Studies on HDL associated enzymes under experimental hypercholesterolemia: possible modulation on selenium supplementation

Micronutrients, Phytochemicals and Mediterranean Diet: A Potential Protective Role against COVID-19 through Modulation of PAF Actions and Metabolism

The new coronavirus disease 2019 (COVID-19) pandemic is an emerging situation with high rates of morbidity and mortality, in the pathophysiology of which inflammation and thrombosis are implicated. The disease is directly connected to the nutritional status of patients and a well-balanced diet is recommended by official sources. Recently, the role of platelet activating factor (PAF) was suggested in the pathogenesis of COVID-19. In the present review several micronutrients (vitamin A, vitamin C, vitamin E, vitamin D, selenium, omega-3 fatty acids, and minerals), phytochemicals and Mediterranean diet compounds with potential anti-COVID activity are presented. We further underline that the well-known anti-inflammatory and anti-thrombotic actions of the investigated nutrients and/or holistic dietary schemes, such as the Mediterranean diet, are also mediated through PAF. In conclusion, there is no single food to prevent coronavirus Although the relationship between PAF and COVID-19 is not robust, a healthy diet containing PAF inhibitors may target both inflammation and thrombosis and prevent the deleterious effects of COVID-19. The next step is the experimental confirmation or not of the PAF-COVID-19 hypothesis.

Selenium supplementation during pregnancy and lactation promotes metabolic changes in Wistar rats' offspring

Epidemiological and animal studies have demonstrated a strong association between selenium (Se) supplementation and metabolic disorders, we aimed to evaluate whether maternal Se supplementation was able to change metabolic parameters in rats' offspring. Moreover, as Se is a deiodinase (DIO) cofactor, we decided to investigate how thyroid hormones (THs) would be involved in such metabolic changes. Thereby, two groups (n = 6, ~250 g) of female Wistar rats underwent isotonic saline or sodium selenite (1 mg/kg, p.o.) treatments. Although there were no significant differences in body weight between groups, the Se treatment during pregnancy and lactation increased milk intake and the visceral white adipose tissue (WAT) in offspring. The rats whose mothers were treated with Se also presented an improvement in the glucose tolerance test and in the glucose-stimulated insulin secretion. Regarding the lipid metabolism, the Se group had a reduction of triglycerides in the liver and in WAT. These metabolic changes were accompanied by an increase in serum triiodothyronine (T3 ) and in DIO 2 expression in brown adipose tissue (BAT). We further demonstrate an increased expression of peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1α) and nuclear respiratory factor-1 (NRF-1) mRNA in the liver. In adulthood offspring, Se supplementation programs thyroid function, glucose homeostasis, and feeding behaviour. Taken together, there is no indication that Se programming causes insulin resistance. Moreover, we conjecture that these metabolic responses are induced by increased thyroxine (T4 ) to T3 conversion by DIO2 in BAT and mediated by altered transcription factors expression associated with oxidative metabolism control in the liver.

Assessing the Efficacy of Dietary Selenomethionine Supplementation in the Setting of Cardiac Ischemia/Reperfusion Injury

Oxidative stress is a major hallmark of cardiac ischemia/reperfusion (I/R) injury. This partly arises from the presence of activated phagocytes releasing myeloperoxidase (MPO) and its production of hypochlorous acid (HOCl). The dietary supplement selenomethionine (SeMet) has been shown to bolster endogenous antioxidant processes as well as readily react with MPO-derived oxidants. The aim of this study was to assess whether supplementation with SeMet could modulate the extent of cellular damage observed in an in vitro cardiac myocyte model exposed to (patho)-physiological levels of HOCl and an in vivo rat model of cardiac I/R injury. Exposure of the H9c2 cardiac myoblast cell line to HOCl resulted in a dose-dependent increase in necrotic cell death, which could be prevented by SeMet supplementation and was attributed to SeMet preventing the HOCl-induced loss of mitochondrial inner trans-membrane potential, and the associated cytosolic calcium accumulation. This protection was credited primarily to the direct oxidant scavenging ability of SeMet, with a minor contribution arising from the ability of SeMet to bolster cardiac myoblast glutathione peroxidase (GPx) activity. In vivo, a significant increase in selenium levels in the plasma and heart tissue were seen in male Wistar rats fed a diet supplemented with 2 mg kg⁻¹ SeMet compared to controls. However, SeMet-supplementation demonstrated only limited improvement in heart function and did not result in better heart remodelling following I/R injury. These data indicate that SeMet supplementation is of potential benefit within pathological settings where excessive HOCl is known to be generated but has limited efficacy as a therapeutic agent for the treatment of heart attack.

Current Therapies Focused on High-Density Lipoproteins Associated with Cardiovascular Disease

High-density lipoproteins (HDL) comprise a heterogeneous family of lipoprotein particles divided into subclasses that are determined by density, size and surface charge as well as protein composition. Epidemiological studies have suggested an inverse correlation between High-density lipoprotein-cholesterol (HDL-C) levels and the risk of cardiovascular diseases and atherosclerosis. HDLs promote reverse cholesterol transport (RCT) and have several atheroprotective functions such as anti-inflammation, anti-thrombosis, and anti-oxidation. HDLs are considered to be atheroprotective because they are associated in serum with paraoxonases (PONs) which protect HDL from oxidation. Polyphenol consumption reduces the risk of chronic diseases in humans. Polyphenols increase the binding of HDL to PON1, increasing the catalytic activity of PON1. This review summarizes the evidence currently available regarding pharmacological and alternative treatments aimed at improving the functionality of HDL-C. Information on the effectiveness of the treatments has contributed to the understanding of the molecular mechanisms that regulate plasma levels of HDL-C, thereby promoting the development of more effective treatment of cardiovascular diseases. For that purpose, Scopus and Medline databases were searched to identify the publications investigating the impact of current therapies focused on high-density lipoproteins.

Selenium supplementation lowers insulin resistance and markers of cardio-metabolic risk in patients with congestive heart failure: a randomised, double-blind, placebo-controlled trial

This study was carried out to evaluate the effects of Se supplementation on metabolic profiles in patients with congestive heart failure (CHF). This randomised double-blind, placebo-controlled trial was performed among fifty-three subjects with CHF, aged 45–85 years old. Subjects were randomly allocated into two groups to take either 200 µg/d of Se as Se yeast (n 26) or placebo (n 27) for 12 weeks. Metabolic profiles were assessed at baseline and at the end of trial. Compared with the placebo, Se supplementation led to significant reductions in serum insulin (−18·41 (sd 27·53) v. +13·73 (sd 23·63) pmol/l, P<0·001), homoeostatic model of assessment for insulin resistance (−1·01 (sd 1·61) v. +0·55 (sd 1·20), P<0·001) and a significant increase in quantitative insulin sensitivity check index (QUICKI) (+0·007 (sd 0·03) v. −0·01 (sd 0·01), P=0·007). In addition, Se supplementation significantly decreased LDL-cholesterol (−0·23 (sd 0·29) v. −0·04 (sd 0·28) mmol/l, P=0·03) and total-:HDL-cholesterol ratio (−0·47 (sd 0·31) v. −0·06 (sd 0·42), P<0·001), and significantly increased HDL-cholesterol levels (+0·18 (sd 0·19) v. +0·02 (sd 0·13) mmol/l, P=0·001) compared with the placebo. In addition, taking Se supplements was associated with a significant reduction in high-sensitivity C-reactive protein (hs-CRP) (−1880·8 (sd 3437·5) v. +415·3 (sd 2116·5) ng/ml, P=0·01), and a significant elevation in plasma total antioxidant capacity (TAC) (+30·9 (sd 118·0) v. −187·9 (sd 412·7) mmol/l, P=0·004) and total glutathione levels (+33·7 (sd 130·4) v. −39·2 (sd 132·8) µmol/l, P=0·003) compared with the placebo. When we applied Bonferroni correction for multiple outcome testing, QUICKI (P=0·11), LDL-cholesterol (P=0·51), hs-CRP (P=0·17), TAC (P=0·06) and GSH (P=0·05) became non-significant, and other metabolic profiles did not alter. Overall, our study supported that Se supplementation for 12 weeks to patients with CHF had beneficial effects on insulin metabolism and few markers of cardio-metabolic risk.

Interaction of genotype and diet on small intestine microbiota of Japanese quail fed a cholesterol enriched diet

Our previous study has shown that genetic selection for susceptibility/resistance to diet-induced atherosclerosis has affected the Japanese quail's cecal environment to accommodate distinctly different cecal microbiota. In this study, we fed the Atherosclerosis-resistant (RES) and -susceptable (SUS) quail a regular and a cholesterol enriched diet to examine the interaction of host genotype and diet on the diversity, composition, and metabolic functions of the duodenal and ileal microbiota with relations to atherosclerosis development. In the duodenal content, 9 OTUs (operational taxonomic units) were identified whose abundance had significant positive correlations with plasma total cholesterol, LDL level and/or LDL/HDL ratio. In the ileal content, 7 OTUs have significant correlation with plasma HDL. Cholesterol fed RES hosted significantly less Escherichia and unclassified Enterobacteriaceae (possibly pathogenic) in their duodenum than SUS fed the same diet. Dietary cholesterol significantly decreased the duodenal microbiome of SUS's biosynthesis of Ubiquinone and other terpenoid-quinone. Cholesterol fed RES had significantly more microbiome genes for Vitamin B6, selenocompound, taurine and hypotaurine, and Linoleic acid metabolism; Bisphenol degradation; primary bile acid, and butirosin and neomycin biosynthesis than SUS on the same diet. Microbiome in the ileum and ceca of RES contributed significantly towards the resistance to diet induced atherosclerosis.

Supplementation of Micronutrient Selenium in Metabolic Diseases: Its Role as an Antioxidant

Selenium is an essential mineral naturally found in soil, water, and some of the food. As an antioxidant, it is one of the necessary trace elements in human body and has been suggested as a dietary supplement for health benefit. Although the human body only needs a trace amount of selenium every day, plenty of recent studies have revealed that selenium is indispensable for maintaining normal functions of metabolism. In this study, we reviewed the antioxidant role of nutritional supplementation of selenium in the management of major chronic metabolic disorders, including hyperlipidaemia, hyperglycaemia, and hyperphenylalaninemia. Clinical significance of selenium deficiency in chronic metabolic diseases was elaborated, while clinical and experimental observations of dietary supplementation of selenium in treating chronic metabolic diseases, such as diabetes, arteriosclerosis, and phenylketonuria, were summarized. Toxicity and recommended dose of selenium were discussed. The mechanism of action was also proposed via inspecting the interaction of molecular networks and predicting target protein such as xanthine dehydrogenase in various diseases. Future direction in studying the role of selenium in metabolic disorders was also highlighted. In conclusion, highlighting the beneficial role of selenium in this review would advance our knowledge of the dietary management of chronic metabolic diseases.

The Search for Dietary Supplements to Elevate or Activate Circulating Paraoxonases

Low levels of paraoxonase 1 (PON1) have been associated with the development of several pathological conditions, whereas high levels have been shown to be anti-atherosclerotic in mouse models. These findings suggest that PON1 could be a good surrogate biomarker. The other members of the family, namely PON2 and PON3, the role of which has been much less studied, deserve more attention. This paper provides a systematic review of current evidence concerning dietary supplements in that regard. Preliminary studies indicate that the response to dietary supplements may have a nutrigenetic aspect that will need to be considered in large population studies or in clinical trials. A wide range of plant preparations have been found to have a positive action, with pomegranate and some of its components being the best characterized and Aronia melanocarpa one of the most active. Flavonoids are found in the composition of all active extracts, with catechins and genistein being the most promising agents for increasing PON1 activity. However, some caveats regarding the dose, length of treatment, bioavailability, and stability of these compounds in formulations still need to be addressed. Once these issues have been resolved, these compounds could be included as nutraceuticals and functional foods capable of increasing PON1 activity, thereby helping with the long-term prevention of atherosclerosis and other chronic ailments.

Effect of Inorganic Dietary Selenium Supplementation on Selenoprotein and Lipid Metabolism Gene Expression Patterns in Liver and Loin Muscle of Growing Lambs

Effect of selenium (Se) supplementation on the selenoprotein and lipid metabolism gene expression patterns in ruminants, especially in lambs is not yet fully understood. The aim of study was to evaluate the effect of Se supplementation on the messenger RNA (mRNA) expression patterns of selected selenoproteins and genes related to lipid metabolism in growing lambs. The experiment was conducted on 48 Polish Merino lambs divided into two groups (n = 24): control (C)-lambs fed with a basal diet (BD) with no Se supplementation, and supplemented (S)-lambs fed with a BD, supplemented with 0.5 mg Se/kg as sodium selenate for 8 weeks. Expression of 12 selenoproteins and six genes related to lipid metabolism was analyzed in the liver and longissimus dorsi (LD) muscle of growing lambs by qPCR. Significant differences were found in the expression of GPX1, GPX2, SEPM, SEPW1, SEP15, SEPGS2, and TXNRD1 in the liver, and GPX1, SEPP1, SEPN1, SEPW1, SEP15, and MSRB1 in the LD muscle between S and C lambs. Se supplementation mainly upregulated SEPW1, SEP15 (P < 0.001; P < 0.01) mRNA expression in the liver, and GPX1, SEPP1, SEPN1, SEPW1 (P < 0.001; P < 0.01) in the muscle of S group. On the other hand, significant decrease in GPX2 (P < 0.01), SEPM (P < 0.001), and SEPHS2 (P < 0.01) mRNA expression levels were observed in the liver of S group of lambs. Se supplementation did not affect PON1, LXRα, and PPARα mRNA expression levels, but a significant increase in mRNA levels of APOE and LPL in the LD muscle (P < 0.05) as well as LPL (P < 0.05) in the liver were noticed in the group of Se supplemented lambs. Our study confirmed that, in lambs, similarly to other species, mRNA expression patterns of several selenoproteins highly depend on dietary Se levels, and their expression is ruled by hierarchical principles and tissue-specific mechanisms. Moreover, the study showed that changes Se intake leads to different levels of genes expression related with lipid metabolism.

The hypolipidemic action of a diet supplemented with p,p'-methoxyl-diphenyl diselenide is not directly related to its antioxidant property

The present study investigated whether a p,p'-methoxyl-diphenyl diselenide (MeOPhSe)2-supplemented diet causes toxicity in rats. A second aim of this study was to determine whether a 10 ppm (MeOPhSe)2-supplemented diet has hypolipidemic effect on Triton WR-1339-induced hyperlipidemia in rats. To rule out the antioxidant property of (MeOPhSe)2 in its hypolipidemic action, parameters of oxidative stress were carried out. Wistar rats were fed with 3, 10, or 30 ppm of (MeOPhSe)2-supplemented diet for 30 days. None of (MeOPhSe)2-supplemented diets caused alteration in general parameters of toxicity and lipid profile of rats. The hypolipidemic effect of 10 ppm of (MeOPhSe)2-supplemented diet on rats treated with Triton WR-1339 (400 mg/kg, intraperitoneal) was investigated. The (MeOPhSe)2-supplemented diet partially protected against the levels of total cholesterol (TC) and non-HDL-C and reduced the atherogenic index (AI) increased by Triton WR-1339 in rats. A positive correlation between TC and triglyceride levels (r = 0.679) and non-HDL-C levels (r = 0.929) and AI (r = 0.889) was demonstrated. Triton WR-1339 altered parameters of oxidative stress in livers of rats but (MeOPhSe)2-supplemented diet did not protect against these alterations. The results demonstrated that the hypolipidemic action of (MeOPhSe)2-supplemented diet is not directly related to its antioxidant property and devoid of systemic toxicity in rats at the parameters analyzed.

Metabolic response to selenium supplementation in women with polycystic ovary syndrome: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

We are aware of no study examining the effects of selenium supplementation on metabolic profiles of patients with polycystic ovary syndrome (PCOS). This study was conducted to evaluate the effects of selenium supplementation on glucose homeostasis parameters and lipid concentrations in women with PCOS.

DESIGN, PATIENTS AND MEASUREMENTS

This randomized, double-blind, placebo-controlled trial was conducted among 70 women diagnosed with PCOS and aged 18-40 years old. Participants were randomly divided into two groups to receive 200 μg per day selenium supplements (N = 35) or placebo (N = 35) for 8 weeks. Fasting blood samples were taken at baseline and after 8 weeks intervention to quantify glucose, insulin and lipid concentrations.

RESULTS

After 8 weeks of intervention, subjects who received selenium supplements had significantly decreased serum insulin levels (-29·83 ± 47·29 vs +9·07 ± 77·12 pmol/l, P = 0·013), homeostasis model of assessment-insulin resistance (HOMA-IR) (-1·15 ± 1·81 vs +0·42 ± 3·09, P = 0·011), homeostatic model assessment-beta-cell function (HOMA-B) (-19·06 ± 30·95 vs +4·55 ± 47·99, P = 0·017) and increased quantitative insulin sensitivity check index (QUICKI) (+0·03 ± 0·04 vs +0·0009 ± 0·05, P = 0·032) compared with placebo. In addition, supplementation with selenium resulted in a significant reduction in serum triglycerides (-0·14 ± 0·55 vs +0·11 ± 0·30 mmol/l, P = 0·025) and VLDL-C concentrations (-0·03 ± 0·11 vs +0·02 ± 0·06 mmol/l, P = 0·025) compared with placebo.

CONCLUSIONS

In conclusion, 200 microgram per day selenium supplementation for 8 weeks among PCOS women had beneficial effects on insulin metabolism parameters, triglycerides and VLDL-C levels; however, it did not affect FPG and other lipid profiles.

PON1 and Mediterranean Diet

The Mediterranean diet has been proven to be highly effective in the prevention of cardiovascular diseases. Paraoxonase 1 (PON1) has been implicated in the development of those conditions, especially atherosclerosis. The present work describes a systematic review of current evidence supporting the influence of Mediterranean diet and its constituents on this enzyme. Despite the differential response of some genetic polymorphisms, the Mediterranean diet has been shown to exert a protective action on this enzyme. Extra virgin olive oil, the main source of fat, has been particularly effective in increasing PON1 activity, an action that could be due to low saturated fatty acid intake, oleic acid enrichment of phospholipids present in high-density lipoproteins that favor the activity, and increasing hepatic PON1 mRNA and protein expressions induced by minor components present in this oil. Other Mediterranean diet constituents, such as nuts, fruits and vegetables, have been effective in modulating the activity of the enzyme, pomegranate and its compounds being the best characterized items. Ongoing research on compounds isolated from all these natural products, mainly phenolic compounds and carotenoids, indicates that some of them are particularly effective, and this may enhance the use of nutraceuticals and functional foods capable of potentiating PON1 activity.

Dietary antioxidants (selenium and N-acetylcysteine) modulate paraoxonase 1 (PON1) in PCB 126-exposed rats

Environmental pollutants polychlorinated biphenyls (PCBs), especially dioxin-like PCBs, cause oxidative stress and associated toxic effects, including cancer and possibly atherosclerosis. We previously reported that PCB 126, the most potent dioxin-like PCB congener, not only decreases antioxidants such as hepatic selenium (Se), Se-dependent glutathione peroxidase, and glutathione (GSH) but also increases levels of the antiatherosclerosis enzyme paraoxonase 1 (PON1) in liver and serum. To probe the interconnection of these three antioxidant systems, Se, GSH, and PON1, we examined the influence of varying levels of dietary Se and N-acetylcysteine (NAC), a scavenger of reactive oxygen species (ROS) and precursor for GSH synthesis, on PON1 in the absence and presence of PCB 126 exposure. Male Sprague-Dawley rats, fed diets with differing Se levels (0.02, 0.2, or 2 ppm) or NAC (1%), were treated with a single intraperitoneal injection of corn oil or various doses of PCB 126 and euthanized 2 weeks later. PCB 126 significantly increased liver PON1 mRNA, protein level and activity, and serum PON1 activity in all dietary groups but did not consistently increase thiobarbituric acid levels (thiobarbituric acid reactive substances, TBARS), an indicator of lipid oxidation and oxidative stress, in liver or serum. Inadequate (high or low) dietary Se decreased baseline and PCB 126-induced aryl hydrocarbon receptor (AhR) expression but further increased PCB 126-induced cytochrome P450 1A1 (CYP1A1) expression, the enzyme believed to be the cause for PCB 126-induced oxidative stress. In addition, a significant inverse relationship was observed not only between dietary Se levels and PON1 mRNA and PON1 activity but also with TBARS levels in the liver, suggesting significant antioxidant protection from dietary Se. NAC lowered serum baseline TBARS levels in controls and increased serum PON1 activity but lowered liver PON1 activities in animals treated with 1 μmol/kg PCB 126, suggesting antioxidant activity by NAC primarily in serum. These results also show an unexpected predominantly inverse relationship between Se or NAC and PON1 during control and PCB 126 exposure conditions. These interactions should be further explored in the development of dietary protection regimens.

Selenium significantly inhibits adipocyte hypertrophy and abdominal fat accumulation in OLETF rats via induction of fatty acid β-oxidation

A combination of selenium (Se) with other trace element is associated with partially modulate fatty acid distribution as well as reduction of the body weight and feed efficiency. To investigate whether or not Se treatment has an impact on lipid metabolism, we examined the levels of lipid metabolism-related factors, including abdominal fat, adiponectin, cholesterol, very long chain dehydrogenase (VLCAD), and medium chain acyl-CoA dehydrogenase (MCAD) in 20-week-old Otsuka Long-Evans Tokushima Fatty (OLETF) rats following sodium selenite treatment for 2 weeks. Herein, we observed that (a) Se treatment induced insulin-like effects by lowering the serum glucose level in rats; (b) Se-treated rats showed significance values decreases in abdominal fat mass, adipocyte size, and adiponectin, which are associated with lipid metabolism; (c) Se treatment led to reduced levels of cholesterol, triglycerides, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) cholesterol; (d) fat tissue in Se-treated rats displayed significantly lower expression of adipocyte marker genes along with increased expression of VLCAD and MCAD; and (e) fatty liver formation and β-oxidation gene expression were both significantly reduced in liver tissue of Se-treated rats. Therefore, our results suggest that Se may induce inhibition of adipocyte hypertrophy and abdominal fat accumulation along with suppression of fatty liver formation by the differential regulation of the gene expression for fatty acid β-oxidation in the OLETF model.

Aqueous extract of Liriope platyphylla, a traditional Chinese medicine, significantly inhibits abdominal fat accumulation and improves glucose regulation in OLETF type II diabetes model rats

Liriope platyphylla is a medical herb that has long been used in Korea and China to treat cough, sputum, neurodegenerative disorders, obesity, and diabetes. The aims of this study were to determine the antidiabetic and antiobesity effects of aqueous extract of L. platyphylla (AEtLP) through glucose and lipid regulation in both pre-diabetes and obesity stage of type II diabetes model. Two concentrations of AEtLP were orally administrated to OLETF (Otsuka Long-Evans Tokushima Fatty) rats once a day for 2 weeks, after which changes in glucose metabolism and fat accumulation were measured. Abdominal fat mass dramatically decreased in AEtLP-treated OLETF rats, whereas glucose concentration slightly decreased in all AEtLP-treated rats. However, compared to vehicle-treated OLETF rats, only AEtLP10 (10% concentration)-treated OLETF rats displayed significant induction of insulin production, whereas AEtLP5 (5% concentration)-treated OLETF rats showed a lower level of insulin. Although serum adiponectin level increased in only AEtLP5-treated rats, significant alteration of lipid concentration was detected in AEtLP5-treated OLETF rats. Expression of Glut-1 decreased in all AEtLP-treated rats, whereas Akt phosphorylation increased only in AEtLP10-treated OLETF rats. Furthermore, the pattern of Glut-3 expression was very similar with that of Glut-1 expression, which roughly corresponded with the phosphorylation of c-Jun N-teminal kinase (JNK) and p38 in the mitogen-activated protein kinase pathway. Therefore, these findings suggest that AEtLP should be considered as a therapeutic candidate during pre-diabetes and obesity stage capable of inducing insulin secretion from pancreatic β-cells, glucose uptake in liver cells, as well as a decrease in fat and lipid accumulation.

Regulation of paraoxonase 1 (PON1) in PCB 126-exposed male Sprague Dawley rats

3,3',4,4',5-Pentachlorobiphenyl (PCB 126), an aryl hydrocarbon receptor (AhR) agonist and most potent dioxin-like PCB congener, significantly alters gene expression, lipid metabolism, and oxidative stress in the liver. PON1, an antioxidant and anti-atherogenic enzyme, is produced in the liver and secreted into the blood where it is incorporated into high density lipoprotein (HDL) and protects LDL and cellular membranes against lipid peroxidation. To explore the regulation of PON1, male Sprague-Dawley rats were treated with ip injections of corn oil or 1 μmol/kg or 5 μmol/kg PCB 126 and euthanized up to two weeks afterwards. Serum total and HDL-cholesterol were increased by low dose and decreased by high dose exposure, while LDL-cholesterol was unchanged. PCB 126 significantly increased hepatic PON1 gene expression and liver and serum PON1 activities. Liver and serum thiobarbituric acid reactive substances levels were not elevated except for high dose and long exposure times. Serum antioxidant capacity was unchanged across all exposure doses and time points. This study, the first describing the regulation of gene expression of PON1 by a PCB congener, raises interesting questions whether elevated PON1 is able to ameliorate PCB 126-induced lipid peroxidation and whether serum PON1 levels may serve as a new biomarker of exposure to dioxin-like compounds.

Antioxidant and inflammatory aspects of lipoprotein-associated phospholipase A₂ (Lp-PLA₂): a review

The association of cardiovascular events with Lp-PLA₂ has been studied continuously today. The enzyme has been strongly associated with several cardiovascular risk markers and events. Its discovery was directly related to the hydrolysis of the platelet-activating factor and oxidized phospholipids, which are considered protective functions. However, the hydrolysis of bioactive lipids generates lysophospholipids, compounds that have a pro-inflammatory function. Therefore, the evaluation of the distribution of Lp-PLA₂ in the lipid fractions emphasized the dual role of the enzyme in the inflammatory process, since the HDL-Lp-PLA₂ enzyme contributes to the reduction of atherosclerosis, while LDL-Lp-PLA₂ stimulates this process. Recently, it has been verified that diet components and drugs can influence the enzyme activity and concentration. Thus, the effects of these treatments on Lp-PLA₂ may represent a new kind of prevention of cardiovascular disease. Therefore, the association of the enzyme with the traditional assessment of cardiovascular risk may help to predict more accurately these diseases.

Relationship of oxidized low density lipoprotein with lipid profile and oxidative stress markers in healthy young adults: a translational study

Background

Despite oxidized low density lipoprotein (ox-LDL) plays important roles in the pro-inflammatory and atherosclerotic processes, the relationships with metabolic and oxidative stress biomarkers have been only scarcely investigated in young adult people. Thus, the aim of this study was to assess plasma ox-LDL concentrations and the potential association with oxidative stress markers as well as with anthropometric and metabolic features in healthy young adults.

Methods

This study enrolled 160 healthy subjects (92 women/68 men; 23 ± 4 y; 22.0 ± 2.9 kg/m²). Anthropometry, body composition, blood pressure, lifestyle features, biochemical data, and oxidative stress markers were assessed with validated tools. Selenium, copper, and zinc nail concentrations were measured by atomic absorption spectrophotometry.

Results

Total cholesterol (TC), LDL-c and uric acid concentrations, TC-to-HDL-c ratio, and glutathione peroxidase (GPx) activity were positive predictors of ox-LDL concentrations, while nail selenium level (NSL) was a negative predictor, independently of gender, age, smoking status, physical activity. Those individuals included in the highest tertile of GPx activity (≥611 nmol/[mL/min]) and of NSL (≥430 ng/g of nail) had higher and lower ox-LDL concentrations, respectively, independently of the same covariates plus truncal fat or body mass index, and total cholesterol or LDL-c concentrations.

Conclusions

Ox-LDL concentrations were significantly associated with lipid biomarkers, GPx activity, uric acid concentration, and NSL, independently of different assayed covariates, in young healthy adults. These findings jointly suggest the early and complex relationship between lipid profile and redox status balance.

Effect of walnut-enriched meat on the relationship between VCAM, ICAM, and LTB4 levels and PON-1 activity in ApoA4 360 and PON-1 allele carriers at increased cardiovascular risk

BACKGROUND/OBJECTIVE

Cardiovascular risk depends largely on paraoxonase (PON-1) and apolipoprotein A4 (APOA4) gene polymorphisms. To compare the effects of consumption of walnut-enriched meat versus low-fat meat (LM) on selected soluble adhesion molecules and leukotrienes (LTB4).

SUBJECTS/METHODS

In all 22 subjects at increased cardiovascular risk were taken. It is a non-blinded, cross-over, placebo-controlled study. Two 5-week experimental periods separated by 4-6 week wash-out interval. Participants consumed walnut-enriched meat during one period and LM during the other. Diet characteristics, HDLc, Apo A1, paraoxonase, sVCAM-1, sICAM-1 and LTB4 were analysed. PON-1 55, PON-1 192 and APOA4 360 polymorphism effects were also assessed.

RESULTS

Individuals consuming walnut-enriched meat displayed higher paraoxonase activity (P<0.001), lower levels of sICAM and aVCAM (P=0.046, P=0.012, respectively) and leukotriene B4 (P=0.044), and lower paraoxonase-1/HDLc and paraoxonase-1/Apo A1 ratios (both, P<0.001) than those consuming LM. Paraoxonase levels correlated negatively with those of sICAM (r=-0.471, P<0.01). Significant decreases (at least P<0.05) were observed in sICAM concentrations in PON-1 55LM+MM, PON-1 QQ192 and APOA4-2 carriers while decreases in sVCAM in QR+RR and APOA4-1 carriers were observed. Paraoxonase-1/HDLc and paraoxonase-1/Apo A1 ratios were significantly influenced by paraoxonase polymorphisms.

CONCLUSIONS

Walnut-enriched meat appears as a functional meat as consumed in the framework of a mix diet lowered the concentration of some selected inflammatory chemoattractant biomarkers. This effect was largely influenced by PON-1 and Apo A4-360 polymorphisms.