Low-cholesterol and high-fat diets reduce atherosclerotic lesion development in ApoE-knockout mice

Dietary proteins modulate high-density lipoprotein characteristics in a sex-specific way in Apoe-deficient mice

OBJECTIVES

The type and amount of dietary protein have become a topic of renewed interest, considering their involvement in several diseases. However, little attention has been devoted to the effect of avian proteins despite their wide human consumption. In a previous study, we saw that compared with soybean protein, the consumption of avian proteins, depending on sex, resulted in similar or lower atherosclerosis with a higher paraoxonase 1 activity, an antioxidant enzyme carried by high-density lipoproteins (HDL). This suggests that under these conditions, the HDL lipoproteins may undergo important changes. The aim of this research was to study the influence of soybean, chicken, and turkey proteins on the characteristics of HDL.

METHODS

Male and female Apoe-deficient mice were fed purified Western diets based on the AIN-93 diet, differing only in the protein source, for 12 wk. After this period, blood and liver samples were taken for analysis of HDL composition and hepatic expression of genes related to HDL metabolism (Abca1, Lcat, Pltp, Pon1, and Scarb1). Depending on sex, these genes define a different network of interactions. Females consuming the turkey protein-containing diet showed decreased atherosclerotic foci, which can be due to larger very-low-density lipoproteins (VLDLs) calculated by molar ratio triacylglycerols/VLDL cholesterol and higher expression of Lcat. In contrast, in males, a higher ratio of paraoxonase1 to apolipoprotein A1 decreased the oxidative status of the different lipoproteins, and augmented Abca1 expression was observed.

CONCLUSIONS

The source of protein has an effect on the development of atherosclerosis depending on sex by modifying HDL characteristics and the expression of genes involved in their properties.

Mouse models of atherosclerosis in translational research

Atherosclerotic cardiovascular disease (CVD), the major cause of premature human mortality, is a chronic and progressive metabolic and inflammatory disease in large- and medium-sized arteries. Mouse models are widely used to gain mechanistic insights into the pathogenesis of atherosclerosis and have facilitated the discovery of anti-atherosclerotic drugs. Despite promising preclinical studies, many drug candidates have not translated to clinical use because of the complexity of disease patho-mechanisms including lipid metabolic traits and inflammatory, genetic, and hemodynamic factors. We review the current preclinical utility and translation potential of traditional [apolipoprotein E (APOE)- and low-density lipoprotein (LDL) receptor (LDLR)-deficient mice] and emerging mouse models that include partial carotid ligation and AAV8-Pcsk9-D377Y injection in atherosclerosis research and drug discovery. This article represents an important resource in atherosclerosis research.

Hepatic Synaptotagmin 1 is involved in the remodelling of liver plasma- membrane lipid composition and gene expression in male Apoe-deficient mice consuming a Western diet

BACKGROUND AND AIMS

The molecular mechanisms by which the liver develops steatotic disease still remain unclear. Previous studies using nutritional and genetic models of hepatic steatosis in mice showed that liver synaptotagmin 1 (Syt1) expression was associated with lipid droplet area. Hepatic Syt1 overexpression was used as a tool to explore its effect on hepatic and plasma lipids.

METHODS AND RESULTS

To find out a cause-effect, hepatic mouse Syt1 mRNA was cloned into a vector driving hepatocyte-specific expression and administered by hydrodynamic injection to male Apoe-deficient mice fed on a Western diet, the latter as a model of rapid spontaneous steatosis development. Hepatic microsomal, large vesicle, lysosomal and plasma membrane fractions were enriched in SYT1 protein following gene overexpression. In these conditions, very low density lipoprotein esterified cholesterol increased. Likewise, the transgene caused an alteration in lipid droplet surface and a positive correlation between Syt1 expression and hepatic total cholesterol content. A lipidomic approach evidenced a decrease in lysophosphatidylcholine, phosphatidylcholine and triglycerides in isolated plasma membrane fraction. Expressions of genes involved in biosynthesis of bile acids, fatty acid metabolism, lipoprotein dynamics and vesicular transport were modified by the increased SYT1 expression.

CONCLUSIONS

These results indicate that this protein is involved in hepatic management of lipids and in the regulation of genes involved in lipid metabolism.

Is Extra Virgin Olive Oil an Ally for Women's and Men's Cardiovascular Health?

Noncommunicable diseases are long-lasting and slowly progressive and are the leading causes of death and disability. They include cardiovascular diseases (CVD) and diabetes mellitus (DM) that are rising worldwide, with CVD being the leading cause of death in developed countries. Thus, there is a need to find new preventive and therapeutic approaches. Polyphenols seem to have cardioprotective properties; among them, polyphenols and/or minor polar compounds of extra virgin olive oil (EVOO) are attracting special interest. In consideration of numerous sex differences present in CVD and DM, in this narrative review, we applied "gender glasses." Globally, it emerges that olive oil and its derivatives exert some anti-inflammatory and antioxidant effects, modulate glucose metabolism, and ameliorate endothelial dysfunction. However, as in prescription drugs, also in this case there is an important gender bias because the majority of the preclinical studies are performed on male animals, and the sex of donors of cells is not often known; thus a sex/gender bias characterizes preclinical research. There are numerous clinical studies that seem to suggest the benefits of EVOO and its derivatives in CVD; however, these studies have numerous limitations, presenting also a considerable heterogeneity across the interventions. Among limitations, one of the most relevant in the era of personalized medicine, is the non-attention versus women that are few and, also when they are enrolled, sex analysis is lacking. Therefore, in our opinion, it is time to perform more long, extensive and lessheterogeneous trials enrolling both women and men.

Rosuvastatin Prevents the Exacerbation of Atherosclerosis in Ligature-Induced Periodontal Disease Mouse Model

Periodontitis is a local and systemic inflammatory condition and a risk factor of atherosclerosis, but no studies investigated the effect of a statin on atherogenesis affected by severe periodontitis. In this study, we investigated the effect of rosuvastatin (RSV) on atherogenesis in Apolipoprotein E-deficient mice receiving silk ligature placement around the maxillary second molars. Mice with the ligature placement developed severe periodontitis and vascular inflammation. RSV significantly inhibited the development of periodontitis and vascular inflammation and remarkably blocked the increased lipid deposition and the atherogenic gene expression in the arterial wall and aortic sinus induced by severe periodontitis. To understand the mechanistic effect of RSV on periodontitis-associated atherogenesis, we investigated the in vitro effect of RSV on various effect of TNF-α, a major proinflammatory cytokine for periodontitis and atherogenesis. We found that RSV notably inhibited the TNF-α-induced osteoclast formation, endothelial cell phenotypic changes, foam cell formation, and the expression of CD47 and other oncogenes in arterial smooth muscle cells. Taken together, our study indicates that RSV prevents the exacerbation of atherosclerosis induced periodontitis by inhibiting local, systemic and vascular inflammation, as well as the expression of CD47 from arterial smooth muscle cells in mice.

Extra-Virgin Olive Oil with Natural Phenolic Content Exerts an Anti-Inflammatory Effect in Adipose Tissue and Attenuates the Severity of Atherosclerotic Lesions in Ldlr-/-.Leiden Mice

SCOPE

The present study investigates the effect of olive oils with different phenolic content in high-fat diets (HFDs) on hypertrophy and inflammation in adipose tissue and associated atherosclerosis, in the context of obesity.

METHODS AND RESULTS

Ldlr-/-.Leiden mice were fed three different HFDs for 32 weeks and were compared with mice fed the standard low-fat diet (LFD). The different fats provided in the HFDs were lard (HFD-L), extra-virgin olive oil (EVOO; 79 mg kg^-1 of phenolic compounds, HFD-EVOO), or EVOO rich in phenolic compounds (OL, 444 mg kg^-1 of phenolic compounds, HFD-OL). All HFD-fed mice became obese, but only HFD-L-induced adipocyte hypertrophy. HFD-EVOO mice exhibited the greatest levels of Adiponectin in adipose tissue and presented atherosclerotic lesions similar to the LFD group, with a very low count of monocyte/macrophage compared with HFD-L and HFD-OL mice. Enrichment of the phenolic content of olive oil reduced the secretion of nitrites/nitrates in the aorta, but atherosclerosis was not attenuated in HFD-OL mice compared to other HFD mice.

CONCLUSION

Consumption of olive oil with a natural content of phenolic compounds attenuates adipose tissue hypertrophy and inflammation and exerts antiatherosclerotic effects in mice. A higher phenolic content of olive oil did not provide further benefits in the prevention of atherosclerosis.

Exploring the effects of the atherosclerosis progression and the choice of affected arteries in the design of experiments with Apolipoprotein E-deficient mice

The objective of this study is to explore the longitudinal progression of atherosclerosis and the correlation between methods to measure the lesion in apolipoprotein E-deficient mice. Atherosclerosis progression was assessed by measurements of foam cell-rich depositions in their proximal aortas, and/or in surgically excised arteries, to assess the histological luminal narrowing. A longitudinal study was performed by comparing the values for carotid, aorta, and femoral and iliac arteries using common histological techniques. There were no significant differences in progression between different arteries, but correlation with the classical measurement of atherosclerosis in the aortic root was poor. Each laboratory requires specific standardization. Carotid arteries were sensitive to atherosclerosis in these mice, and progression was exponential. In conclusion, morphometric data show the importance of the choice of the duration of treatment, the appropriate controls, and the age at which to begin the experiments.

Sulfur amino acids and atherosclerosis: a role for excess dietary methionine

The homocysteine theory of arteriosclerosis received credence when it was shown that after a methionine load, circulating homocysteine-cysteine concentrations were higher in cardiovascular disease patients than in healthy controls. Subsequent studies showing associations between homocysteine and coronary artery disease, stroke and cognitive impairment, relied on small increases in homocysteine concentration unlike the very high homocysteine seen in the rare genetic disorders that lead to homocystinuria and much higher homocysteine levels. Subsequent studies in cell culture, animals, and humans showed that a variety of cardiovascular adverse effects of "high homocysteine" introduced either as a nonphysiological bolus or as a methionine load led to high homocysteine. We fed apolipoprotein E-deficient mice diets designed to achieve three conditions: (1) high methionine intake with normal blood homocysteine, (2) high methionine intake with B vitamin deficiency and hyperhomocysteinemia, and (3) normal methionine intake with both B vitamin deficiency and hyperhomocysteinemia. We found that the mice fed methionine-rich diets had significant atheromatous pathology in the aortic arch even with normal plasma homocysteine levels. Mice fed B vitamin-deficient diets developed severe hyperhomocysteinemia but without any increase in vascular pathology. Our findings suggest that even moderate increases in methionine intake are atherogenic in susceptible mice while high plasma homocysteine is not.

Reduction of mouse atherosclerosis by urokinase inhibition or with a limited-spectrum matrix metalloproteinase inhibitor

AIMS

Elevated activity of urokinase plasminogen activator (uPA) and MMPs in human arteries is associated with accelerated atherosclerosis, aneurysms, and plaque rupture. We used Apoe-null mice with macrophage-specific uPA overexpression (SR-uPA mice; a well-characterized model of protease-accelerated atherosclerosis) to investigate whether systemic inhibition of proteolytic activity of uPA or a subset of MMPs can reduce protease-induced atherosclerosis and aortic dilation.

METHODS AND RESULTS

SR-uPA mice were fed a high-fat diet for 10 weeks and treated either with an antibody inhibiting mouse uPA (mU1) or a control antibody. mU1-treated mice were also compared with PBS-treated non-uPA-overexpressing Apoe-null mice. Other SR-uPA mice were treated with one of three doses of a limited-spectrum synthetic MMP inhibitor (XL784) or vehicle. mU1 reduced aortic root intimal lesion area (20%; P = 0.05) and aortic root circumference (12%; P = 0.01). All XL784 doses reduced aortic root intimal lesion area (22-29%) and oil-red-O-positive lesion area (36-42%; P < 0.05 for all doses and both end points), with trends towards reduced aortic root circumference (6-10%). Neither mU1 nor XL784 significantly altered percent aortic surface lesion coverage. Several lines of evidence identified MMP-13 as a mediator of uPA-induced aortic MMP activity.

CONCLUSIONS

Pharmacological inhibition of either uPA or selected MMPs decreased atherosclerosis in SR-uPA mice. uPA inhibition decreased aortic dilation. Differential effects of both agents on aortic root vs. distal aortic atherosclerosis suggest prevention of atherosclerosis progression vs. initiation. Systemic inhibition of uPA or a subset of MMPs shows promise for treating atherosclerosis.

Dietary squalene increases high density lipoprotein-cholesterol and paraoxonase 1 and decreases oxidative stress in mice

BACKGROUND AND PURPOSE

Squalene, the main hydrocarbon in the unsaponifiable fraction of virgin olive oil, is involved in cholesterol synthesis and it has been reported to own antiatherosclerotic and antiesteatosic effects. However, the squalene's role on lipid plasma parameters and the influence of genotype on this effect need to be addressed.

EXPERIMENTAL APPROACHES

Three male mouse models (wild-type, Apoa1- and Apoe- deficient) were fed chow semisynthetic diets enriched in squalene to provide a dose of 1 g/kg during 11 weeks. After this period, their plasma parameters and lipoprotein profiles were analyzed.

KEY RESULTS

Squalene administration at a dose of 1 g/kg showed decreased reactive oxygen species in lipoprotein fractions independently of the animal background and caused an specific increase in high density lipoprotein (HDL)-cholesterol levels, accompanied by an increase in phosphatidylcholine and paraoxonase 1 and no changes in apolipoproteins A1 and A4 in wild-type mice. In these mice, the cholesterol increase was due to its esterified form and associated with an increased hepatic expression of Lcat. These effects were not observed in absence of apolipoprotein A1. The increases in HDL- paraoxonase 1 were translated into decreased plasma malondialdehyde levels depending on the presence of Apolipoprotein A1.

CONCLUSIONS AND IMPLICATIONS

Dietary squalene promotes changes in HDL- cholesterol and paraoxonase 1 and decreases reactive oxygen species in lipoproteins and plasma malondialdehyde levels, providing new benefits of its intake that might contribute to explain the properties of virgin olive oil, although the phenotype related to apolipoproteins A1 and E may be particularly relevant.

Extra virgin olive oil intake delays the development of amyotrophic lateral sclerosis associated with reduced reticulum stress and autophagy in muscle of SOD1G93A mice

Amyotrophic lateral sclerosis is a neurodegenerative disease associated with mutations in antioxidant enzyme Cu/Zn-superoxide dismutase 1. Albeit there is no treatment for this disease, new insights related to an exacerbated lipid metabolism have been reported. In connection with the hypermetabolic lipid status, the hypothesis whether nature of dietary fat might delay the progression of the disease was tested by using a transgenic mouse that overexpresses the human SOD1G93A variant. For this purpose, SOD1G93A mice were assigned randomly to one of the following three experimental groups: (1) a standard chow diet (control, n=21), (2) a chow diet enriched with 20% (w/w) extra virgin olive oil (EVOO, n=22) and (3) a chow diet containing 20% palm oil (palm, n=20). They received the diets for 8 weeks and the progression of the disease was assessed. On the standard chow diet, average plasma cholesterol levels were lower than those mice receiving the high-fat diets. Mice fed an EVOO diet showed a significant higher survival and better motor performance than control mice. EVOO group mice survived longer and showed better motor performance and larger muscle fiber area than animals receiving palm. Moreover, the EVOO-enriched diet improved the muscle status as shown by expression of myogenic factors (Myod1 and Myog) and autophagy markers (LC3 and Beclin1), as well as diminished endoplasmic reticulum (ER) stress through decreasing Atf6 and Grp78. Our results demonstrate that EVOO may be effective in increasing survival rate, improving motor coordination together with a potential amelioration of ER stress, autophagy and muscle damage.

Postprandial changes in high density lipoproteins in rats subjected to gavage administration of virgin olive oil

Background and Aims

The present study was designed to verify the influence of acute fat loading on high density lipoprotein (HDL) composition, and the involvement of liver and different segments of small intestine in the changes observed.

Methods and Results

To address these issues, rats were administered a bolus of 5-ml of extra-virgin olive oil and sacrificed 4 and 8 hours after feeding. In these animals, lipoproteins were analyzed and gene expressions of apolipoprotein and HDL enzymes were assessed in duodenum, jejunum, ileum and liver. Using this experimental design, total plasma and HDL phospholipids increased at the 8-hour-time-point due to increased sphingomyelin content. An increase in apolipoprotein A4 was also observed mainly in lipid-poor HDL. Increased expression of intestinal Apoa1, Apoa4 and Sgms1 mRNA was accompanied by hepatic decreases in the first two genes in liver. Hepatic expression of Abcg1, Apoa1bp, Apoa2, Apoe, Ptlp, Pon1 and Scarb1 decreased significantly following fat gavage, while no changes were observed for Abca1, Lcat or Pla2g7. Significant associations were also noted for hepatic expression of apolipoproteins and Pon1. Manipulation of postprandial triglycerides using an inhibitor of microsomal transfer protein -CP-346086- or of lipoprotein lipase –tyloxapol- did not influence hepatic expression of Apoa1 or Apoa4 mRNA.

Conclusion

All these data indicate that dietary fat modifies the phospholipid composition of rat HDL, suggesting a mechanism of down-regulation of hepatic HDL when intestine is the main source of those particles and a coordinated regulation of hepatic components of these lipoproteins at the mRNA level, independently of plasma postprandial triglycerides.

In comparison with palm oil, dietary nut supplementation delays the progression of atherosclerotic lesions in female apoE-deficient mice

Epidemiological studies have demonstrated the benefits of nut consumption on cardiovascular risk factors and CHD, attributed to their fatty acid profile, rich in unsaturated fatty acids, and also to other nutrients. The effect of nuts on atherosclerotic lesions was studied in female and male apoE-knockout mice fed a diet supplemented with 3 % (w/w) mixed nuts (mix: almonds, hazelnuts and walnuts in a proportion of 0.25:0·25:0.50, respectively), and compared with mice receiving an isoenergetic diet of similar fat content provided as palm oil. After 12 weeks, plasma lipid parameters and aortic lesions were measured. Males receiving nuts had lower plasma cholesterol than the palm oil group, and both sex groups had lower plasma non-HDL-cholesterol and lower content of reactive oxygen species in LDL than mice receiving the palm oil diet, the latter decrease being more pronounced in females than in males. Females consuming the nut diet showed a smaller aortic lesion area than those consuming palm oil, whereas no differences were observed in males. In females, hepatic paraoxonase 2 (Pon2) mRNA increased, and no change was observed in prenylcysteine oxidase 1 (Pcyox1) expression after the consumption of the nut-containing diet. In addition, aortic atherosclerotic lesions correlated directly with total plasma cholesterol and inversely with hepatic Pon2 expression. The results suggest that the beneficial effect of nut intake in female apoE-deficient mice may be attributed to reduced non-HDL-cholesterol levels and enhanced PON2 antioxidant activity.

Differential response of two models of genetically modified mice fed with high fat and cholesterol diets: relationship to the study of non-alcoholic steatohepatitis

Research on the molecular basis of the hepatic alterations associated to obesity is dependent on the availability of suitable animal models. Apolipoprotein E deficient mice (ApoE(-/-)) and LDL-receptor deficient mice (LDLr(-/-)) develop steatosis and steatohepatitis when given pro-atherogenic diets. However, previous data suggest that these two models are not completely interchangeable, and that their metabolic phenotype may partially differ in response to nutrient stimuli. The present study further investigates this question, by comparing changes in hepatic inflammation, lipoprotein metabolism, and their related gene expressions. LDLr(-/-) mice were more susceptible to the development of obesity and hepatic steatosis, while the ApoE(-/-) model increased the amount of macrophages and inflammatory nodules in the liver. These changes were accompanied by a differential expression of selected members of the MAPK family and PPARs in the liver.

Sex as a profound modifier of atherosclerotic lesion development in apolipoprotein E-deficient mice with different genetic backgrounds

AIM

Research suggests that sex may condition atherosclerosis development against different genetic backgrounds. This study addresses the hypothesis that this effect would be exerted by changes in the different apolipoproteins present in high-density lipoproteins.

METHODS

ApoE-deficient mice of both sexes with Ola 129 and C57BL/6J genetic backgrounds were fed a chow diet for 14 weeks. At the end of the dietary intervention, the development of atherosclerotic lesions, apolipoproteins, lipid metabolism, inflammation and paraoxonase were assessed.

RESULTS

Differences between atherosclerotic lesions in Ola 129 and C57BL/6J strains of apoE-deficient mice were sex-dependent and were only statistically significant in females. Plasma levels of HDL cholesterol and apolipoproteins related to these lipoparticles, such as apoA-I, apoA-II, apoA-IV, apoA-V and apoJ, were significantly different between these two strains and there were sex-related differences in some of these apolipoproteins. Hepatic steatosis was also related to the strain and was independent of sex. In females, changes in HDL cholesterol and apolipoproteins A-I and A-II were important determinants of atherosclerosis, while this was not the case in males.

CONCLUSIONS

Our results demonstrate that atherosclerosis-related differences between Ola129 and C57BL/6J genetic backgrounds in apoE-deficient mice are sex-dependent and that this finding is explained by the differences in HDL cholesterol and its apolipoprotein components, mainly apoA-I and A-II. Overall, our findings highlight the importance of taking sex into account in the analysis of atherosclerosis and lipid metabolism in animal models.

Expression of cytokine genes in the aorta is altered by the deficiency in MCP-1: effect of a high-fat, high-cholesterol diet

BACKGROUND

Monocyte chemoattractant protein-1 (MCP-1) facilitates the recruitment of monocytes/macrophages into vascular intima, and it is probably involved in the regulation of other signaling pathways relevant to the pathogenesis of arteriosclerosis and metabolic disturbances. However, chemokines are redundant. Consequently, the protective effect of MCP-1 deficiency may be mediated by changes in other cytokine signals.

METHODS AND RESULTS

Changes in the pattern of gene expression in the aorta were evaluated in LDLr(-/-) and MCP-1(-/-) LDLr(-/-) mice fed either chow or Western-style diet. Functional analyses were used to characterize the pathways affected and to identify biological processes in which MCP-1 may play an additional role. Some data also suggest that MCP-5 may act as a surrogate for MCP-1 deletion. Arteriosclerosis lesion and plaque composition are associated with enrichment in the cytokine-cytokine receptor interaction pathway.

CONCLUSIONS

There is a complex network of interactions linking MCP-1 and other cytokines. The lack of MCP-1 limits the aortic response to atherogenic stimuli, but does not completely protect against neointima formation. Activation of alternative inflammatory pathways in the vascular wall in response to MCP-1 deficiency should be considered to fully understand the actual role of this chemokine.

Blockade of scavenger receptor class B type I raises high density lipoprotein cholesterol levels but exacerbates atherosclerotic lesion formation in apolipoprotein E deficient mice

Recent accumulating evidence supports the concept that raising high-density lipoprotein (HDL) may represent an additional therapeutic target for prevention of cardiovascular disease. Scavenger receptor class B type I plays a critical role in plasma HDL cholesterol concentration and structure. This study investigated the effect of scavenger receptor class B type I blockade by a synthetic scavenger receptor class B type I blocker on plasma lipids and atherosclerosis lesion formation in apolipoprotein E (apoE)-deficient mice. N-[4-(4-tert-Butoxycarbonylpiperazin-1-yl)phenyl]-(2-chloro-5-nitrophenyl)carboxamide (R-138329), a novel scavenger receptor class B type I blocker, was identified by screening with a half-maximal inhibitory potency (IC50 value) of around 1 μM in scavenger receptor class B type I-expressing COS-1 cells. Male apoE-deficient mice were fed a chow diet with or without R-138329 (0.01-0.10%, approximately 10–100 mg kg−1, n = 9 or 10) for 12 weeks. Compared with control, treatment with R-138329 at 0.10% caused significant (P &lt; 0.05) increases in plasma HDL cholesterol levels, and decreases in non-HDL cholesterol and triglyceride levels. Furthermore, R-138329 at 0.01% significantly increased the extent of atherosclerotic lesion formation in the aorta by 98% (P &lt; 0.05), while favourable changes in plasma lipid parameters were achieved. The results of quantitative analysis of atherosclerosis lesion areas were: control, 102691 ±22871 μm2 (n = 10); R-138329 0.01%, 119792 ± 30842 μm2 (n = 9); R-138329 0.03%, 141346 ± 21934 μm2 (n = 10); and R-138329 0.10% 203732 ± 36326 μm2 (n = 10). To clarify the mechanistic basis underlying this preferential deterioration, we examined the potential impact on closely related cellular functions. Further studies revealed that the active metabolite of R-138329 inhibited scavenger receptor class B type I-mediated cholesterol efflux. This study demonstrates for the first time pharmacological blockade of scavenger receptor class B type I in apoE-deficient mice. Blockade of scavenger receptor class B type I deteriorates atherosclerotic lesion formation in apoE-deficient mice even though it favourably affects plasma lipid parameters such as raising HDL cholesterol and decreasing non-HDL cholesterol. These results provide new insights for pharmaceutical industry research and development issues.

Microarray analysis of hepatic gene expression identifies new genes involved in steatotic liver

Trans-10, cis-12-conjugated linoleic acid (CLA)-enriched diets promote fatty liver in mice, while cis-9, trans-11-CLA ameliorates this effect, suggesting regulation of multiple genes. To test this hypothesis, apoE-deficient mice were fed a Western-type diet enriched with linoleic acid isomers, and their hepatic gene expression was analyzed with DNA microarrays. To provide an initial screening of candidate genes, only 12 with remarkably modified expression between both CLA isomers were considered and confirmed by quantitative RT-PCR. Additionally mRNA expression of 15 genes involved in lipid metabolism was also studied. Ten genes (Fsp27, Aqp4, Cd36, Ly6d, Scd1, Hsd3b5, Syt1, Cyp7b1, and Tff3) showed significant associations among their expressions and the degree of hepatic steatosis. Their involvement was also analyzed in other models of steatosis. In hyperhomocysteinemic mice lacking Cbs gene, only Fsp27, Cd36, Scd1, Syt1, and Hsd3b5 hepatic expressions were associated with steatosis. In apoE-deficient mice consuming olive-enriched diet displaying reduction of the fatty liver, only Fsp27 and Syt1 expressions were found associated. Using this strategy, we have shown that expression of these genes is highly associated with hepatic steatosis in a genetic disease such as Cbs deficiency and in two common situations such as Western diets containing CLA isomers or a Mediterranean-type diet. Conclusion: The results highlight new processes involved in lipid handling in liver and will help to understand the complex human pathology providing new proteins and new strategies to cope with hepatic steatosis.

Dried plums (prunes) reduce atherosclerosis lesion area in apolipoprotein E-deficient mice

Dried plums are a fruit high in pectin with substantial antioxidant activity. Previous studies in rats and man indicate that dried plums or plum fibre lower liver and plasma cholesterol, respectively. The apoE-deficient mouse, which develops atherosclerotic lesions rapidly when fed cholesterol, was used to determine the ability of dried plums to reduce atherosclerosis. Diets containing 0.15% cholesterol and either 0 (B+C), 4.75% (Lo DP) or 9.5% (Hi DP) dried plum powder were fed for 5 months. An additional group fed the basal diet without cholesterol (B-C) was included as a negative control. Arterial trees were dissected, stained to visualize lesions, and lesion area was quantitated by imaging software. Urinary thiobarbituric acid-reactive substances (TBARS) excretion and serum amyloid P-component (SAP) were measured as indicators of oxidative stress and inflammation, respectively. Final serum cholesterol was significantly increased and serum TAG decreased in the B+C group and dried plum groups relative to the B-C group. Percentage arterial tree atherosclerotic lesion area was significantly lower in the B-C and Lo DP groups compared to the B+C group (P<0.05), with a trend for a difference between the B+C and Hi DP groups (P=0.075). SAP concentration was significantly lower in the B-C and Lo DP groups with the Hi DP group trending lower than the B+C group. Urinary TBARS excretion did not differ among the groups. These results suggest that consuming dried plums may help slow the development of atherosclerosis.

Sesame oil does not show accumulatively enhanced protection against oxidative stress-associated hepatic injury in septic rats

BACKGROUND

Sepsis is one of the major causes of death reported in intensive care units. A daily supplement of sesame oil for 1 week significantly attenuates oxidative stress-associated hepatic injury in septic rats. However, the excess intake of sesame oil may be associated with a health risk. This study investigates the effect of accumulative sesame oil on oxidative stress-associated hepatic injury after cecal ligation and puncture in rats.

METHODS

Sesame oil was administered daily (4 mL/kg/d, orally) to rats, and the total intake of sesame oil ranged from 0 (control) to 140 mL/kg before cecal ligation and puncture in 9 groups of rats. Oxidative stress was examined by determining the levels of lipid peroxidation and glutathione. Hepatic injury was evaluated by measuring serum levels of aspartate aminotransferase and alkaline phosphatase.

RESULTS

Rats that received sesame oil for 4 and 5 weeks had a lower body weight gain compared with those that received saline. Lipid peroxidation was decreased in the 20-mL/kg and 28-mL/kg groups, but it was increased in the 140-mL/kg group compared with the control group. Glutathione levels were increased in the < or =28-mL/kg groups compared with the control group. Serum levels of aspartate aminotransferase and alkaline phosphatase were reduced in the < or =28-mL/kg groups compared with the control group.

CONCLUSION

Sesame oil does not demonstrate accumulatively enhanced protection against oxidative stress-associated hepatic injury after cecal ligation and puncture in rats.

Deficiency of adipose differentiation-related protein impairs foam cell formation and protects against atherosclerosis

Foam cells are a hallmark of atherosclerosis. However, it is unclear whether foam cell formation per se protects against atherosclerosis or fuels it. In this study, we investigated the role of adipose differentiation-related protein (ADFP), a major lipid droplet protein (LDP), in the regulation of foam cell formation and atherosclerosis. We show that ADFP expression facilitates foam cell formation induced by modified lipoproteins in mouse macrophages in vitro. We show further that Adfp gene inactivation in apolipoprotein E-deficient (ApoE(-/-)) mice reduces the number of lipid droplets in foam cells in atherosclerotic lesions and protects the mice against atherosclerosis. Moreover, transplantation of ADFP-null bone marrow-derived cells effectively attenuated atherosclerosis in ApoE(-/-) mice. Deficiency of ADFP did not cause a detectable compensatory increase in the other PAT domain proteins in macrophages in vitro or in vivo. Mechanistically, ADFP enables the macrophage to maintain its lipid content by hindering lipid efflux. We detected no significant difference in lesion composition or in multiple parameters of inflammation in macrophages or in their phagocytic activity between mice with and without ADFP. In conclusion, Adfp inactivation in ApoE(-/-) background protects against atherosclerosis and appears to be a relatively pure model of impaired foam cell formation.

Squalene in a sex-dependent manner modulates atherosclerotic lesion which correlates with hepatic fat content in apoE-knockout male mice

BACKGROUND

Squalene is an intermediate of cholesterol biosynthesis which can be obtained from the diet where it is abundant, for example, in olive oil. The effect of this isoprenoid on the development of atherosclerosis was investigated on apoE-knockout mice.

METHODS AND RESULTS

Two groups of animals, separated according to sex, were fed on standard chow diet: the control group receiving only vehicle and the second group an aqueous solution of squalene to provide a dose of 1g/kg/day in male and female mice. This treatment was maintained for 10 weeks. At the end of this period, plasma lipid parameters, oxidative stress markers and hepatic fat were measured as well as cross-sectional lesion area of aortic root in both groups. Data showed that in males squalene feeding reduced atherosclerotic lesion area independently of plasma lipids and activation of circulating monocytes. In contrast, squalene intake did not decrease lesion area in females, despite reducing plasma cholesterol and triglycerides, isoprostane and percentage of Mac-1 expressing white cells. In males, atherosclerotic lesion area was positively and significantly associated with hepatic fat content and the plasma triglycerides were also strongly associated with liver weight.

CONCLUSIONS

These results indicate that administration of squalene modulates lesion development in a gender specific manner, and that accumulation of hepatic fat by liver is highly correlated with lesion progression in males. Hence, squalene administration could be used as a safe alternative to correct hepatic steatosis and atherosclerosis particularly in males.

Simvastatin reverses the hypertension of heterozygous mice lacking cystathionine beta-synthase and apolipoprotein A-I

Double heterozygous mice lacking Apoa1 and Cbs genes show mild hyperhomocysteinemia in combination with hypoalphalipoproteinemia. This situation leads to a moderate hypertension associated with a dysregulation in nitric oxide metabolism. The aim of this study was to investigate the potential beneficial effects of statin treatment in these mice. After 4 weeks of simvastatin administration, plasma parameters; apolipoproteins A-I, A-II and A-IV; lipid profile; and blood pressure were assessed, Western blotting was performed in the aorta of these mice to measure endothelial nitric oxide synthase and caveolin-1 content. The high blood pressure level present in the double heterozygous group was corrected down to that of the wild-type group after simvastatin treatment (124+/-7.7 vs. 109+/-11.2 mmHg, p<0.01). Concomitant with this effect, an increase in nitric oxide levels was observed in these double heterozygous mice receiving simvastatin treatment probably mediated in part by a decrease in caveolin-1 levels. Blood pressure changes appeared to be independent of the arylesterase activity of paraoxonase or the lipid content. Another remarkable result was the significant increase in apoA-IV content in animals receiving simvastatin, an effect considered to be protective for the endothelium. In conclusion, the results of this study demonstrate that the use of simvastatin can improve blood pressure control in mice with elevated homocysteinemia and low levels of apoA-I, and this effect is mediated by mechanisms independent of plasma lipids and related to nitric oxide levels.

Protein kinases, TNF-{alpha}, and proteasome contribute in the inhibition of fructose intestinal transport by sepsis in vivo

Lipopolysaccharide (LPS) endotoxin is a causative agent of sepsis. The aim of this study was to examine LPS effects on intestinal fructose absorption and to decipher mechanisms. Sepsis was induced by intravenous injection of LPS in rabbits. The ultrastructural study and DNA fragmentation patterns were identical in the intestine of LPS and sham animals. LPS treatment reduced fructose absorption altering both mucosal-to-serosal transepithelial fluxes and uptake into brush border membrane vesicles (BBMVs). Cytochalasin B was ineffective on fructose uptake, indicating that GLUT5, but not GLUT2, transport activity was targeted. GLUT5 protein levels in BBMvs were lower in LPS than in sham-injected rabbits. Thus lower fructose transport resulted from lower levels of GLUT5 protein. LPS treatment decreased GLUT5 levels by proteasome-dependent degradation. Specific inhibitors of PKC, PKA, and MAP kinases (p38MAPK, JNK, MEK1/2) protected fructose uptake from adverse LPS effect. Moreover, a TNF-alpha antagonist blocked LPS action on fructose uptake. We conclude that intestinal fructose transport inhibition by LPS is associated with diminished GLUT5 numbers in the brush border membrane of enterocytes triggered by activation of several interrelated signaling cascades and proteasome degradation.

Genetically based hypertension generated through interaction of mild hypoalphalipoproteinemia and mild hyperhomocysteinemia

BACKGROUND

Hyperhomocysteinemia and hypoalphalipoproteinemia are two well-reported risk factors for cardiovascular disease. The effects of the synergistic combination of these two factors on vascular function need to be investigated.

METHODS AND RESULTS

Four groups of male mice were used: a control wild-type group; a group of mice heterozygous for cystathionine beta-synthase deficiency; a group of mice heterozygous for apolipoprotein A-I deficiency; and, finally, a group of double heterozygous mice, with both cystathionine beta-synthase and apolipoprotein A-I deficiency. To characterize the resulting phenotype, several parameters including plasma apolipoproteins, lipid profiles, homocysteine, blood pressure and aortic protein were analyzed. As expected, our results indicate that double heterozygous mice are a model of mild hypoalphalipoproteinemia and hyperhomocysteinemia. Further, the additive combination of both risk factors resulted in a significant increase in blood pressure compared with control animals (136 +/- 8.0 versus 126 +/- 7.5 mm Hg, P < 0.01) that was not present in single heterozygous mice. The increase in blood pressure was associated with decreased plasma nitric oxide levels, left ventricle hypertrophy and was independent of low-density lipoprotein (LDL) cholesterol, para-oxonase activity and kidney histological changes. Concomitant decreases in levels of apolipoprotein A-IV (APOA-IV) and caveolin-1 content were also found in the double heterozygous group.

CONCLUSIONS

Our findings suggest an additive adverse effect of hypoalphalipoproteinemia and hyperhomocysteinemia on endothelial function to generate clinical hypertension and cardiac muscle hypertrophy mediated by dysregulation in nitric oxide metabolism.

Antiatherogenicity of extra virgin olive oil and its enrichment with green tea polyphenols in the atherosclerotic apolipoprotein-E-deficient mice: enhanced macrophage cholesterol efflux

The antiatherogenic properties of extra virgin olive oil (EVOO) enriched with green tea polyphenols (GTPPs; hereafter called EVOO-GTPP), in comparison to EVOO, were studied in the atherosclerotic apolipoprotein-E-deficient (E0) mice. E0 mice (eight mice in each group) consumed EVOO or EVOO-GTPP (7 microl/mouse/day, for 2 months) by gavage feeding. The placebo group received only water. At the end of the study, blood samples, peritoneal macrophages and aortas were collected. Consumption of EVOO or EVOO-GTPP resulted in a minimal increase in serum total and high-density lipoprotein (HDL) cholesterol levels (by 12%) and in serum paraoxonase 1 activity (by 6% and 10%). EVOO-GTPP (but not EVOO) decreased the susceptibility of the mouse serum to AAPH-induced lipid peroxidation (by 18%), as compared to the placebo-treated mice. The major effect of both EVOO and EVOO-GTPP consumption was on HDL-mediated macrophage cholesterol efflux. Consumption of EVOO stimulated cholesterol efflux rate from mouse peritoneal macrophages (MPMs) by 42%, while EVOO-GTPP increased it by as much as 139%, as compared to MPMs from placebo-treated mice. Finally, the atherosclerotic lesion size of mice was significantly reduced by 11% or 20%, after consumption of EVOO or EVOO-GTPP, respectively. We thus conclude that EVOO possesses beneficial antiatherogenic effects, and its enrichment with GTPPs further improved these effects, leading to the attenuation of atherosclerosis development.

Extra Virgin Olive Oils Increase Hepatic Fat Accumulation and Hepatic Antioxidant Protein Levels in APOE-/- Mice

We assessed the effects of Picual and Arbequina olive oil, rich and poor in polyphenols, respectively, on plasma lipid and glucose metabolism, hepatic fat content, and the hepatic proteome in female Apoe-/- mice. Both olive oils increased hepatic fat content and adipophilin levels (p < 0.05), though Picual olive oil significantly decreased plasma triglycerides (p < 0.05). Proteomics identified a range of hepatic antioxidant enzymes that were differentially regulated by both olive oils as compared with palm oil. We found a clear association between olive oil consumption and differential regulation of adipophilin and betaine homocysteine methyl transferase as modulators of hepatic triglyceride metabolism. Therefore, our "systems biology" approach revealed hitherto unrecognized insights into the triglyceride-lowering and anti-atherogenic mechanisms of extra virgin olive oils, wherein the up-regulation of a large array of anti-oxidant enzymes may offer sufficient protection against lesion development and diminish oxidative stress levels instigated by hepatic steatosis.

The results in rodent models of atherosclerosis are not interchangeable: the influence of diet and strain

The determinant factors for the development of atherosclerosis in response to dietary cholesterol were examined in two animal models to assess the comparability of results. We studied 128 male Apo E(-/-) and 128LDLr(-/-) mice randomly assigned to baseline (n=8) and 5 groups (n=24 each) that differed only in their dietary fat and cholesterol supplements. At 10, 16, 24 and 32 weeks of age, 8 animals from each group were sequentially sacrificed and the variables analyzed. The lesion sizes changed at different rates but they were predictable and did not differ in complexity. We observed, however, significant differences between strains, particularly in the constitutive expression of liver genes, their metabolic response to dietary cholesterol, their feeding behaviour, their glucose tolerance and the gain in body weight. Both strains presented characteristics that resemble steatohepatitis but manifestations were more severe in LDLr(-/-) mice. The divergent responses indicate that the choice of the diet and the model should be carefully considered in atherosclerosis studies and extrapolations interpreted with caution.

Intestinal d-Galactose Transport in an Endotoxemia Model in the Rabbit

Lipopolysaccharide (LPS) is an endotoxin causing sepsis. Studies from our laboratory revealed impaired intestinal absorption of L-leucine and D-fructose in LPS-treated rabbits. The aim of this study was to examine intestinal D-galactose transport following intravenous administration of LPS in the rabbit and to identify the cellular mechanisms driving this process. Endotoxin treatment diminished the buildup of D-galactose in intestinal tissue, the mucosal to serosal transepithelial flux of the sugar and its uptake by brush border membrane vesicles (BBMVs). Intracellular signaling pathways associated with protein kinase C (PKC), protein kinase A (PKA), p38 mitogen-activated protein kinase (p38MAPK), Jun N-terminal kinase (JNK), MAPK/extracellular signal-regulated kinases 1 and 2 (MEK1/2) and proteasome were found to be involved in this reduction in sugar uptake. Na(+)/glucose cotransporter 1 (SGLT1) protein levels in BBMVs were lower for LPS-treated animals than control animals. These findings indicate that LPS inhibits the intestinal absorption of D-galactose via a complex cellular mechanism that could involve posttranscriptional regulation of the SGLT1 transporter.

Olive oil preparation determines the atherosclerotic protection in apolipoprotein E knockout mice

Oils enriched in monounsaturated fatty acids do not seem to behave similarly in protecting against the development of atherosclerosis in animal models, which has been attributed to the presence of soluble phenolic compounds. To test the relevance of other components of oils in the prevention of atherosclerosis, two olive oils from the same cultivar devoid of soluble phenolic compounds were prepared using different procedures (pressure or centrifugation), characterized and fed to apolipoprotein E-deficient mice as 10% (w/w) of their diet. The 2 olive oils had similar levels of monounsaturated fatty acids and squalene, but they differed in their content of linoleic, phytosterols, tocopherols, triterpenes and waxes, which were particularly enriched in the test olive oil obtained by centrifugation. In mice that received a diet enriched in the olive oil derived through centrifugation, the progression of atherosclerosis was delayed compared to the mice that received standard olive oil. That effect was associated with decreases in plasma triglycerides, total and non-high-density lipoprotein cholesterol and isoprostane 8-iso-prostaglandin F(2alpha). Our results clearly indicate that the preparation of olive oil is crucial in determining its antiatherosclerotic effect, which extends beyond the presence of phenolic compounds. The test olive oil exerted its antiatherosclerotic effects by modifying plasma lipids and oxidative stress, and it might be a good candidate to replace other fats in functional foods.

Microarray analysis of hepatic genes differentially expressed in the presence of the unsaponifiable fraction of olive oil in apolipoprotein E-deficient mice

The hypothesis that the unsaponifiable fraction of olive oil dramatically influences hepatic gene expression was tested in mice. Two olive oils, obtained from the same olive cultivar but by different technological procedures, were characterized to show that they differed mainly in terms of the composition/quantity of this unsaponifiable fraction. Using DNA microarrays, hepatic gene expression was analysed in apoE-deficient mice fed one of two isoenergetic, isonitrogenous diets containing either 10 % (w/w) olive oil or unsaponifiable fraction-enriched olive oil. To provide an initial screening of potential candidate genes involved in a differential response, only genes with remarkably modified expression (signal log2ratio >3 or < − 3) were further considered. The eleven genes fulfilling these prerequisites were confirmed by quantitative RT–PCR, and then analysed in apoE-deficient mice with a C57BL/6J genetic background.Orosomucoidandserum amyloid A2were upregulated (to variable extents depending on the genetic background) in the absence of hepatic steatosis and inflammation.Fabp5andMt2were also strongly upregulated. Several proteases were highly suppressed by the unsaponifiable-enriched olive diet, independent of the genetic background. The findings indicate that change in the expression of these genes is a good marker of the intake of the unsaponifiable fraction of olive oil. The results highlight the important biological effects of the unsaponifiable fraction of olive oil. The term ‘monounsaturated fatty acid-enriched oil’ no longer appears appropriate for describing all the oils to which it is currently applied since it does not adequately reflect that they have different biological effects.

Response of ApoA-IV in pigs to long-term increased dietary oil intake and to the degree of unsaturation of the fatty acids

ApoA-IV is a protein constituent of HDL particles; the gene coding for it is a member of the ApoA-I–ApoC-III–ApoA-IV cluster. To investigate the effects of the quantity and the degree of saturation of dietary lipid on the long-term response of this Apo, and on the hypothetical coordinated regulation of the clusterin vivo, pigs were fed isoenergetic, cholesterol-free, low-lipid or lipid-enriched diets (containing either extra olive oil (rich in MUFA) or sunflower oil (rich inn−6 PUFA)) for 42 d. In animals fed on the control diet, ApoA-IV was mainly associated with plasma lipoproteins. An increase in plasma ApoA-IV concentration, mainly in the lipoprotein-free fraction, was induced by the lipid-enriched diets, independent of the degree of saturation of the fatty acids involved. The latter diets also led to increases in hepatic ApoA-I, ApoA-IV and ApoC-III mRNA levels, more so with the sunflower oil-rich diet. The present results show that porcine plasma ApoA-IV levels and their association with lipoproteins are very sensitive to increases in dietary lipids, independent of the degree of fatty acid saturation. Furthermore, hepatic expression of RNA appears to be coordinated along with that of the other members of the gene cluster.

Inhibitory effect of TNF-α on the intestinal absorption of galactose

Sepsis is a systemic response to infection in which toxins, such as bacterial lipopolysaccharide (LPS), stimulate the production of inflammatory mediators like the cytokine tumor necrosis factor alpha (TNF-alpha). Previous studies from our laboratory have revealed that LPS inhibits the intestinal absorption of L-leucine and D-fructose in rabbit when it was intravenously administered, and that TNF-alpha seems to mediate this effect on amino acid absorption. To extend this work, the present study was designed to evaluate the possible effect of TNF-alpha on D-galactose intestinal absorption, identify the intracellular mechanisms involved and establish whether this cytokine mediates possible LPS effects. Our findings indicate that TNF-alpha decreases D-galactose absorption both in rabbit intestinal tissue preparations and brush-border membrane vesicles. Western blot analysis revealed reduced amounts of the Na+/glucose cotransporter (SGLT1) protein in the plasma membrane attributable to the cytokine. On the contrary, TNF-alpha increased SGLT1 mRNA levels. Specific inhibitors of the secondary messengers PKC, PKA, the MAP kinases p38 MAP, JNK, MEK1/2 as well as the proteasome, diminished the TNF-alpha-evoked inhibitory effect. LPS inhibition of the uptake of the sugar was blocked by a TNF-alpha antagonist. In conclusion, TNF-alpha inhibits D-galactose intestinal absorption by decreasing the number of SGLT1 molecules at the enterocyte plasma membrane through a mechanism in which several protein-like kinases are involved.

Antiatherogenic effects of n-3 fatty acids - evidence and mechanisms

N-3 (omega-3) (polyunsaturated) fatty acids are thought to display a variety of beneficial effects for human health. Clues to the occurrence of cardiovascular protective effects have been, however, the spur for the first biomedical interest in these compounds, and are the best documented. Historically, the epidemiologic association between dietary consumption of n-3 fatty acids and cardiovascular protection was first suggested by Bang and Dyerberg, who identified the high consumption of fish, and therefore, of fish oil-derived n-3 fatty acids, as the likely explanation for the strikingly low rate of coronary heart disease events reported in the Inuit population. Since their initial reports, research has proceeded in parallel to provide further evidence for their cardioprotection and to understand underlying mechanisms. Decreased atherogenesis is currently thought to be a part of the cardiovascular protection by n-3 fatty acids. This article summarizes the evidence for such a claim and the mechanisms putatively involved.

Accelerated atherosclerosis in apolipoprotein E-deficient mice fed Western diets containing palm oil compared with extra virgin olive oils: a role for small, dense high-density lipoproteins

To test the hypothesis that extra virgin olive oils from different cultivars added to Western diets might behave differently than palm oil in the development of atherosclerosis, apoE-deficient mice were fed diets containing different cultivars of olive oil for 10 weeks. Female mice were assigned randomly to one of the following five groups: (1-4) fed chow diets supplemented with 0.15% (w/w) cholesterol and 20% (w/w) extra virgin olive oil from the Arbequina, Picual, Cornicabra, or Empeltre cultivars, and (5) fed a chow diet supplemented with 0.15% cholesterol and 20% palm oil. Compared to diets containing palm oil, a Western diet supplemented with one of several varieties of extra virgin olive oil decreased atherosclerosis lesions, reduced plaque size, and decreased macrophage recruitment. Unexpectedly, total plasma paraoxonase activity, apoA-I, plasma triglycerides, and cholesterol played minor roles in the regulation of differential aortic lesion development. Extra virgin olive oil induced a cholesterol-poor, apoA-IV-enriched lipoparticle that has enhanced arylesterase and antioxidant activities, which is closely associated with reductions in atherosclerotic lesions. Given the anti-atherogenic properties of extra virgin olive oil evident in animal models fed a Western diet, clinical trials are needed to establish whether these oils are a safe and effective means of treating atherosclerosis.

Folic acid supplementation delays atherosclerotic lesion development in apoE-deficient mice

Folic acid is a vitamin that when used as a dietary supplementation can improve endothelial function. To assess the effect of folic acid on the development of atherosclerosis, male apolipoprotein E-deficient mice fed a standard chow diet received either water (control group) or an aqueous solution of folic acid that provided a dose of 75 microg/kg/day, for ten weeks. At the time of sacrifice, blood was drawn and the heart removed. The study measured plasma homocysteine, lipids, lipoproteins, low-density lipoprotein (LDL) oxidation, isoprostane, paraoxonase, and apolipoproteins, and aortic atherosclerotic areas. In folic acid-treated animals, total cholesterol, mainly carried in very low-density and low-density lipoproteins, increased significantly, and homocysteine, HDL cholesterol, paraoxonase, and triglyceride levels did not change significantly. Plasma isoprostane and apolipoprotein (apo) B levels decreased. The resistance of LDL to oxidization and plasma apoA-I and apoA-IV levels increased with a concomitant decrease in the area of atherosclerotic lesions. The administration of folic acid decreased atherosclerotic lesions independently of plasma homocysteine and cholesterol levels, but was associated with plasma levels of apolipoproteins A-I, A-IV and B, and decreased oxidative stress.

Cystathionine β-synthase is essential for female reproductive function

In human reproduction, hyperhomocysteinemia has been reported as a risk factor for early pregnancy loss and congenital birth defects. Hyperhomocysteinemia is also recognized as a cause of maternal obstetric complications such as preeclampsia. The role of plasma hyperhomocysteinemia in female fertility was examined using cystathionine beta synthase knockout (cbs KO) mice. Cbs KO females were infertile, showed alterations in the estrus cycle and an increased progesterone response during pseudo-pregnancy induction. Both cbs KO ovaries and ovulated oocytes showed no major morphological alterations. However, placental and uterine masses were decreased at day 18 of pregnancy and showed morphological abnormalities. In cbs-KO pregnant females, the number of uterine implantation sites was not decreased despite the low number of surviving embryos. Fertility was restored when cbs-deficient ovaries were transplanted to normal ovarectomized recipients. We detected an increased uterine expression of Grp78, a marker of endoplasmic reticulum stress, which was accompanied by the decreased levels of uterine cbs mRNA in both hyperhomocysteinemic heterozygous (fertile) and homozygous (non-fertile) females. Our results indicate that cbs -/- female infertility is a consequence of the uterine failure and demonstrate that uterine endoplasmic reticulum stress and cbs expression are not determinant of infertility, suggesting that uterine dysfunction is a consequence of either hyperhomocysteinemia or other factor(s) in the uterine environment of cbs -/- animals. In summary, these studies demonstrate the potential importance of homocysteine levels for uterine handling of embryos.

Hydroxytyrosol administration enhances atherosclerotic lesion development in apo E deficient mice

Hydroxytyrosol is a phenol found in olive oil. To verify the effect of hydroxytyrosol on the development of atherosclerosis, two groups of apo E deficient male mice on a standard chow diet were used: the control group receiving only water, and the second group an aqueous solution of hydroxytyrosol in order to provide a dose of 10 mg/kg/day to each mouse. This treatment was maintained for 10 weeks. At the moment of sacrifice, blood was drawn and heart removed. Plasma lipids, apolipoproteins and monocyte Mac-1 expression were assayed as well as aortic atherosclerotic areas in both groups. Data showed no significant changes in HDL cholesterol, paraoxonase, apolipoprotein B or triglyceride levels. However, hydroxytyrosol administration decreased apolipoprotein A-I and increased total cholesterol, atherosclerotic lesion areas and circulating monocytes expressing Mac-1. The latter was highly correlated with lesion areas (r = 0.65, P < 0.01). These results indicate that administration of hydroxytyrosol in low cholesterol diets increases atherosclerotic lesion associated with the degree of monocyte activation and remodelling of plasma lipoproteins. Our data supports the concept that phenolic-enriched products, out of the original matrix, could be not only non useful but also harmful. Our results suggest that the formulation of possible functional foods should approximate as much as possible the natural environment in which active molecules are found.

Trans-10, cis-12- and cis-9, trans-11-conjugated linoleic acid isomers selectively modify HDL-apolipoprotein composition in apolipoprotein E knockout mice

Trans-10, cis-12-conjugated linoleic acid (CLA)-enriched diets promote atherosclerosis in mice despite increasing blood concentrations of HDL cholesterol. This suggests that under these conditions, the HDL apolipoproteins (apo) produced are abnormal. To test this hypothesis, apoE-deficient mice were fed a Western-type diet enriched with linoleic acid (control), cis-9, trans-11-CLA or trans-10, cis-12-CLA (1.0% wt/wt) for 12 wk, and the effects on HDL metabolism and apoC-III levels recorded. Compared with the control and cis-9, trans-11-CLA mice, those fed the trans-10, cis-12-CLA diet had significantly higher HDL cholesterol concentrations, and had a higher incidence of hypertriglyceridemia and hepatic steatosis. Plasma apoA-I and paraoxonase concentrations were significantly lower in the trans-10, cis-12-CLA group than in the cis-9, trans-11-CLA group. These reductions were associated with decreased hepatic expression of these proteins and a shift toward lipid-poor apolipoprotein particles. The plasma apoA-II concentration increased with its corresponding mRNA concentration in the liver, and was preferentially bound to HDL in the trans-10, cis-12-CLA mice, thus explaining the increased HDL cholesterol concentrations in this group. Significant, positive associations were found between apoA-II and C-III (r=0.883, P<0.001) and between apoA-II and atherosclerosis (r=0.68, P<0.001). These results indicate that trans-10, cis-12-CLA intake modifies HDL to form a proatherogenic apoA-II containing particle and promotes phenotypic changes compatible with metabolic syndrome. Cis-9, trans-11-CLA does not promote this detrimental effect.

Linoleic acid-rich fats reduce atherosclerosis development beyond its oxidative and inflammatory stress-increasing effect in apolipoprotein E-deficient mice in comparison with saturated fatty acid-rich fats

The relative benefit of replacing saturated fatty acid with linoleic acids is still being debated because a linoleic acid-enriched diet increases oxidative and inflammatory stresses, although it is associated with a reduction in serum cholesterol levels. The present study was conducted to evaluate the effect of dietary supplementation of linoleic acid-rich (HL) fat, compared with a saturated fatty acid-rich (SF) fat on atherosclerotic lesion areas, serum and liver cholesterol levels, oxidative stress (urinary isoprostanes and serum malondialdehayde) and inflammatory stress (expression of aortic monocyte chemoattractant protein-1; MCP-1) in apo E-deficient mice. Male and female apo E-deficient mice (8 weeks old; seven to eight per group) were fed an AIN-76-based diet containing SF fat (50 g palm oil and 50 g lard/kg) or HL fat (100 g high-linoleic safflower-seed oil/kg) for 9 weeks. Compared with the SF diet, the HL diet lowered atherosclerosis (P<0.05). It reduced serum total cholesterol levels (P<0.05), increased HDL-cholesterol levels (P<0.05) and lowered liver esterified cholesterol levels (P<0.01). The HL diet-fed mice showed increased expression of MCP-1 mRNA (P<0.05), serum levels of malondialdehayde (P<0.05) and urinary excretion of 2,3-dinor-5,6-dihydro-8-iso-prostaglandin F2alpha; P<0.05). These results suggest that having biomarkers in vivo for oxidative stress and inflammatory status of endothelial cells does not necessarily indicate predisposition to an increased lesion area in the aortic root in apo E-deficient mice fed an HL or SF diet.