Cholesterol modulates LRP5 expression in the vessel wall.

OBJECTIVE: Macrophages are key players in atherosclerotic lesion formation and progression. We have recently demonstrated that lipid-loaded macrophages show activation of the canonical Wnt signaling pathway. METHODS: To test the in vivo role of the canonical Wnt pathway in atherosclerosis we used mice deficient in the Wnt signaling receptor LRP5 (LRP5(-/-)) fed a hypercholesterolemic diet (HC) to induce atherosclerosis. These dietary groups were further subdivided into two subgroups receiving their respective diets supplemented with 2% plant sterol esters (PSE). All mice remained on their assigned diets until age 18 weeks. RESULTS: HC WT mice had mildly increased non-HDL cholesterol levels, developed aortic atherosclerotic lesions and showed upregulated expression levels of aortic Lrp5. HC LRP5(-/-) mice develop larger aortic atherosclerotic lesions than WT mice indicating that LRP5 has a protective function in atherosclerosis progression. The oral administration of PSE, a dietary cholesterol-lowering agent, had an effect in the expression levels of the Wnt signaling receptor and in atherosclerosis progression. We found that PSE reduced serum total cholesterol levels, abolished HC-induced LRP5 overexpression and reduced aortic atherosclerotic plaques. CONCLUSION: The proatherogenic effects of the excess of plasma lipids are in part mediated by modulation of LRP5 in the aorta. LRP5 and canonical Wnt signaling exert a protective defense mechanism against hyperlipidemia and atherosclerosis lesion progression.

Olive oil and health: summary of the II international conference on olive oil and health consensus report, Jaén and Córdoba (Spain) 2008.

Olive oil (OO) is the most representative food of the traditional Mediterranean Diet (MedDiet). Increasing evidence suggests that monounsaturated fatty acids (MUFA) as a nutrient, OO as a food, and the MedDiet as a food pattern are associated with a decreased risk of cardiovascular disease, obesity, metabolic syndrome, type 2 diabetes and hypertension. A MedDiet rich in OO and OO per se has been shown to improve cardiovascular risk factors, such as lipid profiles, blood pressure, postprandial hyperlipidemia, endothelial dysfunction, oxidative stress, and antithrombotic profiles. Some of these beneficial effects can be attributed to the OO minor components. Therefore, the definition of the MedDiet should include OO. Phenolic compounds in OO have shown antioxidant and anti-inflammatory properties, prevent lipoperoxidation, induce favorable changes of lipid profile, improve endothelial function, and disclose antithrombotic properties. Observational studies from Mediterranean cohorts have suggested that dietary MUFA may be protective against age-related cognitive decline and Alzheimer's disease. Recent studies consistently support the concept that the OO-rich MedDiet is compatible with healthier aging and increased longevity. In countries where the population adheres to the MedDiet, such as Spain, Greece and Italy, and OO is the principal source of fat, rates of cancer incidence are lower than in northern European countries. Experimental and human cellular studies have provided new evidence on the potential protective effect of OO on cancer. Furthermore, results of case-control and cohort studies suggest that MUFA intake including OO is associated with a reduction in cancer risk (mainly breast, colorectal and prostate cancers).

International conference on the healthy effect of virgin olive oil.

1. Ageing represents a great concern in developed countries because the number of people involved and the pathologies related with it, like atherosclerosis, morbus Parkinson, Alzheimer's disease, vascular dementia, cognitive decline, diabetes and cancer. 2. Epidemiological studies suggest that a Mediterranean diet (which is rich in virgin olive oil) decreases the risk of cardiovascular disease. 3. The Mediterranean diet, rich in virgin olive oil, improves the major risk factors for cardiovascular disease, such as the lipoprotein profile, blood pressure, glucose metabolism and antithrombotic profile. Endothelial function, inflammation and oxidative stress are also positively modulated. Some of these effects are attributed to minor components of virgin olive oil. Therefore, the definition of the Mediterranean diet should include virgin olive oil. 4. Different observational studies conducted in humans have shown that the intake of monounsaturated fat may be protective against age-related cognitive decline and Alzheimer's disease. 5. Microconstituents from virgin olive oil are bioavailable in humans and have shown antioxidant properties and capacity to improve endothelial function. Furthermore they are also able to modify the haemostasis, showing antithrombotic properties. 6. In countries where the populations fulfilled a typical Mediterranean diet, such as Spain, Greece and Italy, where virgin olive oil is the principal source of fat, cancer incidence rates are lower than in northern European countries. 7. The protective effect of virgin olive oil can be most important in the first decades of life, which suggests that the dietetic benefit of virgin olive oil intake should be initiated before puberty, and maintained through life. 8. The more recent studies consistently support that the Mediterranean diet, based in virgin olive oil, is compatible with a healthier ageing and increased longevity. However, despite the significant advances of the recent years, the final proof about the specific mechanisms and contributing role of the different components of virgin olive oil to its beneficial effects requires further investigations.

Effects of dietary fatty acids and vitamin E levels in HL-60 cell proliferation.

BACKGROUND: Fatty acids have shown to be both modulators and messengers of signals triggered at the level of cell membranes. There is, however, controversy about the role of fatty acids in cell proliferation kinetics, and it is still unknown whether cell proliferation can be regulated by fatty acid dietary intake in humans. Our objective was to investigate whether feasible changes in the human dietary food intake that induce significant changes in lipids, fatty acids and the oxidative state were able to influence proliferation kinetics of the leukaemia cell line HL-60. MATERIALS AND METHODS: Healthy men and women were subjected to four consecutive dietary periods with increasing degree of unsaturation: saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), n-6 polyunsaturated fatty acids (n-6 PUFAs), n-3 polyunsaturated fatty acids (n-3 PUFAs). Plasma lipids and oxidation parameters were controlled during each period. Serum from each subject in the four dietary periods was incubated for 3 days with the leukaemia cell line, HL-60 (250 x 10(3) cell mL-1), to study cell proliferation. RESULTS: In men, an n-3 polyunsaturated fatty acid-enriched diet showed a significant inhibition of DNA duplication with respect to a saturated-enriched diet, but the effect is not sufficient in blocking cell proliferation. However, as expected, the in vitro addition of fatty acids to HL-60 cells significantly halted proliferation. In addition, the HL-60 growth ratio was shown to be inversely correlated with plasma vitamin E (P = 0.0004) and oleic acid in phospholipids (P = 0.01) in plasma of the individuals in the dietary intervention study. CONCLUSIONS: Our results demonstrate that changes in serum fatty acid composition obtained with dietary changes, without extreme variations of the regular diets of a free-living population, cannot block HL-60 cell proliferation.

Dissolution of mural thrombus by specific thrombin inhibition with r-hirudin: comparison with heparin and aspirin.

BACKGROUND: The presence of residual mural thrombus may predispose to recurrent thrombotic events in acute coronary syndromes. The purpose of this study was to evaluate the effects of antithrombotic and antiplatelet agents on a preformed, fresh mural thrombus during growth of thrombus. METHODS AND RESULTS: A fresh mural thrombus was formed by perfusing severely injured arterial wall with porcine blood for 5 minutes at a shear rate of 1690 s(-1). Thrombus formation was measured by morphometric analysis (mm2/mm). The average size of a mural thrombus formed in 5 minutes was 0.14+/-0.03 mm2/mm. Progression of thrombus growth within 10 minutes triggered by the preformed thrombus was evaluated in pigs treated with r-hirudin (1 mg/kg per hour i.v.) as a probe for thrombin, high-dose heparin (250 IU/kg per hour i.v.), moderate-dose heparin (100 IU/kg per hour), moderate-dose heparin (100 IU/kg per hour) plus aspirin, aspirin alone (5 mg/kg i.v.), and placebo. Hirudin was associated with a significant decrease (48%) of mural thrombus area and significantly reduced growth of thrombus (0.07+/-0.01), even compared with the highest dose of heparin (0.15+/-0.03), although at lower levels of anticoagulation. Inhibition of growth of thrombus with heparin was dose dependent, showing an inverse correlation of thrombus area with mean plasma heparin concentrations (r=.77, P=.0001). Thrombus size was unchanged by aspirin (0.29+/-0.07) compared with controls (0.28+/-0.07). CONCLUSIONS: Direct inhibition of thrombin activity with r-hirudin completely inhibits growth of thrombus, causes dissolution of a preexisting mural thrombus, and is more effective at lower levels of anticoagulation than the highest dose of heparin at shear rates typical of a moderate coronary stenosis.

A garlic derivative, ajoene, inhibits platelet deposition on severely damaged vessel wall in an in vivo porcine experimental model.

Ajoene, (E,Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide, is a potent antiplatelet compound isolated from alcoholic extracts of garlic. In vitro, ajoene reversibly inhibits platelet aggregation as well as the release reaction induced by all known agonists. We used a well characterized perfusion chamber to study the in vivo effects of ajoene on platelet deposition onto a highly thrombogenic, severely damaged arterial wall, obtained by stripping off the intimal layer and exposing tunica media. Platelet-vessel wall interaction and the effect of ajoene was studied under flow conditions of high and low local shear rate that mimics laminar blood flow in small and medium size arteries (1690 sec-1 and 212 sec-1). Our results indicate that administration of ajoene to heparinized animals, significantly prevents thrombus formation at local low blood shear rate. Ajoene does not inhibit binding of vWF to GPIb, therefore, it does not affect platelet adhesion. In fact, although ajoene impairs fibrinogen and vWF (less efficient) binding to GPlIb/IIIa, it does not totally inhibits platelet deposition to the substrates at any of the shear rates used in this study. Our present results, under in vivo flow conditions and in the presence of physiological calcium levels, suggest that ajoene may be potentially useful for the acute prevention of thrombus formation induced by severe vascular damage, mainly in arterial sites with local low shear rates.

Effect of ajoene, the major antiplatelet compound from garlic, on platelet thrombus formation.

Ajoene, (E,Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide, is a potent antiplatelet compound isolated from alcoholic extracts of garlic (Allium sativum). Ajoene reversibly inhibits in vitro platelet aggregation as well as release reaction induced by all known agonists. We used a well characterized cylindrical perfusion chamber to study the effect of ajoene on platelet deposition onto physiological substrates such as pig aortic subendothelium and tunica media as a model of mildly and severely damaged vessel wall respectively. Experiments were performed under flow conditions of high and low shear rate that mimic laminar blood flow in small and medium size arteries (1690 sec-1 and 212 sec-1). Our results indicate that ajoene prevents thrombus formation both at low and high shear rate in citrated whole blood. The inhibitory effect of ajoene on platelet-thrombus formation seems to be dependent on its inhibition of fibrinogen binding, since significantly higher concentrations of ajoene are needed to affect von Willebrand factor binding to GPIIb/IIIa receptors. Further, ajoene does not impair Ristocetin-induced platelet agglutination, mediated by GPIb. Our results suggest that ajoene may be useful for the acute prevention of thrombus formation induced by vascular damage.

Dehydroepiandrosterone feeding prevents aortic fatty streak formation and cholesterol accumulation in cholesterol-fed rabbit.

The concentration of dehydroepiandrosterone sulfate (DHEA-S) in human plasma is higher than any other steroid. Recent evidence has suggested an inverse relationship between plasma DHEA levels and the development of coronary atherosclerosis in humans. We used the cholesterol-fed rabbit model to investigate whether DHEA feeding would diminish aortic fatty streak formation in this model. Fifteen New Zealand White rabbits were fed rabbit chow supplemented with 0.5% cholesterol (wt/wt). Seven animals were, in addition, fed DHEA, 0.5% of diet (wt/wt). Animals were sacrificed after 2 months, and the aortic involvement with fatty streaks was evaluated by computerized planimetry of Sudan IV-stained aortas and by chemical analysis of aortic wall lipids. Compared to controls, DHEA-fed animals had similar plasma levels of total, very low density lipoprotein (VLDL), low density lipoprotein (LDL), and high density lipoprotein (HDL) cholesterol, corticoids, and estrogens. DHEA-fed animals had higher plasma levels of total, VLDL, and LDL triglycerides and lower HDL triglycerides than did controls. DHEA feeding resulted in 30% and 40%, respectively, inhibition of fatty streak formation by chemical analysis and planimetry. We conclude that DHEA feeding inhibits the development of aortic fatty streaks in cholesterol-fed rabbits, independent of changes in plasma total and LDL cholesterol levels of DHEA conversion to estrogens or corticoids.