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ABSTRACT: Date (Phoenix dactylifera L.) fruit soluble phenolics composition and anti-atherogenic properties were examined in nine diverse Israeli grown varieties. Ethanol and acetone extracts of 'Amari', 'Barhi', 'Deglet Noor', 'Deri', 'Hadrawi', 'Hallawi', 'Hayani', 'Medjool' and 'Zahidi' fruit were analyzed for phenolics composition by RP-HPLC, and tested for anti-atherogenicity by measuring their effects on LDL susceptibility to copper ion- and free radical-induced oxidation, and on serum-mediated cholesterol efflux from macrophages. The most frequently detected phenolics were hydroxybenzoates, hydroxycinnamates and flavonols. Significant differences in phenolics composition were established between varieties as well as extraction solvents. All extracts inhibited LDL oxidation, and most extracts also stimulated cholesterol removal from macrophages. Considerable varietal differences were measured in the levels of the bioactivities. Also, acetone extracts exhibited a significantly higher anti-atherogenic potency for most varieties. The presence of soluble ingredients with anti-atherogenic capacities in dates and the possible involvement of phenolics are discussed.
Journal of Agricultural and Food Chemistry 04/2013; · 2.82 Impact Factor
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ABSTRACT: OBJECTIVE: To analyze Paraoxonase1 (PON1) impact on GLUT4 expression, glucose metabolism, and the insulin signaling pathway in skeletal muscle cells. METHODS AND RESULTS: We analyzed the effect of PON1 in high-fat-diet-induced insulin resistance in C57BL/6J and in PON1KO mice. Mice were fed normal diet (ND) or high Fat Diet (HFD) for 8 weeks. PON1 deficiency caused enhanced insulin resistance in both ND and HFD mice. PON1 deficiency was associated with increased oxidative stress (OS), increased p38MAPK activity and attenuated insulin-mediated tyrosine phosphorylation of muscle insulin receptor substrate-1 (IRS-1), with a corresponding increase in serine phosphorylation. These effects resulted in decreased glucose uptake in whole-body level, as reflected by glucose tolerance test (GTT), by insulin tolerance test (ITT) and by cellular glycogen accumulation in the liver and in the muscles. PON1 addition to cultured C2 muscle cells enhanced GLUT4 mRNA expression, in a time and concentration dependent manner, increased GLUT4 protein and cellular glycogen accumulation. These effects were mediated via inhibition of p38MAPK activity, resulting in reduced IRS-1 serine phosphorylation and in enhanced IRS-1 tyrosine phosphorylation. The ability of PON1 to increase myocytes GLUT4 expression was partially inhibited upon blocking PON1 SH group, and completely abolished upon PON1 mutation in HIS115 of its catalytic site. CONCLUSION: PON1 plays a beneficial role in glucose regulation and metabolism and may serve as an important tool in diabetes control.
Atherosclerosis 04/2013; · 3.79 Impact Factor
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ABSTRACT: OBJECTIVES: Paraoxonase 1 (PON1) was suggested to play an anti-inflammatory role. In the present study we questioned whether PON1 has a direct impact on macrophage inflammatory responses, and the possible functional implications of such effects. METHODS AND RESULTS: Ex-vivo studies were performed with bone marrow-derived macrophages (BMDM) harvested from C57BL/6 and human-PON1 transgenic (PON1-Tg) mice, and for the in vitro studies the J774.A1 macrophage-like cell line was used. Pro-inflammatory (M1) activation was induced by LPS and INFγ. The spontaneous and M1-induced TNFα and IL-6 secretion were significantly reduced in BMDM derived from PON1-Tg vs. C57BL/6 mice. In vitro, PON1 dose-dependently attenuated both the spontaneous and M1-induced TNFα and IL-6 secretion, and contributed to the anti-inflammatory activity of HDL. Functionally, PON1 attenuated M1-induced production of reactive oxygen species (ROS), phagocytosis, and necrotic macrophage death. PON1 anti-inflammatory activity was mediated, at least in part, via binding to SR-BI, but was independent of the enzyme catalytic activity or of cholesterol efflux stimulation, and did not involve binding to ABCA1. CONCLUSIONS: The present study demonstrates, for the first time, that PON1 directly suppresses macrophage pro-inflammatory responses. These findings suggest that PON1 decreases sustained pro-inflammatory reactions, which subsequently can attenuate plaque progression.
Atherosclerosis 03/2013; · 3.79 Impact Factor
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ABSTRACT: PURPOSE OF REVIEW: Improving serum levels of HDL and its subfractions, as well as, oxidative/inflammatory properties has become a fundamental aim in today's atherosclerosis research. Efforts to reach this goal are paralleled by achievements in drug development toward decreasing serum LDL levels and oxidative status. RECENT FINDINGS: Paraoxonase1 (PON1) is an HDL-associated enzyme that is deemed responsible for many of the HDL's antiatherogenic and cardioprotective characteristics. PON1 is highly sensitive to variations in its milieu, and endogenous compounds (fatty acids, phospholipids), nutritional ingredients (flavonoids and other antioxidants), and environmental elements (reactive nitrogen and oxygen species, metals, surfactants), significantly affect the enzyme's activities. PON1 was shown to be responsible for some of the HDL antiatherogenic characteristics such as HDL-mediated cholesterol efflux from macrophages, and the inhibition of LDL oxidation. SUMMARY: The present review summarizes the recent literature related to various elements in PON1's milieu that regulate its activities, with an emphasis on its interrelation with components of the human carotid atherosclerotic lesion (plaque) which are in constant contact with circulating HDL-associated PON1.
Current opinion in lipidology 03/2013; · 6.13 Impact Factor
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ABSTRACT: Abstract In the current study, we analyzed free radicals scavenging activity of monocytes-macrophages in the absence or presence of antioxidants such as polyphenols or paraoxonase 1 (PON1). THP-1 human monocytic cell line, murine J774A.1 macrophages, as well as human primary monocytes have the capability to scavenge free radicals, as measured by the DPPH assay. This effect (which could be attributed to the cell's membrane), was cell number and incubation time dependent. Upon incubation of J774A.1 macrophages with acetylated LDL (Ac-LDL), with VLDL, or with the radical generator, AAPH, the cells' lipid peroxides content, and paraoxonase 2 (PON2) activity were significantly increased. While non-treated cells decreased DPPH absorbance by 65%, the Ac-LDL-, VLDL- or AAPH-treated cells, decreased it by only 33%, 30%, or 45%, respectively. We next analyzed the effect of J774A.1 macrophage enrichment with antioxidants, such as polyphenols or PON1 on the cells' free radicals scavenging activity. Non-treated cells decreased DPPH absorbance by 50%, whereas vitamin E-, punicalagin- or PJ-treated cells significantly further decreased it, by 75%. Similarly, in PON1-treated cells DPPH absorbance was further decreased by 63%, in association with 23% increment in PON1 catalytic activity. In cells under oxidative stress [treated with AAPH-, or with oxidized LDL], PON1 activity was decreased by 31% or 40%, as compared to the activity observed in PON1 incubated with non-treated cells. We conclude that monocytes-macrophages possess free radicals scavenging activity, which is decreased under atherogenic conditions, and increased upon cell enrichment with potent antioxidants such as nutritional polyphenols, or PON1.
Free radical research 01/2013; · 2.22 Impact Factor
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ABSTRACT: OBJECTIVE: To assess the anti-atherogenic effects on macrophage cholesterol biosynthesis rate, and on cellular oxidative stress by the combination of simvastatin with a potent polyphenolic antioxidant (punicalagin), or with a phytosterol (β-sitosterol), or with pomegranate juice (POM, that contains both of them). METHODS AND RESULTS: Simvastatin (15 μg/ml) decreased J774A.1 macrophage cholesterol biosynthesis rate by 42% as compared to control cells. The addition to the statin of either punicalagin (15 or 30 μM), or β-sitosterol (50 or 100 μM), increased the inhibitory effect of the statin up to 62% or 57%, respectively. Similarly, the combination of POM and simvastatin, resulted in an inhibitory effect up to 59%. While simvastatin inhibited the rate limiting enzyme HMGCoA-reductase, punicalagin, β-sitosterol or POM inhibited macrophage cholesterol biosynthesis downstream to mevalonate. Simvastatin (15 μg/ml) also modestly decreased macrophage reactive oxygen species (ROS) formation by 11%. In the presence of punicalagin (15 or 30 μM) however, a remarkable further inhibition was noted (by 61% or 79%, respectively). Although β-sitosterol alone showed some pro-oxidant activity, the combination of simvastatin, β-sitosterol and punicalagin, clearly demonstrated a remarkable 73% reduction in ROS production. Similarly, simvastatin + POM decreased the extent of ROS formation by up to 63%. These improved antioxidant effects of the combinations could be related to various anti-oxidative properties of the different compounds, including free radicals scavenging capacity, upregulation of paraoxonase 2, and stimulation of reduced glutathione. CONCLUSION: The combination of simvastatin with potent antioxidant and phytosterol (such as present in pomegranate) could lead to attenuation of macrophage foam cell formation and atherogenesis.
Atherosclerosis 10/2012; · 3.79 Impact Factor
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ABSTRACT: The aim of this study was to analyze the effect and mechanism of action of macrophage triglyceride accumulation on cellular PON2 expression. Incubation of J774A.1 (murine macrophages) with VLDL (0-75 μg protein/mL) significantly and dose-dependently increased cellular triglyceride mass, and reactive oxygen species (ROS) formation, by up to 3.3- or 1.8-fold, respectively. PON2 expression (mRNA, protein, activity) in cells treated with VLDL (50 μg protein/mL) was higher by 2- to 3-fold, as compared with control cells. Similar effects were noted upon using THP-1 (human macrophages). Incubation of macrophages with synthetic triglyceride or triglyceride fraction from carotid lesion resulted in similar effects, as shown for VLDL. Upon using specific inhibitors of MEK1/2 (UO126, 10 μM), p38 (SB203580, 10 μM), or JNK (SP600125, 20 μM), we demonstrated that MEK, as well as JNK, but not p38, are involved in VLDL-induced macrophage PON2 upregulation. VLDL activated JNK (but not ERK), which resulted in c-Jun phosphorylation. This signaling pathway is probably activated by ROS, since the antioxidant reduced glutathione (GSH), significantly decreased VLDL-induced macrophage ROS formation, c-Jun phosphorylation and PON2 overexpression. We conclude that macrophage triglyceride accumulation upregulates PON2 expression via MEK/ JNK/c-Jun pathway, and these effects could be related, at least in part, to cellular triglycerides-induced ROS formation. © 2012 International Union of Biochemistry and Molecular Biology, Inc.
BioFactors 10/2012; · 4.93 Impact Factor
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ABSTRACT: Diabetes mellitus (DM) and hyperglycemia are associated with premature and accelerated atherosclerosis. This is mediated by induction of vascular dysfunction, increased inflammatory burden and increased lipid peroxidation, all leading to enhanced macrophage foam cell formation. In DM, low density lipoprotein (LDL) oxidation by macrophages is increased due to the activation of several pro-oxidant systems, as well as the depletion of antioxidants, such as the paraoxonases (PONs). Paraoxonases protect against atherogenesis, as serum PON1 exerts a protective role against DM development by stimulating insulin secretion from β cells, and its unique antioxidant properties. Oral supplementation of insulin to mice significantly attenuates macrophage foam cell formation, reduces oxidative stress and decreases the atherosclerotic plaque area and. Insulin may directly inhibit lipid peroxidation via inhibition of NADPH oxidase expression. Insulin has additional protective effects against DM-induced macrophage cholesterol accumulation by inhibiting CD36 expression (an oxidized LDL receptor), and by inhibiting HMGCoA reductase expression (the rate limiting enzyme in cholesterol biosynthesis), through inhibition of the formation of active SREBP-1 (the transcription factor that activates HMGCoA reductase). Although insulin is mainly an anti-atherogenic agent, it also has some pro-atherosclerotic effects in insulin resistant individuals including the induction of dyslipidemia, cellular triglycerides accumulation and pro-thrombotic effects. This review's intent is to help clarify the mechanisms underlying the protective anti-atherogenic role of insulin in DM as well as some pro-atherogenic effects. A better understanding of insulin's involvement in the pathogenesis of atherosclerosis in DM could have major therapeutic implications for DM treatment and its consequent cardiovascular complications.
Pharmacology [?] Therapeutics 08/2012; 136(2):175-85. · 8.56 Impact Factor
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ABSTRACT: We analyzed, for the first time, both in vitro and in vivo, the effect of very low density lipoprotein (VLDL), or of pure triglycerides, on high-density lipoprotein (HDL)-associated paraoxonase1 (PON1) catalytic activities. Incubation of serum or HDL from healthy subjects with VLDL (0-330 μg protein/mL) significantly decreased serum PON1 lactonase or arylesterase activities by up to 11% or 24%, and HDL-associated PON1 lactonase or arylesterase activities by up to 32% or 46%, respectively, in a VLDL dose-dependent manner. VLDL (0-660 μg protein/mL) also inhibited recombinant PON1 (rePON1) lactonase or arylesterase activities by up to 20% or 42%, respectively. Similar inhibitory effect was noted upon rePON1 incubation with pure triglyceride emulsion. Bezafibrate therapy to three hypertriglyceridemic patients (400 mg/day, for one month) significantly decreased serum triglyceride concentration by 67%, and increased serum HDL cholesterol levels by 48%. PON1 arylesterase or paraoxonase activities in the patients' HDL fractions after drug therapy were significantly increased by 86-88%, as compared to PON1 activities before treatment. Similarly, HDL-PON1 protein levels significantly increased after bezafibrate therapy. Finally, bezafibrate therapy improved HDL biological activity, as HDL obtained after drug therapy showed increased ability to induce cholesterol efflux from J774A.1 macrophages, by 19%, as compared to HDL derived before therapy. We thus conclude that VLDL triglycerides inhibit PON1 catalytic activities, and bezafibrate therapy significantly improved HDL-PON1 catalytic and biological activities.
BioFactors 06/2012; 38(4):292-9. · 4.93 Impact Factor
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ABSTRACT: Serum paraoxonase 1 (PON1) is an HDL-associated lipolactonase and its association with hypertension is controversial. We studied the possible role of PON1 in blood pressure (BP) regulation, by using PON1 knockout (PON1KO) mice.
Both, systolic and diastolic BPs were lower in PON1KO compared to WT mice. Hypotension detected in PON1KO is probably neither related to nitric oxide/guanylate cyclase-mediated vasodilation nor to angiotensin II or aldosterone-mediated vasoconstriction. Surprisingly, when challenged by high-salt diet, BP was further reduced in PON1KO mice. The later, pointed to a possible involvement of transient receptor potential vanilloid 4 (TRPV4), and indeed, administration of ruthenium red, a TRPV4 blocker, resulted in a sharp rise in BP. The protein levels of TRPV4 in kidneys of PON1KO were not higher than in WT. However, the renal level of 5,6-epoxyeicosatrienoic acid (5,6-EET), a TRPV4 specific agonist, was significantly higher in PON1KO compared with WT mice. 5,6-EET levels were further elevated under high-salt diet or administration of arachidonic acid. Injection of inhibitor of CYP450 epoxygenase resulted in increased BP in PON1KO mice. Injection of recombinant human PON1 resulted in elevation of BP and a concomitant reduction in renal content of 5,6-EET. PON1, in vitro, metabolized 5,6-EET, but not other EETs, to its corresponding diol. Vasodilation, blocked by excess of dietary K(+) but not reversed by depletion of cellular Ca(2+) stores, point to endothelial-derived hyperpolarization-like response.
The present study shows causal, direct relationship between PON1 and blood pressure which is mediated, at least in part, by the regulation of 5,6-EET.
Atherosclerosis 02/2012; 222(1):92-8. · 3.79 Impact Factor
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ABSTRACT: The current paper summarizes the antioxidative and antiatherogenic effects of pomegranate polyphenols on serum lipoproteins and on arterial macrophages (two major components of the atherosclerotic lesion), using both in vitro and in vivo humans and mice models. Pomegranate juice and its by-products substantially reduced macrophage cholesterol and oxidized lipids accumulation, and foam cell formation (the hallmark of early atherogenesis), leading to attenuation of atherosclerosis development, and its consequent cardiovascular events.
Evidence-based Complementary and Alternative Medicine 01/2012; 2012:382763. · 4.77 Impact Factor
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ABSTRACT: Human carotid plaque components interact directly with circulating blood elements and thus they might affect each other. We determined plaque paraoxonase1 (PON1) hydrolytic-catalytic activity and compared plaque and blood levels of lipids, HDL, PON1, and HbA1c, as well as plaque-oxidized lipids in symptomatic and asymptomatic patients. Human carotid plaques were obtained from symptomatic and asymptomatic patients undergoing routine endarterectomy, and the lesions were ground and extracted for PON activity and lipid content determinations. Plaque PONs preserved paraoxonase, arylesterase, and lactonase activities. The PON1-specific inhibitor 2-hydroxyquinoline almost completely inhibited paraoxonase and lactonase activities, while only moderately inhibiting arylesterase activity. Oxysterol and triglyceride levels in plaques from symptomatic and asymptomatic patients did not differ significantly, but plaques from symptomatic patients had significantly higher (135%) linoleic acid hydroperoxide (LA-13OOH) levels. Their serum PON1 activity, cholesterol and triglyceride levels did not differ significantly, but symptomatic patients had significantly lower (28%) serum HDL levels and higher (18%) HbA1c levels. Thus LA-13OOH, a major atherogenic plaque element, showed significant negative correlations with serum PON1 activity and HDL levels, and a positive correlation with the prodiabetic atherogenic HbA1c. Plaque PON1 retains its activity and may decrease plaque atherogenicity by reducing specific oxidized lipids (e.g., LA-13OOH). The inverse correlation between plaque LA-13OOH level and serum HDL level and PON1 activity suggests a role for serum HDL and PON1 in LA-13OOH accumulation.
Journal of lipids. 01/2012; 2012:762560.
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ABSTRACT: Determination of the cellular uptake of macrocyclic iron(III) complexes by a facile method, accompanied by cell viability tests under both basal and induced oxidative stress, demonstrates that protection against intracellular oxidative stress requires reasonably high internalization and favorable anti/prooxidant profiles. Of the four tested complexes, only amphipolar iron(III) corrole met these criteria.
Inorganic Chemistry 12/2011; 51(1):28-30. · 4.60 Impact Factor
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ABSTRACT: The atherosclerotic lesion is characterized by lipid peroxide accumulation. Paraoxonase 1 (PON1) reduces atherosclerotic lesion oxidative stress, whereas urokinase-type plasminogen activator (uPA) increases oxidative stress in atherosclerotic lesions and contributes to the progression and complications of atherosclerosis. We hypothesized that uPA may promote oxidative stress in the arterial wall via modulation of PON1 activity. Because the liver is the main site for PON1 production, in the present study, we tested whether uPA influences PON1 expression in hepatocytes.
HuH7 hepatocytes were incubated in culture with increasing concentrations of uPA. uPA decreased PON1 gene expression and activity in a dose-dependent manner and accordingly suppressed PON1 secretion from hepatocytes. This effect required uPA/uPA receptor interaction. uPA downregulated PON1 gene expression via inactivation of peroxisome proliferator-activated receptor-γ (PPARγ) activity, and this effect was dependent on uPA-mediated mitogen-activated protein kinase kinase activation. Mechanistic studies showed that uPA enhanced mitogen-activated protein kinase kinase-PPARγ interaction, resulting in PPARγ nuclear export to the cytosol.
This study provides the first evidence that uPA interferes with PPARγ transcriptional activity in hepatocytes, resulting in downregulation of PON1 expression and its secretion to the medium. This may explain, at least in part, the prooxidative effect of uPA in the vascular wall.
Arteriosclerosis Thrombosis and Vascular Biology 12/2011; 32(2):449-58. · 6.37 Impact Factor
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ABSTRACT: We analyzed, for the first time, the effects of recombinant PON1 (rePON1) intraperitoneal injection to C₅₇BL/6 mice on their HDL and macrophage antiatherogenic properties. Thioglycolate-treated mice were injected with either saline (Control), or rePON1 (50 μg/mouse), and 20 H post injection, their blood samples and peritoneal macrophages (MPM) were collected. A significant increase in serum and HDL-PON1 arylesterase and lactonase activities was noted. Similarly, a significant increment, by 3.8 and 2.8 fold, in MPM-PON1 arylesterase and lactonase activities, respectively, as compared to the activities in control MPM was observed. The HDL from rePON1-injected mice was resistant to oxidation by copper ions as compared to control HDL. Furthermore, enrichment of the mouse HDL with rePON1 increased its ability to induce cholesterol efflux from J774A.1 macrophage cell line, and to inhibit macrophage-mediated LDL oxidation. In MPM from rePON1-injected mice vs. control MPM, there was a significant reduction in cholesterol mass, by 42%, in association with inhibition in cellular cholesterol biosynthesis rate, by 33%, and with significant stimulation, by 65%, of human HDL-mediated cholesterol efflux from the cells. We conclude that rePON1 injection to mice improved the mice HDL and MPM antiatherogenic properties, and these effects could probably lead to attenuation of atherosclerosis development.
BioFactors 12/2011; 37(6):462-7. · 4.93 Impact Factor
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ABSTRACT: To analyze the direct effects of paraoxonase-1 (PON1) on diabetes development and on β-cell insulin release.
Injection of rePON1 to mice, prior to STZ-induced diabetes, resulted in reduced incidence of diabetes, as well as, in higher serum insulin levels. Incubation of β-cells with PON1 also dose-dependently increased insulin secretion and its cellular content. PON1 increased cell survival under high glucose levels, but not under high STZ concentrations. The addition of the PON1 carrier in the circulation - HDL, to βTC3 cell line, had an additive effect on PON1-induced insulin secretion. PON1 administration to mice or incubation with β-cells was associated with a substantial decreased oxidative stress. Just like PON1, the dietary anti-oxidants, pomegranate juice, punicalagin (major polyphenol in pomegranate) or vitamin E, also increased insulin release from βTC3, but unlike PON1, failed to increase insulin cellular content, suggesting a possible role for PON1 in insulin biosynthesis, separately from PON1 antioxidative effect. Both, PON1 catalytic activity and PON1 association to HDL, were not required for PON1 stimulation of insulin release from β-cells. However, the PON1 free sulfhydryl group was shown to be essential for insulin release by PON1, as blocking the PON1 SH group, abolished PON1 stimulatory effect on insulin secretion.
PON1 is a potent anti-diabetic enzyme that exerts this protection against diabetes through its antioxidative, as well as via its insulin stimulation properties on β-cells.
Atherosclerosis 08/2011; 219(2):510-8. · 3.79 Impact Factor
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ABSTRACT: Pomegranate extract (POMx) consumption has been shown to reduce the incidence and severity of collagen-induced arthritis in mice.
To investigate whether pomegranate consumption affects disease activity in patients with rheumatoid arthritis (RA), in relation to their serum oxidative status.
In this pilot 12 week open-labeled study eight patients with active RA consumed POMx (10 ml/day) for 12 weeks. Patients' joint status and serum oxidative status (lipid peroxidation, total thiols group, paraoxonase 1 activity) were evaluated at baseline and at week 12.
Six patients completed the study. POMx consumption significantly (P < 0.02) reduced the composite Disease Activity Index (DAS28) by 17%, which could be related mostly to a significant (P < 0.005) reduction in the tender joint count (by 62%). These results were associated with a significant (P < 0.02) reduction in serum oxidative status and a moderate but significant (P < 0.02) increase in serum high density lipoprotein-associated paraoxonase 1 (PON1) activity. The addition of POMx to serum from RA patients reduced free radical-induced lipid peroxidation by up to 25%.
The pomegranate consumption reduced DAS28 in RA patients, and this effect could be related to the antioxidative property of pomegranates. Dietary supplementation with pomegranates may be a useful complementary strategy to attenuate clinical symptoms in RA patients.
The Israel Medical Association journal: IMAJ 08/2011; 13(8):474-9. · 1.02 Impact Factor
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ABSTRACT: To analyze paraoxonase 1 (PON1) effect on monocyte-to-macrophage differentiation.
THP-1 monocytic cell-line and mouse peritoneal macrophages (MPM) were studied. Markers for monocytes differentiation included: morphological changes, CD11b and CD36 expression, and cellular oxidative stress. PON1KO MPM were more differentiated than control C57BL/6 MPM. Intraperitoneal injection of recombinant PON1 (rePON1) to C57BL/6 or to PON1KO mice significantly increased serum, MPM, and tissues PON1 activities. These effects were associated with a significant decrease in CD11b in C57BL/6 and PON1KO MPM (by 21% and 35%, respectively), in CD36 (by 35% and 38%, respectively), and in cellular total peroxides content (by 18% and 20%, respectively). rePON1 also significantly inhibited CD11b and CD36 expression, and cellular total peroxides during PMA-induced THP-1 monocytes differentiation, by 68%, 56% and 53%, respectively. Similar effects were observed upon using reconstituted HDL (rHDL) +rePON1, or human HDL +rePON1, in comparison to rHDL or to human HDL, as well as, HDL from C57BL/6 vs. PON1KO mice. Inhibition of monocyte-to-macrophage differentiation was demonstrated also by several dietary antioxidants such as vitamin E, gallic acid, or punicalagin (the major polyphenol in pomegranate). Whereas NADPH oxidase was not involved in PON1 anti-differentiation effect, mitochondrial complex I could be involved, as rotenone (complex I inhibitor) significantly decreased (by 77%) the expression of CD11b during THP-1 differentiation. Finally, blocking PON1 sulfhydryl group with N-ethylmalemide significantly attenuated PON1 inhibitory effect on THP-I monocyte-to-macrophage differentiation.
HDL-associated PON1 inhibits monocyte-to-macrophage differentiation, and this effect could be related to PON1 peroxidase-like activity which involves its free sulfhydryl group.
Atherosclerosis 07/2011; 219(1):49-56. · 3.79 Impact Factor
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ABSTRACT: Human atherosclerotic lesions contain oxidized lipids that facilitate further oxidation of macrophages, LDLs, and oxidative stress (OS)-sensitive markers and inhibit the antiatherogenic enzyme paraoxonase 1 (PON1). Our aim was to isolate and identify the oxidizing agent in a human atherosclerotic lesion lipid extract (LLE) and to explore the mechanisms of oxidation and of PON1's effect on the oxidizing agent. Of the five main fractions separated from the LLE, only fraction 2 (F2) promoted macrophage reactive oxygen species (ROS) production via a mechanism requiring mitochondrial involvement, whereas the NADPH oxidase system was not involved. Incubation of F2 with PON1 abridged the former's peroxide value and reduced its capacity to oxidize OS markers. The active agent was a triglyceride composed of palmitic, oleic, and linoleic acids, with 0.3% of its linoleic moiety in oxidized form. Incubation of either F2 or an identical synthetic triglyceride with PON1 reduced their ability to oxidize macrophages, without affecting cellular accumulation of triglycerides. We conclude that macrophage ROS production by LLE occurs in the presence of a specific triglyceride and requires mitochondrial involvement. Lipid peroxide in the triglyceride can also facilitate lipid autoxidation. Both atherogenic pathways are suppressed by PON1, which acts as an antiatherogenic element.
Free radical biology & medicine 07/2011; 51(1):234-42. · 5.42 Impact Factor
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Michael Aviram
Current opinion in lipidology 06/2011; 22(3):243-4. · 6.13 Impact Factor
