Advances in experimental dyslipidemia and atherosclerosis

Neuroprotective aftermath of Monodora myristica and Glycyrrhiza glabra against cassava diet containing vacuum gas oil induced brain injury in Wistar rats

Vacuum gas oil (VGO) is a hydrocarbon combination formed during crude oil extraction, and its consumption may have neurological repercussions. This study investigated the neuroprotective properties of Monodora myristica and Glycyrrhiza glabra in rats given cassava flour diet containing vacuum gas oil (CFD-VGO). Thirty rats were separated into six groups and treated as follows: Group 1 severed as normal control. Group 2 were fed CFD-VGO only. After a normal diet was given to groups 3, 4, and 5, M. myristica, G. glabra, and M. myristica plus G. glabra extracts were administered. Group 6, 7, 8 and 9 were given CFD-VGO and then treated with M. myristica extract, G. glabra extract, M. myristica plus G. glabra extracts and 2-methyl cellulose respectively. The rats were euthanized using carbon dioxide after experimental period of 28 days. The brain was excised for biochemical assays. The results showed that the concentration of the assessed 16 PAHs in CFD-VGO using GC-MS was 53.38 ppm. Significant (p < 0.05) increase were observed in malondialdehyde (MDA), total cholesterol (T.Chl), triacylglycerol (TAG), low density lipoprotein-cholesterol (LDL-C), and decrease in high density lipoprotein-cholesterol (HDL-C), acetylcholinesterase (AChE) and ATPases in the brain rats fed with CFD-VGO. On the other hand, administration of M. myristica and G. glabra extract effectively restored altered antioxidants, ATPases, and lipids in brain of rats fed with cassava diet containing VGO.

Investigating pigeon circovirus infection in a pigeon farm: molecular detection, phylogenetic analysis and complete genome analysis

BACKGROUND

Pigeon circovirus infections in pigeons (Columba livia domestica) have been reported worldwide. Pigeons should be PiCV-free when utilized as qualified experimental animals. However, pigeons can be freely purchased as experimental animals without any clear guidelines to follow. Herein, we investigated the status quo of PiCV infections on a pigeon farm in Beijing, China, which provides pigeons for experimental use.

RESULTS

PiCV infection was verified in at least three types of tissues in all forty pigeons tested. A total of 29 full-length genomes were obtained and deposited in GenBank. The whole genome sequence comparison among the 29 identified PiCV strains revealed nucleotide homologies of 85.8-100%, and these sequences exhibited nucleotide homologies of 82.7-98.9% as compared with those of the reference sequences. The cap gene displayed genetic diversity, with a wide range of amino acid homologies ranging from 64.5% to 100%. Phylogenetic analysis of the 29 full-genome sequences revealed that the PiCV strains in this study could be further divided into four clades: A (17.2%), B (10.4%), C (37.9%) and D (34.5%). Thirteen recombination events were also detected in 18 out of the 29 PiCV genomes obtained in this study. Phylogenetic research using the rep and cap genes verified the recombination events, which occurred between clades A/F, A/B, C/D, and B/D among the 18 PiCV strains studied.

CONCLUSIONS

In conclusion, PiCV infection, which is highly genetically varied, is extremely widespread on pigeon farms in Beijing. These findings indicate that if pigeons are to be used as experimental animals, it is necessary to evaluate the impact of PiCV infection on the results.

Comparative study of dietary fat: lard and sugar as a better obesity and metabolic syndrome mice model

BACKGROUND

Diet macronutrient heterogeneity hinders animal studies' data extrapolation from metabolic disorders to human diseases.

OBJECTIVE

The present study aimed to evaluate different fat-diet compositions' effect on inducing lipid/glucose metabolism alterations in mice.

METHODS

Swiss male mice were fed for 12 weeks with five different diets: Standard Diet (ST), American Institute of Nutrition 93 for growth (AIN93G) high-butter/high-sugar (HBHS), high-lard/high-sugar (HLHS), and high-oil/high-sugar diet (soybean oil) (HOHS). Several parameters, such as serum biochemistry, histology, and liver mRNA expression, were accessed.

RESULTS

The main findings revealed that the HLHS diet dramatically altered liver metabolism inducing hepatic steatosis and increased total cholesterol, triglycerides, VLDL, increasing liver CCAAT/enhancer binding protein (CEBP-α), Acetyl-CoA carboxylase (ACC) and Catalase (CAT) mRNA expression. Moreover, the HLHS diet increased glucose intolerance and reduced insulin sensitivity.

CONCLUSIONS

High-fat/high-sugar diets are efficient to induce obesity and metabolic syndrome-associated alterations, and diets enriched with lard and sugar showed more effective results.

Atheroprotective Effects and Mechanisms of Postmarketing Chinese Patent Formulas in Atherosclerosis Models: A Systematic Review

BACKGROUND

Some postmarketing Chinese patent formulas have been widely used to treat atherosclerosis (AS) and play critical roles in Chinese healthcare. However, the usage of these herbs is yet controversial due to unclear effects and lack of understanding of the mechanism of action. With the modernization of traditional Chinese formulas, we are to elucidate the atheroprotective properties of these remedies from successful postmarketing experiments in vivo.

METHODS

In this systematic review, we critically searched the databases, applied stringent criteria, assessed the methodological quality, and examined the current evidence in vivo.

RESULTS

Consequently, 60 studies were included in the present qualitative synthesis. Data on models, high-fat diet, intervention time, outcome measures, efficacy, and mechanisms were collected. Finally, 23 formulas that could alleviate AS were correlated to the amelioration of plaques, improvement of plaque stability, modification of lipid level and lipid metabolism, and the effects of anti-inflammation and antioxidant stress with multiple components and targets. However, the methodological quality was low and incomplete among the included literature.

CONCLUSIONS

Thus, taken together, the studies on postmarketing Chinese patent formulas would provide a novel approach to improve the treatment of AS, and rigorously designed studies would provide high-quality evidence.

All-trans-retinoic acid ameliorates atherosclerosis, promotes perivascular adipose tissue browning, and increases adiponectin production in Apo-E mice

All-trans-retinoic acid (atRA), an active metabolite of vitamin A, exerts a potential role in the prevention of cardiovascular diseases. It has been shown that atRA ameliorates atherosclerosis while the exact mechanism underlying this protection remains unknown. This study investigated the influence of atRA on insulin resistance (IR), atherosclerosis, and the process of perivascular adipose tissue (PVAT) browning. Moreover, syntheses of adiponectin, adipokine with anti-atherogenic effects, and tumor necrosis factor-alpha (TNF-α), a pro-inflammatory cytokine, were determined in PVAT. Apolipoprotein E-deficient mice (Apo-E) and control C57BL/6J wild-type mice were treated with atRA (5 mg/kg/day) or vehicle (corn oil) by plastic feeding tubes for 8 weeks. Long-term atRA treatment in Apo-E mice did not affect insulin resistance. AtRa administration ameliorated atherosclerosis, induced PVAT browning, and increased adiponectin production in PVAT in Apo-E mice. Furthermore, atRA increased nitric oxide (NO) level but did not affect adiponectin concentration in the aorta of Apo-E mice. These results indicate that atRA ameliorates atherosclerosis in Apo-E mice. We also observed the browning of PVAT. Besides, atRA increased the synthesis of adiponectin in PVAT and augmented NO level in the aorta in ApoE mice.

Cerebral arterial architectonics and CFD simulation in mice with type 1 diabetes mellitus of different duration

Type 1 diabetes is a chronic autoimmune disease that affects tens of millions of people. Diabetes mellitus is one of the strongest factors in the development of cerebrovascular diseases. In this study we used NOD.CB17 Prkdcscid mice and the pharmacological model of type 1 diabetes mellitus of different duration to study changes in the cerebral vasculature. We used two combined approaches using magnetic resonance angiography both steady and transient CFD blood flow modeling. We identified the influence of type 1 diabetes on the architectonics and hemodynamics of the large blood vessels of the brain as the disease progresses. For the first time, we detected a statistically significant change in angioarchitectonics (the angles between the vessels of the circle of Willis, cross-sections areas of vessels) and hemodynamic (maximum blood flow rate, hydraulic resistance) in animals with diabetes duration of 2 months, that is manifested by the development of asymmetry of cerebral blood flow. The result shows the negative effect of diabetes on cerebral circulation as well as the practicability of CFD modeling. This may be of extensive interest, in pharmacological and preclinical studies.

Innovators in atherosclerosis research: A historical review

This review presents a retrospective analysis of the significance of the contributions of pathologists and kindred investigators in the latter half of the twentieth century to the advancement of understanding of atherosclerosis, a major disease and affliction of humankind. These outstanding investigators contributed importantly to the development of a large body of evidence encompassing population-based autopsy studies, experimental animal studies and cell biological investigations that, coupled with insights from epidemiological studies, serve as the underpinning for the current dominant response to injury theory of atherogenesis. Their collective contributions have been highly meritorious and will remain seminally important into the future.

Precision nanomedicine in atherosclerosis therapy: how far are we from reality?

Atherosclerosis, characterized by build-up of lipids and chronic inflammation of the arterial wall, is the primary cause of cardiovascular disease and is a leading cause of death worldwide. Currently available therapies are inadequate and warrant the demand for improved technologies for more effective treatment. Although primarily the domain of antitumor therapy, recent advances have shown the considerable potential of nanomedicine to advance atherosclerosis treatment. This Review details the arsenal of nanocarriers and molecules available for selective targeting in atherosclerosis, and emphasize the challenges in atherosclerosis treatment.

Eicosapentaenoic acid in the form of phospholipids exerts superior anti-atherosclerosis effects to its triglyceride form in ApoE−/−mice

EPA-PL was superior to EPA-TG in reducing lesion progression by modulating hepatic lipid metabolism and decreasing inflammation in the artery wall and circulatory system, which might be attributed to the structural differences at the sn-3 position.

Biochemical and Ultrastructural Cardiac Changes Induced by High-Fat Diet in Female and Male Prepubertal Rabbits

Early weight gain induced by high-fat diet has been identified as a predictor for cardiac disease, one of the most serious public health problems. Our goal is to study the influence of a HFD on biochemical, oxidant stress parameters, and the cardiac ultrastructure in both male and female prepubertal models. Experiments were carried on 24 prepubertal New Zealand white rabbits, randomly assigned to male and female control (MC and FC, resp.) or HFD (MHFD and FHFD, resp.) groups (n = 6) for 3 months. Body and heart weights and some biochemical and oxidative stress parameters such as lipids, calcium, CKMB, MDA, uric acid, ascorbic acid, and AOA are evaluated in plasma and the left ventricle. Under HFD effect, plasma parameters, such as lipids (TL, PL, and LDL-C), MDA, and CK-MB, increase more significantly in male than in female groups, when AA decreases. Some cardiac parameters such as TG and UA increase, when AA and AOA decrease; these variations are more significant in FHFD. In both male and female rabbits, HFD caused changes in heart ultrastructure, junctional complexes, mitochondria size and form, and so on. Early HFD feeding induced overweight, oxidative stress, and metabolic alterations in plasma and the heart of prepubertal rabbits, whereas lipotoxicity has especially a negative impact on male plasma but affects more the female heart ultrastructure.

Peptide Amphiphile Nanostructures for Targeting of Atherosclerotic Plaque and Drug Delivery

Co-assembled peptide amphiphile nanofibers designed to target atherosclerotic plaque and enhance cholesterol efflux are shown to encapsulate and deliver a liver X receptor agonist to increase efflux from murine macrophages in vitro. Fluorescence microscopy reveals that the nanofibers, which display an apolipoprotein-mimetic peptide, localize at plaque sites in LDL receptor knockout mice with or without the encapsulated molecule, while nanofibers displaying a scrambled, non-targeting peptide sequence do not demonstrate comparable binding. These results show that nanofibers functionalized with apolipoprotein-mimetic peptides may be effective vehicles for intravascular targeted drug delivery to treat atherosclerosis.

Ginsenoside Rb1 for Myocardial Ischemia/Reperfusion Injury: Preclinical Evidence and Possible Mechanisms

Ginseng is an important herbal drug that has been used worldwide for many years. Ginsenoside Rb1 (G-Rb1), the major pharmacological extract from ginseng, possesses a variety of biological activities in the cardiovascular systems. Here, we conducted a preclinical systematic review to investigate the efficacy of G-Rb1 for animal models of myocardial ischemia/reperfusion injury and its possible mechanisms. Ten studies involving 211 animals were identified by searching 6 databases from inception to May 2017. The methodological quality was assessed by using the CAMARADES 10-item checklist. All the data were analyzed using RevMan 5.3 software. As a result, the score of study quality ranged from 3 to 7 points. Meta-analyses showed that G-Rb1 can significantly decrease the myocardial infarct size and cardiac enzymes (including lactate dehydrogenase, creatine kinase, and creatine kinase-MB) when compared with control group (P < 0.01). Significant decrease in cardiac troponin T and improvement in the degree of ST-segment depression were reported in one study (P < 0.05). Additionally, the possible mechanisms of G-Rb1 for myocardial infarction are antioxidant, anti-inflammatory, antiapoptosis, promoting angiogenesis and improving the circulation. Thus, G-Rb1 is a potential cardioprotective candidate for further clinical trials of myocardial infarction.

Responsiveness of Coronary Arteries to Nitroglycerin under Hypoxia: The Importance of the Endothelium

<b><i>Background/Aims:</i></b> Nitroglycerin is widely used as a coronary vasodilator in the treatment of ischemic heart diseases. This study investigated the influence of hypoxia on nitroglycerin-induced relaxation in endothelium-intact and -denuded rabbit, monkey, and porcine coronary arteries. <b><i>Methods:</i></b> Helically cut strips of coronary arteries were suspended in organ chambers, and isometric tension was recorded. <b><i>Results:</i></b> Nitroglycerin concentration dependently relaxed endothelium-intact rabbit coronary arteries, which were not different under normoxic and hypoxic conditions. On the other hand, nitroglycerin-induced relaxation of endothelium-denuded arteries was significantly attenuated by hypoxia. Similarly, the relaxant response of endothelium-intact monkey coronary arteries to nitroglycerin was not affected by hypoxia, whereas that of endothelium-denuded arteries was impaired. As is the case with rabbit and monkey coronary arteries, exposure to hypoxia resulted in impaired relaxation by nitroglycerin in endothelium-denuded but not endothelium-intact porcine coronary arteries. <b><i>Conclusion:</i></b> These findings suggest that coronary endothelium plays a pivotal role in preventing the hypoxia-induced impairment of nitroglycerin responsiveness, regardless of the animal species.

Large animal models of cardiovascular disease

The human cardiovascular system is a complex arrangement of specialized structures with distinct functions. The molecular landscape, including the genome, transcriptome and proteome, is pivotal to the biological complexity of both normal and abnormal mammalian processes. Despite our advancing knowledge and understanding of cardiovascular disease (CVD) through the principal use of rodent models, this continues to be an increasing issue in today's world. For instance, as the ageing population increases, so does the incidence of heart valve dysfunction. This may be because of changes in molecular composition and structure of the extracellular matrix, or from the pathological process of vascular calcification in which bone-formation related factors cause ectopic mineralization. However, significant differences between mice and men exist in terms of cardiovascular anatomy, physiology and pathology. In contrast, large animal models can show considerably greater similarity to humans. Furthermore, precise and efficient genome editing techniques enable the generation of tailored models for translational research. These novel systems provide a huge potential for large animal models to investigate the regulatory factors and molecular pathways that contribute to CVD in vivo. In turn, this will help bridge the gap between basic science and clinical applications by facilitating the refinement of therapies for cardiovascular disease.

Effect of Silybin on Lipid Profile in Hypercholesterolaemic Rats

INTRODUCTION

Hyperlipidemia is a major cause of atherosclerosis and atherosclerosis associated conditions, such as Coronary Heart Disease (CHD), ischaemic cerebrovascular disease and peripheral vascular disease. Though there are hypolipidemic drugs available, the search for a more efficacious hypo lipidemic agent was always going on.

AIM

To study the effect of Silybin on lipid profile in Hypercholesterolaemic rats.

MATERIALS AND METHODS

After grant of permission from animal ethics committee, the animals were divided into four groups of eight each (normal control, Experimental control with High cholesterol diet, High cholesterol diet + Silybin 300mg, High cholesterol diet + Silybin 600mg). At the end of 60 days the animals in all the groups were subjected to overnight fasting followed by plasma and liver biochemical analyses.

STATISTICAL ANALYSIS

The data were analysed by ANNOVA followed by Duncan's multi range test and the value of p≤0.05 was used as the criterion for statistical significance.

RESULTS

The rats fed on high cholesterol diet showed significant increase in serum total cholesterol, Triglycerides, LDL-C and VLDL-C. Treatment with Silybin significantly decreased serum total cholesterol (24%), Triglycerides (21%), LDL-C (24%) in a dose dependent manner. Rats treated with Silybin (300 and 600 mg/kg) showed significant increase in hepatic HDL -C and decrease in other lipid profiles.

CONCLUSION

Treatment with Silybin significantly decreased both serum and hepatic total cholesterol, triglycerides, VLDL-C, LDL-C and increased HDL-C at both doses.

A Comparative Study of Lipid-Lowering Effects of Guggul and Atorvastatin Monotherapy in Comparison to Their Combination in High Cholesterol Diet-Induced Hyperlipidemia in Rabbits

BACKGROUND

Hypolipidemic activity of gugulipid has been widely described in traditional literature.

OBJECTIVE

This study was done to evaluate hypolipidemic activity of guggul and atorvaststin monotherapy in comparison to their combination in rabbits.

MATERIALS AND METHODS

Male New Zealand White rabbits (body weight 1.3-1.8 kg and age 8-10 weeks) were made hyperlipidemic by feeding cholesterol (0.5 g/kg) for three weeks and randomly divided into a control and three treatment groups receiving: atorvastatin (3.7 mg/kg), guggul (3.5 mg/kg) and their combination (same dose) for the next three weeks. Body weight measurements, estimation of serum lipid profile were done at the beginning, after three and six weeks, respectively. Histopathological examination of liver, heart and aorta was done after six weeks. Statistical analysis was done with SPSS version 16.0 using one-way and repeated measures analysis of variance (ANOVA) followed by post-hoc multiple comparison test with two tailed P value < 0.05 as significant.

RESULTS

All treated groups had significant reduction in cholesterol, triglyceride, low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) in comparison to pre-treatment values and control group, and had significant increase in high-density lipoprotein (HDL) in comparison to pre-treatment values.

CONCLUSION

Combination of atorvastatin and guggul was comparable to their monotherapies in improving lipid profile.

Regulation effect of Aspirin Eugenol Ester on blood lipids in Wistar rats with hyperlipidemia

Background

Aspirin eugenol ester (AEE) is a promising drug candidate for treatment of inflammation, pain and fever and prevention of cardiovascular diseases with less side effects. The experiment will be conducted to investigate the efficacy of AEE on curing hyperlipidemia in Wistar rats. The rats were fed with high fat diet (HFD) for 8 weeks to induce hyperlipidemia.

Results

Compared with the model group, the results showed that AEE at 54 mg/kg dosage could significantly decrease the hyperlipidemia indexes including triglyceride (TG), low density lipoprotein (LDL) and total cholesterol (TCH) (p < 0.01), increase high density lipoprotein (HDL) (p < 0.05) for five weeks drug administration. Meanwhile, simvastatin had same effect on hyperlipidemia indexes such as TG, LDL, TC, but no significant increase in HDL.

Conclusion

AEE was effective against hyperlipidemia and had better anti-hyperlipidemic effect than its component, acetylsalicylic acid (Aspirin, ASA), eugenol and integration of ASA and eugenol. Under the experimental circumstance, the optimal dose of AEE to cure hyperlipidemia is 54 mg/kg for five weeks in Wistar rats.

Development of Antiatherosclerotic Drugs on the basis of Natural Products Using Cell Model Approach

Atherosclerosis including its subclinical form is one of the key medical and social problems. At present, there is no therapy available for widespread use against subclinical atherosclerosis. The use of synthetic drugs for the prevention of arteriosclerosis in its early stages is not sufficient because of the limited indications for severe side effects and high cost of treatment. Obviously, effective antiatherosclerotic drugs based on natural products would be a preferred alternative. Simple cell-based models for testing different natural products have been developed and the ability of natural products to prevent intracellular lipid accumulation in primary cell culture was evaluated. This approach utilizing cell models allowed to test effects of such direct antiatherosclerotic therapy, analyzing the effects mimicking those which can occur "at the level" of arterial wall via the inhibition of intracellular lipid deposition. The data from the carried out clinical trials support a point of view that the identification of antiatherosclerotic activity of natural products might offer a great opportunity for the prevention and treatment of atherosclerotic disease, reducing cardiovascular morbidity and mortality.

Animal Models in Cardiovascular Research: Hypertension and Atherosclerosis

Hypertension and atherosclerosis are among the most common causes of mortality in both developed and developing countries. Experimental animal models of hypertension and atherosclerosis have become a valuable tool for providing information on etiology, pathophysiology, and complications of the disease and on the efficacy and mechanism of action of various drugs and compounds used in treatment. An animal model has been developed to study hypertension and atherosclerosis for several reasons. Compared to human models, an animal model is easily manageable, as compounding effects of dietary and environmental factors can be controlled. Blood vessels and cardiac tissue samples can be taken for detailed experimental and biomolecular examination. Choice of animal model is often determined by the research aim, as well as financial and technical factors. A thorough understanding of the animal models used and complete analysis must be validated so that the data can be extrapolated to humans. In conclusion, animal models for hypertension and atherosclerosis are invaluable in improving our understanding of cardiovascular disease and developing new pharmacological therapies.

Considerations on pig models for appetite, metabolic syndrome and obese type 2 diabetes: From food intake to metabolic disease

(Mini)pigs have proven to be a valuable animal model in nutritional, metabolic and cardiovascular research and in some other biomedical research areas (toxicology, neurobiology). The large resemblance of (neuro)anatomy, the gastro-intestinal tract, body size, body composition, and the omnivorous food choice and appetite of the pig are additional reasons to select this large animal species for (preclinical) nutritional and pharmacological studies. Both humans and pigs are prone to the development of obesity and related cardiovascular diseases such as hypertension and atherosclerosis. Bad cholesterol (LDL) is high and good cholesterol (HDL) is low in pigs, like in humans. Disease-relevant pig models fill the gap between rodent models and primate species including humans. Diet-induced obese pigs show a phenotype related to the metabolic syndrome including high amounts of visceral fat, fatty organs, insulin resistance and high blood pressure. However, overt hyperglycaemia does not develop within 6 months after initiation of high sugar-fat feeding. Therefore, to accelerate the induction of obese type 2 diabetes, obese pigs can be titrated with streptozotocin, a chemical agent which selectively damages the insulin-producing pancreatic beta-cells. However, insulin is required to maintain obesity. With proper titration of streptozotocin, insulin secretion can be restrained at such a level that hyperglycaemia will be induced but lipolysis is still inhibited due to the fact that inhibition of lipolysis is more sensitive to insulin compared to stimulation of glucose uptake. This strategy may lead to a stable hyperglycaemic, non-ketotic obese pig model which remains anabolic with time without the necessity of exogenous insulin treatment.

Effect of low carbohydrate high protein (LCHP) diet on lipid metabolism, liver and kidney function in rats

The objective of this study was to compare effects of Western diet (WD) with low carbohydrate high protein (LCHP) diet on lipid metabolism, liver and kidney function in rats. Eighteen rats were randomly assigned to three experimental groups and fed for the next 2 months. The experimental diets were: Control (7% of soybean oil, 20% protein), WD (21% of butter, 20% protein), and LCHP (21% of butter and 52.4% protein) diet. The LCHP diet significantly decreased the body weight of the rats. Diet consumption was differentiated among groups, however significant changes were observed since third week of the experiment duration. Rats fed LCHP diet ate significantly less (25.2g/animal/day) than those from Control (30.2g/animal/day) and WD (27.8 g/animal/day) groups. Additionally, food efficiency ratio (FER) tended to decrease in LCHP fed rats. Serum homocysteine concentration significantly decreased in rats fed WD and LCHP diets. Liver weights were significantly higher in rats fed WD and LCHP diets. At the end of the experiment (2 months) the triacylglycerol (TAG) was significantly decreased in animals fed LCHP compared to WD. qRT-PCR showed that SCD-1 and FAS were decreased in LCHP fed rats, but WD diet increased expression of lipid metabolism genes. Rats receiving LCHP diet had two fold higher kidney weight and 54.5% higher creatinin level compared to Control and WD diets. In conclusion, LCHP diet decreased animal's body weight and decreased TAG in rat's serum. However, kidney damage in LCHP rats was observed.

The pigeon (Columba livia) model of spontaneous atherosclerosis

Multiple animal models have been employed to study human atherosclerosis, the principal cause of mortality in the United States. Each model has individual advantages related to specific pathologies. Initiation, the earliest disease phase, is best modeled by the White Carneau (WC-As) pigeon. Atherosclerosis develops spontaneously in the WC-As without either external manipulation or known risk factors. Furthermore, susceptibility is caused by a single gene defect inherited in an autosomal recessive manner. The Show Racer (SR-Ar) pigeon is resistant to atherosclerosis. Breed differences in the biochemistry and metabolism of celiac foci cells have been described. For example, WC-As have lower oxidative metabolism but higher amounts of chondroitin-6-sulfate and nonesterified fatty acids compared with SR-Ar. Gene expression in aortic smooth muscle cells was compared between breeds using representational difference analysis and microarray analysis. Energy metabolism and cellular phenotype were the chief gene expression differences. Glycolysis and synthetic cell types were related to the WC-As but oxidative metabolism and contractile cell types were related to the SR-Ar. Rosiglitazone, a PPARγ agonist, blocked RNA binding motif (RBMS1) expression in WC-As cells. The drug may act through the c-myc oncogene as RBMS1 is a c-myc target. Proteomic tests of aortic smooth muscle cells supported greater glycosylation in the WC-As and a transforming growth factor β effect in SR-Ar. Unoxidized fatty acids build up in WC-As cells because of their metabolic deficiency, ultimately preventing the contractile phenotype in these cells. The single gene responsible for the disease is likely regulatory in nature.

Most appropriate animal models to study the efficacy of statins: a systematic review

BACKGROUND

In animal models and clinical trials, statins are reported as effective in reducing cholesterol levels and lowering the risk of cardiovascular diseases. We have aggregated the findings in animal models - mice, rats and rabbits - using the technique of systematic review and meta-analysis to highlight differences in the efficacy of statins.

MATERIALS AND METHODS

We searched Medline and Embase. After examining all eligible articles, we extracted results about total cholesterol and other blood parameters, blood pressure, myocardial infarction and survival. Weighted and standard mean difference random effects meta-analysis was used to measure overall efficacy in prespecified species, strains and subgroups.

RESULTS

We included in systematic review 161 animal studies and we analysed 120 studies, accounting for 2432 animals. Statins lowered the total cholesterol across all species, although with large differences in the effect size: -30% in rabbits, -20% in mice and -10% in rats. The reduction was larger in animals fed on a high-cholesterol diet. Statins reduced infarct volume but did not consistently reduce the blood pressure or effect the overall survival. Few studies considered strains at high risk of cardiovascular diseases or hard outcomes.

CONCLUSIONS

Although statins showed substantial efficacy in animal models, few preclinical data considered conditions mimicking human pathologies for which the drugs are clinically indicated and utilized. The empirical finding that statins are more effective in lowering cholesterol derived from an external source (i.e. diet) conflicts with statin's supposed primary mechanism of action.

Animal models of atherosclerosis and magnetic resonance imaging for monitoring plaque progression

Atherosclerosis, the main cause of heart attack and stroke, is the leading cause of death in most modern countries. Preventing clinical events depends on a better understanding of the mechanism of atherosclerotic plaque destabilization. Our knowledge on the characteristics of vulnerable plaques in humans has grown past decades. Histological studies have provided a precise definition of high-risk lesions and novel imaging methods for human atherosclerotic plaque characterization have made significant progress. However the pathological mechanisms leading from stable lesions to the formation of vulnerable plaques remain uncertain and the related clinical events are unpredictable. An animal model mimicking human plaque destablization is required as well as an in vivo imaging method to assess and monitor atherosclerosis progression. Magnetic resonance imaging (MRI) is increasingly used for in vivo assessment of atherosclerotic plaques in the human carotids. MRI provides well-characterized morphological and functional features of human atherosclerotic plaque which can be also assessed in animal models. This review summarizes the most common species used as animal models for experimental atherosclerosis, the techniques to induce atherosclerosis and to obtain vulnerable plaques, together with the role of MRI for monitoring atherosclerotic plaques in animals.

Rosiglitazone modulates pigeon atherosclerotic lipid accumulation and gene expression in vitro

Atherosclerosis is a major contributor to the overall United States mortality rate, primarily in the form of heart attacks and stroke. Unlike the human disease, which is believed to be multifactorial, pigeon atherosclerosis is due to a single gene autosomal recessive trait. The White Carneau (WC-As) strain develops atherosclerotic plaques without the presence of known environmental risk factors such as diet and classic predictors such as blood pressure or blood cholesterol levels. With similar parameters, the Show Racer (SR-Ar) is resistant to plaque development. Thiazolidinediones, including rosiglitazone, activate the peroxisome proliferator-activated receptor gamma (PPARγ) raising cellular sensitivity to insulin. The effect of rosiglitazone was evaluated in aortic smooth muscle cells (SMC) from these 2 pigeon breeds. Primary SMC cultures were prepared from WC-As and SR-Ar squabs. Cell monolayers, which achieved confluence in 7 d, were treated with 0 or 4 µM rosiglitazone for 24 h. Cellular lipid accumulation was evaluated by oil red O staining. Control WC-As cells had significantly higher vacuole scores and lipid content than did the SR-Ar control cells. Rosiglitazone treatment decreased WC-As lipid vacuoles significantly compared with the control cells. On the other hand, lipid vacuoles in the treated and untreated SR-Ar cells did not differ significantly. The effect of rosiglitazone on WC-As SMC gene expression was compared with control SMC using representational difference analysis. Significant transcript increases were found for caveolin and RNA binding motif in the control cells compared with the rosiglitazone-treated cells as well as cytochrome p450 family 17 subfamily A polypeptide 1 (CYP171A) in the rosiglitazone-treated cells compared with the control cells. Although rosiglitazone was selected for these experiments because of its role as a PPARγ agonist, it appears that the drug also tempers c-myc expression, as genes related to this second transcription factor were differentially expressed. Both PPARγ and c-myc appear to affect WC-As SMC gene expression, which may relate to disease development, progression, or both.

Animal models of atherosclerosis

In this mini-review several commonly used animal models of atherosclerosis have been discussed. Among them, emphasis has been made on mice, rabbits, pigs and non-human primates. Although these animal models have played a significant role in our understanding of induction of atherosclerotic lesions, we still lack a reliable animal model for regression of the disease. Researchers have reported several genetically modified and transgenic animal models that replicate human atherosclerosis, however each of current animal models have some limitations. Among these animal models, the apolipoprotein (apo) E-knockout (KO) mice have been used extensively because they develop spontaneous atherosclerosis. Furthermore, atherosclerotic lesions developed in this model depending on experimental design may resemble humans’ stable and unstable atherosclerotic lesions. This mouse model of hypercholesterolemia and atherosclerosis has been also used to investigate the impact of oxidative stress and inflammation on atherogenesis. Low density lipoprotein (LDL)-r-KO mice are a model of human familial hypercholesterolemia. However, unlike apo E-KO mice, the LDL-r-KO mice do not develop spontaneous atherosclerosis. Both apo E-KO and LDL-r-KO mice have been employed to generate other relevant mouse models of cardiovascular disease through breeding strategies. In addition to mice, rabbits have been used extensively particularly to understand the mechanisms of cholesterol-induced atherosclerosis. The present review paper details the characteristics of animal models that are used in atherosclerosis research.

Zebrafish yolk lipid processing: a tractable tool for the study of vertebrate lipid transport and metabolism

Dyslipidemias are a major cause of morbidity and mortality in the world, particularly in developed nations. Investigating lipid and lipoprotein metabolism in experimentally tractable animal models is a crucial step towards understanding and treating human dyslipidemias. The zebrafish, a well-established embryological model, is emerging as a notable system for studies of lipid metabolism. Here, we describe the value of the lecithotrophic, or yolk-metabolizing, stages of the zebrafish as a model for studying lipid metabolism and lipoprotein transport. We demonstrate methods to assay yolk lipid metabolism in embryonic and larval zebrafish. Injection of labeled fatty acids into the zebrafish yolk promotes efficient uptake into the circulation and rapid metabolism. Using a genetic model for abetalipoproteinemia, we show that the uptake of labeled fatty acids into the circulation is dependent on lipoprotein production. Furthermore, we examine the metabolic fate of exogenously delivered fatty acids by assaying their incorporation into complex lipids. Moreover, we demonstrate that this technique is amenable to genetic and pharmacologic studies.

Effects of short-term niacin treatment on plasma lipoprotein concentrations in African green monkeys (Chlorocebus aethiops)

Niacin is the most effective drug available for raising levels of high-density lipoprotein (HDL) cholesterol. To evaluate its effects on plasma lipid concentrations, the authors administered a low dose of niacin to healthy, adult, female African green monkeys for 3 months. In the treated monkeys, low-density lipoprotein cholesterol concentrations decreased by 43% from baseline, whereas concentrations of HDL cholesterol and apolipoprotein A-I increased by 49% and 34%, respectively. The results suggest that in this primate model, a low dose of niacin can effectively increase concentrations of HDL cholesterol.

Atherosclerosis-susceptible and atherosclerosis-resistant pigeon aortic cells express different genes in vivo

Spontaneous atherosclerosis in the White Carneau (WC-As) pigeon is inherited as a single gene disorder, and its progression closely mirrors the human disease. Representational difference analysis and microarray were used to identify genes that were differentially expressed between the susceptible WC-As and resistant Show Racer (SR-Ar) aortic tissue. The RNA extracted from 1-d-old squab aortas was used to make cDNA for each experiment. Fifty-six unique genes were found using representational difference analysis, with 25 exclusively expressed in the WC-As, 15 exclusive to the SR-Ar, and 16 nonexclusive genes having copy number variation between breeds. Caveolin and β-actin were expressed in the WC-As, whereas the proteasome maturation protein and the transcription complex CCR4-NOT were exclusive to the SR-Ar. Microarray analysis revealed 48 genes with differential expression. Vascular endothelial growth factor and p53 binding protein were among the 17 genes upregulated in the WC-As. Thirty-one genes were upregulated in the SR-Ar including the transforming growth factor-β signaling factor SMAD2 and heat shock protein 90. Genes representing several biochemical pathways were distinctly different between breeds. The most striking divergences were in cytoskeletal remodeling, proteasome activity, cellular respiration, and immune response. Actin cytoskeletal remodeling appears to be one of the first differences between susceptible and resistant breeds, lending support to the smooth muscle cell phenotypic reversion hypothesis of human atherogenesis.

Autophagy regulates trans fatty acid-mediated apoptosis in primary cardiac myofibroblasts

Trans fats are not a homogeneous group of molecules and less is known about the cellular effects of individual members of the group. Vaccenic acid (VA) and elaidic acid (EA) are the predominant trans monoenes in ruminant fats and vegetable oil, respectively. Here, we investigated the mechanism of cell death induced by VA and EA on primary rat ventricular myofibroblasts (rVF). The MTT assay demonstrated that both VA and EA (200μM, 0-72 h) reduced cell viability in rVF (P<0.001). The FACS assay confirmed that both VA and EA induced apoptosis in rVF, and this was concomitant with elevation in cleaved caspase-9, -3 and -7, but not caspase-8. VA and EA decreased the expression ratio of Bcl2:Bax, induced Bax translocation to mitochondria and decrease in mitochondrial membrane potential (Δψ). BAX and BAX/BAK silencing in mouse embryonic fibroblasts (MEF) inhibited VA and EA-induced cell death compared to the corresponding wild type cells. Transmission electron microscopy revealed that VA and EA also induced macroautophagosome formation in rVF, and immunoblot analysis confirmed the induction of several autophagy markers: LC3-β lipidation, Atg5-12 accumulation, and increased beclin-1. Finally, deletion of autophagy genes, ATG3 and ATG5 significantly inhibited VA and EA-induced cell death (P<0.001). Our findings show for the first time that trans fat acid (TFA) induces simultaneous apoptosis and autophagy in rVF. Furthermore, TFA-induced autophagy is required for this pro-apoptotic effect. Further studies to address the effect of TFA on the heart may reveal significant translational value for prevention of TFA-linked heart disease.

Edible dry bean consumption (Phaseolus vulgaris L.) modulates cardiovascular risk factors and diet-induced obesity in rats and mice

Pulses are grain legumes that have sustained the civilisations of the world throughout their development; yet this staple food crop has fallen into disuse, particularly in Westernised societies, and decreased consumption parallels increased prevalence of CVD. The objective of the present study was to identify mechanisms that account for the cardioprotective activity of dry bean (Phaseolus vulgaris L.), one of the four primary pulse crops, which is widely produced and consumed globally. Laboratory assays that can be used for in vivo screening of dry beans and other pulses to identify those with the greatest potential to benefit human health are also reported. Sprague–Dawley rats and a diet-induced obesity model in C57Bl/6 mice were used to assess the effect of cooked dry bean incorporated into a purified diet formulation on plasma lipids and hepatic proteins involved in the regulation of lipid biosynthesis. In both animal species, short-term feeding of a bean-containing diet reduced plasma total cholesterol and LDL-cholesterol without affecting HDL-cholesterol or total TAG. Mechanisms associated with cholesterol catabolism and excretion are the likely targets of the bean effect. Unexpectedly, bean-fed obese mice experienced weight loss as well as an improved plasma lipid profile within a 12 d time frame. These findings support the use of short-term (7–14 d) assays to investigate mechanisms that account for the cardioprotective and weight regulatory effects of dry bean and to screen dry bean germplasm resources for types of bean with high protective activity. These same assays can be used to identify the bioactive components of bean that account for the observed effects.

Differentially expressed genes in aortic smooth muscle cells from atherosclerosis-susceptible and atherosclerosis-resistant pigeons

Susceptibility to spontaneous atherosclerosis in the White Carneau (WC-As) pigeon shows autosomal recessive inheritance. Aortic smooth muscle cells (SMC) cultured from susceptible WC-As and resistant Show Racer (SR-Ar) pigeons exhibit developmental and degenerative features corresponding to the respective SMC at atherosclerosis-prone sites in vivo. We used representational difference analysis to identify differentially expressed genes between WC-As and SR-Ar aortic SMC. Total RNA was extracted from cultured primary SMC of each breed, converted to double-stranded cDNA, followed by direct comparison in reciprocal representational difference analysis experiments. Difference products were cloned, sequenced, and identified by BLAST against the chicken genome. Six putative biochemical pathways were distinctly different between breeds with genes involved in energy metabolism and contractility exhibiting the most striking disparity. Genes associated with glycolysis and a synthetic SMC phenotype were expressed in WC-As cells. In contrast, SR-Ar cells expressed genes indicative of oxidative phosphorylation and a contractile SMC phenotype. In WC-As cells, the alternatives of insufficient ATP production limiting contractile function or the lack of functional contractile elements downregulating ATP synthesis cannot be distinguished due to the compressed in vitro versus in vivo developmental time frame. However, the genetic potential for effectively coupling energy production to muscle contraction present in the resistant SR-Ar was lacking in the susceptible WC-As.

Inhibition of hepatic scavenger receptor-class B type I by RNA interference decreases atherosclerosis in rabbits

Objective

Scavenger receptor-class B type I (SR-BI), the receptor for HDL-cholesterol, plays a key role in HDL metabolism, whole body cholesterol homeostasis, and reverse cholesterol transport. We investigated the in vivo impact of hepatic SR-BI inhibition on lipoprotein metabolism and the development of atherosclerosis employing RNA interference.

Methods

Small hairpin RNA plasmid specific for rabbit SR-BI was complexed with galactosylated poly-l-lysine, allowing an organ-selective, receptor-mediated gene transfer. Rabbits were fed a cholesterol-rich diet, and were injected with plasmid-complexes once a week.

Results

After 2 weeks of treatment hepatic SR-BI mRNA levels were reduced by 80% accompanied by reduced SR-BI protein levels and a modulation of the lipoprotein profile. Rabbits treated with SR-BI-specific plasmid-complexes displayed higher cholesteryl ester transfer from HDL to apoB-containing lipoproteins, lower HDL-cholesterol, and higher VLDL-cholesterol levels, when compared to controls. In a long-term study, this gene therapeutic intervention led to a similar modulation of the lipoprotein profile, to lower total cholesterol levels, and most importantly to a 50% reduction of the relative atherosclerotic lesion area.

Conclusion

Our results are another indication that the role of SR-BI in lipoprotein metabolism and atherogenesis in rabbits – a CETP-expressing animal model displaying a manlike lipoprotein profile may be different from the one found in rodents.

Characterization and classification of psittacine atherosclerotic lesions by histopathology, digital image analysis, transmission and scanning electron microscopy

Atherosclerosis is a degenerative and inflammatory vascular disease characterized in mammals and birds by the accumulation of inflammatory cells, lipids, calcium, and formation of large fibrofatty lesions within the intima of arteries resulting in the disorganization of the arterial wall and stenosis of the lumen. Despite the high incidence of atherosclerosis in parrots and the high number of case reports, there are few pathologic investigations and the ultrastructural study of the lesions has not been documented. Sixty-three major arteries were collected from 24 psittacine birds of 11 species during routine post-mortem examinations. Samples from the major arteries were fixed in 2% paraformaldehyde and 1.25% glutaraldehyde, and processed for transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Additional samples were fixed in 10% formalin and embedded in paraffin for histological examination. Additional histochemical stains for calcium, elastic fibres, and lipid were performed. Toluidine blue-stained 0.5 µm-thick resin sections were also obtained. Digital image analysis was performed to provide objective quantitative information on the different lesions. The histopathology and ultrastructure of psittacine atherosclerosis were found to be similar to other avian and mammalian species. Seven lesion types could be described, which were similar to the human classification system. Digital image analysis, TEM, and SEM helped to further describe the lesions and refine the classification system. TEM findings were similar to other avian and mammalian species with the notable presence of macrophage-derived and smooth muscle cell-derived foam cells and extracellular lipid. SEM revealed various stages of endothelial surface defects and, occasionally, adherent blood cells.

Animal models of calcific aortic valve disease

Calcific aortic valve disease (CAVD), once thought to be a degenerative disease, is now recognized to be an active pathobiological process, with chronic inflammation emerging as a predominant, and possibly driving, factor. However, many details of the pathobiological mechanisms of CAVD remain to be described, and new approaches to treat CAVD need to be identified. Animal models are emerging as vital tools to this end, facilitated by the advent of new models and improved understanding of the utility of existing models. In this paper, we summarize and critically appraise current small and large animal models of CAVD, discuss the utility of animal models for priority CAVD research areas, and provide recommendations for future animal model studies of CAVD.

Effect of captopril on serum lipid levels and cardiac mitochondrial oxygen consumption in experimentally-induced hypercholesterolemia in rabbits

Angiotensin converting enzyme inhibitors are widely used in therapy of cardiovascular diseases. However, the consensus on effects of these inhibitors in control of myocardial oxygen consumption during the process of experimental hypercholesterolemia and under the condition of endothelial dysfunction has not been reached. Here we examined effects of captopril, an angiotensin converting enzyme inhibitor, on serum lipid levels and oxygen consumption rate in mitochondria isolated from heart of rabbits treated by hypercholesterolemic diet. During the twelve-week period, the Chinchilla male rabbits were daily treated by saline (controls); 1 % cholesterol diet; 5 mg/kg/day captopril or 1 % cholesterol + 5 mg/kg/day captopril. Total- and high-density lipoprotein cholesterol and triglyceride in serum were measured spectrophotometrically. The left ventricle mitochondrial fraction was isolated and myocardial oxygen consumption was measured by Biological Oxygen Monitor. Mitochondria isolated from hearts of rabbits exposed to hypercholesterolemic diet showed significantly reduced respiration rates (state 3 and state 4) with altering adenosine diphosphate/oxygen ratio, whereas the respiratory control ratio was not affected when compared to controls. Mitochondria from cholesterol/captopril-treated animals showed significantly reduced respiration rates without altering adenosine diphosphate/oxygen ratio index or respiratory control ratio. Although captopril did not exert the favorable effect on serum lipid levels in cholesterol-treated animals, it restored the mitochondrial oxygen consumption. Further studies should be performed to define the underlying physiological and/or pathophysiological mechanisms and clinical implications.

A Diet Rich in Monounsaturated Fatty Acids Improves the Lipid Profile of Mice Previously on a Diet Rich in Saturated Fatty Acids

This study investigated whether switching from a diet rich in saturated fatty acids (SAFAs) to a diet rich in monounsaturated fatty acids (MUFAs) or to one with equal amounts of MUFAs-SAFAs favorably affects the lipid profile of hypercholesterolemic mice. C57BL/6 mice (n = 82) were allocated into 4 groups. The first group (control, n = 10) was fed standard chow. The 3 remaining groups (n = 24 mice/group) were fed a SAFA-rich diet for 8 weeks and were then allocated for 16 weeks to either a MUFA-rich diet, an equal in MUFAs-SAFAs-rich diet, or continued the previous SAFA-rich diet. After 8 weeks, mice consuming SAFA-rich diet had increased weight, total cholesterol (TC), and high-density lipoprotein cholesterol (HDL-C) levels ( P < .05 vs baseline). At week 24, MUFA-rich and MUFA-SAFA rich diets decreased TC and low-density lipoprotein cholesterol (LDL-C) levels ( P < .05) compared with week 8. In conclusion, switching to MUFA-rich diets or substituting half of the SAFAs with MUFAs can reverse diet-induced-hypercholesterolemia.

Are Underlying Assumptions of Current Animal Models of Human Stroke Correct: from STAIRs to High Hurdles?

Animal models of acute ischemic stroke have been criticized for failing to translate to human stroke. Nevertheless, animal models are necessary to improve our understanding of stroke pathophysiology and to guide the development of new stroke therapies. The rabbit embolic clot model is one animal model that has led to an effective therapy in human acute ischemic stroke, namely tissue plasminogen activator (tPA). We propose that potential compounds that demonstrate efficacy in non-rabbit animal models of acute ischemic stroke should also be tested in the rabbit embolic blood clot model and, where appropriate, compared to tPA prior to investigation in humans. Furthermore, the use of anesthesia needs to be considered as a major confounder in animal models of acute ischemic stroke, and death should be included as an outcome measure in animal stroke studies. These steps, along with the current STAIRs recommendations, may improve the successful translation of experimental therapies to clinical stroke treatments.

Gene therapy in a humanized mouse model of familial hypercholesterolemia leads to marked regression of atherosclerosis

Background

Familial hypercholesterolemia (FH) is an autosomal codominant disorder caused by mutations in the low-density lipoprotein receptor (LDLR) gene. Homozygous FH patients (hoFH) have severe hypercholesterolemia leading to life threatening atherosclerosis in childhood and adolescence. Mice with germ line interruptions in the Ldlr and Apobec1 genes (Ldlr^−/−Apobec1^−/−) simulate metabolic and clinical aspects of hoFH, including atherogenesis on a chow diet.

Methods/Principal Findings

In this study, vectors based on adeno-associated virus 8 (AAV8) were used to deliver the gene for mouse Ldlr (mLDLR) to the livers of Ldlr^−/−Apobec1^−/− mice. A single intravenous injection of AAV8.mLDLR was found to significantly reduce plasma cholesterol and non-HDL cholesterol levels in chow-fed animals at doses as low as 3×10⁹ genome copies/mouse. Whereas Ldlr^−/−Apobec1^−/− mice fed a western-type diet and injected with a control AAV8.null vector experienced a further 65% progression in atherosclerosis over 2 months compared with baseline mice, Ldlr^−/−Apobec1^−/− mice treated with AAV8.mLDLR realized an 87% regression of atherosclerotic lesions after 3 months compared to baseline mice. Immunohistochemical analyses revealed a substantial remodeling of atherosclerotic lesions.

Conclusions/Significance

Collectively, the results presented herein suggest that AAV8-based gene therapy for FH may be feasible and support further development of this approach. The pre-clinical data from these studies will enable for the effective translation of gene therapy into the clinic for treatment of FH.

Trans-fatty acids in the diet stimulate atherosclerosis

Epidemiological evidence has associated dietary trans-fatty acids (TFAs) with coronary heart disease. It is assumed that TFAs stimulate atherosclerosis, but this has not been proven. The purpose of this study was to determine the effects of consuming 2 concentrations of TFAs obtained from commercially hydrogenated vegetable shortening on atherosclerotic development in the presence or absence of elevated dietary cholesterol. Low-density lipoprotein receptor-deficient mice were fed 1 of 7 experimental diets for 14 weeks: low regular fat (LR), low trans-fat (LT), regular high fat, high trans-fat (HT), or a diet containing 2% cholesterol with low regular fat (C + LR), low trans-fat (C + LT), or high trans-fat (C + HT). The extent of lesion development was quantified by en face examination of the dissected aortae. Dietary cholesterol supplementation significantly elevated serum cholesterol levels. Surprisingly, this rise was partially attenuated by the addition of TFAs (C + LT and C + HT) in the diet. Serum triglyceride levels were elevated with the higher-fat diets and with the combination of trans-fat and cholesterol. Animals consuming TFAs in the absence of dietary cholesterol developed a significantly greater extent of aortic atherosclerotic lesions as compared with control animals (LT > LR and HT > regular high fat). Atherosclerotic lesions were more extensive after cholesterol feeding, but the addition of TFAs to this atherogenic diet did not advance atherosclerotic development further. In summary, TFAs are atherogenic on their own; but they do not stimulate further effects beyond the strongly atherogenic effects of dietary cholesterol.

Identification of genes downregulated during differentiation of porcine mesenteric adipocytes

Adipose tissue development is a process that comprises not only hypertrophy, but also hyperplasia, of adipocytes. Although the proliferation of undifferentiated preadipocytes plays an important part in hyperplasia, this process is less well understood than the post-proliferation differentiation process. Despite the potential importance of porcine visceral adipose tissue to both meat production and biomedical research, there has been little study of this tissue and, in particular, its development and differentiation. To detect the genes involved in the maintenance of porcine visceral preadipocytes in an undifferentiated state or in the inhibition of adipocyte differentiation, we performed suppression subtractive hybridization using mesenteric preadipocytes in which fragments of the genes that are downregulated at 2 d of differentiation were enriched. We selected 672 clones and subjected them to differential screening and semiquantitative reverse transcription (RT)-PCR. As a result, we identified 34 downregulated genes. Among these, the detailed expression patterns of 6 genes were examined using real-time RT-PCR in both preadipocytes during in vitro differentiation and cell fractions directly isolated from pig mesenteric adipose tissue. The expressions of connective tissue growth factor, AXL receptor tyrosine kinase, stromal membrane-associated protein 1-like, and retinoic acid-induced 14 were significantly downregulated during adipocyte differentiation in vitro (P < 0.05), and the expressions of Rho/Rac guanine nucleotide exchange factor 2 and secreted frizzled-related protein 4 also tended to be decreased, although not significantly. Furthermore, all 6 genes showed significantly greater expression in stromal vascular cells, which contain preadipocytes, than in mature adipocytes (P < 0.05), raising the possibility that these genes are involved in adipocyte differentiation in vivo as well as in vitro.

Dietary cholesterol worsens adipose tissue macrophage accumulation and atherosclerosis in obese LDL receptor-deficient mice

OBJECTIVE

Chronic systemic inflammation accompanies obesity and predicts development of cardiovascular disease. Dietary cholesterol has been shown to increase inflammation and atherosclerosis in LDL receptor-deficient (LDLR(-/-)) mice. This study was undertaken to determine whether dietary cholesterol and obesity have additive effects on inflammation and atherosclerosis.

METHODS AND RESULTS

LDLR(-/-) mice were fed chow, high-fat, high-carbohydrate (diabetogenic) diets without (DD) or with added cholesterol (DDC) for 24 weeks. Effects on adipose tissue, inflammatory markers, and atherosclerosis were studied. Despite similar weight gain between DD and DDC groups, addition of dietary cholesterol increased insulin resistance relative to DD. Adipocyte hypertrophy, macrophage accumulation, and local inflammation were observed in intraabdominal adipose tissue in DD and DDC, but were significantly higher in the DDC group. Circulating levels of the inflammatory protein serum amyloid A (SAA) were 4.4-fold higher in DD animals and 15-fold higher in DDC animals than controls, suggesting chronic systemic inflammation. Hepatic SAA mRNA levels were similarly elevated. Atherosclerosis was increased in the DD-fed animals and further increased in the DDC group.

CONCLUSIONS

Obesity-induced macrophage accumulation in adipose tissue is exacerbated by dietary cholesterol. These local inflammatory changes in adipose tissue are associated with insulin resistance, systemic inflammation, and increased atherosclerosis in this mouse model.

Effect of blueberry feeding on plasma lipids in pigs

Two feeding trials were conducted with pigs to determine the effects of blueberry supplementation on plasma lipid levels and other indices of cardiovascular benefit. In the first trial, where basal diets contained a high level of plant-based components (70 % soya, oats and barley), supplementation with 1, 2 and 4 % blueberries resulted in a decrease in total, LDL- and HDL-cholesterol. The greatest reduction was observed in the 2 % blueberry-fed pigs, where total, LDL- and HDL-cholesterol were reduced 11.7, 15.1 and 8.3 %, respectively. In the second trial where basal diets contained only 20 % (w/w) of soya, oats and barley, the lipid-modulating effect of blueberries was attenuated, so that supplementation with 1.5 % blueberries reduced total cholesterol by 8 %, which occurred only in pigs whose diets had been supplemented with cholesterol (0.08 %), NaCl (0.11 %) and fructose (9 %). In the first feeding trial, blueberry supplementation had no effect on blood platelet activity. Blueberry supplementation also had no effect on the susceptibility of leucocyte DNA to oxidation in the first trial and no effect on the susceptibility of LDL to oxidation in the second trial. Results of these two feeding trials are discussed in relation to the effects of basal diet composition on lipid-modulating effects of blueberries.