Paraoxonase 1 activities, regulation, and interactions with atherosclerotic lesion

PON1 has palmitoyl-protein thioesterase (PPT) activity, and can affect the presence of SR-B1 on the endothelial cell membrane

The high-density lipoprotein (HDL)-associated enzyme paraoxonase 1 (PON1) is expressed almost exclusively in the liver and is then transported by HDL to the peripheral tissues. The lipophilic nature of PON1 enables its easy exchange between the lipoprotein and cell membranes in a process that is dependent on the HDL receptor scavenger receptor class B, type 1 (SR-B1). In endothelial cells, PON1 binding to the cell membrane leads to its internalization by endocytosis and subsequent lysosomal degradation. PON1 is a "promiscuous" enzyme with unusually broad substrate specificity in vitro, but its actual function and substrate are still unknown. The enzyme requires a lipid environment and becomes completely inactive upon delipidation. However, when PON1 binds HDL, its active site faces the lipoprotein's core and is inaccessible to external substrates. Hence, the HDL-bound PON1 is inactive toward substrates outside the particle's lipid core and is rapidly degraded and becomes inactive upon internalization. Consequently, the enzyme is only active in the cell membrane during its transit from HDL to the cytoplasm. To assign a function to PON1, we investigated whether it is a palmitoyl-protein thioesterase (PPT) that can hydrolyze the palmitoyl moieties of membrane proteins involved in HDL and cholesterol transport, such as SR-B1, ABCA1, or their neighboring caveola proteins to facilitate the release of HDL or trigger its endocytosis. This study shows that PON1 can hydrolyze palmitoyl-cysteine thioester bonds in vitro, has direct or indirect PPT activity in vivo, and can significantly decrease the presence of SR-B1 in the endothelial membrane.

Echinacea purpurea extract intervention for counteracting neurochemical and behavioral changes induced by bifenthrin

This study was conducted to elucidate the possible protective efficiency of Echinacea purpurea hydroethanolic extract (EchEE) against bifenthrin (BIF)-induced neuro-chemical and behavioral changes in rats. Total phenolics content, reducing power and radical scavenging activity of EchEE were estimated. Four groups of adult male albino rats were used (10 rats each) as follows: 1) Control healthy rats ingested with placebo, 2) Healthy rats orally received EchEE (465 mg/kg/day), 3) Rats intoxicated with BIF (7mg/kg/day) dissolved in olive oil, and 4) Rats co-treated with EchEE (465 mg/kg/day) besides to BIF (7mg/kg/day) intoxication. After 30 days, some neuro-chemical and behavioral tests were assessed. The behavioral tests revealed that rats received BIF exhibited exploratory behavior and spatial learning impairments, memory and locomotion dysfunction, and enhanced anxiety level. Biochemical findings revealed that BIF induced-oxidative stress in the cortex and hippocampus; this was appeared from the significant rise in malondialdehyde (MDA) and nitric oxide (NO) levels, coupled with decreased catalase (CAT), superoxide dismutase (SOD), paraoxonase-1 (PON-1) activities, and reduced glutathione (GSH) level in both brain areas. Also, BIF induced a significant increase caspas-3, tumor necrosis factor alpha (TNF), and interleukin-1beta (IL-1ß) in both areas; dopamine and serotonin levels, and ACh-ase activity were markedly decreased in both areas. Interestingly, treatment of rats with EchEE in combination with BIF resulted in a significant decrease in oxidative stress damage, and modulation of the apoptotic and pro-inflammatory markers. Also, EchEE markedly improved behavioral activities and neurotransmitters level that were impaired by BIF. In conclusion, the present study clearly indicated that EchEE can attenuate brain dysfunction induced by pesticides exposure through preventing the oxidative stress. This may be attributed to its high antioxidant component.

Longitudinal changes of oxidative stress and PON1 lactonase activity and status in older pregnant women undergoing assisted reproductive technology: a prospective nested case-control study

BACKGROUND

Childbearing in women with advanced maternal age (AMA) has increased the need for artificial reproductive technology (ART). ART and oxidative stress are associated with many pregnancy complications. Paraoxonase (PON) 1 is one of the key components responsible for antioxidative activity in high-density lipoprotein (HDL). This study aimed to investigate the longitudinal changes of oxidative stress and PON1 lactonase activity and status in older women undergoing ART.

METHODS

This prospective nested case-control study included 129 control and 64 ART women. Blood samples were obtained respectively at different stages of pregnancy. PON1 level and lactonase activity were assessed using 7-O-diethylphosphoryl-3-cyano-4-methyl-7-hydroxycoumarin (DEPCyMC) and 5-thiobutyl butyrolactone (TBBL) as a substrate, respectively. A normalized lactonase activity (NLA) was estimated based on the ratio of TBBLase to DEPCyMCase activity. Serum total oxidant status (TOS), total antioxidant capacity (TAC), malondialdehyde (MDA), homocysteine (HCY), PON1 C-108T and Q192R genetic polymorphisms, and metabolic parameters were analyzed.

RESULTS

Lactonase activity and level of PON1 gradually decreased with pregnancy progression, while glycolipid metabolism parameters and TAC levels increased with pregnancy progression or significantly raised during the 2nd and 3rd trimesters, and NLA of PON1, TOS, OSI, MDA, and HCY significantly increased before delivery in the ART and control groups. Compared with the control women, the ART women had substantially higher or relatively high lactonase activity and NLA of PON1 and TAC during pregnancy; higher triglyceride (TG), total cholesterol, low-density lipoprotein cholesterol, atherogenic index, apolipoprotein (apo) B, and apoB/apoA1 ratio in the 1st trimester; and higher fasting glucose, fasting insulin, homeostatic model assessment of insulin resistance, and TG levels before delivery. No significant differences were found in the frequencies of PON1 C-108T and Q192R genotypes and alleles between the ART and control groups.

CONCLUSIONS

Women with AMA undergoing ART had higher TAC, PON1 lactonase activity, and PON1 NLA than control women, suggesting increased compensatory antioxidant capacity in ART women, thus showing higher sensitivity to oxidative stress-related injury and diseases.

Paraoxonase 1 Activity and Renal Replacement Therapy for Chronic Renal Failure: A Meta-Analysis

Chronic renal failure (CRF) is associated with the development of cardiovascular disease (CVD). Paraoxonase 1 (PON1), an antioxidant enzyme, shows cardioprotective properties and has been proposed as a therapeutic marker for CRF. A systematic analysis of the literature assessing the association between PON1 activity and renal replacement therapy (RRT) of CRF is currently lacking. Therefore, we set out to perform a meta-analysis of the available data on PON1 in RRT of CRF. We searched three electronic databases for studies on PON1 activity in CRF patients with RRT such as hemodialysis (HD), peritoneal dialysis (PD), or renal transplantation (RTx), published before June 2023. A random-effects and network meta-analysis were performed. A total of 53 studies were eligibly identified. Compared to CRF patients without RRT, RTx patients had higher paraoxonase activity (standard mean difference (SMD), 1.76, 95% confidence interval (CI), 0.76-2.75), followed by HD (SMD, 0.73; 95% CI, 0.02-1.45) and PD patients. Likewise, RTx patients had higher arylesterase activity (SMD, 1.84, 95% CI, 0.18-3.50), followed by HD and PD patients. Also, paraoxonase activity was increased after HD (SMD, 0.59, 95% CI, 0.16-1.03). In conclusion, the overall data demonstrated that PON1 activity is higher in CRF patients with RRT, particularly RTx, followed by that of HD and PD. Measuring PON1 activity can also be included to the paraclinical toolbox for the management of RRT, in addition to the understanding of CRF-related pathophysiology. Regarding the selection of RRT types and their potential to prevent CVD, more research is required.

Modulatory Effect of Lifestyle-Related, Environmental and Genetic Factors on Paraoxonase-1 Activity: A Review

Paraoxonase-1 (PON1) is a calcium-dependent, HDL-bound serum hydrolase active toward a wide variety of substrates. PON1 displays three types of activities, among which lactonase, paraoxonase, arylesterase and phosphotriesterase can be distinguished. Not only is this enzyme a major organophosphate compound detoxifier, but it is also an important constituent of the cellular antioxidant system and has anti-inflammatory and antiatherogenic functions. The concentration and activity of PON1 is highly variable among individuals, and these differences can be both of genetic origin and be a subject of epigenetic regulation. Owing to the fact that, in recent decades, the exposure of humans to an increasing number of different xenobiotics has been continuously rising, the issues concerning the role and activity of PON1 shall be reconsidered with particular attention to growing pharmaceuticals intake, dietary habits and environmental awareness. In the following manuscript, the current state of knowledge concerning the influence of certain modifiable and unmodifiable factors, including smoking, alcohol intake, gender, age and genotype variation on PON1 activity, along with pathways through which these could interfere with the enzyme's protective functions, is presented and discussed. Since exposure to certain xenobiotics plays a key role in PON1 activity, the influence of organophosphates, heavy metals and several pharmaceutical agents is also specified.

Lyso-DGTS Lipid Derivatives Enhance PON1 Activities and Prevent Oxidation of LDL: A Structure–Activity Relationship Study

Paraoxonase 1 (PON1) plays a role in regulating reverse cholesterol transport and has antioxidative, anti-inflammatory, antiapoptotic, vasodilative, and antithrombotic activities. Scientists are currently focused on the modulation of PON1 expression using different pharmacological, nutritional, and lifestyle approaches. We previously isolated a novel active compound from Nannochloropsis microalgae—lyso-diacylglyceryltrimethylhomoserine (lyso-DGTS)—which increased PON1 activity, HDL-cholesterol efflux, and endothelial nitric oxide release. Here, to explore this important lipid moiety’s effect on PON1 activities, we examined the effect of synthesized lipid derivatives and endogenous analogs of lyso-DGTS on PON1 lactonase and arylesterase activities and LDL oxidation using structure–activity relationship (SAR) methods. Six lipids significantly elevated recombinant PON1 (rePON1) lactonase activity in a dose-dependent manner, and four lipids significantly increased rePON1 arylesterase activity. Using tryptophan fluorescence-quenching assay and a molecular docking method, lipid–PON1 interactions were characterized. An inverse correlation was obtained between the lactonase activity of PON1 and the docking energy of the lipid–PON1 complex. Furthermore, five of the lipids increased the LDL oxidation lag time and inhibited its propagation. Our findings suggest a beneficial effect of lyso-DGTS or lyso-DGTS derivatives through increased PON1 activity and prevention of LDL oxidation.

Overweight and obesity in polycystic ovary syndrome: association with inflammation, oxidative stress and dyslipidaemia

Polycystic ovary syndrome (PCOS) is associated with altered lipid profile and increased small, dense LDL particles (sdLDL). Considering that paraoxonase 1 (PON1) is an antioxidative enzyme located on HDL particles, the aim of this study was to investigate the connection between oxidative stress (OS) and PON1 activity with lipoprotein subclasses in PCOS depending on obesity. In 115 PCOS patients, lipoprotein subclasses distributions were determined by gradient gel electrophoresis. OS status was assessed by total oxidative status (TOS), advanced oxidation protein products, malondialdehyde (MDA), prooxidant-antioxidant balance (PAB), total antioxidative status (TAS) and superoxide dismutase (SOD) and PON1 activity. Overweight/obese PCOS patients (n 55) had increased OS compared with normal weight patients (n 60). In addition, overweight/obese group had lower HDL size and higher proportion of HDL 3a subclasses (P < 0·05). PAB was in negative correlation with HDL 2a (P < 0·001), whereas MDA and SOD correlated positively with HDL 3 subclasses (P < 0·05). Serum PON1 activity was positively associated with proportions of PON1 activity on HDL 2b (P < 0·05) and 2a (P < 0·01), but negatively with the proportion on HDL 3 particles (P < 0·01). LDL B phenotype patients had increased TAS, SOD and PON1 activity on HDL 2b, but decreased PON1 activity on HDL 3 subclasses. OS is associated with altered lipoprotein subclasses distribution in PCOS patients. Obesity in PCOS affects the profile of HDL subclasses, reflected through the reduced proportion of PON1 activity on HDL 3 subclasses in the presence of sdLDL particles.

PON1 (Paraoxonase 1) Q192R gene polymorphism in ischemic stroke among North Indian population

Background:

PON1 is an High Density Lipoprotein (HDL)-associated esterase. Two common polymorphisms in the PON1 gene, Q192R and L55M substitutions, determine the inter-individual variation in PON1 activity. The association of these polymorphisms with the risk of ischemic stroke remains controversial. In the present study, the role of PON1 Q192R gene polymorphism in ischemic stroke was studied in the Indian population.

Design and Methods:

In the present case-control study, the PON1 Q192R gene polymorphism was screened in ischemic stroke patients (n: 63) and age, sex-matched controls (n: 63) using thePolymerase Chain Reaction-Restriction Segment Length Polymorphism (PCR-RFLP) method.

Results:

The mean age of stroke presentation was 58.11 ± 15.4 years. A total of 17.4% cases presented with young stroke (<45 years age) and 9.52% cases were seen to have a recurrent stroke. The distribution of -192Q/R PON1 gene polymorphism was not seen to differ between cases and controls. The traditional stroke risk factors did not have any effect on the PON1 genotype expression. A multivariate logistic regression analysis was done in order to assess an independent association of age, gender, traditional stroke risk factors, and PON1 polymorphism with acute ischemic stroke. However, neither the RR genotype nor the presence of the R allele was associated with an increase in the risk of acute ischemic stroke (OR [RR genotype]-4.76, P value: 0.24, 95% CI: 0.3497–64.8531; OR [R allele]-0.94, P value: 0.90, 95% CI: 0.3516–2.4989).

Conclusion:

PON1 Q192R gene polymorphism is not associated with an increased risk of acute ischemic stroke in the North Indian population. Further studies with a larger sample size are needed before PON1 Q192R gene polymorphism can be considered as a genetic risk factor for ischemic stroke.

Antioxidant status in hypertensive disorders of pregnancy

Objective: Pregnancy can be associated with maternal hypertension leading to possible complications in pregnancy outcome. Antioxidant status may be proned to changes during pregnancy with hypertension. The aim of our study was to estimate antioxidant status through high-risk pregnancies.Methods: Seventy-nine pregnant women with high-risk for preeclampsia development were included and 46 of them developed some hypertensive disorder in pregnancy. Superoxide-dismutase (SOD) and paraoxonase 1 (PON1) activities and relative proportion of PON1 activiity on different HDL subclasses were determined in 1^st, 2^nd, and 3^rd trimester and prior to delivery.Results: SOD activity was significantly lower in 2^nd and 3^rd trimesters when compared to 1^st trimester (P˂0.001) whereas PON1 activity was significantly higher in 3^rd than in 1^st trimester (P˂0.05) in group of hypertensive women. This group had significantly higher SOD and PON1 activities and relative proportion of PON1 on HDL_3c subclasses in the 1^st trimester, significantly increased PON1 in the 3^rd trimester and prior to delivery and significantly higher PON1 activity on HDL_3c subclasses (P˂0.05) than nonhypertensive group. In 1^st trimester and prior to delivery, total PON1 activity and relative proportion of PON1 on HDL_3c subclasses exhibited significant ability to mark out hypertension in pregnancy (P˂0.05).Conclusions: SOD activity decreased whereas total PON1 activity increased during pregnancy with hypertension. Pregnant women with hypertension had higher activities of PON1 and SOD and relative proportion of PON1 on HDL_3c subclasses than nonhypertensive ones. PON1 activity and relative proportion of PON1 on HDL_3c subclasses exhibited significant association with hypertension in pregnancy.

Evaluation of dysfunctional high-density lipoprotein levels with myeloperoxidase/paraoxonase-1 ratio in rheumatoid arthritis

BACKGROUND

The aim of this study is to evaluate dysfunctional high-density lipoprotein cholesterol (HDL) by measuring myeloperoxidase (MPO)/paraoxonase 1 (PON1) ratio in patients with rheumatoid arthritis (RA) and to investigate the relationship between dysfunctional HDL and cardiovascular disease (CVD) in RA patients.

METHODS

Sixty-seven healthy individuals and 130 RA patients were included in the study. Routine lipid panels (triglyceride (TG), low-density lipoprotein cholesterol (LDL), HDL, total cholesterol (TC), PON1 and MPO levels were measured. Disease activity scores-28 (DAS28) of RA patients were calculated. Cardiological examination records of the patients were assessed to detect patients who also have CVD.

RESULTS

There were no significant differences between RA and control groups in routine lipid profiles (P > .05 for all). MPO/PON1 ratios were significantly elevated in the RA group compared with the control group (P < .001). MPO/PON1 ratios were higher in RA patients with CVD history compared with those without CVD (P < .05). MPO/PON1 ratios were correlated with DAS28 scores (rho: 0.357, P < .001).

CONCLUSION

HDL dysfunction determined by the MPO/PON1 ratio may be associated with the pathophysiology of increased CVD in RA. Thus, evaluating dysfunctional HDL levels by measuring the MPO/PON1 ratio in RA patients may allow more detailed patient follow-up, as well as the reduction of CVD events in RA patients with therapeutic agents aiming to increase the functional properties of HDL by decreasing this ratio.

Fisetin Alleviates Neointimal Hyperplasia via PPARγ/PON2 Antioxidative Pathway in SHR Rat Artery Injury Model

The phenotypic transformation of proliferation and migration in vascular smooth muscle cells (VSMCs) from media to intima is the basic pathology of neointimal hyperplasia after angioplasty in hypertensive patients. Angiotensin II (AngII) stimulates oxidative stress in VSMC, inducing VSMC proliferation and migration, which is a critical factor in both developments of hypertension and angioplasty-induced arterial restenosis. Fisetin, a plant flavonoid polyphenol, has been reported to be antioxidative and potent senolytic. It is unknown whether fisetin would inhibit neointimal hyperplasia. Therefore, we investigated the role of fisetin in neointimal formation in vitro and in vivo. The rat thoracic aortic smooth muscle cells (A10 cells) stimulated by AngII were used as the in vitro neointimal hyperplasia model, where AngII significantly induced the proliferation and migration in A10 cells. We found that fisetin could dose-dependently inhibit the effect of AngII via inducing the expression of an antioxidant, paraoxonase-2 (PON2), whose overexpression could inhibit the proliferation and migration of A10 cells and downexpression by siRNA had the opposite effect. Furthermore, we found the mechanism of fisetin's inducing PON2 expression involved PPARγ. Rosiglitazone, a PPARγ agonist, could increase PON2 expression in A10 cells, while the PPARγ inhibitor prevented the effect of fisetin on PON2. The in vivo neointimal hyperplasia model was established 2 weeks after the carotid artery balloon injury in SHR rats. Administration of fisetin (ip 3 mg/kg daily for 2 weeks) right after the injury significantly increased PON2 expression in the artery, inhibiting ROS production, and efficiently reduced carotid neointimal hyperplasia. These results indicate that fisetin increases the expression of antioxidant PON2 via activation of PPARγ, reducing oxidative stress, inhibiting VSMC proliferation and migration, and alleviates neointimal hyperplasia after intimal injury. PON2 may be a potential therapeutic target to reduce arterial remodeling after angioplasty in hypertensive patients.

Lactonase activity and status of paraoxonase 1 and oxidative stress in neonates of women with gestational diabetes mellitus

BACKGROUND

The level and lactonase activity of paraoxonase 1 (PON1) and their association with PON1 genetic variants and oxidative stress are unclear in neonates of women with gestational diabetes mellitus (GDM).

METHODS

This study included 362 neonates of women with GDM and 302 control neonates. The level, lactonase activity, normalized lactonase activity (NLA), and genetic polymorphisms of PON1, serum total oxidant status (TOS), total antioxidant capacity (TAC), and malondialdehyde (MDA) were analyzed.

RESULTS

The neonates of the women with GDM had significantly higher levels, lactonase activity, and NLA of PON1, higher TOS, TAC, and MDA concentrations, and relatively higher oxidative stress index than those of the control neonates. The PON1 -108C → T variation decreased the lactonase activity, level, and NLA of PON1, while the PON1 192Q → R variation decreased the PON1 NLA in a genotype-dependent manner in the two groups. Multivariable regression analysis revealed the PON1 -108C/T or 192Q/R variation, apolipoprotein (apo)A1, or apoB as significant predictors of the level, lactonase activity, and NLA of PON1.

CONCLUSIONS

The lactonase activity, level, and NLA of PON1 were increased in the neonates of women with GDM. The PON1 genetic variants, abnormalities in lipoproteins, and increased oxidative stress may be associated with these changes.

IMPACT

This is the first study to report the elevated level, lactonase activity, and NLA of PON1 in the neonates of women with GDM. These neonates also exhibited increased oxidative stress and an adverse glycolipid metabolic profile. We further established that the -108C/T and/or 192Q/R genetic variants of the PON1 gene, abnormalities in lipoprotein metabolism, and/or increased oxidative stress had noticeable influences on the level and activities of PON1. Whether these changes potentially cause metabolic disorders later in life remains to be determined. Therefore, the neonates born to women with GDM require further clinical follow-ups.

Changes in the Nrf2/Keap1 Ratio and PON1 Concentration in Plasma of Patients Undergoing the Left Main Coronary Artery Stenting

Nuclear factor erythroid 2-related factor2 (Nrf2), together with its inhibitor Kelch-like ECH-associated protein 1 (Keap1), is a crucial regulator of cellular redox response. Nrf2 binds to the antioxidant response element (ARE) present in the DNA sequence of a broad group of antioxidant compounds, including paraoxonase (PON1), inducing their transcription. This study was to answer the question of the effect of temporary ischemia/oxidative stress resulting from the left main stenting via percutaneous coronary intervention (LMPCI) performed in the patients included in this study on the cellular redox balance, which is guarded by the Nrf2/Keap1 interaction. We expected a reflection of the redox imbalance due to reactive oxygen species (ROS) in the change in PON1 concentration observed in the following stages of the study, as well as in total antioxidant capacity (TAC) levels. Our results showed the mobilization of cellular Nrf2/Keap1 team right after the procedure (pre-LMPCI median: 2.532, range: 0.07-11.88; post-LMPCI median: 3.735, range: 0.1545-16.18; 24 h-LMPCI median: 5.596, range: 0.02-49.18), which suggest being the result of oxidative stress that accompanies percutaneous coronary intervention (PCI). The course of Keap1 and Nrf2 concentrations at all stages of the experiment appeared to show that Keap1 shadowed the Nrf2 to switch off its activity after Nrf2 induced the mobilization of the antioxidant response. We observed an increase in PON1 concentration (pre-LMPCI median: 179.3, range: 49.76-6120; post-LMPCI median: 215.7, range: 3.80-2771) and a decrease in the TAC level immediately after PCI (pre-LMPC: $1.008\pm 0.27\text{I}$ , post-LMPCI: $0.8030\pm 0.27$ ). This study design allowed for the first time to analyze the chronology of mechanisms and the relationship between selected parameters reflecting the redox state in patients’ plasma. We may conclude that ischemia induced by the PCI was the source of imbalance in the Nrf2/Keap1 ratio via oxidative stress, and this leads to an increase in PON1 concentration first and, in the next step, the TAC mobilization.

Influence of Human Paraoxonase-1 Polymorphism (Q192R) on Serum Levels of Clinical Biomarkers Indicatives of Cardiovascular Diseases Risk in Mexican Women

Human paraoxonase-1 (PON1) is a hydrolytic enzyme related in the onset, establishment, and progression of inflammatory illnesses, including cardiovascular diseases (CVD). Therefore, the primary goal of this investigation was to determinate the influence of the PON1 gene polymorphism (Q192R) on prognostic biomarkers of CVD in women (n = 350) from San Luis Potosi, Mexico. For everyone enrolled, anthropometric, clinical, and biochemical measurements were acquired. Q192R polymorphism of the PON1 gene was assessed by real-time PCR using TaqMan probes. Also, quantification and/or calculation of suggested predictive CVD biomarkers were completed. The association between PON1(Q192R) polymorphism with clinical predictive CVD biomarkers was assessed using univariate and multivariate logistic regression models. Genotype PON1 (Q192R) frequencies were: 18%, 47% and 35% for QQ, QR, and RR, respectively. Besides, the frequency of the variant R allele was 0.58. Furthermore, robust significant associations were found between PON1 (Q192R) polymorphism with serum ADMA [OR (95% CI); 3.50 (1.20-5.00), p < 0.01]; FABP4 [2.50 (2.15-3.95), p < 0.01]; and miR-126 [1.50 (1.15-2.00), p < 0.01] levels after adjusting for probable confounders. Data found in this research strongly support the notion that proposes a crucial role of PON1 enzyme (Q192R polymorphism) as a genetic determinant in the CVD risk in Mexican women.

Leisure time physical activity is associated with improved HDL functionality in high cardiovascular risk individuals: a cohort study

AIMS

Physical activity has consistently been shown to improve cardiovascular health and high-density lipoprotein-cholesterol levels. However, only small and heterogeneous studies have investigated the effect of exercise on high-density lipoprotein functions. Our aim is to evaluate, in the largest observational study to date, the association between leisure time physical activity and a range of high-density lipoprotein functional traits.

METHODS

The study sample consisted of 296 Spanish adults at high cardiovascular risk. Usual leisure time physical activity and eight measures of high-density lipoprotein functionality were averaged over two measurements, one year apart. Multivariable linear regression models were used to explore the association between leisure time physical activity (exposure) and each high-density lipoprotein functional trait (outcome), adjusted for cardiovascular risk factors.

RESULTS

Higher levels of leisure time physical activity were positively and linearly associated with average levels over one year of plasma high-density lipoprotein-cholesterol and apolipoprotein A-I, paraoxonase-1 antioxidant activity, high-density lipoprotein capacity to esterify cholesterol and cholesterol efflux capacity in individuals free of type 2 diabetes only. The increased cholesterol esterification index with increasing leisure time physical activity reached a plateau at around 300 metabolic equivalents.min/day. In individuals with diabetes, the relationship with cholesteryl ester transfer protein followed a U-shape, with a decreased cholesteryl ester transfer protein activity from 0 to 300 metabolic equivalents.min/day, but increasing from there onwards. Increasing levels of leisure time physical activity were associated with poorer high-density lipoprotein vasodilatory capacity.

CONCLUSIONS

In a high cardiovascular risk population, leisure time physical activity was associated not only with greater circulating levels of high-density lipoprotein-cholesterol, but also with better markers of high-density lipoprotein functionality, namely cholesterol efflux capacity, the capacity of high-density lipoprotein to esterify cholesterol and paraoxonase-1 antioxidant activity in individuals free of diabetes and lower cholesteryl ester transfer protein activity in individuals with type 2 diabetes.

Paraoxonase-1: Characteristics and Role in Atherosclerosis and Carotid Artery Disease

Paraoxonase-1 (PON-1) is a calcium-dependent enzyme that is synthesized in the liver and then secreted in blood where it is bound to high density lipoprotein (HDL). PON-1 is a hydrolase with a wide range of substrates, including lipid peroxides. It is considered responsible for many of the antiatherogenic properties of HDL. PON-1 prevents low density lipoprotein (LDL) oxidation, a process that is considered to contribute to the initiation and development of atherosclerosis. PON-1 activity and levels are influenced by gene polymorphisms; of the 2 common variants, one is in position 192 (Q192R) and one in position 55 (M55L). Also, many drugs affect PON-1 activity. The role of PON-1 in carotid atherosclerosis is inconsistent. Some studies show an association of PON-1 polymorphisms with carotid plaque formation, whereas others do not. The aim of this review is to summarize the characteristics of PON-1, its interactions with drugs and its role in atherosclerosis and especially its relationship with carotid artery disease.

High Concentration of Medium-Sized HDL Particles and Enrichment in HDL Paraoxonase 1 Associate With Protection From Vascular Complications in People With Long-standing Type 1 Diabetes

OBJECTIVE

A subset of people with long-standing type 1 diabetes (T1D) appears to be protected from microvascular and macrovascular complications. Previous studies have focused on improved abilities to respond to glucose and its downstream effects as protective mechanisms. It is unclear whether lipoproteins play a role in the vascular health of these people. We therefore determined whether HDL particle concentration, size, function, and/or protein composition associate with protection from vascular complications.

RESEARCH DESIGN AND METHODS

We studied two independent cross-sectional cohorts with T1D: the T1D Exchange Living Biobank (n = 47) and the Joslin Medalist Study (n = 100). Some of the subjects had vascular complications, whereas others never exhibited vascular complications, despite an average duration of diabetes in the cohorts of 45 years. We assessed HDL particle size and concentration by calibrated ion mobility analysis, the HDL proteome by targeted mass spectrometry, and HDL function ex vivo by quantifying cholesterol efflux capacity and inhibition of monocyte adhesion to endothelial cells.

RESULTS

In both cohorts, people without vascular complications exhibited significantly higher concentrations of medium-sized HDL particles (M-HDL) independently of total and HDL cholesterol levels. While no consistent differences in HDL functions were observed ex vivo, people without vascular complications had higher levels of HDL-associated paraoxonase 1 (PON1), an enzyme that inhibits atherosclerosis in animal models.

CONCLUSIONS

Elevated concentrations of M-HDL particles and elevated levels of HDL-associated PON1 may contribute to long-term protection from the vascular complications of diabetes by pathways that are independent of total cholesterol and HDL cholesterol.

Paraoxonase-1 and Symptomatic Status in Carotid Artery Disease

BACKGROUND

Paraoxonase-1 (PON-1) is a high-density lipoprotein (HDL)-associated hydrolase that appears to have a protective action against atherosclerosis. The aim of our study is to identify whether PON-1 levels may be associated with the manifestation of symptoms in patients with carotid artery stenosis.

METHODS

We studied all patients who underwent carotid endarterectomy in the Vascular Surgery Department of Laikon Hospital, Athens, Greece, from July 2012 to July 2014. Medical history was recorded and PON-1 glucose, total cholesterol, HDL cholesterol, low-density lipoprotein cholesterol, and triglycerides levels were measured. Variables were compared between symptomatic and asymptomatic patients. A receiver operating characteristic (ROC) curve was constructed to evaluate the accuracy of PON-1 to predict symptoms.

RESULTS

A total of 74 patients were included, 41 were asymptomatic and the mean age was 68.5 years. The 2 groups appear to differ significantly with regards to the PON-1 levels, with the symptomatic group showing lower levels (5.3 ± 1.19 vs. 4.6 ± 1.36 ng/mL; P = 0.025). ROC analysis demonstrated an area under the curve of 0.654 (P = 0.023).

CONCLUSIONS

Reduced PON-1 levels showed a significant association with symptomatic status, which was independent of other traditional cardiovascular factors. Further studies are required to prospectively assess the role of PON-1 in predicting cerebrovascular events in patients with carotid artery disease.

Assessment of PON1 activity and circulating TF levels in relation to BMI, testosterone, HOMA-IR, HDL-C, LDL-C, CHO, SOD activity and TAC in women with PCOS: An observational study

BACKGROUND

Polycystic Ovary Syndrome (PCOS) is the most common female endocrinopathy among premenopausal women associated with hyperandrogenism, obesity, dyslipidemia, insulin resistance and inflammation. Oxidative stress is an important component of cardio-metabolic risk seen in PCOS.

MATERIAL AND METHODS

A total of 95 women with PCOS and 95 healthy controls were included in this observational study. Serum PON1 activity and stress markers were measured by spectrophotometric methods. Circulating TF level was measured by ELISA.

RESULTS

We found decreased PON1 activity and increased TF levels in women with PCOS compared to healthy controls. Fasting insulin, HOMA-IR, testosterone, LDL-C, MDA, PC and SOD activity were significantly increased whereas FGIR, QUICKI, HDLC, CAT and TAC were significantly decreased in PCOS women than controls. We observed a positive association of PON1 activity with FGIR, QUICKI, HDL-C and TAC, and its negative association was observed with LH, testosterone, fasting insulin and HOMA-IR in PCOS women. We further observed a positive association of TF with waist, waist to hip ratio, BMI, glucose 1hr, cholesterol, LDL-C, SGPT, uric acid and SOD activity in PCOS women.

CONCLUSIONS

Decreased PON1 activity and raised circulating TF levels are respective indicators of pro-inflammatory and procoagulant status in PCOS women. The imbalanced oxidant/antioxidant status further supports the evidences that PCOS is an oxidant state. Further, the association of PON1 activity and TF levels with the clinical, laboratory findings and stress marker levels suggest that these factors taken together are involved in aggravating the pro-inflammatory status in PCOS women.

Expression levels of paraoxonase-1 in aortic valve tissue are associated with the progression of calcific aortic valve stenosis

Background

Paraoxonase-1 (PON1) participates in several vital steps of lipid metabolism, which is associated with calcific aortic valve stenosis (CAVS). Although a few studies have suggested that PON1 in blood could inhibit aortic valve calcification, they did not provide detailed descriptions. In this study, we hypothesized that PON1 is expressed in the aortic valve and that the PON1 level is related to the severity of CAVS.

Methods

A total of 118 consecutive patients with CAVS were enrolled in the study; 35 individuals without aortic valve calcification were included in the control group. Aortic valve tissue was obtained from postoperative pathologic specimens. PON1 was detected qualitatively using immunohistochemistry and quantitatively using an enzyme-linked immunosorbent assay. The severity of aortic stenosis was evaluated using echocardiography.

Results

We detected PON1 in the aortic valve and noticed that the PON1 level was significantly lower in the case group than in the control group (P<0.001). Furthermore, we found no significant difference between the mild and moderate stenosis groups (P=0.395). However, the PON1 levels were obviously higher in both the mild and moderate stenosis groups than in the severe stenosis group (both P<0.001). We also detected a significant negative correlation between PON1 level and the maximum aortic valve gradient in the case group.

Conclusions

We detected PON1 in the aortic valve for the first time, and our results suggest that the PON1 level in aortic valve tissue decreases with increasing severity of aortic valve stenosis.

Paraoxonase 1 in bovine milk and blood as marker of subclinical mastitis caused by Staphylococcus aureus

The aim of this study was to determine serum lipid values and parameters of oxidative stress in blood and milk of cows with subclinical mastitis (SCM) caused by Staphylococcus aureus and to establish association between these parameters. The study was performed on total of 104 cows assigned into control group of healthy animals (n = 12) and two groups of cows with SCM, either SCM₁ group (n = 37) with ˂ 1000 CFU/mL of S. aureus or SCM₂ group (n = 55) with ≥1000 CFU/mL of causative agent in milk. Significantly lower serum concentrations of high density lipoprotein-cholesterol (HDLC) in SCM₂ group and higher low density lipoprotein-cholesterol (LDL-C) in both SCM groups were recorded. Significantly lower paraoxonase-1 (PON1) activity and higher lipid hydroperoxides (LOOH) concentration in blood and milk were recorded in both groups of SCM cows vs control. In blood serum of cows from SCM₂ group significantly higher concentrations of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), but significantly lower total antioxidative capacity (TAC) were obtained. In milk serum of SCM cows were detected significantly higher concentrations of H₂O₂ and MDA, but significantly lower TAC vs control. There was a significant positive correlation between PON1 in serum with HDLC, but negative correlation with LDL-C and LOOH. In milk, PON1 negatively correlated with LOOH and somatic cell counts (SCC). Strong positive correlation was obtained between PON1 in blood and milk. Oxidative stress and inflammatory reaction induced by SCM significantly lowered PON1 activity in blood and milk of affected cows.

Hepatic Forkhead Box Protein A3 Regulates ApoA-I (Apolipoprotein A-I) Expression, Cholesterol Efflux, and Atherogenesis

OBJECTIVE

To determine the role of hepatic FOXA3 (forkhead box A3) in lipid metabolism and atherosclerosis. Approach and Results: Hepatic FOXA3 expression was reduced in diabetic or high fat diet-fed mice or patients with nonalcoholic steatohepatitis. We then used adenoviruses to overexpress or knock down hepatic FOXA3 expression. Overexpression of FOXA3 in the liver increased hepatic ApoA-I (apolipoprotein A-I) expression, plasma HDL-C (high-density lipoprotein cholesterol) level, macrophage cholesterol efflux, and macrophage reverse cholesterol transport. In contrast, knockdown of hepatic FOXA3 expression had opposite effects. We further showed that FOXA3 directly bound to the promoter of the Apoa1 gene to regulate its transcription. Finally, AAV8 (adeno-associated virus serotype 8)-mediated overexpression of human FOXA3 in the hepatocytes of Apoe^-/- (apolipoprotein E-deficient) mice raised plasma HDL-C levels and significantly reduced atherosclerotic lesions.

CONCLUSIONS

Hepatocyte FOXA3 protects against atherosclerosis by inducing ApoA-I and macrophage reverse cholesterol transport.

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.

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

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

Identification of biologically active δ-lactone eicosanoids as paraoxonase substrates

The mammalian paraoxonases (PONs 1, 2 and 3) are a family of esterases that are highly conserved within and between species. They exhibit antioxidant and anti-inflammatory activities. However, their physiological function(s) and native substrates are uncertain. Previous structure-activity relationship studies demonstrate that PONs have a high specificity for lipophilic lactones, suggesting that such compounds may be representative of native substrates. This report describes the ability of PONs to hydrolyze two bioactive δ-lactones derived from arachidonic acid, 5,6-dihydroxy-eicosatrienoic acid lactone (5,6-DHTL) and cyclo-epoxycyclopentenone (cyclo-EC). Both lactones were very efficiently hydrolyzed by purified PON3. PON1 efficiently hydrolyzed 5,6-DHTL, but with a specific activity about 15-fold lower than PON3. 5,6-DHTL was a poor substrate for PON2. Cyclo-EC was a poor substrate for PON1 and not hydrolyzed by PON2. Studies with the PON inhibitor EDTA and a serine esterase inhibitor indicated that the PONs are the main contributors to hydrolysis of the lactones in human and mouse liver homogenates. Studies with homogenates from PON3 knockout mouse livers indicated that >80% of the 5,6-DHTL and cyclo-EC lactonase activities were attributed to PON3. The findings provide further insight into the structural requirements for PONs substrates and support the hypothesis that PONs, particularly PON1 and PON3, evolved to hydrolyze and regulate a class of lactone lipid mediators derived from polyunsaturated fatty acids.

Arylesterase activity of Paraoxonase 1 - prognostic factor for one-year survival in patients with acute myocardial infarction

Introduction: Reduced serum levels of paraoxonase 1 (PON1) activities are associated with diseases involving increased oxidative stress, such as acute coronary syndrome. We aimed to determine whether serum PON1 activities are a prognostic factor for one-year survival following ST-elevation myocardial infarction (STEMI).

Material and methods: We prospectively followed for one-year 75 patients diagnosed and treated for STEMI. Clinical, laboratory and imagistic data were gathered after coronary angiography. PON1 activities (paraoxonase, arylesterase, and lactonase) were assayed spectophotometrically on samples of heparinized plasma taken from the patients in a timeframe of maximum 20 minutes after coronary angiography.

Results: Increased mortality was linked to age (patients over 68 years), permanent atrial fibrillation or left ventricular ejection fraction (LVEF) <40% (associated with global hypokinesia, apical or septal akinesia), trivascular disease atherosclerosis, reduced PON1 activities (paraoxonase <18.4 IU/mL, arylesterase <12.6 IU/mL, lactonase <27.6 IU/mL), and glomerular filtration rate levels <54 mL/min/1.73m2. Multivariate survival analysis showed the independent prognostic role of age (HR 3.92; 95%CI 1.08-14.16; p=0.03), LVEF (HR 9.93; 95%CI 2.20-44.86; p=0.003) and arylesterase (HR 4.25; 95%CI 0.94-19.18; p=0.05) for one-year mortality.

Conclusion: Reduced arylesterase activity of PON1 is an independent predictor of one-year survival after acute myocardial infarction.

Carotid Artery Atherosclerosis: A Review on Heritability and Genetics

Carotid atherosclerosis (CAS) is associated with increased cardiovascular risk, and therefore, assessing the genetic versus environmental background of CAS traits is of key importance. Carotid intima-media-thickness and plaque characteristics seem to be moderately heritable, with remarkable differences in both heritability and presence or severity of these traits among ethnicities. Although the considerable role of additive genetic effects is obvious, based on the results so far, there is an important emphasis on non-shared environmental factors as well. We aimed to collect and summarize the papers that investigate twin and family studies assessing the phenotypic variance attributable to genetic associations with CAS. Genes in relation to CAS markers were overviewed with a focus on genetic association studies and genome-wide association studies. Although the role of certain genes is confirmed by studies conducted on large populations and meta-analyses, many of them show conflicting results. A great focus should be on future studies elucidating the exact pathomechanism of these genes in CAS in order to imply them as novel therapeutic targets.

In silico Molecular Docking and ADME Studies of 1,3,4-Thiadiazole Derivatives in Relation to in vitro PON1 Activity

BACKGROUND

Paraoxonase 1 (PON1) is a paraoxonase, arylesterase and lactonase associated with protection of lipoproteins and cell membranes against oxidative modification.

OBJECTIVE

Based on antioxidative properties of PON1 and significance of 1,3,4-thiadiazoles in pharmaceutical chemistry, herein we aimed to evaluate the potentials of 1,3,4-thiadiazole derivatives as PON1 activators.

METHODS

2-[[5-(2,4-Difluoro/dichlorophenylamino)-1,3,4-thiadiazol-2-yl]thio]acetophenone derivatives (1-18) were in vitro evaluated for their activator effects on PON1 which was purified using ammonium sulfate precipitation (60-80%) and DEAE-Sephadex anion exchange chromatography. Molecular docking studies were performed for the detection of affinities of all compounds to the active site of PON1. Moreover, Absorption, Distribution, Metabolism and Excretion (ADME) properties of all compounds were also in silico predicted. In silico molecular docking and ADME studies were carried out according to modules of Schrodinger's Maestro molecular modeling package.

RESULTS

All compounds, particularly compounds 10, 13 and 17, were determined as promising PON1 activators and apart from compound 1, all of them were detected in the active site of PON1. Besides, ADME results indicated that all compounds were potential orally bioavailable drug-like molecules.

CONCLUSION

PON1 activators, compounds 10, 13 and 17 stand out as potential drug candidates for further antioxidant studies and these compounds can be investigated for their therapeutic effects in many disorders such as atherosclerosis, diabetes mellitus, obesity, chronic liver inflammation and many more.

Paraoxonase-1 is a better indicator than HDL of Atherosclerosis - A pilot study in North Indian population

OBJECTIVES

The present study aims to evaluate the levels of HDL and Paraoxonase-1 (PON1) and their correlation in atherosclerotic patients with and without diabetic mellitus (DM) as well as in control subjects in Northern Indian population.

MATERIALS AND METHODS

We analyzed lipid profiles and Serum PON1 levels by automated analyzer and ELISA, respectively. Study subjects (N = 150) were divided in three groups; Group I: Atherosclerotic patients without DM (N = 50), Group II: Atherosclerotic patients with DM (N = 50); Group III: Controls (N = 50).

RESULTS

We found a significantly (p < 0.0001) low levels of HDL-C in Group I (32.2 ± 7.3) and Group II (36.9 ± 11.5) as compared to Group III (41.0 ± 7.1). PON-1 levels were also significantly lower in Group I (60.1 ± 10.5) and Group II (50.0 ± 13.9) when compared to Group III (95.0 ± 12.0). We observed a significant correlation (r = 0.59, p < 0.001) between the levels of PON1 and HDL-C in study subjects.

CONCLUSIONS

The reduced levels of HDL and PON-1 and their significant correlation in CAD patients may be associated with the pathogenesis of this disease. Considering HDL as a dependent variable, Paraoxonase-1 is the most important parameter contributing to the total variation in HDL in CAD.

Serum Albumin Binding and Esterase Activity: Mechanistic Interactions with Organophosphates

The albumin molecule, in contrast to many other plasma proteins, is not covered with a carbohydrate moiety and can bind and transport various molecules of endogenous and exogenous origin. The enzymatic activity of albumin, the existence of which many scientists perceive skeptically, is much less studied. In toxicology, understanding the mechanistic interactions of organophosphates with albumin is a special problem, and its solution could help in the development of new types of antidotes. In the present work, the history of the issue is briefly examined, then our in silico data on the interaction of human serum albumin with soman, as well as comparative in silico data of human and bovine serum albumin activities in relation to paraoxon, are presented. Information is given on the substrate specificity of albumin and we consider the possibility of its affiliation to certain classes in the nomenclature of enzymes.

Alzheimer's Disease and Paraoxonase 1 (PON1) Gene Polymorphisms

BACKGROUND

Some studies have indicated that human paraoxonase 1 (PON1) activity shows a polymorphic distribution. The aim of this study was to determine the distribution of PON1 polymorphism in patients with Alzheimer's disease in Gorgan and compare it with a healthy control group.

METHOD

The study included 100 healthy individuals and 50 patients. Enzyme activity and genetic polymorphism of PON1 were determined.

RESULT

There were significant differences in distribution of genotypes and alleles among patients and control group. The most common genotype was CT in patients and control group, while the most frequent alleles were T and C in patients and controls, respectively. There was a statistically significant variation between serum PON1 activity and -108C> T polymorphism. The highest PON1 enzyme activities in the patients and controls were found in CC, while lower enzyme activities were seen in CT and TT genotypes in both genders and age groups.

CONCLUSION

Onset of Alzheimer's disease may depend on different polymorphisms of the PON1 enzyme. Late or early-onset of Alzheimer's disease may also depend on age and gender distribution, especially for arylesterase enzyme. Further studies on polymorphism of the enzyme are necessary for interpretation of possible polymorphic effects of enzyme on PON1 activity in humans.

Mediterranean Diet Improves High-Density Lipoprotein Function in High-Cardiovascular-Risk Individuals: A Randomized Controlled Trial

BACKGROUND

The biological functions of high-density lipoproteins (HDLs) contribute to explaining the cardioprotective role of the lipoprotein beyond quantitative HDL cholesterol levels. A few small-scale interventions with a single antioxidant have improved some HDL functions. However, to date, no long-term, large-scale, randomized controlled trial has been conducted to assess the effects of an antioxidant-rich dietary pattern (such as a traditional Mediterranean diet [TMD]) on HDL function in humans.

METHODS

This study was performed in a random subsample of volunteers from the PREDIMED Study (Prevención con Dieta Mediterránea; n=296) after a 1-year intervention. We compared the effects of 2 TMDs, one enriched with virgin olive oil (TMD-VOO; n=100) and the other enriched with nuts (TMD-Nuts; n=100), with respect to a low-fat control diet (n=96). We assessed the effects of both TMDs on the role of HDL particles on reverse cholesterol transport (cholesterol efflux capacity, HDL ability to esterify cholesterol, and cholesteryl ester transfer protein activity), HDL antioxidant properties (paraoxonase-1 arylesterase activity and total HDL antioxidant capacity on low-density lipoproteins), and HDL vasodilatory capacity (HDL ability to induce the release of nitric oxide in endothelial cells). We also studied the effects of a TMD on several HDL quality-related characteristics (HDL particle oxidation, resistance against oxidative modification, main lipid and protein composition, and size distribution).

RESULTS

Both TMDs increased cholesterol efflux capacity relative to baseline (P=0.018 and P=0.013 for TMD-VOO and TMD-Nuts, respectively). The TMD-VOO intervention decreased cholesteryl ester transfer protein activity (relative to baseline, P=0.028) and increased HDL ability to esterify cholesterol, paraoxonase-1 arylesterase activity, and HDL vasodilatory capacity (relative to control, P=0.039, P=0.012, and P=0.026, respectively). Adherence to a TMD induced these beneficial changes by improving HDL oxidative status and composition. The 3 diets increased the percentage of large HDL particles (relative to baseline, P<0.001).

CONCLUSIONS

The TMD, especially when enriched with virgin olive oil, improved HDL atheroprotective functions in humans.

CLINICAL TRIAL REGISTRATION

URL: http://www.controlled-trials.com. Unique identifier: ISRCTN35739639.

Colorimetric and electrophoretic evaluation of lipoprotein fractions in healthy neonatal calves: Comparison with results from adult cows and from calves with inflammatory conditions

High density lipoproteins (HDLs) are pivotal in innate immunity and decrease in serum during inflammation. Several studies have been done about lipoprotein changes in transition cows but little is known about their changes in newborn calves. The aim of this study is to provide information about HDLs in newborn calves, by defining the possible age-related changes in healthy calves compared with adults and by assessing the possible differences in calves with inflammation. Lipoprotein electrophoretic separation (reported as percentages) and colorimetric measurement of HDL (HDL-C) were performed on healthy cows and calves in order to identify possible differences in the lipoprotein profile due to the age. Then, age-matched calves with inflammatory conditions were also evaluated. Results showed that in calves HDL% and VLDL% were lower (mean values±SD: 77.6%±8.6% and 2.6%±2.5%, respectively) and LDL% was higher (19.7%±7.4%) than in adults (89.0%±3.9%; 5.2±2.1% and 5.8%±3.1%, respectively). Sick calves revealed a decrease of both HDL% (mean values ± SD: 61.0%±22.1%) and HDL-C (22.8±11.6mg/dL) and an increase of VLDL% (12.1% ±13.1%) compared with controls (77.6%±8.6%; 41.5±11.2mg/dL and 2.6%±2.5%, respectively). Paraoxonase-1 activity, influenced by inflammation and oxidation, was measured, and it appeared correlated with HDL% and HDL-C in sick calves. In conclusion, this study revealed that HDLs concentration in healthy calves is lower than in adults, and further decreases in calves with inflammation, likely due to oxidation.

Roles of Vascular Oxidative Stress and Nitric Oxide in the Pathogenesis of Atherosclerosis

Major reactive oxygen species (ROS)–producing systems in vascular wall include NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase, xanthine oxidase, the mitochondrial electron transport chain, and uncoupled endothelial nitric oxide (NO) synthase. ROS at moderate concentrations have important signaling roles under physiological conditions. Excessive or sustained ROS production, however, when exceeding the available antioxidant defense systems, leads to oxidative stress. Animal studies have provided compelling evidence demonstrating the roles of vascular oxidative stress and NO in atherosclerosis. All established cardiovascular risk factors such as hypercholesterolemia, hypertension, diabetes mellitus, and smoking enhance ROS generation and decrease endothelial NO production. Key molecular events in atherogenesis such as oxidative modification of lipoproteins and phospholipids, endothelial cell activation, and macrophage infiltration/activation are facilitated by vascular oxidative stress and inhibited by endothelial NO. Atherosclerosis develops preferentially in vascular regions with disturbed blood flow (arches, branches, and bifurcations). The fact that these sites are associated with enhanced oxidative stress and reduced endothelial NO production is a further indication for the roles of ROS and NO in atherosclerosis. Therefore, prevention of vascular oxidative stress and improvement of endothelial NO production represent reasonable therapeutic strategies in addition to the treatment of established risk factors (hypercholesterolemia, hypertension, and diabetes mellitus).

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.

An intensive lifestyle intervention reduces circulating oxidised low-density lipoprotein and increases human paraoxonase activity in obese subjects

OBJECTIVE

Obesity has a great impact on cardiovascular morbidity and mortality, the treatment of this pathological state is important given the significant health consequences. Lifestyle and behaviour changes play a significant role in weight management. The purpose of this study was to investigate the impact of an intensive multidisciplinary lifestyle intervention on well-known atherogenic factors in a group of overweight and obese subjects.

METHODS

A total of 44 people with overweight/obesity underwent a lifestyle intervention based on nutritional education, psychological support and a 3-month exercise training program with a frequency of twice a week. Several anthropometric and biochemical parameters were measured before and after the lifestyle intervention.

RESULTS

Lifestyle intervention led to a significant reduction in metabolic profile including body mass index (BMI), waist circumference, systolic and diastolic blood pressure, plasma glucose, and plasma triglycerides. These reductions were also accompanied by a significant increase in maximal oxygen consumption and muscle strength. Furthermore, paraoxonase and lactonase activities and the concentration of Apoliproteins A1 (APO A1) were significantly increased and the serum levels of oxLDL reduced without any changes in the circulating levels of LDL and HDL.

CONCLUSION

In conclusion, our study suggests that an intensive lifestyle intervention in obese subjects promotes a series of beneficial antiatherogenic changes which included increased enzyme activites of paraoxonase and lactonase, concentration of Apoliproteins A1 and decreased circulating levels of oxLDL.

Paraoxonase 1 (Q192R) gene polymorphism, coronary heart disease and the risk of a new acute coronary event

INTRODUCTION

Paraoxonase 1 (PON1) plays a major role in the oxidation of low density lipoprotein and in the prevention of coronary atherogenesis. In this context, coding region polymorphisms of PON1 gene, responsible for the enzyme activity, has become of interest as a marker for atherogenesis.

METHODS

A study and follow-up was conducted on 529 patients with an acute coronary event in order to assess the association between the PON1 Q192R (rs662;A/G) polymorphism, the type of acute coronary syndrome, cardiovascular risk factors (arterial hypertension, diabetes mellitus, dyslipidaemia, and smoking), the extent and severity of coronary atherosclerosis, and the medium-term clinical follow-up.

RESULTS

The QQ genotype was found in 245 (46.3%) patients, with 218 (41.2%) patients showing the QR genotype, and 66 (14.5%) patients had the RR genotype. No significant differences were found between the QQ and QR/RR genotypes as regards the clinical characteristics, the analytical data, and the angiographic variables. Similarly, Kaplan-Meier survival analysis showed no significant differences in presenting with a new acute coronary event (p=0.598), cardiac mortality (p=0.701), stent thrombosis (p=0.508), or stent re-stenosis (p=0.598) between QQ and QR/RR genotypes during the follow-up period (3.3±2.2 years).

CONCLUSIONS

In patients with an acute coronary syndrome, the PON1 Q192R genotypes did not influence the risk of suffering a new acute coronary event during the medium-term follow-up.

Short-term isocaloric fructose restriction lowers apoC-III levels and yields less atherogenic lipoprotein profiles in children with obesity and metabolic syndrome

BACKGROUND AND AIMS

Dietary fructose may play a role in the pathogenesis of metabolic syndrome (MetS). In a recently published study of obese children with MetS, we showed that isocaloric fructose restriction reduced fasting triglyceride (TG) and LDL-cholesterol (LDL-C). In these ancillary analyses, we tested the hypothesis that these effects were also accompanied by improved quantitative and qualitative changes in LDL and HDL subclasses and their apolipoproteins; as well as change in VLDL, particularly apoC-III.

METHODS

Obese children with MetS (n = 37) consumed a diet that matched self-reported macronutrient composition for nine days, with the exception that dietary fructose was reduced from 11.7 ± 4.0% to 3.8 ± 0.5% of daily calories and substituted with glucose (in starch). Participants underwent fasting biochemical analyses on Days 0 and 10. HDL and LDL subclasses were analyzed using the Lipoprint HDL and LDL subfraction analysis systems from Quantimetrix.

RESULTS

Significant reductions in apoB (78 ± 24 vs. 66 ± 24 mg/dl) apoC-III (8.7 ± 3.5 vs. 6.5 ± 2.6 mg/dl) and apoE (4.6 ± 2.3 vs. 3.6 ± 1.1 mg/dl), all p < 0.001) were observed. LDL size increased by 0.87 Å (p = 0.008). Small dense LDL was present in 25% of our cohort and decreased by 68% (p = 0.04). Small HDL decreased by 2.7% (p < 0.001) and large HDL increased by 2.4% (p = 0.04). The TG/HDL-C ratio decreased from 3.1 ± 2.5 to 2.4 ± 1.4 (p = 0.02). These changes in fasting lipid profiles correlated with changes in insulin sensitivity.

CONCLUSIONS

Isocaloric fructose restriction for 9 days improved lipoprotein markers of CVD risk in children with obesity and MetS. The most dramatic reduction was seen for apoC-III, which has been associated with atherogenic hypertriglyceridemia.

Molecular impact of omega 3 fatty acids on lipopolysaccharide-mediated liver damage

BACKGROUND

Growing evidence suggests that omega 3 fatty acid containing lipid emulsions have a beneficial effect on parenteral nutrition associated liver disease (PNALD). However, the cellular and molecular mechanisms responsible for this effect are unclear. In this study, we investigated whether Omegaven™ fish oil emulsion could inhibit lipopolysaccharidase (LPS) mediated liver damage.

METHODS

We examined the effects of Omegaven™ and LPS alone and synergistically on hepatic paraoxonase 1 (PON1), a potent antioxidant protein, ERK1/2 activity, and TLR4 regulation.

RESULTS

LPS did not alter PON1 release from HepG2 cells but did significantly decrease PON1 protein synthesis (44%, P<0.05). Omegaven™ alone had no direct effect on PON1 release. However, it did significantly reverse LPS-mediated decrease in PON1 protein levels (control: 100%; LPS alone: 56+/4%; LPS+Omegaven™: 87+/6%, P<0.05). Furthermore, molecular analysis indicated that Omegaven™ blocked LPS-mediated increase in ERK1/2 activity (35% increase), an important LPS signal transduction pathway. TLR4, the receptor for LPS, was down-regulated in the presence of Omegaven™.

CONCLUSION

Omegaven™ may be beneficial in patients with PNAC because of its ability to reverse LPS-mediated inhibition of antioxidant promoting PON1 expression, and this activity may be in part mediated by the ERK1/2 pathway.

Establishment of combined analytical method to extract the genes of interest from transcriptome data

Techniques for analyzing genome-wide expression profiles, such as the microarray technique and next-generation sequencers, have been developed. While these techniques can provide a lot of information about gene expression, selection of genes of interest is complicated because of excessive gene expression data. Thus, many researchers use statistical methods or fold change as screening tools for finding gene sets whose expression is altered between groups, which may result in the loss of important information. In the present study, we aimed to establish a combined method for selecting genes of interest with a small magnitude of alteration in gene expression by coupling with proteome analysis. We used hypercholesterolemic rats to examine the effects of a crude herbal drug on gene expression and proteome profiles. We could not select genes of interest by using standard methods. However, by coupling with proteome analysis, we found several effects of the crude herbal drug on gene expression. Our results suggest that this method would be useful in selecting gene sets with expressions that do not show a large magnitude of alteration.

•

Herbal crude drug SJG had mild effects on the gene expression profile.

•

It was difficult to select genes altered by SJG with conventional methods.

•

We established analytical method for transcriptome by using proteome experiments.

•

We identified genes of interest that could not be selected by conventional methods.

Hyperlipidemia-induced hepatic and small intestine ER stress and decreased paraoxonase 1 expression and activity is associated with HDL dysfunction in Syrian hamsters

SCOPE

We aimed at investigating the mechanisms linking hyperlipidemia (HL) with dysfunctional HDL and its main antioxidant enzyme, paraoxonase1 (PON1). PON1 expression and activity was determined in the small intestine, liver, and sera of normal and HL hamsters and associated with the ER stress (ERS) and the development of aortic valve lesions.

METHODS AND RESULTS

Male Golden Syrian hamsters were fed standard chow (N) or standard diet with 3% cholesterol and 15% butter for 16 weeks. All hamsters on fat diet developed HL, 50% also hyperglycemia (HLHG) and a fourfold increased homeostasis model assessment of insuline resistance. PON1 expression was reduced in the small intestine and liver (N > HL > HLHG) along with the increased extent of ERS, oxidized lipids, and decreased expression of liver X receptors beta (LXRβ) in the small intestine, peroxisome proliferator-activated receptor-γ (PPARγ) in the liver, and of the glucose transporter 4 in the myocardium. Serum PON1 levels decreased along with the increase of oxidized LDL and lesion areas of the aortic valves (N > HL > HLHG).

CONCLUSION

The fat diet activates the ERS and oxidative stress, decreases LXRβ, PPARγ, and PON1 in the small intestine, liver, and sera of all HL animals, in parallel with the appearance of atherosclerotic lesions in the aortic valves.

[On the Enzymatic Activity of Albumin]

Albumin molecule, unlike molecules of many other plasma proteins, is not covered with carbohydrate shell. It plays a crucial role in maintaining of colloid osmotic pressure of the blood, and is able to bind and transport various endogenous and exogenous molecules. The enzymatic activity of albumin, the existence and the role of which most researchers are still skeptical to accept, is of the main interest to us. In this review, a history of the issue is traced, with particular attention to the esterase activity of albumin. The kinetic and thermodynamic characteristics of the interaction of albumin with some substrates are adduced, and possibility of albumin being attributed to certain groups of Enzyme Nomenclature is considered.

Lactonase activity and status of paraoxonase 1 in Chinese women with polycystic ovarian syndrome

OBJECTIVE

To study the relationship between the lactonase activities and status of paraoxonase 1 (PON1) and its association with the PON1 genetic polymorphisms in women with polycystic ovarian syndrome (PCOS).

DESIGN

A case-control study.

METHODS

A total of 455 PCOS patients and 441 control women were included in this study. The lactonase activities and concentrations of PON1 were assayed using 5-thiobutyl butyrolactone (TBBL) and 7-O-diethylphosphoryl-3-cyano-4-methyl-7-hydroxycoumarin (DEPCyMC) respectively. A normalized lactonase activity (NLA) was estimated based on the ratio of TBBLase:DEPCyMCase activity. The PON1 genotypes, serum malondialdehyde (MDA) levels and total antioxidant capacity were analyzed.

RESULTS

The lactonase activities and levels of PON1 were higher in PCOS patients than in the control women. However, the NLA did not significantly differ between groups. The -108C→T variation of the PON1 gene showed decreased lactonase activities and levels of PON1 in a genotype-dependent manner (CC>CT>TT); the 192Q→R variation of the PON1 gene showed increased PON1 lactonase activities and NLA; and the 55L→M variation of the PON1 gene showed decreased lactonase activities and levels of PON1 but an increased NLA. A multivariable regression analysis showed that the -108C/T, 192Q/R, and 55L/M variations of the PON1 gene, serum apolipoprotein A1, and MDA levels were significant predictors of PON1 lactonase activity, PON1 level, and NLA.

CONCLUSIONS

The serum lactonase activities and concentrations of PON1 are increased in PCOS patients. The increased oxidative stress and the -108C/T, 192Q/R, and 55L/M genetic polymorphisms of PON1 may be associated with these changes.

Low protective PON1 lactonase activity in an Arab population with high rates of coronary heart disease and diabetes

BACKGROUND

Recent studies showing that high density lipoproteins (HDL) can effect plaque regression indicate that recent trial failures do not exclude an atheroprotective role of HDL. Instead, they highlight differences between HDL function and measured HDL-cholesterol (HDL-C). PON1 is one key functional activity of HDL. Urban Palestinians have lower HDL-C and a higher incidence and mortality of coronary heart disease than those of Israelis. We hypothesized that the cardioprotective PON1 lactonase and arylesterase activities and PON1 functional genotype may differ between Palestinians and Israelis.

METHODS

We measured PON1 activities in a cross-sectional population-based study of Palestinian (n=960) and Israeli (n=694) residents in Jerusalem, 1654 participants in all.

RESULTS

Palestinians had high prevalences of obesity and diabetes and low mean concentrations of HDL-cholesterol (0.97 mmol/l in men and 1.19 mmol/l in women). Lactonase and arylesterase activities were lower by 10.8% (p=1.2∗10(-14)) and 2.7% (p<0.0005), respectively, in Palestinians as compared to Israelis. The functional genotype distribution, demonstrated by plotting paraoxonase vs lactonase activities, showed a modest between-group difference (p=0.024), with 12.1% RR in Palestinian Arabs vs 8.4% in Israeli Jews, but no overall difference in allele frequencies. Lactonase correlated inversely with age (Spearman's rho=-.156), weakly with BMI (-.059), positively with HDL-C (.173) and non-HDL-C (.103), but was not associated with triglycerides or fasting glucose. Palestinians showed consistently lower lactonase activity in logistic regression models adjusted for multiple covariates and for functional genotype (odds ratios of 1.81 and 1.98, respectively, for the lower fifth vs the upper 4 fifths of lactonase activity p<0.0001).

CONCLUSION

We showed a lower physiologically-significant lactonase PON1 activity in an Arab population, a finding consistent with the high cardiovascular and diabetes risk of Palestinians.