Paraoxonase (PON1) and the risk for coronary heart disease and myocardial infarction in a general population of Dutch women

Paraoxonase 1 and atherosclerosis

Paraoxonase 1 (PON1), residing almost exclusively on HDL, was discovered because of its hydrolytic activity towards organophosphates. Subsequently, it was also found to hydrolyse a wide range of substrates, including lactones and lipid hydroperoxides. PON1 is critical for the capacity of HDL to protect LDL and outer cell membranes against harmful oxidative modification, but this activity depends on its location within the hydrophobic lipid domains of HDL. It does not prevent conjugated diene formation, but directs lipid peroxidation products derived from these to become harmless carboxylic acids rather than aldehydes which might adduct to apolipoprotein B. Serum PON1 is inversely related to the incidence of new atherosclerotic cardiovascular disease (ASCVD) events, particularly in diabetes and established ASCVD. Its serum activity is frequently discordant with that of HDL cholesterol. PON1 activity is diminished in dyslipidaemia, diabetes, and inflammatory disease. Polymorphisms, most notably Q192R, can affect activity towards some substrates, but not towards phenyl acetate. Gene ablation or over-expression of human PON1 in rodent models is associated with increased and decreased atherosclerosis susceptibility respectively. PON1 antioxidant activity is enhanced by apolipoprotein AI and lecithin:cholesterol acyl transferase and diminished by apolipoprotein AII, serum amyloid A, and myeloperoxidase. PON1 loses this activity when separated from its lipid environment. Information about its structure has been obtained from water soluble mutants created by directed evolution. Such recombinant PON1 may, however, lose the capacity to hydrolyse non-polar substrates. Whilst nutrition and pre-existing lipid modifying drugs can influence PON1 activity there is a cogent need for more specific PON1-raising medication to be developed.

The Relationship between Cancer and Paraoxonase 1

Extensive research has been carried out to understand and elucidate the mechanisms of paraoxonase 1 (PON1) in the development of diseases including cancer, cardiovascular diseases, neurological diseases, and inflammatory diseases. This review focuses on the relationship between PON1 and cancer. The data suggest that PON1, oxidative stress, chronic inflammation, and cancer are closely linked. Certainly, the gene expression of PON1 will remain challenging to study. Therefore, targeting PON1, redox-sensitive pathways, and transcription factors promise prevention and therapy in the development of several diseases, including cancer.

Paraoxonase-1 (PON-1) Arylesterase Activity Levels in Patients with Coronary Artery Disease: A Meta-Analysis

Aim

To review and compare the PON-1 arylesterase activity between coronary artery disease (CAD) and non-CAD patients.

Methods

Data were obtained by searching MEDLINE and Scopus for all investigations published between January 1, 2000 and March 1, 2021 comparing PON-1 arylesterase activity between CAD and controls.

Results

Twenty studies, based on 5417 patients, met the inclusion criteria and were included in the analysis. A random effect model revealed that PON-1 arylesterase activity was significantly lower in the CAD group compared to controls (SMD = -0.587, 95%CI = -0.776 to -0.339, p < 0.0001, I 2 = 92.3%). In CAD patients, the PON-1 arylesterase activity was significantly higher among CAD patients without diabetes mellitus (DM) compared to those with diabetes (SMD: 0.235, 95% CI: 0.014 to 0.456, p = 0.03, I 2 = 0%).

Conclusions

PON-1 activity is significantly lower in CAD patients, and those without DM presented a significantly higher PON-1 arylesterase activity.

Paraoxonase-1 Activity in Breast Cancer Patients Treated With Doxorubicin With or Without Trastuzumab

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PON-1 is an HDL-associated cardioprotective enzyme that prevents oxidized-LDL formation and has not previously been studied in cardio-oncology.

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To determine the associations between PON-1 and the development of CTRCD, the Pon and Aryl serum enzymatic activity levels of PON-1 were quantified in a cohort of 225 patients with breast cancer receiving doxorubicin with or without trastuzumab.

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After doxorubicin completion, the activity levels of both Pon and Aryl were significantly decreased.

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Early increases in the Pon enzymatic activity of PON-1 were associated with increased risk of CTRCD.

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With further study, PON-1 activity may provide insight into mechanistic risk prediction of CTRCD with doxorubicin chemotherapy.

The objective of this study was to determine associations of paraoxonase-1 (PON-1) with development of cancer therapy–related cardiac dysfunction (CTRCD). PON-1 is a cardioprotective enzyme associated with high-density lipoprotein that prevents oxidized low-density lipoprotein formation. Given the role of oxidative stress in doxorubicin-induced cardiotoxicity, PON-1 activity may have relevance for the prediction of CTRCD. In 225 patients with breast cancer receiving doxorubicin with or without trastuzumab, we quantified PON-1 activity through its paraoxonase (Pon) and arylesterase (Aryl) enzymatic activity at baseline, during, and after doxorubicin completion. Echocardiograms were performed at baseline, during therapy, and annually. CTRCD was defined as a decrease in left ventricular ejection fraction by ≥10% from baseline to <50%. Associations between baseline biomarkers and clinical variables were determined using multivariable linear regression. Associations between changes in biomarker activity and time to CTRCD were evaluated using Cox regression. Pon was directly associated with Black race and inversely associated with Stage 2 cancer. Aryl was inversely associated with body mass index. After doxorubicin completion, activity levels of Pon and Aryl were significantly decreased (median ratio compared with baseline for Pon: 0.95 [Q1-Q3: 0.81-1.07, P < 0.001]; for Aryl: 0.97 [Q1-Q3: 0.85-1.08, P = 0.010]). A total of 184 patients had an available quantitated echocardiogram at baseline and at least 1 follow-up visit. Increases from baseline in Pon at doxorubicin completion were independently associated with increased CTRCD risk (per 10% increase: hazard ratio [HR]: 1.21; 95% confidence interval [CI]: 1.05-1.39; P = 0.007). Associations between increases in Aryl and CTRCD tended in the same direction but were of borderline statistical significance (HR: 1.17; 95% CI: 0.99-1.38; P = 0.071). In patients with breast cancer treated with doxorubicin with or without trastuzumab, increases in the Pon enzymatic activity level of PON-1 were associated with increased CTRCD risk. PON-1 activity may be relevant to mechanistic risk prediction of cardiotoxicity with anthracyclines.

Association of PON1 gene polymorphisms and enzymatic activity with risk of coronary artery disease

Background: The present case-control study evaluated the association of PON1 gene polymorphisms and enzyme activity in the western Indian population. Materials & methods: Angiographically proven coronary artery disease (CAD) formed the cases. PON1 polymorphisms (Q192R, L55M) and enzymatic activity (paraoxonase) were assessed. Results: A total of 502 participants (251 per group) were studied. PON1 Q192R and L55M polymorphisms were not associated with the risk of CAD. Notably, a weak association was observed between Q192R polymorphisms and the risk of CAD. CAD patients had significantly lower PON1 enzymatic activity (U/L) as compared with the controls regardless of the genotype. Conclusion: Low serum PON1 activity was confirmed to be an independent predictor for the risk of CAD.

Arylesterase Activity of Paraoxonase-1 in Serum and Cerebrospinal Fluid of Patients with Alzheimer's Disease and Vascular Dementia

BACKGROUND

It has been suggested that circulating Paraoxonase-1 (PON1) and apolipoprotein A1 (APOA1), which closely interacts with the antioxidant enzyme, could be implicated in Alzheimer's disease (AD) and vascular dementia (VaD) development. This study aimed to evaluate PON1 changes in serum and cerebrospinal fluid (CSF) as evidence for its association with AD or VaD.

METHODS

Serum PON-arylesterase activity was measured in patients with AD, VaD, and CONTROLS distributed in two cohorts: Ferrara cohort (FC: n = 503, age = 74 years) and Amsterdam Dementia cohort (ADC: n = 71, age = 65 years). In the last cohort, CSF PON-arylesterase, CSF β-amyloid1-42, p-tau and t-tau, and imaging biomarkers were also measured.

RESULTS

AD and VaD patients of FC showed significantly lower levels of serum PON-arylesterase compared to CONTROLS, but this outcome was driven by older subjects (>71 years, p < 0.0001). In the younger ADC, a similar decreasing (but not significant) trend was observed in serum and CSF. Intriguingly, PON-arylesterase per APOA1 correlated with t-tau in AD group (r = -0.485, p = 0.002).

CONCLUSION

These results suggest that decreased peripheral PON-arylesterase might be a specific feature of older AD/VaD patients. Moreover, we showed that PON-arylesterase/APOA1 is inversely related to neurodegeneration in AD patients, suggesting a prognostic usefulness of this composite parameter.

PON1 lactonase activity and its association with cardiovascular disease

BACKGROUND

Paraoxonase 1 (PON1) is important in the development of atherosclerosis, and it has become the subject of intensive research. Our aim was to evaluate the association of serum PON1 activity and polymorphisms with cardiovascular disease (CVD) using four different substrates.

MATERIALS AND METHODS

Activity of PON1-related to arylesterase (AREase and 4-CMPAse), paraoxonase (PONase), and lactonase (LACase), and polymorphisms (A-162G, T-108C, L55M, and Q192R) were evaluated in subjects with CVD, cardiovascular risk factor (CFR), and controls. An ordered logistic-regression analysis of PON1 phenotypes was performed in the CVD group with respect to the control group.

RESULTS AND CONCLUSIONS

Logistic-regression analysis showed that CC-108 genotype was associated with CRF and CVD. The CVD group had the lowest activities of PON1. The LACase might be a better biomarker for CVD (OR, 0.52; 95% CI, 0.44-0.61) followed by CMPAse (OR, 0.82; 95% CI, 0.77-0.86), AREase (OR, 0.98; 95% CI, 0.97-0.99) and PONase (OR, 0.99, 95% CI, 0.99-0.99). Logistic regression of PON1 phenotypes by haplotypes showed that LACase activity was not influenced by the polymorphisms and that it could be a new potential biomarker in the development of CVD. Larger scale longitudinal studies are required.

Crosstalk Between Adipokines and Paraoxonase 1: A New Potential Axis Linking Oxidative Stress and Inflammation

Paraoxonase 1 (PON1) is a high-density lipoprotein (HDL)-associated protein that endows its carrier with (lipo-)lactonase-dependent antioxidative features. Low levels of PON1 activity have been observed in association with obesity, a major risk factor for cardiovascular disease (CVD). Considering the well-recognized atheroprotective role of PON1, exogenous/endogenous factors that might modulate its levels/activity are raising great interest. Since adipokines represent a molecular link between obesity and CVD, we here explored the possible impact of these substances on PON1 activity/expression. The levels of interleukin (IL)-6, IL-8, tumor necrosis factor alpha, monocyte chemoattractant protein-1, hepatocyte growth factor, resistin, leptin, and adiponectin were measured along with arylesterase, paraoxonase, and lactonase activities of PON1 in 107 postmenopausal women. Moreover, the direct effect of resistin on PON1 expression was evaluated in vitro. Multivariate analysis revealed that only resistin was significantly and inversely correlated with PON1-lactonase activities (r = −0.346, p < 0.001) regardless of confounding factors such as age or HDL-cholesterol. It is worth noting that no statistical link was found between adipokine and arylesterase or paraoxonase, the two promiscuous activities of PON1. Notably, resistin down-regulated PON1 expression occurred in hepatocellular carcinoma cultures. Our study suggests that resistin might be a negative modulator of PON1 expression and anti-oxidative activity.

Paraoxonase-1 activities in individuals with different HDL circulating levels: Implication in reverse cholesterol transport and early vascular damage

BACKGROUND AND AIMS

Epidemiological data showing that high-density lipoprotein cholesterol (HDL-C) is inversely associated with cardiovascular disease have led to the idea that cholesterol contained in this lipoprotein may be protective. Against, recent evidence suggests that the athero-protection from HDLs may result from other functions, unrelated to the carried cholesterol. HDL accessory proteins, such as paraoxonase 1 (PON1), have been suggested to endows HDL with antioxidant and anti-inflammatory properties and to contribute to the athero-protective function of the lipoprotein. We aimed to evaluate whether extreme fluctuation in HDL-C levels correlates with PON1 activity.

METHODS

Levels of PON1-related arylesterase and lactonase were assessed in subjects with primary hyperalphalipoproteinemia (HAL, HDL-C>90th percentile), hypoalphalipoproteinemia (HA, HDL-C<10th percentile) and controls. Cholesterol efflux capacity (CEC) through several pathways and other metabolic parameters and markers of vascular disease were also determined.

RESULTS

Despite the marked change in HDL-C and Apoliprotein A1 (APO A1) (p < 0.001 for all comparisons), arylesterase and lactonase were only slightly increased in HAL compared with HA subjects (p < 0.05), but not vs. controls. This change in PON1 activities was no longer significant after adjustment for either HDL-C or APO A1. Both enzymatic activities were positively associated only with aqueous diffusion CEC (r = 0.318, p < 0.05 and r = 0.355, p < 0.05, respectively) and negatively with the presence of plaques (p < 0.05).

CONCLUSIONS

We showed that extreme high/low HDL-C levels are not associated with equal increase/decrease in PON1 activities. This enzyme appears to contribute to the HDL role in reverse cholesterol transport and anti-atherosclerosis processes. Further investigation is required to corroborate our findings.

Associations of the PON1 rs854560 polymorphism with plasma lipid levels: a meta-analysis

Background

Previous studies have investigated the associations of paraoxonase 1 (PON1) rs854560 polymorphism with plasma lipid levels, but the results are inconclusive. This meta-analysis aimed to clarify the associations of the rs854560 polymorphism with plasma lipid levels.

Methods

A comprehensive search of the literature was carried out by using the databases which include Medline, Google Scholar, Web of Science, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang and VIP database up till August 2018. The pooled standardized mean difference (SMD) with 95% confidence interval (CI) was used to assess the differences in lipid levels between the genotypes. Begg’s funnel plots and Egger’s test were used to examine the publication bias.

Results

A total of 41 studies (22,844 subjects) were identified for the associations of rs854560 polymorphism with plasma lipid levels. The M carriers had lower levels of high-density lipoprotein Cholesterol (HDL-C) (SMD = − 0.15, 95% CI = − 0.23--0.07, P < 0.01) and apolipoprotein A-I (APOA1) (SMD = − 0.67, 95% CI = − 0.93--0.41, P < 0.01) than the non-carriers. Subgroup analysis by ethnicity revealed that the effect on HDL level was significant in Caucasians and the subjects of other ethnic origins. No publication bias was detected in this meta-analysis.

Conclusions

The meta-analysis suggests that the PON1 rs854560 polymorphism is associated with a lower HDL-C level in Caucasians and subjects of other ethnic origins.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0924-0) contains supplementary material, which is available to authorized users.

TRAIL and Ceruloplasmin Inverse Correlation as a Representative Crosstalk between Inflammation and Oxidative Stress

Objective

“Oxinflammation” is a recently coined term that defines the deleterious crosstalk between inflammatory and redox systemic processes, which underlie several diseases. Oxinflammation could be latently responsible for the predisposition of certain healthy individuals to disease development. The oxinflammatory pathway has been recently suggested to play a crucial role in regulating the activity of TNF-related apoptosis-inducing ligand (TRAIL), a TNF superfamily member that can mediate multiple signals in physiological and pathological processes. Therefore, we investigated the associations between TRAIL and key players of vascular redox homeostasis.

Methods

We measured circulating TRAIL levels relative to praoxonas-1, lipoprotein phospholipase-A2, and ceruloplasmin levels in a cohort of healthy subjects (n = 209).

Results

Multivariate analysis revealed that ceruloplasmin levels were significantly inversely associated with TRAIL levels (r = −0.431, p < 0.001). The observed association retained statistical significance after adjustment for additional confounding factors. After stratification for high-sensitivity C-reactive protein levels, the inverse association between TRAIL and ceruloplasmin levels remained strong and significant (r = −0.508, p < 0.001, R² = 0.260) only in the presence of inflammation, confirming the role of inflammation as emerged in in vitro experiments where recombinant TRAIL decreased ceruloplasmin expression levels in TNF-treated PBMC cultures.

Conclusion

The results indicated that in an inflammatory milieu, TRAIL downregulates ceruloplasmin expression, highlighting a signaling axis involving TRAIL and ceruloplasmin that are linked via inflammation and providing important insights with potential clinical implications.

Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

Serum paraoxonase-1 activity is inversely related to free thyroxine in euthyroid subjects: The PREVEND Cohort Study

BACKGROUND

Low-normal thyroid function within the euthyroid range has been suggested to enhance atherosclerosis susceptibility. Paraoxonase-1 (PON-1) may protect against atherosclerotic cardiovascular disease development by attenuating oxidative stress. We evaluated relationships of PON-1 with thyroid stimulating hormone (TSH), free T₄ , free T₃ , lipids and apolipoprotein (apo)A-I in euthyroid subjects, and assessed whether such relationships are modified in the context of the metabolic syndrome (MetS).

MATERIALS AND METHODS

Serum PON-1 activity (arylesterase activity), TSH, free T₄ , free T₃ , lipids and apoA-I was measured in 2206 euthyroid subjects (aged 28-75 years; 1138 men (age 49 ± 13 years) and 1068 women (age 46 ± 12 years), recruited from the general population (PREVEND cohort).

RESULTS

In age- and sex-adjusted analysis, PON-1 activity (divided into tertiles) was positively related to TSH (β = -0.045, P = .036) and inversely to free T₄ (β = -0.042, P = .050) but not to free T₃ (β = -0.027, P = .20). PON-1 activity was positively related to total cholesterol, non-HDL cholesterol and triglycerides, as well as to HDL cholesterol and apoA-I (P < .01 to <.001). The inverse relationship of PON-1 activity with free T₄ remained present after adjustment for lipids and other potential confounders (β = -0.066, P = .002), but the positive relationship with TSH lost significance (β = 0.034, P = .11). The inverse relationship of PON-1 activity with free T₄ was not different in subjects with vs without MetS (P = .94), nor modified by the presence of its individual components (P ≥ .22 for each).

CONCLUSIONS

Serum PON-1 activity is inversely associated with free T₄ in euthyroid subjects, suggesting that low-normal thyroid function may affect PON-1 regulation.

Dynamic changes of paraoxonase 1 activity towards paroxon and phenyl acetate during coronary artery surgery

BACKGROUND

Serum paraoxonase 1 (PON1), an enzyme associated with high - density lipoproteins (HDL) particles, inhibits the oxidation of serum lipoproteins and cell membranes. PON1 activity is lower in patients with atherosclerosis and in inflammatory diseases. The systemic inflammatory response provoked during cardiopulmonary bypass grafting may contribute to the development of postoperative complications. The aim of the present study was to estimate the dynamic changes in paraoxonase 1 (PON1) activity towards paraoxon and phenyl acetate during and after coronary artery surgery.

METHODS

Twenty six patients with coronary heart disease undergoing coronary artery bypass grafting (CABG) were enrolled into the study. Venous blood samples were obtained preoperatively, after aortic clumping, after the end of operation, at 6, 18, 30 and 48 h after operation. Paraoxonase activity was measured spectrophotometrically in 50 mM glycine/NaOH buffer (pH 10.5) containing 1.0 mM paraoxon, and 1.0 mM CaCl₂. Arylesterase activity was measured in 20 mM TrisCl buffer (pH 8.0) containing 1 mM phenyl acetate and 1 mM CaCl₂.

RESULTS

PON1 activity toward paraoxon and phenyl acetate significantly decreased after aorta cross clumping and increased directly after operation. PON1 activity towards paraoxon in preoperative period and PON1 activity towards phenyl acetate in seventh stage of experiment tended to inversely correlate with the occurrence of postoperative complications.

CONCLUSION

The paraoxonase 1 plasma activity is markedly reduced during CABG surgery.

Astaxanthin in cardiovascular health and disease: mechanisms of action, therapeutic merits, and knowledge gaps

Cardiovascular disease is the main contributor to morbidity and mortality worldwide.

Human paraoxonase-1 (PON1): Gene structure and expression, promiscuous activities and multiple physiological roles

Human PON1 is a HDL-associated lipolactonase capable of preventing LDL and cell membrane oxidation and is therefore considered to be atheroprotective. PON1 contributes to the antioxidative function of HDL and reductions in HDL-PON1 activity, prevalent in a wide variety of diseases with an inflammatory component, are believed to lead to dysfunctional HDL which can promote inflammation and atherosclerosis. However, PON1 is multifunctional and may contribute to other HDL functions such as in innate immunity, preventing infection by quorum sensing gram negative bacteria by destroying acyl lactone mediators of quorum sensing, and putative new roles in cancer development and the promotion of healthy ageing. In this review we explore the physiological roles of PON1 in disease development, as well as PON1 gene and protein structure, promiscuous activities and the roles of SNPs and ethnicity in determining PON1 activity.

The association of paraoxonase 1 gene L55M polymorphism with the extent and severity of coronary artery disease in the Turkish population and its dependence on gender

OBJECTIVE

Coronary artery disease (CAD) is a common, complex, and progressive disorder characterized by the accumulation of lipids and fibrous elements in the arteries. It is one of the leading causes of death in industrialized nations. Oxidative modification of low-density lipoprotein (LDL) in the arterial wall plays an important role in the initiation and progression of atherosclerosis. Paraoxonase1 (PON1) is involved in lipid metabolism and is believed to protect LDL oxidation. In our study, we aimed to clarify the relationship between PON1 gene L55M polymorphism and the extent and severity of CAD.

METHODS

In total, 114 patients (54 males, mean age: 56.7 ± 12.0 years; 60 females, mean age: 55.7 ± 13.2 years) with stable angina or angina equivalent symptoms were enrolled in this prospective study. Cardiological evaluation was performed with electrocardiogram and transthoracic echocardiogram. The presence of hypertension, dyslipidemia, diabetes, and smoking status were ascertained. The patients were grouped according to their Gensini scores and gender. Genetic analysis of the PON1 gene L55M polymorphism was performed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

We determined that the LL genotype was more prevalent in patients with Gensini score higher than or equal to 20 (p=0.026) and that this correlated with severe atherosclerotic coronary artery lesions in both gender groups, reaching a statistical significance in the female subjects (p=0.038).

CONCLUSION

It was thought that the PON1 gene L55M polymorphism plays a significant role in CAD progression, especially in females.

Low paraoxonase 1 arylesterase activity and high von Willebrand factor levels are associated with severe coronary atherosclerosis in patients with non-diabetic stable coronary artery disease

Background

Paraoxonase 1 (PON1) activity and von Willebrand factor (VWF) release are associated with lesion initiation in atherosclerosis. Diabetes can complicate coronary artery disease (CAD) due to the production of advanced glycation end products. This study evaluated PON1 activity and VWF levels in non-post-acute coronary syndrome, stable CAD (SCAD) patients without diabetes.

Material/Methods

Non-diabetic SCAD patients and patients experiencing acute stress periods were selected (n=130). Forty-seven cases with normal coronary angiography and 50 healthy individuals served as controls. The non-diabetic SCAD group was then stratified into single-vessel lesions, multiple-vessel lesions, and mild or severe luminal stenosis according to the number and the degree of luminal stenoses. Serum PON1 paraoxonase and arylesterase activities, and plasma VWF levels were measured, as well as serum total cholesterol, total triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and apolipoprotein A1. PON1 arylesterase activity was detected with an ordinary chemistry system using a novel phenylacetate derivative.

Results

Both PON1 paraoxonase and arylesterase were lower in the non-diabetic SCAD group, but VWF levels were higher (versus controls, all P<0.001). PON1 paraoxonase activity (OR=0.991), PON1 arylesterase activity (OR=0.981), and VWF (OR 2.854) influenced SCAD in multiple logistic regression. Decreased PON1 arylesterase activity and increased VWF levels were associated with severe atherosclerosis in non-diabetic SCAD patients. We also observed a slight negative correlation between VWF and PON1 paraoxonase/arylesterase.

Conclusions

PON1 and VWF are detectable markers that may predict the severity of stenoses, ideally facilitating a non-diabetic SCAD diagnosis before the sudden onset of life-threatening symptoms.

Plasma paraoxonase 1 arylesterase activity in D-galactose-induced aged rat model: correlation with LDL oxidation and redox status

OBJECTIVE

There is much evidence linking the involvement of oxidative stress in the pathogenesis of aging. Paraoxonase 1 (PON1) is an HDL-associated antioxidant enzyme that inhibits the oxidative modification of low-density lipoproteins (LDL). We have investigated the changes in plasma PON1 activity, LDL oxidation, radical scavenging activity and lipid peroxidation in D-galactose-induced aging rat model and also compared the results with 24-month naturally aged rats.

METHOD

Arylesterase activity of PON1, susceptibility of LDL for oxidation, plasma radical scavenging activity and plasma thiobarbituric acid reactive substances (TBARS) were measured in normal control rats (4-months-old control rats subjected to D-galactose-induced experimental aging, and 24-month-old naturally aged rats).

RESULTS

There was a significant decrease in plasma PON1 arylesterase activity in both subcutaneous D-galactose-treated groups and 24-month-old aged rats (P < 0.05, for each). TBARS, an oxidative stress marker, was seen to increase in the experimental groups (P < 0.01). In both subcutaneous galactose-treated and naturally aged rats, there was a significant rise in plasma LDL oxidation (P < 0.05, for each). However, radical scavenging activity was decreased significantly (P < 0.01) in both groups, as compared to control.

CONCLUSIONS

The D-galactose-induced rat model of aging mimics the naturally aged rat with reference to PON1 arylesterase activity and susceptibility to LDL oxidation. The results emphasize the importance of PON1 with respect to aging and its association with redox balance of the body.

Impacts of chloramine-T treatment on antioxidant enzyme activities and genotoxicity in rainbow trout, Oncorhynchus mykiss (Walbaum)

Juvenile rainbow trout Oncorhynchus mykiss (Walbaum) were exposed to therapeutic, and higher concentrations of chloramine-T (Cl-T) to assess the effects of this chemical on the antioxidant enzyme system and genetic structure. Red blood cells acetylcholinesterase, ∆-aminolevulinic acid dehydratase, paraoxonase and liver glutathione S-transferase activity were increased at 10 and 20 mg L(-1) Cl-T-exposed fish, while they were decreased at 30 mg L(-1) Cl-T-exposed fish. On the other hand, liver catalase activity and liver protein levels increased at 10 mg L(-1) and decreased at 20 and 30 mg L(-1) concentrations of Cl-T. Liver super-oxide dismutase activity decreased at 10 mg L(-1) and 20 mg L(-1) Cl-T and increased at 30 mg L(-1) of Cl-T. Compared to control, comet assay indicated that Cl-T did not cause significant DNA damage to red blood cells of the fish. Results indicate that 10 or 20 mg L(-1) Cl-T can be safely used to prevent or treat external parasitic and bacterial infection of rainbow trout.

High-density lipoprotein impedes glycation of low-density lipoprotein

Glycation of low-density lipoprotein (LDL) increases its atherogenicity, but whether high-density lipoprotein (HDL) can protect LDL against glycation is not known. LDL and HDL were isolated from 32 volunteers with serum HDL cholesterol concentrations ranging from 0.76 to 2.01 (mean = 1.36) mmol/L. Glycation of LDL was induced by incubation with 0-80 mmol/L glucose for 7 days at 37°C under nitrogen in the presence of and absence of human HDL. Glycation of LDL apolipoprotein B (apoB) doubled at glucose 50 and 80 mmol/L (both p < 0.001), and this increase was ameliorated by HDL. In the absence of glucose, 0.11 (0.01) [mean (standard error, SE)] mg apoB/mg LDL protein was glycated increasing to 0.22 (0.02) mg/mg at glucose 80 mmol/L in the absence of HDL, but remaining at 0.13 (0.01) mg/mg when autologous HDL was present. Heterologous HDL from a further study of 12 healthy participants was similarly effective in impeding LDL apoB glycation. HDL impeded not only glycation but also the lipid peroxidation, free amino group consumption and increased electrophoretic mobility of LDL which accompanied glycation. HDL from participants with higher serum paraoxonase1 (PON1) was more effective in impeding glycation and the related processes. In conclusion, HDL can impede the glucose-induced glycoxidation of LDL. PON1 may be important for this function of HDL.

Paraoxonase-1 (PON1) promoter region polymorphisms, serum PON1 status and coronary heart disease

INTRODUCTION

Serum paraoxonase-1 (PON1) retards the oxidation of low-density lipoprotein and cell membranes and is atheroprotective. Polymorphisms in the promoter region of the PON1 gene have been shown to affect serum PON1 levels and have been related to the presence of coronary heart disease (CHD) in some studies. However, contradictory results have been reported with regard to promoter region polymorphisms and CHD presence; therefore we have re-examined the effects of the C-108T and G-909C promoter polymorphisms on PON1 levels and the presence of CHD in a large case-control study.

MATERIAL AND METHODS

Paraoxonase-1 activity, concentration and the C-108T and G-909C polymorphisms were measured in 417 people with CHD and 282 healthy controls, in a case control study.

RESULTS

Paraoxonase-1 activity and concentration were significantly lower in the CHD population compared to controls regardless of their C-108T and G-909C genotype (p < 0.001). Paraoxonase-1 activity was significantly different in the C-108T genotypes in both the control and CHD groups in the order TT < TC < CC (p < 0.01). Paraoxonase-1 concentration was significantly different in the CHD group only in the G-909C genotype in the order GG > GC > CC (p < 0.01). Haplotype analysis revealed no consistent patterns of PON1 activity in the CHD population; however, in the controls PON1 activity differed between haplotypes GGCC > GGTC > GGTT (p < 0.05) and GCCC > GCTC > GCTT (p < 0.02). Neither promoter polymorphism was associated with CHD presence.

CONCLUSIONS

Paraoxonase-1 status was significantly lower in people with CHD and was affected by the promoter region polymorphisms.

Serum Paraoxonase (PON1) Activity in North-West Indian Punjabi's with Acute Myocardial Infarction

Human serum paraoxonase-1 (PON1), an enzyme on HDL prevents oxidation of LDL thereby preventing the development of atherosclerosis. Studies done so far have lead to conflicting results. As studies are lacking in North-West Indian Punjabi's, a distinct ethnic group with high incidence of coronary artery disease, we determined PONase activity in this population. It has been postulated that sudden lowering of serum PONase may lead to precipitation of acute myocardial infarction. We determined serum PONase activity and lipids in 100 patients each of AMI (within 24 h of onset), stable CAD and 100 age and sex matched healthy controls. These were again determined after 6 weeks in AMI patients. The mean serum PONase activity was lowest in AMI patients (23.26 U/ml) followed by stable CAD patients (102.0 U/ml) where as in controls was highest (179.8 U/ml). In patients with AMI, activity was significantly higher at 6 weeks as compared to that after acute event (49.39 %; p < 0.05). Sudden lowering of serum PONase activity in a population which already has lower activity may be one of the risk factors for development of AMI.

Quantitative assessment of the influence of paraoxonase 1 activity and coronary heart disease risk

Human paraoxonase 1 (PON1) is a calcium-dependent high-density lipoprotein associated ester hydrolase that has attracted considerable attention as a candidate factor for coronary heart disease (CHD) based on its function as a key factor in lipoprotein catabolism pathways. This meta-analysis aimed to clarify the inconsistency of published studies and to establish a comprehensive picture of the relationship between PON1 activity and CHD susceptibility. A systematic search was performed from PubMed, Web of Science, EMBASE, and CNKI databases. Ratio of means (RoM) between case and control and 95% confidence intervals (CIs) were calculated using a random-effects model. The source of heterogeneity was explored by subgroup analysis and meta-regression. We identified 47 eligible studies including a total of 9853 CHD cases and 11,408 controls. The pooled analysis showed that CHD patients had a 19% lower PON1 activity than did the controls (RoM=0.81; 95% CI: 0.74-0.89, p<10(-5)). In the subgroup analyses by CHD end points, a similar effect size was observed with coronary stenosis and myocardial infarction subgroups, with corresponding RoM of 0.81 (95% CI: 0.73-0.89, p<10(-4)) and 0.83 (95% CI: 0.74-0.93, p=0.001), respectively. Decreased PON1 activity associated with CHD risk was observed in almost all subgroup analysis according to ethnicity, sample size, study design, mean age of cases, source, and type of control. Decreased PON1 activity may act as a risk factor for the development of CHD. Progressive decrease in serum PON1 activity may exist for an individual with severe disease. However, larger studies using a prospective approach are needed to confirm our results.

Association between PON1 activity and coronary heart disease risk: a meta-analysis based on 43 studies

Paraoxonase 1 (PON1) is reported to have antioxidant and cardioprotective properties. The relationship between PON1 activity and coronary heart disease (CHD) risk in humans has been reported among various ethnic populations in the past decade. However, these studies have yielded contradictory results. To investigate this inconsistency, we conducted a meta-analysis of 43 studies involving a total of 20,629 subjects to evaluate the effect of PON1 activity on susceptibility for CHD. We also systematically explored potential sources of heterogeneity using subgroup analysis and meta-regression. Significant decreases paraoxonase activity of PON1 were observed in CHD patients compared with non-CHD controls with SMD of -0.78 (95% CI: -0.98, -0.57; P<0.001). Similar results were also found for arylesterase activity of PON1 with SMD of -0.50 (95% CI: -0.64, -0.36; P<0.001). In the subgroup analysis by ethnicity, CHD phenotype, sample size, source of controls, mean age and BMI of cases, significantly increased risks were also found. In addition, our analyses detected a possibility of publication bias with an overestimate of the true association by smaller studies. This meta-analysis demonstrated that decreasing in PON1 activity is a risk factor associated with increased CHD susceptibility. However, additional very large-scale studies are warranted to provide conclusive evidence on the effects of PON1 activity on risk of CHD.

Serum PON-1 activity but not Q192R polymorphism is related to the extent of atherosclerosis

AIM

Paraoxonase-1 (PON1) is an antioxidant enzyme located in high density lipoprotein (HDL). PON1 was defined as a protective factor against atherosclerosis. The aim of this study was to investigate the possible relationship between serum paraoxonase (PONase), homocysteine thiolactonase (HTase) activities and PON1 Q192R polymorphism, and the extent and severity of atherosclerosis.

METHODS

Blood specimens were collected from 142 individuals who had no coronary artery lesions angiographically (control group) and 128 individuals who had angiographically documented coronary artery disease of several degrees (patient group). The extent and severity of arterial lesions were evaluated by the Gensini scoring system. PONase and HTase activities were measured in serum using a spectrophotometric method. PON1 Q192R polymorphism was evaluated using PCR-RFLP after DNA isolation from blood.

RESULTS

Serum PONase and HTase activities were significantly lower in the patient group than in healthy controls (135.7±56.0U/mL vs 153.8±62.0U/mL, p< 0.05; 36.0±6.1 U/mL vs 43.0±4.04 U/mL, p< 0.01; respectively). In the patient group, there was a negative correlation between PONase, HTase activities and the Gensini score (r=-0.168, p= 0.039; r=-0.164, p= 0.006, respectively). In both groups, there was no significant difference in the distribution of PON1 Q192R polymorphism. In the patient group, the distribution of Gensini scores according to genotypes was not significant.

CONCLUSION

It has been concluded that serum PONase and HTase activities might be a more relevant marker than PON1 genotype in evaluating the extent and severity of atherosclerosis.

Proteomics of Lipoprotein(a) identifies a protein complement associated with response to wounding

Lipoprotein(a) [Lp(a)] is a major independent risk factor for cardiovascular disease. Twenty percent of the general population exhibit levels above the risk threshold highlighting the importance for clinical and basic research. Comprehensive proteomics of human Lp(a) will provide significant insights into Lp(a) physiology and pathogenicity. Using liquid chromatography-coupled mass spectrometry, we established a high confidence Lp(a) proteome of 35 proteins from highly purified particles. Protein interaction network analysis and functional clustering revealed proteins assigned to the two major biological processes of lipid metabolism and response to wounding. The latter includes the processes of coagulation, complement activation and inflammatory response. Furthermore, absolute protein quantification of apoB-100, apo(a), apoA1, complement C3 and PON1 gave insights into the compositional stoichiometry of associated proteins per particle. Our proteomics study has identified Lp(a)-associated proteins that support a suggested role of Lp(a) in response to wounding which points to mechanisms of Lp(a) pathogenicity at sites of vascular injury and atherosclerotic lesions. This study has identified a high confidence Lp(a) proteome and provides an important basis for further comparative and quantitative analyses of Lp(a) isolated from greater numbers of plasma samples to investigate the significance of associated proteins and their dynamics for Lp(a) pathogenicity.

Persistent elevation of paraoxonase-1 specific enzyme activity after weight reduction in obese non-diabetic men with metabolic syndrome

BACKGROUND

Paraoxonase-1 (PON1) is an esterase associated with the high-density lipoprotein (HDL) in serum. To date, there have been few reports about circulating PON1 protein concentration and specific activity in subjects with metabolic syndrome (MetS). More importantly, it is unknown whether weight loss could alter PON1 protein expression or specific activity in obese non-diabetic men with MetS.

METHODS

We prospectively enrolled a total of 40 obese non-diabetic men with MetS. Among them, 22 subjects finished the 3-month course of weight loss program and complied for longer follow-ups post-weight loss at the 3rd, 12th, and 18th month from the beginning of the program. Twenty-six healthy volunteers served as controls. Serum circulating PON1 concentration was measured by an enzyme linked immunosorbent kit (ELISA) and PON1 activity was measured by an automated PON1 activity assay.

RESULTS

Obese non-diabetic men with MetS (n=40) had a higher PON1 protein concentration (31.0 ± 11.3 vs. 24.8 ± 9.7 μg/ml, p=0.025) but lower specific enzyme activity (7.5 ± 4.0 vs. 11.2 ± 7.2 mU/μg, p=0.023) than those of the controls. Multivariate regression analysis of baseline PON1 specific activity revealed that adiponectin was a significant positive predictor (p=0.044) while monocyte chemotactic protein-1 (MCP-1) was a negative predictor (p=0.031). After a 3-month weight loss program, obese MetS men (n=22) had a significant weight reduction (95.8 ± 9.0 to 86.3 ± 10.4 kg, with a 9.9 ± 5.4% decrease, p<0.001). PON1 protein decreased significantly after weight loss and kept declining through the 3rd month till the 18th month follow-up. PON1 specific enzyme activity (baseline 7.5 ± 2.6 mU/μg) increased significantly after weight loss and kept increasing through the 12th month till the 18th month follow-ups (11.8 ± 6.4 mU/μg, p=0.001 vs. baseline).

CONCLUSIONS

Weight loss by a 3-month diet and exercise program time-sequentially increased PON1 specific enzyme activity in obese non-diabetic men with MetS.

Four genetic polymorphisms of paraoxonase gene and risk of coronary heart disease: a meta-analysis based on 88 case-control studies

OBJECTIVE

The human paraoxonase (PON) is calcium dependent HDL associated ester hydrolase which has attracted considerable attention as a candidate gene for coronary heart disease based on its enzyme function as a key factor in lipoprotein catabolism pathways. Many studies have examined the association between polymorphisms in the PON gene and risk of coronary heart disease (CHD), but the results have been inconsistent.

METHODS

We conducted a meta-analysis of 88 studies on 4 PON polymorphisms [Q192R, L55M, and T(-107)C in the PON1 and the S311C in the PON2] published before August 2010, including a total of 24,702 CHD cases and 38,232 controls. We also systematically explored potential sources of heterogeneity.

RESULT

In a combined analysis, the summary per-allele odds ratio for CHD of the 192R was 1.11 (95% CI: 1.05-1.17). However, when the analyses were restricted to 10 larger studies (n>500 cases), the summary per-allele odds ratio was 0.96 (95% CI: 0.90-1.02). Our analyses detected a possibility of publication bias with an overestimate of the true association by smaller studies. A meta-analysis of studies on the 55M, (-107)T, and 311C variant showed no significant overall association with CHD, yielding a per-allele odds ratio of 0.94 (95% CI: 0.88-1.00), 1.02 (95% CI: 0.91-1.15) and 1.02 (95% CI: 0.90-1.16) respectively.

CONCLUSIONS

This meta-analysis suggested an overall weak association between the R192 polymorphism and CHD risk.

Both paraoxonase-1 genotype and activity do not predict the risk of future coronary artery disease; the EPIC-Norfolk Prospective Population Study

Background

Paraoxonase-1 (PON1) is an antioxidant enzyme, that resides on high-density lipoprotein (HDL). PON1-activity, is heavily influenced by the PON1-Q192R polymorphism. PON1 is considered to protect against atherosclerosis, but it is unclear whether this relation is independent of its carrier, HDL. In order to evaluate the atheroprotective potential of PON1, we assessed the relationships among PON1-genotype, PON1-activity and risk of future coronary artery disease (CAD), in a large prospective case-control study.

Methodology/Principal Findings

Cases (n = 1138) were apparently healthy men and women aged 45–79 years who developed fatal or nonfatal CAD during a mean follow-up of 6 years. Controls (n = 2237) were matched by age, sex and enrollment time. PON1-activity was similar in cases and controls (60.7±45.3 versus 62.6±45.8 U/L, p = 0.3) and correlated with HDL-cholesterol levels (r = 0.16, p<0.0001). The PON1-Q192R polymorphism had a profound impact on PON1-activity, but did not predict CAD risk (Odds Ratio [OR] per R allele 0.98[0.84–1.15], p = 0.8). Using conditional logistic regression, quartiles of PON1-activity showed a modest inverse relation with CAD risk (OR for the highest versus the lowest quartile 0.77[0.63–0.95], p = 0.01; p-trend = 0.06). PON1-activity adjusted for Q192R polymorphism correlated better with HDL-cholesterol (r = 0.26, p<0.0001) and more linearly predicted CAD risk (0.79[0.64–0.98], p = 0.03; p-trend = 0.008). However, these relationships were abolished after adjustment for HDL (particles-cholesterol-size) and apolipoproteinA-I (0.94[0.74–1.18], p-trend = 0.3).

Conclusions/Significance

This study, shows that PON1-activity inversely relates to CAD risk, but not independent of HDL, due to its close association with the HDL-particle. These data strongly suggest that a low PON1-activity is not a causal factor in atherogenesis.