Serum paraoxonase-1 (PON1) activities (PONase/AREase) and polymorphisms in patients with type 2 diabetes mellitus in a North-West Indian population

Paraoxonase gene polymorphisms: Understanding the biochemical and genetic basis of coronary artery disease

Objectives

Serum paraoxonase (PON) is a glycoprotein with antioxidant and anti-atherosclerotic activities. The Q192R and L55M gene polymorphisms of PON have been implicated as risk factors for coronary artery disease (CAD) but have not been extensively explored in South Indians. We aimed to assess the Q192R and L55M genetic polymorphisms of the PON1 gene in participants with CAD, including genotypes and allele frequencies for PON1 gene polymorphism.

Methods

This prospective case-control study involved 20 participants in each group. Patients with angiographically demonstrated CAD were included in the case group. PON1 activity was measured, and PON gene polymorphism was determined. Serum PON was quantitatively analyzed with a RayBio® Human PON1 ELISA kit. Chi square tests were used to assess the association of the genotypes with sex and any comorbidities in cases and controls. A p value ≤ 0.05 was considered significant.

Results

Mutant type L55M polymorphism was observed in 50% of patients, whereas wild type Q192R polymorphism was observed in 42.5% of the participants. The mean PON values between groups did not significantly differ, whereas PON U/L was significantly (p = 0.001) lower in the case group. The L55M polymorphism did not significantly differ between the case and the control groups (p = 0.213), whereas the Q192R polymorphism was statistically significant in cases compared with controls (p ≤ 0.001).

Conclusion

Low plasma PON1 and HDL levels, and higher LDL, total cholesterol and triglyceride levels were observed in patients with CAD. More patients with CAD than healthy individuals had Q192R polymorphism.

The Relevance of Noncoding DNA Variations of Paraoxonase Gene Cluster in Atherosclerosis-Related Diseases

The human paraoxonase (PON) gene cluster is comprised of three contiguous genes (PON1, PON2 and PON3) of presumably common origin coding three lactonases of highly similar structure and substrate specificity. The catalytic activity of PON proteins is directed toward artificial organophosphates and in physiological conditions toward thiolactones and oxidized phospholipids. Consequently, PON enzymes are regarded as an effective defense against oxidative stress and, as a result, against atherosclerosis development. Additionally, both PON's serum activity and its concentration are influenced by several polymorphic variations in coding and noncoding DNA regions of the PON gene cluster remaining in linkage disequilibrium. Hence, the genetic polymorphism of the PON gene cluster may contribute to atherosclerotic process progression or deceleration. In this review the authors analyzed the relevance of noncoding DNA polymorphic variations of PON genes in atherosclerosis-related diseases involving coronary and peripheral artery disease, stroke, diabetes mellitus, dementia and renal disease and concluded that the effect of PON gene cluster' polymorphism has a considerable impact on the course and outcome in these conditions. The following PON genetic variations may serve as additional predictors of the risk of atherosclerosis in selected populations and individuals.

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

INTRODUCTION/OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Evaluation of Relationship Between Arylesterase-Based Activity and Genetic Variants of Paraoxonase1 in T2DM Patients within Golestan Province

Arylesterase activity of Paraoxonase-1 (PON1) enzyme may be play important role in initiation and progression of several diseases. Activity or serum level of Arylesterase can be affected by many genetic alterations such as SNPs. The reduction in the activity and serum level of Arylesterase could be involved in Type2 diabetes mellitus (T2DM). The aim of this investigation is to examine the association between Arylesterase activity and promoter polymorphism (- 108C > T) of PON1gene in patients with T2DM in Golestan Province, northern area of Iran. Achievement of this purpose was due to DNA obtaining from blood then SNP determination using PCR-RFLP and Arylesterase activity measurement in the serum of 90 normal individuals and 90patients suffering diabetes. Data was processed by SPSS software version 16. The significant association was observed between the Arylesterase activity and three genotypes of PON1 gene such as CC, CT, and TT in subjects with T2DM. In the present study, it has been shown level of Arylestrase activity of PON1 in patients (117.33 ± 63.96) is lower than it in control group (289.33 ± 68.38); P < 0.05. Our results declared that activity of Arylesterase in diabetic patients was significantly lower than the healthy individuals.

Plasma paraoxonase1 activity in rats treated with monocrotophos: a study of the effect of duration of exposure

We have earlier demonstrated the potential of monocrotophos (MCP), a highly toxic organophosphorus insecticide (OPI), to elicit insulin resistance in rats after chronic exposure. Given the understanding of role of paraoxonase1 (PON1) in OPI toxicity and diabetes pathology, this study was envisaged to understand the effect of duration of exposure to MCP on plasma PON1 activity in rats. Rats were administered MCP per os at 1/20 and 1/10^th LD₅₀ as daily doses for 180 days. Interim blood samples were collected at 15, 30, 45, 90 and 180 d for analysis of plasma parameters. Exposure to MCP for 45 resulted in persistent trend of hyperinsulinemia, while significant increase in fasting glucose levels was observed after 180 days. MCP caused suppression of plasma cholinesterase activity though the study period, albeit extent of inhibition was more severe during the early phase of the study. Exposure to MCP for 180 d resulted in hypertriglyceridemia and marginal decrease in HDL-C levels. MCP failed to modulate PON1 activity in plasma during the early phase of the study (up to 45 d). However, prolonged exposure resulted in significant increase in the plasma PON1 activity. This suggests that manifestation of insulin resistance in rats subjected to chronic exposure to MCP is associated with increase in PON1 activity. Our work provides rationale for studying whether the increase in PON1 activity observed in the present study serves to counter the deleterious effect of long term exposure to organophosphorus insecticides on metabolic homeostasis.

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

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

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

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

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

Association of Serum Paraoxonase 1 Activities, Polymorphisms and Oxidative Stress in Breast Cancer Patients with Type 2 Diabetes Mellitus

Background

The aim of the study was to investigate the association of paraoxonase 1 (PON1) polymorphism, PON1/arylesterase (ARE) activity and oxidative stress index (OSI) in breast cancer (BC) patients with type 2 diabetes (DM).

Methods

Our study group consisted of 30 healthy women (HV group) and 66 female BC patients. The BC patients were divided into two groups: those with (n=37) and without DM (n=29) (BDM and NBDM group). Genotyping of PON1 Q192R and L55M polymorphisms were done by polymerase chain reaction (PCR) - restriction fragment length polymorphism (RFLP) method. Serum PON1/ARE enzyme activities, total oxidant status (TOS) and total antioxidant status (TAS) were analysed by spectrophotometric method. The ratio of TOS to TAS was accepted as the oxidative stress index (OSI).

Results

PON1 Q192R genotype frequency distribution was significantly different in the BDM group compared to the NBDM group (p=0.021). When alleles distribution was examined, R and L alleles were significantly lower, Q and M alleles were significantly higher in the BDM group than in the NBDM group (p<0.001). TOS and OSI were statistically higher in BC patients than HV group (p<0.001).

Conclusions

Our results suggest that PON1 gene Q and M alleles may be the risk factors predisposing formation of BC due to increased oxidant damage seen in DM. However, these statements require further confirmation with screening PON1 polymorphism in a greater number of patients with DM, and also wide range follow-up studies are necessary for the same purpose.

Association of PON1 gene promoter DNA methylation with the risk of Clopidogrel resistance in patients with coronary artery disease

BACKGROUND AND AIMS

The failure of therapeutic response to clopidogrel in platelet inhibition, which is called clopidogrel resistance (CR), is more likely to cause cardiovascular events. We aimed to study the contribution of promoter DNA methylation of paraoxonase 1 (PON1) to the risk of clopidogrel poor response.

METHODS

Through VerifyNow P2Y12 assay, patient' platelet functions were measured. Among 57 non-CR and 49 CR patients, the levels of DNA methylation in four CpG dinucleotides on the PON1 promoter were tested using bisulfite pyrosequencing technology. Besides, the relative expression of PON1 mRNA was analyzed by quantitative real-time PCR. Logistic regression was applied to investigate the interaction of PON1 methylation and clinical factors in CR.

RESULTS

In the subgroup with dyslipidemia, we discovered that higher CpG4 levels of the PON1 promoter indicated a poorer clopidogrel response (cases versus controls (%): 51.500 ± 14.742 vs 43.308 ± 10.891, P = 0.036), and the PON1 mRNA expression was reduced in CR patients. Additionally, the logistic regression indicated that higher level of albumin and the index of ALT were related to a lower risk of CR, and the index of AST as well as the quantity of stent may be positively associated with CR.

CONCLUSIONS

The DNA methylation of CpG4 in the PON1 promoter would lead to a low expression of PON1 mRNA, which might induce clopidogrel resistance in the patients with dyslipidemia, and the number of stents might be a risk for CR.

Paraoxonase 1 activities and its gene promoter single nucleotide polymorphisms (-108, -126, and -162) in diabetes mellitus

Background

Paraoxonase 1 (PON1) enzyme is known enzyme with, aryl esterase, phosphatase, peroxidase, and lactonase activities. According to some studies, the activity of PON1 enzyme is decreased in type 2 diabetic patients. We analyzed the enzyme activity and its single nucleotide polymorphisms (SNPs) distribution on promoter regions (-108, -126, and -162) in type 2 diabetic patients compared with non-diabetic individuals to reveal the likely relationship between PON1 activity and its gene promoter polymorphisms.

Methods

On the whole, 98 diabetic and 104 non-diabetic individuals were examined in this study. The enzyme activity and the genotypes were studied using spectrophotometry, real-time PCR-HRM, and sequencing techniques, respectively.

Results

There was no meaningful difference in enzyme activity between two under-studied groups (P.V = 0.671). Moreover, no meaningful difference was also seen between two groups in terms of the frequency of polymorphism -108 (P.V = 0.277). The frequencies of SNPs -126 and -162, however, showed a meaningful difference between two groups (P.V = 0.000 and P.V = 0.017, respectively).

Conclusions

We indicated PON1 activity could be similar in DM-2 patients and non-DM-2 individuals. The significant role of SNP -108 in PON1 activity in DM-2 patients compared with non-DM-2 individuals was confirmed in the study too. On the other hand, the role of -162 and -126 SNPs in causing diabetes cannot be easily overlook because of a meaningful difference of their distribution in understudied groups. However, they may be attributed to DM-2-associated genes.

Punicalagin Decreases Serum Glucose Levels and Increases PON1 Activity and HDL Anti-Inflammatory Values in Balb/c Mice Fed a High-Fat Diet

Polyphenols are consumed daily in the human diet and are associated with reduced risk of a number of chronic diseases, including cancer, cardiovascular disease, and diabetes. Traditionally, the health benefits of polyphenols have been attributed to their antioxidant activity, but many studies might be hampered by oral administration and insignificant bioavailability. Rather than exerting a direct antioxidant effect, the mechanisms by which polyphenols express their beneficial effect seem to involve their interaction with proteins. The present study is aimed at broadening and confirming our recently published in vitro results showing that polyphenols may reduce atherosclerosis risk via interaction with proteins and lipoproteins related to atherosclerosis. The biological functions of punicalagin and quercetin in relation to glucose and lipid levels, paraoxonase 1 (PON1) activity, and inflammation were examined in vivo. Mice were fed a high-fat diet (HFD) for 12 weeks, and during the last 4 weeks, they received subcutaneous treatments via implanted minipumps, which released physiological concentrations of punicalagin, quercetin, or atorvastatin (as a positive control) daily into the serum. The HFD reduced serum PON1 activity, whereas punicalagin administration restored PON1 activity to the level of mice fed a normal diet. In addition, punicalagin significantly reduced glucose levels in HFD mice and improved HDL anti-inflammatory properties. In conclusion, beyond antioxidant activity, the mechanisms by which polyphenols exert their beneficial properties appear to involve their interaction with serum proteins that mediate HDL function and lipid-glucose state in the circulation.

The association between paraoxonase 1 activity and the susceptibilities of diabetes mellitus, diabetic macroangiopathy and diabetic microangiopathy

We carried out this meta‐analysis to explore the influence of paraoxonase 1 activity on the susceptibility of diabetes mellitus (DM), diabetic macroangiopathy and diabetic microangiopathy. Relevant studies were identified from PubMed, Web of Science and CNKI without language limitation, following the inclusion and exclusion criteria. Statistical analyses were implemented with the STATA 12.0 statistical software. Thirty‐six case‐control studies were included in the meta‐analyses, in which 35 for the association between paraoxonase 1 activity and DM risk, 8 for diabetic macroangiopathy and 7 for diabetic microangiopathy. Paraoxonase 1 activity was significantly associated with the susceptibility of DM in pooled population (SMD = −1.37, 95% CI = −1.79 ∼ −0.96, P = .000), and Asians (SMD = −2.00, 95% CI = −2.56 ∼ −1.44, P = .000), but not in non‐Asians (SMD = −0.44, 95% CI = −0.91 ∼ 0.03, P = .069). However, marked heterogeneity was existed (I² = 98.10%, P = .000) and subgroup analyses failed to investigate the sources of heterogeneity. Then, meta‐regression was performed and found that ethnicity could explain the observed between‐study heterogeneity (P = .002). Meanwhile, significant associations were found between paraoxonase 1 activity and diabetic macroangiopathy (SMD = −1.06, 95% CI = −1.63 ∼ −0.48, P = .000) and diabetic microangiopathy (SMD = −0.72, 95% CI = −1.32 ∼ −0.13, P = .018). In conclusion, paraoxonase 1 activity plays important roles in the risk of DM, diabetic macroangiopathy and microangiopathy with ethnicity differences. Further studies with large sample and well design are needed to confirm these results.

Paraoxonase (PON)-1: a brief overview on genetics, structure, polymorphisms and clinical relevance

Paraoxonase-1 (PON1) is a high-density lipoprotein-associated esterase and is speculated to play a role in several human diseases including diabetes mellitus and atherosclerosis. Low PON1 activity has been associated with increased risk of major cardiovascular events, therefore a variety of studies have been conducted to establish the cardioprotective properties and clinical relevance of PON1. The major aim of this review was to highlight the important studies and to subsequently assess if PON1 has clinical relevance. A review of the literature showed that there is currently insufficient data to suggest that PON1 has clinical relevance. It is our opinion that robust studies are required to clarify the clinical relevance of PON1.

Lyso-DGTS lipid isolated from microalgae enhances PON1 activities in vitro and in vivo, increases PON1 penetration into macrophages and decreases cellular lipid accumulation

High-density lipoprotein (HDL) plays an important role in preventing atherosclerosis. The antioxidant effect of HDL is mostly associated with paraoxonase 1 (PON1) activity. Increasing PON1 activity using nutrients might improve HDL function and quality and thus, decrease atherosclerotic risk. We previously isolated and identified a novel active compound, lyso-DGTS (C20:5,0) from Nannochloropsis sp. ethanol extract. In the present study, its effect on PON1 activities was examined and the mechanism by which the compound affects PON1 activity was explored. Lyso-DGTS elevated recombinant PON1 (rePON1) lactonase and esterase activities in a dose- and time-responsive manner, and further stabilized and preserved rePON1 lactonase activity. Incubation of lyso-DGTS with human serum for 4 h at 37 °C also increased PON1 lactonase activity in a dose-responsive manner. Using tryptophan-fluorescence-quenching assay, lyso-DGTS was found to interact with rePON1 spontaneously with negative free energy (ΔG = -22.87 kJ mol^-1 at 25 °C). Thermodynamic parameters and molecular modeling calculations showed that the main interaction of lyso-DGTS with the enzyme is through a hydrogen bond with supporting van der Waals interactions. Furthermore, lyso-DGTS significantly increased rePON1 influx into macrophages and prevented lipid accumulation in macrophages stimulated with oxidized low-density lipid dose-dependently. In vivo supplementation of lyso-DGTS to the circulation of mice fed a high-fat diet via osmotic mini-pumps implanted subcutaneously significantly increased serum PON1 lactonase activity and decreased serum glucose concentrations to the level of mice fed a normal diet. Our findings suggest a beneficial effect of lyso-DGTS on increasing PON1 activity and thus, improving HDL quality and atherosclerotic risk factors. © 2018 BioFactors, 44(3):299-310, 2018.

European versus Asian differences for the associations between paraoxonase-1 genetic polymorphisms and susceptibility to type 2 diabetes mellitus

Many studies have examined the associations between paraoxonase‐1 (PON1) genetic polymorphisms (Q192R, rs662 and L55M, rs854560) and the susceptibility to type 2 diabetes mellitus (T2DM) across different ethnic populations. However, the evidence for the associations remains inconclusive. In this study, we performed a meta‐analysis to clarify the association of the two PON1 variants with T2DM risk. We carried out a systematic search of PubMed, Embase, CNKI and Wanfang databases for studies published before June 2017. The pooled odds ratios (ORs) for the association and their corresponding 95% confidence intervals (CIs) were calculated by a random‐ or fixed‐effect model. A total of 50 eligible studies, including 34 and 16 studies were identified for the PON1 Q192R (rs662) and L55M (rs854560) polymorphism, respectively. As for the PON1 Q192R polymorphism, the 192R allele was a susceptible factor of T2DM in the South or East Asian population (OR > 1, P < 0.05) but represented a protective factor of T2DM in European population (OR = 0.66, 95% CI = 0.45–0.98) under a heterozygous genetic model. With regard to the PON1 L55M polymorphism, significant protective effects of the 55M allele on T2DM under the heterozygous (OR = 0.77, 95% CI = 0.61–0.97) and dominant (OR = 0.80, 95% CI = 0.65–0.99) genetic models were found in the European population, while no significant associations in the Asian populations under all genetic models (P > 0.05). In summary, by a comprehensive meta‐analysis, our results firmly indicated that distinct effects of PON1 genetic polymorphisms existed in the risk of T2DM across different ethnic backgrounds.

Association between promoter polymorphism (-108C>T) of paraoxonase1 gene and it's paraoxonase activity in patients with Type2 diabetes in northern Iran

Type 2 diabetes mellitus (T2DM) is one of the diseases which depend on the obesity associated with insulin resistance. Various factors, such as a reduction in the activity of paraoxonase-1 enzyme (PON1), could affect T2DM. PON1 is a multifunctional enzyme with paraoxonase and arylesterase activities. The Activity of PON1 is influenced by various SNPs. The aim of presence study is to investigate the association between promoter polymorphism (-108C>T) of PON1 gene and its paraoxonase activity in patients suffering from Type 2 diabetes in Golestan Province, north of Iran. To this end, genomic DNA was extracted from whole blood then genotyping was carried out using PCR-RFLP and enzymatic activity of paraoxonase was measured in the serum of 90 healthy subjects and 90 diabetic patients. Data was analyzed using SPSS version 16. The relationship between the level of paraoxonase activity with polymorphisms of CC, CT, and TT was statistically significant in patients with T2DM. There was a significant association between polymorphism C-108>T of PON1 and type2 diabetes mellitus, with 24.4% of control group subjects and 15.5% of patients having CC genotype; p<0.05. The ratio for CT genotype in target and control groups was 51.1% and 61.1% respectively; p<0.05. TT genotype was 33.3% in patients and 14.4% in the control group; p<0.05. In the present study, the highest frequency belonged to CT genotype in both the control and the target groups, followed by CC genotype in control group and TT genotype in target group. Our findings revealed that paraoxonase activity of PON1 in the control group was significantly higher in comparison with diabetic patients.

PON1 polymorphisms are associated with polycystic ovary syndrome susceptibility, related traits, and PON1 activity in Indian women with the syndrome

OBJECTIVE

To investigate the association of paraoxonase 1 (PON1) polymorphisms (L55M and Q192R) with polycystic ovary syndrome (PCOS) susceptibility and its related traits in Indian women.

DESIGN

Case-control study.

SETTING

Academic research institute, infertility, and endocrinology clinics.

PATIENT(S)

Controls (n = 326), women with PCOS (n = 482).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Genotypic and allelic frequency distribution, genotype-phenotype association, different PON1 activities (lactonase, arylesterase, and paraoxonase).

RESULT(S)

The genotypic and allelic frequency distributions of the L55M polymorphism were significantly different between lean controls and lean women with PCOS, and this polymorphism reduced the risk of PCOS development in lean but not in obese Indian women. Furthermore, this polymorphism was significantly associated with decreased 2-hour glucose, apolipoprotein B, free and bioavailable T, and free androgen index concurrent with increased sex hormone-binding globulin (SHBG) and FSH levels only in lean women with PCOS. However, Q192R polymorphism showed comparable genotypic frequency distribution between controls and women with PCOS. PON1 lactonase and arylesterase activities were significantly decreased in women with PCOS compared with controls. PON1 polymorphisms were shown to influence its activities.

CONCLUSION(S)

Our study showed that L55M, but not Q192R, polymorphism is significantly associated with reduced PCOS susceptibility only in lean women and also impacts glucose metabolism, lipid parameters, and hyperandrogenemia in them. Our study therefore suggests the possibility of differential genetic pathophysiology of PCOS between lean and obese women.

Significant interethnic differencies in functional variants of PON1 and P2RY12 genes in Roma and Hungarian population samples

Antiplatelet therapy with clopidogrel is one of the most common therapies given to patients worldwide. However, the clinical efficacy and toxicity of clopidogrel is not constant in every patient due to interindividual variations. There are several factors that contribute to these interindividual differencies such as SNPs in genes of specific receptors and enzymes. PON1 (paraoxonase 1) plays an important role in the bioactivation of clopidogrel. Single nucleotide polymorphisms of this gene decrease the activity of paraoxonase enzyme and lead to an unefficient clopidogrel effect. P2RY12 (purinergic receptor P2Y, G-protein coupled, 12) gene is coding a receptor, which is situated on the surface of the platelets and plays a role in ADP-induced platelet aggregation. In this study we investigated 2 functional SNPs of PON1 gene (rs662 and rs854560) and 3 variants of the P2RY12 gene (rs2046934, rs6798347, rs6801273) in samples pooled from average Hungarian Roma and Hungarian population samples with PCR-RFLP method. For the PON1 variants we detected that the R allele frequency was significantly lower in the Roma group compared to the Hungarian population. (0.249 vs 0.318 p < 0.001). By contrast, the frequency of the M allele was significantly higher in Roma than in Hungarians (0.332 vs 0.290 p < 0.05). For the 3 P2RY12 variants we could find significant differencies only in rs2046934: the frequency of the CC genotype is 7 times higher in Hungarians than in Romas (1.4 vs 0.2 %, p < 0.05). The data presented here represent a unique genetic profile in Roma people that has not been reported for other populations.

Persistent organic pollutants distribution in lipoprotein fractions in relation to cardiovascular disease and cancer

Persistent organic pollutants (POPs) are lipophilic environmental toxins that have been associated with cardiovascular disease (CVD) and cancer. The aim of this study was to investigate the concentrations of POPs in human high and low/very low-density lipoproteins (HDL and LDL/VLDL) and the possible association with CVD and cancer occurrence in individuals living in a contaminated area. Lipoproteins from 28 individuals (7 healthy controls, 8 subjects with cancer, 13 subjects with CVD) were isolated and the fraction-specific concentration of 20 different POPs was analyzed by high resolution gas chromatography/high resolution mass spectrometry. The activity of Paraoxonase 1 (PON1), an anti-oxidant in HDL, was determined in plasma of these 28 subjects and additional 50 subjects from the same area excluding diseases other than cancer or CVD. Fourteen polychlorinated biphenyls (PCBs) and three organochlorine pesticides were detected, and especially highly chlorinated PCBs were enriched in lipoproteins. Significantly higher concentrations of POPs were found among individuals with CVD or cancer compared to controls. Principal component analyses showed that POP concentrations in HDL were more associated with CVD, while POP concentrations in LDL/VLDL were more associated with cancer. PON1 activity was negatively correlated to sumPCB and a co-variation between decreased arylesterase-activity, increased PCB concentrations and CVD was found. This study shows that POPs are present in lipoproteins and were more abundant in individuals with CVD or cancer compared to healthy controls. The results also indicate that PCB exposure is accompanied by reduced PON1 activity that could impair the HDL function to protect against oxidation.

Antioxidant and anti-inflammatory role of paraoxonase 1: implication in arteriosclerosis diseases

Paraoxonase 1 (PON1) is a hydrolytic enzyme with wide range of substrates, and capability to protect against lipid oxidation. Despite of the large number of compounds that can be hydrolyzed by paraoxonase, the biologically relevant substrates are still not clearly determined. There is a massive in vitro and in vivo data to demonstrate the beneficial effects of PON1 in several atherosclerosis-related processes. The enzyme is primarily expressed in liver; however, it is also localized in other tissues. PON1 attracted significant interest as a protein that is responsible for the most of antioxidant properties of high-density lipoprotein (HDL). Several bioactive molecules such as dietary polyphenols, aspirin and its hydrolysis product salicylate, are known to stimulate PON1 transcription activation in mouse liver and HepG2 cell line. Studies on the activity, function, and genetic makeup have revealed a protective role of PON1. Some striking data were obtained in PON1 gene knockout and PON1 transgenic mouse models and in human studies. The goal of this review is to assess the current understanding of PON1 expression, enzymatic and antioxidant activity, and its atheroprotective effects. Results from in vivo and in vitro basic studies; and from human studies on the association of PON1 with coronary artery disease (CAD) and ischemic stroke will be discussed.

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

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

Paraoxonase 1 and homocysteine metabolism

Paraoxonase 1 (PON1), a component of high-density lipoprotein (HDL), is a calcium-dependent multifunctional enzyme that connects metabolisms of lipoproteins and homocysteine (Hcy). Both PON1 and Hcy have been implicated in human diseases, including atherosclerosis and neurodegeneration. The involvement of Hcy in disease could be mediated through its interactions with PON1. Due to its ability to reduce oxidative stress, PON1 contributes to atheroprotective functions of HDL in mice and humans. Although PON1 has the ability to hydrolyze a variety of substrates, only one of them-Hcy-thiolactone-is known to occur naturally. In humans and mice, Hcy-thiolactonase activity of PON1 protects against N-homocysteinylation, which is detrimental to protein structure and function. PON1 also protects against neurotoxicity associated with hyperhomocysteinemia in mouse models. The links between PON1 and Hcy in relation to pathological states such as coronary artery disease, stroke, diabetic mellitus, kidney failure and Alzheimer's disease that emerge from recent studies are the topics of this review.