Impaired paraoxonase-1 status in obese children. Relationships with insulin resistance and metabolic syndrome

Serum Arylesterase, Paraoxonase, and Lactonase Activities and Paraoxonase-1 Concentrations in Morbidly Obese Patients and Their Relationship with Non-Alcoholic Steatohepatitis

Paraoxonase-1 (PON1) is an antioxidant enzyme associated with high-density lipoproteins (HDL). Reduced serum PON1 activity is found in diseases marked by oxidative stress and inflammation, but its role in obesity remains unclear. This study investigated PON1 activities and concentrations in morbidly obese individuals and explored the impacts of the genetic polymorphism PON1 rs662 and non-alcoholic fatty liver disease on enzymatic properties. We recruited 1349 morbidly obese patients undergoing bariatric surgery and 823 non-obese volunteers. PON1-related variables, including arylesterase, paraoxonase, and lactonase activities and PON1 concentrations, were examined. Our results showed that morbidly obese individuals exhibited higher PON1 concentrations but lower enzymatic activities than non-obese individuals. We observed inverse associations of arylesterase and paraoxonase activities with waist circumference (rho = -0.24, p < 0.001, and rho = -0.30, p < 0.001, respectively) and body mass index (rho = -0.15, p = 0.001, and rho = -0.23, p < 0.001), as well as direct associations of arylesterase, paraoxonase, and lactonase activities with HDL cholesterol (rho = 0.11, p = 0.005, rho = 0.20, p < 0.001, and rho = 0.20, p < 0.001). No significant differences were observed regarding metabolic syndrome, type 2 diabetes mellitus, hypertension, dyslipidemia, rs662 polymorphism allele frequencies, or the diagnosis of non-alcoholic steatohepatitis. Nevertheless, correlations were found between certain PON1-related variables, steatosis, and ballooning. In conclusion, changes in PON1-related variables in morbidly obese patients are dependent on the disease itself and HDL levels. The relationships between these variables and specific liver histological changes raise intriguing questions for consideration in future studies.

Substrate-dependent inactivation of recombinant paraoxonase 1 during catalytic dihydrocoumarin turnover and the protective properties of surfactants

Human paraoxonase-1 (PON1) is the most studied member of the paraoxonases (PONs) family and catalyzes the hydrolysis of various substrates (lactones, aryl esters, and paraoxon). Numerous studies link PON1 to oxidative stress-related diseases such as cardiovascular disease, diabetes, HIV infection, autism, Parkinson's, and Alzheimer's, where the kinetic behavior of an enzyme is characterized by initial rates or by modern methods that obtain enzyme kinetic parameters by fitting the computed curves over the entire time-courses of product formation (progress curves). In the analysis of progress curves, the behavior of PON1 during hydrolytically catalyzed turnover cycles is unknown. Hence, progress curves for enzyme-catalyzed hydrolysis of the lactone substrate dihydrocoumarin (DHC) by recombinant PON1 (rePON1) were analyzed to investigate the effect of catalytic DHC turnover on the stability of rePON1. Although rePON1 was significantly inactivated during the catalytic DHC turnover, its activity was not lost due to the product inhibition or spontaneous inactivation of rePON1 in the sample buffers. Examination of the progress curves of DHC hydrolysis by rePON1 led to the conclusion that rePON1 inactivates itself during catalytic DHC turnover hydrolysis. Moreover, human serum albumin or surfactants protected rePON1 from inactivation during this catalytic process, which is significant because the activity of PON1 in clinical samples is measured in the presence of albumin.

Paraoxonase-1: How a xenobiotic detoxifying enzyme has become an actor in the pathophysiology of infectious diseases and cancer

Both infectious and non-infectious diseases can share common molecular mechanisms, including oxidative stress and inflammation. External factors, such as bacterial or viral infections, excessive calorie intake, inadequate nutrients, or environmental factors, can cause metabolic disorders, resulting in an imbalance between free radical production and natural antioxidant systems. These factors may lead to the production of free radicals that can oxidize lipids, proteins, and nucleic acids, causing metabolic alterations that influence the pathogenesis of the disease. The relationship between oxidation and inflammation is crucial, as they both contribute to the development of cellular pathology. Paraoxonase 1 (PON1) is a vital enzyme in regulating these processes. PON1 is an enzyme that is bound to high-density lipoproteins and protects the organism against oxidative stress and toxic substances. It breaks down lipid peroxides in lipoproteins and cells, enhances the protection of high-density lipoproteins against different infectious agents, and is a critical component of the innate immune system. Impaired PON1 function can affect cellular homeostasis pathways and cause metabolically driven chronic inflammatory states. Therefore, understanding these relationships can help to improve treatments and identify new therapeutic targets. This review also examines the advantages and disadvantages of measuring serum PON1 levels in clinical settings, providing insight into the potential clinical use of this enzyme.

Lipid-Based Nutrient Supplementation Increases High-Density Lipoprotein (HDL) Cholesterol Efflux Capacity and Is Associated with Changes in the HDL Glycoproteome in Children

Prenatal plus postnatal small-quantity lipid-based nutrient supplements (SQ-LNS) improved child growth at 18 months in the International Lipid-Based Nutrient Supplements DYAD trial in Ghana. In this secondary outcome analysis, we determined whether SQ-LNS versus prenatal iron and folic acid (IFA) supplementation improves the cholesterol efflux capacity (CEC) of high-density lipoprotein (HDL) particles and alters their lipidomic, proteomic, or glycoproteomic composition in a subset of 80 children at 18 months of age. HDL CEC was higher among children in the SQ-LNS versus IFA group (20.9 ± 4.1 vs 19.4 ± 3.3%; one-tailed p = 0.038). There were no differences in HDL lipidomic or proteomic composition between groups. Twelve glycopeptides out of the 163 analyzed were significantly altered by SQ-LNS, but none of the group differences remained significant after correction for multiple testing. Exploratory analysis showed that 6 out of the 33 HDL-associated proteins monitored differed in glycopeptide enrichment between intervention groups, and 6 out of the 163 glycopeptides were correlated with CEC. We conclude that prenatal plus postnatal SQ-LNS may modify HDL protein glycoprofiles and improve the CEC of HDL particles in children, which may have implications for subsequent child health outcomes. This trial was registered at clinicaltrials.gov as NCT00970866.

On the Role of Paraoxonase-1 and Chemokine Ligand 2 (C-C motif) in Metabolic Alterations Linked to Inflammation and Disease. A 2021 Update

Infectious and many non-infectious diseases share common molecular mechanisms. Among them, oxidative stress and the subsequent inflammatory reaction are of particular note. Metabolic disorders induced by external agents, be they bacterial or viral pathogens, excessive calorie intake, poor-quality nutrients, or environmental factors produce an imbalance between the production of free radicals and endogenous antioxidant systems; the consequence being the oxidation of lipids, proteins, and nucleic acids. Oxidation and inflammation are closely related, and whether oxidative stress and inflammation represent the causes or consequences of cellular pathology, both produce metabolic alterations that influence the pathogenesis of the disease. In this review, we highlight two key molecules in the regulation of these processes: Paraoxonase-1 (PON1) and chemokine (C-C motif) ligand 2 (CCL2). PON1 is an enzyme bound to high-density lipoproteins. It breaks down lipid peroxides in lipoproteins and cells, participates in the protection conferred by HDL against different infectious agents, and is considered part of the innate immune system. With PON1 deficiency, CCL2 production increases, inducing migration and infiltration of immune cells in target tissues and disturbing normal metabolic function. This disruption involves pathways controlling cellular homeostasis as well as metabolically-driven chronic inflammatory states. Hence, an understanding of these relationships would help improve treatments and, as well, identify new therapeutic targets.

Clinical Performance of Paraoxonase-1-Related Variables and Novel Markers of Inflammation in Coronavirus Disease-19. A Machine Learning Approach

SARS-CoV-2 infection produces a response of the innate immune system causing oxidative stress and a strong inflammatory reaction termed ‘cytokine storm’ that is one of the leading causes of death. Paraoxonase-1 (PON1) protects against oxidative stress by hydrolyzing lipoperoxides. Alterations in PON1 activity have been associated with pro-inflammatory mediators such as the chemokine (C-C motif) ligand 2 (CCL2), and the glycoprotein galectin-3. We aimed to investigate the alterations in the circulating levels of PON1, CCL2, and galectin-3 in 126 patients with COVID-19 and their interactions with clinical variables and analytical parameters. A machine learning approach was used to identify predictive markers of the disease. For comparisons, we recruited 45 COVID-19 negative patients and 50 healthy individuals. Our approach identified a synergy between oxidative stress, inflammation, and fibrogenesis in positive patients that is not observed in negative patients. PON1 activity was the parameter with the greatest power to discriminate between patients who were either positive or negative for COVID-19, while their levels of CCL2 and galectin-3 were similar. We suggest that the measurement of serum PON1 activity may be a useful marker for the diagnosis of COVID-19.

Paraoxonase-1 (PON1) Status Analysis Using Non-Organophosphate Substrates

Human paraoxonase-1 (PON1) is a high-density lipoprotein-associated enzyme with antioxidant, anti-inflammatory, and antiapoptotic roles. The ability of PON1 to hydrolyze specific organophosphate (OP) compounds and prevent accumulation of oxidized lipids in lipoproteins has prompted a large number of studies investigating PON1's role in modulating toxicity and disease. Most of these studies, however, have only focused on PON1 single nucleotide polymorphism analyses and have ignored PON1 activity levels, arguably the most important parameter in determining protection against exposure and disease. We developed a two-substrate activity assay termed "PON1 status" that reveals both the functional PON1₁₉₂ genotype and plasma PON1 activity levels. While our previous studies with PON1 status demonstrated that both PON1₁₉₂ functional genotype and enzymatic activity levels obtained exclusively by determining PON1 status are required for a proper evaluation of PON1's role in modulating OP exposures and risk of disease, the original PON1 status assay requires the use of highly toxic OP metabolites. As many laboratories are not prepared to handle such toxic compounds and the associated waste generated, determination of PON1 status has been limited to rather few studies. Here, we describe a PON1 status protocol that uses non-OP substrates with a resolution equivalent to that of the original PON1 status approach. We have also included useful suggestions to ensure the assays can easily be carried out in any laboratory. The protocols described here will enable a proper examination of the risk of exposure or susceptibility to disease in PON1 epidemiological studies without the need to handle highly toxic substrates. © 2021 Wiley Periodicals LLC. Basic Protocol: Determining PON1 status using non-organophosphate substrates Support Protocol 1: Experimental pathlength determination Support Protocol 2: PON1 DNA genotyping for the Q192R (rs662) polymorphism.

A Multi-Omics Analysis of PON1 Lactonase Activity in Relation to Human Health and Disease

Paraoxonase 1 (PON1) enzyme has antioxidative properties and is present in mammalian blood and several other body fluids. In blood, PON1 is usually integrated into the high-density lipoprotein (HDL) cholesterol. PON1 is a highly versatile enzyme displaying diverse functions such as arylesterase, lactonase, and paraoxonase, among others. PON1 activities are usually investigated with artificial substrates, for example, dihydrocoumarin and thiobutyl butyrolactone for lactonase activity. The PON1 enzyme activities measured with different substrates tend to be falsely assumed as being equivalent in the literature, although there are poor or weak correlations among the PON1 enzyme activities with different substrates. In addition, and despite our knowledge of the factors influencing PON1 paraoxonase and arylesterase activities, there is little knowledge of PON1 lactonase activity variations and attendant mechanisms. This is important considering further that the lactonase activity is the native activity of PON1. We report here a multi-omics analysis of PON1 lactonase activity. The influence of genetic variations, particularly of single nucleotide polymorphisms and epigenetic, proteomic, and lipidomic variations on PON1 lactonase activity are reviewed. In addition, the influence of various environmental, clinical, and demographic variables on PON1 lactonase activity is discussed. Finally, we examine the associations between PON1 lactonase activity and health states and common complex diseases such as atherosclerosis, dementias, obesity, and diabetes. To the best of our knowledge, this is the first multi-omics analysis of PON1 lactonase activity with an eye to future applications in basic life sciences and translational medicine and the nuances of critically interpreting PON1 function with lactones as substrates.

Anti-Inflammatory and Antioxidant Effects of Regular Consumption of Cooked Ham Enriched with Dietary Phenolics in Diet-Induced Obese Mice

Oxidative damage and chronic inflammation have been proven as one of the major factors associated with obesity, which increases the incidence of non-communicable chronic diseases. In this sense, the development of new functional products aiming at the palliation of oxidative stress and inflammatory disruption can be a determining factor for public health as seen in previous researches. In this study, a blend of potentially bioavailable dietary phenolics was added to low sodium and low-fat cooked ham. A diet-induced obesity model in C57/BL6J mice has been used for testing the effectiveness of the phenolic blend and the new functionalized product, which bioavailability was tested by UPLC-ESI-QTOF-MS. After obesity induction, different oxidative and inflammatory biomarkers were evaluated. Results in the murine induced obesity model, demonstrate a robust statistically significant improvement in key parameters related with obesity risk in the groups feed with a phenolic-enriched diets (P) + high-fat diet (HFD) and phenolic enriched cooked ham (PECH) + HFD. In both groups there was an improvement in body composition parameters, inflammatory biomarkers and antioxidant enzymes levels. Specifically in the group feed with the phenolic enriched cooked ham (PECH + HFD) there was an improvement of total fat volume (23.08% reduction), spleen index (22.04% of reduction), plasmatic MCP-1 (18% reduction), IL-6 (38.94% reduction), IL-10 (13.28% reduction), TNF-α (21.32% reduction), gut IL-1β (10.86% reduction), gut IL-6 (13.63% reduction) and GPx (60.15% increase) and catalase (91.37% increase) enzymes. Thus, the functionalized ham could be considered an appropriate dietary polyphenol source, which might improve the oxidative and inflammatory status and could finally result in the potential decrease of the risk of certain non-communicable chronic diseases.

Some indazoles reduced the activity of human serum paraoxonase 1, an antioxidant enzyme: in vitro inhibition and molecular modeling studies

Background: Paraoxonase 1 (PON1: EC 3.1.8.1) is a vital antioxidant enzyme against mainly atherosclerosis and many other diseases associated with oxidative stress. Thus, studies related to PON1 have an important place in the pharmacology. In this study, we aimed to evaluate the in vitro inhibition effects of some indazoles on the activity of human PON1. Methods: PON1 was purified from human serum with a specific activity of 5000 U/mg and 13.50% yield by using simple chromatographic methods. Results: The indazoles showed K_i values in a range of 26.0 ± 3.00-111 ± 31.0 μM against hPON1. All these indazoles exhibited competitive inhibition. In addition, molecular docking studies were performed in order to assess the probable binding mechanisms into the active site of hPON1. Molecular modeling studies confirmed our results. Conclusions: Inhibition of PON1 by indazoles supplies a verification to further consideration of limitation dosage of indazole molecule groups as drug.

The Effects of Anthocyanins and Their Microbial Metabolites on the Expression and Enzyme Activities of Paraoxonase 1, an Important Marker of HDL Function

High circulating HDL concentrations and measures of various HDL functions are inversely associated with cardiovascular disease (CVD) risk. Paraoxonase 1 (PON1) contributes to many of the athero-protective functions of HDL, such as promoting the reverse cholesterol transport process and reducing the levels of oxidized LDL. PON1 activities are influenced by several factors, the most important being diet and genetic polymorphisms. Reported data from randomized controlled trials have shown that anthocyanin consumption increased PON1 activity. However, the underlying molecular mechanisms by which anthocyanins increase PON1 activity are not understood. Therefore, the aim of this research was to investigate the ability of anthocyanins and their metabolites to increase PON1 gene expression and/or enzyme activities as potential mechanisms. The effect of the two predominant dietary anthocyanins and 18 of their recently identified microbial metabolites including their phase-II conjugates on PON1 gene expression was studied using a PON1-Huh7 stably-transfected cell line and reporter gene assay. The effects of these compounds on PON1 arylesterase and lactonase activities were investigated using two isoforms of the PON1 enzyme that are the phenotypes of the 192Q/R polymorphism. None of the compounds caused even modest changes in PON1 promoter activity (p ≥ 0.05). Further, none of the compounds at physiological concentrations caused any significant changes in the arylesterase or lactonase activity of either of the iso-enzymes. Cyanidin reduced the lactonase activity of the PON1-R192R enzyme at high concentrations (−22%, p < 0.001), but not at physiologically achievable concentrations. In conclusion, none of the data reported here support the notion that anthocyanins or their metabolites affect PON1 transactivation or enzyme activities.

Sex difference: an important issue to consider in epidemiological and clinical studies dealing with serum paraoxonase-1

The aim of this study was to evaluate the influence of sex on serum paraoxonase-1 (PON1) activities and on its relationship with cardiovascular disease risk factors such as overall and central obesity. Arylesterase and lactonase activities of PON1 were assessed in 374 women and 92 men. Both arylesterase and lactonase activities were significantly higher in women compared to men (p<0.001), irrespectively of confounders such as high density lipoprotein-cholesterol, age, smoking and body mass index or waist circumference. Sex also strongly influenced the interplay between PON1 and both fat measures, with only the arylesterase showing a significant and independent inverse correlation with the former parameter (r = -0.248, p<0.001) and the risk of overall obesity (odds ratio: 0.559, 95% confidence interval: 0.340-0.919) in women, but not in men; conversely, neither of the two activities remained associated with waist circumference in men or women after full adjustment. Noteworthy, the association between arylesterase and BMI in the female subsample was significant among women younger than forty-five years (r = -0.453, p<0.001, R ² = 0.207). In conclusion, our study suggests that sex might chiefly influence PON1 activity and its contribution to cardiovascular disease risk. Further studies are needed to confirm and clarify our preliminary findings.

Genotypes of Common Polymorphisms in the PON1 Gene Associated with Paraoxonase Activity as Cardiovascular Risk Factor

BACKGROUND

Paraoxonase-1(PON1) exhibits hydrolytic activity and prevents the oxidation of high and low-density lipoproteins. Polymorphisms in the PON1 gene have been associated with variations in paraoxonase activity and with the risk of coronary artery disease (CAD).

AIM OF THE STUDY

This study analyzed the association between the frequencies of genotypes of the L55 M and Q192 R SNPs in the PON1 gene with the PON1 activity and with CAD risk factors.

METHODS

Women, determined by body composition, biochemical markers, and arylesterase (AREase) and paraoxonase (CMPase) activities were studied. Genotyping of L55 M and Q192 R polymorphisms was performed by TaqMan. Seventeen studies were used in the meta-analysis.

RESULTS

A significant decrease in PON1 activity in carrying the LM/MM and QQ genotypes is identified, correlations are found between the AREase activity with glucose, cholesterol and atherogenic risk index. Carriers of the LM or MM genotype were related with obesity (OR = 1.6; p = 0.039), and the MQ haplotype has an effect on the decrease in AREase (β = ‒22.4; p <0.001) and CMPase (β = ‒3.8; p <0.001). In addition, a lower proportion of Native American admixture was observed in women with LM or MM genotype, while it was higher for the European proportion compared with the LL genotype (p <0.001).

CONCLUSIONS

The LL-L55 M and QR-Q192 R genotypes are identified as the most frequently in the different states or cities of the country, and genotypic proportions are different, probably depending on the genetic structure of the populations. The association that is reported more frequently in the different studies is with enzymatic activity.

Sex difference: an important issue to consider in epidemiological and clinical studies dealing with serum paraoxonase-1

The aim of this study was to evaluate the influence of sex on serum paraoxonase-1 (PON1) activities and on its relationship with cardiovascular disease risk factors such as overall and central obesity. Arylesterase and lactonase activities of PON1 were assessed in 374 women and 92 men. Both arylesterase and lactonase activities were significantly higher in women compared to men (p<0.001), irrespectively of confounders such as high density lipoprotein-cholesterol, age, smoking and body mass index or waist circumference. Sex also strongly influenced the interplay between PON1 and both fat measures, with only the arylesterase showing a significant and independent inverse correlation with the former parameter (r = −0.248, p<0.001) and the risk of overall obesity (odds ratio: 0.559, 95% confidence interval: 0.340–0.919) in women, but not in men; conversely, neither of the two activities remained associated with waist circumference in men or women after full adjustment. Noteworthy, the association between arylesterase and BMI in the female subsample was significant among women younger than forty-five years (r = −0.453, p<0.001, R² = 0.207). In conclusion, our study suggests that sex might chiefly influence PON1 activity and its contribution to cardiovascular disease risk. Further studies are needed to confirm and clarify our preliminary findings.

Exogenous (Pomegranate Juice) or Endogenous (Paraoxonase1) Antioxidants Decrease Triacylglycerol Accumulation in Mouse Cardiovascular Disease-Related Tissues

The polyphenol-rich pomegranate juice (PJ) and the high-density lipoprotein (HDL)-associated paraoxonase1 (PON1) are known as potent atheroprotective antioxidants, but their effects on other tissues related to cardiovascular disease (CVD) remain unknown. The current study aimed to investigate the effects of treating mice with PJ or recombinant PON1 (rePON1) on the oxidation and lipid status of CVD-related tissues: serum, aorta, heart, liver, kidney, visceral, and subcutaneous adipose tissues (VAT and SAT). Both PJ consumption and rePON1 injection decreased the serum levels of thiobarbituric acid-reactive substances (16% and 19%) and triacylglycerols (TAG, 24% and 27%), while only rePON1 increased the levels of thiol groups (35%) and decreased serum cholesterol (15%). Both PJ and rePON1 significantly decreased aortic cholesterol (38% and 32%) and TAG (62% and 58%) contents in association with downregulation of the key TAG biosynthetic enzyme diacylglycerol O-acyltransferase 1 (DGAT1, 71% and 65%), while only PJ decreased aortic lipid peroxides (47%). Substantial TAG-lowering effects of both PJ and rePON1 were observed also in the heart (31% and 42%), liver (34% and 42%), and kidney (42% and 57%). In both VAT and SAT, rePON1 decreased the levels of lipid peroxides (28% and 25%), while PJ decreased the TAG content (22% and 18%). Ex vivo incubation of SAT with serum derived from mice that consumed PJ or injected with rePON1 decreased SAT lipid peroxides (35% or 28%) and TAG mass (12% or 10%). These novel findings highlight potent TAG-lowering properties of exogenous (PJ) and endogenous (PON1) antioxidants in tissues associated with CVD.

Evaluating the link between Paraoxonase-1 levels and Alzheimer's disease development

At present, the etiopathogenesis of Alzheimer's disease (AD), the most common form of dementia, remains far to be fully deciphered. In the recent years, also the centrality of amyloid-β peptide in the pathogenesis of the neurodegenerative disease has been questioned and other hypotheses have been advanced. Notably, a common denominator of many of these theoretical models is represented by oxidative stress, which is widely proposed to play a role in the disease initiation and/or progression. Paraoxonase 1 (PON1) is a high-density lipoprotein (HDL)-associated enzyme that endows its carrier with multiple biological functions, including the ability to contrast oxidative damage to lipid components of lipoproteins and cells and protect from toxicity of specific organophosphorus pesticides. The peculiar multi-functionality nature of PON1 might be the key for explaining the vast epidemiological data showing a close association between low serum PON1 activity and risk of several diseases, including cardiovascular and neurodegenerative diseases, in particular AD. In this review, we discuss the possible link between PON1 with AD pathogenesis and we hypothesize eventual mechanistic pathways that could account from epidemiological observations. We also highlight the methodological issue limitation in PON1 studies that still impede to give a definitive and certain picture of its effective biological impact on human health including AD.

Effect of continuous renal-replacement therapy on paraoxonase-1-related variables in patients with acute renal failure caused by septic shock

BACKGROUND

Acute renal failure in patients with sepsis is associated with high mortality. Studies have highlighted alterations in serum paraoxonase-1 in severe infections. However, the published literature has no insight into the clinical evolution of these parameters in patients with sepsis and acute renal failure treated with extra-renal depuration techniques.

METHODS

We studied 25 patients with sepsis and acute renal failure who were treated with continuous renal-replacement therapy. Blood for laboratory analyses was collected at days 0, 1, 2, 5, 7, and 10. We measured serum paraoxonase-1 activity and concentration, lipid profile, aminotransferase activities, pH, and lactate, urea, creatinine and C-reactive protein concentrations. Values were compared with those of 50 healthy individuals.

RESULTS

Patients with sepsis and acute renal failure had lower serum paraoxonase-1 activity, lower high-density lipoprotein cholesterol concentrations, and higher serum paraoxonase-1 concentrations than the control group. We found a significant inverse correlation between serum paraoxonase-1 concentrations and the Acute Physiology And Chronic Health Evaluation II score in survivors as well as non-survivors, and a significant inverse correlation between serum paraoxonase-1 concentrations and the Sequential Organ Failure Assessment score only in survivors. Extra-renal depuration techniques produced a further increase in this enzyme related to the duration of treatment, and to serum urea concentration.

CONCLUSION

Our results show an inverse relationship between the concentration of paraoxonase-1 and the disease severity of patients with renal failure caused by septic shock. These results highlight relationships between paraoxonase-1 and infectious diseases and sepsis, with insights into potential clinical evolution of treatment.

Relation of Paraoxonase 1 Activity with Biochemical Variables, Brachial Artery Intima-Media Thickness in Patients with Diabetes with or without Obesity

AIM

The sodium-sparing effect of insulin leads to increase in total sodium pool of the body which is a chronic stimulus for atrial natriuretic peptide (ANP). In our study we aimed to determine the relationship between ANP and microvascular complications of diabetes.

METHODS

60 patients, 30-70 years old, with the diagnosis of type 2 diabetes mellitus (DM) are enrolled into the study. Patients with a chronic disease other than DM are excluded. Blood samples for routine biochemical tests are taken after at least 12 h fasting at 8-9 am. Blood samples for glucose and insulin levels are taken 2 h after a standard meal. Blood tubes with EDTA are used for ANP levels. The microvascular complications of the patients are evaluated.

RESULTS

32 of the patients had microvascular complications. Age, BMI, waist and hip circumferences, and ANP levels were significantly higher in the group with microvascular complications. There were no significant differences in waist-to-hip ratio, blood glucose, HbA1c, fasting insulin, postprandial insulin, fasting HOMA, postprandial HOMA as well as sodium, potassium, magnesium, calcium and lipid levels between the two groups. When the relationship between ANP and obesity, retinopathy, neuropathy, nephropathy, diabetes time, HbA1c, or sex are evaluated separately, the only significant parameters related to ANP were obesity and retinopathy.

CONCLUSION

In our study we have found that there was a significant relationship between ANP levels and microvascular complications of diabetes. Future studies are needed to show if ANP is the stimulus of microvascular complication development/progression or only an epiphenomenon.

Paraoxonase, arylesterase and lactonase activities of paraoxonase-1 (PON1) in obese and severely obese women

Obesity is independently associated with disturbances in lipid and lipoprotein metabolism, oxidative stress, and is a well-established independent risk factor for cardiovascular diseases (CVD). Human paraoxonase 1 (PON1) is a pleotropic high-density lipoprotein (HDL)-associated enzyme with antioxidant and anti-inflammatory proprieties that have been suggested to contribute to the athero-protective function of the lipoprotein. The aim of this study was to investigate whether obesity is associated with PON1 activity and whether this association is influenced by oxidative stress, inflammation and HDL cholesterol (HDL-C) concentration. The promiscuous activities, arylesterase and paraoxonase, and the putative physiological activity, lactonase, of PON1 were assessed in the serum of 214 obese and severely obese, 101 overweight and 129 normal-weight women. Levels of high-sensitivity C-reactive protein (hs-CRP), hydroperoxides (by-products of lipid oxidative damage) and lipid profiles were also evaluated. Arylesterase activity was the only activity that significantly differed across the groups (ANOVA, p < .01), with the greatest decrease observed in individuals with body mass index (BMI) > 40 kg/m² compared to controls (p < .001). This activity was also inversely, although weakly (r = -0.160, p < .001) correlated with the BMI, and the association was independent of age and levels of oxidative stress and inflammation, but not of HDL-C concentration. In conclusion, our results suggest that the apparent obesity-associated decrement of PON1 activity might simply reflect the decrease in concentration of its plasmatic carrier.

Influence on serum asymmetric dimethylarginine (ADMA) concentrations of human paraoxonase 1 polymorphism (Q192R) and exposure to polycyclic aromatic hydrocarbons (PAHs) in Mexican women, a gene-environment interaction

It has been demonstrated that Cardiovascular Diseases (CVD) are a consequence of the combination of genetic and environmental factors and/or the interaction between them. Therefore, the aim of this study was to evaluate the impact of polycyclic aromatic hydrocarbon (PAHs) exposure and PON1 Q192R polymorphism (genetic susceptibility) on serum asymmetric dimethylarginine (ADMA) levels in Mexican women (n = 206). Urinary 1-hydroxypyrene concentrations (1-OHP; exposure biomarker for PAHs) were quantified using a high-performance liquid chromatography technique, PON1 Q192R polymorphism was genotyped using TaqMan probes and serum ADMA concentrations were evaluated using a commercially available ELISA kit. Urinary 1-OHP levels detected in this study ranged from 0.07 to 9.37 μmol/mol of creatinine (0.13-18.0 μg/g of creatinine). Regarding allele frequency (PON1 Q192R polymorphism), the 192Q-allele frequency was 0.43 and for the 192R-allele it was 0.57. In relation to serum ADMA levels, the levels ranged from 0.06 to 1.46 μmol/L. Moreover, multiple linear regression analysis was performed and associations between urinary 1-OHP levels (β = 0.05, p = 0.002), PON1 Q192R polymorphism (β = 0.04, p = 0.003) and serum ADMA concentrations were found. Besides, an interaction (gene-environment interaction) of both independent variables (1-OHP and PON1 polymorphism) on serum ADMA levels was found (β = 0.04, p = 0.02) in the constructed multiple linear model. Therefore, according to the significance of this research, it is necessary to execute health programs to reduce cardiovascular risk in the assessed population.

Biochemical indices of oxidative stress and inflammation in the evaluation of peripheral artery disease

BACKGROUND

The aims of this study were: (1) to investigate changes in indices of oxidative stress and inflammation in the evaluation of peripheral artery disease (PAD); (2) to compare the diagnostic efficacy of these parameters with that of classical clinical laboratory routine parameters.

DESIGN AND METHODS

We studied 115 patients with PAD and 300 healthy volunteers.

RESULTS

PAD patients had significantly increased circulating concentrations of F2-isoprostanes, protein carbonyls, chemokine (C-C motif) ligand 2 (CCL2), high-sensitivity C-reactive protein (hs-CRP), β-2-microglobulin (B2M), and decreased paraoxonase-1 (PON1) levels. When patients were classified according to the Fontaine score, we observed important increases in plasma F2-isoprostanes and CCL2 that appeared in milder stages of the disease, and remained so at similar levels in more advanced stages; almost no overlapping with the control group was noted. Receiver operating characteristics analysis comparing patients and controls revealed that the areas under the curve for F2-isoprostanes and CCL2 approached unity [0.999 (0.998-1.000) and 0.993 (0.985-1.000)], respectively, and significantly higher to those of the other measured parameters.

CONCLUSION

Our data suggest that F2-isoprostanes and CCL2 measurements may be useful tools for the diagnosis of PAD.

Paraoxonases-1, -2 and -3: What are their functions?

Paraoxonase-1 (PON1), an esterase/lactonase primarily associated with plasma high-density lipoprotein (HDL), was the first member of this family of enzymes to be characterized. Its name was derived from its ability to hydrolyze paraoxon, the toxic metabolite of the insecticide parathion. Related enzymes PON2 and PON3 were named from their evolutionary relationship with PON1. Mice with each PON gene knocked out were generated at UCLA and have been key for elucidating their roles in organophosphorus (OP) metabolism, cardiovascular disease, innate immunity, obesity, and cancer. PON1 status, determined with two-substrate analyses, reveals an individual's functional Q192R genotype and activity levels. The three-dimensional structure for a chimeric PON1 has been useful for understanding the structural properties of PON1 and for engineering PON1 as a catalytic scavenger of OP compounds. All three PONs hydrolyze microbial N-acyl homoserine lactone quorum sensing factors, quenching Pseudomonas aeruginosa's pathogenesis. All three PONs modulate oxidative stress and inflammation. PON2 is localized in the mitochondria and endoplasmic reticulum. PON2 has potent antioxidant properties and is found at 3- to 4-fold higher levels in females than males, providing increased protection against oxidative stress, as observed in primary cultures of neurons and astrocytes from female mice compared with male mice. The higher levels of PON2 in females may explain the lower frequency of neurological and cardiovascular diseases in females and the ability to identify males but not females with Parkinson's disease using a special PON1 status assay. Less is known about PON3; however, recent experiments with PON3 knockout mice show them to be susceptible to obesity, gallstone formation and atherosclerosis. Like PONs 1 and 2, PON3 also appears to modulate oxidative stress. It is localized in the endoplasmic reticulum, mitochondria and on HDL. Both PON2 and PON3 are upregulated in cancer, favoring tumor progression through mitochondrial protection against oxidative stress and apoptosis.

Paraoxonases, mitochondrial dysfunction and non-communicable diseases

The most common non-communicable diseases (NCD) are obesity, cardiovascular disease, diabetes, cancer, chronic respiratory diseases, and neurological diseases. Together, they constitute the commonest cause of death and disability worldwide. Mitochondrial alterations, oxidative stress and inflammation underpin NCD and are molecular mechanisms playing major roles in the disease onset and natural history. Interrelations between the mechanisms of oxidative stress, inflammation and metabolism are, in the broadest sense of energy transformations, being increasingly recognized as part of the problem in NCD. Whether or not oxidative stress and inflammation are the causes or the consequences of cellular disturbances, they do significantly contribute to NCD. Paraoxonases are associated with mitochondria and mitochondria-associated membranes. They modulate mitochondria-dependent superoxide production, and prevent apoptosis. Their overexpression protects mitochondria from endoplasmic reticulum stress and subsequent mitochondrial dysfunction; highlighting that the anti-inflammatory effects of paraoxonases may be mediated, at least in part, by their protective role in mitochondria and associated organelle function. Since oxidative stress is implicated in the development of NCD (as a result of mitochondrial dysfunction), these data suggest that understanding the role and the molecular targets of paraoxonases may provide novel strategies of intervention in the treatment of these important diseases.

Strawberries Added to the Usual Diet Suppress Fasting Plasma Paraoxonase Activity and Have a Weak Transient Decreasing Effect on Cholesterol Levels in Healthy Nonobese Subjects

OBJECTIVE

Strawberries can improve oxidants-antioxidants balance and reduce some cardiovascular risk factors in obese subjects. Paraoxonase-1 (PON-1) is a high-density lipoprotein-associated enzyme with antioxidant properties that can protect from coronary artery disease in humans. We examined the effect of strawberry consumption on plasma PON-1 activity and lipid profile in healthy nonobese subjects.

METHODS

Thirty-one subjects (body mass index [BMI] 24.4 ± 4.0 kg/m(2)) on their usual diet consumed 500 g of strawberry pulp daily for 30 days (first course) and after a 10-day washout the cycle was repeated (second course). Fasting blood and spot morning urine samples were collected before, during, and after each strawberry course (8 time points) for determination of paraoxonase and arylesterase PON-1 activities and lipid profile. Twenty subjects served as controls with respect to cholesterol and PON-1 activities changes over the study period.

RESULTS

Strawberries decreased mean plasma paraoxonase PON-1 activity and this effect was more evident after the second course (by 11.6%, p < 0.05) than after the first course (5.4%, p = 0.06), whereas arylesterase activity was constant. Strawberries altered total cholesterol levels (p < 0.05) with a tendency to transiently decrease it (by 5.1%) only after 15 days of the first course. Triglycerides and high- and low-density lipoprotein cholesterol did not change in response to fruit consumption. No changes in PON-1 activities and lipid profile were noted in controls. Paraoxonase correlated with arylesterase activity (ƿ from 0.33 to 0.46 at the first 7 time points, p < 0.05). This association disappeared at the end of study (ƿ = 0.07) when the strongest inhibition of paraoxonase was noted.

CONCLUSIONS

Supplementation of the usual diet with strawberries decreased paraoxonase PON-1 activity and did not improve lipid profiles in healthy nonobese subjects. Further studies are necessary to establish the clinical significance of paraoxonase suppression and to define a group of healthy subjects who can benefit from strawberry consumption with respect to cholesterol levels.

Recent progress in the genetics and epigenetics of paraoxonase: why it is relevant to children's environmental health

PURPOSE OF REVIEW

Children are more susceptible to exposures in utero and during early childhood that may result in developmental problems and chronic diseases. Novel discoveries in the field of molecular epidemiology that can help explain susceptibility to exposures and disease will be demonstrated using the multifunctional enzyme paraoxonase 1 (PON1) as an example.

RECENT FINDINGS

The broad PON1 variability in humans, partly due to differences in genetics and age, can confer differential susceptibility because this enzyme can detoxify organophosphate pesticides and has antioxidant properties. Epigenetics plays a significant role in the mediation of the effects of environmental exposure on human health and is hypothesized to be a major contributing factor to the early-life origins of adult disease. Studies highlighted in this review demonstrate the relationship of PON1 polymorphisms with microRNA binding in addition to a link between DNA methylation in the transcriptional regulatory region with changes in PON1 enzyme levels. Other important methodologies such as ancestry informative markers and lactonase activity can enhance studies involving PON1.

SUMMARY

This PON1 model demonstrates that integrating genetic and epigenetic factors, as well as other novel methodologies, can improve our understanding of important susceptibility factors linked to pediatric disease.

Left ventricular mass and diastolic function in obese children and adolescents

BACKGROUND

Our aims were to assess left ventricular structure and diastolic function in obese subjects stratified according to ambulatory blood pressure status, and to investigate independent predictors of the left ventricular mass (LVM) index.

METHODS

Obese subjects aged 9-19 years referred for ambulatory blood pressure monitoring (ABPM) were evaluated in the cross-sectional study. In addition to biochemical and anthropometric measurements, subjects underwent ABPM, Doppler echocardiography, and treadmill exercise test.

RESULTS

According to ABPM results, 103 subjects with obesity (mean age 14.1 ± 2 years) were split in two groups: 49 hypertensive, and 54 without hypertension. Left ventricular hypertrophy was found in 16.3 % of hypertensive, and 5.6 % of normotensive. Variables included in stepwise regression analysis as potential determinants of LVM index were age, body mass index z score, waist circumference, peak systolic blood pressure on exercise test, 24-h heart rate, and night heart rate. Peak systolic blood pressure (adjusted R(2) = 0.051, β = 0.245, p = 0.013) remained as the independent predictor of LVM index. Diastolic function evaluated by mitral E/A ratio was decreased in both obese groups.

CONCLUSIONS

Early markers of cardiac disease including hypertrophy and diastolic dysfunction of the left ventricle are present in youths with obesity prior to the development of sustained hypertension.

Blood inorganic mercury is directly associated with glucose levels in the human population and may be linked to processed food intake

Background:

The goals of the study were (1) to determine the impact of inorganic mercury exposure on glucose homeostasis; and (2) to evaluate the effectiveness of two community-based interventions in promoting dietary changes among American Indian college students to reduce risk factors for Type-2 Diabetes including fasting glucose, insulin, and mercury levels, weight, and body mass index.

Methods:

To accomplish goal one, the National Health and Nutrition Examination Survey (NHANES) dataset was analyzed using a previously published method to determine if there is a relationship between inorganic blood mercury and fasting glucose. To accomplish goal two, ten college students were recruited and randomly assigned to a group receiving the online macroepigenetics nutrition course and the support group for eliminating corn sweeteners. Participants in both groups were assessed for diet patterns, weight, body mass index (BMI), fasting glucose, insulin, and mercury levels. The interventions were implemented over a 10-week period.

Results:

Analysis of the NHANES data (n=16,232) determined a direct relationship between inorganic mercury in blood and fasting glucose levels (p<0.001). The participants who took the online macroepigenetics nutrition intervention course significantly improved their diets (p<0.01), and fasting blood glucose levels (p<0.01) while having lower levels of inorganic mercury in their blood compared to the subjects in the group who eliminated corn sweeteners from their diet and participated in the support group. The trend in lower blood inorganic mercury was strong with p=0.052. The participants in the support group who eliminated corn sweeteners from their diet achieved significant weight loss (p<0.01) and reduced their body mass index (p<0.01).

Conclusion:

Total blood mercury levels may be influenced by dietary intake of highly processed foods and lower inorganic mercury levels are associated with lower fasting glucose levels. Alternative community-based interventions emphasizing the role food ingredients and toxic substances play in gene modulation and the development of diseases can result in significant dietary improvements and reductions in risk factors associated with type-2 diabetes. A healthier diet can be promoted among community members using a novel online nutrition course. Consumption of corn sweeteners may be a risk factor in the development of obesity.

Measurement of activity and concentration of paraoxonase 1 (PON-1) in seminal plasma and identification of PON-2 in the sperm of boar ejaculates

This study revealed and characterised the presence of the antioxidant enzymes paraoxonase (PON) type 1 (PON-1, extracellular) and type 2 (PON-2, intracellular) in boar semen. To evaluate PON-1, an entire ejaculate from each of ten boars was collected and the seminal plasma was harvested after double centrifugation (1,500g for 10 min). Seminal plasma was analysed for concentration as well as enzymatic activity of PON-1 and total cholesterol levels. Seminal-plasma PON-1 concentration ranged from 0.961 to 1.670 ng/ml while its enzymatic activity ranged from 0.056 to 0.400 IU/ml, which represent individual variance. Seminal-plasma PON-1 concentration and enzymatic activity were negatively correlated (r = -0.763; P < 0.01). The activity of seminal-plasma PON-1 negatively correlated with ejaculate volume (r = -0.726, P < 0.05), but positively correlated with sperm concentration (r = 0.654, P < 0.05). Total seminal-plasma cholesterol concentration positively correlated with PON-1 activity (r = 0.773; P < 0.01), but negatively correlated with PON-1 concentration (r = -0.709; P < 0.05). The presence of intracellular PON-2 was determined via immunocytochemistry in spermatozoa derived from artificial insemination. PON-2 localised to the post-acrosomal area of the sperm head and principal piece of the tail in membrane-intact spermatozoa. In summary, PON is present in boar semen, with PON-1 at low levels in seminal plasma and PON-2 within the spermatozoa. Further studies are needed to characterise the relationship between antioxidant PONs with sperm and other seminal-plasma parameters.

Introduction: oxidation and inflammation, a molecular link between non-communicable diseases

Non-communicable diseases are, by definition, those chronic diseases that are non-infectious and non-transmissible. The most common non-communicable diseases are obesity, diabetes, cancer, and cardiovascular, chronic respiratory and neurological diseases. Altogether, they are the commonest cause of death and disability in modern world. Recent investigations show that many of these diseases share common pathophysiological mechanisms and are, at least in part, different manifestations in different organs of similar molecular alterations. Mitochondrial alterations, oxidative stress and inflammation are inextricably linked and play major roles in the onset and development of non-communicable diseases. Therefore, it is conceivable that pharmacological or nutritional manipulation of oxidation and inflammation allows a significant decrease in the mortality and morbility associated to these diseases.

Serum paraoxonase/arylesterase activity and oxidative stress status in children with metabolic syndrome

OBJECTIVE

This study aimed to measure paraoxonase/arylesterase activities and to evaluate the total oxidant and antioxidant capacities in obese children and in children with metabolic syndrome (MetS).

METHODS

A total of 151 children of comparable ages (13.23±1.96 years, 13.45±1.85 years and 13.95±1.31 years) were enrolled in the study. Forty of these were children with MetS, 55 were obese and 56 were healthy controls. Diagnosis of the MetS was made according to International Diabetes Federation criteria. Paraoxonase/arylesterase activities were evaluated by using paraoxon and phenylacetate substrates. Total oxidant status (TOS) and total antioxidant status (TAS) were measured and oxidative stress index (OSI) was estimated by calculation.

RESULTS

High levels of paraoxonase were detected in the obese group, whereas high levels of arylesterase were detected in both MetS and obese groups. Higher values for TOS, TAS and OSI were found in the MetS group (p<0.05).

CONCLUSION

Higher values of mean TOS and OSI in the MetS group than those in the control groups indicate that these parameters may be indicators of future risks such as atherosclerosis in patients with MetS.

Paraoxonase (PON)1 Q192R functional genotypes and PON1 Q192R genotype by smoking interactions are risk factors for the metabolic syndrome, but not overweight or obesity

Background The metabolic syndrome (MetS) is a complex of multiple risk factors that contribute to the onset of cardiovascular disorder, including lowered levels of high-density lipoprotein (HDL) and abdominal obesity. Smoking, mood disorders, and oxidative stress are associated with the MetS. Paraoxonase (PON)1 is an antioxidant bound to HDL, that is under genetic control by functional polymorphisms in the PON1 Q192R coding sequence. Aims and methods This study aimed to delineate the associations of the MetS with plasma PON1 activity, PON1 Q192R genotypes, smoking, and mood disorders (major depression and bipolar disorder), while adjusting for HDL cholesterol, body mass index, age, gender, and sociodemographic data. We measured plasma PON1 activity and serum HDL cholesterol and determined PON1 Q192R genotypes through functional analysis in 335 subjects, consisting of 97 with and 238 without MetS. The severity of nicotine dependence was measured using the Fagerström Nicotine Dependence Scale. Results PON1 Q192R functional genotypes and PON1 Q192R genotypes by smoking interactions were associated with the MetS. The QQ and QR genotypes were protective against MetS while smoking increased metabolic risk in QQ carriers only. There were no significant associations between PON1 Q192R genotypes and smoking by genotype interactions and obesity or overweight, while body mass index significantly increased MetS risk. Smoking and especially severe nicotine dependence are significantly associated with the MetS although these effects were no longer significant after considering the effects of the smoking by PON1 Q192R genotype interaction. The MetS was not associated with mood disorders, major depression or bipolar disorder. Discussion PON1 Q192R genotypes and genotypes by smoking interactions are risk factors for the MetS that together with lowered HDL and increased body mass and age contribute to the MetS.

Paraoxonases function as unique protectors against cardiovascular diseases and diabetes: Updated experimental and clinical data

Paraoxonase (PON) refers to a family of three enzymes, namely PON1, PON2, and PON3. PON1 and PON3 are found in circulation bound to high-density lipoprotein, whereas PON2 is an intracellular protein. PON1 was first discovered as an enzyme to hydrolyze the organophosphate pesticide paraoxon, an activity that both PON2 and PON3 lack. All three PON enzymes are able to degrade oxidized lipids and protect against oxidative stress. PON enzymes also act to suppress inflammation. Animal studies show a critical role for PON enzymes, especially PON1 in protecting against cardiovascular diseases and related disorders, including diabetes and metabolic syndrome. In line with the findings in experimental animals, accumulating evidence from clinical research also indicates that PON enzymes function as potential protectors in human cardiovascular diseases and related disorders. Identification of PON enzymes as important players in cardiovascular health will facilitate the development of novel preventive and therapeutic modalities targeting PON enzymes to combat cardiovascular diseases and related disorders, which collectively constitute the chief contributors to the global burden of disease. This review describes the biochemical properties and molecular regulation of PON and summarizes the major recent findings on the functions of PON in protecting against cardiovascular diseases and related disorders.

Serum paraoxonase 1 (PON1) measurement: an update

Paraoxonase 1 (PON1) is a widely studied enzyme based on its protective role against poisoning by organophosphate (OP) metabolites of specific OP insecticides and in vascular disease, as well as its use as biomarker of diseases involving oxidative stress, inflammation and liver diseases.

This review provides an update about the current knowledge in the field of the analytical procedures that are used for PON1 measurements. It will be specially focused on: (a) characteristics of the different substrates used for measuring PON1, with emphasis in four aspects: toxicity, polymorphism influence, rate of hydrolysis and diagnostic performance. And (b) the technical aspects of PON1 assays, in which the reagents and reaction conditions, sources of variation, quality control systems, equipment and interferences with other esterases will be discussed.

The information provided in this review can contribute to a more accurate and safe measurements of PON1 in laboratories and encourage researchers to explore the wide areas of PON1 in veterinary medicine that are still unknown.

Genetics of oxidative stress in obesity

Obesity is a multifactorial disease characterized by the excessive accumulation of fat in adipose tissue and peripheral organs. Its derived metabolic complications are mediated by the associated oxidative stress, inflammation and hypoxia. Oxidative stress is due to the excessive production of reactive oxygen species or diminished antioxidant defenses. Genetic variants, such as single nucleotide polymorphisms in antioxidant defense system genes, could alter the efficacy of these enzymes and, ultimately, the risk of obesity; thus, studies investigating the role of genetic variations in genes related to oxidative stress could be useful for better understanding the etiology of obesity and its metabolic complications. The lack of existing literature reviews in this field encouraged us to gather the findings from studies focusing on the impact of single nucleotide polymorphisms in antioxidant enzymes, oxidative stress-producing systems and transcription factor genes concerning their association with obesity risk and its phenotypes. In the future, the characterization of these single nucleotide polymorphisms (SNPs) in obese patients could contribute to the development of controlled antioxidant therapies potentially beneficial for the treatment of obesity-derived metabolic complications.