Paraoxonase and coronary heart disease

The impact of synbiotic on serum sCD163/sTWEAK, paraoxonase 1, and lipoproteins in patients with chronic heart failure: a randomized, triple-blind, controlled trial

Cardiovascular disease is one of the leading causes of death worldwide. Evidence suggests that alterations in the gut microbiome could play a role in cardiovascular diseases, including heart failure. The purpose of this study was to evaluate the effect of synbiotics on serum paraoxonase 1(PON1), soluble CD163/soluble TNF-like weak inducer of apoptosis (sCD163/sTWEAK), and lipid profile, which are involved in heart failure in patients with chronic heart failure. In this triple-blind randomized clinical trial, 90 eligible patients were included in the study. They were randomly assigned to receive one capsule (500 mg) of synbiotics or a placebo daily for ten weeks. Serum PON1, sCD163/sTWEAK, and lipid profiles were measured at the beginning and end of the study. The data were analyzed by SPSS 24, and the p-value < 0.05 was considered statistically significant. Among 90 patients who met the inclusion criteria, 80 completed the study. The primary outcomes showed a small effect on sTWEAK, with an adjusted standard mean difference (SMD) of 0.2. However, no significant changes were observed in sCD163/sTWEAK (SMD: 0.16). Secondary outcomes indicated no changes in PON1, total cholesterol (TC), or LDL-C levels. However, there was an increase in HDL-C levels (adjusted SMD: 0.46, 95% CI: 0.02-0.91) and a decrease in TG and TC/HDL levels (adjusted SMD: - 0.5 and - 0.3, respectively) in the synbiotic group. A favorable effect of synbiotics on sTWEAK, HDL, TG, and TC/HDL of patients with heart failure was observed, but no statistically significant effect was found on sCD163/sTWEAK, PON1, LDL, and TC factors.

Effect of Carotenoids on Paraoxonase-1 Activity and Gene Expression

Paraoxonase 1 (PON1) is an antioxidant enzyme attached to HDL with an anti-atherogenic potential. It protects LDL and HDL from lipid peroxidation. The enzyme is sensitive to various modulating factors, such as genetic polymorphisms as well as pharmacological, dietary (including carotenoids), and lifestyle interventions. Carotenoids are nutritional pigments with antioxidant activity. The aim of this review was to gather evidence on their effect on the modulation of PON1 activity and gene expression. Carotenoids administered as naturally occurring nutritional mixtures may present a synergistic beneficial effect on PON1 status. The effect of carotenoids on the enzyme depends on age, ethnicity, gender, diet, and PON1 genetic variation. Carotenoids, especially astaxanthin, β-carotene, and lycopene, increase PON1 activity. This effect may be explained by their ability to quench singlet oxygen and scavenge free radicals. β-carotene and lycopene were additionally shown to upregulate PON1 gene expression. The putative mechanisms of such regulation involve PON1 CpG-rich region methylation, Ca(2+)/calmodulin-dependent kinase II (CaMKKII) pathway induction, and upregulation via steroid regulatory element-binding protein-2 (SREBP-2). More detailed and extensive research on the mechanisms of PON1 modulation by carotenoids may lead to the development of new targeted therapies for cardiovascular diseases.

The effect of paraoxonase 1 (PON1) gene polymorphisms T(-107)C and L55M and diet composition on serum PON1 activity in women

OBJECTIVE

The aim of this study was to evaluate the serum activity of PON1 in women according to SNPs L55M and T-107C and diet composition.

METHODS

Blood and serum samples from 26 women were used. DNA extraction, PCR and digestion with restriction enzymes of the PCR fragment were performed for genotyping the PON1 SNPs T-107C and L55M. Serum PON1 activity was measured in a single time point. Patients completed the semi-quantitative food frequency questionnaire and diet composition was estimated.

RESULTS

Genotypic distribution for L55M SNP was 56% for the LL genotype, 32% for LM and 12% for MM; for the PON1 C(-107)T SNP it was 28% for the TT genotype, 41% for CT and 31% for CC. Individuals with C and L alleles had higher serum PON1 activity. Combining the two SNPs, we observed that individuals carrying the LL and CC genotypes had twice the activity of carriers of the TT and MM genotypes. Considering food intake, no significant difference was observed between genotypes and intake levels.

CONCLUSION

PON1 T(-107)C and L55M SNPs exert a strong effect on serum PON1 activity in an additive manner and are more important than diet to predict serum PON1 activity.

Chitosan as possible inhibitory agents and delivery systems in leukemia

Leukemia is a lethal cancer in which white blood cells undergo proliferation and immature white blood cells are seen in the bloodstream. Without diagnosis and management in early stages, this type of cancer can be fatal. Changes in protooncogenic genes and microRNA genes are the most important factors involved in development of leukemia. At present, leukemia risk factors are not accurately identified, but some studies have pointed out factors that predispose to leukemia. Studies show that in the absence of genetic risk factors, leukemia can be prevented by reducing the exposure to risk factors of leukemia, including smoking, exposure to benzene compounds and high-dose radioactive or ionizing radiation. One of the most important treatments for leukemia is chemotherapy which has devastating side effects. Chemotherapy and medications used during treatment do not have a specific effect and destroy healthy cells besides leukemia cells. Despite the suppressing effect of chemotherapy against leukemia, patients undergoing chemotherapy have poor quality of life. So today, researchers are focusing on finding more safe and effective natural compounds and treatments for cancer, especially leukemia. Chitosan is a valuable natural compound that is biocompatible and non-toxic to healthy cells. Anticancer, antibacterial, antifungal and antioxidant effects are examples of chitosan biopolymer properties. The US Food and Drug Administration has approved the use of this compound in medical treatments and the pharmaceutical industry. In this article, we take a look at the latest advances in the use of chitosan in the treatment and improvement of leukemia.

Association between Blood Mercury Concentration and Prevalence of Borderline Hypercholesterolemia among Adolescents: The Korea National Health and Nutrition Examination Survey (KNHANES) 2010-2013 and 2016

There is limited evidence on the association between blood mercury (Hg) concentration and the risk of borderline dyslipidemia in adolescents. Here, we investigated the association between blood Hg concentration and the prevalence of borderline dyslipidemia among Korean adolescents. A total of 1559 participants (806 boys and 753 girls) aged 10–18 years who cross-sectionally enrolled in the Korea National Health and Nutrition Examination Survey (KNHANES) 2010–2013 and 2016 were included in this study. Hg concentrations (µg/L) in whole blood samples were measured. The geometric mean (GM) of the blood Hg concentration was 1.88 µg/L. It showed a 63% higher prevalence of borderline hypercholesterolemia (total cholesterol (TC) 170–199 mg/dL) per unit of natural log-transformed blood Hg concentration in boys (95% CI = 1.10–2.41), but not in girls. When a categorical model was applied, the positive association with the prevalence of borderline hypercholesterolemia was also persistant in boys (OR (95% CI) for 2nd and 3rd tertiles (Hg concentration 1.532–11.761 µg/L) vs. 1st tertile (Hg concentration 0.192–1.531 µg/L): 1.92 (1.19–3.10)), but not in girls. This finding suggests that blood Hg concentration might result in a higher prevalence of borderline hypercholesterolemia among adolescents and more stringent public health actions should be taken for the reduction of Hg exposure to prevent dyslipidemia from early-childhood, despite the need of further study to evaluate a causal relationship between blood Hg concentration and the risk of dyslipidemia.

Fisetin Alleviates Neointimal Hyperplasia via PPARγ/PON2 Antioxidative Pathway in SHR Rat Artery Injury Model

The phenotypic transformation of proliferation and migration in vascular smooth muscle cells (VSMCs) from media to intima is the basic pathology of neointimal hyperplasia after angioplasty in hypertensive patients. Angiotensin II (AngII) stimulates oxidative stress in VSMC, inducing VSMC proliferation and migration, which is a critical factor in both developments of hypertension and angioplasty-induced arterial restenosis. Fisetin, a plant flavonoid polyphenol, has been reported to be antioxidative and potent senolytic. It is unknown whether fisetin would inhibit neointimal hyperplasia. Therefore, we investigated the role of fisetin in neointimal formation in vitro and in vivo. The rat thoracic aortic smooth muscle cells (A10 cells) stimulated by AngII were used as the in vitro neointimal hyperplasia model, where AngII significantly induced the proliferation and migration in A10 cells. We found that fisetin could dose-dependently inhibit the effect of AngII via inducing the expression of an antioxidant, paraoxonase-2 (PON2), whose overexpression could inhibit the proliferation and migration of A10 cells and downexpression by siRNA had the opposite effect. Furthermore, we found the mechanism of fisetin's inducing PON2 expression involved PPARγ. Rosiglitazone, a PPARγ agonist, could increase PON2 expression in A10 cells, while the PPARγ inhibitor prevented the effect of fisetin on PON2. The in vivo neointimal hyperplasia model was established 2 weeks after the carotid artery balloon injury in SHR rats. Administration of fisetin (ip 3 mg/kg daily for 2 weeks) right after the injury significantly increased PON2 expression in the artery, inhibiting ROS production, and efficiently reduced carotid neointimal hyperplasia. These results indicate that fisetin increases the expression of antioxidant PON2 via activation of PPARγ, reducing oxidative stress, inhibiting VSMC proliferation and migration, and alleviates neointimal hyperplasia after intimal injury. PON2 may be a potential therapeutic target to reduce arterial remodeling after angioplasty in hypertensive patients.

Kiwifruit Supplementation Increases the Activity of the Paraoxonase Enzyme and decreases Oxidized Low-Density Lipoprotein in High-Fat Diet Fed Hamsters

Background: It is shown that kiwifruit elevates serum high-density lipoprotein cholesterol (HDL-C) levels and exhibits beneficial effects on human health due to its antioxidant potential. Objectives: This study aimed to investigate the impact of kiwifruit on the activity of the paraoxonase 1 (PON1) enzyme, as a main antioxidant enzyme in HDL functionality, in a high-fat diet (HFD). Methods: To this end, 42 male Syrian hamsters were divided into 6 groups including hamsters receiving a normal diet (the control normal group), a regular diet supplemented with kiwifruit at two concentrations (i.e., 1.86 g/kg and 3.73 g/kg), a HFD comprised of 15% butterfat + 0.05% cholesterol (the control high-fat group), and a HFD supplemented with kiwifruit at two concentrations (i.e., 1.86 and 3.73 g/kg) for 8 weeks. Results: The results showed that supplementation of kiwifruit to the HFD increased the levels of HDL-C and remarkably reduced the concentrations of oxidized low-density lipoprotein (ox-LDL) and malondialdehyde (MDA) compared with the control-HF group. In addition, the paraoxonase activity of PON1 significantly increased in HFD supplemented with kiwifruit (1.86 g/kg), and finally, arylesterase (ARE) activity increased in all treated groups when compared with untreated groups. Conclusion: Our findings suggested that kiwifruit can improve the lipid profile and prevent oxidative stress-induced by lipid peroxidation in hamsters receiving HFD, thus increasing the ARE and paraoxonase activities of PON1.

Effect of acyl and alkyl analogs of platelet-activating factor on inflammatory signaling

Platelet-activating factor (PAF), a bioactive ether phospholipid with significant pro-inflammatory properties, was identified almost half a century ago. Despite extensive study of this autocoid, therapeutic strategies for targeting its signaling components have not been successful, including the recent clinical trials with darapladib, a drug that targets plasma PAF-acetylhydrolase (PAF-AH). We recently provided experimental evidence that the previously unrecognized acyl analog of PAF, which is concomitantly produced along with PAF during biosynthesis, dampens PAF signaling by acting both as a sacrificial substrate for PAF-AH and probably as an endogenous PAF-receptor antagonist/partial agonist. If this is the scenario in vivo, PAF-AH needs to catalyze the selective hydrolysis of alkyl-PAF and not acyl-PAF. Accordingly, different approaches are needed for treating inflammatory diseases in which PAF signaling is implicated. The interplay between acyl-PAF, alkyl-PAF, PAF-AH, and PAF-R is complex, and the outcome of this interplay has not been previously appreciated. In this review, we discuss this interaction based on our recent findings. It is very likely that the relative abundance of acyl and alkyl-PAF and their interactions with PAF-R in the presence of their hydrolyzing enzyme PAF-AH may exert a modulatory effect on PAF signaling during inflammation.

PON-1 haplotype (-108C>T, L55M, and Q192R) modulates the serum levels and activity PONase promoting an atherogenic lipid profile in rheumatoid arthritis patients

INTRODUCTION/OBJECTIVE

Paraoxonase 1 (PON1) promotes antioxidant and antiatherogenic activity related to the hydrolysis of oxidized lipids of low-density lipoproteins. In rheumatoid arthritis (RA) patients, it has been reported that low PON1 activity is related to an impaired lipid profile, increasing cardiovascular risk (CVR). The goal of this study was to analyze the effect of common PON1 polymorphisms and haplotypes on enzymatic activity, PON1 serum levels (PON1s), and lipid parameters related to atherogenic profile in RA patients.

METHODS

A cross-sectional study was carried out on 250 Mexican patients with RA. The lipid profile was determined by colorimetric tests. The PON1 activity (CMPAase) was measured by spectrophotometry. The levels of PON1s were determined by ELISA, and the polymorphisms in the PON-1 gene (-108C>T, L55M, and Q192R) were genotyped by the PCR-RFLP method. The haplotypes were estimated and statistical analysis was performed.

RESULTS

The median of the CMPAase activity and PON1 levels was 13.91 U/mL and 24.75 ng/mL, respectively. The CMPAase activity was significantly lower in carriers of -108TT and 192QQ genotypes (β = - 4.09, P = 0.001 and β = - 3.73, P = 0.002, respectively); moreover, the PON1 levels were lower in 192Q allele carriers (P < 0.01). The TLQ haplotype was associated with CMPAase activity < 13.91 U/mL (OR = 2.29, P < 0.001), as well as with levels of PON1s < 24.75 ng/mL (OR = 1.65, P = 0.017). In this study, the CMPAase activity (< 13.91 U/mL) showed a positive association with lower levels of high-density lipoprotein cholesterol (HDL-c; < 40/50 mg/dL), and with a triglycerides/HDL-c ratio > 3%, and a total cholesterol/HDL-c ratio > 4.5/5%, all representatives of an atherogenic risk lipid profile.

CONCLUSIONS

PON1 polymorphisms modulate the CMPAase activity and PON1 levels in Mexican patients with RA. The CMPAase activity < 13.91 U/mL is associated with an atherogenic lipid profile, independently of inflammation markers and treatment with anti-rheumatic drugs. Key Points •The haplotype TLQ is a marker for low PONase activity in rheumatoid arthritis. •The haplotype TLQ is a marker for low PON1 serum levels in rheumatoid arthritis. •The enzymatic PON1 activity represents the best marker for an atherogenic lipid profile in rheumatoid arthritis, in comparison with PON1 levels. •The haplotype TLQ is a marker of low PON1 activity, levels of PON1s, and atherogenic lipid profile, independent of treatment therapy in rheumatoid arthritis.

A comparative pharmacogenomic analysis of three classic TCM prescriptions for coronary heart disease based on molecular network modeling

Traditional Chinese medicine (TCM) has evolved over several thousands of years, which has been shown to be efficacious in the treatment of ischemic heart disease. Three classical TCM prescriptions, namely Xuefu Zhuyu Decoction, Zhishi Xiebai Guizhi Decoction, and Gualou Xiebai Banxia Decoction, have been extensively used in the treatment of coronary heart disease (CHD). Based on molecular network modeling, we performed a comparative pharmacogenomic analysis to systematically determine the drug-targeting spectrum of the three prescriptions at molecular level. Wide-area target molecules of CHD were covered, which was a common feature of the three decoctions, demonstrating their therapeutic functions. Meanwhile, collective signaling involved metabolic/pro-metabolic pathways, driving and transferring pathways, neuropsychiatric pathways, and exocrine or endocrine pathways. These organized pharmacological disturbance was mainly focused on almost all stages of CHD intervention, such as anti-atherosclerosis, lipid metabolism, inflammation, vascular wall function, foam cells formation, platelets aggregation, thrombosis, arrhythmia, and ischemia-reperfusion injury. In addition, heterogeneity analysis of the global pharmacological molecular spectrum revealed that signaling crosstalk, cascade convergence, and key targets were tendentious among the three decoctions. After all, it is unadvisable to rank the findings on targeting advantages of the three decoctions. Comparative pharmacological evidence may provide an appropriate decoction scheme for individualized intervention of CHD.

Gene therapy delivering a paraoxonase 1 variant offers long-term prophylactic protection against nerve agents in mice

Chemical warfare nerve agents are organophosphorus chemical compounds that induce cholinergic crisis, leaving little or no time for medical intervention to prevent death. The current chemical treatment regimen may prevent death but does not prevent postexposure complications such as brain damage and permanent behavioral abnormalities. In the present study, we have demonstrated an adeno-associated virus 8 (AAV8)-mediated paraoxonase 1 variant IF-11 (PON1-IF11) gene therapy that offers asymptomatic prophylactic protection to mice against multiple lethal doses of G-type chemical warfare nerve agents, namely, tabun, sarin, cyclosarin, and soman, for up to 5 months in mice. A single injection of liver-specific adeno-associated viral particles loaded with PON1-IF11 gene resulted in expression and secretion of recombinant PON1-IF11 in milligram quantities, which has the catalytic power to break down G-type chemical warfare nerve agents into biologically inactive products in vitro and in vivo in rodents. Mice containing milligram concentrations of recombinant PON1-IF11 in their blood displayed no clinical signs of toxicity, as judged by their hematological parameters and serum chemistry profiles. Our study unfolds avenues to develop a one-time application of gene therapy to express a near-natural and circulating therapeutic PON1-IF11 protein that can potentially protect humans against G-type chemical warfare nerve agents for several weeks to months.

Effects of PON1 Gene Promoter DNA Methylation and Genetic Variations on the Clinical Outcomes of Dual Antiplatelet Therapy for Patients Undergoing Percutaneous Coronary Intervention

INTRODUCTION AND OBJECTIVE

The relationship between either paraoxonase 1 (PON1) gene promoter DNA methylation or genetic variations and bleeding or major adverse cardiac events after dual antiplatelet therapy has been incompletely characterized. We aimed to systematically investigate the role of genetic variations and DNA methylation of the PON1 CpG island promoter on the clinical outcomes of dual antiplatelet therapy for patients with coronary artery disease (CAD) who underwent percutaneous coronary intervention (PCI).

METHODS

This study included 653 patients with CAD undergoing PCI and receiving dual antiplatelet therapy. Genomic DNAs were isolated from whole blood and were genotyped for the three single nucleotide polymorphisms (SNPs) of the PON1 gene. The DNA methylation levels in the PON1 promoter region were determined by bisulfite sequencing or pyrosequencing at five CpG sites (positions -142, -161, -163, -170, and -184 from the transcription start site). Clopidogrel and its metabolites in plasma were examined using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), and platelet function analysis was performed using the VerifyNow assay.

RESULTS

Statistically significant associations between methylation levels at five PON1 CpG sites and bleeding were observed: -184 [odds ratio (OR) 0.98, 95% confidence interval (CI) 0.96-1.00, p = 0.028]; -170 (OR 0.99, 95% CI 0.97-1.00, p = 0.048); -163 (OR 0.98, 95% CI 0.96-1.00, p = 0.029); -161 (OR 0.98, 95% CI 0.97-1.00, p = 0.026); and -142 (OR 0.98, 95% CI 0.97-1.00, p = 0.042) at a false discovery rate of <5%. Statistical analysis also revealed that aspirin reaction units (ARUs) were significantly associated with PON1 methylation level at CpG site -163 (p = 0.0342). The ARUs of patients with the PON1 126 CC genotype was 527 ± 94, which was higher than the ARUs (473 ± 89) of patients with the 126 CG genotype (p = 0.0163). Multivariate logistic regression analysis indicated that the PON1 methylation level at CpG site -161 (OR 0.95, 95% CI 0.92-0.98, p = 0.002) and the use of angiotensin-converting enzyme inhibitors (OR 0.48, 95% CI 0.26-0.89, p = 0.021) were associated with a decreased risk of bleeding events.

CONCLUSIONS

Hypomethylation of CpGs in the PON1 promoter may be a weak, albeit statistically significant, risk factor of bleeding after dual antiplatelet therapy. Further large-scale studies are needed to verify our results.

The impact of aerobic and isometric exercise on different measures of dysfunctional high-density lipoprotein in patients with hypertension

BACKGROUND

Exercise training increases high-density lipoprotein (HDL) cholesterol, but its effect on HDL function is unclear. In hypertensives, exercise improves endothelial dysfunction, which is related to HDL function. In the present study, we assess for the first time the effects of different exercise modalities on two cell-free assays of HDL function.

DESIGN

The study was conducted as a prospective randomized controlled trial in 75 hypertensive patients.

METHODS

Patients were randomized in three groups: (a) handgrip isometric training five times weekly; (b) placebo-handgrip; and (c) aerobic exercise training at least three times per week. HDL function was assessed in serum samples at baseline and after 12 weeks of training by two independent assays that determine the proinflammatory phenotype (haptoglobin content) of a specific amount of HDL (Haptoglobin-HDL [HPHDL]) and oxidized HDL (HDLox) as a measure of reduced antioxidant function of HDL. HDL function measures were normalized by the measures of a pooled control of sera from healthy participants and by HDL-C levels (normalized ratio, no units).

RESULTS

Aerobic exercise led to significant reduction of the HDLox from 0.99 ± 0.27 to 0.90 ± 0.29 (no units, p = 0.03). The HPHDL did not change in any training group. Changes of HDLox correlated with reduction of the systolic blood pressure only after aerobic exercise (R = 0.64, p = 0.03).

CONCLUSIONS

Aerobic but not isometric exercise improves the antioxidant function of HDL in patients with hypertension. This improvement correlates positively with reductions of blood pressure.

Decreased serum PON1 arylesterase activity in familial hypercholesterolemia patients with a mutated LDLR gene

Paraoxonase 1 (PON1) is a serum enzyme associated with high density lipoprotein (HDL) regulation through its paraoxonase and arylesterase activity. PON1 inhibits the oxidation of HDL and low density lipoprotein (LDL), and is involved in the pathogenesis of a variety of diseases including atherosclerosis. Conversely, mutations in the low density lipoprotein receptor (LDLR) result in failure of receptor mediated endocytosis of LDL leading to its elevated plasma levels and onset of familial hypercholesterolemia (FH). In the current study we investigated the role of PON1 polymorphisms rs662; c.575A > G (p.Gln192Arg) and rs854560; c.163T > A (p.Leu55Met) in a large family having FH patients harboring a functional mutation in LDLR. Genotypes were revealed by RFLP, followed by confirmation through Sanger sequencing. PON1 activity was measure by spectrophotometry. Our results show significantly reduced serum paraoxonase and arylesterase activities in FH patients compared with the healthy individuals of the family (p < 0.05). PON1 QQ192 genotype showed a significantly higher association with FH (p=0.0002). PON1 Q192 isoform was associated with reduced serum paraoxonase activity by in silico analysis and PON1 R192 exhibited higher serum paraoxonase and arylesterase activity than the other polymorphs. Our results highlight that the combination of LDLR mutations and PON1 MMQQ genotypes may lead to severe cardiac events.

Downregulation of human paraoxonase 1 (PON1) by organophosphate pesticides in HepG2 cells

Paraoxonase 1 (PON1) is a calcium-dependent esterase synthesized primarily in the liver and secreted into the plasma where it is associated with high-density lipoproteins (HDL). PON1 hydrolyzes and detoxifies some toxic metabolites of organophosphorus compounds (OPs) such as methyl parathion and chlorpyrifos. Thus, PON1 activity and expression levels are important for determining susceptibility against OPs poisoning. Some studies have demonstrated that OPs can modulate gene expression through interactions with nuclear receptors. In this study, we evaluated the effects of methyl parathion and chlorpyrifos on the modulation of PON1 in Human Hepatocellular Carcinoma (HepG2) cells by real-time PCR, PON1 activity assay, and western blot. The results showed that the treatments with methyl parathion and chlorpyrifos decreased PON1 mRNA and immunoreactive protein and increased inflammatory cytokines in HepG2 cells. The effects of methyl parathion and chlorpyrifos on the downregulation of PON1 gene expression in HepG2 cells may provide evidence of OPs cytotoxicity related to oxidative stress and an inflammatory response. A decrease in the expression of the PON1 gene may increase the susceptibility to OPs intoxication and the risk of diseases related to inflammation and oxidative stress. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 490-500, 2017.

Toenail mercury and dyslipidemia: Interaction with selenium

BACKGROUND

Although compelling evidences from in vivo and in vitro studies exist, limited studies have examined the association between chronic mercury exposure and dyslipidemia. Particularly, data are sparse regarding the influence of selenium on this association of mercury with dyslipidemia in humans.

PURPOSE

The purpose of the current study was to examine the associations of toenail mercury with dyslipidemia and its components, and to examine whether selenium in toenails modifies these associations.

METHODS

We performed cross-sectional analyses using baseline data from a cohort in the Yeungnam area in South Korea, including 232 men and 269 women. Toenail mercury and selenium concentrations were quantified using neutron activation analysis, and fasting serum lipid measurements were obtained through the medical examination. Odds ratios of the prevalent hypercholesterolemia, hyper-LDL-cholesterolemia, hypo-HDL-cholesterolemia, hypertriglyceridemia, and dyslipidemia in correlation with mercury levels were calculated using multivariable logistic regression.

RESULTS

The mean levels of toenail mercury were 0.47μg/g for men and 0.34μg/g for women. After adjustment for multiple confounding variables, participants in the highest tertile of toenail mercury levels had 4.08 (95% CI 1.09-15.32, p for trend=0.02) times higher risk of hyper-LDL-cholesterolemia, and 2.24 (95% CI 1.15-4.37, p for trend=0.004) times higher risk of dyslipidemia than those in the lowest tertile. Selenium is a significant effect-modifier for these associations; the highest tertile of toenail mercury were significantly associated with a higher risk of hypercholesterolemia (OR 5.25, 95% CI 1.04-26.38) and dyslipidemia (OR 2.98, 95% CI 1.16-7.66) compared to the lowest tertile at toenail selenium levels ≤0.685μg/g, while these associations became weak and non-significant, showing OR 0.98 and 95% CI 0.25-3.80 for hypercholesterolemia and OR 1.99 and 95% CI 0.73-5.45 for dyslipidemia at toenail selenium levels >0.685μg/g.

DISCUSSION

We confirmed the beneficial effects of selenium against the harmful effects of mercury in humans with relatively high consumption of fish. Our finding has important implications in making dietary recommendations regarding optimal levels of fish and selenium intakes. Further studies are warranted to determine the appropriate level of fish consumption, considering both methylmercury and selenium exposure, in a larger prospective cohort or RCT.

Paraoxonase and atherosclerosis-related cardiovascular diseases

In humans, three paraoxonase (PON1, PON2, and PON3) genes are clustered on chromosome 7 at a locus that spans a distance around 170 kb. These genes are highly homologous to each other and have a similar protein structural organization. PON2 is the intracellular enzyme, which is expressed in many tissues and organs, while two other members of PON gene family are produced by liver and associate with high density lipoprotein (HDL). The lactonase activity is the ancestral. Besides lactones and organic phosphates, PONs can hydrolyze and therefore detoxify oxidized low density lipoprotein and homocysteine thiolactone, i.e. two cytotoxic compounds with a strong proatherogenic action. Indeed, PONs possess numerous atheroprotective properties, which include antioxidant activity, anti-inflammatory action, preserving HDL function, stimulation of cholesterol efflux, anti-apoptosis, anti-thrombosis, and anti-adhesion. PON genetic polymorphisms contribute to susceptibility/protection from atherosclerosis-related diseases. The bright antiatherogenic activity of the PON cluster makes it a promising target for the development of new therapeutic strategies.

Assessing the stoichiometric efficacy of mammalian expressed paraoxonase-1 variant I-F11 to afford protection against G-type nerve agents

We evaluated the ability of evolved paraoxonase-1 (PON1) to afford broad spectrum protection against G-type nerve agents when produced in mammalian cells via an adenovirus expression system. The PON1 variants G3C9, VII-D11, I-F11, VII-D2 and II-G1 were screened in vitro for their ability to hydrolyze G-agents, as well as for their preference towards hydrolysis of the more toxic P(-) isomer. I-F11, with catalytic efficiencies of (1.1 ± 0.1) × 10⁶ M^-1 min^-1, (2.5 ± 0.1) × 10⁶ M^-1 min^-1, (2.3 ± 0.5) × 10⁷ M^-1 min^-1and (9.2 ± 0.1) × 10⁶ M^-1 min^-1 against tabun (GA), sarin (GB), soman (GD) and cyclosarin (GF), respectively, was found to be a leading candidate for further evaluation. To demonstrate the broad spectrum efficacy of I-F11 against G-agents, a sequential 5 × LD₅₀ dose of GD, GF, GB and GA was administered to ten mice expressing I-F11 on days 3, 4, 5 and 6 following virus injection, respectively. At the conclusion of the experiment, 80% of the animals survived exposure to all four G-agents. Using the concept of stoichiometric efficacy, we determined that I-F11 affords protection from lethality against an administered dose of 10, 15, 90 and 80 molar equivalents of GA, GB, GD and GF, respectively, relative to the molar equivalents of I-F11 in circulation. It also appears that I-F11 can associate with high density lipoprotein in circulation, suggesting that I-F11 retained this function of native PON1. This combination of attractive attributes demonstrates that I-F11 is an attractive candidate for development as a broad-therapeutic against G-type nerve agent exposure.

Comparison of serum paraoxonase and arylesterase activities between iron deficiency anemia patients and chronic kidney disease patients with anemia

OBJECTIVE

Altered paraoxonase (PON) and arylesterase (ARE) activities have been shown in anemic chronic kidney disease (CKD) patients and in iron deficiency anemia (IDA) patients. Whether accompanying anemia alone is responsible for this diminished PON and ARE activities in CKD patients or an additive factor for this is not well studied. Therefore, we tried to clarify this issue here.

METHODS

A total of 82 subjects that consisted of 19 patients with IDA (group 1), 23 anemic CKD patients (group 2), and 40 age and sex matched healthy subjects (group 3) were enrolled. Carotid intima media thickness (CIMT), serum total thiol (-SH), PON, and ARE activities of the participants were analyzed.

RESULTS

Group 2 patients had significantly lowest serum levels of Total -SH, PON and ARE. Further comparison showed that total -SH, PON and ARE levels were lower in group 1 than group 3 (p = 0.0001 in both). Regarding comparison of group 1 and 2, only serum ARE levels were significantly lower in group 2 (p = 0.001). PON activity was not different between group 1 and group 2 whereas ARE activity was lower in group 2 than groups 1 and 3. In addition, correlation analysis showed that CIMT was negatively correlated with PON and ARE.

CONCLUSIONS

This markedly decreased ARE activity in CKD patients, which could not be explained by the anemia alone, may have a role in the pathogenesis of increased atherosclerosis in such patients. Still further studies are needed to certain this.

Atherosclerotic process in taxi drivers occupationally exposed to air pollution and co-morbidities

Consistent evidence has indicated that the exposure to environmental air pollution increases the risk of cardiovascular disease. This study aimed to evaluate the possible effects of occupational exposure to air pollution, especially to polycyclic aromatic hydrocarbons (PAHs), and the influence of co-morbidities on the atherosclerotic process and inflammation. For that, biomarkers of exposure such as 1-hydroxypyrene urinary, oxidative damage and markers of cardiovascular risk were determined in plasma, serum and blood. In addition, inflammation models such as carotid intima-media thickness and serum inflammatory cytokines were analyzed in 58 taxi drivers with and without co-morbidity. The results demonstrated that considering only taxi drivers without co-morbidities, 15% presented carotid intima-media thickness above reference values. For the first time it has been demonstrated that urinary 1-hydroxypyrene levels were associated with carotid intima-media thickness and with serum homocysteine levels. The multiple linear regression analysis showed that several factors may contribute to the increased carotid intima-media thickness, among which age, interleukin-6, fibrinogen and exposure to PAHs stand out. In summary, our results suggest that chronic occupational exposure to atmospheric pollution could be an additional contributor to the atherogenesis process, leading to impaired vascular health. Moreover, carotid intima-media thickness, serum homocysteine levels, fibrinogen and the total cholesterol/HDL-c ratio could be suggested as preventive measures to monitor drivers' health.

Investigation of evolved paraoxonase-1 variants for prevention of organophosphorous pesticide compound intoxication

We investigated the ability of the engineered paraoxonase-1 variants G3C9, VII-D11, I-F11, and VII-D2 to afford protection against paraoxon intoxication. Paraoxon is the toxic metabolite of parathion, a common pesticide still in use in many developing countries. An in vitro investigation showed that VII-D11 is the most efficient variant at hydrolyzing paraoxon with a kcat/Km of 2.1 × 10(6) M(-1) min(-1) and 1.6 × 10(6) M(-1) min(-1) for the enzyme expressed via adenovirus infection of 293A cells and mice, respectively. Compared with the G3C9 parent scaffold, VII-D11 is 15- to 20-fold more efficacious at hydrolyzing paraoxon. Coinciding with these results, mice expressing VII-D11 in their blood survived and showed no symptoms against a cumulative 6.3 × LD50 dose of paraoxon, whereas mice expressing G3C9 experienced tremors and only 50% survival. We then determined whether VII-D11 can offer protection against paraoxon when present at substoichiometric concentrations. Mice containing varying concentrations of VII-D11 in their blood (0.2-4.1 mg/ml) were challenged with doses of paraoxon at fixed stoichiometric ratios that constitute up to a 10-fold molar excess of paraoxon to enzyme (1.4-27 × LD50 doses) and were assessed for tremors and mortality. Mice were afforded complete asymptomatic protection below a paraoxon-to-enzyme ratio of 8:1, whereas higher ratios produced tremors and/or mortality. VII-D11 in mouse blood coeluted with high-density lipoprotein, suggesting an association between the two entities. Collectively, these results demonstrate that VII-D11 is a promising candidate for development as a prophylactic catalytic bioscavenger against organophosphorous pesticide toxicity.

Regulatory regions of the paraoxonase 1 (PON1) gene are associated with neovascular age-related macular degeneration (AMD)

Physiological stress response and oxidative damage are factors for aging processes and, as such, are thought to contribute to neovascular age-related macular degeneration (AMD). Paraoxonase 1 (PON1) is an enzyme that plays an important role in oxidative stress and aging. We investigated association of DNA sequence variants (SNP) within the upstream regulatory region of the PON1 gene with neovascular AMD in 305 patients and 288 controls. Four of the seven tested SNPs (rs705379, rs705381, rs854573, and rs757158) were more frequently found in AMD patients compared to controls (P = 0.0099, 0.0295, 0.0121, and 0.0256, respectively), and all but one (SNP rs757158) are in linkage disequilibrium. Furthermore, haplotype TGGCCTC conferred protection (odds ratio (OR) = 0.76, (CI) = 0.60-0.97) as it was more frequently found in control individuals, while haplotype CGATGCT increased the risk (OR = 1.55, CI = 1.09-2.21) for AMD. These results were also reflected when haplotypes for the untranscribed and the 5'untranslated regions (5'UTR) were analyzed separately. To assess haplotype correlation with levels of gene expression, the three SNPs within the 5'UTR were tested in a luciferase reporter assay. In retinal pigment epithelium-derived ARPE19 cells, we were able to measure significant differences in reporter levels, while this was not observed in kidney-derived HEK293 cells. The presence of the risk allele A (SNP rs705381) caused an increase in luciferase activity of approximately twofold. Our data support the view that inflammatory reactions mediated through anti-oxidative activity may be relevant to neovascular age-related macular degeneration.

A functional polymorphism of PON1 interferes with microRNA binding to increase the risk of ischemic stroke and carotid atherosclerosis

OBJECTIVE

Single nucleotide polymorphisms (SNPs) located at microRNA (miRNA) binding sites (miR-SNPs) can affect the expression of genes. This study aimed to identify the miR-SNPs associated with atherosclerosis and stroke.

METHODS

Patients with ischemic stroke (n = 657) and stroke- and myocardial infarction-free volunteers (n = 1571) were enrolled. The carotid intima-media thickness (IMT) was measured in the control participants. Seventy-nine stroke susceptibility genes were initially selected and 13 genes were predicted to have miR-SNPs at their 3' untranslated regions (3'UTR). The miRNA arrays were used to further identify potential miR-SNPs. The miR-SNP rs3735590 at the paraoxonase 1 (PON1) gene was finally selected and its associations with stroke and carotid IMT were evaluated. The 3'UTR reporter and SNP functional assays were then performed to validate the results.

RESULTS

Compared with CC genotype, patients with CT or TT genotype at rs3735590 had lower risk of ischemic stroke (OR = 0.72, p = 0.036; OR = 0.83, p = 0.077, respectively). Among the healthy participants, the CT or TT genotype was associated with thinner IMT in the internal carotid arteries in comparison with CC genotype (β = -0.76, p = 0.003; β = -0.022, p = 0.452, respectively). Our findings suggested that the minor allele T had a protective effect on atherosclerosis. Results from 3'UTR reporter assays showed that PON1 is a direct target gene of miR-616. In plasmid constructs carrying the risk allele C at rs3735590, miR-616 inhibited the genetic expression of PON1. However, substitution of C by T at rs3735590 reduced the miR-616 binding affinity, leading to overexpression of the PON1 gene.

CONCLUSION

Our study is the first to show that the miR-SNP at PON1 could affect genetic expression and is associated with an elevated risk for ischemic stroke and subclinical atherosclerosis.

Paraoxonase 1 gene polymorphism does not affect clopidogrel response variability but is associated with clinical outcome after PCI

Background

Paraoxonase (PON) is a high-density-lipoprotein (HDL) associated enzyme with antioxidative and anti-atherogenic property. Its function is associated with coronary artery disease and its activity genetically controlled. We evaluated whether genetic variation of PON-1 is associated with clinical outcome in a large cohort of Korean patients with drug-eluting stents implantation.

Methods

A total of 1676 patients with drug-eluting stent implantation were enrolled in the prospective CROSS-VERIFY cohort from June 2006 to June 2010. We genotyped the PON1-Q192R gene, measured clopidogrel on-treatment platelet reactivity (OPR), and analyzed lipid profiles. The primary endpoint was the composite of cardiac death, myocardial infarction, and stent thrombosis at 12 months.

Results

PON-1 genotyping data were available in 1336 patients. Since the Q-allele is associated with decreased PON-activity, we analyzed the outcome between patients with QQ/QR (815 patients, 61%) and those with RR-genotype (521 patients, 39%). After adjustment for common cardiac risk factors, the QQ/QR-genotype was an independent predictor of the primary thrombotic endpoint with an 11-fold increased risk (HR 11.6, 95% CI: 1.55–87.0), but not repeat revascularization (HR 1.12, 95% CI: 0.78–1.61). The QQ/QR-genotype was not associated with OPR (QQ/QR: 231±86 PRU vs. RR 236±82 PRU, p = 0.342) but higher small-dense LDL levels (1.20±0.12 mg/dL vs. 0.76±0.15 mg/dL, p = 0.027). The increased risk of thrombotic outcomes was more profound in acute coronary syndrome (ACS) patients compared with non-ACS patients.

Conclusion

PON1 Q-allele is an independent predictor of worse cardiovascular outcome independent of platelet function and is associated with significantly higher levels of small dense LDL-C.

The Past and Present of Paraoxonase Enzyme: Its Role in the Cardiovascular System and Some Diseases

Although paraoxonase is synthesized in many tissues including the heart, colon, kidneys, lungs, small intestines and brain, its major locus of synthesis is the liver. PON1 is in close association with apolipoproteins and protects LDL against oxidation. It was reported that PON1 quantities dropped to 40 times lower than normal in cardiovascular diseases and diseases like diabetes, ulcerative colitis, Crohn's disease, chronic renal failure, SLE, Behcet's disease, cancer, hepatitis B, obesity, metabolic syndrome, Alzheimer's and dementia. It is speculated that the concerning decline in serum PON1 amount results from single nucleotide polymorphism in the coding (Q192R, L55M) and promoter (T-108C) sites of the PON1 gene. Additionally, circulating amounts of PON1 are affected by vitamins, antioxidants, fatty acids, dietary factors, drugs, age and lifestyle. This collection attempts to review and examine the past and present studies of paraoxonase and its relation with the cardiovascular system and some relevant diseases.

The human paraoxonase gene cluster as a target in the treatment of atherosclerosis

The paraoxonase (PON) gene cluster contains three adjacent gene members, PON1, PON2, and PON3. Originating from the same fungus lactonase precursor, all of the three PON genes share high sequence identity and a similar β propeller protein structure. PON1 and PON3 are primarily expressed in the liver and secreted into the serum upon expression, whereas PON2 is ubiquitously expressed and remains inside the cell. Each PON member has high catalytic activity toward corresponding artificial organophosphate, and all exhibit activities to lactones. Therefore, all three members of the family are regarded as lactonases. Under physiological conditions, they act to degrade metabolites of polyunsaturated fatty acids and homocysteine (Hcy) thiolactone, among other compounds. By detoxifying both oxidized low-density lipoprotein and Hcy thiolactone, PONs protect against atherosclerosis and coronary artery diseases, as has been illustrated by many types of in vitro and in vivo experimental evidence. Clinical observations focusing on gene polymorphisms also indicate that PON1, PON2, and PON3 are protective against coronary artery disease. Many other conditions, such as diabetes, metabolic syndrome, and aging, have been shown to relate to PONs. The abundance and/or activity of PONs can be regulated by lipoproteins and their metabolites, biological macromolecules, pharmacological treatments, dietary factors, and lifestyle. In conclusion, both previous results and ongoing studies provide evidence, making the PON cluster a prospective target for the treatment of atherosclerosis.

Paraoxonase 1 in chronic kidney failure

In this review we summarize the findings from the literature and our own laboratory on the decreased PON1 activity in renal failure, the mechanisms proposed and the effect of interventions. In addition to profound alterations in lipoproteins, reduced serum PON1 activity has been clearly established in the past decade and could contribute to accelerated development of atherosclerosis in ESRD and in HD. PON1 lactonase activity is lower in ESRD patients. Hemodialysis partially restores PON1 lactonase and the other activities. PON1 activity recovery after dialysis suggests that uremic toxins may play a mechanistic role in PON1 inactivation. Lower PON1 activity in CRF patients is associated with low thiol concentration, high CRP, and is beneficially enhanced with vitamin C and flavonoids. Changes in HDL subclasses, namely lower HDL₃ in these patients may also play a role in PON1 lower activity. Future research should focus on: (1) mechanistic studies on causes for low PON1 activity and mass; (2) prospective studies focusing on whether there is an added predictive value in measuring PON1 activity (and PON1 activity in HDL₃) in this patient population; (3) intervention studies attempting to increase PON1 activity.

Relation between methylmercury exposure and plasma paraoxonase activity in inuit adults from Nunavik

BACKGROUND

Methylmercury (MeHg) exposure has been linked to an increased risk of coronary heart disease (CHD). Paraoxonase 1 (PON1), an enzyme located in the high-density-lipoprotein (HDL) fraction of blood lipids, may protect against CHD by metabolizing toxic oxidized lipids associated with low-density liproprotein and HDL. MeHg has been shown to inhibit PON1 activity in vitro, but this effect has not been studied in human populations.

OBJECTIVES

This study was conducted to determine whether blood mercury levels are linked to decreased plasma PON1 activities in Inuit people who are highly exposed to MeHg through their seafood-based diet.

METHODS

We measured plasma PON1 activity using a fluorogenic substrate and blood concentrations of mercury and selenium by inductively coupled plasma mass spectrometry in 896 Inuit adults. Sociodemographic, anthropometric, clinical, dietary, and lifestyle variables as well as PON1 gene variants (rs705379, rs662, rs854560) were considered as possible confounders or modifiers of the mercury-PON1 relation in multivariate analyses.

RESULTS

In a multiple regression model adjusted for age, HDL cholesterol levels, omega-3 fatty acid content of erythrocyte membranes, and PON1 variants, blood mercury concentrations were inversely associated with PON1 activities [β-coefficient = -0.063; 95% confidence interval (CI), -0.091 to -0.035; p < 0.001], whereas blood selenium concentrations were positively associated with PON1 activities (β-coefficient = 0.067; 95% CI, 0.045-0.088; p < 0.001). We found no interaction between blood mercury levels and PON1 genotypes.

CONCLUSIONS

Our results suggest that MeHg exposure exerts an inhibitory effect on PON1 activity, which seems to be offset by selenium intake.

Synergism between paraoxonase Arg 192 and the angiotensin converting enzyme D allele is associated with severity of coronary artery disease

We have previously shown that angiotensin-converting enzyme (ACE) gene D allele is an independent risk factor for early onset coronary artery disease (CAD). Little is known about the concomitant presence of the ACE gene D allele and paraoxonase (PON1) codon 192 arginine (Arg) on the severity of CAD. Regarding the high rate of CAD among Iranians the aim of present study was to examine the hypothesis of synergistic effects between ACE-D and PON1-Arg alleles on predisposition and the severity of CAD in our population. The PON1 192 and ACE insertion/deletion (I/D) genotypes were detected by PCR-RFLP and PCR, respectively in 414 individuals undergoing their first coronary angiography. Patients were placed into one of two groups: CAD and control without CAD or diabetes. We mentioned the synergistic effects of both genes and not ACE gene alone is a risk factor for CAD. We found that PON1 Arg 192 and ACE D allele act synergistically to increase the risk of CAD (OR 1.3, P = 0.044). Our results showed a significant correlation between the possession of both PON1 192 Arg and the ACE D allele and the extent of CAD in CAD patients and CAD subjects without diabetes, represented by the increased frequency of three-vessel disease with OR 2.7, P = 0.046; χ(2) = 4, P = 0.046 and OR 2.4, P = 0.051; χ(2) = 3.8, P = 0.051, respectively. We found that PON1 Arg 192 and ACE D alleles act synergistically to increase the risk of CAD in CAD patients and CAD subjects without diabetes from west of Iran, who have high frequency of three-vessel disease. Our data suggest that PON1 192 Arg and the ACE D allele in combination with each other can be important independent risk factor for severity of CAD in patients carrying both PON1 192 Arg and the ACE D allele in a west population of Iran.

Effect of atorvastatin therapy on oxidant-antioxidant status and atherosclerotic plaque formation

Background:

The aim of this study was to determine the oxidant–antioxidant status and lipid peroxidation products, as well as paraoxonase and atherosclerotic plaque formation, in a hypercholesterolemic atherosclerosis rabbit model to investigate the effects of atorvastatin in the atherosclerotic process.

Methods:

Forty male New Zealand rabbits were divided into four groups, ie, a control group receiving standard pellets, a group receiving atorvastatin therapy, a hypercholesterolemic group receiving an atherogenic diet, and a group receiving both an atherogenic diet and atorvastatin.

Results:

The atherogenic diet increased the levels of low-density lipoprotein (LDL) thiobarbituric acid reactive substances (1.84 vs 3.79 nmol/mg protein) and LDL-conjugated diene (147 vs 318 μmol/mg protein) after induction of oxidation by Cu²⁺, despite an increase of superoxide dismutase activity. Treatment with atorvastatin limited LDL oxidation significantly (LDL thiobarbituric acid reactive substances 2.19 nmol/mg protein, LDL-conjugated diene 222 μmol/mg protein). Paraoxonase, which prevents LDL oxidation and inactivates LDL-derived oxidized phospholipids, showed a pronounced decrease in the group receiving the atherogenic diet (110 U/L to 28 U/L), and atorvastatin treatment increased paraoxonase activity. Histological examination of arcus aorta tissues from the hypercholesterolemic group showed abundant plaque formation surrounding and obstructing the lumen, whereas treatment with atorvastatin prevented or limited plaque formation, keeping the plaque thin and localized.

Conclusion:

Atorvastatin has dramatic antiatherosclerotic effects, part of which seems to be due to the antioxidant features of the parent drug and/or its metabolites, favoring inhibition of LDL oxidation.

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.

Cross-sectional study of risk factors for atherosclerosis in the Azorean population

BACKGROUND

Atherosclerosis-a major cause of vascular disease, including ischemic heart disease (IHD), is a pathology that has a two-fold higher mortality rate in the Azorean Islands compared to mainland Portugal.

AIM

This cross-sectional study investigated the role of genetic variation in the prevalence of atherosclerosis in this population.

SUBJECTS AND METHODS

A total of 305 individuals were characterized for polymorphisms in eight susceptibility genes for atherosclerosis: ACE, PAI1, NOS3, LTA, FGB, ITGB3, PON1 and APOE. Data were analysed with respect to phenotypic characteristics such as blood pressure, lipid profile, life-style risk factors and familial history of myocardial infarction.

RESULTS

In the total sample, frequencies for hypercholestrolemic, hypertensive and obese individuals were 63.6%, 39.3% and 23.3%, respectively. The genetic profile was similar to that observed in other European populations, namely in mainland Portugal. No over-representation of risk alleles was evidenced in this sample.

CONCLUSIONS

One has to consider the possibility of an important non-genetic influence on the high cholesterolemia present in the Azorean population. Since diet is the most important life-style risk factor for dyslipidemia, studies aiming to evaluate the dietary characteristics of this population and its impact on serum lipid levels will be of major importance.

Paraoxonase 1 192 and 55 polymorphisms in osteosarcoma

Paraoxonase is an HDL-associated enzyme that plays a preventive role against oxidative stres. Previous studies suggested that involved an amino acid substitution at position 192 gives rise to two alloenzymes with a low activity (Q allele) and a high activity (R allele) towards paraoxon. There also exists a second polymorphism of the human PON1 gene affecting amino acid 55, giving rise to a leucine (L-allele) substitution for methionine (M-allele). PON1 gene polymorphisms were studied in 50 patients with osteosarcoma and 50 healthy controls. Paraoxonase genotypes were determined by PCR-RFLP. We found a reduction in the frequency of PON1 192 R allele in patients (P=0.015). Besides, PON1 192 wild type QQ genotype (P=0.015) and PON1 55 wild type L allele (P=0.001) were higher in patients compared to healthy controls. PON1 192 QQ genotype was associated with osteosarcoma in multivariate logistic regression analysis. Our findings have suggested that PON1 192 wild type genotypes may be associated with a risk of developing osteosarcoma.

Expanded network of inflammatory markers of atherogenesis: where are we now?

Inflammatory biomarkers play a pivotal role in atherosclerotic lesions. The plasma levels of these markers are predictive of adverse outcomes such as myocardial infarction and cardiovascular death. The immune system is involved at all stages of atherogenesis via activation of monocytes/macrophages and T lymphocytes. Circulating proinflammatory cytokines and chemokines produced by these cells interact with specific receptors on various cells and activate specific signaling pathways, leading to inflammation-induced atherosclerotic lesions. Recent studies have focused on predictive value of inflammatory biomarkers such as C-reactive protein and interleukin-6. These biomarkers were shown to be associated with poor quality of life and predictive of adverse events in coronary atherosclerosis and left ventricular dysfunction. Vascular predictive value of other numerous inflammatory markers is being investigated. We herein analyze the role of several mediators of inflammation, affecting vascular functions and leading toward atherosclerotic lesions.

Expanded Network of Inflammatory Markers of Atherogenesis: Where Are We Now?

Inflammatory biomarkers play a pivotal role in atherosclerotic lesions. The plasma levels of these markers are predictive of adverse outcomes such as myocardial infarction and cardiovascular death. The immune system is involved at all stages of atherogenesisviaactivation of monocytes/macrophages and T lymphocytes.Circulating proinflammatory cytokines and chemokines produced by these cells interact with specific receptors on various cells and activate specific signaling pathways, leading to inflammation-induced atherosclerotic lesions. Recent studies have focused on predictive value of inflammatory biomarkers such as C-reactive protein and interleukin-6. These biomarkers were shown to be associated with poor quality of life and predictive of adverse events in coronary atherosclerosis and left ventricular dysfunction. Vascular predictive value of other numerous inflammatory markers is being investigated. We herein analyze the role of several mediators of inflammation, affecting vascular functions and leading toward atherosclerotic lesions.

Decreased paraoxonase and arylesterase activities in the pathogenesis of future atherosclerotic heart disease in women with gestational diabetes mellitus

OBJECTIVE

The aim of this study was to investigate serum paraoxonase, arlyesterase activities, and lipid hydroperoxide (LOOH) levels in patients with gestational diabetes mellitus (GDM).

METHODS

Paraoxonase and arylesterase activities, and LOOH levels were assessed for GDM cases (n = 55) and controls (n = 59). Serum basal and salt-stimulated paraoxonase and arylesterase activities were measured spectrophotometrically. LOOH levels were measured by ferrous oxidation with a xylenol orange assay.

RESULTS

Basal and salt-stimulated paraoxonase and arylesterase activities were significantly lower (p = 0.002, p = 0.004; and p = 0.013, respectively) in patients with GDM compared to controls, while LOOH levels were significantly higher (p < 0.001). Among gestational diabetes patients, serum paraoxonase and arylesterase activities were inversely correlated with LOOH levels (r = - 0.390, p = 0.003; and r = - 0.287, p = 0.034, respectively).

CONCLUSIONS

Findings of the present study have shown that serum paraoxonase and arylesterase activities are significantly reduced in women with GDM. Decreased serum paraoxonase and arylesterase activities might play a role in the potential early pathogenesis for atherosclerotic heart disease in GDM beyond their antioxidant properties.

Effects of acetylsalicylic acid on serum paraoxonase activity, Ox-LDL, coenzyme Q10 and other oxidative stress markers in healthy volunteers

OBJECTIVES

The aim of the study was to examine the effects of acetylsalicylic acid (ASA) on oxidative stress in healthy volunteers.

DESIGN AND METHODS

30 volunteers of which 17 received ASA as 100 mg/day (Group I) and 13 received ASA as 150 mg/day (Group II) for 2 months. Serum paraoxonase 1 (PON1), arylesterase, total antioxidant status (TAS), total oxidant status (TOS), oxidized LDL (Ox-LDL) and coenzyme Q(10) (CoQ(10)) levels were measured before and 1 and 2 months after treatment.

RESULTS

There was no significant differences between the measured parameters of the groups. However, TOS and Ox-LDL levels of group II were significantly reduced after 2 months of treatment (p<0.05).

CONCLUSIONS

Significantly inhibition of LDL oxidation and significantly reduction in TOS levels of group II after 2 months of ASA treatment shows that ASA treatment may contribute to the prevention of atherosclerosis, a beneficial effect which is dose and time dependent.

Paraoxonase: a multifaceted biomolecule

BACKGROUND

Paraoxonase enzyme was first identified as a protective barrier against organophosphorus poisoning. After painstaking research spanning the last three decades, the knowledge about this enzyme has increased immensely. The present review attempts to elaborate the role of paraoxonase enzyme in normal physiology as well as provide an overview of the various disorders in which the enzyme may have a role in etiopathogenesis.

METHODS

The literature was searched from the websites of the National Library of Medicine (http://www.ncbi.nlm.nih.gov/) and Pub Med Central, the U.S. National Library of Medicine's digital archive of life sciences journal literature.

RESULTS

Paraoxonase acts as an important antioxidant enzyme against oxidative stress. The enzyme has been implicated in the pathogenesis of a number of disorders including cardiovascular disorders, cancers etc.

CONCLUSIONS

A better understanding of the molecular mechanism of the enzyme along with the regulatory circuits will help us to utilize agonists to potentiate the anti oxidant actions of the enzyme.