg body weight/day) and CS-SeNPs (50 μg Se/kg body weight/day) could reduce atherosclerotic lesions in ApoE-/- mice after oral administration for 12 weeks. And these effects might mainly attributed to the ability of BSA-SeNPs and CS-SeNPs to inhibit hyperlipidemia by suppressing hepatic cholesterol and fatty acid metabolism, and alleviate oxidative stress by enhancing antioxidant activity. Moreover, the benefits of BSA-SeNPs were dose-dependent and the medium dose of BSA-SeNPs (50 μg Se/kg body weight/day) was optimal. Generally, BSA-SeNPs with mean size 38.5 nm and negative surface charge showed better anti-atherosclerotic effect than CS-SeNPs with mean size 65.8 nm and positive surface charge. These results suggested that SeNPs could significantly alleviate the formation of atherosclerosis in ApoE-/- mice, possibly by inhibiting hyperlipidemia and oxidative stress, exhibiting a potential to serve as an anti-atherosclerotic agent.

Selenomethionine: A Pink Trojan Redox Horse with Implications in Aging and Various Age-Related Diseases

Selenium is an essential trace element. Although this chalcogen forms a wide variety of compounds, there are surprisingly few small-molecule organic selenium compounds (OSeCs) in biology. Besides its more prominent relative selenocysteine (SeCys), the amino acid selenomethionine (SeMet) is one example. SeMet is synthesized in plants and some fungi and, via nutrition, finds its way into mammalian cells. In contrast to its sulfur analog methionine (Met), SeMet is extraordinarily redox active under physiological conditions and via its catalytic selenide (RSeR')/selenoxide (RSe(O)R') couple provides protection against reactive oxygen species (ROS) and other possibly harmful oxidants. In contrast to SeCys, which is incorporated via an eloquent ribosomal mechanism, SeMet can enter such biomolecules by simply replacing proteinogenic Met. Interestingly, eukaryotes, such as yeast and mammals, also metabolize SeMet to a small family of reactive selenium species (RSeS). Together, SeMet, proteins containing SeMet and metabolites of SeMet form a powerful triad of redox-active metabolites with a plethora of biological implications. In any case, SeMet and its family of natural RSeS provide plenty of opportunities for studies in the fields of nutrition, aging, health and redox biology.

Food Sources of Selenium and Its Relationship with Chronic Diseases

Selenium (Se) is an essential micronutrient for mammals, and its deficiency seriously threatens human health. A series of biofortification strategies have been developed to produce Se-enriched foods for combating Se deficiency. Although there have been some inconsistent results, extensive evidence has suggested that Se supplementation is beneficial for preventing and treating several chronic diseases. Understanding the association between Se and chronic diseases is essential for guiding clinical practice, developing effective public health policies, and ultimately counteracting health issues associated with Se deficiency. The current review will discuss the food sources of Se, biofortification strategies, metabolism and biological activities, clinical disorders and dietary reference intakes, as well as the relationship between Se and health outcomes, especially cardiovascular disease, diabetes, chronic inflammation, cancer, and fertility. Additionally, some concepts were proposed, there is a non-linear U-shaped dose-responsive relationship between Se status and health effects: subjects with a low baseline Se status can benefit from Se supplementation, while Se supplementation in populations with an adequate or high status may potentially increase the risk of some diseases. In addition, at supra-nutritional levels, methylated Se compounds exerted more promising cancer chemo-preventive efficacy in preclinical trials.

Food Chemistry of Selenium and Controversial Roles of Selenium in Affecting Blood Cholesterol Concentrations

Hypercholesterolemia, one of the major risk factors of cardiovascular diseases, is a worldwide public health problem. Nutraceuticals and phytochemicals are attracting attention as a result of their cholesterol-lowering ability and minimal side effects. Among them, selenium (Se) is on the list. The amount of Se in foods varies by region. Se-enriched fertilizers and feeds can raise the Se content in plants and animals, while some processing methods decrease food Se content. This review summarizes recent studies on (1) the content distribution of Se in foods and factors influencing Se-enriched foods, (2) the bioavailability and metabolism of Se, and (3) the role of Se in affecting blood cholesterol and cholesterol metabolism. Although the hypocholesterolemic effect of Se is equivocal, its cholesterol-lowering activity may be more remarkable when the Se supplementation is 200 μg/day or the baseline blood total cholesterol is above 200 mg/dL in humans with low Se status.

Rare Case of Selenite Poisoning Manifesting as Non-ST-Segment Elevation Myocardial Infarction

A female patient presented with typical angina, as well as dizziness, trembling, and repeated vomiting, after accidental poisoning with sodium selenite. Our case illustrates the role of selenite in myocardial function and provides guidance for cardiovascular management of rare cases of selenite poisoning. (Level of Difficulty: Beginner.).

Light-To-Moderate Raw Garlic Consumption Frequency Is Inversely Associated With Thickened Carotid Intima-Media Thickness: A Population-Based Study

Background: Previous animal and clinical studies have reported beneficial effects of garlic preparations on carotid intima-media thickness (cIMT). However, no epidemiological study has yet investigated the association between dietary raw garlic consumption and cIMT in the general population. The objective of this study was investigating the association between dietary raw garlic consumption and thickened cIMT in Chinese adults. Methods: This cross-sectional study used data from the Tianjin Chronic Low-grade Systemic Inflammation and Health Cohort Study. A total of 4,329 general adults from 2015 to 2017 were included in this study. Frequency of consumption of raw garlic was summarized as four categories for analysis: < 1 time/week, 1 time/week, 2-3 times/week, ≥4 times/week with a validated food frequency questionnaire. The thickened cIMT was defined as common carotid artery IMT ≥ 1.0 mm or a carotid bifurcation IMT ≥ 1.2 mm by ultrasonography. Multivariable logistic regression analysis was used to examine the association between frequency of raw garlic consumption and thickened cIMT. Results: The prevalence of thickened cIMT is 22.9% among these participants. The adjusted odds ratios (95% confidence intervals) associated with the different frequencies were 1.00 (reference) for < 1 time/week, 0.74 (0.59, 0.94) for 1 time/week, 0.71 (0.55, 0.92) for 2-3 times/week, and 0.94 (0.71, 1.25) for ≥ 4 times/week. Conclusions: Light-to-moderate raw garlic consumption was inversely associated with thickened cIMT, whereas greater raw garlic consumption (i.e., ≥4 times/week) was not associated with thickened cIMT. Future longitudinal studies should be conducted to test these findings.

Selenium, Zinc, Chromium, and Vanadium Levels in Serum, Hair, and Urine Samples of Obese Adults Assessed by Inductively Coupled Plasma Mass Spectrometry

The objective of this study was to investigate of selenium (Se), zinc (Zn), chromium (Cr), and vanadium (V) levels in blood serum, hair, and urine of adult obese patients. A total of 199 lean and 196 obese subjects were enrolled in the study. Serum, hair, and urinary metal and metalloid analysis were performed by inductively coupled plasma mass spectrometry at NexION 300D (PerkinElmer Inc., USA). The results established that obese subjects were characterized by 47% and 30% lower serum Cr and V levels compared with controls, respectively, whereas serum Se levels exceeded control values by 9%. In contrast, hair Cr, Se, and V content in obese subjects exceeded the control values by 51%, 21%, and 50%, respectively. In turn, hair Zn levels were found to be significantly lower by 11% compared with the lean control values. In urine, the levels of V and Zn were found to be 30% and 18% higher in obese patients. Prevalence of hypertension in obese subjects was associated with a trend for impaired Se and Zn levels. In a regression model adjusted for age, gender, hypertension, atherosclerosis, and glucose intolerance, serum Cr, V, and hair Zn were inversely associated with body mass index (BMI), whereas hair Se was considered as the positive predictor. Our data allow proposing that the observed alterations may at least partially contribute to metabolic disturbances in obesity. In turn, monitoring of Se exposure in a well-nourished adult population is required to reduce its potential contribution to obesity.

The importance of selenium and zinc deficiency in cardiovascular disorders

Cardiovascular diseases often linked with lifestyle are among the main causes of death, especially in the elderly population. The role of trace elements in health and disease has been emphasized in multiple scientific research. Moreover, supplementation of trace elements to improve health is becoming increasingly popular. The following paper presents current views on the relationship between the concentration of trace elements such as selenium and zinc in the body, as well as morphology and function of the cardiovascular system. Research discussing the effect of selenium and zinc supplementation on the function of the heart and blood vessels was also reviewed. The relationship between selenium and zinc concentration and morphology and function of the cardiovascular system is equally unclear, and therefore there is currently no scientific evidence for its supplementation for preventing cardiovascular diseases. It seems justified to continue scientific research on this subject due to the small number of experimental studies available on the topic of selenium and zinc deficiency and their impact on the cardiovascular system.

Modulation of hypochlorous acid (HOCl) induced damage to vascular smooth muscle cells by thiocyanate and selenium analogues

The production of hypochlorous acid (HOCl) by myeloperoxidase (MPO) plays a key role in immune defense, but also induces host tissue damage, particularly in chronic inflammatory pathologies, including atherosclerosis. This has sparked interest in the development of therapeutic approaches that decrease HOCl formation during chronic inflammation, including the use of alternative MPO substrates. Thiocyanate (SCN⁻) supplementation decreases HOCl production by favouring formation of hypothiocyanous acid (HOSCN), which is more selectively toxic to bacterial cells. Selenium-containing compounds are also attractive therapeutic agents as they react rapidly with HOCl and can be catalytically recycled. In this study, we examined the ability of SCN⁻, selenocyanate (SeCN⁻) and selenomethionine (SeMet) to modulate HOCl-induced damage to human coronary artery smooth muscle cells (HCASMC), which are critical to both normal vessel function and lesion formation in atherosclerosis. Addition of SCN⁻ prevented HOCl-induced cell death, altered the pattern and extent of intracellular thiol oxidation, and decreased perturbations to calcium homeostasis and pro-inflammatory signaling. Protection was also observed with SeCN⁻ and SeMet, though SeMet was less effective than SeCN⁻ and SCN⁻. Amelioration of damage was detected with sub-stoichiometric ratios of the added compound to HOCl. The effects of SCN⁻ are consistent with conversion of HOCl to HOSCN. Whilst SeCN⁻ prevented HOCl-induced damage to a similar extent to SCN⁻, the resulting product hyposelenocyanous acid (HOSeCN), was more toxic to HCASMC than HOSCN. These results provide support for the use of SCN⁻ and/or selenium analogues as scavengers, to decrease HOCl-induced cellular damage and HOCl production at inflammatory sites in atherosclerosis and other pathologies.

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HOCl induces extensive smooth muscle cell death and irreversible thiol oxidation.

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Addition of SCN⁻ decreases the extent of HOCl-induced cell damage.

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SeCN⁻ has similar protective effects to SCN⁻ towards HOCl-induced cell damage.

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HOSeCN is less toxic than HOCl but more damaging than HOSCN.

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SeMet modulates HOCl-induced damage but less effectively than SCN⁻ or SeCN⁻.

Oxidative Stress in Ischemic Heart Disease

One of the novel interesting topics in the study of cardiovascular disease is the role of the oxidation system, since inflammation and oxidative stress are known to lead to cardiovascular diseases, their progression and complications. During decades of research, many complex interactions between agents of oxidative stress, oxidation, and antioxidant systems have been elucidated, and numerous important pathophysiological links to na number of disorders and diseases have been established. This review article will present the most relevant knowledge linking oxidative stress to vascular dysfunction and disease. The review will focus on the role of oxidative stress in endotheleial dysfunction, atherosclerosis, and other pathogenetic processes and mechanisms that contribute to the development of ischemic heart disease.

Reduced levels of plasma selenium are associated with increased inflammation and cardiovascular disease in an Italian elderly population

Selenium (Se) is an essential micronutrient for human health that protects from oxidative damage. Se deficiency has been associated with the development of cardiovascular diseases (CVD). In this study we aimed to investigate the association between Se status, CVD risk, cardio-metabolic and inflammatory markers in elderly population. Se Plasma levels and inflammatory markers [neutrophil/lymphocyte ratio, serum C-reactive protein (CRP) levels and Copper/Zinc ratio (Cu/Zn)] were measured in 858 control subjects (mean age 73.4 ± 9.3) and 606 CVD patients (mean age 72.5± 8.7). A multivariate logistic regression was performed to evaluate the association between Se deficiency (Se< 60 μg/L) and the risk of CDV. In a subgroup of 46 CVD patients the gene expression of IL-1β, CCL5/RANTES, IL-6, IL-8, IL-10, platelet-derived growth factor-β (PDGFβ) and sirtuins in peripheral blood mononuclear cell (PBMC) were further examined. Increased values of neutrophil/lymphocyte ratio, CRP levels and Cu/Zn ratio were observed in Se deficiency condition both in controls and in CVD patients. Moreover, enhanced gene expression of cytokines and chemokines such as IL1β, CCL5 and PDGF- β, and a downregulation of SIRT-1, SIRT-5, SIRT-6, SIRT-7 were found in PBMCs from CVD patients with Se deficiency. A multivariate logistic regression showed that Se deficiency was associated with an increased CVD risk (odds ratio=1.946, 95% CI: 1.19-3.18, p < 0.01). The current study revealed that Se deficiency is independently associated with CVD, and with elevated circulating inflammatory markers and affects the expression of cytokines, chemokines and sirtuins in PBMCs.

Amorphous nano-selenium quantum dots prevent pulmonary arterial hypertension through recoupling endothelial nitric oxide synthase

AIMS

We have previously reported that nano-selenium quantum dots (SeQDs) prevented endothelial dysfunction in atherosclerosis. This study is to investigate whether amorphous SeQDs (A-SeQDs) increase endogenous tetrahydrobiopterin biosynthesis to alleviate pulmonary arterial hypertension.

RESULTS

Both A-SeQDs and C-SeQDs were stable under physiological conditions, while the size of A-SeQDs was smaller than C-SeQDs by high resolution-transmission electron microscopy scanning. In monocrotaline-injected mice, oral administration of A-SeQDs was more effective to decrease pulmonary arterial pressure, compared to C-SeQDs and organic selenium. Further, A-SeQDs increased both nitric oxide productions and intracellular BH4 levels, upregulated dihydrofolate reductase activity in lungs, and improved pulmonary arterial remodeling. Gene deletion of dihydrofolate reductase abolished these effects produced by A-SeQDs in mice. Finally, the blood levels of tetrahydrobiopterin and selenium were decreased in patients with pulmonary arterial hypertension.

CONCLUSION

A-SeQDs increase intracellular tetrahydrobiopterin to prevent pulmonary arterial hypertension through recoupling endothelial nitric oxide synthase.

METHODS

Two polymorphs of SeQDs and A-SeQDs, and a crystalline form of SeQDs (C-SeQDs) were prepared through self-redox decomposition of selenosulfate precursor. Mice were injected with monocrotaline to induce pulmonary arterial hypertension in vivo. Pulmonary arterial pressure was measured.

The Relevance of Selenium Status in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune and inflammatory disease that can cause joint damage. Among the environmental risk factors, diet plays an important role because it can aggravate or attenuate inflammation. Selenium (Se) is considered an essential trace element since it is a structural component of antioxidant enzymes; however, its concentration can be affected by diet, drugs and genetic polymorphisms. Studies have reported that RA patients have a deficient diet in some food groups that is associated with parameters of disease activity. Furthermore, it has been shown that there is an alteration in serum Se levels in this population. Although some clinical trials have been conducted in the past to analyze the effect of Se supplementation in RA, no significant results were obtained. Contrastingly, experimental studies that have evaluated the effect of novel Se nanoparticles in RA-induced models have shown promising results on the restoration of antioxidant enzyme levels. In particular, glutathione peroxidase (GPx) is an important selenoprotein that could have a modulating effect on inflammation in RA. Considering that RA patients present an inflammatory and oxidative state, the aim of this review is to give an overview of the current knowledge about the relevance of Se status in RA.

Whole transcriptome in silico screening implicates cardiovascular and infectious disease in the mechanism of action underlying atypical antipsychotic side effects

BACKGROUND

Stroke/thromboembolic events, infections, and death are all significantly increased by antipsychotics in dementia but little is known about why they can be harmful. Using a novel application of a drug repurposing paradigm, we aimed to identify potential mechanisms underlying adverse events.

METHODS

Whole transcriptome signatures were generated for SH-SY5Y cells treated with amisulpride, risperidone, and volinanserin using RNA sequencing. Bioinformatic analysis was performed that scored the association between antipsychotic signatures and expression data from 415,252 samples in the National Center for Biotechnology Information Gene Expression Omnibus (NCBI GEO) repository.

RESULTS

Atherosclerosis, venous thromboembolism, and influenza NCBI GEO-derived samples scored positively against antipsychotic signatures. Pathways enriched in antipsychotic signatures were linked to the cardiovascular and immune systems (eg, brain derived neurotrophic factor [BDNF], platelet derived growth factor receptor [PDGFR]-beta, tumor necrosis factor [TNF], transforming growth factor [TGF]-beta, selenoamino acid metabolism, and influenza infection).

CONCLUSIONS

These findings for the first time mechanistically link antipsychotics to specific cardiovascular and infectious diseases which are known side effects of their use in dementia, providing new information to explain related adverse events.

Prooxidation and Cytotoxicity of Selenium Nanoparticles at Nonlethal Level in Sprague-Dawley Rats and Buffalo Rat Liver Cells

The effects of selenium nanoparticles (SeNPs) on the antioxidant capacity in Sprague-Dawley (SD) rats were investigated. The rats were given intragastric administration of an SeNP suspension at doses of 0, 2, 4, and 8 mg Se/kg BW for two weeks. The antioxidant capacity in serum and organic tissues (liver, heart, and kidney) and the gene expression levels of glutathione peroxidase 1 (GPX1) and glutathione peroxidase 4 (GPX4) in the liver were measured. Buffalo rat liver (BRL) cell lines were further constructed to explore the cytotoxicity mechanism induced by SeNPs through the determination of antioxidant capacity; cell activity; apoptosis; and Caspase-3, Caspase-8, and Caspase-9 family activities. The results showed that SeNP administration over 4.0 mg Se/kg BW decreased the antioxidant capacities in the serum, liver, and heart and downregulated mRNA expression of GPX1 and GPX4 in the liver. The BRL cell line experiments showed that treatment with over 24 μM SeNPs decreased the viability of the cells and damaged the antioxidant capacity. Flow cytometry analysis showed that decreased cell viability induced by SeNPs is mainly due to apoptosis, rather than cell necrosis. Caspase-3 and Caspase-8 activities were also increased when BRL cells were treated with 24 μM and 48 μM SeNPs. Taken together, a nonlethal level of SeNPs could impair the antioxidant capacity in serum and organic tissues of rats, and the liver is the most sensitive to the toxicity of SeNPs. A pharmacological dose of SeNPs could lead to cytotoxicity and induce cell death through apoptosis and extrinsic pathways contributing to SeNP-induced apoptosis in BRL cells.

Vitamin E and Selenium Reduce Prednisolone Side Effects in Rat Hearts

Aim of this work was to determine the effects of dietary intake vitamin E and Se on lipid peroxidation (LPO) as Thiobarbituric acid reactive substances (TBARS) and on the antioxidative defense mechanisms in heart tissues of rats treated with high doses of prednisolone. 250 adult male Wistar rats were randomly divided into 5 groups and fed with normal diet. Additionally groups 3, 4, and 5 received a daily supplement in their drinking water of 20 mg vitamin E, 0.3 mg Se, and a combination of vitamin E and Se (20 mg/ 0.3 mg), respectively, for 30 days. For 3 d subsequently, control group was treated with placebo, and remaining four groups were injected intramuscularly with 100 mg/kg prednisolone. After last administration of prednisolone, 10 rats from each group were killed at 4, 8, 12, 24, and 48 h and the activities of antioxidant enzymes and the levels of GSH and TBARS were measured. GSH-Px, CAT activities and GSH levels decreased starting from 4th hour to 48% and 65% of control levels by 24th hour, respectively and it reincreased to control levels at 48th hour in the prednisolone group (p < 0.001, p < 0.001). In addition, prednisolone administration led 2-fold increase in heart TBARS levels at 24th hour (p < 0.001). E vitamins and Se inhibited the increase in heart TBARS and the decrease in antioxidative enzymes levels. Therefore, It is concluded that vitamin E and Se may have a preventive role in decreasing the increase of TBARS caused by prednisolone administration in our study.

Oxidative Stress and Antioxidants in Atherosclerosis Development and Treatment

Atherosclerosis can be regarded as chronic inflammatory disease affecting the arterial wall. Despite the recent progress in studying the pathogenesis of atherosclerosis, some of the pathogenic mechanisms remain to be fully understood. Among these mechanisms is oxidative stress, which is closely linked to foam cells formation and other key events in atherosclerosis development. Two groups of enzymes are involved in the emergence of oxidative stress: Pro-oxidant (including NADPH oxidases, xanthine oxidases, and endothelial nitric oxide synthase) and antioxidant (such as superoxide dismutase, catalases, and thioredoxins). Pro-oxidant enzymes in normal conditions produce moderate concentrations of reactive oxidant species that play an important role in cell functioning and can be fully utilized by antioxidant enzymes. Under pathological conditions, activities of both pro-oxidant and antioxidant enzymes can be modified by numerous factors that can be relevant for developing novel therapies. Recent studies have explored potential therapeutic properties of antioxidant molecules that are capable to eliminate oxidative damage. However, the results of these studies remain controversial. Other perspective approach is to inhibit the activity of pro-oxidant enzymes and thus to slow down the progression of atherosclerosis. In this review we summarized the current knowledge on oxidative stress in atherosclerosis and potential antioxidant approaches. We discuss several important antioxidant molecules of plant origin that appear to be promising for treatment of atherosclerosis.

Potential Role of Selenium Against Hepatotoxicity Induced by 2,4-Dichlorophenoxyacetic Acid in Albino Wistar Rats

The present study aims to investigate the hepatoprotective effects of selenium on toxicity induced by 'Désormone Lourd' based on 2,4-dichlorophenoxyacetic acid in Wistar rats. Male Wistar rats were divided into four groups and were treated orally. The (C) group was used as a control, while the test groups were treated with Se (0.2 mg/kg b.w.), 2,4-D (5 mg/kg b.w.) or both (2,4-D + Se) for 4 weeks. Our results showed that chronic treatment with 2,4-D resulted in hepatotoxicity, as revealed by an increase in liver function markers Aminotransferases (ALT, AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and total bilirubin (TB), along with reduced total protein content and albumin. An overall pro-oxidant effect was associated with a decrease in the reduced glutathione (GSH) content and the enzymatic activity of glutathione-S-transferase (GST), catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx), and an increase in malondialdehyde (MDA) and protein carbonyl levels (PCO). Microscopic observation of liver in 2,4-D-treated rats reveals lesions, which results in perivascular inflammatory infiltration around the vessel, sinusoidal dilatation and vacuolization of hepatocytes. However, selenium supplementation in 2,4-D-treated rats elicited a reduction in the toxic effects of the pesticide by improving the studied parameters, which was confirmed by the histological study of the liver. Selenium appears to have a promising prophylactic effect through its effective anti-radical action against the hepatotoxic effects of 2,4-D.

Association of circulating selenium concentration with dyslipidemia: Results from the NHANES

BACKGROUND

Observational studies have suggested that selenium levels might associate with the risk of cardio-metabolic diseases, but how circulating selenium is related to dyslipidemia remains inconclusive.

OBJECTIVES

To investigate the association of circulating selenium levels with lipid profiles and dyslipidemia among US adults.

METHODS

Using the data collected from the National Health and Nutrition Examination Survey (NHANES 1999-2006), we performed multivariate logistic regression to examine the association of circulating selenium levels (in quartiles) with total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), non-HDL-C, and atherogenic index (AI).

RESULTS

We included 2903 adults (49.3 % male) (average age: 61.9) for analysis. Circulating selenium had non-linear association with TC, LDL-C, HDL-C, and AI (all p < 0.05). When comparing with the lowest quartile, subjects with the highest quartile of circulating selenium (>147.00 μg/L) had the higher odds of elevated TG (OR: 1.75, 95% CI = 1.14, 2.68), TC (OR: 2.47, 95% CI = 1.62, 3.76), LDL-C (OR: 2.52, 95% CI = 1.60, 3.96), non-HDL-C (OR: 2.17, 95% CI = 1.41, 3.33), AI (OR: 1.20, 95% CI = 0.73, 1.97) and low-HDL-C (OR: 2.10, 95% CI = 1.19, 3.72). Similar patterns were observed in subgroup analysis.

CONCLUSIONS

Higher circulating selenium levels had non-linear association with lipid profiles and the increased odds of dyslipidemia.

Potassium selenocyanoacetate reduces the blood triacylglycerol and atherosclerotic plaques in high-fat-dieted mice

Background

Controlling blood lipid levels at the early stage of cardiovascular disease is a major focus of global disease prevention studies on atherosclerosis. The aim of our study was to investigate the effects of potassium selencyanoacetate on the blood lipid profiles and the formation of atherosclerotic plaques in mice fed with a high-fat diet.

Methods

Forty ApoE^-/- male mice aged 8-10 weeks were randomly divided into the treatment group (n=20) and control group (n=20). The mice in the treatment group were given the high-fat diet supplemented with potassium selencyanoacetate (4.63 mg/kg/day) through a gavage, whereas the control group were fed with a same high-fat diet with 1.5 mL of normal saline only. After 16 weeks, the mice were euthanized using inhalation anesthetic methods. The aortas were isolated and stained with oil red O to observe the formation of plaques. Blood samples were collected from each animal to examine the levels of total cholesterol (TC), triacylglycerol (TG), HDL cholesterol (HDL-Ch), LDL cholesterol (LDL-Ch), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and plasma urea.

Results

The percentage of the atherosclerotic plaques area was significantly lower in the treatment group than the control group (P=0.017). The levels of TG, ALT, AST, and plasma urea were significantly lower in the treatment group than the control group (all P<0.05). However, the levels of TC, HDL-Ch, and LDL-Ch were not significantly different between two groups (all P>0.05).

Conclusions

Potassium selencyanoacetate could safely reduce the TG level and high-fat-diet induced atherosclerotic plaques in mice, which could be used as a potential drug to prevent cardiovascular atherosclerotic diseases.

Selenomethionine supplementation reduces lesion burden, improves vessel function and modulates the inflammatory response within the setting of atherosclerosis

Atherosclerosis is a chronic inflammatory disease of the vasculature characterised by the infiltration of activated neutrophils and macrophages at sites of damage within the vessel wall, which contributes to lesion formation and plaque progression. Selenomethionine (SeMet) is an organic form of selenium (Se), an essential trace element that functions in the regulation of the immune response by both bolstering the endogenous thioredoxin and glutathione antioxidant defence systems and by directly scavenging damaging oxidant species. This study evaluated the effect of dietary SeMet supplementation within a high fat diet fed apolipoprotein E deficient (ApoE^−/-) mouse model of atherosclerosis. Dietary supplementation with SeMet (2 mg/kg) increased the tissue concentration of Se, and the expression and activity of glutathione peroxidase, compared to non-supplemented controls. Supplementation with SeMet significantly reduced atherosclerotic plaque formation in mouse aortae, resulted in a more stable lesion phenotype and improved vessel function. Concurrent with these results, SeMet supplementation decreased lesion accumulation of M1 inflammatory type macrophages, and decreased the extent of extracellular trap release from phorbol myristate acetate (PMA)-stimulated mouse bone marrow-derived cells. Importantly, these latter results were replicated within ex-vivo experiments on cultured neutrophils isolated from acute coronary syndrome patients, indicating the ability of SeMet to alter the acute inflammatory response within a clinically-relevant setting. Together, these data highlight the potential beneficial effect of SeMet supplementation as a therapeutic strategy for atherosclerosis.

Sodium Selenate Ameliorates Cardiac Injury Developed from High-Fat Diet in Mice through Regulation of Autophagy Activity

Obesity is often accompanied by dyslipidemia, high blood glucose, hypertension, atherosclerosis, and myocardial dysfunction. Selenate is a vital antioxidant in the cardiovascular system. The beneficial effects of selenate on obesity-associated cardiac dysfunction and potential molecular mechanism were identified in both H9C2 cells and C57BL/6J mice hearts. The cardiac histological preformation in C57BL/6J mice were evaluated by cross-sectional area (CSA) of cardiomyocytes and percent area of fibrosis in the left ventricles. The cardiac autophagy flux in H9C2 cells and C57BL/6J mice hearts was analyzed by Western blots and the number of autophagosomes and autolysosome in H9C2 cells. In the present study, we found that lipid overload caused increases in serum lipid, CSA, and percent area of fibrosis. We further found that lipid-induced accumulation of autophagosomes  was due to depressed autophagy degradation, which was not restored in the pretreatment with 3-methyladenine and chloroquine, whereas, it was improved by rapamycin. Moreover, we demonstrated that increased levels of serum lipid, CSA, percent area of fibrosis and mRNA expression related to cardiomyocytes hypertrophy and fibrosis were significantly reduced after selenate treatments of mice. We also found selenate treatment significantly down-regulated activity of the Akt pathway, which was activated in response to lipid-overload. Furthermore, selenate dramatically improved cardiac autophagic degradation which was suppressed after exposure to lipid-overload in both H9C2 cells and C57BL/6J mice hearts. Taken together, selenate offers therapeutic intervention in lipid-related metabolic disorders, and protection against cardiac remodeling, likely through regulation of the activity of autophagic degradation and Akt pathway.

Selenium nanoparticles alleviate hyperlipidemia and vascular injury in ApoE-deficient mice by regulating cholesterol metabolism and reducing oxidative stress

Atherosclerosis and related cardiovascular diseases represent the greatest threats to human health worldwide. This study was designed to investigate the anti-atherosclerotic activity of selenium nanoparticles (SeNPs) in apolipoprotein E deficient (ApoE^-/-) mice fed a high-cholesterol, high-fat diet. The results demonstrated that animals either treated with SeNPs (50 μg Se per kg per day) or with atorvastatin (10 mg per kg per day) alone showed significant relief of vascular injury after 8 weeks of treatment. SeNPs could obviously decrease the level of serum total cholesterol, triglyceride and low-density lipoprotein cholesterol, whereas increase serum high-density lipoprotein cholesterol. At the same time, SeNPs regulated the expression levels of key genes associated with cholesterol metabolism in the liver. Furthermore, SeNPs significantly reduced the lipid peroxidation level, but increased the NO level and the activities of glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase in the serum and liver. SeNPs also increased the expression levels of antioxidant selenoenzymes or selenoproteins in the liver. In addition, SeNPs could alleviate H₂O₂-induced cytotoxicity and oxidative stress by upregulating the activities of SOD and GPx in endothelial cells cultured in vitro. These results suggested that SeNPs could significantly alleviate hyperlipidemia and vascular injury in ApoE^-/- mice, possibly by regulating cholesterol metabolism and reducing oxidative stress through antioxidant selenoenzymes/selenoproteins. SeNPs might be a potential candidate for the prevention of atherosclerosis.

Selenoprotein-P Deficiency Predicts Cardiovascular Disease and Death

Selenoprotein-P (SELENOP) is the main carrier of selenium to target organs and reduces tissue oxidative stress both directly and by delivering selenium to protective selenoproteins. We tested if the plasma concentration of SELENOP predicts cardiovascular morbidity and mortality in the primary preventive setting. SELENOP was measured from the baseline exam in 2002–2006 of the Malmö Preventive Project, a population-based prospective cohort study, using a validated ELISA. Quintiles of SELENOP concentration were related to the risk of all-cause mortality, cardiovascular mortality, and a first cardiovascular event in 4366 subjects during a median (interquartile range) follow-up time of 9.3 (8.3–11) years using Cox proportional Hazards Model adjusting for cardiovascular risk factors. Compared to subjects in the lowest quintile of SELENOP, the risk of all three endpoints was significantly lower in quintiles 2–5. The risk (multivariate adjusted hazard ratio, 95% CI) decreased gradually with the lowest risk in quintile 4 for all-cause mortality (0.57, 0.48–0.69) (p < 0.001), cardiovascular mortality (0.52, 0.37–0.72) (p < 0.001), and first cardiovascular event (0.56, 0.44–0.71) (p < 0.001). The lower risk of a first cardiovascular event in quintiles 2–5 as compared to quintile 1 was significant for both coronary artery disease and stroke. We conclude that the 20% with lowest SELENOP concentrations in a North European population without history of cardiovascular disease have markedly increased risk of cardiovascular morbidity and mortality, and preventive selenium supplementation studies stratified for these subjects are warranted.

High-quality Al@Fe-MOF prepared using Fe-MOF as a micro-reactor to improve adsorption performance for selenite

High-quality Al@Fe-MOF was prepared by in situ modification of Fe-MOF with Al³⁺ to improve the adsorption performance for selenite (Se(Ⅳ)). The structures and properties of Al@Fe-MOF were characterized by powder X-ray diffraction, high resolution transmission electron microscope, X-ray photoelectron spectroscopy (XPS), nitrogen isothermal adsorption-desorption measurement and zeta potential. The adsorption performance of Al@Fe-MOF for Se(Ⅳ) was studied by batch adsorption experiments. A large number of pores in Al@Fe-MOF were filled by AlOOH and some bayerite formed on the surfaces. Compared with those of Fe-MOF, the specific surface area (SSA) and microporosity of Al@Fe-MOF decreased to 1368 m²/g and 38.5%, respectively. Hydrolysis occurred at pH > 5.0 for Fe-MOF, but did not for Al@Fe-MOF at the pH range of 3.0-7.0. Compared with in Fe-MOF, the adsorption capacity and efficiency of SSA for Se(Ⅳ) were increased by 77% and 112%, and the average free energy of adsorption was increased to 11.62 kJ/mol in Al@Fe-MOF. Besides, the Se(Ⅳ) adsorption amount of Al@Fe-MOF was almost not influenced by the pH from 3.0 to 7.0. The high resolution XPS (HR-XPS) and pH analysis indicated that Al species in Al@Fe-MOF could significantly increase the density of adsorption sites to improve its adsorption capacity for Se(Ⅳ).

Amorphous nano-selenium quantum dots improve endothelial dysfunction in rats and prevent atherosclerosis in mice through Na+/H+ exchanger 1 inhibition

AIM

Selenium, a trace element involved in important enzymatic activities inside the body, has protective effects against cardiovascular diseases including atherosclerosis. The safe dose of selenium in the organism is very narrow, limiting the supplementation of selenium in diet. The aim of this study is to explore whether selenium quantum dots (SeQDs) prevent atherosclerosis and to investigate the potential mechanisms.

METHODS

An amorphous form of SeQDs (A-SeQDs) and a crystalline form of SeQDs (C-SeQDs) were prepared through self-redox decomposition of selenosulfate precursor. Endothelial dysfunction was induced by balloon injury plus high fat diet (HFD) in rats. Atherosclerotic model was established by feeding Apoe^-/- mice with HFD.

RESULTS

Administrations of A-SeQDs but not C-SeQDs dramatically improved endothelium-dependent relaxation, and accelerated would healing in primary endothelial cells isolated from rats, which was comprised by co-treatment of LiCl. Lentivirus-mediated knockdown of Na⁺/H⁺ exchanger 1 (NHE1) abolished LiCl-induced endothelial dysfunction in rats. In cultured endothelial cells, A-SeQDs, as well as cariporide, inhibited NHE1 activities, decreased intracellular pH value and Ca²⁺ concentration, and reduced calpain activity increased by ox-LDL. These protective effects of A-SeQDs were reversed by LiCl treatment in endothelial cells. In Apoe^-/- mice feeding with HFD, A-SeQDs prevented endothelial dysfunction and reduced the size of atherosclerotic plaque in aortic arteries. Further, lentivirus-mediated NHE1 gene overexpression abolished the protective effects of A-SeQDs against endothelial dysfunction and atherosclerosis in Apoe^-/- mice.

CONCLUSION

A-SeQDs prevents endothelial dysfunction and the growth of atherosclerotic plaque through NHE1 inhibition and subsequent inactivation of Ca²⁺/calpain signaling. Clinically, the administration of A-SeQDs is an effective approach to treat atherosclerosis.

Using SeO2 as a selenium source to make RSe-substituted aniline and imidazo[1,2-a]pyridine derivatives

A mild and practical method is developed for the synthesis of ArSe-substituted aniline and imidazo[1,2-a]pyridine derivatives using SeO₂ as a selenium agent.

The role of the thioredoxin/thioredoxin reductase system in the metabolic syndrome: towards a possible prognostic marker?

Mammalian thioredoxin reductase (TrxR) is a selenoprotein with three existing isoenzymes (TrxR1, TrxR2, and TrxR3), which is found primarily intracellularly but also in extracellular fluids. The main substrate thioredoxin (Trx) is similarly found (as Trx1 and Trx2) in various intracellular compartments, in blood plasma, and is the cell's major disulfide reductase. Thioredoxin reductase is necessary as a NADPH-dependent reducing agent in biochemical reactions involving Trx. Genetic and environmental factors like selenium status influence the activity of TrxR. Research shows that the Trx/TrxR system plays a significant role in the physiology of the adipose tissue, in carbohydrate metabolism, insulin production and sensitivity, blood pressure regulation, inflammation, chemotactic activity of macrophages, and atherogenesis. Based on recent research, it has been reported that the modulation of the Trx/TrxR system may be considered as a new target in the management of the metabolic syndrome, insulin resistance, and type 2 diabetes, as well as in the treatment of hypertension and atherosclerosis. In this review evidence about a possible role of this system as a marker of the metabolic syndrome is reported.

Long-Term Excessive Selenium Supplementation Induces Hypertension in Rats

Selenium (Se) is an essential trace element involved in several biological pathways, naturally found in rocks, soils, and food. Even though the daily requirement of Se is achieved through a balanced diet, the use of Se supplements has been frequent. Due to the risk of toxic effects of having Se in excess, supplementation is still under debate. The aim was to evaluate the effects of long-term Se supplementation upon systolic blood pressure (SBP) and redox status of rats exposed to sodium selenite. Male Wistar rats were exposed to 2 and 6 mg/L of sodium selenite in drinking water for 85 days. SBP and body weight were evaluated weekly; oxidative stress biomarkers were measured in blood or plasma; and Se levels were assessed in blood, plasma, kidney, and liver. Se supplementation (2 and 6 mg/L) induced significant increase in the SBP in rats from the 42nd day until the end of the study. This increase on SBP was not associated with significant changes in oxidative stress biomarkers. A significant increase in Se levels was found in whole blood, kidney, and liver from both groups of rats receiving Se supplementation when compared to control. Although the exact mechanisms underlying this augment in SBP are not clear, they are potentially related to other Se biological routes besides the synthesis of selenoproteins, such as GSH-Px. Due to the negative effects upon blood pressure, precautionary measures are advised, since the selling of supplements does not require a medical prescription.

Selenium Concentrations and Mortality among Community-Dwelling Older Adults: Results from IlSIRENTE Study

BACKGROUND

Selenium has a wide range of pleiotropic effects, influencing redox homeostasis, thyroid hormone metabolism, and protecting from oxidative stress and inflammation. Serum selenium levels are reduced in the older population.

OBJECTIVES

to investigate the association of serum selenium levels with all-cause mortality in a sample of community-dwelling older adults.

DESIGN AND SETTING

Data are from the 'Invecchiamento e Longevità nel Sirente' (Aging and Longevity in the Sirente geographic area, ilSIRENTE) study, a prospective cohort study that collected information on individuals aged 80 years and older living in an Italian mountain community (n=347). The main outcome was risk of death after ten years of follow-up.

PARTICIPANTS AND MEASUREMENTS

Participants were classified according to the median value of selenium (105.3 μg/L) in two groups: high selenium and low selenium.

RESULTS

A total of 248 deaths occurred during a 10-year follow-up. In the unadjusted model, low levels of selenium was associated with increased mortality (HR, 0.66; 95% CI 0.51-0.85). After adjusting for potential confounders the relationship remained significant (HR, 0.71; 95% CI 0.54-0.92).

CONCLUSIONS

Low serum levels of selenium are associated with reduced survival in elderly, independently of age and other clinical and functional variables.

Trace minerals intake: Risks and benefits for cardiovascular health

Minerals play a major role in regulating cardiovascular function. Imbalances in electrolyte minerals are frequent and potentially hazardous occurrences that may lead to the development of cardiovascular diseases (CVDs). Transition metals, such as iron, zinc, copper and selenium, play a major role in cell metabolism. However, there is controversy over the effects of dietary and supplemental intake of these metals on cardiovascular risk factors and events. Since their pro-oxidant or antioxidant functions can have different effects on cardiovascular health. While deficiency of these trace elements can cause cardiovascular dysfunction, several studies have also shown a positive association between metal serum levels and cardiovascular risk factors and events. Thus, a J- or U-shaped relationship between the transition minerals and cardiovascular events has been proposed. Given the existing controversies, large, well-designed, long-term, randomized clinical trials are required to better examine the effects of trace mineral intake on cardiovascular events and all-cause mortality in the general population. In this review, we discuss the role of dietary and/or supplemental iron, copper, zinc, and selenium on cardiovascular health. We will also clarify their clinical applications, benefits, and harms in CVDs prevention.

Organoselenium compounds as mimics of selenoproteins and thiol modifier agents

Selenium is an essential trace element for animals and its role in the chemistry of life relies on a unique functional group: the selenol (-SeH) group. The selenol group participates in critical redox reactions. The antioxidant enzymes glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) exemplify important selenoproteins. The selenol group shares several chemical properties with the thiol group (-SH), but it is much more reactive than the sulfur analogue. The substitution of S by Se has been exploited in organic synthesis for a long time, but in the last 4 decades the re-discovery of ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one) and the demonstration that it has antioxidant and therapeutic properties has renovated interest in the field. The ability of ebselen to mimic the reaction catalyzed by GPx has been viewed as the most important molecular mechanism of action of this class of compound. The term GPx-like or thiol peroxidase-like reaction was previously coined in the field and it is now accepted as the most important chemical attribute of organoselenium compounds. Here, we will critically review the literature on the capacity of organoselenium compounds to mimic selenoproteins (particularly GPx) and discuss some of the bottlenecks in the field. Although the GPx-like activity of organoselenium compounds contributes to their pharmacological effects, the superestimation of the GPx-like activity has to be questioned. The ability of these compounds to oxidize the thiol groups of proteins (the thiol modifier effects of organoselenium compounds) and to spare selenoproteins from inactivation by soft-electrophiles (MeHg⁺, Hg²⁺, Cd²⁺, etc.) might be more relevant for the explanation of their pharmacological effects than their GPx-like activity. In our view, the exploitation of the thiol modifier properties of organoselenium compounds can be harnessed more rationally than the use of low mass molecular structures to mimic the activity of high mass macromolecules that have been shaped by millions to billions of years of evolution.

Porous Se@SiO2 nanospheres treated paraquat-induced acute lung injury by resisting oxidative stress

Acute paraquat (PQ) poisoning is one of the most common forms of pesticide poisoning. Oxidative stress and inflammation are thought to be important mechanisms in PQ-induced acute lung injury (ALI). Selenium (Se) can scavenge intracellular free radicals directly or indirectly. In this study, we investigated whether porous Se@SiO₂ nanospheres could alleviate oxidative stress and inflammation in PQ-induced ALI. Male Sprague Dawley rats and RLE-6TN cells were used in this study. Rats were categorized into 3 groups: control (n=6), PQ (n=18), and PQ + Se@SiO₂ (n=18). The PQ and PQ + Se@SiO₂ groups were randomly and evenly divided into 3 sub-groups according to different time points (24, 48 and 72 h) after PQ treatment. Porous Se@SiO₂ nanospheres 1 mg/kg (in the PQ + Se@SiO₂ group) were administered via intraperitoneal injection every 24 h. Expression levels of reduced glutathione, malondialdehyde, superoxide dismutase, reactive oxygen species (ROS), nuclear factor-κB (NF-κB), phosphorylated NF-κB (p-NF-κB), tumor necrosis factor-α and interleukin-1β were detected, and a histological analysis of rat lung tissues was performed. The results showed that the levels of ROS, malondialdehyde, NF-κB, p-NF-κB, tumor necrosis factor-α and interleukin-1β were markedly increased after PQ treatment. Glutathione and superoxide dismutase levels were reduced. However, treatment with porous Se@SiO₂ nanospheres markedly alleviated PQ-induced oxidative stress and inflammation. Additionally, the results from histological examinations and wet-to-dry weight ratios of rat lung tissues showed that lung damage was reduced after porous Se@SiO₂ nanosphere treatment. These data indicate that porous Se@SiO₂ nanospheres may reduce NF-κB, p-NF-κB and inflammatory cytokine levels by inhibiting ROS in PQ-induced ALI. This study demonstrates that porous Se@SiO₂ nanospheres may be a therapeutic method for use in the future for PQ poisoning.

Lycopene restores trace element levels in ochratoxin A-treated rats

This study was designed to investigate the in vivo effects of ochratoxin A (OTA) and/or lycopene on the levels of selenium, zinc, and copper in the liver, kidneys, and testes of male Sprague-Dawley rats. The rats were treated with OTA (0.5 mg kg-1 day-1) and/or lycopene (5 mg kg-1 day-1) by gavage for 7 or 14 days. Trace element levels were measured by atomic absorption spectrometry. OTA significantly lowered selenium (20 % in the liver, 17 % in the kidney, and 40 % in the testis), zinc (24 % in the liver, 23 % in the kidney, and 26 % in the testis), and copper levels (40 % in the liver and 10 % in the kidney). Lycopene alone did not affect the trace element levels in any of the organs. In combination with OTA, however, it significantly restored liver, kidney, and testis selenium and zinc levels compared to the group treated with OTA alone. Our results have confirmed that depletion of trace elements in different organs is one of the mechanisms of action of OTA. They also suggest that lycopene interferes with this depleting effect and restores trace element levels, the implications of which need to be further investigated.