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

The importance of paraoxonase 1 activity in chronic kidney disease

Paraoxonase 1 (PON1) is one of the most significant antioxidative enzymes associated with high-density lipoprotein (HDL). It has been proved that is involved in the pathogenesis of many diseases including chronic kidney disease (CKD). The association between PON1 and CKD seems to be mutual, such that the disease produces a significant decrease in PON1 activity levels, while the genetics of PON1 may affect the risk of susceptibility to CKD. Recent studies reveal that the decrease in serum PON1 activity observed in non-dialyzed and dialyzed CKD patients as well as in renal transplant (RT) patients is linked to an increased vulnerability to atherosclerosis. We intend to summarize current literature concerning PON1 activity in CKD, highlighting on the main determinants of PON1 activity, its association with oxidative stress, the impact of its genetic polymorphism on the disease development, the effect of drugs and nutritional state. Furthermore, evidence supporting the implication of reduced PON1 activity in the incident of cardiovascular disease in CKD patients, is also examined. It appears that despite the lack of standardization of PON1 activity measurement, PON1 remains a valuable biomarker for the researchers through the last decades, which contributes to the assessment of the antioxidant status having prognostic benefit on adverse clinical outcomes at various stages and etiologies of kidney disease.

The association of paraoxonase I gene polymorphisms Q192R (rs662) and L55M (rs854560) and its activity with metabolic syndrome components in fars ethnic group

OBJECTIVES

Metabolic syndrome (MetS) may cause premature development of some diseases. PON1 genes may be involved in the pathogenesis of MetS. The aim of study was to evaluate the association between Q192R and L55M gene polymorphisms and its enzyme activity with the MetS components in subjects with and without MetS.

METHODS

Polymerase Chain Reaction and Restriction Fragment Length Polymorphism analysis were performed to determine polymorphisms of the paraoxonase1 gene in subjects with and without metabolic syndrome. Biochemical parameters were measured by spectrophotometer.

RESULTS

The MM, LM, and LL genotype frequencies of the PON1 L55M polymorphism were 10.5, 43.4, and 46.1%, and 22.4, 46.6, and 31% and; the QQ, QR, and RR genotype frequencies of the PON1 Q192R polymorphism were 55.4, 38.6 and 6%; and 56.5, 34.8 and 8.7% in subjects with and without MetS, respectively. The L and M allele frequencies were 68 and 53%; and 32 and 47% for PON1 L55M in subjects with and without MetS, respectively. The Q and R allele frequencies for PON1 Q192R were 74 and 26% in both groups. There were significant differences in HDL-cholesterol level and PON1 activity in the genotypes QQ, QR, and RR of the PON1 Q192R polymorphism in subjects with MetS.

CONCLUSIONS

The PON1 Q192R genotypes had only effected on PON1 activity and HDL-cholesterol level in subjects with MetS. Different genotypes of the PON1 Q192R seem to be important candidates to make the subjects susceptible to MetS in the Fars ethnic group.

Alteration of Blood Oxidative Stress Status in Patients with Thoracic Aortic Dissection: A Pilot Study

BACKGROUND

Thoracic aortic dissection (TAD) is a life-threatening condition which usually occurs on an aneurysmal aortic wall. Although increasing data have shown that inflammation and oxidative stress play an important role in the patho-physiology of dissection, systemic oxidative stress status (OSS) has not been clearly determined in patients suffering from TAD.

METHODS

A cohort of 115 patients presenting type A or B TAD were admitted to our center from 2013 to 2017. Out of this cohort, 46 patients were included in a study on dissected aorta (LIege study on DIssected Aorta: LIDIA). In 18 out of the 46 patients, systemic OSS parameters were evaluated after TAD diagnosis by determination of eight different antioxidants, four trace elements, two markers of oxidative lipid damage and two inflammatory markers.

RESULTS

The 18 TAD patients included 10 men and 8 women (median age: 62 years; interquartile range: 55-68) diagnosed with type A (N = 8) or B (N = 10) TAD. Low plasma levels of vitamin C, β-carotene, γ-tocopherol, thiol proteins, paraoxonase and selenium were observed in these 18 patients. By contrast, the concentration of copper and total hydroperoxides, copper/zinc ratio, as well as inflammatory markers, were higher than the reference intervals. No difference was observed in oxidative stress biomarker concentrations between type A and B TAD patients.

CONCLUSIONS

This pilot study, limited to 18 TAD patients, revealed a heightened systemic OSS, determined at 15.5 days (median) after the initial diagnosis, in those TAD patients without complications (malperfusion syndrome and aneurysm formation). Larger studies on biological fluids are needed to better characterize the oxidative stress and interpret its consequence in TAD disease.

Gender Differences and Cardiometabolic Risk: The Importance of the Risk Factors

Metabolic syndrome (Mets) is a clinical condition characterized by a cluster of major risk factors for cardiovascular disease (CVD) and type 2 diabetes: proatherogenic dyslipidemia, elevated blood pressure, dysglycemia, and abdominal obesity. Each risk factor has an independent effect, but, when aggregated, they become synergistic, doubling the risk of developing cardiovascular diseases and causing a 1.5-fold increase in all-cause mortality. We will highlight gender differences in the epidemiology, etiology, pathophysiology, and clinical expression of the aforementioned Mets components. Moreover, we will discuss gender differences in new biochemical markers of metabolic syndrome and cardiovascular risk.

Arylesterase activity of paraoxonase 1 in patients with primary hypertension

Introduction

Paraoxonase 1 is an enzyme associated with high-density lipoprotein fraction and is considered to present antioxidant activity.

Objectives

The aim of the study was to assess the arylesterase activity of paraoxonase 1 (PON1) in the serum of patients with hypertension, due to effect of therapy and before treatment. Patients and Methods. The study was conducted in 76 patients with primary hypertension and 28 volunteers for the control group. Hypertensive subjects were assigned to one of three groups: well controlled (n=25), poorly controlled (n=26), and newly diagnosed before therapy (n=25) hypertension. We evaluated metabolic parameters in all participants using routine laboratory methods, as well as arylesterase activity of PON1.

Results

The four study groups differed with arylesterase activity of PON1 and the highest levels were found in patients with well controlled hypertension and the lowest in newly diagnosed. All patients diagnosed with hypertension presented negative correlations between PON1 and systolic and diastolic blood pressure.

Conclusions

Effective treatment of hypertension could result in increased PON1 activity, despite unfavorable homocysteine concentrations in blood. Untreated hypertension might decrease activity of PON.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Factors associated to serum paraoxonase 1 activity in patients with cardiovascular disease

OBJECTIVE

Paraoxonase 1 (PON1) is an enzyme that has antioxidant potential, which confers a protective effect against the atherosclerotic process. However, studies associating genetics, dietary patterns and PON1 activity in individuals with cardiovascular disease (CVD) are scarce. Thus, the aim of the current study was to evaluate the influence of dietary factors on serum PON1 in CVD patients.

METHODS

Cross-sectional, sub-study of the BALANCE Program Trial. All patients aged 45 years or older and had evidence of established atherosclerotic disease in the preceding 10 years. Body weight, height, waist circumference, blood pressure, lipid profile and fasting glucose were collected. Food intake was assessed with 24-h dietary recall. Data was analyzed using SAS University Edition and a P value ≤ 0.05 was considered statistically significant. Sample was divided into three groups, according to the PON1 T(-107)C genotype (CC, CT and TT) and serum PON1 activity (Low, Medium, High).

RESULTS

There were no genotype differences for major factors. However, the systolic blood pressure was lower for CT individuals (p<0.05). Intake of cholesterol, saturated fatty acids (SFA) and monounsaturated fatty acids (MUFAS) was higher in patients with lower PON1 activity. Lipid ingestion tended to be higher in patients with lower PON1 activity (p=0.08). In the multivariate logistic regression model, SFA intake (P=0.03), genotype (P=0.09), gender (P=0.04), age (P=0.07) and carbohydrate intake (P=0.16) contributed the most to the serum PON1 activity.

CONCLUSION

Based on these findings, nutritional guidance for these patients becomes essential, since dietary components interact with serum PON1 activity more than genotype.

Paraoxonase 2 protects against oxygen-glucose deprivation/reoxygenation-induced neuronal injury by enhancing Nrf2 activation via GSK-3β modulation

Paraoxonase 2 (PON2) is a powerful antioxidant that mediates cell survival under oxidative stress; however, its protection neurons against cerebral ischemia-reperfusion injury-induced oxidative stress remains unclear. This study aimed to determine the precise regulating role of PON2 in neuronal survival under oxidative stress. An in vitro model of cerebral ischemia-reperfusion injury was used to assess the effect of PON2 on oxidative stress induced by oxygen-glucose deprivation/reoxygenation (OGD/R). Results showed that PON2 expression in neurons was decreased due to OGD/R exposure. A series of functional experiments revealed that upregulated PON2 improved OGD/R-impaired viability and attenuated OGD/R-induced increases in apoptosis and reactive oxygen species in neurons. Decreased PON2 expression enhanced neuronal sensitivity to OGD/R-induced injury. Overexpressed PON2 markedly enhanced the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) in the nucleus and increased the levels of Nrf2-mediated transcriptional activity. Furthermore, PON2 enhanced the Nrf2 activation by modulating glycogen synthase kinase-3β (GSK-3β). Inhibition of GSK-3β substantially abrogated the PON2 knockdown-mediated suppression of Nrf2 activity. Notably, Nrf2 inhibition partially reversed the neuroprotective effects of PON2 overexpression in OGD/R-exposed neurons. These findings indicate that PON2 alleviates OGD/R-induced apoptosis and oxidative stress in neurons by potentiating Nrf2 activation via GSK-3β modulation. This study highlights the potential neuroprotective function of PON2 against cerebral ischemia-reperfusion injury.

Role of Paraoxonase1 in the Regulation of High-Density Lipoprotein Functionality and in Cardiovascular Protection

Significance: Human paraoxonase (PON) is a member of the gene family that includes paraoxonase 1 (PON1), PON2, and PON3. PON is known for its capacity to hydrolyze a wide range of substrates, including organophosphorus compounds, nerve gases, and aromatic carboxylic acid esters. Recent Advances: Several studies have highlighted the involvement of PON, particularly PON1, in the modulation of the capacity of high-density lipoprotein (HDL) to protect against the atherosclerosis process and its clinical manifestations. PON1 exhibits antioxidant and anti-inflammatory activities and may be involved in the regulation of the principal antiatherogenic activity of HDL, that is, the regulation of the reverse cholesterol transport process. Critical Issues: Although epidemiological studies have shown that there is an inverse relationship between HDL levels and cardiovascular risk, several studies have emphasized the importance of HDL functionality in protecting against cardiovascular diseases (CVD). Given that PON1 is involved in several atheroprotective functions of HDL, the aim of this article is to review the existing literature on PON1 and to discuss the principal mechanisms by which PON1 may exert its different activities. Future Directions: The elucidation of the mechanisms by which PON1 modulates the functionality of HDL as well as the identification of the interventions that stimulate PON1 activity and/or increase its plasma concentration would make it possible to propose new strategies to prevent CVD. Antioxid. Redox Signal. 34, 191-200.

The Role of PON1 Variants in Disease Susceptibility in a Turkish Population

Paraoxonase 1 (PON1) enzyme plays a major role in antioxidant defense and protects the cells against reactive species. The most common PON1 Q192R and L55M polymorphisms are responsible for a wide variation of PON1 activity, which showed an up to 13-fold interindividual variation among the same genotype. PON1 genotypes were evaluated with the development of pancreatitis, colorectal cancer, and hypothyroidism in a hospital-based, case-control study. Individuals with rs662 G allele had a two-fold risk of developing hypothyroidism. A weak association was found between rs854560 T allele and pancreatitis. The results were preliminary. Further studies with a larger number and detailed biochemical parameters are needed.

Genetic associations and serum paraoxonase levels with atherosclerosis in western Iranian patients

The oxidative modification of low-density lipoprotein (LDL) in the arterial wall plays a pivotal role in the initiation and progression of atherosclerosis which is a complex and progressive disorder. Paraoxonase1 (PON1), which is required for lipid metabolism, is believed to protect LDL from oxidation. The relationship between PON1 gene Leusin55Methionin (L55M) and Glutamine192Arginine (Q192R) polymorphisms in western Iranians with atherosclerosis and its association with enzyme activity and oxidized low-density lipoprotein (oxLDL) were examined in the present study. In this study, blood specimens were collected from 145 healthy individuals and 154 patients with atherosclerosis proven by angiography referred to Shahid Madani Hospital, Khorramabad, Iran. Genomic deoxy ribonucleic acid (DNA) was extracted from whole blood. For all the subjects, restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) was carried out for the detection of L55M and Q192R polymorphisms. PON1 enzyme activity and the level of oxLDL were also evaluated. There was a 3.114-fold increase in the risk of developing atherosclerosis in the subjects presenting the PON1L55M, MM genotype compared to those with the LL genotype (OR 3.114; 95% CI 1.412-6.870). PON1Q192R polymorphism in the PON1 gene was not associated with atherosclerosis. Patients with atherosclerosis had significantly higher oxLDL and reduced PON1 enzyme activity (P < 0.05) compared to the controls. There was no association between the type of genotype, enzyme activity, and oxLDL level. It has been concluded that PON1L55M polymorphism and MM genotype are associated with an increased risk of coronary artery disease (CAD) in Iranian patients with atherosclerosis. We did not find any relationship between PON1Q192R polymorphism and atherosclerosis.

Linc-OIP5 working as a ceRNA of miR-616 promotes PON1 expression in HUEVC cells

Coronary atherosclerosis affects human health all over the world. PON1 was found to be associated with coronary atherosclerosis but the specific mechanism is still unclear. Non-coding RNA plays an important role in many diseases. In recent years, studies have focused on non-coding RNA in coronary atherosclerosis. In this study, we investigated the effect of non-coding RNA Linc-OIP5 on PON1 expression. Results showed that in the serum of patients with coronary atherosclerosis, there was lower PON1 activity and PON1 level, the same trend in Linc-OIP5, and the opposite trend in miR-616 expression. Through further cell experiments, with up-regulation or down-regulation of Linc-OIP5 and miR-616, we found that Linc-OIP5 positively regulated the expression of PON1 gene and its protein level, while miR-616 negatively regulated the expression of PON1 gene and protein. Through further functional experiments, we also found that the levels of superoxide dismutase (SOD) and nitric oxide (NO) related to oxidative stress also had corresponding changes. Further dual luciferase reporter assay demonstrated that Linc-OIP5 regulated PON1 expression as a ceRNA of miR-616. Thus Linc-OIP5 working as a ceRNA of miR-616 apparently promotes PON1 expression in HUEVC cells and Linc-OIP5 and miR-616 may be an ideal target for the treatment of coronary atherosclerosis in the future.

Association of Race and Major Adverse Cardiac Events (MACE): The Atherosclerosis Risk in Communities (ARIC) Cohort

Background and Aims

To evaluate the association of self-reported race with major adverse cardiac events (MACE) and modification of this association by paraoxonase gene (PON1, PON2, and PON3) single nucleotide polymorphisms (SNPs).

Methods

Included in this longitudinal study were 12,770 black or white participants from the Atherosclerosis Risk in Communities (ARIC) cohort who completed a baseline visit (1987–1989) with PON genotyping. Demographic, behavioral, and health information was obtained at baseline. MACE was defined as first occurrence of myocardial infarction, stroke, or CHD-related death through 2004. Cox proportional hazards regression was used to evaluate the association between race and MACE after adjustment for age, gender, and other demographic and cardiovascular risk factors such as diabetes and hypertension. Modification of the association between PON SNPs and MACE was also assessed.

Results

Blacks comprised 24.6% of the ARIC cohort; overall, 14.0% of participants developed MACE. Compared with whites, blacks had 1.24 times greater hazard of MACE (OR = 1.24,95%CI = 1.10,1.39) than whites after adjusting for age, gender, BMI, cigarette and alcohol use, educational and marital status, and aspirin use. This association became nonsignificant after further adjustment for high cholesterol, diabetes, and hypertension. None of the evaluated SNPs met the significance level (p < 0.001) after Bonferroni correction for multiple comparisons.

Conclusions

No association between race and MACE was identified after adjusting for high cholesterol, diabetes, and hypertension, suggesting that comorbidities are major determinants of MACE; medical intervention with focus on lifestyle and health management could ameliorate the development of MACE. Further studies are needed to confirm this observation.

Mutual Influences between Nitric Oxide and Paraoxonase 1

One of the best consolidated paradigms in vascular pharmacology is that an uncontrolled excess of oxidizing chemical species causes tissue damage and loss of function in the endothelial and subendothelial layers. The fact that high-density lipoproteins play an important role in preventing such an imbalance is integrated into that concept, for which the expression and activity of paraoxonases is certainly crucial. The term paraoxonase (aryldialkyl phosphatase, EC 3.1.8.1) encompasses at least three distinct isoforms, with a wide variation in substrate affinity, cell and fluid localization, and biased expression of polymorphism. The purpose of this review is to determine the interactions that paraoxonase 1 has with nitric oxide synthase, its reaction product, nitric oxide (nitrogen monoxide, NO), and its derived reactive species generated in an oxidative medium, with a special focus on its pathological implications.

Association of SOD2 A16V and PON2 S311C polymorphisms with polycystic ovary syndrome in Chinese women

PURPOSE

To investigate the relationship between superoxide dismutase 2 (SOD2) A16V and paraoxonase 2 (PON2) S311C gene variants and the risk of polycystic ovary syndrome (PCOS) and evaluate the effects of the genotypes on clinical, hormonal, metabolic and oxidative stress indexes in Chinese women.

METHODS

This is a cross-sectional study of 932 patients with PCOS and 745 control women. For the clinical and metabolic association study of genotypes, 631 patients and 492 controls were included after excluding the subjects with interferential factors. Genotypes were determined by polymerase chain reaction (PCR) and restriction fragment length polymorphism analysis. Serum total oxidant status, total antioxidant capacity (T-AOC), oxidative stress index and malondialdehyde (MDA) levels, and clinical and metabolic parameters were also analyzed.

RESULTS

The prevalence of the A allele of SOD2 A16V polymorphism was significantly greater in patients with PCOS than in control subjects. Genotype (AA + AV) remained a significant predictor for PCOS in prognostic models including age, body mass index, insulin resistance index, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglycerides (TGs) as covariates. Patients carrying the A allele had significantly higher serum luteinizing hormone (LH) levels, and the ratio of LH to follicle-stimulating hormone compared with patients with the VV genotype. We also showed that patients carrying the C allele of the PON2 S311C polymorphism had lower T-AOC compared with patients carrying the SS genotype. However, no significant differences were observed in the frequencies of the S311C genotypes and alleles of the PON2 gene between PCOS and control groups.

CONCLUSION

The SOD2 A16V, but not PON2 S311C, polymorphism may be one of the genetic determinants for PCOS in Chinese women.

Paraoxonase 1, HDL Subclasses and Post Surgery Acute Inflammation: A Pilot Study

High density lipoproteins (HDL) structure and function studies are needed to better understand the heterogeneous nature of the HDL particle, and its interaction with associated proteins such as apolipoprotein A-1 (ApoA-1), paraoxonase 1 (PON1) and the environment. Our study assesses the effects of acute inflammation on PON1 and HDL subclasses in post-surgical colorectal cancer patients. PON1 was measured kinetically through its arylesterase and lactonase activity and HDL sub-classes were measured using Quantimetrix Lipoprint^® System. White blood cells (WBC) counts, c-reactive protein (CRP) and serum amyloid A (SAA) levels were also analyzed using standard techniques. Our findings show that baseline PON1 activity is lower in colorectal cancer patients and significant reductions are observed in the acute inflammatory state post-surgery. PON1 changes are also inversely related to inflammatory markers such as SAA and CRP. In addition, our preliminary findings show that small and intermediate HDL decreases post-op Day 1. In conclusion, our study demonstrates the effects of chronic and acute inflammation on PON1. Specifically, PON1 arylesterase and lactonase activity is lower in states of chronic inflammation and further decreased in the acute inflammatory state. Additionally, in our limited sample size, while changes in PON1 and HDL subclasses may be variable in the acute inflammatory period, small HDL decreased with a loss of PON1 activity in the subacute phase.

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.

Serum paraoxonase 1 activity and protein N-homocysteinylation in primary human endometrial cancer

Paraoxonase 1 plays an important role in protection from oxidative stress and also decomposes homocysteine thiolactone, the toxic metabolite of homocysteine. A limited number of reports evaluated the role of paraoxonase 1 in women affected by female genital tract neoplasms, including endometrial cancer. This study aimed to analyze the paraoxonase activity in the group of endometrial cancer patients (n = 48) who underwent primary surgery and to compare the data available with a well-matched control group (n = 30). Due to the role of paraoxonase 1 in the metabolism of homocysteine (Hcy) thiolactone, the amount of Hcy-thiolactone as well as total serum Hcy concentrations was also measured. Serum paraoxonase 1 activity toward synthetic substrates, paraoxon and phenyl acetate, in the study group was significantly lower compared to the control one. The mean paraoxonase 1 activity toward homocysteine thiolactone tended to be lower in the endometrial cancer group but this difference was not significant. There was no relationship between endometrial cancer and Q192R polymorphism of PON1 assessed by the dual substrate method. No differences in paraoxonase 1 activity between endometrial cancer subgroups according to clinico-pathological features were detected. Total serum homocysteine and protein-bound homocysteine thiolactone did not differ between control and cancer groups. In conclusion, reduced paraoxonase 1 activity suggests diminished important antioxidant mechanisms during the development of primary endometrial cancers in humans. PON1 Q192R polymorphism is not associated with the risk of endometrial cancer. Despite lower paraoxonase 1 activity, homocysteine concentration, and protein N-homocysteinylation in endometrial cancers do not differ from matched controls.

Cardiovascular Benefits of Phenol-Enriched Virgin Olive Oils: New Insights from the Virgin Olive Oil and HDL Functionality (VOHF) Study

SCOPE

The main findings of the "Virgin Olive Oil and HDL Functionality" (VOHF) study and other related studies on the effect of phenol-enriched virgin olive oil (VOO) supplementation on cardiovascular disease are integrated in the present work.

METHODS AND RESULTS

VOHF assessed whether VOOs, enriched with their own phenolic compounds (FVOO) or with those from thyme (FVOOT), improve quantity and functionality of HDL. In this randomized, double-blind, crossover, and controlled trial, 33 hypercholesterolemic subjects received a control VOO (80 mg kg-1 ), FVOO (500 mg kg-1 ), and FVOOT (500 mg kg-1 ; 1:1) for 3 weeks. Both functional VOOs promoted cardioprotective changes, modulating HDL proteome, increasing fat-soluble antioxidants, improving HDL subclasses distribution, reducing the lipoprotein insulin resistance index, increasing endogenous antioxidant enzymes, protecting DNA from oxidation, ameliorating endothelial function, and increasing fecal microbial metabolic activity. Additional cardioprotective benefits were observed according to phenol source and content in the phenol-enriched VOOs. These insights support the beneficial effects of OO and PC from different sources.

CONCLUSION

Novel therapeutic strategies should increase HDL-cholesterol levels and enhance HDL functionality. The tailoring of phenol-enriched VOOs is an interesting and useful strategy for enhancing the functional quality of HDL, and thus, it can be used as a complementary tool for the management of hypercholesterolemic individuals.

Association of Paraoxonase-1 Q192R (rs662) Single Nucleotide Variation with Cardiovascular Risk in Coffee Harvesters of Central Colombia

Paraoxonase 1 (PON1), a high-density lipoprotein-associated antioxidant enzyme, hydrolyzes several organophosphate pesticides and oxidized lipids. The PON1 Q192R polymorphism affects the catalytic efficiency and is considered a risk factor for pesticide intoxication and cardiovascular disease (CVD) but the association is not consistent between individuals or populations. We aimed to study the association of PON1 Q192R polymorphism with CVD risk in coffee harvesters of central Colombia. Demographics were collected from 205 subjects via standardized questionnaires. Lipid profiles and serum butyrylcholinesterase (BChE) were measured by standard procedures. The calculated 10-year atherosclerotic CVD (ASCVD) risk was used as the cardiovascular risk estimate. Q192R genotype was determined by real-time PCR. Prevalence of hypertension, hypercholesterolemia, and the 10-year ASCVD risk was 33%, 62%, and 22%, respectively. BChE levels were no indicative of recent pesticide exposure, although a positive correlation was observed with BChE and hypercholesterolemia. The Q192R genotype frequencies were 38% (QQ), 44% (QR), and 18% (RR). We found an association of the 192Q genotype with hypertension. The results of this study signal the importance to evaluate the influence and potential interactions of BChE and PON1 192Q allele with known genetic and environmental factors implicated in the pathogenesis of CVD.

Chronic Kidney Disease and Disproportionally Increased Cardiovascular Damage: Does Oxidative Stress Explain the Burden?

Chronic kidney disease (CKD) patients are among the groups at the highest risk for cardiovascular disease and significantly shortened remaining lifespan. CKD enhances oxidative stress in the organism with ensuing cardiovascular damage. Oxidative stress in uremia is the consequence of higher reactive oxygen species (ROS) production, whereas attenuated clearance of pro-oxidant substances and impaired antioxidant defenses play a complementary role. The pathophysiological mechanism underlying the increased ROS production in CKD is at least partly mediated by upregulation of the intrarenal angiotensin system. Enhanced oxidative stress in the setting of the uremic milieu promotes enzymatic modification of circulating lipids and lipoproteins, protein carbamylation, endothelial dysfunction via disruption of nitric oxide (NO) pathways, and activation of inflammation, thus accelerating atherosclerosis. Left ventricular hypertrophy (LVH) and heart failure are hallmarks of CKD. NADPH oxidase activation, xanthine oxidase, mitochondrial dysfunction, and NO-ROS are the main oxidative pathways leading to LVH and the cardiorenal syndrome. Finally, a subset of antioxidant enzymes, the paraoxonases (PON), deserves special attention due to abundant clinical evidence accumulated regarding reduced serum PON1 activity in CKD as a contributor to the increased burden of cardiovascular disease. Future, meticulously designed studies are needed to assess the effects of antioxidant therapy on patients with CKD.

Dysfunctional high-density lipoproteins have distinct composition, diminished anti-inflammatory potential and discriminate acute coronary syndrome from stable coronary artery disease patients

There is a stringent need to find means for risk stratification of coronary artery diseases (CAD) patients. We aimed at identifying alterations of plasma high-density lipoproteins (HDL) components and their validation as dysfunctional HDL that could discriminate between acute coronary syndrome (ACS) and stable angina (SA) patients. HDL₂ and HDL₃ were isolated from CAD patients’ plasma and healthy subjects. ApolipoproteinAI (apoAI), apoAII, apoCIII, malondialdehyde (MDA), myeloperoxidase (MPO), ceruloplasmin and paraoxonase1 (PON1) were assessed. The anti-inflammatory potential of HDL subfractions was tested by evaluating the secreted inflammatory molecules of tumor necrosis factor α-activated endothelial cells (EC) upon co-incubation with HDL₂ or HDL_3. We found in ACS versus SA patients: 40% increased MPO, MDA, apoCIII in HDL₂ and HDL₃, 35% augmented apoAII in HDL₂, and in HDL₃ increased ceruloplasmin, decreased apoAII (40%) and PON1 protein and activity (15% and 25%). Co-incubation of activated EC with HDL₂ or HDL₃ from CAD patients induced significantly increased levels of secreted inflammatory molecules, 15–20% more for ACS versus SA. In conclusion, the assessed panel of markers correlates with the reduced anti-inflammatory potential of HDL subfractions isolated from ACS and SA patients (mostly for HDL₃ from ACS) and can discriminate between these two groups of CAD patients.

Phenol-enriched olive oils modify paraoxonase-related variables: A randomized, crossover, controlled trial

SCOPE

Low paraoxonase (PON)1 activities, and high PON1 and low PON3 protein levels are characteristic of cardiovascular disease. Our aim was to assess short- and long-term effects of virgin olive oils (VOO), enriched with their own phenolic compounds (PC; FVOO) or with them plus complementary PC from thyme (FVOOT), on PON-related variables and the mechanisms involved.

METHODS AND RESULTS

Two randomized, controlled, double-blind, and crossover interventions were conducted. In an acute intake study, participants ingested three FVOOs differing in PC content. In a sustained intake study, participants ingested a control VOO and two different FVOOs with the same PC content but differing in PC source. Acute and sustained intake of VOO and FVOO decreased PON1 protein and increased PON1-associated specific activities, while FVOOT yielded opposite results. PON3 protein levels increased only after sustained consumption of VOO. Mechanistic studies performed in rat livers showed that intake of isolated PC from VOO and from thyme modulate mitogen-activated protein kinases and peroxisome proliferator-activated receptors regulating PON synthesis, while a combination of these PCs cancels such regulation.

CONCLUSION

This study reveals that the intake of phenol-enriched FVOOs modulates oxidative balance by modifying PON-related variables according to PC content and source, and this modulation can be perceived as beneficial.

Paraoxonase activities in human follicular fluid: role in follicular maturation

The paraoxonases (PONs) are antioxidant enzymes associated with beneficial effects against several diseases and some exposures. Little is known, however, about the role of PONs in human reproduction. This work was conducted to investigate whether any association existed between the activities of the PON enzymes (1, 2, and 3) with the follicular size and fertility parameters in assisted reproduction. The study included 100 subfertile women (patients) and 55 proven fertile women (oocyte donors), all undergoing an ovarian stimulation cycle. Follicular fluid from small (diameter <12 mm) and large (diameter ≥18 mm) follicles was collected from each woman. The PONs were quantified in follicular fluid by immunoblotting. PON1 arylesterase and paraoxonase, PON2 methyl paraoxonase and PON3 simvastatinase activities from both donors and patients were significantly higher (P < 0.001) in follicular fluid from large follicles compared with small ones. In large follicles, PON3 activity was significantly higher (P < 0.01) in donors compared with patients. Follicular fluid PON1 arylesterase and paraoxonase activity was positively correlated with the number of retrieved oocytes in donors. This study shows an increase in the activities of PONs with follicle size, thus providing indirect evidence for the role of PONs in follicle maturation.

Paraoxonase and atherosclerosis-related cardiovascular diseases

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

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.

Systematic review and meta-analysis deciphering the impact of fibrates on paraoxonase-1 status

OBJECTIVE

A significant residual cardiovascular risk is consistently observed in patients treated with statins. A combined treatment with fibrates reduces cardiovascular events in very high-risk patients. Because this is apparently unconnected to an improvement in lipid-related outcomes we hypothesized that the cardioprotective effects of fibrates might be associated with an improvement in paraoxonase-1 (PON1) status.

METHOD

The search for existing evidence, using the Medline, Scopus and Cochrane databases, was systematic and followed the PRISMA statement without restrictions on publication date. We excluded non-clinical and observational studies and we extracted data on baseline and post-treatment values of serum PON1 activity and other measurements of PON1 status.

RESULTS

Nine studies (including 12 treatment arms) in patients with hyperlipidemia, diabetes or metabolic syndrome treated with fibrates, alone or in combination with statins, were included to synthesize results. A meta-analysis of the data using a random-effects model revealed a significant increase in serum PON1 activity following fibrate therapy (WMD: 15.64U/L, 95% CI: 6.94, 24.34, p<0.001), an effect that was robust and not sensitive to any particular study. Subgroup analysis indicated differences in the effect size among types of fibrates and that PON1 alterations were associated with high-density lipoprotein cholesterol changes following fibrate therapy.

CONCLUSIONS

Results indicate a significant PON1-enhancing effect of fibrates. Whether this effect is associated with a clinical benefit, although likely, remains to be further investigated.

Oxidative Stress Genes, Antioxidants and Coronary Artery Disease in Type 2 Diabetes Mellitus

The worldwide increasing prevalence of obesity and sedentary lifestyle is the main cause of the rising incidence of T2DM. Due to chronic macrovascular and microvascular complications, T2DM represent a huge socioeconomic burden in the world. Oxidative stress is a key pathogenic mechanism implicated in diabetic coronary artery disease (CAD). Polymorphisms of oxidative stress genes are known to influence oxidative stress levels and are therefore thought to impact CAD pathogenesis. Identifying higher risk groups would be rational, since it would allow better sample selection and thus better results in antioxidant trials. In this review, we summarize the evidence of oxidative stress gene polymorphisms related to the pathogenesis of CAD. Moreover, we provide a review of antioxidants tested in subjects with CAD.

A preliminary study of paraoxonase-1 in infected patients with an indwelling central venous catheter

OBJECTIVES

Identification of biochemical markers to diagnose bloodstream infections in patients with a central venous catheter (CVC) inserted is an active research pursuit. Paraoxonase-1 (PON1) is an enzyme participating in the innate immune system protecting against toxic substances and infectious agents. We investigated the relationships between serum PON1 alterations and the characteristics of infection in a group of patients with a CVC implant.

METHODS

Patients (n=114) who had had an inserted CVC removed because of infection or because the usefulness was at an end, and 407 healthy volunteers were recruited. In all participants we measured serum PON1 lactonase and paraoxonase activities, PON1 concentration and genetic polymorphisms, together with levels of the chemokine (C-C motif) ligand 2 (CCL2), procalcitonin and C-reactive protein (CRP).

RESULTS

Patients with an acute concomitant infection (ACI) had higher CCL2, CRP and procalcitonin concentrations than the control group, together with lower paraoxonase and lactonase activities and specific activities. The areas under the curve of the receiver operating characteristic plots for paraoxonase and lactonase specific activities in the discrimination between patients with or without and ACI were 0.81 (0.73-0.89) and 0.81 (0.71-0.89), respectively, indicating the high diagnostic accuracy of these parameters.

CONCLUSION

This preliminary study suggests that the measurement of PON1 may be useful as a tool for the diagnosis of ACI in patients with an indwelling CVC.

Correlation between genetic polymorphism of matrix metalloproteinase-9 in patients with coronary artery disease and cardiac remodeling

Objective:

To explore the correlation between genetic polymorphism of matrix metalloproteinase-9 (MMP-9) in patients with coronary artery disease (CAD) and cardiac remodeling.

Methods:

A total of 272 subjects who received coronary angiography in our hospital from July 2008 to September 2013 were selected, including 172 CAD patients (CAD group) and another 100 ones (control group). Both groups were subjected to MMP-9 and ultrasonic detections to determine vascular remodeling and atherosclerotic plaques. C1562G polymorphism of MMP-9 gene was detected, and correlation with vascular remodeling and atherosclerotic plaque was analyzed.

Results:

Serum MMP-9 level of CAD group (330.87±50.39 ng/ml) was significantly higher than that of control group (134.87±34.02 ng/ml) (P<0.05). Compared with control group, CAD group had significantly higher intima-media thickness, and significantly lower systolic peak velocity, mean systolic velocity and end-diastolic velocity (P<0.05). Total area of stenotic blood vessels was 67.34±22.98 mm², while that of control blood vessels was 64.00±20.83 mm². G/G, G/C and C/C genotype frequencies of MMP-9 differed significantly in the two groups (P<0.05). G and C allele frequencies of CAD group (70.9% and 29.1%) were significantly different from those of control group (50.0% and 50.0%) (P<0.05). G/G, G/C and C/C genotypes were manifested as lipid-rich, fibrous and calcified or ulcerated plaques respectively. Total area of stenotic blood vessels of G/G genotype significantly exceeded those of G/C and C/C genotypes (P<0.05), whereas the latter two had no significant differences.

Conclusion:

CAD promoted 1562C-G transformation of MMP-9 gene into genetic polymorphism, thus facilitating arterial remodeling and increasing unstable atherosclerotic plaques.

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.