The absence of p53 accelerates atherosclerosis by increasing cell proliferation in vivo

The tumor suppressor protein p53 is an essential molecule in cell proliferation and programmed cell death (apoptosis), and has been postulated to play a principal part in the development of atherosclerosis. We have examined the effect of p53 inactivation on atherogenesis in apoE-knockout mice, an animal model for atherosclerosis. We found that, compared with p53+/+/apoE-/- mice, p53-/-/apoE-/- mice developed considerably accelerated aortic atherosclerosis in the presence of a similar serum cholesterol in response to a high-fat diet. Furthermore, the atherosclerotic lesions in p53-/-/apoE-/- mice had a significant (approximately 280%) increase in cell proliferation rate and an insignificant (approximately 180%) increase in apoptosis compared with those in p53+/+/apoE-/- mice. Our observations indicate that the role of p53 in atherosclerotic lesion development might be associated with its function in cell replication control, and that p53-independent mechanisms can mediate the apoptotic response in atherosclerosis.     

Lecithin:cholesterol acyltransferase deficiency increases atherosclerosis in the low density lipoprotein receptor and apolipoprotein E knockout mice.

The purpose of the present study was to test the hypothesis that lecithin:cholesterol acyltransferase (LCAT) deficiency would accelerate atherosclerosis development in low density lipoprotein (LDL) receptor (LDLr-/-) and apoE (apoE-/-) knockout mice. After 16 weeks of atherogenic diet (0.1% cholesterol, 10% calories from palm oil) consumption, LDLr-/- LCAT-/- double knockout mice, compared with LDLr-/- mice, had similar plasma concentrations of free (FC), esterified (EC), and apoB lipoprotein cholesterol, increased plasma concentrations of phospholipid and triglyceride, decreased HDL cholesterol, and 2-fold more aortic FC (142 +/- 28 versus 61 +/- 20 mg/g protein) and EC (102 +/- 27 versus 61+/- 27 mg/g). ApoE-/- LCAT-/- mice fed the atherogenic diet, compared with apoE-/- mice, had higher concentrations of plasma FC, EC, apoB lipoprotein cholesterol, and phospholipid, and significantly more aortic FC (149 +/- 62 versus 109 +/- 33 mg/g) and EC (101 +/- 23 versus 69 +/- 20 mg/g) than did the apoE-/- mice. LCAT deficiency resulted in a 12-fold increase in the ratio of saturated + monounsaturated to polyunsaturated cholesteryl esters in apoB lipoproteins in LDLr-/- mice and a 3-fold increase in the apoE-/- mice compared with their counterparts with active LCAT. We conclude that LCAT deficiency in LDLr-/- and apoE-/- mice fed an atherogenic diet resulted in increased aortic cholesterol deposition, likely due to a reduction in plasma HDL, an increased saturation of cholesteryl esters in apoB lipoproteins and, in the apoE-/- background, an increased plasma concentration of apoB lipoproteins.     

Acute angiotensin II increases plasma F2-isoprostanes in salt-replete human hypertensives

Angiotensin (Ang) II induces oxidative stress in vitro and in animal models of hypertension. We tested the hypothesis that Ang II increases oxidative stress in human hypertension, as assessed by plasma F2-isoprostane concentrations. Plasma F2-isoprostanes, hemodynamic and endocrine parameters were measured at baseline and following a 55 min infusion of 3 ng/kg/min Ang II in 13 normotensive and 13 hypertensive volunteers ingesting a high- (200 mmol/d) or low- (10 mmol/d) sodium diet. Mean arterial pressure (MAP) and body mass index were higher in hypertensive subjects. Ang II infusion increased MAP (p<.001) and plasma aldosterone concentrations (p<.001) and decreased plasma renin activity (p<.001) and renal plasma flow (p<.001) to a similar extent in both groups. Plasma F2-isoprostane concentrations were similar at baseline. There was no effect of Ang II on F2-isoprostane concentrations during low-salt intake in either group (normotensive 51.7 +/- 7.1 to 53.7 +/- 6.5 pg/ml and hypertensive 52.2 +/- 8.2 to 56.2 +/- 10.0 pg/ml; mean +/- SE). During high-salt intake, Ang II increased F2-isoprostane concentrations in the hypertensive group (52.3 +/- 7.2 to 63.2 +/- 10.4 pg/ml, p=0.010) but not in the normotensive group (54.2 +/- 4.4 to 58.9 +/- 6.6 pg/ml, p=0.83). Acute Ang II infusion increases oxidative stress in vivo in hypertensive humans. The renin-angiotensin system may contribute to oxidative stress in human cardiovascular disease.     

Hypertriglyceridemia in lecithin-cholesterol acyltransferase-deficient mice is associated with hepatic overproduction of triglycerides, increased lipogenesis, and improved glucose tolerance

Lecithin-cholesterol acyltransferase deficiency is frequently associated with hypertriglyceridemia (HTG) in animal models and humans. We investigated the mechanism of HTG in the ldlr-/- x lcat-/- (double knockout (dko)) mice using the ldlr-/- x lcat+/+ (knock-out (ko)) littermates as control. Mean fasting triglyceride (TG) levels in the dko mice were elevated 1.75-fold compared with their controls (p < 0.002). Both the very low density lipoprotein and the low density lipoprotein/intermediate density lipoprotein fractions separated by fast protein liquid chromatography were TG-enriched in the dko mice. In vitro lipolysis assay revealed that the dko mouse very low density lipoprotein (d < 1.019 g/ml) fraction separated by ultracentrifugation was a more efficient substrate for lipolysis by exogenous bovine lipoprotein lipase. Post-heparin lipoprotein lipase activity was reduced by 61% in the dko mice. Hepatic TG production rate, determined after intravenous Triton WR1339 injection, was increased 8-fold in the dko mice. Hepatic mRNA levels of sterol regulatory element binding protein-1 (srebp-1) and its target genes acetyl-CoA carboxylase-1 (acc-1), fatty acid synthase (fas), and stearoyl-CoA desaturase-1 (scd-1) were significantly elevated in the dko mice compared with the ko control. The hepatic mRNA levels of LXRalpha (lxralpha) and its target genes including angiopoietin-like protein 3 (angptl-3) in the dko mice were unchanged. Fasting glucose and insulin levels were reduced by 31 and 42%, respectively in the dko mice, in conjunction with a 49% reduction in hepatic pepck-1 mRNA (p = 0.014). Both the HTG and the improved fasting glucose phenotype seen in the dko mice are at least in part attributable to an up-regulation of the hepatic srebp-1c gene.     

HDL-associated PAF-AH reduces endothelial adhesiveness in apoE-/- mice.

Macrophage infiltration into the subendothelial space at lesion prone sites is the primary event in atherogenesis. Inhibition of macrophage homing might therefore prevent atherosclerosis. Since HDL levels are inversely correlated with cardiovascular risk, their effect on macrophage homing was assessed in apoE-deficient (apoE-/-) mice. Overexpression of human apolipoprotein AI in apoE-/- mice increased HDL levels 3-fold and reduced macrophage accumulation in an established assay of leukocyte homing to aortic root endothelium 3.2-fold (P<0.005). This was due to reduced in vivo betaVLDL oxidation, reduced betaVLDL triggered endothelial cytosolic Ca2+ signaling through PAF-like bioactivity, lower ICAM-1 and VCAM-1 expression, and diminished ex vivo leukocyte adhesion. Adenoviral gene transfer of human PAF-acetylhydrolase (PAF-AH) in apoE-/- mice increased PAF-AH activity 1.5-fold (P<0.001), reduced betaVLDL-induced ex vivo macrophage adhesion 3.5-fold (P<0.01), and reduced in vivo macrophage homing 2.6-fold (P<0.02). These inhibitory effects were observed in the absence of increased HDL cholesterol levels. In conclusion, HDL reduces macrophage homing to endothelium by reducing oxidative stress via its associated PAF-AH activity. This protective mechanism is independent of the function of HDL as cholesterol acceptor. Modulation of lipoprotein oxidation by PAF-AH may prevent leukocyte recruitment to the vessel wall, a key feature in atherogenesis.     

Short-term passive smoking causes endothelial dysfunction via oxidative stress in nonsmokers

Recent studies have shown that passive smoking impairs vascular endothelial function and induces oxidative stress in humans. However, in most of the previous human data regarding tobacco-induced pathophysiology, vascular endothelial dysfunction and oxidative stress have been separately assessed. This study was designed to determine the association between the acute effect of passive smoking on vascular endothelial function and in-vivo oxidative stress status. We studied 30 healthy male Japanese volunteers (32 +/- 7 years) including 15 habitual smokers and 15 nonsmokers. After baseline echocardiographic, hemodynamic recording, and blood sampling, subjects were exposed to passive smoking for 30 min. Endothelium-dependent vasodilation was measured by using % flow-mediated vasodilation (%FMD) of the brachial artery and plasma levels of 8-isoprostane was measured by enzyme immunoassay before and after the passive smoking exposure. Baseline %FMD was lower (4.3% +/- 1.2% vs. 10.9% +/- 3.1%, p < 0.001) and baseline plasma 8-isoprostane level was higher (41.5 +/- 5.8 pg/mL vs. 26.9 +/- 5.4 pg/mL, p < 0.001) in smokers than those in nonsmokers. The %FMD and 8-isoprostane level did not change after passive smoking in smokers. In nonsmokers, however, the %FMD decreased (to 5.0% +/- 1.9%, p < 0.001) and the 8-isoprostane level increased (to 37.8 +/- 9.6 pg/mL, p < 0.001) significantly after 30 min passive smoking exposure, equivalently to the levels of smokers. Sixty corrected samples before and after passive smoking exposure in all patients showed a significant negative correlation between the % FMD and the plasma 8-isoprostane levels (n = 60, r = -0.69, p < 0.001). Even 30 min of passive smoking rapidly impairs vascular endothelial function, which is associated with oxidative stress. Our data provide the pathophysiological insight for the recent epidemiological evidence about the increased risk of coronary heart disease among nonsmokers exposed to passive smoking.     

Deficiency in inducible nitric oxide synthase results in reduced atherosclerosis in apolipoprotein E-deficient mice

Inducible NO synthase (iNOS) present in human atherosclerotic plaques could contribute to the inflammatory process of plaque development. The role of iNOS in atherosclerosis was tested directly by evaluating the development of lesions in atherosclerosis-susceptible apolipoprotein E (apoE)-/- mice that were also deficient in iNOS. ApoE-/- and iNOS-/- mice were cross-bred to produce apoE-/-/iNOS-/- mice and apoE-/-/iNOS+/+ controls. Males and females were placed on a high fat diet at the time of weaning, and atherosclerosis was evaluated at two time points by different methods. The deficiency in iNOS had no effect on plasma cholesterol, triglyceride, or nitrate levels. Morphometric measurement of lesion area in the aortic root at 16 wk showed a 30-50% reduction in apoE-/-/iNOS-/- mice compared with apoE-/-/iNOS+/+ mice. Although the size of the lesions in apoE-/-/iNOS-/- mice was reduced, the lesions maintained a ratio of fibrotic:foam cell-rich:necrotic areas that was similar to controls. Biochemical measurements of aortic cholesterol in additional groups of mice at 22 wk revealed significant 45-70% reductions in both male and female apoE-/-/iNOS-/- mice compared with control mice. The results indicate that iNOS contributes to the size of atherosclerotic lesions in apoE-deficient mice, perhaps through a direct effect at the site of the lesion.     

Ozone-induced increase in exhaled 8-isoprostane in healthy subjects is resistant to inhaled budesonide

The aim of this study was to quantify lung oxidant stress after short-term ozone exposure as reflected by 8-isoprostane concentrations in exhaled breath condensate (EBC) and to investigate the effects of inhaled budesonide on this response. 8-Isoprostane is a prostaglandin-F(2 alpha) isomer that is formed in vivo by free radical-catalyzed peroxidation of arachidonic acid. EBC is a noninvasive method to collect airway secretions. We undertook a double-blind, randomized, placebo-controlled, crossover study with inhaled budesonide (800 microg) or placebo twice daily for 2 weeks prior to ozone exposure (400 parts per billion) for 2 h in nine healthy nonsmokers. Exhaled 8-isoprostane was measured by an enzyme immunoassay. 8-Isoprostane was increased 4 h after ozone exposure compared to pre-exposure values in both placebo (36.9 +/- 3.9 pg/ml, mean +/- SEM, vs. 16.9 +/- 0.7 pg/ml; p <.001) and budesonide groups (33.4 +/- 2.6 pg/ml vs. 15.8 +/- 0.3 pg/ml; p <.001). Pretreatment with budesonide did not affect the increases in 8-isoprostane (mean differences 3.4 pg/ml, 95% CI -8.9 to 15.7, p =.54). Short-term ozone exposure causes acute increase in lung oxidative stress as reflected by exhaled 8-isoprostane. This increase is resistant to pretreatment with a high dose of inhaled budesonide.     

Atheroma development in apolipoprotein E-null mice is not regulated by phosphorylation of p27(Kip1) on threonine 187

Excessive cellular proliferation is thought to contribute to neointimal lesion development during atherosclerosis and restenosis after angioplasty. Inhibition of cyclin-dependent kinase (CDK) activity by p27 inhibits mammalian cell growth. Mounting evidence indicates that p27 negatively regulates neointimal thickening in animal models of restenosis and atherosclerosis, and its expression in human neointimal lesions is consistent with such a protective role. Cell cycle progression is facilitated by cyclinE/CDK2-dependent phosphorylation of p27 on threonine 187 (T187) during late G1. The purpose of this study was to assess whether this phosphorylation event plays a role during atherosclerosis. To this end, we generated apolipoprotein E-null mice with both p27 alleles replaced by a mutated form non-phosphorylatable at T187 (apoE-/-p27T187A mice) and investigated the kinetics of atheroma development in these animals compared to apoE-/- controls with an intact p27 gene. Fat feeding resulted in comparable level of hypercholesterolemia in both groups of mice. Surprisingly, aortic p27 expression was not increased in fat-fed apoE-/-p27T187A mice compared with apoE-/- controls. Moreover, atheroma size, lesion cellularity, proliferation, and apoptotic rates were undistinguishable in both groups of fat-fed mice. Thus, in contrast to previous studies that highlight the importance of p27 phosphorylation at T187 on the control of p27 expression and function in different tissues and pathophysiological scenarios, our findings demonstrate that this phosphorylation event is not implicated in the control of aortic p27 expression and atheroma progression in hypercholesterolemic mice.     

Increased glycosphingolipid levels in serum and aortae of apolipoprotein E gene knockout mice

The apolipoprotein E gene knockout (apoE-/-) mouse develops atherosclerosis that shares many features of human atherosclerosis. Increased levels of glycosphingolipid (GSL) have been reported in human atherosclerotic lesions; however, GSL levels have not been studied in the apoE-/- mouse. Here we used HPLC methods to analyze serum and aortic GSL levels in apoE-/- and C57BL/6J control mice. The concentrations of glucosyl ceramide (GlcCer), lactosyl ceramide (LacCer), GalNAcbeta1-4Galbeta1-4Glc-Cer (GA2), and ceramide trihexoside (CTH) were increased by approximately 7-fold in the apoE-/- mouse serum compared with controls. The major serum ganglioside, N-glycolyl GalNAcbeta1-4[NeuNAcalpha2-3]Galbeta1-4Glc-Cer (N-glycolyl GM2), was increased in concentration by approximately 3-fold. A redistribution of GSLs from HDL to VLDL populations was also observed in the apoE-/- mice. These changes were accompanied by an increase in the levels of GSLs in the aortic sinus and arch of the apoE-/- mice. The spectrum of gangliosides present in the aortic tissues was more complex than that found in the lipoproteins, with the latter represented almost entirely by N-glycolyl GM2 and the former comprised of NeuNAcalpha2-3Galbeta1-4Glc-Cer (GM3), GM2, N-glycolyl GM2, GM1, GD3, and GD1a. In conclusion, neutral GSL and ganglioside levels were increased in the serum and aortae of apoE-/- mice compared with controls, and this was associated with a preferential redistribution of GSL to the proatherogenic lipoprotein populations. The apoE-/- mouse therefore represents a useful model to study the potential role of GSL metabolism in atherogenesis.     

Inhibition of ileal bile acid transport and reduced atherosclerosis in apoE-/- mice by SC-435

Blocking intestinal bile acid absorption by inhibiting the apical sodium codependent bile acid transporter (ASBT) is a target for increasing hepatic bile acid synthesis and reducing plasma LDL cholesterol. SC-435 was identified as a potent inhibitor of ASBT (IC50 = 1.5 nM) in cells transfected with the human ASBT gene. Dietary administration of 3 mg/kg to 30 mg/kg SC-435 to apolipoprotein E-/- (apoE-/-) mice increased fecal bile acid excretion by >2.5-fold. In vivo inhibition of ASBT also resulted in significant increases of hepatic mRNA levels for cholesterol 7alpha-hydroxylase and HMG-CoA reductase. Administration of 10 mg/kg SC-435 for 12 weeks to apoE-/- mice lowered serum total cholesterol by 35% and reduced aortic root lesion area by 65%. Treatment of apoE-/- mice also resulted in decreased expression of ileal bile acid binding protein and hepatic nuclear hormone receptor small heterodimer partner, direct target genes of the farnesoid X receptor (FXR), suggesting a possible role of FXR in SC-435 modulation of cholesterol homeostasis. In dogs, SC-435 treatment reduced serum total cholesterol levels by 相似文献   

Coronary endothelial dysfunction is not rapidly reversible with ascorbic acid

In humans with cardiovascular risk factors, increased vascular production of superoxide anion may contribute to endothelial dysfunction by its reacting with nitric oxide and reducing its biological activity. High concentrations of ascorbic acid scavenge superoxide anion and restore normal endothelium-dependent vasodilation in humans with cardiovascular risk factors. To investigate the contribution of increased superoxide anion to endothelial dysfunction in atherosclerotic coronary arteries, we examined the effect of sequential infusions of ascorbic acid (final concentration 0.1, 1.0, and 10 mmol/L) or placebo on coronary endothelial function in 26 subjects referred for cardiac catheterization to evaluate coronary artery disease. Coronary vasomotor function was evaluated using intracoronary agonist infusion, quantitative angiography, and intracoronary Doppler measurements. At baseline, endothelium-dependent vasodilation of epicardial arteries and coronary microvessels was impaired to an equivalent extent in the ascorbic acid and placebo groups. Sequential ascorbic acid infusions had no effect on the acetylcholine-induced change in coronary artery diameter (-11+/-8, -12+/-10, and -9+/-9%) compared with the effect of placebo (-14+/-13, -16+/-10, and -13+/-9%) infusions (p=0.98). Similarly, the changes in coronary blood flow during acetylcholine infusions were equivalent during ascorbic acid (51+/-44, 67+/-66, and 62+/-52%) and placebo (61+/-104, 55+/-93, and 50+/-69%) infusions (p=0.63). Ascorbic acid also had no effect on the dilator response to intracoronary nitroglycerin (p=0.19). These data argue against an important role for superoxide-mediated "inactivation" of nitric oxide or another rapidly reversible form of oxidative stress as a mechanism of coronary endothelial dysfunction in patients with coronary atherosclerosis.     

Benzo[a]pyrene enhances lipid peroxidation induced DNA damage in aorta of apolipoprotein E knockout mice

The genotoxic compound benzo[a]pyrene (B[a]P) enhances atherosclerotic plaque progression, possibly by inducing oxidative stress and subsequent lipid peroxidation (LPO). Since LPO plays a key role in atherosclerosis, stable LPO derived DNA modifications such as 1,N6-ethenodeoxy-adenosine (epsilondA) and 3,N4-ethenodeoxy-cytidine (epsilondC) may be useful biomarkers for in vivo oxidative stress. In this study, benzo[a]pyrene-diol-epoxide (BPDE)-DNA, epsilondA and epsilondC were determined by 32P-postlabelling in apolipoprotein E knockout (ApoE-KO) mice treated with 5mg/kg B[a]P by gavage. After 4 days, BPDE-DNA adduct levels were higher in aorta (10.8 +/- 1.4 adducts/10(8) nucleotides) than in lung (3.3 +/- 0.7, P < 0.05), which is a known target organ for B[a]P. Levels of epsilondA were higher in aorta of B[a]P-exposed animals than in unexposed controls (8.1 +/- 4.4 vs 3.4 +/- 2.1 adducts per 10(8) parent nucleotides, P < 0.05). On the other hand, epsilondC levels were not affected by B[a]P exposure. Serum low density lipoprotein (LDL) levels were lower in B[a]P-exposed mice than in controls (9.3 +/- 3.7 and 13.3 +/- 4.0mmol/l, respectively), whereas high density lipoprotein (HDL) levels were higher (1.4 +/- 1.6 and 0.4 +/- 0.3mmol/l, respectively). Consequently, a three-fold difference in the LDL/HDL ratio was observed (P = 0.001). epsilondA levels were positively related with plasma HDL concentrations (R = 0.68, P = 0.02), suggesting that the HDL mediated protection of the vessel wall against reactive lipid peroxides was reduced in B[a]P-exposed apoE-KO mice. Our observations show that direct as well as lipid peroxidation induced DNA damage is formed by B[a]P in aorta of apoE-KO mice, which may be involved in atherosclerotic plaque progression. This study further indicates that etheno-DNA adducts are useful biomarkers for in vivo oxidative stress in atherosclerosis.     

Oxidative stress markers are associated to vascular recurrence in non-cardioembolic stroke patients non-treated with statins

ABSTRACT: BACKGROUND: Since atherogenesis is related to oxidative stress, our objective was to study the association of oxidative stress markers with the vascular recurrence in non-cardioembolic stroke. For this purpose, atherosclerotic and oxidative stress markers (ox-LDL, Cu/Zn SOD and 8-OHDG) were evaluated in 477 non-cardioembolic stroke patients on admission (136 were being treated with statins) and patients were followed at 6 and 12 months. RESULTS: Patients who suffered vascular recurrence or vascular-origin death had higher levels of 8-OHDG (40.06+/-24.70vs33.11+/-15.18;p=0.003). We also found associations between vascular recurrence or vascular origin death and Cu/ZnSOD (OR,1.02; 95%CI,1.00-1.03;p=0.0001) and 8-OHDG (OR,1.12;95%CI,1.08-1.16;p<0.0001) in a subgroup of 333 patients that were not in treatment with statins on admission. We also found associations between 8-OHDG and intima media thickness (IMT) (OR,1.13;95%CI,1.09-1.16;p<0.0001), presence of ipsilatieral stenosis[greater than or equal to]50% (OR,1.03;95%CI1.00-1.05;p=0.007) and other atherosclerotic plaque characteristics. CONCLUSIONS: Specific oxidative stress markers were found to be markers of atherosclerosis plaque types and vascular recurrence in non-statins treated patients at admission.     

Paraoxonase (PON1) deficiency is associated with increased macrophage oxidative stress: studies in PON1-knockout mice

Human serum paraoxonase (PON1), an HDL-associated esterase, protects lipoproteins against oxidation, probably by hydrolyzing specific lipid peroxides. As arterial macrophages play a key role in oxidative stress in early atherogenesis, the aim of the present study was to examine the effect of PON1 on macrophage oxidative stress. For this purpose we used mouse arterial and peritoneal macrophages (MPM) that were harvested from two populations of PON1 knockout (KO) mice: one on the genetic background of C57BL/6J (PON1(0)) and the other one on the genetic background of apolipoproteinE KO (PON1(0)/E(0)). Serum and LDL, but not HDL, lipids peroxidation was increased in PON1(0), compared to C57BL/6J mice, by 84% and by 220%, respectively. Increased oxidative stress was shown in peritoneal and in arterial macrophages derived from either PON1(0) or PON1(0)/E(0) mice, compared to their appropriate controls. Macrophage oxidative stress was expressed by increased lipid peroxides content in MPM from PON1(0) and from PON1(0)/E(0) mice by 48% and by 80%, respectively, and by decreased reduced glutathione (GSH) content, compared to the appropriate controls. Furthermore, increased capacity of MPM from PON1(0) and PON1(0)/E(0) mice to oxidize LDL (by 40% and by 19%, respectively) and to release superoxide anions was observed. In accordance with these results, PON1(0) mice MPM exhibited 130% increased translocation of the cytosolic p47phox component of NADPH-oxidase to the macrophage plasma membrane, suggesting increased activation of macrophage NADPH-oxidase in PON1(0) mice, compared to control mice MPM. The increase in oxidative stress in PON1-deficient mice was observed despite the presence of the two other members of the PON gene family. PON2 and PON3 activities and mRNA expression were both found to be present in PON1-deficient mice MPM. Upon incubation of PON1(0)/E(0) derived macrophages with human PON1 (7.5 arylesterase units/ml), cellular peroxides content was decreased by 18%, macrophage superoxide anion release was decreased by 33%, and macrophage-mediated oxidation of LDL was reduced by 22%. Finally, a 42% increase in the atherosclerotic lesion area was observed in PON1(0)/E(0) mice, in comparison to E(0) mice under regular chow diet. We thus concluded that PON1 can directly reduce oxidative stress in macrophages and in serum, and that PON1-deficiency results in increased oxidative stress not only in serum, but also in macrophages, a phenomenon that can contribute to the accelerated atherosclerosis shown in PON1-deficient mice.     

Anti-atherogenic effect of coenzyme Q10 in apolipoprotein E gene knockout mice

Oxidation of low-density lipoprotein (LDL) lipid is implicated in atherogenesis and certain antioxidants inhibit atherosclerosis. Ubiquinol-10 (CoQ10H2) inhibits LDL lipid peroxidation in vitro although it is not known whether such activity occurs in vivo, and, if so, whether this is anti-atherogenic. We therefore tested the effect of ubiquinone-10 (CoQ10) supplemented at 1% (w/w) on aortic lipoprotein lipid peroxidation and atherosclerosis in apolipoprotein E-deficient (apoE-/-) mice fed a high-fat diet. Hydroperoxides of cholesteryl esters and triacylglycerols (together referred to as LOOH) and their corresponding alcohols were used as the marker for lipoprotein lipid oxidation. Atherosclerosis was assessed by morphometry at the aortic root, proximal and distal arch, and the descending thoracic and abdominal aorta. Compared to controls, CoQ10-treatment increased plasma coenzyme Q, ascorbate, and the CoQ10H2:CoQ10 + CoQ10H2 ratio, decreased plasma alpha-tocopherol (alpha-TOH), and had no effect on cholesterol and cholesterylester alcohols (CE-OH). Plasma from CoQ10-supplemented mice was more resistant to ex vivo lipid peroxidation. CoQ10 treatment increased aortic coenzyme Q and alpha-TOH and decreased the absolute concentration of LOOH, whereas tissue cholesterol, cholesteryl esters, CE-OH, and LOOH expressed per bisallylic hydrogen-containing lipids were not significantly different. CoQ10-treatment significantly decreased lesion size in the aortic root and the ascending and the descending aorta. Together these data show that CoQ10 decreases the absolute concentration of aortic LOOH and atherosclerosis in apoE-/- mice.     

Endothelial lipase modulates HDL but has no effect on atherosclerosis development in apoE-/- and LDLR-/- mice

Endothelial lipase (EL) is a determinant of high density lipoprotein-cholesterol (HDL-C) level, which is negatively correlated with atherosclerosis susceptibility. We found no difference in aortic atherosclerotic lesion areas between 26-week-old EL+/+ apolipoprotein E-deficient (apoE-/-) and EL-/- apoE-/- mice. To more firmly establish the role of EL in atherosclerosis, we extended our study to EL-/- and EL+/+ low density lipoprotein receptor-deficient (LDLR-/-) mice that were fed a Western diet. Morphometric analysis again revealed no difference in atherosclerosis lesion area between the two groups. Compared with EL+/+ mice, we found increased HDL-C in EL-/- mice with apoE-/- or LDLR-/- background but no difference in macrophage content between lesions of EL-/- and EL+/+ mice in apoE-/- or LDLR-/- background. EL inactivation had no effect on hepatic mRNAs of proteins involved in reverse cholesterol transport. A survey of lipid homeostasis in EL+/+ and EL-/- macrophages revealed that oxidized LDL-induced ABCA1 was attenuated in EL-/- macrophages. This potentially proatherogenic change may have nullified any minor protective increase of HDL in EL-/- mice. Thus, although EL modulated lipoprotein profile in mice, there was no effect of EL inactivation on atherosclerosis development in two hyperlipidemic atherosclerosis-prone mouse models.     

Effects of ANG II type 1 and 2 receptors on oxidative stress,renal NADPH oxidase,and SOD expression

Oxidative stress accompanies angiotensin (ANG) II infusion, but the role of ANG type 1 vs. type 2 receptors (AT1-R and AT2-R, respectively) is unknown. We infused ANG II subcutaneously in rats for 1 wk. Excretion of 8-isoprostaglandin F2alpha (8-Iso) and malonyldialdehyde (MDA) were related to renal cortical mRNA abundance for subunits of NADPH oxidase and superoxide dismutases (SODs) using real-time PCR. Subsets of ANG II-infused rats were given the AT1-R antagonist candesartan cilexetil (Cand) or the AT2-R antagonist PD-123,319 (PD). Compared to vehicle (Veh), ANG II increased 8-Iso excretion by 41% (Veh, 5.4 +/- 0.8 vs. ANG II, 7.6 +/- 0.5 pg/24 h; P < 0.05). This was prevented by Cand (5.6 +/- 0.5 pg/24 h; P < 0.05) and increased by PD (15.8 +/- 2.0 pg/24 h; P < 0.005). There were similar changes in MDA excretion. Compared to Veh, ANG II significantly (P < 0.005) increased the renal cortical mRNA expression of p22phox (twofold), Nox-1 (2.6-fold), and Mn-SOD (1.5-fold) and decreased expression of Nox-4 (2.1-fold) and extracellular (EC)-SOD (2.1-fold). Cand prevented all of these changes except for the increase in Mn-SOD. PD accentuated changes in p22phox and Nox-1 and increased p67phox. We conclude that ANG II infusion stimulates oxidative stress via AT1-R, which increases the renal cortical mRNA expression of p22phox and Nox-1 and reduces abundance of Nox-4 and EC-SOD. This is offset by strong protective effects of AT2-R, which are accompanied by decreased expression of p22phox, Nox-1, and p67phox.     

Oxidative stress is decreased in off-pump versus on-pump coronary artery surgery

Oxidative stress occurs in patients undergoing coronary artery bypass operation. The aim of this study was to investigate the difference in oxidative stress in off-pump versus on-pump coronary artery bypass surgery. In the present study, in serial blood samples, plasma malondialdehyde (MDA) as index of lipid peroxidation, red blood cells glutathione peroxidase (GPx) and superoxide dismutase (SOD) were measured to compare the extent of oxidative stress in 30 patients undergoing OPCAB (off-pump coronary artery bypass grafting), 12 patients undergoing CABG (on-pump coronary artery bypass grafting) and 18 healthy controls. In CABG group, MDA levels increased significantly from 2.87 +/- 0.62 nmol/mL before anesthesia and 2.87 +/- 0.65 nmol/mL after anesthesia to 3.05 +/- 0.66 nmol/mL after ischemia (p < 0.05). Similarly, SOD levels also elevated significantly from 661.58 +/- 78.70 U/g Hb before anesthesia and 659.42 +/- 81.21 U/g Hb anesthesia induction to 678.08 +/- 75.80 U/g Hb after ischemia (p < 0.01, p < 0.01, respectively). In OPCAB group, only SOD levels increased from 581.73 +/- 86.24 U/g Hb anesthesia induction to 590.90 +/- 88.90 U/g Hb after reperfusion (p < 0.05). Glutathione peroxidase levels were not changed according to blood collection times in both of CABG group or OPCAB group (p > 0.05). Our results show that only mild signs of oxidative stress is found after reperfusion in OPCAB operation compared with CABG operation. Further studies are needed in order to confirm this hypothesis.