Integrated Analysis of Genomic and Genome-Wide Association Studies Identified Candidate Genes for Nutrigenetic Studies in Flavonoids and Vascular Health: Path to Precision Nutrition for (Poly)phenols

Flavonoids exert vasculoprotective effects in humans, but interindividual variability in their action has also been reported. This study aims to identify genes that are associated with vascular health effects of flavonoids and whose polymorphisms could explain interindividual variability in response to their intake. Applying the predetermined literature search criteria, we identified five human intervention studies reporting positive effects of flavonoids on vascular function together with global genomic changes analyzed using microarray methods. Genes involved in vascular dysfunction were identified from genome-wide association studies (GWAS). By extracting data from the eligible human intervention studies, we obtained 5807 differentially expressed genes (DEGs). The number of identified upstream regulators (URs) varied across the studies, from 227 to 1407. The search of the GWAS Catalog revealed 493 genes associated with vascular dysfunction. An integrative analysis of transcriptomic data with GWAS genes identified 106 candidate DEGs and 42 candidate URs, while subsequent functional analyses and a search of the literature identified 20 top priority candidate genes: ALDH2, APOE, CAPZA1, CYP11B2, GNA13, IL6, IRF5, LDLR, LPL, LSP1, MKNK1, MMP3, MTHFR, MYO6, NCR3, PPARG, SARM1, TCF20, TCF7L2, and TNF. In conclusion, this integrated analysis identifies important genes to design future nutrigenetic studies for development of precision nutrition for polyphenols.

Exploring the Relationship between Mediterranean Diet Adherence and Subjective Well-Being among Greek and Cypriot Adults

Associations between subjective well-being (SWB) and dietary habits, employment status, and habitual activities are increasingly capturing the focus of researchers as well as policymakers worldwide. This study aimed to explore these associations in a sample of the population in Greece and Cyprus via an online survey. In total, 936 questionnaires (470: Cyprus, 466: Greece) were analyzed to study the associations between the Mediterranean Diet (MD) (using the 14-item MEDAS score, (14-MEDAS)), subjective well-being (SWB), and several socioeconomic factors. Key remarks of this survey highlight the positive impact of MD adherence on some well-being items. Namely, statistically significant differences were found on the following items: Satisfied with life (p < 0.001), Life worthwhile (p < 0.001), Feeling happy (p < 0.001), worried (p = 0.005), and depressed (p = 0.001), when comparing Low MD adherence (14-MEDAS < 5) to High MD adherence (14-MEDAS > 10). Other lifestyle habits such as spending time with friends and family, spending time in nature, and habitual physical activity were associated with aspects of SWB such as Life satisfaction, Life worthwhile, Feeling happy, and energetic. The findings support adherence to the MD, since it is associated with higher life satisfaction and self-reported happiness in this sample and should be considered when developing health policies on well-being.

The Role of NAD+ in Metabolic Regulation of Adipose Tissue: Implications for Obesity-Induced Insulin Resistance

Obesity-induced insulin resistance is among the key factors in the development of type 2 diabetes, atherogenic dyslipidemia and cardiovascular disease. Adipose tissue plays a key role in the regulation of whole-body metabolism and insulin sensitivity. In obesity, adipose tissue becomes inflamed and dysfunctional, exhibiting a modified biochemical signature and adipokine secretion pattern that promotes insulin resistance in peripheral tissues. An important hallmark of dysfunctional obese adipose tissue is impaired NAD+/sirtuin signaling. In this chapter, we summarize the evidence for impairment of the NAD+/sirtuin pathway in obesity, not only in white adipose tissue but also in brown adipose tissue and during the process of beiging, together with correlative evidence from human studies. We also describe the role of PARPs and CD38 as important NAD+ consumers and discuss findings from experimental studies that investigated potential NAD+ boosting strategies and their efficacy in restoring impaired NAD+ metabolism in dysfunctional obese adipose tissue. In sum, these studies suggest a critical role of NAD+ metabolism in adipose biology and provide a basis for the potential development of strategies to restore metabolic health in obesity.

Square-wave voltammetry of human blood serum

A study on voltammetric analysis of blood serum diluted in a phosphate buffer is presented using advanced square-wave voltammetry at an edge plane pyrolytic graphite electrode. The results demonstrate that even in a complex medium like human blood serum, electrochemical characterization can be achieved through the use of advanced voltammetric techniques in conjunction with an appropriate commercially available electrode, such as the edge plane pyrolytic graphite electrode, which boosts superior electrocatalytic properties. Without undergoing any chemical treatment of the serum sample, the square-wave voltammetry technique reveals, for the first time, the electrode reactions of uric acid, bilirubin, and albumin in a single experiment, as represented by well-defined, separated, and intense voltammetric signals. All electrode processes are surface-confined, indicating that the edge plane sites of the electrode serve as an ideal platform for the competitive adsorption of electroactive species, despite the extensive chemical complexity of the serum samples. The speed and differential nature of square-wave voltammetry are crucial for obtaining an outstanding resolution of the voltammetric peaks, maintaining the quasi-reversible nature of the underlying electrode processes, while reducing the impact of follow-up chemical reactions that are coupled to the initial electron transfer for all three detected species, and minimizing fouling of the electrode surface.

Molecular mechanisms underlying hypertensive effect of fructose and the preventive properties of inulin - Global transcriptomic analysis in rat aorta

BACKGROUND AND AIMS

Excessive intake of fructose is a significant contributor in the development of hypertension and pathogenesis of cardiometabolic diseases. We previously showed that dietary inulin can prevent fructose-induced hypertension in rats. Nevertheless, molecular mechanisms of both fructose and inulin in aorta remain unknown. The aim of this study was to identify global transcriptomic changes in aorta in rats on fructose-based diet or partial substitution of dietary fructose with inulin.

METHODS AND RESULTS

At the end of study periods, aortas were isolated, RNA extracted, and transcriptomics performed using microarrays followed by in-dept bioinformatic analyses. We observed that fructose-based diet affected the expression of over 1700 genes involved in the regulation of vascular functions, cell signaling, and cellular metabolism. Partial substitution of dietary fructose with inulin affected the expression of over 1300 genes regulating endothelial and vascular functions, including relaxin signaling pathway, immune/inflammatory response, or cellular metabolism. Bioinformatic analyses revealed transcription factors, such as Junb or Nr4a2, and miRNAs, such as miR-206, miR-137 or miR-375, as potential transcriptional and post-transcriptional regulators of identified differentially expressed genes. Genes identified following both diets are associated with development of cardiovascular diseases, hypertension, immune system diseases and metabolic diseases. Moreover, a negative correlation between the expression profiles obtained by fructose-based diet and that by partial substitution of dietary fructose with inulin was observed.

CONCLUSION

Our study showed that fructose can significantly impact global transcriptomic profile in aorta, changes that can be counteracted by inulin and which present relevant molecular mechanisms underlying its anti-hypertensive property.

Multigenomic modifications in human circulating immune cells in response to consumption of polyphenol rich extract of yerba mate (Ilex paraguariensis A. St.-Hil.) are suggestive of cardiometabolic protective effects

Mate is a traditional drink obtained from the leaves of yerba mate and rich in a diversity of plant bioactive compounds including polyphenols, particularly chlorogenic acids. Studies, even though limited, suggest that consumption of mate is associated with health effects, including prevention of cardiometabolic disorders. Molecular mechanisms underlying the potential health properties are still largely unknown, especially in humans. The aim of this study was to investigate nutrigenomic effects of mate consumption and identify regulatory networks potentially mediating cardiometabolic health benefits. Healthy middle-aged men at risk for cardiovascular disease consumed a standardized mate extract or placebo for 4 weeks. Global gene expression, including protein coding and non-coding RNAs profiles were determined using microarrays. Biological function analyses were performed using integrated bioinformatic tools. Comparison of global gene expression profiles showed significant change following mate consumption with 2635 significantly differentially expressed genes, among which 6 are miRNAs and 244 are lncRNAs. Functional analyses showed that these genes are involved in regulation of cell interactions and motility, inflammation or cell signaling. Transcription factors, such as MEF2A, MYB or HNF1A, could have their activity modulated by mate consumption either by direct interaction with polyphenol metabolites or by interactions of metabolites with cell signaling proteins, like p38 or ERK1/2, that could modulate transcription factor activity and regulate expression of genes observed. Correlation analysis suggests that expression profile is inversely associated with gene expression profiles of patients with cardiometabolic disorders. Therefore, mate consumption may exert cardiometabolic protective effects by modulating gene expression towards a protective profile.

Exploring Hedonic and Eudaimonic Items of Well-Being in Mediterranean and Non-Mediterranean Countries: Influence of Sociodemographic and Lifestyle Factors

Increased understanding of subjective well-being (SWB), as well as factors that influence it, are essential to enhance well-being at the individual and national level. We have applied a hedonic and eudaimonic 9-item composed tool (SWB score) to measure SWB across several Mediterranean (MED) and non-Mediterranean (non-MED) countries, and to explore the association between the SWB score and a range of sociodemographic, health and Mediterranean lifestyle factors. A specifically designed web-based questionnaire was distributed to adult participants (N = 2400) from Spain, Italy, Portugal, Bulgaria and Republic of North Macedonia. Results showed that the SWB score was significantly different across the examined countries with the MED participants displaying slightly higher average scores than the non-MED ones (6.3 ± 1.5 vs. 6.1 ± 1.6, p = 0.002). Several sociodemographic, health status and lifestyle factors displayed a significant but limited association with the 9-item SWB score, with a multiple regression model explaining around 17% of the variance. Nevertheless, our results support that a closer adherence to Mediterranean lifestyle habits—the Mediterranean Diet, spending time with friends, family, and in nature, being active, and getting adequate rest at night—has a positive influence on the 9-item SWB score. Further research is needed to advance the understanding of the measuring and differentiating of SWB across different populations and to establish all the factors that influence it.

Polyphenols Could Prevent SARS-CoV-2 Infection by Modulating the Expression of miRNAs in the Host Cells

Coronaviruses (CoVs) are single-stranded RNA viruses which following virus attachment and entry into the host cell, particularly type 2 pneumocytes but also endothelial cells, release RNA into cytosol where it serves as a matrix for the host translation machinery to produce viral proteins. The viral RNA in cytoplasm can interact with host cell microRNAs which can degrade viral RNA and/or prevent viral replication. As such host cellular miRNAs represent key cellular mediators of antiviral defense. Polyphenols, plant food bioactives, exert antiviral properties, which is partially due to their capacity to modulate the expression of miRNAs. The objective of this work was to assess if polyphenols can play a role in prevention of SARS-CoV-2 associated complications by modulating the expression of host miRNAs. To test this hypothesis, we performed literature search to identify miRNAs that could bind SARS-CoV-2 RNA as well as miRNAs which expression can be modulated by polyphenols in lung, type 2 pneumocytes or endothelial cells. We identified over 600 miRNAs that have capacity to bind viral RNA and 125 miRNAs which expression can be modulated by polyphenols in the cells of interest. We identified that there are 17 miRNAs with both the capacity to bind viral RNA and which expression can be modulated by polyphenols. Some of these miRNAs have been identified as having antiviral properties or can target genes involved in regulation of processes of viral replication, apoptosis or viral infection. Taken together this analysis suggests that polyphenols could modulate expression of miRNAs in alveolar and endothelial cells and exert antiviral capacity.

Circadian rhythm and time-of-day-effects of (anti)oxidant biomarkers for epidemiological studies

Various biomarkers of oxidative stress and redox status have been used in a number of clinical and epidemiological studies related to diseases and conditions that involve disturbances of the redox balance. However, a comprehensive study of diurnal variations of a set of biomarkers has not been conducted so far. Therefore, the aim of this study is to investigate circadian rhythm and time-of-day-effects of a set of frequently used biomarkers of oxidative stress, redox and antioxidant status in serum/plasma. These biomarkers include Reactive Oxygen Metabolites (ROM), Biological Antioxidant Potency (BAP), Total Thiols in Proteins (TTP), high-sensitive C-Reactive Protein (CRP) and Uric Acid (UA). During a 24-hr study, blood sampling was conducted 6 times at 4-hr intervals. The presence of circadian rhythm was analyzed with CircWave analysis, whereas the effect of time was analyzed with Repeated Measures ANOVA (RM-ANOVA). Thereby, the main focus was on the time points in working hours (8, 12 and 16 hr), which are used frequently in practice. Of all investigated biomarkers, only TTP in males demonstrated statistically significant circadian rhythm (p = 0.040). A statistically significant effect between all six time points with RM-ANOVA was observed for ROM, TTP and UA in both genders, and for BAP in females only. No statistically significant differences were observed between the time points 8 hr and 12 hr for any of the biomarkers that were assessed in our study. In conclusion, diurnal variations in some of the studied biomarkers that we demonstrate here should be taken into account when designing and conducting clinical and epidemiological studies. It is advised to standardize the time of sampling with a preference in the morning hours.

Systematic Bioinformatic Analyses of Nutrigenomic Modifications by Polyphenols Associated with Cardiometabolic Health in Humans-Evidence from Targeted Nutrigenomic Studies

Cardiometabolic disorders are among the leading causes of mortality in the human population. Dietary polyphenols exert beneficial effects on cardiometabolic health in humans. Molecular mechanisms, however, are not completely understood. Aiming to conduct in-depth integrative bioinformatic analyses to elucidate molecular mechanisms underlying the protective effects of polyphenols on cardiometabolic health, we first conducted a systematic literature search to identify human intervention studies with polyphenols that demonstrate improvement of cardiometabolic risk factors in parallel with significant nutrigenomic effects. Applying the predefined inclusion criteria, we identified 58 differentially expressed genes at mRNA level and 5 miRNAs, analyzed in peripheral blood cells with RT-PCR methods. Subsequent integrative bioinformatic analyses demonstrated that polyphenols modulate genes that are mainly involved in the processes such as inflammation, lipid metabolism, and endothelial function. We also identified 37 transcription factors that are involved in the regulation of polyphenol modulated genes, including RELA/NFKB1, STAT1, JUN, or SIRT1. Integrative bioinformatic analysis of mRNA and miRNA-target pathways demonstrated several common enriched pathways that include MAPK signaling pathway, TNF signaling pathway, PI3K-Akt signaling pathway, focal adhesion, or PPAR signaling pathway. These bioinformatic analyses represent a valuable source of information for the identification of molecular mechanisms underlying the beneficial health effects of polyphenols and potential target genes for future nutrigenetic studies.

Molecular Determinants of the Cardiometabolic Improvements of Dietary Flavanols Identified by an Integrative Analysis of Nutrigenomic Data from a Systematic Review of Animal Studies

SCOPE

Flavanols are important polyphenols of the human diet with extensive demonstrations of their beneficial effects on cardiometabolic health. They contribute to preserve health acting on a large range of cellular processes. The underlying mechanisms of action of flavanols are not fully understood but involve a nutrigenomic regulation.

METHODS AND RESULTS

To further capture how the intake of dietary flavanols results in the modulation of gene expression, nutrigenomics data in response to dietary flavanols obtained from animal models of cardiometabolic diseases have been collected and submitted to a bioinformatics analysis. This systematic analysis shows that dietary flavanols modulate a large range of genes mainly involved in endocrine function, fatty acid metabolism, and inflammation. Several regulators of the gene expression have been predicted and include transcription factors, miRNAs and epigenetic factors.

CONCLUSION

This review highlights the complex and multilevel action of dietary flavanols contributing to their strong potential to preserve cardiometabolic health. The identification of the potential molecular mediators and of the flavanol metabolites driving the nutrigenomic response in the target organs is still a pending question which the answer will contribute to optimize the beneficial health effects of dietary bioactives.

Systematic bioinformatic analysis of nutrigenomic data of flavanols in cell models of cardiometabolic disease

Flavanol intake positively influences several cardiometabolic risk factors in humans. However, the specific molecular mechanisms of action of flavanols, in terms of gene regulation, in the cell types relevant to cardiometabolic disease have never been systematically addressed. On this basis, we conducted a systematic literature review and a comprehensive bioinformatic analysis of genes whose expression is affected by flavanols in cells defining cardiometabolic health: hepatocytes, adipocytes, endothelial cells, smooth muscle cells and immune cells. A systematic literature search was performed using the following pre-defined criteria: treatment with pure compounds and metabolites (no extracts) at low concentrations that are close to their plasma concentrations. Differentially expressed genes were analyzed using bioinformatics tools to identify gene ontologies, networks, cellular pathways and interactions, as well as transcriptional and post-transcriptional regulators. The systematic literature search identified 54 differentially expressed genes at the mRNA level in in vitro models of cardiometabolic disease exposed to flavanols and their metabolites. Global bioinformatic analysis revealed that these genes are predominantly involved in inflammation, leukocyte adhesion and transendothelial migration, and lipid metabolism. We observed that, although the investigated cells responded differentially to flavanol exposure, the involvement of anti-inflammatory responses is a common mechanism of flavanol action. We also identified potential transcriptional regulators of gene expression: transcriptional factors, such as GATA2, NFKB1, FOXC1 or PPARG, and post-transcriptional regulators: miRNAs, such as mir-335-5p, let-7b-5p, mir-26b-5p or mir-16-5p. In parallel, we analyzed the nutrigenomic effects of flavanols in intestinal cells and demonstrated their predominant involvement in the metabolism of circulating lipoproteins. In conclusion, the results of this systematic analysis of the nutrigenomic effects of flavanols provide a more comprehensive picture of their molecular mechanisms of action and will support the future setup of genetic studies to pave the way for individualized dietary recommendations.

Persistent Moderate-to-Weak Mediterranean Diet Adherence and Low Scoring for Plant-Based Foods across Several Southern European Countries: Are We Overlooking the Mediterranean Diet Recommendations?

The Mediterranean diet (MD) has been sponsored worldwide as a healthy and sustainable diet. Our aim was to update and compare MD adherence and food choices across several Southern European countries: Spain (SP), Portugal (PT), Italy (IT), Greece (GR), and Cyprus (CY) (MED, Mediterranean), and Bulgaria (BG) and the Republic of North Macedonia (NMK) (non-MED, non-Mediterranean). Participants (N = 3145, ≥18 y) completed a survey (MeDiWeB) with sociodemographic, anthropometric, and food questions (14-item Mediterranean Diet Adherence Screener, 14-MEDAS). The MED and non-MED populations showed moderate (7.08 ± 1.96) and weak (5.58 ± 1.82) MD adherence, respectively, with significant yet small differences across countries (SP > PT > GR > IT > CY > BG > NMK, p-value < 0.001). The MED participants scored higher than the non-MED ones for most of the Mediterranean-typical foods, with the greatest differences found for olive oil (OO) and white meat preference. In most countries, ≥70% of the participants reported quantities of red meat, butter, sweet drinks, and desserts below the recommended cutoff points, whereas <50% achieved the targets for plant-based foods, OO, fish, and wine. Being a woman and increasing age were associated with superior adherence (p-value < 0.001), but differences were rather small. Our results suggest that the campaigns carried out to support and reinforce the MD and to promote plant-based foods have limited success across Southern Europe, and that more hard-hitting strategies are needed.

Mediterranean Diet Adherence and Subjective Well-Being in a Sample of Portuguese Adults

The Mediterranean diet (MD) and other lifestyle characteristics have been associated with well-being, a broad multiparameter concept that includes individual's subjective assessment of their own well-being (SWB). Some studies have suggested that diet influences SWB, thus, this work aimed to add novel information on the association of MD and SWB in a sample of Portuguese adults. Data on sociodemographic, economic, lifestyle, diet, and SWB were collected through a self-filled online questionnaire. MD adherence was assessed by the Mediterranean Diet Adherence Screener (MEDAS) score ]. Results showed a moderate adherence to the MD in 490 Portuguese adults (mean MEDAS of 7.4 ± 2.1). A higher MD adherence was found to be significantly positively associated with women, employed individuals, a higher number of meals per day, and those with frequent contact with nature (p-value < 0.0025, using Bonferroni adjustment). As a novelty, this study divided the participants into low SWB, medium SWB, and medium to high SWB profiles (3.9 ± 1.0; 6.2 ± 1.0; 8.2 ± 1.3, respectively; p-value < 0.05), which reported significantly increasing MEDAS scores (6.5 ± 2.1; 7.3 ± 2.1; 7.8 ± 1.9; respectively, p-value < 0.05).

Piperine: Old Spice and New Nutraceutical?

BACKGROUND

Many of the activities associated with pepper fruits have been attributed to piperine, the most active compound present in these spices.

OBJECTIVE

This paper aims to provide an overview of the known properties of piperine, i.e. piperine's chemistry, its physiological activity, documented interactions as a bioenhancer and reported data concerning its toxicity, antioxidant properties and anticancer activity.

DISCUSSION

It is known that piperine possesses several properties. In its interaction with other drugs, it can act as a bioavailability enhancer; this effect is also manifested in combination with other nutraceuticals, e.g. with curcumin, i.e. piperine can modify curcumin's antioxidant, anti-inflammatory, antimicrobial and anticancer effects. Piperine displays significant immunomodulating, antioxidant, chemopreventive and anticancer activity; these effects have been shown to be dose-dependent and tissue-specific. However, the main limitation associated with piperine seems to be its low bioavailability, a disadvantage that innovative formulations are overcoming.

CONCLUSION

It is predicted that an increasing number of studies will focus on piperine, especially those directed towards unraveling its properties at molecular level. The current knowledge about the action of piperine will form a foundation for ways to improve piperine's bioavailability e.g. exploitation of different carrier systems. The therapeutical applications of this compound will be clarified, and piperine will be recognized as an important nutraceutical.

Factors influencing the cardiometabolic response to (poly)phenols and phytosterols: a review of the COST Action POSITIVe activities

Purpose

Evidence exists regarding the beneficial effects of diets rich in plant-based foods regarding the prevention of cardiometabolic diseases. These plant-based foods are an exclusive and abundant source of a variety of biologically active phytochemicals, including polyphenols, carotenoids, glucosinolates and phytosterols, with known health-promoting effects through a wide range of biological activities, such as improvements in endothelial function, platelet function, blood pressure, blood lipid profile and insulin sensitivity. We know that an individual’s physical/genetic makeup may influence their response to a dietary intervention, and thereby may influence the benefit/risk associated with consumption of a particular dietary constituent. This inter-individual variation in responsiveness has also been described for dietary plant bioactives but has not been explored in depth. To address this issue, the European scientific experts involved in the COST Action POSITIVe systematically analyzed data from published studies to assess the inter-individual variation in selected clinical biomarkers associated with cardiometabolic risk, in response to the consumption of plant-based bioactives (poly)phenols and phytosterols. The present review summarizes the main findings resulting from the meta-analyses already completed.

Results

Meta-analyses of randomized controlled trials conducted within POSITIVe suggest that age, sex, ethnicity, pathophysiological status and medication may be responsible for the heterogeneity in the biological responsiveness to (poly)phenol and phytosterol consumption and could lead to inconclusive results in some clinical trials aiming to demonstrate the health effects of specific dietary bioactive compounds. However, the contribution of these factors is not yet demonstrated consistently across all polyphenolic groups and cardiometabolic outcomes, partly due to the heterogeneity in trial designs, low granularity of data reporting, variety of food vectors and target populations, suggesting the need to implement more stringent reporting practices in the future studies. Studies investigating the effects of genetic background or gut microbiome on variability were limited and should be considered in future studies.

Conclusion

Understanding why some bioactive plant compounds work effectively in some individuals but not, or less, in others is crucial for a full consideration of these compounds in future strategies of personalized nutrition for a better prevention of cardiometabolic disease. However, there is also still a need for the development of a substantial evidence-base to develop health strategies, food products or lifestyle solutions that embrace this variability.

A balanced diet, rich in plant-based foods is known for the prevention of obesity, diabetes, and cardiovascular disease risk.

(Poly)phenols and phytosterols displayed a range of biological effects of relevance to contribute to the cardiometabolic health benefits of plant foods

However, inter-individual variability in response to plant food bioactive consumption exists, and there is a need to understand the causes of this variation.

Analysis of published RCTs examining impact of consumption of (poly)phenols and phytosterols on cardiometabolic risk factors demonstrated that a number of factors including age, sex, adiposity and health status could contribute to the effect demonstrated within these studies.

Genome and microbiome studies will help identify what may be causing this variation.

More studies, specifically designed to investigate individual variation are needed to fully understand the factors responsible for and the impact of this variation

Once fully understood, such variation should be used in directing personalised nutrition advice.

European contribution to the study of ROS: A summary of the findings and prospects for the future from the COST action BM1203 (EU-ROS)

The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associated with oxidative stress established the theory of oxidative stress as a trigger of diseases that can be corrected by antioxidant therapy. However, while experimental studies support this thesis, clinical studies still generate controversial results, due to complex pathophysiology of oxidative stress in humans. For future improvement of antioxidant therapy and better understanding of redox-associated disease progression detailed knowledge on the sources and targets of RONS formation and discrimination of their detrimental or beneficial roles is required. In order to advance this important area of biology and medicine, highly synergistic approaches combining a variety of diverse and contrasting disciplines are needed.

Vitamin E supplementation in chronically hemodialyzed patients – influence on blood hemoglobin and plasma (anti)oxidant status

Abstract. Background: Disturbed oxidant/antioxidant status is involved in pathogenesis of anemia in end stage renal disease. There is evidence that vitamin E supplementation can increase blood hemoglobin in chronically hemodialyzed patients. However, the interindividual variation in response to the supplementation has not been fully addressed. Methods: 24 chronically hemodialyzed patients were supplemented with vitamin E (400 IU/day) in a period of two months. They had already been treated with erythropoiesis stimulating agents (ESA) and iron on a long-term basis, which was continued during the study period. A group of 20 healthy volunteers served as control subjects. Complete blood count, general biochemistry assays, the redox status by total thiols, oxidative stress by reactive oxygen metabolites, antioxidant status by biological antioxidant potential, and vitamin E (α- and γ- tocopherol) were measured before the start of supplementation, one month and two months later. Results: Overall, the vitamin E supplementation did not cause an increase of blood hemoglobin, hematocrit or red blood cells. However, 50 % of the patients with basal blood hemoglobin below 12.0 g/dL (N = 10) responded to the supplementation with its continuous increase. In addition, vitamin E exhibited a slight prooxidant effect only in the subgroup of patients with basal blood hemoglobin of ≥ 12.0 g/dL, two months after the start of supplementation (decreased total thiols: 300 ± 31 vs. 277 ± 36 µmol/L, p < 0.05; increased reactive oxygen metabolites: 183 ± 140 vs. 287 ± 112 CARR U, p > 0.05; decreased biological antioxidant potential: 2278 ± 150 vs. 2171 ± 126 µEq/L, p < 0.025), which coincided with their significantly increased serum α-tocopherol concentrations in comparison to the patients with basal blood hemoglobin below 12.0 g/dL (41.3 ± 7.2 vs. 59.9 ± 19.2 µmol/L, p < 0.025). Conclusions: When treated with ESA and iron on a long-term basis, the response to the vitamin E supplementation in chronically hemodialyzed patients is largely dependent on their basal blood hemoglobin and serum vitamin E concentrations.

Impact of Flavonols on Cardiometabolic Biomarkers: A Meta-Analysis of Randomized Controlled Human Trials to Explore the Role of Inter-Individual Variability

Several  epidemiological  studies  have  linked  flavonols  with  decreased  risk  of  cardiovascular  disease  (CVD).  However,  some  heterogeneity  in  the  individual  physiological  responses to the consumption of these compounds has been identified. This meta-analysis aimed to  study the effect of flavonol supplementation on biomarkers of CVD risk such as, blood lipids, blood  pressure and plasma glucose, as well as factors affecting their inter-individual variability. Data from  18 human randomized controlled trials were pooled and the effect was estimated using fixed or  random effects meta-analysis model and reported as difference in means (DM). Variability in the  response of blood lipids to supplementation with flavonols was assessed by stratifying various  population subgroups: age, sex, country, and health status. Results showed significant reductions  in total cholesterol (DM = -0.10 mmol/L; 95% CI: -0.20, -0.01), LDL cholesterol (DM = -0.14 mmol/L;  Nutrients 2017, 9, 117  2 of 21  95% CI: -0.21, 0.07), and triacylglycerol (DM = -0.10 mmol/L; 95% CI: -0.18, 0.03), and a significant  increase in HDL cholesterol (DM = 0.05 mmol/L; 95% CI: 0.02, 0.07). A significant reduction was also  observed in fasting plasma glucose (DM = -0.18 mmol/L; 95%CI: -0.29, -0.08), and in blood pressure  (SBP: DM = -4.84 mmHg; 95% CI: -5.64, -4.04; DBP: DM = -3.32 mmHg; 95% CI: -4.09, -2.55).  Subgroup analysis showed a more pronounced effect of flavonol intake in participants from Asian  countries and in participants with diagnosed disease or dyslipidemia, compared to healthy and  normal baseline values. In conclusion, flavonol consumption improved biomarkers of CVD risk,  however, country of origin and health status may influence the effect of flavonol intake on blood  lipid levels.

Cigarette Smoking and Oxidative Stress in Patients with Coronary Artery Disease

AIM:

To determine whether cigarette smoking, as a risk factor for CAD, affects (anti)oxidant status.

MATERIAL AND METHODS:

The study included patients with CAD, divided according to their smoking status and the number of cigarettes smoked during a day. Biological markers of oxidative stress (concentration of oxidants and activity of antioxidant enzymes) were measured in all subjects.

RESULTS:

The study included 300 patients with CAD, (average age of 63 ± 11 years), predominantly males. Of the total, 34.0% were active smokers, 23.0% were former smokers, and 43.0% were non-smokers. Most of the active smokers smoked 1-20 cigarettes/day. In terms of concentration of oxidants (MDA and HP) there was not a significant difference between smokers versus non-smokers. As for the activity of antioxidant enzymes (SOD, CAT and GPX), a statistically significant difference was found in the activity of GPX among the active smokers with CAD and the non-smokers with CAD (p = 0.039).

CONCLUSION:

Smoking as a risk factor for CAD is closely associated with increased oxidative stress, and the number of cigarettes smoked plays an important role in increasing the level of oxidative damage and reducing antioxidant defence.

Serum Biomarkers of (Anti)Oxidant Status for Epidemiological Studies

In this review, we disclose a selection of serum/plasma biomarkers of (anti)oxidant status related to nutrition, which can be used for measurements in large-scale epidemiological studies. From personal experience, we have come to the following proposal of a set of biomarkers for nutritional intake, (anti)oxidant status, and redox status. We have selected the individual antioxidant vitamins E and A, and the carotenoids which can be measured in large series by HPLC. In addition, vitamin C was selected, which can be measured by an auto-analyzer or HPLC. As a biomarker for oxidative stress, the ROM assay (reactive oxygen metabolites) was selected; for the redox status, the total thiol assay; and for the total antioxidant status the BAP assay (biological antioxidant potential). All of these biomarkers can be measured in large quantities by an auto-analyzer. Critical points in biomarker validation with respect to blood sampling, storage conditions, and measurements are discussed. With the selected biomarkers, a good set is presented for use in the risk assessment between nutrition and (chronic) diseases in large-scale epidemiological studies. Examples of the successful application of these biomarkers in large international studies are presented.

Clinical Relevance of Biomarkers of Oxidative Stress

SIGNIFICANCE

Oxidative stress is considered to be an important component of various diseases. A vast number of methods have been developed and used in virtually all diseases to measure the extent and nature of oxidative stress, ranging from oxidation of DNA to proteins, lipids, and free amino acids.

RECENT ADVANCES

An increased understanding of the biology behind diseases and redox biology has led to more specific and sensitive tools to measure oxidative stress markers, which are very diverse and sometimes very low in abundance.

CRITICAL ISSUES

The literature is very heterogeneous. It is often difficult to draw general conclusions on the significance of oxidative stress biomarkers, as only in a limited proportion of diseases have a range of different biomarkers been used, and different biomarkers have been used to study different diseases. In addition, biomarkers are often measured using nonspecific methods, while specific methodologies are often too sophisticated or laborious for routine clinical use.

FUTURE DIRECTIONS

Several markers of oxidative stress still represent a viable biomarker opportunity for clinical use. However, positive findings with currently used biomarkers still need to be validated in larger sample sizes and compared with current clinical standards to establish them as clinical diagnostics. It is important to realize that oxidative stress is a nuanced phenomenon that is difficult to characterize, and one biomarker is not necessarily better than others. The vast diversity in oxidative stress between diseases and conditions has to be taken into account when selecting the most appropriate biomarker.

Diurnal Variation of Hormonal and Lipid Biomarkers in a Molecular Epidemiology-Like Setting

Introduction

Many molecular epidemiology studies focusing on high prevalent diseases, such as metabolic disorders and cancer, investigate metabolic and hormonal markers. In general, sampling for these markers can occur at any time-point during the day or after an overnight fast. However, environmental factors, such as light exposure and food intake might affect the levels of these markers, since they provide input for the internal time-keeping system. When diurnal variation is larger than the inter-individual variation, time of day should be taken into account. Importantly, heterogeneity in diurnal variation and disturbance of circadian rhythms among a study population might increasingly occur as a result of our increasing 24/7 economy and related variation in exposure to environmental factors (such as light and food).

Aim

The aim of the present study was to determine whether a set of often used biomarkers shows diurnal variation in a setting resembling large molecular epidemiology studies, i.e., non-fasted and limited control possibilities for other environmental influences.

Results

We show that markers for which diurnal variation is not an issue are adrenocorticotropic hormone, follicle stimulating hormone, estradiol and high-density lipoprotein. For all other tested markers diurnal variation was observed in at least one gender (cholesterol, cortisol, dehydroepiandrosterone sulfate, free fatty acids, low-density lipoprotein, luteinizing hormone, prolactin, progesterone, testosterone, triglycerides, total triiodothyronine and thyroid-stimulating hormone) or could not reliably be detected (human growth hormone).

Discussion

Thus, studies investigating these markers should take diurnal variation into account, for which we provide some options. Furthermore, our study indicates the need for investigating diurnal variation (in literature or experimentally) before setting up studies measuring markers in routine and controlled settings, especially since time-of-day likely matters for many more markers than the ones investigated in the present study.

Mineral nutrient imbalance, total antioxidants level and DNA damage in common bean (Phaseolus vulgaris L.) exposed to heavy metals

The present study aimed to analyze the biological effects induced by bioaccumulation of metals in common bean (Phaseolus vulgaris L.). Effects of mineral nutrient imbalance, total antioxidants level and DNA damage induced by accumulation of heavy metals, were investigated in bean seedlings treated with two selected metal concentrations for 7 days. Metal content is analyzed by inductively coupled plasma - atomic emission spectrometer (ICP-AES), for total antioxidants level assessment the Ferric-Reducing Antioxidant Power (FRAP) assay is used and Random Amplified Polymorphic DNA (RAPD) method was applied for investigation of DNA damages. The increasing metal concentration in the treatment medium changed synchronously metal content in samples, and decreased total antioxidant activity in all samples with exception only for samples treated with Ni and Cd. The obtained "DNA fingerprints" demonstrated that the increasing metal concentrations induced changes in RAPD profiles (disappearance and/or appearance of bands in comparison with untreated control samples). The highest number of missing bands was observed in samples treated with zinc (total 4 bands) and nickel (total 4 bands) at both concentrations. These results suggested that mineral nutrient imbalance is involved in changes of antioxidant levels and DNA damages of the seedlings, which may help to understand the mechanism of metal toxicity in plants.

Oxidative stress and protein carbonylation in adipose tissue - implications for insulin resistance and diabetes mellitus

While historically considered simply as a depot for excess energy, white adipose tissue is a dynamically active endocrine organ capable of responding to a variety of efferent stimuli resulting in the synthesis and secretion of peptides, proteins and metabolites that serve as signal transducers to the peripheral and central circulation. Such regulation controls a variety of physiological processes including energy expenditure, food intake, reproductive capacity and responsiveness to insulin. Indeed, the accumulation of inflammatory cells in white adipose tissue is considered to be causative in the development of insulin resistance and eventually type 2 diabetes mellitus. A large body of evidence suggests that oxidative stress in adipose tissue not only correlates with insulin resistance but is also causative in its development. Moreover, using the available plasma oxidative stress biomarkers, many clinical studies have shown the presence of systemic oxidative stress in obese insulin resistant subjects, and its decrease after the successful treatment of obesity. In this review we emphasize the role of protein carbonylation in dysfunctional obese white adipose tissue and its metabolic implications. We focus on glutathione S-transferase A4 as the key enzyme for trans-4-hydroxy-2-nonenal and trans-4-oxo-2-nonenal removal from the cell, thus preventing protein carbonylation. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.