The role of paraoxonase 1 activity in cardiovascular disease: potential for therapeutic intervention

Effects of Moringa oleifera extract on biochemical and histological parameters of sodium valproate induced lungs damage

Sodium valproate- a salt of valproic acid (VPA), is an anticonvulsant used in the treatment of epilepsy and a range of psychiatric conditions that include panic attacks, anxiety, post-traumatic stress, migraine and bipolar disorder etc. VPA can cause direct damage to many tissues due to accumulation of toxic metabolites. Nowadays, phytochemicals are amongst the best options for the treatment of diseases. Moringa oleifera is a popular plant in the tropics owing to its numerous pharmacological and phytochemical properties such as antiproliferative, hepatoprotective, anti-inflammatory, and cardioprotective effects. In the present study, the protective effects of Moringa ethanol extract on oxidative lung damage caused by VPA was assessed biochemically and histologically. Sprague Dawley female rats were divided into 4 groups: Control, Moringa extract (M), sodium valproate (V), and sodium valproate + Moringa extract (V + M). Doses of sodium valproate and Moringa extract (dissolved in physiological saline) were given at 500 mg/kg b.w. and 300 mg/kg b.w. for 15 days, respectively. The rats were sacrificed on the 16th day, lung tissues collected biochemical parameters (glutathione level, antioxidant enzyme activities, oxidative stress biomarker and inflammatory proteins) and histopathological findings obtained from the study indicated increased damage in lung tissue of the valproate administered group. The damage was prevented/decreased upon administration of Moringa to the valproate rats. The present findings revealed that Moringa extract had a protective and therapeutic effect against VPA induced lung damage. Moringa extract demonstrated an ameliorative effect on histopathological and biochemical parameters in valproate induced lung damage.

Molecular Structure of Paraoxonase-1 and Its Modifications in Relation to Enzyme Activity and Biological Functions-A Comprehensive Review

PON1 is a Ca2+-dependent enzyme that indicates a hydrolytic activity towards a broad spectrum of substrates. The mechanism of hydrolysis catalyzed by this enzyme is poorly understood. It was shown that the active site of PON1 is highly dynamic. The catalytic center of this enzyme consists of side chains of amino acids binding two calcium ions, from which the first one performs a structural function and the other one is responsible for the catalytic properties of PON1. This review summarizes available information on the structure of PONs, the role of amino acids located in the active site in specificity, and multiple substrate affinity of enzymes for understanding and explaining the basis of the physiological function of PONs. Moreover, in this paper, we described the changes in the structure of PONs induced by environmental and genetic factors and their association with diseases. The detoxification efficiency depends on the polymorphism of the PON1 gene, especially Q192R. However, data on the association between single-nucleotide polymorphisms (SNPs) in the PON1 gene and cardiovascular or neurodegenerative diseases are insufficient. The reviewed papers may confirm that PON1 is a very promising tool for diagnostics, but further studies are required.

The Molecular Bases of Anti-Oxidative and Anti-Inflammatory Properties of Paraoxonase 1

The anti-oxidative and anti-inflammatory properties of high-density lipoprotein (HDL) are thought to be mediated by paraoxonase 1 (PON1), a calcium-dependent hydrolytic enzyme carried on a subfraction of HDL that also carries other anti-oxidative and anti-inflammatory proteins. In humans and mice, low PON1 activity is associated with elevated oxidized lipids and homocysteine (Hcy)-thiolactone, as well as proteins that are modified by these metabolites, which can cause oxidative stress and inflammation. PON1-dependent metabolic changes can lead to atherothrombotic cardiovascular disease, Alzheimer's disease, and cancer. The molecular bases underlying these associations are not fully understood. Biochemical, proteomic, and metabolic studies have significantly expanded our understanding of the mechanisms by which low PON1 leads to disease and high PON1 is protective. The studies discussed in this review highlight the changes in gene expression affecting proteostasis as a cause of the pro-oxidative and pro-inflammatory phenotypes associated with attenuated PON1 activity. Accumulating evidence supports the conclusion that PON1 regulates the expression of anti-oxidative and anti-inflammatory proteins, and that the disruption of these processes leads to disease.

Dyslipidemia in rheumatoid arthritis: the possible mechanisms

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease, of which the leading cause of death is cardiovascular disease (CVD). The levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), and high-density lipoprotein cholesterol (HDL-c) in RA decrease especially under hyperinflammatory conditions. It is conflictive with the increased risk of CVD in RA, which is called "lipid paradox". The systemic inflammation may explain this apparent contradiction. The increased systemic proinflammatory cytokines in RA mainly include interleukin-6(IL-6)、interleukin-1(IL-1)and tumor necrosis factor alpha(TNF-α). The inflammation of RA cause changes in the subcomponents and structure of HDL particles, leading to a weakened anti-atherosclerosis function and promoting LDL oxidation and plaque formation. Dysfunctional HDL can further worsen the abnormalities of LDL metabolism, increasing the risk of cardiovascular disease. However, the specific mechanisms underlying lipid changes in RA and increased CVD risk remain unclear. Therefore, this article comprehensively integrates the latest existing literature to describe the unique lipid profile of RA, explore the mechanisms of lipid changes, and investigate the impact of lipid changes on cardiovascular disease.

Proteomic Exploration of Paraoxonase 1 Function in Health and Disease

High-density lipoprotein (HDL) exhibits cardio- and neuro-protective properties, which are thought to be promoted by paraoxonase 1 (PON1), a hydrolytic enzyme associated with an HDL subfraction also enriched with an anticoagulant protein (PROS1) and amyloid beta-transport protein clusterin (CLU, APOJ). Reduced levels of PON1 activity, characterized biochemically by elevated levels of homocysteine (Hcy)-thiolactone, oxidized lipids, and proteins modified by these metabolites in humans and mice, are associated with pathological abnormalities affecting the cardiovascular system (atherothrombosis) and the central nervous system (cognitive impairment, Alzheimer's disease). The molecular bases of these abnormalities have been largely unknown. Proteomic and metabolic studies over the past decade have significantly contributed to our understanding of PON1 function and the mechanisms by which PON1 deficiency can lead to disease. Recent studies discussed in this review highlight the involvement of dysregulated proteostasis in the pro-oxidative, pro-atherothrombotic, and pro-amyloidogenic phenotypes associated with low PON1 activity.

Paraoxonases at the Heart of Neurological Disorders

Paraoxonase enzymes serve as an important physiological redox system that participates in the protection against cellular injury caused by oxidative stress. The PON enzymes family consists of three members (PON-1, PON-2, and PON-3) that share a similar structure and location as a cluster on human chromosome 7. These enzymes exhibit anti-inflammatory and antioxidant properties with well-described roles in preventing cardiovascular disease. Perturbations in PON enzyme levels and their activity have also been linked with the development and progression of many neurological disorders and neurodegenerative diseases. The current review summarizes the available evidence on the role of PONs in these diseases and their ability to modify risk factors for neurological disorders. We present the current findings on the role of PONs in Alzheimer's disease, Parkinson's disease, and other neurodegenerative and neurological diseases.

Electronegative LDL Is Associated with Plaque Vulnerability in Patients with Ischemic Stroke and Carotid Atherosclerosis

Owing to the high risk of recurrence, identifying indicators of carotid plaque vulnerability in atherothrombotic ischemic stroke is essential. In this study, we aimed to identify modified LDLs and antioxidant enzymes associated with plaque vulnerability in plasma from patients with a recent ischemic stroke and carotid atherosclerosis. Patients underwent an ultrasound, a CT-angiography, and an ¹⁸F-FDG PET. A blood sample was obtained from patients (n = 64, 57.8% with stenosis ≥50%) and healthy controls (n = 24). Compared to the controls, patients showed lower levels of total cholesterol, LDL cholesterol, HDL cholesterol, apolipoprotein B (apoB), apoA-I, apoA-II, and apoE, and higher levels of apoJ. Patients showed lower platelet-activating factor acetylhydrolase (PAF-AH) and paraoxonase-1 (PON-1) enzymatic activities in HDL, and higher plasma levels of oxidized LDL (oxLDL) and electronegative LDL (LDL(-)). The only difference between patients with stenosis ≥50% and <50% was the proportion of LDL(-). In a multivariable logistic regression analysis, the levels of LDL(-), but not of oxLDL, were independently associated with the degree of carotid stenosis (OR: 5.40, CI: 1.15-25.44, p < 0.033), the presence of hypoechoic plaque (OR: 7.52, CI: 1.26-44.83, p < 0.027), and of diffuse neovessels (OR: 10.77, CI: 1.21-95.93, p < 0.033), indicating that an increased proportion of LDL(-) is associated with vulnerable atherosclerotic plaque.

Cardioprotective Role for Paraoxonase-1 in Chronic Kidney Disease

Paraoxonase-1 (PON-1) is a hydrolytic enzyme associated with HDL, contributing to its anti-inflammatory, antioxidant, and anti-atherogenic properties. Deficiencies in PON-1 activity result in oxidative stress and detrimental clinical outcomes in the context of chronic kidney disease (CKD). However, it is unclear if a decrease in PON-1 activity is mechanistically linked to adverse cardiovascular events in CKD. We investigated the hypothesis that PON-1 is cardioprotective in a Dahl salt-sensitive model of hypertensive renal disease. Experiments were performed on control Dahl salt-sensitive rats (SSMcwi, hereafter designated SS-WT rats) and mutant PON-1 rats (SS-Pon1em1Mcwi, hereafter designated SS-PON-1 KO rats) generated using CRISPR gene editing technology. Age-matched 10-week-old SS and SS-PON-1 KO male rats were maintained on high-salt diets (8% NaCl) for five weeks to induce hypertensive renal disease. Echocardiography showed that SS-PON-1 KO rats but not SS-WT rats developed compensated left ventricular hypertrophy after only 4 weeks on the high-salt diet. RT-PCR analysis demonstrated a significant increase in the expression of genes linked to cardiac hypertrophy, inflammation, and fibrosis, as well as a significant decrease in genes essential to left ventricular function in SS-PON-1 KO rats compared to SS-WT rats. A histological examination also revealed a significant increase in cardiac fibrosis and immune cell infiltration in SS-PON-1 KO rats, consistent with their cardiac hypertrophy phenotype. Our data suggest that a loss of PON-1 in the salt-sensitive hypertensive model of CKD leads to increased cardiac inflammation and fibrosis as well as a molecular and functional cardiac phenotype consistent with compensated left ventricular hypertrophy.

HDL Composition, Heart Failure, and Its Comorbidities

Although research on high-density lipoprotein (HDL) has historically focused on atherosclerotic coronary disease, there exists untapped potential of HDL biology for the treatment of heart failure. Anti-oxidant, anti-inflammatory, and endothelial protective properties of HDL could impact heart failure pathogenesis. HDL-associated proteins such as apolipoprotein A-I and M may have significant therapeutic effects on the myocardium, in part by modulating signal transduction pathways and sphingosine-1-phosphate biology. Furthermore, because heart failure is a complex syndrome characterized by multiple comorbidities, there are complex interactions between heart failure, its comorbidities, and lipoprotein homeostatic mechanisms. In this review, we will discuss the effects of heart failure and associated comorbidities on HDL, explore potential cardioprotective properties of HDL, and review novel HDL therapeutic targets in heart failure.

Genes and Longevity of Lifespan

Aging is a complex process indicated by low energy levels, declined physiological activity, stress induced loss of homeostasis leading to the risk of diseases and mortality. Recent developments in medical sciences and an increased availability of nutritional requirements has significantly increased the average human lifespan worldwide. Several environmental and physiological factors contribute to the aging process. However, about 40% human life expectancy is inherited among generations, many lifespan associated genes, genetic mechanisms and pathways have been demonstrated during last decades. In the present review, we have evaluated many human genes and their non-human orthologs established for their role in the regulation of lifespan. The study has included more than fifty genes reported in the literature for their contributions to the longevity of life. Intact genomic DNA is essential for the life activities at the level of cell, tissue, and organ. Nucleic acids are vulnerable to oxidative stress, chemotherapies, and exposure to radiations. Efficient DNA repair mechanisms are essential for the maintenance of genomic integrity, damaged DNA is not replicated and transferred to next generations rather the presence of deleterious DNA initiates signaling cascades leading to the cell cycle arrest or apoptosis. DNA modifications, DNA methylation, histone methylation, histone acetylation and DNA damage can eventually lead towards apoptosis. The importance of calorie restriction therapy in the extension of lifespan has also been discussed. The role of pathways involved in the regulation of lifespan such as DAF-16/FOXO (forkhead box protein O1), TOR and JNK pathways has also been particularized. The study provides an updated account of genetic factors associated with the extended lifespan and their interactive contributory role with cellular pathways.

Prevalence and mortality of COVID-19 are associated with the L55M functional polymorphism of Paraoxonase 1

Introduction

Accumulating evidence recommends that infectious diseases including coronavirus disease 2019 (COVID-19) are often associated with oxidative stress and inflammation. Paraoxonase 1 (PON1, OMIM: 168,820), a member of the paraoxonase gene family, has antioxidant properties. Enzyme activity of paraoxonase depends on a variety of influencing factors such as polymorphisms of PON1, ethnicity, gender, age, and a number of environmental variables. The PON1 has two common functional polymorphisms, namely, Q192R (rs662) and L55M (rs854560). The R192 and M55 alleles are associated with increase and decrease in enzyme activity, respectively.

Objective

The present study was conducted to investigate the possible association of rs662 and rs854560 polymorphisms with morbidity and mortality of COVID-19.

Methods

Data for the prevalence, mortality, and amount of accomplished diagnostic test (per 10⁶ people) on 25 November 2020 from 48 countries were included in the present study. The Human Development Index (HDI) was used as a potential confounding variable.

Results

The frequency of M55 was positively correlated with the prevalence (partial r = 0.487, df = 36, p = 0.002) and mortality of COVID-19 (partial r = 0.551, df = 36, p < 0.001), after adjustments for HDI and amount of the accomplished diagnostic test as possible confounders.

Conclusions

This means that countries with higher M55 frequency have higher prevalence and mortality of COVID-19.

Myeloperoxidase-induced modification of HDL by isolevuglandins inhibits paraoxonase-1 activity

Reduced activity of paraoxonase 1 (PON1), a high-density lipoprotein (HDL)-associated enzyme, has been implicated in the development of atherosclerosis. Post-translational modifications of PON1 may represent important mechanisms leading to reduced PON1 activity. Under atherosclerotic conditions, myeloperoxidase (MPO) is known to associate with HDL. MPO generates the oxidants hypochlorous acid and nitrogen dioxide, which can lead to post-translational modification of PON1, including tyrosine modifications that inhibit PON1 activity. Nitrogen dioxide also drives lipid peroxidation, leading to the formation of reactive lipid dicarbonyls such as malondialdehyde and isolevuglandins, which modify HDL and could inhibit PON1 activity. Because isolevuglandins are more reactive than malondialdehyde, we used in vitro models containing HDL, PON1, and MPO to test the hypothesis that IsoLG formation by MPO and its subsequent modification of HDL contributes to MPO-mediated reductions in PON1 activity. Incubation of MPO with HDL led to modification of HDL proteins, including PON1, by IsoLG. Incubation of HDL with IsoLG reduced PON1 lactonase and antiperoxidation activities. IsoLG modification of recombinant PON1 markedly inhibited its activity, while irreversible IsoLG modification of HDL before adding recombinant PON1 only slightly inhibited the ability of HDL to enhance the catalytic activity of recombinant PON1. Together, these studies support the notion that association of MPO with HDL leads to lower PON1 activity in part via IsoLG-mediated modification of PON1, so that IsoLG modification of PON1 could contribute to increased risk for atherosclerosis, and blocking this modification might prove beneficial to reduce atherosclerosis.

Changes in redox plasma proteome of Pon1-/- mice are exacerbated by a hyperhomocysteinemic diet

High-density lipoprotein (HDL), in addition to promoting reverse cholesterol transport, possesses anti-oxidative, anti-inflammatory, and antithrombotic activities, which are thought to be promoted by paraoxonase 1 (PON1), an HDL-associated enzyme. Reduced levels of PON1 are associated with increased oxidative stress and cardiovascular disease both in humans and Pon1^-/- mice. However, molecular basis of these associations are not fully understood. We used label-free mass spectrometry and Ingenuity Pathway Analysis bioinformatics resources to examine plasma proteomes in four-month-old Pon1^-/- mice (n = 32) and their Pon1^+/+ siblings (n = 15) fed with a hyper-homocysteinemic (HHcy) diet. We found that inactivation of the Pon1 gene resulted in dysregulation of proteins involved in the maintenance of redox homeostasis in mice. Redox-responsive proteins affected by Pon1^-/- genotype were more numerous in mice fed with HHcy diet (18 out of 89, 20%) than in mice fed with a control diet (4 out of 50, 8%). Most of the redox-related proteins affected by Pon1^-/- genotype in mice fed with a control diet (3 out of 4, 75%) were also affected in HHcy mice, while the majority of Pon1^-/- genotype-dependent redox proteins in HHcy mice (15 out of 18, 83%) were not affected by Pon1^-/- genotype in control diet animals. In addition to redox-related proteins, we identified proteins involved in acute phase response, complement/blood coagulation, lipoprotein/lipid metabolism, immune response, purine metabolism, glucose metabolism, and other proteins that were dysregulated by Pon1^-/- genotype in HHcy mice. Taken together, our findings suggest that Pon1 interacts with proteins involved in antioxidant defenses and other processes linked to cardiovascular disease. Dysregulation of these processes provides an explanation for the pro-oxidant and pro-atherogenic phenotypes observed in Pon1^-/- mice and humans with attenuated PON1 levels.

In vivo/in silico insight into the effect of titanium dioxide nanoparticle on serum paraoxonase 1 activity in rat

Serum paraoxonase1 (PON1) has special function in human body organism including the antioxidant and anti-atherogenic properties. In the present study, the effect of TiO₂ nanoparticles on the activity and structure of the PON1 has been evaluated through in vivo and in silico methods. After treatments of the rats with different doses of TiO₂ NPs, blood samples were collected and serum PON1 activity was measured by phenylacetate and paraoxon as substrate. In addition, the effects of TiO₂ NP on enzyme structure were analyzed through Molecular dynamic (MD) simulation via Gromacs software package to obtain RMSD, RMSF, Rg, SASA, and secondary structures values. A significant reduction (p < 0.05) in arylesterase & paraoxonase activities of serum PON1 were monitored in Spectrometric assays when rats were treated with 150 and 200 mg/kg doses of TiO₂ NPs. RMSD, RG, RMSF, and SASA values in the presence of TiO₂ have been increased while RMSF values of the L1 and L2 loops (gate of the catalytic site) have been reduced. Moreover, Hydrogen bonds and secondary structure values of the enzyme decreased in the presence of TiO₂ NP. All of these MD simulation results could indicate the instability of the PON1 structure bounded to TiO₂ NP. TiO₂ NP could cause a disturbance in the enzyme structure and function of PON1 based on the results. PON1 prevents oxidation of LDL and can delay atherosclerosis progression while in the presence of TiO₂ NP these protective effects could be endangered.Communicated by Ramaswamy H. Sarma.

The Lipid Paradox as a Metabolic Checkpoint and Its Therapeutic Significance in Ameliorating the Associated Cardiovascular Risks in Rheumatoid Arthritis Patients

While the most common manifestations associated with rheumatoid arthritis (RA) are synovial damage and inflammation, the systemic effects of this autoimmune disorder are life-threatening, and are prevalent in 0.5–1% of the population, mainly associated with cardiovascular disorders (CVDs). Such effects have been instigated by an altered lipid profile in RA patients, which has been reported to correlate with CV risks. Altered lipid paradox is related to inflammatory burden in RA patients. The review highlights general lipid pathways (exogenous and endogenous), along with the changes in different forms of lipids and lipoproteins in RA conditions, which further contribute to elevated risks of CVDs like ischemic heart disease, atherosclerosis, myocardial infarction etc. The authors provide a deep insight on altered levels of low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides (TGs) in RA patients and their consequence on the cardiovascular health of the patient. This is followed by a detailed description of the impact of anti-rheumatoid therapy on the lipid profile in RA patients, comprising DMARDs, corticosteroids, anti-TNF agents, anti-IL-6 agents, JAK inhibitors and statins. Furthermore, this review elaborates on the prospects to be considered to optimize future investigation on management of RA and treatment therapies targeting altered lipid paradigms in patients.

Current Understanding of the Relationship of HDL Composition, Structure and Function to Their Cardioprotective Properties in Chronic Kidney Disease

In the general population, the ability of high-density lipoproteins (HDLs) to promote cholesterol efflux is a predictor of cardiovascular events, independently of HDL cholesterol levels. Although patients with chronic kidney disease (CKD) have a high burden of cardiovascular morbidity and mortality, neither serum levels of HDL cholesterol, nor cholesterol efflux capacity associate with cardiovascular events. Important for the following discussion on the role of HDL in CKD is the notion that traditional atherosclerotic cardiovascular risk factors only partially account for this increased incidence of cardiovascular disease in CKD. As a potential explanation, across the spectrum of cardiovascular disease, the relative contribution of atherosclerotic cardiovascular disease becomes less important with advanced CKD. Impaired renal function directly affects the metabolism, composition and functionality of HDL particles. HDLs themselves are a heterogeneous population of particles with distinct sizes and protein composition, all of them affecting the functionality of HDL. Therefore, a more specific approach investigating the functional and compositional features of HDL subclasses might be a valuable strategy to decipher the potential link between HDL, cardiovascular disease and CKD. This review summarizes the current understanding of the relationship of HDL composition, metabolism and function to their cardio-protective properties in CKD, with a focus on CKD-induced changes in the HDL proteome and reverse cholesterol transport capacity. We also will highlight the gaps in the current knowledge regarding important aspects of HDL biology.

Effects of Moringa oleifera Leaf Extract on Diabetes-Induced Alterations in Paraoxonase 1 and Catalase in Rats Analyzed through Progress Kinetic and Blind Docking

In our study, we aimed to evaluate the effects of Moringa oleifera leaves extract on rat paraoxonase 1 (rPON1) and catalase (rCAT) activities in alloxan-induced diabetic rats. Our study included three groups; group C (control, n = 5); group D (diabetic, n = 5); and group DM (M. oleifera extract-supplemented diabetic rats, n = 5). Daily oral administration of M. oleifera extract at 200 mg/kg doses produced an increase in endogenous antioxidants. Serum rPON1 (lactonase) and liver cytosol catalase activities were determined by a spectrophotometric assay using progress curve analysis. We found a decrease in the Vm value of rPON1 in diabetic rats, but dihydrocoumarin (DHC) affinity (Km) was slightly increased. The value of Vm for the DM group was found to be reduced approximately by a factor of 3 compared with those obtained for group C, whereas Km was largely changed (96 times). Catalase activity was significantly higher in the DM group. These data suggest that the activation of rPON1 and rCAT activities by M. oleifera extracts may be mediated via the effect of the specific flavonoids on the enzyme structure. In addition, through molecular blind docking analysis, rPON1 was found to have two binding sites for flavonoids. In contrast, flavonoids bound at four sites in rCAT. In conclusion, the data suggest that compounds from M. oleifera leaves extract were able to influence the catalytic activities of both enzymes to compensate for the changes provoked by diabetes in rats.

Changes in High-Density Lipoproteins Related to Outcomes in Patients with Acute Stroke

Modifications in high-density lipoprotein (HDL) particle sizes and HDL-binding proteins have been reported in stroke patients. We evaluated whether the lipoprotein profile, HDL composition and functionality were altered in stroke patients according to their clinical outcome using the modified Rankin Score at 3 months. Plasma samples were obtained from stroke patients treated with intravenous thrombolysis. Levels of cardiovascular and inflammatory markers in plasma were measured using the Human CVD Panel 1 (Milliplex^® MAP). Lipoprotein subfractions from plasma were quantified by non-denaturing acrylamide gel electrophoresis, using the Lipoprint^®-System (Quantimetrix^®), and HDLs were isolated by ultracentrifugation. Relative amounts of paraoxonase-1 (PON1) and alpha-1 anti-trypsin (AAT) in the isolated HDLs were determined by Western blot. HDL anti-inflammatory function was evaluated in human blood-brain barrier endothelial cells stimulated with 100 ng/mL TNFα, and HDL antioxidant function was evaluated via their capacity to limit copper-induced low-density lipoprotein oxidation. Stroke patients with unfavorable outcomes had a lower proportion of small-sized HDLs and increased plasma levels of E-selectin (SELE) and the intercellular adhesion molecule 1 (ICAM1). HDLs from patients with unfavorable outcomes had lower levels of PON1 and displayed a blunted capacity to reduce the expression of SELE, interleukin 8 (IL8) and the monocyte chemoattractant protein-1 (MCP1) mRNA induced by TNFα in endothelial cells. These HDLs also had a reduced antioxidant capacity relative to HDLs from healthy donors. In conclusion, an increased ratio of large/small HDLs with impaired anti-inflammatory and antioxidant capacities was associated with unfavorable outcomes in stroke patients. Alteration of HDL functionality was mainly associated with a low amount of PON1 and high amount of AAT.

Phenolic Substances in Foods and Anticarcinogenic Properties: A Public Health Perspective

The interest in polyphenols from vegetable sources has been progressively increased because of the demonstrated correlation between their abundance in certain foods or food preparations of traditional importance and heritage, and the answer of anti-inflammatory strategies in hospitalized patients in the presence of polypehnol-rich foods (as a complementary therapy). Consequently, research involving the accessory role of polyphenols as anti-tumoral aids have been carried out with the aim of finding new additional strategies. The purpose of this paper to evaluate the role of phenolic compounds in foods with reference to health effects for human beings. The importance of these molecules has been evaluated by the health and safety perspectives in terms of: fight to cardiovascular diseases; prevention of chronic-degenerative disorders; general antioxidant properties; and anticarcinogenic features. Moreover, the role of polyphenols-rich foods as anticancer agents has been discussed with relation to two distinct "action plans" on the public hygiene level: the promotion of human health on the one side (for non-hospitalized and normal subjects), and reliable contrasting strategies in cancer patients.

High-Density Lipoproteins and Apolipoprotein A1

High-density lipoprotein (HDL) and its main protein component apolipoprotein (apo)A-I, play an important role in cholesterol homeostasis. It has been demonstrated that HDLs comprise of a very heterogeneous group of particles, not only regarding size but also composition. HDL's best described function is its role in the reverse cholesterol transport, where lipid-free apoA-I or small HDLs can accept and take up cholesterol from peripheral cells and subsequently transport this to the liver for excretion. However, several other functions have also been described, like anti-oxidant, anti-inflammatory and anti-thrombotic effects. In this article, the general features, synthesis and metabolism of apoA-I and HDLs will be discussed. Additionally, an overview of HDL functions will be given, especially in the context of some major pathologies like cardiovascular disease, cancer and diabetes mellitus. Finally, the therapeutic potential of raising HDL will be discussed, focussing on the difficulties of the past and the promises of the future.

Effects of Securigera securidaca (L.) Degen & Dorfl seed extract combined with glibenclamide on paraoxonase1 activity, lipid profile and peroxidation, and cardiovascular risk indices in diabetic rats

Introduction: Seeds of Securigera securidaca (L.) Degen & Dorfl are rich in flavonoids and phenolic acids which have potent biological effects. The current study was undertaken to evaluate the effects of hydroalcoholic extract of S. securidaca seeds (HESS) alone, and in combination with a standard drug, glibenclamide (GB) on paraoxonase1 (PON1) activity, lipid profile and peroxidation, and cardiovascular risk indices in streptozotocin (STZ) induced diabetic rats.

Methods: Forty-eight male Wistar rats were randomly divided into eight equal groups and orally treated with various doses of HESS (100, 200, 400 mg/kg) alone and in combination with GB (5 mg/kg) for 35 consecutive days. After blood sampling, lipid profile including triglyceride (TG), cholesterol, high, low and very low-density lipoprotein-cholesterol (HDL-C, LDL-C, and VLDL-C), as well as serum PON1 activity, were assessed. Malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), and high-sensitivity C-reactive protein (hs-CRP) levels were also measured. Several indices of cardiovascular risk and the correlation between PON1 activity and these indices were calculated based on the obtained results from the lipid profile.

Results: Induction of diabetes could dramatically alter all of the parameters mentioned above, and the lower dose of HESS (100 mg/kg) was not effective in restoring the parameters. However, the higher doses (200 and 400 mg/kg) alone and in combination with GB could significantly improve lipid profile, restore PON1 activity, and decrease cardiovascular risk indices, MDA, as well. However, neither HESS nor GB could significantly reduce TNF-α and hs-CRP. A significant negative correlation also was detected between PON1 activity and cardiovascular risk indices.

Conclusion: conclusively, HESS can be considered as a potent antihyperlipidemic agent with remarkable cardioprotective effects and can potentiate the antidiabetic effects of GB.

Comparison of linear periodized and non-periodized combined training in health markers and physical fitness of adults with obesity: Clinical trial protocol

The literature discusses that combined training, aerobic more resistance exercises in the same session, is a suitable strategy for people with obesity and that exercise periodization leads to positive health outcomes; however, the implication of different periodizations of combined training for health outcomes in obese adults requires further investigation. The aim of the study will be to describe the methodology used to compare the effect of linear periodized and non-periodized combined training on health markers and health-related physical fitness in adults with obesity. This is a blinded randomized controlled clinical trial investigating adults with obesity in the age group 20-50 years. The sample will be non-probabilistic, and participants will be allocated randomly into one of three groups: control group (CG), non-periodized group (NG), and periodized group (PG). The intervention will occur in 60-min sessions, 3 days a week for 16 weeks, with 1 week dedicated to familiarization with the training and 15 weeks of combined training (aerobic followed by resistance in the same session). The PG group will perform three mesocycles of 5 weeks each, progressing in intensity throughout the intervention [aerobic: from 40-49% to 60-69% of heart rate reserve (HRR); strength: from 12 to 14 maximum repetitions (MR) to 8 to 10MR]; the NG group will maintain the same relative intensity throughout the study (aerobic: 50-59% of HRR; strength: 2 sets of 10-12 MR). Participants in the CG group will maintain their usual activities without the proposed intervention. Pre- and post-intervention assessments will be performed for biochemical markers, body composition, cardiovascular parameters, cardiorespiratory fitness, maximum upper and lower limb strength, flexibility, and subjective health-related parameters. This project was approved by the Committee of Ethics and Research with Human Beings of the institution of origin (protocol 2,448,674) and registered in the Brazilian Registry of Clinical Trials (RBR-3c7rt3).

Paraoxonase 1 Q192R genotype and activity affect homocysteine thiolactone levels in humans

Genetic or nutritional deficiencies in 1 carbon and homocysteine (Hcy) metabolism elevate Hcy-thiolactone levels and are associated with cardiovascular and neurologic diseases. Hcy-thiolactone causes protein damage, cellular toxicity, and proatherogenic changes in gene expression in human cells and tissues. A polymorphic cardio-protective enzyme, paraoxonase 1 (PON1), hydrolyzes Hcy-thiolactone in vitro. However, whether Hcy-thiolactone hydrolysis is a physiologic function of the PON1 protein and whether polymorphisms in the PON1 gene affect Hcy-thiolactone levels in humans was unknown. Here we show that the PON1-192 genotype, which affects the enzymatic activity of the PON1 protein, also affected urinary Hcy-thiolactone levels, normalized to creatinine. Carriers of the PON1-192R allele had significantly lower Hcy-thiolactone/creatinine levels than individuals carrying the PON1-192Q allele. Individuals with low serum PON1 paraoxonase activity had significantly higher Hcy-thiolactone/creatinine levels compared with individuals with high paraoxonase activity. In contrast, Hcy-thiolactone/creatinine levels were unaffected by serum PON1 arylesterase activity or by PON1 protein levels. Taken together, these findings suggest that PON1 hydrolyzes Hcy-thiolactone in humans and that the interindividual variations in PON1 genotype/activity can modulate the pathology of hyperhomocysteinemia.-Perła-Kaján, J., Borowczyk, K., Głowacki, R., Nygård, O., Jakubowski, H. Paraoxonase 1 Q192r genotype and activity affect homocysteine thiolactone levels in humans.

Organophosphorus Xenobiotic Toxicology

Originally, organophosphorus (OP) toxicology consisted of acetylcholinesterase inhibition by insecticides and chemical threat agents acting as phosphorylating agents for serine in the catalytic triad, but this is no longer the case. Other serine hydrolases can be secondary OP targets, depending on the OP structure, and include neuropathy target esterase, lipases, and endocannabinoid hydrolases. The major OP herbicides are glyphosate and glufosinate, which act in plants but not animals to block aromatic amino acid and glutamine biosynthesis, respectively, with safety for crops conferred by their expression of herbicide-tolerant targets and detoxifying enzymes from bacteria. OP fungicides, pharmaceuticals including calcium retention agents, industrial chemicals, and cytochrome P450 inhibitors act by multiple noncholinergic mechanisms, often with high potency and specificity. One type of OP-containing fire retardant forms a highly toxic bicyclophosphate γ-aminobutyric acid receptor antagonist upon combustion. Some OPs are teratogenic, mutagenic, or carcinogenic by known mechanisms that can be avoided as researchers expand knowledge of OP chemistry and toxicology for future developments in bioregulation.

Q192R polymorphism in the PON1 gene and familial hypercholesterolemia in a Saudi population

BACKGROUND

Familial hypercholesterolemia (FH) is an autosomal dominant condition characterized by abnormal levels of low-density lipoprotein (LDL) in the blood. FH is a risk factor for atherosclerosis and cardiovascular disease. The relationship between the paraoxonase 1 (PON1) gene, atherosclerosis and coronary artery disease has not been studied in Saudi patients.

OBJECTIVE

To investigate the genetic associations of the Q192R polymorphism in the PON1 gene with FH in Saudi patients.

DESIGN

Case-control study.

SETTING

Tertiary care center, Riyadh.

METHODS

Two hundred Saudi patients were enrolled in this study, including 100 patients with FH and 100 healthy controls, during the period from January 2012 to March 2013. Serum was separated from coagulated blood (3 mL) and used for analysis of lipid profiles. Genomic DNA was isolated from anticoagulant-treated blood (2 mL). Genotyping for the Q192R polymorphism was performed by polymerase chain reaction-restriction fragment length polymorphism analysis, followed by 3% agarose gel electrophoresis.

MAIN OUTCOME MEASURE

The strength of association between the Q192R polymorphism and FH in the Saudi population.

RESULTS

We confirmed that QR versus QQ (odds ratio [OR]: 1.55; 95% confidence interval [CI]: 1.05-3.43; P=.03), QR+RR versus QQ (OR: 1.98; 95% CI: 1.13-3.49; P=.01), and R versus Q (OR: 1.68; 95% CI: 1.09- 2.59; P=.01) in the Q192R polymorphism were associated with FH in the Saudi population.

CONCLUSION

In conclusion, the Q192R polymorphism in the PON1 gene is associated with FH in the Saudi population. Our results confirmed that the R allele, QR, and dominant model genotypes were associated with FH.

LIMITATION

Only a single variant (Q192R) was analyzed, and the medical and family histories of the patients were not known.

Serum Oxidative Stress Levels in Patients with Nasal Septal Deviation

Objective

Comparison of the total oxidant status (TOS), total antioxidant status (TAS) and paraoxonase (PON1) serum levels in patients with nasal septum deviation (NSD) and healthy subjects.

Methods

The TAS, TOS, and PON1 serum levels of 47 patients with NSD (mean age 35.3) and 50 healthy subjects (mean age 37.8) were compared in this study.

Results

We found significantly higher TAS levels in the control group (p<0.001). The mean TAS value was 1.196 mmoL/L in the control group, whereas it was 1.046 mmoL/L in the NSD group. On the other hand, TOS was significantly higher in the NSD group (p<0.001). We found that the mean TOS value was 6.600 mmoL/L in the control group, and 20.194 mmoL/L in the NSD group. The NSD and control groups had similar PON1 levels (p=0.446). The mean PON1 value was 279.64 U/L in the control group, and 324.21 U/L in the NSD group.

Conclusion

We detected higher TOS and lower TAS levels in patients with NSD compared to healthy subjects. These results indicate that patients with NSD are exposed to oxidative stress.

FGF21 ameliorates diabetic cardiomyopathy by activating the AMPK-paraoxonase 1 signaling axis in mice

The aim of the present study is to explore the molecular mechanism of fibroblast growth factor 21 (FGF21) in protecting against diabetic cardiomyopathy (DCM). Streptozotocin/high-fat diet (STZ/HFD) was used to induced diabetes in FGF21-deficient mice and their wild-type littermates, followed by evaluation of the difference in DCM between the two genotypes. Primary cultured cardiomyocytes were also used to explore the potential molecular mechanism of FGF21 in the protection of high glucose (HG)-induced cardiomyocyte injury. STZ/HFD-induced cardiomyopathy was exacerbated in FGF21 knockout mice, which was accompanied by a significant reduction in cardiac AMP-activated protein kinase (AMPK) activity and paraoxonase 1 (PON1) expression. By contrast, adeno-associated virus (AAV)-mediated overexpression of FGF21 in STZ/HFD-induced diabetic mice significantly enhanced cardiac AMPK activity, PON1 expression and its biological activity, resulting in alleviated DCM. In cultured cardiomyocytes, treatment with recombinant mouse FGF21 (rmFGF21) counteracted HG-induced oxidative stress, mitochondrial dysfunction, and inflammatory responses, leading to increased AMPK activity and PON1 expression. However, these beneficial effects of FGF21 were markedly weakened by genetic blockage of AMPK or PON1. Furthermore, inactivation of AMPK also markedly blunted FGF21-induced PON1 expression but significantly increased HG-induced cytotoxicity in cardiomyocytes, the latter of which was largely reversed by adenovirus-mediated PON1 overexpression. These findings suggest that FGF21 ameliorates DCM in part by activation of the AMPK-PON1 axis.

Inflammation and the pathogenesis of atherosclerosis in systemic lupus erythematosus

Atherosclerosis is a complicated inflammatory process characterized by the interactions of numerous different moieties including lipids, enzymes, endothelial cells, cytokines, chemokines, leukocytes, adhesion molecules, complement and antibodies. As in the pathogenesis of many lupus disease processes, the increased risk of atherosclerosis seen in systemic lupus erythematosus (SLE) is likely due to the complex interplay of many of these inflammatory mediators. Expanding our understanding of the pathogenesis of atherosclerosis in SLE is critical if we are to improve the quality of care and reduce mortality in this vulnerable population.

Paraoxonase 1 gene polymorphisms and enzyme activities in coronary artery disease and its relationship to serum lipids and glycemia

OBJECTIVES

Oxidative stress and inflammation are important processes in development of atherosclerosis. Paraoxonase 1 (PON1) is a bioscavenger enzyme associated with inflammation and oxidative stress. We evaluate the association of two single nucleotide polymorphisms in PON1 gene, and enzyme activities with lipid profile and glycemia.

METHODS

This case-control study consisted of 126 patients with coronary artery disease (CAD) and 203 healthy controls. PON Q192R and L55M polymorphisms were detected by real-time PCR. Paraoxonase and arylesterase activities were determined spectrophotometrically. Blood glucose, cholesterol, triglycerides, HDL, and LDL were measured.

RESULTS

PON1 QR192 polymorphism had a major effect on paraoxonase but no effect on arylesterase serum activities. Paraoxonase activity was higher in RR genotype and lowest in QQ genotype. Paraoxonase and arylesterase activities were higher in LL and lower in MM genotypes of PON1 LM55 polymorphism. RQ and LM variants showed intermediate activities between respective homozygous. Elevated concentrations of triglycerides in cases correlate with QQ variant or the presence of M allele. Glucose levels were elevated in cases with QQ variant or with the presence of M allele. Cholesterol and LDL did not show variations in control and cases with any variant of both polymorphisms. HDL is lower in cases with respect to controls independently of genotypes. All differences were significant with p<0.05.

CONCLUSIONS

Our results confirm the relationship between variations in PON1 activities and lipid metabolism, and showed that genetically programmed low PON1 activities would have certain responsibility in the increase in glycemia and concomitantly the aggravation of atherosclerotic disease.

The relationship between serum paraoxonase levels and carotid atherosclerotic plaque formation in Alzheimer's patients

Low paraoxonase 1 (PON1) activity and carotid atherosclerosis have been suggested to be important risk factors for dementia. However, the studies to date could not fully clarify the relationship between PON1, carotid atherosclerosis and dementia. The present study aimed to measure carotid atherosclerosis and PON1 activity in Alzheimer's Disease and to evaluate the relationship between them. The study included 25 Alzheimer's patients and 25 control subjects, for a total of 50 individuals. The study measured the serum PON1 activity and other biochemical parameters and carotid atherosclerotic plaque values of the participants. The mean paraoxonase activity (31.06±2.31U/L) was significantly lower in the Alzheimer's group compared to the control group (59.05±7.05U/L) (P<0.001). Nonetheless, the carotid plaque values were significantly higher in the patient group (3.02±0.52mm) compared to the control group (1.84±0.45mm) (P<0.001). Furthermore, there was a negative correlation (81.0%) between PON1 activity and carotid plaque in the overall study group (P<0.05). Also serum homocystein level was higher in the patient group (22.15±7.05) compared to the control group (13.30±3.32). In conclusion, our findings show inverse association between PON1 activity and carotid atherosclerosis in Alzheimer patients: the lower the PON1 activity the more progressed the atherosclerotic process in AD.

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.

HDL as a prognostic biomarker for coronary atherosclerosis: the role of inflammation

INTRODUCTION

Emerging evidence suggests that the role of high density lipoprotein (HDL) in the atherosclerotic process is not as clear as previously thought, since atheroprotective HDL becomes atherogenic in states of increased inflammatory processes.

AREAS COVERED

In this review we aim to elucidate the role of HDL as a prognostic biomarker and we discuss therapeutic approaches that aim to increase HDL and their possible clinical benefit.

EXPERT OPINION

Given the structural variability and biological complexity of the HDL particle, its role in the atherosclerotic process is far from clear. According to current evidence, the atheroprotective role of HDL turns atherogenic in states of increased inflammatory processes, while even minor alterations in systemic inflammation are likely to hinder the endothelial protective effects of HDL. In accordance, significant data have revealed that HDL-related drugs may be effective in reducing cardiovascular mortality; however they are not as encouraging or unanimous as expected. Possible future goals could be to quantify either HDL subclasses or functions in an attempt to reach safer conclusions as to the prognostic importance of HDL in coronary atherosclerosis. Having achieved that, a more targeted therapy that would aim to raise either HDL functionality or to remodel HDL structure would be more easily designed.

Association between Paraoxonase 1 (PON1) Polymorphisms and the Risk of Acute Coronary Syndrome in a North African Population

The purpose of the present study was to investigate the distribution of PON1 Q192R and L55M polymorphisms and activities in a North African population and to determine their association with cardiovascular complications. The prevalence of the QQ, QR, RR, LL, LM, and MM genotypes in the study population was 55.4%, 34.09%, 9.83%, 41.97%, 48.20%, and 9.83% respectively. The Q, R, L, and M alleles had a gene frequency of 0.755, 0.245, 0.67, and 0.33, respectively. The PON1 192 RR genotype was significantly more prevalent among ACS patients than among healthy subjects. There was a 4.33-fold increase in the risk of ACS in subjects presenting the PON1 192 RR genotype compared to those with the QQ genotype (OR=4.33; 95% CI=1.27–17.7). There was a significantly different distribution of PON1 L55M in the ACS patient groups (UA, STEMI, NSTEMI). Moreover, individuals presenting the PON1 55MM genotype present a higher risk for ACS than those with LL genotype (OR=3.69; 95% CI=1.61–11.80). Paraoxonase activities were significantly lower in coronary patients than in healthy subjects. The decrease in PON1 activity was inversely correlated with the number of concomitant risk factors for CVD (r=0.57, p<0.0001). The results of the present study suggested that the PON1 R and M alleles may play a role in the pathogenesis of cardiac ischemia in our North African population and that a decrease in PON1 activity may be a valuable marker for monitoring the development of the atherosclerosis process and the associated cardiovascular complications.

Effects of Myeloperoxidase-Induced Oxidation on Antiatherogenic Functions of High-Density Lipoprotein

High-density lipoprotein (HDL) has protective effects against the development of atherosclerosis; these effects include reverse cholesterol transport, antioxidant ability, and anti-inflammation. Myeloperoxidase (MPO) secreted by macrophages in atherosclerotic lesions generates tyrosyl radicals in apolipoprotein A-I (apoA-I) molecules, inducing the formation of apoA-I/apoA-II heterodimers through the tyrosine-tyrosine bond in HDL. Functional characterization of HDL oxidized by MPO could provide useful information about the significance of apoA-I/apoA-II heterodimers measurement. We investigated the effects of MPO-induced oxidation on the antiatherogenic functions of HDL as described above. The antioxidant ability of HDL, estimated as the effect on LDL oxidation induced by copper sulfate, was not significantly affected after MPO oxidation. HDL reduced THP-1 monocyte migration by suppressing the stimulation of human umbilical vein endothelial cells induced by lipopolysaccharide (LPS). MPO-oxidized HDL also showed inhibition of THP-1 chemotaxis, but the extent of inhibition was significantly attenuated compared to intact HDL. MPO treatment did not affect the cholesterol efflux capacity of HDL from [³H]-cholesterol-laden macrophages derived from THP-1 cells. The principal effect of MPO oxidation on the antiatherogenic potential of HDL would be the reduction of anti-inflammatory ability, suggesting that measurement of apoA-I/apoA-II heterodimers might be useful to estimate anti-inflammatory ability of HDL.

Immunohistochemical analysis of paraoxonases and chemokines in arteries of patients with peripheral artery disease

Oxidative damage to lipids and lipoproteins is implicated in the development of atherosclerotic vascular diseases, including peripheral artery disease (PAD). The paraoxonases (PON) are a group of antioxidant enzymes, termed PON1, PON2, and PON3 that protect lipoproteins and cells from peroxidation and, as such, may be involved in protection against the atherosclerosis process. PON1 inhibits the production of chemokine (C–C motif) ligand 2 (CCL2) in endothelial cells incubated with oxidized lipoproteins. PON1 and CCL2 are ubiquitously distributed in tissues, and this suggests a joint localization and combined systemic effect. The aim of the present study has been to analyze the quantitative immunohistochemical localization of PON1, PON3, CCL2 and CCL2 receptors in a series of patients with severe PAD. Portions of femoral and/or popliteal arteries from 66 patients with PAD were obtained during surgical procedures for infra-inguinal limb revascularization. We used eight normal arteries from donors as controls. PON1 and PON3, CCL2 and the chemokine-binding protein 2, and Duffy antigen/chemokine receptor, were increased in PAD patients. There were no significant changes in C–C chemokine receptor type 2. Our findings suggest that paraoxonases and chemokines play an important role in the development and progression of atherosclerosis in peripheral artery disease.

Paraoxonase-1 enzyme activity assay for clinical samples: validation and correlation studies

BACKGROUND

Paraoxonase-1 (PON1) enzyme is reported in various types of tissues and linked to numerous pathophysiological disorders. It is a potential biomarker in many pathological conditions such as cardiovascular diseases.

MATERIAL AND METHODS

We conducted several small-scale studies to evaluate PON1 performance as affected by sample types, storage, and interferences. We also carried out short-term studies to compare the performance of the widely used PON1 assay to the similar commercially available PON1 kit assay method; sample size for the method comparison was N=40, and the number varied for other validation experiments.

RESULTS

Our studies using various types of anticoagulants show that samples collected in tubes with NaF, citrate, EDTA, clot activator, and sodium heparin have increased PON1 levels that are 49%, 24.5%, 19.8%, 11.4%, and 8%, respectively, higher compared to serum samples collected in plain tubes. However, samples collected in lithium heparin tubes demonstrated 10.4% lower PON1 levels compared to serum collected in plain tubes. Biological interference such as hemolysis has little effect on PON1 levels; however, samples spiked with lipids have shown 13% lower PON 1 levels. Our studies comparing the PON1 method commonly available for PON1 assay and a similar non-ELISA commercially available PON1 kit method showed a weak Spearman correlation coefficient of R2=0.40 for the range of 104.9-245.6 U/L.

CONCLUSIONS

The current study provides new validation data on enzyme PON1 performance. While no appreciable change was seen with storage, samples type affects the enzyme performance. Our results should encourage additional clinical studies to investigate other aspects of factors known to affect PON1 enzyme function and performance.

Exploring the role of paraoxonases in the pathogenesis of coronary artery disease: a systematic review

Paraoxonases (PON) are three enzymes (PON1, PON2 and PON3) that play a role in the organism’s antioxidant system; alterations in which are associated with diseases involving oxidative stress. In this review, we summarize the evidence of PON related to the pathogenesis of coronary artery disease (CAD) and atherosclerosis. We searched three electronic databases (PubMed, Scopus and Cochrane Database) with no date limit. All of the articles selected investigated PON enzymatic activity and/or PON gene polymorphisms. The selection focused on PON in relation to atherosclerosis, CAD and myocardial infarction. The exclusion criteria were a sample size <100 patients, non-human studies, editorials and systematic reviews without restrictions on the country of origin. With these criteria, we identified thirty-five prospective studies published between 1986 and 2014 with a total of 28,164 participants. The relationship between PON gene polymorphisms and CAD was not conclusive, but most studies support the concept that alterations in PON1 enzymatic activity levels do influence atheroma formation. Conversely, relationships between PON2 and PON3 vs. CAD have not been extensively investigated. Our review of the current data concludes that the bases of paraoxonases involvement in atherosclerosis are poorly understood and that this issue requires future comprehensive, multi-centered studies.

A high throughput biochemical fluorometric method for measuring lipid peroxidation in HDL

Current cell-based assays for determining the functional properties of high-density lipoproteins (HDL) have limitations. We report here the development of a new, robust fluorometric cell-free biochemical assay that measures HDL lipid peroxidation (HDLox) based on the oxidation of the fluorochrome Amplex Red. HDLox correlated with previously validated cell-based (r = 0.47, p<0.001) and cell-free assays (r = 0.46, p<0.001). HDLox distinguished dysfunctional HDL in established animal models of atherosclerosis and Human Immunodeficiency Virus (HIV) patients. Using an immunoaffinity method for capturing HDL, we demonstrate the utility of this novel assay for measuring HDLox in a high throughput format. Furthermore, HDLox correlated significantly with measures of cardiovascular diseases including carotid intima media thickness (r = 0.35, p<0.01) and subendocardial viability ratio (r = -0.21, p = 0.05) and physiological parameters such as metabolic and anthropometric parameters (p<0.05). In conclusion, we report the development of a new fluorometric method that offers a reproducible and rapid means for determining HDL function/quality that is suitable for high throughput implementation.

Paraoxonase responses to exercise and niacin therapy in men with metabolic syndrome

Our purpose was to characterize changes in paraoxonase 1 (PON1) activity and concentration after single aerobic exercise sessions conducted before and after 6 weeks of niacin therapy in men with metabolic syndrome (MetS). Twelve men with MetS expended 500 kcal by walking at 65% of VO2max before and after a 6-week regimen of niacin. Niacin doses were titrated by 500 mg/week from 500 to 1500 mg/day and maintained at 1500 mg/day for the last 4 weeks. Fasting blood samples were collected before and 24 hours after each exercise session and analyzed for PON1 activity, PON1 concentration, myeloperoxidase (MPO), apolipoprotein A1, oxidized low-density lipoprotein (oLDL), lipoprotein particle sizes and concentrations. PON1 activity, PON1 concentration, MPO, and oLDL were unaltered following the independent effects of exercise and niacin (P > 0.05 for all). High-density lipoprotein particle size decreased by 3% (P = 0.040) and concentrations of small very low-density lipoprotein increased (P = 0.016) following exercise. PON1 activity increased 6.1% (P = 0.037) and PON1 concentrations increased 11.3% (P = 0.015) with the combination of exercise and niacin. Exercise and niacin works synergistically to increase PON1 activity and concentration with little or no changes in lipoproteins or markers of lipid oxidation.

Cardiovascular risk in rheumatoid arthritis: recent advances in the understanding of the pivotal role of inflammation, risk predictors and the impact of treatment

Risk of cardiovascular (CV) disease is increased among RA patients. High inflammatory burden associated with RA appears to be a key driver of the increased cardiovascular risk. Inflammation is linked with accelerated atherosclerosis and associated with a paradoxical inversion of the relationship between CV risk and lipid levels in patients with untreated RA, recently coined the lipid paradox. Furthermore, the inflammatory burden is also associated with qualitative as well as quantitative changes in lipoproteins, with the anti-inflammatory and atheroprotective roles associated with high-density lipoprotein cholesterol significantly altered. RA therapies can increase lipid levels, which may reflect the normalization of lipids due to their inflammatory-dampening effects. However, these confounding influences of inflammation and RA therapies on lipid profiles pose challenges for assessing CV risk in RA patients and interpretation of traditional CV risk scores. In this review we examine the relationship between the increased inflammatory burden in RA and CV risk, exploring how inflammation influences lipid profiles, the impact of RA therapies and strategies for identifying and monitoring CV risk in RA patients aimed at improving CV outcomes.

Dietary polyphenols regulate endothelial function and prevent cardiovascular disease

Vascular endothelial cell (EC) dysfunction strongly induces development of cardiovascular and cerebrovascular diseases. Epidemiologic studies demonstrated a preventative effect of dietary polyphenols toward cardiovascular disease. In studies using cultured vascular ECs, polyphenols were recognized to regulate nitric oxide and endothelin-1 (ET-1) production. Furthermore, epigallocatechin-3-gallate inhibited the expression of adhesion molecules by a signaling pathway that is similar to that of high-density lipoprotein and involves induction of Ca(2+)/calmodulin-dependent kinase II, liver kinase B, and phosphatidylinositol 3-kinase expression. The effects of polyphenols on ECs include antioxidant activity and enhancement of the expression of several protective proteins, including endothelial nitric oxide synthase and paraoxonase 1. However, the observed effects of dietary polyphenols in vitro do not always translate to an in vivo setting. As such, there are many questions concerning their physiological mode of action. In this review, we discuss research on the effect of dietary polyphenols on cardiovascular disease and their protective effect on EC dysfunction.