Scand Cardiovasc J. 2013 Dec;47(6):377-82.
Effects of trans fats on prostacyclin production.
Department of Comparative Biosciences, Burnsides Research Laboratory, College of Veterinary Medicine, University of Illinois, Urbana, IL , USA.
ABSTRACT: Prostacyclin is a prostanoid derived from arachidonic acid that prevents thrombosis and is thereby expected to protect against heart disease, while trans fats present in partially hydrogenated oils interfere with arachidonic acid metabolism. Therefore, the objective of the present study was to investigate how fats with different proportions of linoleic acid and trans-18:1 affect prostacyclin released by cultured endothelial cells, and to compare these proportions with those found in commercially available foods.
DESIGN: Soybean oil and hydrogenated soybean oil (coating fat) were mixed in different proportions to yield seven fat mixtures with proportions of linoleic acid ranging from 54.1% to 5.7% and trans-18:1 acid ranging from 0.4% to 43.9%. Human endothelial cells were cultured in each of the mixtures, and their phospholipid fractions were then separated and their fatty acids were analyzed by gas chromatography. The prostacyclin released by the cells was measured using RIA kits. Margarines and processed foods were purchased from the supermarket for comparison.
RESULTS: Our work revealed that as the percentage of trans fat was increased, the amount of prostacyclin released dose-dependently and significantly (P < 0.0001) decreased, the concentration of linoleic and arachidonic acid decreased in the membrane phospholipids while the concentration of trans 18:1 acids increased, the prostacyclin decreased by 35-98%. Supermarket margarines had levels of trans fats similar to those that suppressed prostacyclin by 35-54%. Most processed foods labeled as trans-free contained trans fats.
CONCLUSIONS: Trans fatty acids suppress prostacyclin production at levels found in commercial margarines, and processed foods labeled as trans-free could contribute to this effect if consumed in multiple servings or in addition to foods containing larger amounts of trans fats.
Atherosclerosis. 2013 Dec;231(2):456-61.
Gut microbiota metabolism of l-carnitine and cardiovascular risk.
Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, 5-1001-DD, 25 Orde Street, Toronto, Ontario M5T 3H7, Canada.
ABSTRACT: In recent years, a number of studies have alluded to the importance of the intestinal microflora in controlling whole-body metabolic homeostasis and organ physiology. In particular, it has been suggested that the hepatic production of trimethylamine-N-oxide (TMAO) from gut microbiota-derived trimethylamine (TMA) may enhance cardiovascular risk via promoting atherosclerotic lesion development. The source of TMA production via the gut microbiota appears to originate from 2 principle sources, either phosphatidylcholine/choline and/or l-carnitine. Therefore, it has been postulated that consumption of these dietary sources, which are often found in large quantities in red meats, may be critical factors promoting cardiovascular risk. In contrast, a number of studies demonstrate beneficial properties for l-carnitine consumption against metabolic diseases including skeletal muscle insulin resistance and ischemic heart disease. Furthermore, fish are a significant source of TMAO, but dietary fish consumption and fish oil supplementation may exhibit positive effects on cardiovascular health. In this mini-review we will discuss the discrepancies regarding l-carnitine supplementation and its possible negative effects on cardiovascular risk through potential increases in TMAO production, as well as its positive effects on metabolic health via increasing glucose metabolism in the muscle and heart.
ISRN Inflamm. 2013 May 12;2013:191823.
Atherosclerosis, Dyslipidemia, and Inflammation: The Significant Role of Polyunsaturated Fatty Acids.
Department of Laboratory Medicine, “Tor Vergata” University Hospital, Viale Oxford 81, 00133 Rome, Italy.
ABSTRACT: Phospholipids play an essential role in cell membrane structure and function. The length and number of double bonds of fatty acids in membrane phospholipids are main determinants of fluidity, transport systems, activity of membrane-bound enzymes, and susceptibility to lipid peroxidation. The fatty acid profile of serum lipids, especially the phospholipids, reflects the fatty acid composition of cell membranes. Moreover, long-chain n-3 polyunsatured fatty acids decrease very-low-density lipoprotein assembly and secretion reducing triacylglycerol production. N-6 and n-3 polyunsatured fatty acids are the precursors of signalling molecules, termed “eicosanoids,” which play an important role in the regulation of inflammation. Eicosanoids derived from n-6 polyunsatured fatty acids have proinflammatory actions, while eicosanoids derived from n-3 polyunsatured fatty acids have anti-inflammatory ones. Previous studies showed that inflammation contributes to both the onset and progression of atherosclerosis: actually, atherosclerosis is predominantly a chronic low-grade inflammatory disease of the vessel wall. Several studies suggested the relationship between long-chain n-3 polyunsaturated fatty acids and inflammation, showing that fatty acids may decrease endothelial activation and affect eicosanoid metabolism.
J Lipid Res. 2012 Jul;53(7):1348-58.
The role of oxysterols in control of endothelial stiffness.
Pulmonary, Critical Care, and Sleep Medicine, University of Illinois, Chicago, IL 60612, USA.
ABSTRACT: Endothelial dysfunction is a key step in atherosclerosis development. Our recent studies suggested that oxLDL-induced increase in endothelial stiffness plays a major role in dyslipidemia-induced endothelial dysfunction. In this study, we identify oxysterols, as the major component of oxLDL, responsible for the increase in endothelial stiffness. Using Atomic Force Microscopy to measure endothelial elastic modulus, we show that endothelial stiffness increases with progressive oxidation of LDL and that the two lipid fractions that contribute to endothelial stiffening are oxysterols and oxidized phosphatidylcholines, with oxysterols having the dominant effect. Furthermore, endothelial elastic modulus increases as a linear function of oxysterol content of oxLDL. Specific oxysterols, however, have differential effects on endothelial stiffness with 7-ketocholesterol and 7α-hydroxycholesterol, the two major oxysterols in oxLDL, having the strongest effects. 27-hydroxycholesterol, found in atherosclerotic lesions, also induces endothelial stiffening. For all oxysterols, endothelial stiffening is reversible by enriching the cells with cholesterol. oxLDL-induced stiffening is accompanied by incorporation of oxysterols into endothelial cells. We find significant accumulation of three oxysterols, 7α-hydroxycholesterol, 7β-hydroxycholesterol, and 7-ketocholesterol, in mouse aortas of dyslipidemic ApoE⁻/⁻ mice at the early stage of atherosclerosis. Remarkably, these are the same oxysterols we have identified to induce endothelial stiffening.
Cardiol Res Pract. 2011;2011:386892.
Cardiovascular disease-related lifestyle factors and longevity.
First Cardiology Clinic, School of Medicine, National and Kapodistrian, University of Athens, 11528 Athens, Greece.
Doctors Reverse Advice on Cholesterol and Heart Disease 2011
Without inflammation, cholesterol won’t accumulate in blood vessel walls and cause heart disease
Heart Surgeon Admits Huge Mistake! We physicians with all our training, knowledge and authority often acquire a rather large ego that tends to make it difficult to admit we are wrong. So, here it is. I freely admit to being wrong. As a heart surgeon with 25 years experience, having performed over 5,000 open-heart surgeries, today is my day to right the wrong with medical and scientific fact. I trained for many years with other prominent physicians labeled “opinion makers.” Bombarded with scientific literature, continually attending education seminars, we opinion makers insisted heart disease resulted from the simple fact of elevated blood cholesterol.
The only accepted therapy was prescribing medications to lower cholesterol and a diet that severely restricted fat intake. The latter of course we insisted would lower cholesterol and heart disease.
Deviations from these recommendations were considered heresy and could quite possibly result in malpractice. It Is Not Working! These recommendations are no longer scientifically or morally defensible. The discovery a few years ago that inflammation in the artery wall is the real cause of heart disease is slowly leading to a paradigm shift in how heart disease and other chronic ailments will be treated.
Am J Clin Nutr. 2010 Jul;92(1):186-93.
Fatty acids in serum phospholipids and carotid intima-media thickness in Spanish subjects with primary dyslipidemia.
Unitat de Lípids, Sunyer Hospital Clínic, Barcelona, Spain.
BACKGROUND: Low rates of incident ischemic heart disease (IHD) and cardiac death occur in Spain despite a high prevalence of cardiovascular risk factors. High consumption of unsaturated fatty acid-rich foods, such as olive oil, nuts, and seafood, might underlie this paradox.
OBJECTIVE: We investigated whether serum phosphatidylcholine enrichment in oleic, linoleic, alpha-linolenic, and n-3 (omega-3) long-chain polyunsaturated fatty acids (as biomarkers of olive oil, seed oil, walnut, and fish intake, respectively) relate to carotid atherosclerosis in Spanish subjects at risk of IHD.
DESIGN: In a cross-sectional study, we measured fatty acid concentrations in serum phosphatidylcholine and measured carotid intima-media thickness (IMT) by using ultrasound in 451 asymptomatic subjects (261 men, 190 women; mean age: 45 y) with primary dyslipidemia. Main and secondary outcomes were mean and maximum IMT in the common carotid artery (CCA) and other carotid segments, respectively.
RESULTS: Phosphatidylcholine fatty acid composition was similar to that reported for other Spanish populations. Multiple regression analyses showed that proportions of oleic and docosahexaenoic acids were inversely related to mean CCA IMT (P < 0.02, all) after adjustment for several confounders. In similar models, alpha-linolenic acid related inversely to mean and maximum internal carotid artery IMT (P < 0.05 for all). Linoleic and eicosapentaenoic acids were unrelated to IMT.
CONCLUSIONS: Higher phospholipid proportions of oleic, alpha-linolenic, and docosahexaenoic acids showed inverse associations with IMT at specific carotid segments in subjects with primary dyslipidemia. High intakes of healthy fats might explain, in part, the Spanish paradox of low IHD rates in the face of a high burden of cardiovascular risk factors.
Lipids Health Dis. 2010 Nov 9;9:130
A defect in Δ6 and Δ5 desaturases may be a factor in the initiation and progression of insulin resistance, the metabolic syndrome and ischemic heart disease in South Asians.
UND Life Sciences, 13800 Fairhill Road, #321, Shaker Heights, OH 44120, USA. [email protected]
ABSTRACT: The high incidence of insulin resistance and the metabolic syndrome in South Asians remains unexplained. I propose that a defect in the activity of Δ⁶ and Δ⁵ desaturases and consequent low plasma and tissue concentrations of polyunsaturated fatty acids such as γ-linolenic acid (GLA), dihomo-γ-linolenic acid (DGLA), arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and formation of their anti-inflammatory products prostaglandin E₁ (PGE₁), prostacyclin (PGI₂), PGI₃, lipoxins, resolvins, protectins, maresins and nitrolipids could be responsible for the high incidence of insulin resistance, the metabolic syndrome and ischemic heart disease (IHD) in South Asians. This proposal is supported by the observation that South Asian Indians have lower plasma and tissue concentrations of GLA, DGLA, AA, EPA and DHA, the precursors of PGE₁, PGI₂, PGI₃, lipoxins, resolvins, protectins, and nitrolipids, the endogenous molecules that prevent platelet aggregation, vasoconstriction, thrombus formation, leukocyte activation and possess anti-inflammatory action and thus, are capable of preventing the development of insulin resistance, atherosclerosis, hypertension, type 2 diabetes mellitus and premature ischemic heart disease. Genetic predisposition, high carbohydrate intake, lack of exercise, tobacco use and low birth weight due to maternal malnutrition suppress the activity of Δ⁶ and Δ⁵ desaturases that leads to low plasma and tissue concentrations of polyunsaturated fatty acids and their products. This implies that adequate provision of polyunsaturated fatty acids and co-factors needed for their metabolism, and efforts to enhance the formation of their beneficial metabolites PGE₁, PGI₂, PGI₃, lipoxins, resolvins, protectins, maresins and nitrolipids could form a novel approach in the prevention and management of these diseases in this high-risk population.
Curr Atheroscler Rep. 2010 Nov;12(6):391-6.
Dietary monounsaturated fatty acids appear not to provide cardioprotection.
Department of Translational Pharmacology, Consorzio Mario Negri Sud, via Nazionale 8/A, 66030, S. Maria Imbaro, CH, Italy.
ABSTRACT: Dietary interventions have been consistently proposed as a part of a comprehensive strategy to lower the incidence and severity of coronary heart disease (CHD), in the process providing long-term cardioprotection. Replacement of dietary saturated fatty acids (SFA) with higher intakes of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) has been reported to be inversely associated with risk of CHD. The observed lower incidence of CHD among populations consuming a Mediterranean-type diet, mainly enriched in MUFA from olive oil, has long supported the belief that MUFA are an optimal substitution for SFA. However, both epidemiologic and interventional studies suggest that although substituting MUFA-rich foods for SFA-rich foods in the diet can potentially lower total plasma cholesterol concentrations, this substitution does not lower the extent of coronary artery atherosclerosis. In addition, although recent evidence suggests that the source of MUFA (animal fat vs vegetable oils) may differentially influence the correlation between MUFA intake and CHD mortality, animal studies suggest that neither source is cardioprotective.
Nutrients. 2010 Feb;2(2):116-27.
Dietary phospholipids and intestinal cholesterol absorption.
Nutrition and Metabolism Group, Heart Research Institute, 7 Eliza St. Newtown 2042 NSW, Sydney, Australia. [email protected]
ABSTRACT: Experiments carried out with cultured cells and in experimental animals have consistently shown that phospholipids (PLs) can inhibit intestinal cholesterol absorption. Limited evidence from clinical studies suggests that dietary PL supplementation has a similar effect in man. A number of biological mechanisms have been proposed in order to explain how PL in the gut lumen is able to affect cholesterol uptake by the gut mucosa. Further research is however required to establish whether the ability of PLs to inhibit cholesterol absorption is of therapeutic benefit.
Int J Biol Sci. 2009 Jun 29;5(5):474-88.
Lipoproteins, cholesterol homeostasis and cardiac health.
Department of Animal Sciences, Washington State University, Pullman, WA 99164-6351, USA.
ABSTRACT: Cholesterol is an essential substance involved in many functions, such as maintaining cell membranes, manufacturing vitamin D on surface of the skin, producing hormones, and possibly helping cell connections in the brain. When cholesterol levels rise in the blood, they can, however, have dangerous consequences. In particular, cholesterol has generated considerable notoriety for its causative role in atherosclerosis, the leading cause of death in developed countries around the world. Homeostasis of cholesterol is centered on the metabolism of lipoproteins, which mediate transport of the lipid to and from tissues. As a synopsis of the major events and proteins that manage lipoprotein homeostasis, this review contributes to the substantial attention that has recently been directed to this area. Despite intense scrutiny, the majority of phenotypic variation in total cholesterol and related traits eludes explanation by current genetic knowledge. This is somewhat disappointing considering heritability estimates have established these traits as highly genetic. Thus, the continued search for candidate genes, mutations, and mechanisms is vital to our understanding of heart disease at the molecular level. Furthermore, as marker development continues to predict risk of vascular illness, this knowledge has the potential to revolutionize treatment of this leading human disease.
Lipids Health Dis. 2008 Oct 15;7:37.
Essential fatty acids and their metabolites could function as endogenous HMG-CoA eductase and ACE enzyme inhibitors, anti-arrhythmic, anti-hypertensive, anti-atherosclerotic, anti-inflammatory, cytoprotective, and cardioprotective molecules.
UND Life Sciences, 13800 Fairhill Road, #321, Shaker Heights, OH 44120, USA. [email protected]
ABSTRACT: Lowering plasma low density lipoprotein-cholesterol (LDL-C), blood pressure, homocysteine, and preventing platelet aggregation using a combination of a statin, three blood pressure lowering drugs such as a thiazide, a beta blocker, and an angiotensin converting enzyme (ACE) inhibitor each at half standard dose; folic acid; and aspirin-called as polypill- was estimated to reduce cardiovascular events by approximately 80%. Essential fatty acids (EFAs) and their long-chain metabolites: gamma-linolenic acid (GLA), dihomo-GLA (DGLA), arachidonic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) and other products such as prostaglandins E1 (PGE1), prostacyclin (PGI2), PGI3, lipoxins (LXs), resolvins, protectins including neuroprotectin D1 (NPD1) prevent platelet aggregation, lower blood pressure, have anti-arrhythmic action, reduce LDL-C, ameliorate the adverse actions of homocysteine, show anti-inflammatory actions, activate telomerase, and have cytoprotective properties. Thus, EFAs and their metabolites show all the classic actions expected of the “polypill”. Unlike the proposed “polypill”, EFAs are endogenous molecules present in almost all tissues, have no significant or few side effects, can be taken orally for long periods of time even by pregnant women, lactating mothers, and infants, children, and adults; and have been known to reduce the incidence cardiovascular diseases including stroke. In addition, various EFAs and their long-chain metabolites not only enhance nitric oxide generation but also react with nitric oxide to yield their respective nitroalkene derivatives that produce vascular relaxation, inhibit neutrophil degranulation and superoxide formation, inhibit platelet activation, and possess PPAR-gamma ligand activity and release NO, thus prevent platelet aggregation, thrombus formation, atherosclerosis, and cardiovascular diseases. Based on these evidences, I propose that a rational combination of omega-3 and omega-6 fatty acids and the co-factors that are necessary for their appropriate action/metabolism is as beneficial as that of the combined use of a statin, thiazide, a beta blocker, and an angiotensin converting enzyme (ACE) inhibitor, folic acid, and aspirin. Furthermore, appropriate combination of omega-3 and omega-6 fatty acids may even show additional benefits in the form of protection from depression, schizophrenia, Alzheimer’s disease, and enhances cognitive function; and serve as endogenous anti-inflammatory molecules; and could be administered from childhood for life long.
Atherosclerosis. 2009 Aug;205(2):404-12.
Soy phosphatidylcholine inhibited TLR4-mdiated MCP-1 expression in vascular cells.
Department of Medicine, Shiga University of Medical Science, Japan.
ABSTRACT: Inflammatory signaling via Toll-like receptor 4 (TLR4) has been shown to facilitate atherogenesis. Recent lines of evidence show that saturated fatty acids (SFAs) induce the inflammatory response via the TLR4 pathway in macrophages and adipocytes. The aims of this study are to confirm the role of SFAs in TLR4-mediated inflammatory signaling in vascular cells and to propose soy phosphatidylcholine (SPC) as an effective inhibitor against TLR4-mediated agonists. SFAs such as palmitate and stearate increased the expression and secretion of MCP-1 in human umbilical vein endothelial cells (HUVECs) and rat vascular smooth muscle cells (VSMCs). SFAs up-regulated the activity of MCP-1 promoter through the activation of NF-kappaB. Knockdown of TLR4 using siRNA diminished the SFA-induced MCP-1 expression in HUVECs and rat VSMCs, while PKC or ceramide signal inhibitor did not inhibit the expression. Furthermore, we found that SPC effectively inhibited the MCP-1 expression induced by palmitate or LPS in a dose-dependent manner. However, SPC did not inhibit the mRNA expression of MCP-1 induced by cytokines such as TNF-alpha and IL-1beta, or by agonists binding to TLRs other than TLR4. In addition, SPC did not affect the activity of LPS assessed by clotting activity of the Limulus amoebocyte lysate. These results clearly show that SPC specifically inhibits the inflammatory responses induced by the TLR4-dependent signal. In conclusion, we have demonstrated a role of SFAs for inflammatory response via TLR4-NF-kappaB signaling in vascular cells. Moreover, we propose that SPC can be useful as a selective inhibitor to suppress the TLR4-mediated inflammatory signaling.
Prostaglandins Leukot Essen Fatty Acids 2007;76:251-268 Lipids Health Dis. 2008 May 20;7:19.
Can endogenous lipid molecules serve as predictors and prognostic markers of coronary heart disease?
UND Life Sciences, 13800 Fairhill Road, #321, Shaker Heights, OH 44120, USA. [email protected]
ABSTRACT: Dyslipidemia, and inflammatory markers: high-sensitivity C-reactive protein (hs-CRP), myeloperoxidase (MPO), lipoprotein associated phospholipase A2(Lp-PLA2), and lipid peroxides (LP) are insufficient to predict the onset, extent, and prognosis of CHD. Lipoxins (LXs), resolvins, and protectins are derived from omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and omega-6 arachidonic acid in the presence of aspirin; whereas nitrolipids are formed due to the interaction between polyunsaturated fatty acids and nitric oxide (NO). LXs, resolvins, protectins, and nitrolipids are endogenous anti-inflammatory lipid molecules that inhibit production of interleukin-6 (IL-6) and tumor necrosis factor- alpha (TNF-alpha), suppress free radical generation, enhance NO generation; and accelerate tissue repair. Thus, beneficial actions of EPA/DHA and aspirin in CHD could be attributed to the formation of LXs, resolvins, protectins, and nitrolipids and suggest that their plasma levels aid in the prediction and prognosis of CHD.
Curr Atheroscler Rep. 2007 Dec;9(6):494-500.
Monounsaturated fatty acids and atherosclerosis: opposing views from epidemiology and experimental animal models.
Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1040, USA.
ABSTRACT: A substantial body of epidemiologic data has shed light on the potential protective effects of the Mediterranean diet against atherosclerosis in humans. Many believe the reason the Mediterranean diet is atheroprotective is the elevated consumption of olive oil, an oil poor in saturated fatty acids (SFA) and highly enriched in monounsaturated fatty acids (MUFA). Based on human feeding studies, the American Heart Association and the US Food and Drug Administration have advocated for the consumption of MUFA as a more healthy replacement for SFA. However, using experimental animal models in which extent of atherosclerosis can be directly measured following dietary intervention, it has been demonstrated that MUFA-enriched diets are not atheroprotective when compared with SFA-enriched diets. Hence, the current body of experimental evidence refutes the idea that MUFAs per se are atheroprotective; therefore much additional work is needed to determine which aspects of the Mediterranean diet are indeed heart healthy.
Biochim Biophys Acta. 2005 Mar 21;1733(1):76-89.
Phosphatidylcholine-rich acceptors, but not native HDL or its apolipoproteins, mobilize cholesterol from cholesterol-rich insoluble components of human atherosclerotic plaques.
Gerontology Division, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
ABSTRACT: To examine the potential of high density lipoproteins (HDL) to ameliorate atherosclerotic plaques in vivo, we examined the ability of native HDL, lipid-free HDL apolipoproteins (apo HDL), cholesterol-free discoidal reconstituted HDL (R-HDL) comprised of apo HDL and phosphatidylcholine (PC) and PC liposomes to release cholesterol from cholesterol-rich insoluble components of plaques (ICP) isolated from atherosclerotic human aorta. Isolated ICP had a free cholesterol (FC) to phospholipid (PL) mass ratio (0.8-3.1) and a sphingomyelin (SPM) to PC mass ratio (1.2-4.2) that exceeded those of plasma membranes of cultured cells. Surprisingly, native HDL and its apolipoproteins were not able to release cholesterol from ICP. However, R-HDL and PC liposomes were effectively released cholesterol from ICP. The release of ICP cholesterol by R-HDL was dose-dependent and accompanied by the transfer of > 8 x more PC in the reverse direction (i.e., from R-HDL to ICP), resulting in a marked enrichment of ICP with PC. Compared to R-HDL, PC liposomes were significantly less effective in releasing cholesterol from ICP but were somewhat more effective in enriching ICP with PC. Native HDL was minimally effective in enriching ICP with PC, but became effective after prior in vitro enrichment of HDL with PC from multilamellar PC liposomes. The enrichment of ICP with PC resulted in the dissolution of cholesterol crystals on ICP and allowed the removal of ICP cholesterol by apo HDL and plasma. Our study revealed that the removal of cholesterol from ICP in vivo will be possible through a change in the level, composition, and physical state of ICP lipids mediated by PC-enriched HDL.
J Lipid Res. 2005 Jul;46(7):1457-65.
Structural modification of plasma HDL by phospholipids promotes efficient ABCA1-mediated cholesterol release.
Cardiovascular Genetics Laboratory, Cardiology Division, McGill University Health Center/Royal Victoria Hospital, Montréal, Québec H3A 1A1, Canada.
ABSTRACT: It has been suggested that ABCA1 interacts preferentially with lipid-poor apolipoprotein A-I (apoA-I). Here, we show that treatment of plasma with dimyristoyl phosphatidylcholine (DMPC) multilamellar vesicles generates preβ1-apoA-I-containing lipoproteins (LpA-I)-like particles similar to those of native plasma. Isolated preβ1-LpA-I-like particles inhibited the binding of 125I-apoA-I to ABCA1 more efficiently than HDL3 (IC50 = 2.20 ± 0.35 vs. 37.60 ± 4.78 μg/ml). We next investigated the ability of DMPC-treated plasma to promote phospholipid and unesterified (free) cholesterol efflux from J774 macrophages stimulated or not with cAMP. At 2 mg DMPC/ml plasma, both phospholipid and free cholesterol efflux were increased (∼50% and 40%, respectively) in cAMP-stimulated cells compared with unstimulated cells. Similarly, both phospholipid and free cholesterol efflux to either isolated native preβ1-LpA-I and preβ1-LpA-I-like particles were increased significantly in stimulated cells. Furthermore, glyburide significantly inhibited phospholipid and free cholesterol efflux to DMPC-treated plasma. Removal of apoA-I-containing lipoproteins from normolipidemic plasma drastically reduced free cholesterol efflux mediated by DMPC-treated plasma. Finally, treatment of Tangier disease plasma with DMPC affected the amount of neither preβ1-LpA-I nor free cholesterol efflux. These results indicate that DMPC enrichment of normal plasma resulted in the redistribution of apoA-I from α-HDL to preβ-HDL, allowing for more efficient ABCA1-mediated cellular lipid release. Increasing the plasma preβ1-LpA-I level by either pharmacological agents or direct infusions might prevent foam cell formation and reduce atherosclerotic vascular disease.
J Lipid Res. 2005 Jul;46(7):1457-65.
Structural modification of plasma HDL by phospholipids promotes efficient ABCA1-mediated cholesterol release.
Cardiovascular Genetics Laboratory, Cardiology Division, McGill University Health Center/Royal Victoria Hospital, Montréal, Québec H3A 1A1, Canada.
ABSTRACT: It has been suggested that ABCA1 interacts preferentially with lipid-poor apolipoprotein A-I (apoA-I). Here, we show that treatment of plasma with dimyristoyl phosphatidylcholine (DMPC) multilamellar vesicles generates prebeta(1)-apoA-I-containing lipoproteins (LpA-I)-like particles similar to those of native plasma. Isolated prebeta(1)-LpA-I-like particles inhibited the binding of (125)I-apoA-I to ABCA1 more efficiently than HDL(3) (IC(50) = 2.20 +/- 0.35 vs. 37.60 +/- 4.78 microg/ml). We next investigated the ability of DMPC-treated plasma to promote phospholipid and unesterified (free) cholesterol efflux from J774 macrophages stimulated or not with cAMP. At 2 mg DMPC/ml plasma, both phospholipid and free cholesterol efflux were increased ( approximately 50% and 40%, respectively) in cAMP-stimulated cells compared with unstimulated cells. Similarly, both phospholipid and free cholesterol efflux to either isolated native prebeta(1)-LpA-I and prebeta(1)-LpA-I-like particles were increased significantly in stimulated cells. Furthermore, glyburide significantly inhibited phospholipid
and free cholesterol efflux to DMPC-treated plasma. Removal of apoA-I-containing lipoproteins from normolipidemic plasma drastically reduced free cholesterol efflux mediated by DMPC-treated plasma. Finally, treatment of Tangier disease plasma with DMPC affected the amount of neither prebeta(1)-LpA-I nor free cholesterol efflux. These results indicate that DMPC enrichment of normal plasma resulted in the redistribution of apoA-I from alpha-HDL to prebeta-HDL, allowing for more efficient ABCA1-mediated cellular lipid release. Increasing the plasma prebeta(1)-LpA-I level by either pharmacological agents or direct infusions might prevent foam cell formation and reduce atherosclerotic vascular disease.
Am J Clin Nutr. 2005 Jul;82(1):111-7.
Choline supplemented as phosphatidylcholine decreases fasting and postmethionine-loading plasma homocysteine concentrations in healthy men.
Wageningen Centre for Food Sciences and the Division of Human Nutrition, Wageningen University, Wageningen, Netherlands Quality of Life, Zeist, Netherlands.
BACKGROUND: A high homocysteine concentration is a potential risk factor for cardiovascular disease that can be reduced through betaine supplementation. Choline is the precursor for betaine, but the effects of choline supplementation on plasma total homocysteine (tHcy) concentrations in healthy humans are unknown.
OBJECTIVE: The objective was to investigate whether supplementation with phosphatidylcholine, the form in which choline occurs in foods, reduces fasting and postmethionine-loading concentrations of plasma tHcy in healthy men with mildly elevated plasma tHcy concentrations.
DESIGN: In a crossover study, 26 men ingested approximately 2.6 g choline/d (as phosphatidylcholine) or a placebo oil mixture for 2 wk in random order. Fatty acid composition and fat content were similar for both treatments. A methionine-loading test was performed on the first and last days of each supplementation period.
RESULTS: Phosphatidylcholine supplementation for 2 wk decreased mean fasting plasma tHcy by 18% (-3.0 micromol/L; 95% CI: -3.9, -2.1 micromol/L). On the first day of supplementation, a single dose of phosphatidylcholine containing 1.5 g choline reduced the postmethionine-loading increase in tHcy by 15% (-4.8 micromol/L; 95% CI: -6.8, -2.8 micromol/L). Phosphatidylcholine supplementation for 2 wk reduced the postmethionine-loading increase in tHcy by 29% (-9.2 micromol/L; 95% CI: -11.3, -7.2 micromol/L). All changes were relative to placebo.
CONCLUSIONS: A high daily dose of choline, supplemented as phosphatidylcholine, lowers fasting as well as postmethionine-loading plasma tHcy concentrations in healthy men with mildly elevated tHcy concentrations. If high homocysteine concentrations indeed cause cardiovascular disease, choline intake may reduce cardiovascular disease risk in humans.
Circulation. 2003 Oct 7;108(14):1735-9.
Oral synthetic phospholipid (DMPC) raises high-density lipoprotein cholesterol levels, improves high-density lipoprotein function, and markedly reduces atherosclerosis in apolipoprotein E-null mice.
Division of Cardiology, Department of Medicine, David Geffen School of Medicine at the University of California Los Angeles, Room 47-123 CHS, 10833 Le Conte Ave, Los Angeles, Calif 90095-1679, USA.
BACKGROUND: Lecithin has been widely sold as a dietary supplement. 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) is a phospholipid that does not exist in nature and has been used in vitro to study lipid binding. We tested DMPC in vivo in apolipoprotein (apo) E-null mice.
METHODS AND RESULTS: DMPC or soy or egg lecithin at 1.0 mg/mL was added to the drinking water of 4-week-old apoE-null female mice. Eight weeks later, HDL cholesterol levels and apoA-I levels were markedly increased in the mice that received DMPC. HDL function was also dramatically improved in the mice receiving DMPC, and there was a significant reduction in aortic lesions (P=0.021) in the DMPC mice but not in those receiving lecithin. Adding 1.0 mg/mL of DMPC to the drinking water of 10-month-old apoE-null female mice for 5 weeks caused regression of aortic sinus lesions (P=0.003). Adding 1.0 mg/mL DMPC to the drinking water of 6-month-old apoE-null male mice for 8 weeks significantly reduced aortic sinus lesion area (P=0.0031) and en face whole aorta lesion area (P=0.001), whereas adding the same concentrations of soy or egg lecithin did not significantly alter lesion area. Jejunal apoA-I synthesis and plasma apoA-I levels were increased 2- to 3-fold in mice receiving DMPC but not soy or egg lecithin.
CONCLUSIONS: DMPC (but not lecithin) raises HDL cholesterol and apoA-I, improves HDL function, and prevents lesions or causes their regression in apoE-null mice.
Am J Physiol Regul Integr Comp Physiol. 2002 Aug;283(2):R389-99.
Heat acclimation in rats: modulation via lipid polyunsaturation.
Department of Biochemistry, The Hebrew University, Hadassah Medical School, Jerusalem 91120, Israel.
ABSTRACT: Heat acclimation of rats has been shown to enhance endurance of rat hearts to ischemic insult and acute heat stress. Common protective features have been shown to be operative during both these stress-inducing conditions. To explore the role of membrane lipid composition in the adaptive response, we analyzed two major parameters that impact membrane dynamics and order, the nonesterified cholesterol levels and the acyl chain composition of phospholipids, in rat heart and salivary glands, both major thermoregulatory organs, in short- and long-term heat-acclimated rats. Before exposure to heat, control salivary gland tissue has a higher cholesterol-to-phospholipid mole ratio (0.32 +/- 0.02) than heart (0.14 +/- 0.01), and the acyl chains of its phospholipids are 50% more saturated. The remodeling strategies of the tissues after exposure to heat differed. Heart cholesterol levels increased after short-term heat acclimation (approximately 50%), whereas salivary gland cholesterol levels decreased in acute heat stress and long-term heat acclimation (approximately 32%). Remodeling of phospholipid acyl chains, particularly an increase in docosahexaenoic acid, was a protective strategy in both tissues (57% in heart and >100% in salivary glands). Modifying membrane lipid composition by treating rats with liposomes composed of egg phosphatidylcholine (PC) before exposure to heat resulted in a 38% increase in endurance to thermal stress. The density and affinity of muscarinic receptors of submaxillary salivary glands, involved in the acclimation response, were measured in control and PC liposome-treated rats, and then both groups were subjected to short-term heat acclimation. After PC treatment the well-established compensatory up-regulation of the muscarinic receptors and concomitant decrease in their affinity was blunted. The substantial increase in the thermal endurance of heat-challenged intact rats after treatment with PC liposomes (600 vs. 200 min) suggests that membrane lipid composition plays a role in the ability of these tissues to respond to heat stress.
Proc Natl Acad Sci U S A. 2001 Nov 6;98(23):13294-9.
Compared with saturated fatty acids, dietary monounsaturated fatty acids and carbohydrates increase atherosclerosis and VLDL cholesterol levels in LDL receptor-deficient, but not apolipoprotein E-deficient, mice.
Laboratory of Biochemical Geneticsand Metabolism, Rockefeller University, New York, NY 10021, USA.
ABSTRACT: Heart-healthy dietary recommendations include decreasing the intake of saturated fatty acids (SFA). However, the relative benefit of replacing SFA with monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), or carbohydrates (CARB) is still being debated. We have used two mouse models of atherosclerosis, low density lipoprotein receptor-deficient (LDLRKO) and apolipoprotein E-deficient (apoEKO) mice to measure the effects of four isocaloric diets enriched with either SFA, MUFA, PUFA, or CARB on atherosclerotic lesion area and lipoprotein levels. In LDLRKO mice, compared with the SFA diet, the MUFA and CARB diets significantly increased atherosclerosis in both sexes, but the PUFA diet had no effect. The MUFA and CARB diets also increased very low density lipoprotein-cholesterol (VLDL-C) and LDL-cholesterol (LDL-C) in males and VLDL-C levels in females. Analysis of data from LDLRKO mice on all diets showed that atherosclerotic lesion area correlated positively with VLDL-C levels (males: r = 0.47, P < 0.005; females: r = 0.52, P < 0.001). In contrast, in apoEKO mice there were no significant dietary effects on atherosclerosis in either sex. Compared with the SFA diet, the CARB diet significantly decreased VLDL-C in males and the MUFA, PUFA, and CARB diets decreased VLDL-C and the CARB diet decreased LDL-C in females. In summary, in LDLRKO mice the replacement of dietary SFA by either MUFA or CARB causes a proportionate increase in both atherosclerotic lesion area and VLDL-C. There were no significant dietary effects on atherosclerotic lesion area in apoEKO mice. These results are surprising and suggest that, depending on the underlying genotype, dietary MUFA and CARB can actually increase atherosclerosis susceptibility, probably by raising VLDL-C levels through a non-LDL receptor, apoE-dependent pathway.
J Biol Chem. 2000 Nov 24;275(47):36596-604.
High density lipoprotein phospholipid composition is a major determinant of the bi-directional flux and net movement of cellular free cholesterol mediated by scavenger receptor BI.
Division of Gastroenterology and Nutrition, Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.
ABSTRACT: The role of high density lipoprotein (HDL) phospholipid in scavenger receptor BI (SR-BI)-mediated free cholesterol flux was examined by manipulating HDL(3) phosphatidylcholine and sphingomyelin content. Both phosphatidylcholine and sphingomyelin enrichment of HDL enhanced the net efflux of cholesterol from SR-BI-expressing COS-7 cells but by two different mechanisms.
Phosphatidylcholine enrichment of HDL increased efflux, whereas sphingomyelin enrichment decreased influx of HDL cholesterol. Although similar trends were observed in control (vector-transfected) COS-7 cells, SR-BI overexpression amplified the effects of phosphatidylcholine and sphingomyelin enrichment of HDL 25- and 2.8-fold, respectively. By using both phosphatidylcholine-enriched and phospholipase A(2)-treated HDL to obtain HDL with a graded phosphatidylcholine content, we showed that SR-BI-mediated cholesterol efflux was highly correlated (r(2) = 0.985) with HDL phosphatidylcholine content. The effects of varying HDL phospholipid composition on SR-BI-mediated free cholesterol flux were not correlated with changes in either the K(d) or B(max) values for high affinity binding to SR-BI. We conclude that SR-BI-mediated free cholesterol flux is highly sensitive to HDL phospholipid composition. Thus, factors that regulate cellular SR-BI expression and the local modification of HDL phospholipid composition will have a large impact on reverse cholesterol transport.
Zhonghua Nei Ke Za Zhi. 1996 May;35(5):313-6.
[The effect of phospholipid liposomes on atherosclerosis and serum lipid in rabbits].
Department of Cardiology, General Hospital of Beijing Command.
ABSTRACT: In order to study the effect of oral phospholipid liposomes on regression of atherosclerosis process, serum total cholesterol triglyceride, lipoprotein cholesterol and atherosclerotic lesion on the aorta wall in different groups of 20 New Zealand rabbits were observed. Results showed that phospholipid liposomes could obviously increase high density lipoprorein cholesterol concentration and decrease serum total cholesterol triglyceride and very low density lipoprorein cholesterol concentration. Phospholipid liposomes could also reduce the size of atherosclerotic lesion on the aortic wall. In comparision with the results observed in phospholipid group, there was significant difference (P < 0.05, P < 0.01 or P < 0.001). It suggested that oral phospholipid liposomes could effectively regress atherosclerotic lesion on the arterial wall and regulate serum lipid to reduce cholesterol deposit on the arterial wall in experimental rabbits. It might provide some experimental basis for human being to prevent and treat atherosclerosis.
Cardiovasc Drugs Ther. 1995 Dec;9(6):779-84.
“Essential” phospholipids versus nicotinic acid in the treatment of patients with type IIb hyperlipoproteinemia and ischemic heart disease.
Experimental Medicine, St. Petersburg, Russia. In patients with moderate, dietary noncorrigible hyperlipoproteinemia type IIb and ischemic heart disease, treatment with nicotinic acid is limited by the side effects of the drug. In 100 patients, 6-month treatment with nicotinic acid (n = 50) or “essential” phospholipids (EPL); Lipostabil, manufacturer: Rhône-Poulenc Rorer) (n = 50) indicated comparable efficacy for both substances: Significant (p < .001) reductions of serum total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglyceride values were similar in both groups, while nicotinic acid increased high-density lipoprotein (HDL) cholesterol significantly (p < .01) better than Lipostabil. A detailed analysis of ultracentrifugal lipoprotein profiles, hydroperoxide concentrations in LDL, and cholesterol-accepting properties of HDL in a small number of Lipostabil- and nicotinic acid-treated patients revealed favorable shifts in the lipoprotein profile, significant (p < .05) reductions of LDL hydroperoxides, and favorable increases of the most antiatherogenic HDL2b subfraction only in the Lipostabil-treated group. Clinically, both medications reduced the intensity and number of 131 angina pectoris attacks per week (p < .05), but only Lipostabil-treated patients significantly (p < .05) increased their working capacity in the veloergometric test. Since in the nicotinic acid-treated group dropouts (nine patients, eight related to the drug) and side effects  exceeded those in the Lipostabil-treated group (two dropouts not related to the drug, no side effects), it is suggested that Lipostabil is a preferable alternative in the treatment of patients with moderate, dietary noncorrigible hyperlipoproteinemia IIb and ischemic heart disease.
Am J Physiol. 1995 Feb;268(2 Pt 2)
Cholesterol distribution in rat heart myocytes.
Department of Biochemistry, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
ABSTRACT: Cholesterol oxidase was used to investigate the distribution of free cholesterol between plasma membrane and intracellular pools in cultured neonatal rat heart myocytes. Only 20% of the total unesterified cholesterol was converted to delta 4-cholestenone by cholesterol oxidase in intact cells. With increasing age in culture and concurrent hypertrophy, there was an increase in unesterified cellular cholesterol and plasma membrane cholesterol; their relative distribution remained unchanged. Electron micrographs of negatively stained samples of day 4 cytosol revealed the presence of vesicles 50-200 nm in diameter. Cholesterol monohydrate crystals were found in the cytosol of hypertrophic day 14 cells. Treatment of day 14 cells with small unilamellar vesicles of egg phosphatidylcholine reduced plasma membrane and intracellular cholesterol levels , resulting in the disappearance of the cholesterol monohydrate crystals and the formation of vesicles smaller than those observed in day 4 cultures
Ann Nutr Metab. 1994;38(3):117-22.
Polyunsaturated and monounsaturated fatty acids in the diet to prevent coronary heart disease via cholesterol reduction.
Department of Community and Family Medicine, Duke University Medical Center, Durham, N.C.
ABSTRACT: For over 30 years the American Heart Association recommended to limit the fat intake to 30 energy % (E%) of total calories with 10 E% derived from polyunsaturated fatty acids (PUFA), 10 E% from monounsaturated fatty acids (MUFA) and 10 E% from saturated fatty acids (SFA). In 1988 and subsequent years, the National Cholesterol Education Program has changed this advise in favor of an increase of 15 E% MUFA and a reduction to 5 E% PUFA. This dramatic change was based largely on short-term dietary experiments, with formula diets with small numbers of subjects, and anecdotal epidemiological evidence from the population of Crete. The assertion that oleic acid may lower cholesterol and LDL remains unproven. However, isocaloric substitution of linoleic acid for oleic acid lowers cholesterol and LDL. Oleicacid has little or no effect on lipids and lipoproteins except as it replaces SFA . Large dietary feeding experiments in the 1950s and 1960s with persons with hypercholesterolemia and with patients after myocardial infarction were conducted with PUFA-enriched diets and proved effective in primary and secondary prevention of coronary heart disease. No such studies exist with MUFA-enriched diets. Therefore, the original recommendations remain the standard of dietary advise to healthy persons and patients after myocardial infarction.
Proc Natl Acad Sci USA. 1988 Jan;85(1):242-6.
Low density lipoprotein receptor-independent hepatic uptake of a synthetic, cholesterol-scavenging lipoprotein: implications for the treatment of receptor-deficient atherosclerosis.
Department of Medicine, Columbia University, College of Physicians & Surgeons, New York, NY 10032.
ABSTRACT: The metabolism of infused 111In-labeled phospholipid liposomes was examined in Watanabe heritable hyperlipidemic (WHHL) rabbits, which lack low density lipoprotein (LDL) receptors, and in normal control rabbits. The half-times (t1/2) for clearance of 111In and excess phospholipid from plasma were 20.8 +/- 0.9 hr and 20.3 +/- 4.6 hr in WHHL and 20.0 +/- 0.8 hr and 19.6 +/- 2.2 hr in the normal rabbits (means +/- SEM; n = 4). By 6 hr postinfusion, the plasma concentration of unesterified cholesterol increased by 2.2 +/- 0.23 mmol/liter in WHHL and 2.1 +/- 0.04 mmol/liter in normal rabbits, presumably reflecting mobilization of tissue stores. Disappearance of excess plasma cholesterol was greater than 90% complete in both groups of rabbits by 70 hr postinfusion. By quantitative gamma camera imaging, hepatic trapping of 111In-labeled liposomes over time was indistinguishable between the two groups. At autopsy, the liver was the major organ of clearance, acquiring 22.0% +/- 1.7% (WHHL) and 16.8% +/- 1.0% (normal of total 111In. Aortic uptake of 111In was less than 0.02%. Thus, mobilization of cholesterol and hepatic uptake of phospholipid liposomes do not require LDL receptors. Because phospholipid infusions produce rapid substantial regression of atherosclerosis in genetically normal animals, our results suggest that phospholipid liposomes or triglyceride phospholipid emulsions (e.g., Intralipid) might reduce atherosclerosis in WHHL rabbits and in humans with familial hypercholesterolemia.
J Lipid Res. 1988 Nov;29(11):1405-15.
Behavior of human apolipoprotein A-I: phospholipid and apoHDL:phospholipid complexes in vitro and after injection into rabbits.
MRC Lipoprotein Team, Hammersmith Hospital, London, U.K.
ABSTRACT: Apolipoprotein A-I was purified from human high density lipoprotein and complexed with polyunsaturated phosphatidylcholine (PC) in deoxycholate (Lipostabil); the bile salt was removed subsequently by dialysis. The behavior of the resultant apoA-I/PC complexes was compared with that of Lipostabil in vitro and after injection into rabbits. In vivo apoA-I/PC complexes had the density of HDL throughout but had both alpha and pre beta electrophoretic mobility, the latter probably reflecting dissociation of apoA-I from PC. Lipostabil initially behaved like LDL but gradually acquired the density of HDL after incubation with plasma and in vivo. Both preparations increased plasma total phospholipids in normolipidemic rabbits to a similar extent, but, increments in HDL phospholipid were greater after apoA-I/PC complexes were injected. ApoHDL/PC complexes, prepared in a similar manner, appeared to promote efflux of cholesterol from perfused rabbit aortas in the presence of lecithin:cholesterol acyltransferase (LCAT) activity, consistent with a stimulatory effect on cholesterol mobilization. Injection of apoHDL/PC complexes into hyperlipidemic rabbits decreased plasma cholesterol but increased HDL cholesterol, whereas Lipostabil decreased both. These findings suggest that human apoA-I/PC complexes resemble HDL in their behavior more closely than does Lipostabil, and show that both types of liposome undergo modification upon interaction with plasma. It remains to be shown whether they possess any therapeutic potential.
JPEN J Parenter Enteral Nutr. 1985 Nov-Dec;9(6):716-9.
The effects of oral soybean phospholipid on serum total cholesterol, plasma triglyceride, and serum high-density lipoprotein cholesterol concentrations in hyperlipidemia.
ABSTRACT: In a randomized, double-blind, cross-over trial soybean phospholipid and placebo, 18 g daily for 6 wk, were given orally to 20 patients on long-term treatment with standard lipid lowering diets. The effect of this treatment on serum total cholesterol and high-density lipoprotein cholesterol and plasma triglyceride was studied. After 6 wk mean (+/- SE) cholesterol concentration was decreased by 0.54 (+/- 0.19) mmol/liter in phospholipid-treated as compared to placebo-treated patients (p less than 0.02). The decrease in serum cholesterol was significant (p less than 0.02) only in patients assigned to receive phospholipid before placebo. A highly significant increase (p less than 0.001) followed the withdrawal of phospholipid. No effect on triglyceride and high-density lipoprotein cholesterol concentrations was demonstrated.
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