Reduced Plasma Cholesterol Research Articles

Statin action favors normalization of the plasma lipidome in the atherogenic mixed dyslipidemia of MetS: potential relevance to statin-associated dysglycemia

The impact of statin treatment on the abnormal plasma lipidome of mixed dyslipidemic patients with metabolic syndrome (MetS), a group at increased risk of developing diabetes, was evaluated. Insulin-resistant hypertriglyceridemic hypertensive obese males (n = 12) displaying MetS were treated with pitavastatin (4 mg/day) for 180 days; healthy normolipidemic age-matched nonobese males (n = 12) acted as controls. Statin treatment substantially normalized triglyceride (−41%), remnant cholesterol (−55%), and LDL-cholesterol (−39%), with minor effect on HDL-cholesterol (+4%). Lipidomic analysis, normalized to nonHDL-cholesterol in order to probe statin-induced differences in molecular composition independently of reduction in plasma cholesterol, revealed increment in 132 of 138 lipid species that were subnormal at baseline and significantly shifted toward the control group on statin treatment. Increment in alkyl- and alkenylphospholipids (plasmalogens) was prominent, and consistent with significant statin-induced increase in plasma polyunsaturated fatty acid levels. Comparison of the statin-mediated lipidomic changes in MetS with the abnormal plasma lipidomic profile characteristic of prediabetes and T2D in the Australian Diabetes, Obesity, and Lifestyle Study and San Antonio Family Heart Study cohorts by hypergeometric analysis revealed a significant shift toward the lipid profile of controls, indicative of a marked trend toward a normolipidemic phenotype. Pitavastatin attenuated the abnormal plasma lipidome of MetS patients typical of prediabetes and T2D.

Diet, nutrition and osteoarthritis

Osteoarthritis (OA) is the fastest growing cause of disability worldwide[1]. In the absence of effective therapies, patients may wish to take some control of their own condition by making dietary changes that have the potential to ameliorate symptoms or reduce disease progression. A number of dietary factors have been associated with OA symptoms or progression. Most notably, in those overweight, weight reduction of ≥10% has the potential to lead to important changes in pain and function[2]. Losing weight also reduces pain-associated inflammation[3]. Weight loss combined with physical activity has an even greater capacity to improve pain and function[4]. It has been suggested that OA is a metabolic disease in which lipids essentially contribute to the pathophysiology of cartilage degradation[5]. Dietary long-chain ω-3 PUFA may affect articular cartilage composition and appear to have beneficial effects in OA[5]. In a US cohort of individuals with, or at high risk of, knee OA, there was a significant inverse relationship between total n-3 PUFAs and patella-femoral cartilage loss[6]. A positive association has been shown between elevated serum cholesterol and OA; hypercholesterolemia (OR 1.61; 95% CI 1.06-2.47) and high serum cholesterol (3rd vs. 1st tertile: OR 1.73; 95% CI 1.02-2.92) were independently associated with generalized OA in the Ulm study [7]. Hence there may be a potential benefit in adopting dietary cholesterol-lowering strategies (such as consumption of sterol/stanol spreads/drinks). Vitamin D affects the state of multiple articular structures. The evidence for association between the vitamin D biomarker, serum 25(OH)D, and OA was assessed in a systematic review. For knee radiographic OA progression and cartilage loss, there was strong evidence for an association with low 25(OH)D[8]. Vitamin K is important in cartilage metabolism as an inhibitor of extracellular matrix calcification and a promoter of cell survival/proliferation. In the US MOST study, vitamin K deficiency was associated with incident radiographic knee OA and MRI-based cartilage lesions (RR 2.39; 95% CI, 1.05-5.40) compared with no deficiency[9]. Hence, dietary recommendations are the following: ▪ lose weight, if overweight, preferably combined with exercise; ▪ reduce plasma cholesterol by dietary means; ▪ at least for a trial period, increase intake of long-chain n-3 fatty acids preferably by eating oily fish twice a week; ▪ aim for a safe level of sun exposure, eat rich vitamin-D dietary sources or take vitamin D supplements, ≤ 25 μg/d; ▪ increase vitamin K intake by eating green leafy vegetables.

Atorvastatin protects endothelial colony‑forming cells against H2O2‑induced oxidative damage by regulating the expression of annexin A2.

Endothelial dysfunction and injury are central events in the pathogenesis of ischemic vascular disorders. Endothelial progenitor cells (EPCs) are mobilized from the bone marrow into the peripheral circulation, where they locate to sites of injured endothelium and are involved in endothelial repair and vascular regeneration. During these processes, EPCs are exposed to oxidative stress, a crucial pathological condition, which occurs during vascular injury and limits the efficacy of EPCs in the repair of injured endothelium. Statins are effective inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase, and are commonly used to manage and prevent ischemic vascular disease by reducing plasma cholesterol levels. In addition to lowering cholesterol, statins have also been reported to exert pleiotropic actions, including anti-inflammatory and anti-oxidative activities. The present study aimed to investigate the ability of atorvastatin to protect endothelial colony-forming cells (ECFCs), a homogeneous subtype of EPCs, from hydrogen peroxide (H2O2)-induced oxidative damage, and to determine the mechanism underlying this protective action. MTT assay, acridine orange/ethidium bromide staining, reactive oxygen species assay, western blot analysis and tube formation assay were employed. The results demonstrated that H2O2 induced cell death and decreased the tube-forming ability of the ECFCs, in a concentration-dependent manner; however, these effects were partially attenuated following administration of atorvastatin. The reversion of the quantitative and qualitative impairment of the H2O2-treated ECFCs appeared to be mediated by the regulation of annexin A2, as the expression levels of annexin A2 were decreased following treatment with H2O2 and increased following treatment with atorvastatin. These results indicated that annexin A2 may be involved in the H2O2-induced damage of ECFCs, and in the protective activities of atorvastatin in response to oxidative stress.

Altered metabolism of LDL in the arterial wall precedes atherosclerosis regression.

Plasma cholesterol lowering is beneficial in patients with atherosclerosis. However, it is unknown how it affects entry and degradation of low-density lipoprotein (LDL) particles in the lesioned arterial wall. We studied the effect of lipid-lowering therapy on LDL permeability and degradation of LDL particles in atherosclerotic aortas of mice by measuring the accumulation of iodinated LDL particles in the arterial wall. Cholesterol-fed, LDL receptor-deficient mice were treated with either an anti-Apob antisense oligonucleotide or a mismatch control antisense oligonucleotide once a week for 1 or 4 weeks before injection with preparations of iodinated LDL particles. The anti-Apob antisense oligonucleotide reduced plasma cholesterol by ≈90%. The aortic LDL permeability and degradation rates of newly entered LDL particles were reduced by ≈50% and ≈85% already after 1 week of treatment despite an unchanged pool size of aortic iodinated LDL particles. In contrast, the size, foam cell content, and aortic pool size of iodinated LDL particles of aortic atherosclerotic plaques were not reduced until after 4 weeks of treatment with the anti-Apob antisense oligonucleotide. Improved endothelial barrier function toward the entry of plasma LDL particles and diminished aortic degradation of the newly entered LDL particles precede plaque regression.

Lipid-lowering Activity of Natural and Semi-Synthetic Sterols and Stanols.

Consumption of plant sterols/ stanols has long been demonstrated to reduce plasma cholesterol levels. The objective of this review is to demonstrate the lipid-lowering activity and anti-atherogenic effects of natural and semi-synthetic plant sterols/ stanols based on evidence from cell-culture studies, animal studies and clinical trials. Additionally, this review highlights certain molecular mechanisms by which plant sterols/ stanols lower plasma cholesterol levels with a special emphasis on factors that affect the cholesterol-lowering activity of plant sterols/stanols. The crystalline nature and the poor oil solubility of these natural products could be important factors that limit their cholesterol-lowering efficiency. Several attempts have been made to improve the cholesterol-lowering activity by enhancing the bioavailability of crystalline sterols and stanols. Approaches involved reduction of the crystal size and/or esterification with fatty acids from vegetable or fish oils. However, the most promising approach in this context is the chemical modification of plant sterols /stanols into water soluble disodium ascorbyl phytostanyl phosphates analogue by esterification with ascorbic acid. This novel semi-synthetic stanol derivative has improved efficacy over natural plant sterols/ stanols and can provide additional benefits by combining the cholesterol-lowering properties of plant stanols with the antioxidant potential of ascorbic acid. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

Effects of proanthocyanidin enriched extract from Ligaria cuneifolia on plasma cholesterol and hemorheological parameters. In vivo and In vitro studies.

It was demonstrated that Ligaria cuneifolia (Lc) crude extract increased blood viscosity and decreased plasma cholesterol in rats. In the present study, we analyzed the Lc proanthocyanidin enriched fraction (PLc) to determine if it is capable of altering the hemorheological parameters while diminishing the plasma cholesterol. In vivo studies in adult male Wistar rats, randomized in three groups (n = 6 each one) were performed: 1. saline intraperitoneal (i.p.); 2. PLc 0.6 mg/100 g body weight (b.w.) i.p. and 3. PLc 3 mg/100 g b.w. i.p., every 24 hours during 3 days. with blood obtained by cardiac puncture, separated in aliquots and incubated with: 1. Saline solution (Control); 2. PLc 0.1 mg/mL, and 3. PLc 1.0 mg/mL, equivalent to doses in vivo experiments. The results demonstrated that in vivo PLc 0.6 and PLc 3 reduced plasma cholesterol (Cho) and LDL-Cho. Neither blood nor plasma viscosity was altered. Decrease of plasma cholesterol could be due to an increase of cholesterol and bile salts excretion leading to an increase of bile flow. In vitro experiments showed a direct interaction of PLc, at high concentration, with the erythrocyte membrane, inducing a switch from discocyte to stomatocyte. Only, PLc without hepatic metabolism produces hemorheological changes. Thus, PLc in vivo might be a pharmacological agent capable of decreasing plasma cholesterol.

Inactivation of ANGPTL3 reduces hepatic VLDL-triglyceride secretion

Humans and mice lacking angiopoietin-like protein 3 (ANGPTL3) have pan-hypolipidemia. ANGPTL3 inhibits two intravascular lipases, LPL and endothelial lipase, and the low plasma TG and HDL-cholesterol levels in ANGPTL3 deficiency reflect increased activity of these enzymes. The mechanism responsible for the low LDL-cholesterol levels associated with ANGPTL3 deficiency is not known. Here we used an anti-ANGPTL3 monoclonal antibody (REGN1500) to inactivate ANGPTL3 in mice with genetic deficiencies in key proteins involved in clearance of ApoB-containing lipoproteins. REGN1500 treatment consistently reduced plasma cholesterol levels in mice in which Apoe, Ldlr, Lrp1, and Sdc1 were inactivated singly or in combination, but did not alter clearance of rabbit (125)I-βVLDL or mouse (125)I-LDL. Despite a 61% reduction in VLDL-TG production, VLDL-ApoB-100 production was unchanged in REGN1500-treated animals. Hepatic TG content, fatty acid synthesis, and fatty acid oxidation were similar in REGN1500 and control antibody-treated animals. Taken together, our findings indicate that inactivation of ANGPTL3 does not affect the number of ApoB-containing lipoproteins secreted by the liver but alters the particles that are made such that they are cleared more rapidly from the circulation via a noncanonical pathway(s). The increased clearance of lipolytic remnants results in decreased production of LDL in ANGPTL3-deficient animals.

Effects of High Fat Feeding and Diabetes on Regression of Atherosclerosis Induced by Low-Density Lipoprotein Receptor Gene Therapy in LDL Receptor-Deficient Mice.

We tested whether a high fat diet (HFD) containing the inflammatory dietary fatty acid palmitate or insulin deficient diabetes altered the remodeling of atherosclerotic plaques in LDL receptor knockout (Ldlr-/-) mice. Cholesterol reduction was achieved by using a helper-dependent adenovirus (HDAd) carrying the gene for the low-density lipoprotein receptor (Ldlr; HDAd-LDLR). After injection of the HDAd-LDLR, mice consuming either HFD, which led to insulin resistance but not hyperglycemia, or low fat diet (LFD), showed regression compared to baseline. However there was no difference between the two groups in terms of atherosclerotic lesion size, or CD68+ cell and lipid content. Because of the lack of effects of these two diets, we then tested whether viral-mediated cholesterol reduction would lead to defective regression in mice with greater hyperglycemia. In both normoglycemic and streptozotocin (STZ)-treated hyperglycemic mice, HDAd-LDLR significantly reduced plasma cholesterol levels, decreased atherosclerotic lesion size, reduced macrophage area and lipid content, and increased collagen content of plaque in the aortic sinus. However, reductions in anti-inflammatory and ER stress-related genes were less pronounced in STZ-diabetic mice compared to non-diabetic mice. In conclusion, HDAd-mediated Ldlr gene therapy is an effective and simple method to induce atherosclerosis regression in Ldlr-/- mice in different metabolic states.

Associations of ApoAI and ApoB-containing lipoproteins with AngII-induced abdominal aortic aneurysms in mice.

Dyslipidemia is implicated in abdominal aortic aneurysms (AAAs) in humans and angiotensin (Ang) II-infused mice. This study determined effects of major lipoprotein classes on AngII-induced AAAs using multiple mouse strains with dietary and pharmacological manipulations. Western diet had minor effects on plasma cholesterol concentrations and the low incidence of AngII-induced AAAs in C57BL/6J mice. Low incidence of AAAs in this strain was not attributed to protection from high-density lipoprotein, because apolipoprotein (apo) AI deficiency did not increase AngII-induced AAAs. ApoAI deletion also failed to alter AAA occurrence in hypercholesterolemic mice. Low-density lipoprotein receptor-/- mice fed normal diet had low incidence of AngII-induced AAAs. Western diet feeding of this strain provoked pronounced hypercholesterolemia because of increased apoB-containing lipoproteins with attendant increases of atherosclerosis in both sexes, but AAAs only in male mice. ApoE-deficient mice fed normal diet were modestly hypercholesterolemic, whereas this strain fed Western diet was severely hypercholesterolemic because of increased apoB-containing lipoprotein concentrations. The latter augmented atherosclerosis, but did not change the high incidence of AAAs in this strain. To determine whether reductions in apoB-containing lipoproteins influenced AngII-induced AAAs, ezetimibe was administered at a dose that partially reduced plasma cholesterol concentrations to ApoE-deficient mice fed Western diet. This decreased atherosclerosis, but not AAAs. This ezetimibe dose in ApoE-deficient mice fed normal diet significantly decreased plasma apoB-containing lipoprotein concentrations and reduced AngII-induced AAAs. ApoB-containing lipoproteins contribute to augmentation of AngII-induced AAA in male mice. However, unlike atherosclerosis, AAA occurrence was not correlated with increases in plasma apoB-containing lipoprotein concentrations.

Abstract 334: The LXRβ Selective Agonist, VTP-38443, Significantly Decreases Plaque Cholesterol Ester Content and Inflammation in a Murine Model of Accelerated Atherosclerosis

The ligand-activated transcription factors LXRα and LXRβ are important regulators of cholesterol metabolism and inflammation. Activation of LXR was previously shown to inhibit atherosclerosis in animal models through activation of reverse cholesterol transport (RCT) and suppression of vascular inflammation. VTP-38443 is a potent selective and orally bioavailable modulator of LXRβ that is being pursued for the prevention of subsequent vascular events following an acute coronary syndrome (ACS) episode. VTP-38443 is a potent binder (Ki=12 nM) and activator (EC50=17 nM) of LXRβ. It is ~20x selective for LXRβ versus LXRβ in both binding and activation. In primary human cells, it induces the expression of the cholesterol efflux pumps ABCA1 and ABCG1, markers of RCT, and promotes cholesterol efflux from human fibroblasts at low concentrations (EC50 = 14 nM). Orally dosed VTP-38443 demonstrates robust induction of ABCA1 and ABCG1 in mice (ED50 < 0.3 mg/kg) and primates (ED50 < 0.1 mg/kg). Based on this robust activity, VTP-38443 was tested in the apoE -/- carotid artery ligated mouse model, an accelerated atherosclerosis model. ApoE-/- mice (9 week) were fed a Western diet for 2 weeks at which point the left common carotid artery was ligated. Mice remained on the Western diet for 2 weeks post-surgery and were dosed BID with VTP-38443 (0.05, 0.2 and 1 mg/kg/dose) or a non-selective LXR agonist, TO90137 (20 mg/kg/day) during this time. Plasma cholesterol and TGs were measured as were cholesterol esters and FDG-6-phosphate, a biomarker of plaque inflammation, in the carotid plaques. VTP-38443 gave a dose-dependent reduction in plasma cholesterol (35% at 1 mg/kg) and a modest dose-dependent increase in plasma TGs ranging from 5% to 45% of the TG increase seen with TO90137. Plaque analysis showed a highly significant decrease in carotid cholesterol ester content at all doses, achieving >90% reduction at the highest dose. In addition, there was a significant reduction (~40-50%) in FDG-6 phosphate at all doses of VTP-38443, indicating a decrease in vascular inflammation. These data indicate that LXRβ activation may decrease plaque cholesterol content and reduce plaque inflammation in ACS.

Abstract 203: Redox Regulation of MKP-1 and the Functional Reprogramming of Monocyte-Derived Macrophages by Metabolic Stress

Objective: To determine the mechanisms through which MKP-1 deficiency in monocytes and macrophages promotes atherogenesis. Methods and Results: Transplantation of MKP-1-deficient (MKP KO ) bone marrow into LDL-R -/- (MKP-1 LeuKO ) mice accelerated high fat diet (HFD)-induced atherosclerotic lesion formation. After 12 weeks of HFD feeding, MKP-1 LeuKO mice showed increases in lesion size in both the aortic root and the aorta, despite reduced plasma cholesterol levels. Macrophage content was increased in lesions of MKP-1 LeuKO mice compared to mice that received wt bone marrow. After only 6 weeks on a HFD, the in vivo chemotactic activity of monocytes was already significantly increased in MKP-1 LeuKO mice. Macrophages isolated from MKP KO mice showed impaired autophagy, increased sensitivity to 7-ketocholesterol-induced apoptosis, and IL-4-induced M2 polarization of these macrophages was blocked. Importantly, macrophages in atherosclerotic lesion of MKP-1 LeuKO mice showed increased macrophage apoptosis and decreased autophagy. Metabolic stress in vitro mimicked the functional phenotype of MKP-1 deficiency, and overexpression of MKP-1 protected macrophages from metabolic stress-induced dysfunction and reprogramming. Conclusions: Loss of MKP-1 activity promotes monocyte dysfucntion and the functional reprogramming of monocyte-derived macrophages. MKP-1 deficiency accelerates atherosclerotic lesion formation by hyper-sensitizing monocytes to chemokine-induced recruitment, predisposing macrophages to M1 polarization, impaired autophagy and oxysterol-induced cell death. Reduced MKP-1 levels and activity in blood monocytes may therefore be a sensitive biomarker of increased risk of atherosclerosis.

Abstract 103: HDL Improves Cholesterol and Glucose Homeostasis and Reduces Atherosclerosis in TRAIL-/-ApoE-/- mice

Background and Aims: Atherosclerosis is characterized by the infiltration and accumulation of monocytes in the arterial wall, combined with elevated plasma low density lipoprotein (LDL) and triglycerides, and low levels of high density lipoprotein (HDL). Apolipoprotein A-I (apoA-I), the main HDL apolipoprotein, is not only athero-protective but can also increase insulin secretion from pancreatic β-cells. Our laboratory recently demonstrated that in response to a ‘western’ diet TNF-related apoptosis-inducing ligand (TRAIL)-deficiency accelerated plaque development in ApoE-/- mice, and promoted features of diabetes typical to those observed in humans. We sought to determine whether reconstituted HDL (rHDL) could improve TRAIL-dependent disease. Methods and Results: TRAIL-/-ApoE-/- and ApoE-/- mice on a ‘western’ diet for 12 w received 3 weekly infusions of either PBS (vehicle) or rHDL (20 mg/kg apoA-I, 1-palmitoyl-2-linoleoyl phosphatidylcholine) in the final 2 weeks of feeding prior to euthanasia. While no change in weight gain was observed, administration of rHDL significantly reduced plasma cholesterol, triglyceride and glucose levels, and improved glucose clearance and insulin sensitivity in TRAIL-/-ApoE-/- mice. Notably, rHDL treatment significantly attenuated atherosclerotic plaque size in brachiocephalic arteries of TRAIL-/-ApoE-/-, but not in ApoE-/- mice. rHDL-treated TRAIL-deficient mice also displayed elevated aortic mRNA expression of the ATP-binding cassette (ABC) transporters ABCA1 and ABCG1. This was associated with significantly increased expression of the pan macrophage marker F4/80 and the M2 marker CD206, suggesting that the rHDL stimulated polarization towards an M2 phenotype. Immunohistological analysis of the rHDL-treated TRAIL-/-ApoE-/- pancreata revealed increased insulin expression and reduced macrophage infiltration relative to ApoE-/- pancreata. Conclusions: This is the first demonstration of rHDL improving atherosclerosis and rescuing features of diabetes which are dependent on TRAIL. Understanding how rHDL may be beneficial in TRAIL-dependent disease could identify new strategies in the treatment of atherosclerosis and associated diabetic complications.

Emerging antiplatelet and lipid lowering therapies

Antiplatelet therapy is used widely with proven benefit for the primary prevention of cardiovascular disease as well as for the prevention of further ischemic cardiovascular events in patients with proven coronary artery disease (CAD) and in those with a history of acute coronary syndrome (ACS). The limitations of conventional antiplatelet therapy with aspirin, clopidogrel, or prasugrel, as well as the fact that rates of recurrent ischemic events still remain high with use of these agents, underscore the need to investigate alternative molecules that may be effective in further reducing the occurrence of events without increasing the risk of bleeding. The armamentarium of antiplatelet therapy has been further enriched by ticagrelor, cangrelor, vorapaxar, prasugrel and atopaxar. Ticagrelor was approved in 2011 by the European Medicines Agency swiftly followed by the US Food and Drug Administration. Reversible antiplatelet agents acting as P2Y12 antagonists similar to ticagrelor are cangrelor, and elinogrel. A new class of oral protease-activated receptor-1 (PAR-1) inhibitors, vorapaxar and atopaxar has also been proposed as effective antiplatelets but their clinical benefit is still under debate. The P2Y12 antagonists prasugrel and ticagrelor prevent adverse cardiac outcomes albeit their absolute benefit is very small. The beneficial effect of prasugrel and ticagrelor comes at a cost of an increased risk of bleeding. Furthermore, new adverse effects have also become evident with the new P2Y12 antagonists and these include dyspnea (for all of the reversible P2Y12 antagonists: ticagrelor, cangrelor, and elinogrel) and ventricular pauses for ticagrelor. In addition, the newer P2Y12 antagonists have a peculiar pharmacodynamic profile with a fast onset and offset. Two of these agents, cangrelor and elinogrel, are available as intravenous formulations, which may provide additional benefits in patients who undergo coronary artery bypass graft (CABG) surgery. Trials with the PAR-1 inhibitors have also shown trends toward reductions in cardiac events, but not without the possibility of increased bleeding. Physicians must carefully assess patient-specific factors such as risk of thrombosis, concomitant disease states, age, drug adherence, and aspirin dose, and plan for those patients who will be undergoing CABG when selecting antiplatelet therapy in order to optimally balance bleeding and thrombosis risk. In addition to adequate anti-platelet therapy the treatment of blood lipids is important for the primary and secondary prevention of cardiovascular disease. Elevated low-density lipoprotein cholesterol is an important risk factor for cardiovascular and cerebrovascular events. HMG-CoA reductase inhibitors, or statins, are very effective in lowering cholesterol levels, and in reducing mortality and cardiovascular events in patients with and without cardiovascular disease. The evidence cumulated with the studies conducted with statin has led to the recent recommendations that all patients with known vascular disease, or who are at high risk for vascular disease, should be considered candidates for statin therapy. Nonstatin therapies (either as monotherapy or in addition to statins) to reduce LDL cholesterol by mechanisms that do not involve inhibition of HMG-CoA reductase are likely to be useful for patients in need of LDL reduction; particularly those who either cannot take statins or respond only partially or not at all to statins alone. These therapies include cholesterol absorption inhibitors, Acyl-CoA cholesterol acyl transferase inhibitors, farnesoid X receptor antagonists, sterolregulating binding protein cleavage activating protein, and microsomal triglyceride transfer protein. Recent studies with the PCSK9 have shown that these drugs significantly reduce total and LDL cholesterol in patients with familial hypercholesterolaemia and that are effective in further reducing plasma cholesterol levels in patients receiving statins. Therefore, therapeutic options are becoming available for patients who cannot tolerate full dose statin therapy or for those few patients who are intolerant to statin therapy.

Abstract 358: Targeting of Heparin Binding EGF-like Growth Factor (HB-EGF) Efficiently Inhibits Atherosclerosis

Objective: Heparin-binding EGF-like growth factor (HB-EGF) is a receptor ligand that regulates inflammatory gene expression in the human aortic endothelial cells. In this study, we examined the effects of targeting HB-EGF using an antisense oligonucleotide (ASO) in the development of atherosclerosis. Methods and Results: Control and HB-EGF ASOs were injected intraperitoneally (i.p.; weekly; Dose: 50 mg/kg/wk) for 12 weeks into LDLR deficient mice fed a fat-enriched diet (21% fat; 0.2% cholesterol). Compared with the control ASO injected group (N=13), the HB-EGF ASO injected group (N=15) had efficiently reduced atherosclerosis in the arch of aorta (p<0.0001). The HB-EGF ASO also significantly reduced plasma cholesterol concentration (p = 0.0397). We observed that the VLDL was consistently reduced in all HB-EGF ASO injected mice tested. In liver tissue, the HB-EGF ASO induced significant downregulation of gene expressions of the sterol synthetic pathway as determined by a microarray and DAVID functional analysis (adjusted p = 5.5 x 10-9)). The HB-EGF ASO also induced lipid droplet accumulation in liver tissues as determined by histological analysis with liver tissue sections. Conclusions: This study indicates that HB-EGF is a key mediator for atherosclerosis and the targeting of HB-EGF is an efficient approach to inhibit lesion formation in the aorta. Downregulation of the sterol synthesis pathway and reduction of VLDL particles in the blood may contribute to the protective effects of HB-EGF ASO.

Gum arabic down-regulate PPAR-γ and SCD mRNA expression in mice

Abstract Introduction Gum arabic is a complex polysaccharide used in the food industry as a thickener and stabilizer. It reduced plasma cholesterol level in animals and humans, and it has prebiotic, anticarcinogenic and anti-oxidant effect with a protective role against hepatic and cardiac toxicities. Aim To study the impact of gum arabic on body weight, adipose tissue weight, lipid profiles and expression of some gene control lipid metabolism. Material and methods 20 female CD-1 mice at 5 weeks age were divided into two groups, one served as control and the second received 10% of gum arabic in drinking water for 6 weeks. Liver and visceral adipose tissue and serum were collected from all groups. Total cholesterol, triglyceride, HDL-c and LDL-c were assayed using kits, and the expression of lipid metabolic enzyme gene was detected by RT-PCR. Results and discussion The results showed that gum arabic significantly decreased body weight ( P P P P P Conclusions The results conclude that gum arabic can reduce body weight and visceral adipose tissue weight, and down-regulated PPAR-γ and SCD gene expression.

Effects of two whole-grain barley varieties on caecal SCFA, gut microbiota and plasma inflammatory markers in rats consuming low- and high-fat diets

Mixed-linkage β-glucans are fermented by the colon microbiota that give rise to SCFA. Propionic and butyric acids have been found to play an important role in colonic health, as well as they may have extraintestinal metabolic effects. The aim of the present study was to investigate how two whole-grain barley varieties differing in dietary fibre and β-glucan content affected caecal SCFA, gut microbiota and some plasma inflammatory markers in rats consuming low-fat (LF) or high-fat (HF) diets. Barley increased the caecal pool of SCFA in rats fed the LF and HF diets compared with those fed the control diet, and the effect was generally dependent on fibre content, an exception was butyric acid in the LF setting. Furthermore, whole-grain barley reduced plasma lipopolysaccharide-binding protein and monocyte chemoattractant protein-1, increased the caecal abundance of Lactobacillus and decreased the Bacteroides fragilis group, but increased the number of Bifidobacterium only when dietary fat was consumed at a low level. Fat content influenced the effects of barley: rats fed the HF diets had a higher caecal pool of acetic and propionic acids, higher concentrations of amino acids and higher amounts of lipids in the portal plasma and liver than rats fed the LF diets; however, less amounts of butyric acid were generally formed. Interestingly, there was an increase in the caecal abundance of Akkermansia and the caecal pool of succinic acid, and a decrease in the proportion of Bifidobacterium and the Clostridium leptum group. In summary, whole-grain barley decreased HF diet-induced inflammation, which was possibly related to the formation of SCFA and changes in microbiota composition. High β-glucan content in the diet was associated with reduced plasma cholesterol levels.

Apolipoprotein AI deficiency inhibits serum opacity factor activity against plasma high density lipoprotein via a stabilization mechanism.

The reaction of Streptococcal serum opacity factor (SOF) against plasma high-density lipoproteins (HDL) produces a large cholesteryl ester-rich microemulsion (CERM), a smaller neo HDL that is apolipoprotein (apo) AI-poor, and lipid-free apo AI. SOF is active versus both human and mouse plasma HDL. In vivo injection of SOF into mice reduces plasma cholesterol ∼40% in 3 h while forming the same products observed in vitro, but at different ratios. Previous studies supported the hypothesis that labile apo AI is required for the SOF reaction vs HDL. Here we further tested that hypothesis by studies of SOF against HDL from apo AI-null mice. When injected into apo AI-null mice, SOF reduced plasma cholesterol ∼35% in 3 h. The reaction of SOF vs apo AI-null HDL in vitro produced a CERM and neo HDL, but no lipid-free apo. Moreover, according to the rate of CERM formation, the extent and rate of the SOF reaction versus apo AI-null mouse HDL were less than that against wild-type (WT) mouse HDL. Chaotropic perturbation studies using guanidine hydrochloride showed that apo AI-null HDL was more stable than WT HDL. Human apo AI added to apo AI-null HDL was quantitatively incorporated, giving reconstituted HDL. Both SOF and guanidine hydrochloride displaced apo AI from the reconstituted HDL. These results support the conclusion that apo AI-null HDL is more stable than WT HDL because it lacks apo AI, a labile protein that is readily displaced by physicochemical and biochemical perturbations. Thus, apo AI-null HDL is less SOF-reactive than WT HDL. The properties of apo AI-null HDL can be partially restored to those of WT HDL by the spontaneous incorporation of human apo AI. It remains to be determined what other HDL functions are affected by apo AI deletion.

Plant sterols for adults with hypercholesterolemia treated with or without medication (statins)

Hypercholesterolemia is the most common coronary risk factor among the Spanish population; 37.4% of the Spanish adult population have cholesterol levels between 190 and 240 mg/dl. Foods enriched with plant sterols (PS) can effectively reduce plasma cholesterol in patients with high levels. However, its effectiveness and safety in adults with moderate hypercholesterolemia who are on medication (statins) or not has been less studied. The aim of this review is to establish the possible role of plant sterols in the control of hypercholesterolemia, as well as how safe they are for people with moderate hypercholesterolemia treated with statins. The main studies were looked at, regardless of design, language or publication date which studied the connection between “plant sterols” and “hypercholesterolemia”, using Pubmed/Medline, SCOPUS and Google Scholar databases. The studies brought together in this review show that an intake of between 2 and 3g/day of plant sterols effectively reduces plasma cholesterol levels in patients with hypercholesterolemia. Both clinical studies and available meta-analyses do not indicate any problems related to the drug-nutrient interaction associated with the use of plant sterol-enriched foods. In patients with moderate hypercholesterolemia where the use of statins is not justified a healthy diet, exercise and foods high in PS can provide the best therapeutic approach.

Novel method for reducing plasma cholesterol: a ligand replacement therapy.

Despite wide use of statins, significant cardiovascular disease risk persists. High-density lipoprotein based therapy has not yielded any positive results in combating this disease. Newer methods to rapidly decrease plasma cholesterol are much needed. While apolipoprotein B is a ligand for low-density lipoprotein receptor, which clears low-density lipoprotein cholesterol in a highly regulated pathway, apolipoprotein E (apoE) is a ligand for clearing other apolipoprotein B containing atherogenic lipoproteins via an alternate receptor pathway, especially the heparin sulfate proteoglycans on the liver cell surface. We describe here a novel method that replaces apoE as a ligand to clear all of the atherogenic lipoproteins via the heparin sulfate proteoglycans pathway. This ligand replacement apoE mimetic peptide therapy, having been designated as an orphan drug by the US FDA, is in clinical trials.

Mechanisms of cholesterol and saturated fatty acid lowering by Quillaja saponaria extract, studied by in vitro digestion model.

Quillaja saponin extracts are known to reduce plasma cholesterol levels in humans. Here we study the mechanism of this effect with Quillaja Dry saponin extract (QD). In vitro model of triglyceride lipolysis is used to quantify the effect of QD on the solubilization of cholesterol and of the lipolysis products (fatty acids and monoglycerides) in the dietary mixed micelles (DMM). We found that QD extract decreases significantly both the cholesterol (from 80% to 20%) and saturated fatty acids (SFA, from 70% to 10%) solubilised in DMM. Series of dedicated experiments prove that QD may act by two mechanisms: (1) direct precipitation of cholesterol and (2) displacement of cholesterol from the DMM. Both mechanisms lead to increased cholesterol precipitation and, thus, render cholesterol bio-inaccessible. We prove also that the saponin molecules are not the active component of QD, because highly purified Quillaja extract with very similar saponin composition does not exhibit cholesterol-lowering or SFA-lowering effect. The effect of QD extract on cholesterol solubilisation is most probably caused by the high-molecular weight polyphenol molecules, present in this extract. The reduced SFA solubilisation is caused by Ca(2+) ions of relatively high concentration (1.25 wt%), also present in QD extract, which precipitate the fatty acids into calcium soaps.