A diet-induced hypercholesterolemic murine model to study atherogenesis without obesity and metabolic syndrome

Investigating the Role of Cannabinoid Type 1 Receptors in Vascular Function and Remodeling in a Hypercholesterolemic Mouse Model with Low-Density Lipoprotein-Cannabinoid Type 1 Receptor Double Knockout Animals

Hypercholesterolemia forms the background of several cardiovascular pathologies. LDL receptor-knockout (LDLR-KO) mice kept on a high-fat diet (HFD) develop high cholesterol levels and atherosclerosis (AS). Cannabinoid type 1 receptors (CB1Rs) induce vasodilation, although their role in cardiovascular pathologies is still controversial. We aimed to reveal the effects of CB1Rs on vascular function and remodeling in hypercholesterolemic AS-prone LDLR-KO mice. Experiments were performed on a newly established LDLR and CB1R double-knockout (KO) mouse model, in which KO and wild-type (WT) mice were kept on an HFD or a control diet (CD) for 5 months. The vascular functions of abdominal aorta rings were tested with wire myography. The vasorelaxation effects of acetylcholine (Ach, 1 nM-1 µM) were obtained after phenylephrine precontraction, which was repeated with inhibitors of nitric oxide synthase (NOS) and cyclooxygenase (COX), Nω-nitro-L-arginine (LNA), and indomethacin (INDO), respectively. Blood pressure was measured with the tail-cuff method. Immunostaining of endothelial NOS (eNOS) was carried out. An HFD significantly elevated the cholesterol levels in the LDLR-KO mice more than in the corresponding WT mice (mean values: 1039 ± 162 mg/dL vs. 91 ± 18 mg/dL), and they were not influenced by the presence of the CB1R gene. However, with the defect of the CB1R gene, damage to the Ach relaxation ability was moderated. The blood pressure was higher in the LDLR-KO mice compared to their WT counterparts (systolic/diastolic values: 110/84 ± 5.8/6.8 vs. 102/80 ± 3.3/2.5 mmHg), which was significantly elevated with an HFD (118/96 ± 1.9/2 vs. 100/77 ± 3.4/3.1 mmHg, p < 0.05) but attenuated in the CB1R-KO HFD mice. The expression of eNOS was depressed in the HFD WT mice compared to those on the CD, but it was augmented if CB1R was knocked out. This newly established double-knockout mouse model provides a tool for studying the involvement of CB1Rs in the development of hypercholesterolemia and atherosclerosis. Our results indicate that knocking out the CB1R gene significantly attenuates vascular damage in hypercholesterolemic mice.

Considerations for choosing an optimal animal model of cardiovascular disease

The decision to use the optimal animal model to mimic the various types of cardiovascular disease is a critical one for a basic scientist. Clinical cardiovascular disease can be complex and presents itself as atherosclerosis, hypertension, ischemia/reperfusion injury, myocardial infarcts, and cardiomyopathies, amongst others. This may be further complicated by the simultaneous presence of two or more cardiovascular lesions (for example, atherosclerosis and hypertension) and co-morbidities (i.e., diabetes, infectious disease, obesity, etc). This variety and merging of disease states creates an unusually difficult situation for the researcher who needs to identify the optimal animal model that is available to best represent all of the characteristics of the clinical cardiovascular disease. The present manuscript reviews the characteristics of the various animal models of cardiovascular disease available today, their advantages and disadvantages, with the goal to allow the reader access to the most recent data available for optimal choices prior to the initiation of the study. The animal species that can be chosen, the methods of generating these models of cardiovascular disease, as well as the specific cardiovascular lesions involved in each of these models are reviewed. A particular focus on the JCR:LA-cp rat as a model of cardiovascular disease is discussed.

Microbial oil, alone or paired with β-glucans, can control hypercholesterolemia in a zebrafish model

Dyslipidemia is often associated with unhealthy dietary habits, and many mammalian studies have explored the mode of action of certain bioactive compounds such as β-glucans and n-3 PUFAs to understand their potential to normalize the lipid metabolism. There are only a few investigations that adopted omic approaches to unveil their combined effect on hypercholesterolemia. Zebrafish (Danio rerio) was used as a model organism to reveal the efficacy of Schizochytrium oil and β-glucans (from Euglena gracilis and Phaeodactylum tricornutum) against cholesterol-rich diet induced dyslipidemia. One of the folowing four diets was fed to a particular group of fish: a control high-cholesterol diet, a Schizochytrium oil diet or one of the two diets containing the oil and β-glucan. The plasma HDL, expression of hepatic genes linked to, among others, ferric ion binding and plasma phosphatidylcholines were higher and plasma cholesterol esters and triacylglycerols were lower in the microbial oil-fed fish compared to the fish fed high cholesterol diet. While the fish fed a mix of microbial oil and Euglena β-glucan had lower plasma triacylglycerols and expression of hepatic genes linked to PPAR signaling pathway and enriched biosynthesis of plasma unsaturated fatty acids, the fish fed microbial oil-Phaeodactylum β-glucan combination had lower abundance of triacylglycerols rich in saturated and mono-unsaturated fatty acids and cholesterol esters in the plasma.

Scavenging dicarbonyls with 5'-O-pentyl-pyridoxamine increases HDL net cholesterol efflux capacity and attenuates atherosclerosis and insulin resistance

OBJECTIVE

Oxidative stress contributes to the development of insulin resistance (IR) and atherosclerosis. Peroxidation of lipids produces reactive dicarbonyls such as Isolevuglandins (IsoLG) and malondialdehyde (MDA) that covalently bind plasma/cellular proteins, phospholipids, and DNA leading to altered function and toxicity. We examined whether scavenging reactive dicarbonyls with 5'-O-pentyl-pyridoxamine (PPM) protects against the development of IR and atherosclerosis in Ldlr^-/- mice.

METHODS

Male or female Ldlr^-/- mice were fed a western diet (WD) for 16 weeks and treated with PPM versus vehicle alone. Plaque extent, dicarbonyl-lysyl adducts, efferocytosis, apoptosis, macrophage inflammation, and necrotic area were measured. Plasma MDA-LDL adducts and the in vivo and in vitro effects of PPM on the ability of HDL to reduce macrophage cholesterol were measured. Blood Ly6C^hi monocytes and ex vivo 5-ethynyl-2'-deoxyuridine (EdU) incorporation into bone marrow CD11b+ monocytes and CD34+ hematopoietic stem and progenitor cells (HSPC) were also examined. IR was examined by measuring fasting glucose/insulin levels and tolerance to insulin/glucose challenge.

RESULTS

PPM reduced the proximal aortic atherosclerosis by 48% and by 46% in female and male Ldlr^-/- mice, respectively. PPM also decreased IR and hepatic fat and inflammation in male Ldlr^-/- mice. Importantly, PPM decreased plasma MDA-LDL adducts and prevented the accumulation of plaque MDA- and IsoLG-lysyl adducts in Ldlr^-/- mice. In addition, PPM increased the net cholesterol efflux capacity of HDL from Ldlr^-/- mice and prevented both the in vitro impairment of HDL net cholesterol efflux capacity and apoAI crosslinking by MPO generated hypochlorous acid. Moreover, PPM decreased features of plaque instability including decreased proinflammatory M1-like macrophages, IL-1β expression, myeloperoxidase, apoptosis, and necrotic core. In contrast, PPM increased M2-like macrophages, Tregs, fibrous cap thickness, and efferocytosis. Furthermore, PPM reduced inflammatory monocytosis as evidenced by decreased blood Ly6C^hi monocytes and proliferation of bone marrow monocytes and HSPC from Ldlr^-/- mice.

CONCLUSIONS

PPM has pleotropic atheroprotective effects in a murine model of familial hypercholesterolemia, supporting the therapeutic potential of reactive dicarbonyl scavenging in the treatment of IR and atherosclerotic cardiovascular disease.

Suppression of Ca2+ signaling enhances melanoma progression

The role of store-operated Ca2+ entry (SOCE) in melanoma metastasis is highly controversial. To address this, we here examined UV-dependent metastasis, revealing a critical role for SOCE suppression in melanoma progression. UV-induced cholesterol biosynthesis was critical for UV-induced SOCE suppression and subsequent metastasis, although SOCE suppression alone was both necessary and sufficient for metastasis to occur. Further, SOCE suppression was responsible for UV-dependent differences in gene expression associated with both increased invasion and reduced glucose metabolism. Functional analyses further established that increased glucose uptake leads to a metabolic shift towards biosynthetic pathways critical for melanoma metastasis. Finally, examination of fresh surgically isolated human melanoma explants revealed cholesterol biosynthesis-dependent reduced SOCE. Invasiveness could be reversed with either cholesterol biosynthesis inhibitors or pharmacological SOCE potentiation. Collectively, we provide evidence that, contrary to current thinking, Ca2+ signals can block invasive behavior, and suppression of these signals promotes invasion and metastasis.

Aortic Fibrosis in Insulin-Sensitive Mice with Endothelial Cell-Specific Deletion of Ceacam1 Gene

(1) Background: Mice with global Ceacam1 deletion developed plaque-like aortic lesions even on C57BL/6J background in the presence of increased endothelial cell permeability and insulin resistance. Loss of endothelial Ceacam1 gene caused endothelial dysfunction and reduced vascular integrity without affecting systemic insulin sensitivity. Because endothelial cell injury precedes atherosclerosis, we herein investigated whether the loss of endothelial Ceacam1 initiates atheroma formation in the absence of insulin resistance. (2) Methods: Endothelial cell-specific Ceacam1 null mice on C57BL/6J.Ldlr-/- background (Ldlr-/-VECadCre+Cc1fl/fl) were fed an atherogenic diet for 3-5 months before metabolic, histopathological, and en-face analysis of aortae were compared to their control littermates. Sirius Red stain was also performed on liver sections to analyze hepatic fibrosis. (3) Results: These mice displayed insulin sensitivity without significant fat deposition on aortic walls despite hypercholesterolemia. They also displayed increased inflammation and fibrosis. Deleting Ceacam1 in endothelial cells caused hyperactivation of VEGFR2/Shc/NF-κB pathway with resultant transcriptional induction of NF-κB targets. These include IL-6 that activates STAT3 inflammatory pathways, in addition to endothelin-1 and PDGF-B profibrogenic effectors. It also induced the association between SHP2 phosphatase and VEGFR2, downregulating the Akt/eNOS pathway and reducing nitric oxide production, a characteristic feature of endothelial dysfunction. Similarly, hepatic inflammation and fibrosis developed in Ldlr-/-VECadCre+Cc1fl/fl mice without an increase in hepatic steatosis. (4) Conclusions: Deleting endothelial cell Ceacam1 caused hepatic and aortic inflammation and fibrosis with increased endothelial dysfunction and oxidative stress in the presence of hypercholesterolemia. However, this did not progress into frank atheroma formation. Because these mice remained insulin sensitive, the study provides an in vivo demonstration that insulin resistance plays a critical role in the pathogenesis of frank atherosclerosis.

Non-alcoholic Fatty Liver Disease and Steatohepatitis: Risk Factors and Pathophysiology

Non-alcoholic fatty liver disease (NAFLD) and its progressive subtype non-alcoholic steatohepatitis (NASH) are the most prevalent liver diseases, often leading to hepatocellular carcinoma (HCC). This review aims to describe the present knowledge of the risk factors responsible for the development of NAFLD and NASH. I performed a literature review identifying studies focusing on the complex pathogenic pathway and risk factors of NAFLD and steatohepatitis. The relationship between NAFLD and metabolic syndrome is well established and widely recognized. Obesity, dyslipidemia, type 2 diabetes, hypertension, and insulin resistance are the most common risk factors associated with NAFLD. Among the components of metabolic syndrome, current evidence strongly suggests obesity and type 2 diabetes as risk factors of NASH and HCC. However, other elements, namely gender divergences, ethnicity, genetic factors, participation of innate immune system, oxidative stress, apoptotic pathways, and adipocytokines, take a leading role in the onset and promotion of NAFLD. Pathophysiological mechanisms that are responsible for NAFLD development and subsequent progression to NASH are insulin resistance and hyperinsulinemia, oxidative stress, hepatic stellate cell (HSC) activation, cytokine/adipokine signaling pathways, and genetic and environmental factors. Major pathophysiological findings of NAFLD are dysfunction of adipose tissue through the enhanced flow of free fatty acids (FFAs) and release of adipokines, and altered gut microbiome that generate proinflammatory signals and cause NASH progression. Understanding the pathophysiology and risk factors of NAFLD and NASH; this review could provide insight into the development of therapeutic strategies and useful diagnostic tools.

Pig and Mouse Models of Hyperlipidemia and Atherosclerosis

Atherosclerosis is a chronic inflammatory disorder that is the underlying cause of most cardiovascular disease. Resident cells of the artery wall and cells of the immune system participate in atherogenesis. This process is influenced by plasma lipoproteins, genetics, and the hemodynamics of the blood flow in the artery. A variety of animal models have been used to study the pathophysiology and mechanisms that contribute to atherosclerotic lesion formation. No model is ideal as each has its own advantages and limitations with respect to manipulation of the atherogenic process and modeling human atherosclerosis and lipoprotein profile. In this chapter we will discuss pig and mouse models of experimental atherosclerosis. The similarity of pig lipoprotein metabolism and the pathophysiology of the lesions in these animals with that of humans is a major advantage. While a few genetically engineered pig models have been generated, the ease of genetic manipulation in mice and the relatively short time frame for the development of atherosclerosis has made them the most extensively used model. Newer approaches to induce hypercholesterolemia in mice have been developed that do not require germline modifications. These approaches will facilitate studies on atherogenic mechanisms.

Computational Screening Strategy for Drug Repurposing Identified Niclosamide as Inhibitor of Vascular Calcification

Vascular calcification is a cardiovascular disorder with no therapeutic options. We recently reported that o-octanoyltransferase (CROT) suppression can inhibit vascular calcification in vivo and in vitro through amelioration of mitochondrial function and fatty acid metabolism. Inhibiting calcification with a small molecule compound targeting CROT-associated mechanisms will be a promising non-invasive treatment of vascular calcification. Here we used a computational approach to search for existing drugs that can inhibit vascular calcification through the CROT pathway. For screening of the compounds that reduce CROT expression, we utilized the Connectivity Map encompassing the L1000 computational platform that contains transcription profiles of various cell lines and perturbagens including small molecules. Small molecules (n = 13) were identified and tested in human primary smooth muscle cells cultured in osteogenic media to induce calcification. Niclosamide, an FDA-improved anthelmintic drug, markedly inhibited calcification along with reduced alkaline phosphatase activity and CROT mRNA expression. To validate this compound in vivo, LDL receptor (Ldlr)-deficient mice fed a high fat diet were given oral doses of niclosamide (0 or 750 ppm admixed with diet) for 10 weeks. Niclosamide treatment decreased aortic and carotid artery calcification as determined by optical near infrared molecular imaging (OsteoSense680) and histological analysis. In addition, niclosamide improved features of fatty liver, including decreased cholesterol levels along with decreased Crot expression, while plasma total cholesterol levels did not change. Proteomic analysis of aortic samples demonstrated that niclosamide affected wingless/integrated (Wnt) signaling pathway and decreased runt-related transcription factor 2 (Runx2) expression, an essential factor for calcification. Our target discovery strategy using a genetic perturbation database with existing drugs identified niclosamide, that in turn inhibited calcification in vivo and in vitro, indicating its potential for the treatment of vascular calcification.

Hypercholesterolemia as a dominant factor of central obesity among adult patients at Bojong Gede Public Health Center, Bogor Regency, Indonesia

The prevalence of central obesity has been increasing rapidly in recent decades. Central obesity, measured by waist circumference, is the most dangerous type of obesity since it is closely related to chronic diseases, metabolic complications, and high COVID-19 infection rates. The objective of this study was to identify the dominant factor of central obesity among the adult population. The study used secondary data from a 2017 cross-sectional study conducted at Bojong Gede Public Health Center, Bogor Regency, Indonesia. A total of 85 men and women aged 25–64 years old were selected through purposive sampling and included in the analysis. The association between risk factors and central obesity were measured through chi-square bivariate analysis and multiple logistic regression multivariate analysis using IBM SPSS application version 22. The prevalence of central obesity was 70.6%. The results showed that sex (women), total blood cholesterol level (hypercholesterolemia), energy, protein, fat, and carbohydrate intake (>110%personal nutritional needs) were significantly associated with central obesity (p-value <  0.05). Hypercholesterolemia was the most dominant risk factor for central obesity (p-value = 0.032; OR = 4.21; 95%CI = 1.131–15.667) adjusted for confounders.

Preclinical techniques to investigate exercise training in vascular pathophysiology

Atherosclerosis is a dynamic process starting with endothelial dysfunction and inflammation and eventually leading to life-threatening arterial plaques. Exercise generally improves endothelial function in a dose-dependent manner by altering hemodynamics, specifically by increased arterial pressure, pulsatility, and shear stress. However, athletes who regularly participate in high-intensity training can develop arterial plaques, suggesting alternative mechanisms through which excessive exercise promotes vascular disease. Understanding the mechanisms that drive atherosclerosis in sedentary versus exercise states may lead to novel rehabilitative methods aimed at improving exercise compliance and physical activity. Preclinical tools, including in vitro cell assays, in vivo animal models, and in silico computational methods, broaden our capabilities to study the mechanisms through which exercise impacts atherogenesis, from molecular maladaptation to vascular remodeling. Here, we describe how preclinical research tools have and can be used to study exercise effects on atherosclerosis. We then propose how advanced bioengineering techniques can be used to address gaps in our current understanding of vascular pathophysiology, including integrating in vitro, in vivo, and in silico studies across multiple tissue systems and size scales. Improving our understanding of the antiatherogenic exercise effects will enable engaging, targeted, and individualized exercise recommendations to promote cardiovascular health rather than treating cardiovascular disease that results from a sedentary lifestyle.

Lactobacillus reuteri attenuates cardiac injury without lowering cholesterol in low-density lipoprotein receptor-deficient mice fed standard chow

Disruption of the normal gut microbiome (dysbiosis) is implicated in the progression and severity of myriad disorders, including hypercholesterolemia and cardiovascular disease. Probiotics attenuate and reverse gut dysbiosis to improve cardiovascular risk factors like hypertension and hypercholesterolemia. Lactobacillus reuteri is a well-studied lactic acid-producing probiotic with known cholesterol-lowering properties and anti-inflammatory effects. In the present study, we hypothesized that L. reuteri delivered to hypercholesterolemic low-density lipoprotein receptor knockout (LDLr KO) mice will reduce cholesterol levels and minimize cardiac injury from an ischemic insult. L. reuteri [1 × 10⁹ or 50 × 10⁶ colony-forming units (CFU)/day] was administered by oral gavage to wild-type mice and LDLr KO for up to 6 wk followed by an ischemia-reperfusion (I/R) protocol. After 4 wk of gavage, total serum cholesterol in wild-type mice receiving saline was 113.5 ± 5.6 mg/dL compared with 113.3 ± 6.8 and 101.9 ± 7.5 mg/dL in mice receiving 1 × 10⁹ or 50 × 10⁶ CFU/day, respectively. Over the same time frame, administration of L. reuteri at 1 × 10⁹ or 50 × 10⁶ CFU/day did not lower total serum cholesterol (283.0 ± 11.1, 263.3 ± 5.0, and 253.1 ± 7.0 mg/dL; saline, 1 × 10⁹ or 50 × 10⁶ CFU/day, respectively) in LDLr KO mice. Despite no impact on total serum cholesterol, L. reuteri administration significantly attenuated cardiac injury following I/R, as evidenced by smaller infarct sizes compared with controls in both wild-type and LDLr KO groups. In conclusion, daily L. reuteri significantly protected against cardiac injury without lowering cholesterol levels, suggesting anti-inflammatory properties of L. reuteri uncoupled from improvements in serum cholesterol.NEW & NOTEWORTHY We demonstrated that daily delivery of Lactobacillus reuteri to wild-type and hypercholesterolemic lipoprotein receptor knockout mice attenuated cardiac injury following ischemia-reperfusion without lowering total serum cholesterol in the short term. In addition, we validated protection against cardiac injury using histology and immunohistochemistry techniques. L. reuteri offers promise as a probiotic to mitigate ischemic cardiac injury.

Myosin light chain kinase inhibitor ML7 improves vascular endothelial dysfunction and permeability via the mitogen-activated protein kinase pathway in a rabbit model of atherosclerosis

Endothelial dysfunction (ED) and hyperpermeability are considered as the initiating steps in early atherosclerosis. Phosphorylation of myosin light chain (MLC) is key to cause vascular hyperpermeability via endothelial cell contraction. However, it is unclear whether MLC phosphorylation can also regulate the balance between contraction and relaxation of endothelial cells, thereby affecting endothelium-dependent diastolic function and leading to ED. The present study investigated relationships between ED and MLC phosphorylation and underlying mechanisms. Twenty-four male New Zealand white rabbits were randomly divided into three groups: control, AS, and ML7 (MLCK inhibitor) groups, and fed with normal diet, high-fat diet (HFD), and HFD plus oral ML7 (1 mg/kg daily) respectively. HFD-fed rabbits showed typical atheromatous lesions and endothelial hyperpermeability, and these lesions could be partly reversed following ML7 therapy. Western blotting revealed significant increased expression of myosin light chain kinase (MLCK) and phosphorylation of MLC, JNK, and ERK in the arterial wall of rabbits in the AS group compared with those of the control group (p < 0.05), whereas the ML7 group showed markedly decreased levels of these proteins compared with the AS group (p <  0.05). The endothelium-dependent relaxation rate was significantly reduced both in vitro and in vivo in AS group, and was improved using ML7 therapy. Taken together, these results indicate that MLCK expression and subsequent MLC phosphorylation increase vascular endothelial permeability and endothelium-dependent diastolic dysfunction by promoting endothelial cell contraction, which may be initiated by the activation of the MAP/ERK (MEK) and MAP/JNK (MEK) pathways.

Synergistic anti-atherosclerotic role of combined treatment of omega-3 and co-enzyme Q10 in hypercholesterolemia-induced obese rats

Hypercholesterolemia is a metabolic disorder associated with atherosclerosis. This study aimed to investigate the effects of omega-3 and/or coenzyme Q10 (CoQ10) on hypercholesterolemia-induced atherosclerosis. Rats were divided into five groups; (1): served as the negative control, (2): served as hypercholesterolemic (HC) control, (3): HC-rats administrated omega-3 orally, (4): HC-rats administrated CoQ10 orally, and (5): HC-rats administered the combination treatment of both omega-3 and CoQ10. Lipid profile was assayed and cardiovascular risk indices were calculated. Serum levels of Adiponectin (APN) and creatine kinase (CK-MB) were determined using ELISA. Besides, oxidative stress markers, malondialdehyde (MDA), nitric oxide (NO) and glutathione (GSH) were assayed in the heart homogenate. Histopathological investigation of the aortae and heart tissues were investigated. The results revealed that atherogenic HC-rats demonstrated a significant elevation in lipid profiles, except for HDL-C, along with decreased levels of APN, but increased CK-MB activities. Hypercholesterolemia increased lipid peroxidation, reduced NO production, and decreased GSH content in the cardiac tissue. Treatment of atherogenic HC-rats with omega-3 and/or CoQ10 improved dyslipidemia and ameliorated most of the HC-induced biochemical and histopathological changes. The histological observations of aortae and cardiac tissues validated our biochemical results. We concluded that the combined treatment of nutraceuticals such as omega-3 and CoQ10 demonstrated the best outcome, demonstrating their anti-hyperlipidemic, cardioprotective, and atheroprotective potentials. Together, this study supports a beneficial role of dietary co-administration of omega-3 and CoQ10 in obese patients who are prone to develop cardiovascular disorders.

Cow's milk polar lipids reduce atherogenic lipoprotein cholesterol, modulate gut microbiota and attenuate atherosclerosis development in LDL-receptor knockout mice fed a Western-type diet

Milk sphingomyelin (SM), a polar lipid (PL) component of milk fat globule membranes, is protective against dyslipidemia. However, it is unclear whether ingestion of milk PLs protect against atherosclerosis. To determine this, male LDLr^-/- mice (age 6 weeks) were fed ad libitum either a high-fat, added-cholesterol diet (CTL; 45% kcal from fat, 0.2% cholesterol by weight; n=15) or the same diet supplemented with 1% milk PL (1% MPL; n=15) or 2% milk PL (2% MPL; n=15) added by weight from butter serum. After 14 weeks on diets, mice fed 2% MPL had significantly lower serum cholesterol (-51%) compared to CTL (P<.01), with dose-dependent effects in lowering VLDL- and LDL-cholesterol. Mice fed 2% MPL displayed lower inflammatory markers in the serum, liver, adipose and aorta. Notably, milk PLs reduced atherosclerosis development in both the thoracic aorta and the aortic root, with 2% MPL-fed mice having significantly lower neutral lipid plaque size by 59% (P<.01) and 71% (P<.02) compared to CTL, respectively. Additionally, the 2% MPL-fed mice had greater relative abundance of Bacteroidetes, Actinobacteria and Bifidobacterium, and lower Firmicutes in cecal feces compared to CTL. Milk PL feeding resulted in significantly different microbial communities as demonstrated by altered beta diversity indices. In summary, 2% MPL strongly reduced atherogenic lipoprotein cholesterol, modulated gut microbiota, lowered inflammation and attenuated atherosclerosis development. Thus, milk PL content may be important to consider when choosing dairy products as foods for cardiovascular disease prevention.

Dietary fermented products using koji mold and sweet potato-shochu distillery by-product promotes hepatic and serum cholesterol levels and modulates gut microbiota in mice fed a high-cholesterol diet

It has been reported that fermented products (FPs) prepared from sweet potato-shochu distillery by-product suppressed weight gain and decreased serum cholesterol levels in mice under normal dietary conditions. Furthermore, from the information gained from the above data regarding health benefits of the FPs, the aim of this study was evaluating the effects of dietary FPs on lipid accumulation and gut microbiota in mice with or without cholesterol-load in the diet. C57BL/6N mice were fed normal (CO) diet, CO with 10% FPs (CO + FPs) diet, cholesterol loaded (HC) diet, or HC with 10% FPs (HC + FPs) diet for 8 weeks. The mice were then euthanized, and blood samples, tissue samples, and feces were collected. The adipose tissue weight and liver triglyceride levels in the HC + FPs diet groups were significantly reduced compared to that in the HC diet groups. However, FPs significantly increased the serum non-high-density lipoprotein cholesterol (HDL-C) levels, the ratio of non-HDL-C to HDL-C and hepatic total cholesterol levels in mice fed cholesterol-loaded diet compared with that of the HC diet group. Since dietary FPs significantly decreased the protein expression levels of cholesterol 7 alpha-hydroxylase 1 in the HC + FPs diet groups, the cholesterol accumulation in FPs group may be explained by insufficient catabolism from cholesterol to bile acid. In addition, the dietary FPs tended to increase Clostridium cluster IV and XIVa, which are butyrate-producing bacteria. Related to the result, n-butyrate was significantly increased in the CO + FPs and the HC + FPs diet groups compared to their respective control groups. These findings suggested that dietary FPs modulated the lipid pool and gut microbiota.

Worsening of Oxidative Stress, DNA Damage, and Atherosclerotic Lesions in Aged LDLr-/- Mice after Consumption of Guarana Soft Drinks

BACKGROUND

Excessive consumption of soft drinks (SD) has become a health problem worldwide due to its association with related cardiovascular diseases. We investigated the possible impacts associated with the consumption of Brazilian guarana (normal and zero) SD in dyslipidemic mice, thus mitigating potential clinical confounders such as poor-quality diet, lifestyle, body composition, and/or comorbidities.

METHODS

Sixteen-month-old LDLr-/- mice were divided into the following groups: (1) control; (2) GSD: normal guarana SD; and (3) Z-GSD: zero guarana SD. All were fed ad libitum, and blood pressure was measured noninvasively. After 8 weeks, aorta, blood, liver, and stomach samples were collected for histological and biochemical analyses.

RESULTS

Guarana soft drinks increased atherosclerosis (~60%) and were associated with hypercholesterolemia, hypertension, oxidative stress, DNA fragmentation, and apoptosis (~2-fold) of blood cells, besides presenting an increase in liver and gastric damage even in normoglycemia. Interestingly, Z-GSD did not cause the aforementioned changes, except in hemodynamic and renal parameters.

CONCLUSIONS

Chronic administration of GSD is prooxidative, compromising the cardiovascular, gastric, and hepatic systems; the effects are due at least in part to free sugar consumption but not to guarana extract per se.

Regulation of lipid rafts, angiogenesis and inflammation by AIBP

PURPOSE OF REVIEW

Recent studies demonstrate an important role of the secreted apolipoprotein A-I binding protein (AIBP) in regulation of cholesterol efflux and lipid rafts. The article discusses these findings in the context of angiogenesis and inflammation.

RECENT FINDINGS

Lipid rafts are cholesterol-rich and sphingomyelin-rich membrane domains in which many receptor complexes assemble upon activation. AIBP mediates selective cholesterol efflux, in part via binding to toll-like receptor-4 (TLR4) in activated macrophages and microglia, and thus reverses lipid raft increases in activated cells. Recent articles report AIBP regulation of vascular endothelial growth factor receptor-2, Notch1 and TLR4 function. In zebrafish and mouse animal models, AIBP deficiency results in accelerated angiogenesis, increased inflammation and exacerbated atherosclerosis. Spinal delivery of recombinant AIBP reduces neuraxial inflammation and reverses persistent pain state in a mouse model of chemotherapy-induced polyneuropathy. Inhalation of recombinant AIBP reduces lipopolysaccharide-induced acute lung injury in mice. These findings are discussed in the perspective of AIBP's proposed other function, as an NAD(P)H hydrate epimerase, evolving into a regulator of cholesterol trafficking and lipid rafts.

SUMMARY

Novel findings of AIBP regulatory circuitry affecting lipid rafts and related cellular processes may provide new therapeutic avenues for angiogenic and inflammatory diseases.

CX3CL1-Fc treatment prevents atherosclerosis in Ldlr KO mice

OBJECTIVE

Atherosclerosis is a major cause of cardiovascular disease. Monocyte-endothelial cell interactions are partly mediated by expression of monocyte CX3CR1 and endothelial cell fractalkine (CX3CL1). Interrupting the interaction between this ligand-receptor pair should reduce monocyte binding to the endothelial wall and reduce atherosclerosis. We sought to reduce atherosclerosis by preventing monocyte-endothelial cell interactions through use of a long-acting CX3CR1 agonist.

METHODS

In this study, the chemokine domain of CX3CL1 was fused to the mouse Fc region to generate a long-acting soluble form of CX3CL1 suitable for chronic studies. CX3CL1-Fc or saline was injected twice a week (30 mg/kg) for 4 months into Ldlr knockout (KO) mice on an atherogenic western diet.

RESULTS

CX3CL1-Fc-treated Ldlr KO mice showed decreased en face aortic lesion surface area and reduced aortic root lesion size with decreased necrotic core area. Flow cytometry analyses of CX3CL1-Fc-treated aortic wall cell digests revealed a decrease in M1-like polarized macrophages and T cells. Moreover, CX3CL1-Fc administration reduced diet-induced atherosclerosis after switching from an atherogenic to a normal chow diet. In vitro monocyte adhesion studies revealed that CX3CL1-Fc treatment caused fewer monocytes to adhere to a human umbilical vein endothelial cell monolayer. Furthermore, a dorsal window chamber model demonstrated that CX3CL1-Fc treatment decreased in vivo leukocyte adhesion and rolling in live capillaries after short-term ischemia-reperfusion.

CONCLUSION

These results indicate that CX3CL1-Fc can inhibit monocyte/endothelial cell adhesion as well as reduce atherosclerosis.

Comparison between red wine and isolated trans-resveratrol on the prevention and regression of atherosclerosis in LDLr (-/-) mice

Moderate consumption of red wine has been widely associated with reduced cardiovascular risk, mainly due to its composition in phenolic compounds with antioxidant activity, such as resveratrol. The objective of this study was to compare the effect of red wine vs. trans-resveratrol consumption on the prevention and regression of atherosclerosis in LDLr ^(-/-) mice. This study consisted of two protocols: "Prevention" (PREV) and "Regression" (REGR). Both protocols included four groups: red wine (WINE), dealcoholized red wine (EXT), trans-resveratrol (RESV), and control (CONT). In PREV protocol, animals received a regular diet for 8 weeks and then switched to an atherogenic diet for the following 8 weeks, while the opposite was performed in REGR. Animals that received atherogenic diet after an initial period of standard diet (PREV) gained more body weight (39.25±2.30%) than the opposite (29.27±1.91%, P=.0013), suggesting an interaction between age and weight gain. Trans-resveratrol showed the highest hypocholesterolemic effect during PREV, reducing total cholesterol, LDL-C, VLDL-C and HDL-C. Supplementation with trans-resveratrol and dealcoholized red wine changed the fatty acids profile in the liver in both protocols, leading to an increase of MDA concentrations and SOD activity in the PREV protocol. In conclusion, supplementation with trans-resveratrol, red wine and the same wine without alcohol altered biomarkers of oxidative stress and lipidemia but had no effect on the prevention or regression of fatty streaks. These data suggest that cardiovascular protection associated with the "French Paradox" may be a result of synergistic effects between wine and the Mediterranean diet.

Understanding the Impact of Dietary Cholesterol on Chronic Metabolic Diseases through Studies in Rodent Models

The development of certain chronic metabolic diseases has been attributed to elevated levels of dietary cholesterol. However, decades of research in animal models and humans have demonstrated a high complexity with respect to the impact of dietary cholesterol on the progression of these diseases. Thus, recent investigations in non-alcoholic fatty liver disease (NAFLD) point to dietary cholesterol as a key factor for the activation of inflammatory pathways underlying the transition from NAFLD to non-alcoholic steatohepatitis (NASH) and to hepatic carcinoma. Dietary cholesterol was initially thought to be the key factor for cardiovascular disease development, but its impact on the disease depends partly on the capacity to modulate plasmatic circulating low-density lipoprotein (LDL) cholesterol levels. These studies evidence a complex relationship between these chronic metabolic diseases and dietary cholesterol, which, in certain conditions, might promote metabolic complications. In this review, we summarize rodent studies that evaluate the impact of dietary cholesterol on these two prevalent chronic diseases and their relevance to human pathology.

Obesity and Insulin Resistance Promote Atherosclerosis through an IFNγ-Regulated Macrophage Protein Network

Type 2 diabetes (T2D) is associated with increased risk for atherosclerosis; however, the mechanisms underlying this relationship are poorly understood. Macrophages, which are activated in T2D and causatively linked to atherogenesis, are an attractive mechanistic link. Here, we use proteomics to show that diet-induced obesity and insulin resistance (obesity/IR) modulate a pro-atherogenic "macrophage-sterol-responsive-network" (MSRN), which, in turn, predisposes macrophages to cholesterol accumulation. We identify IFNγ as the mediator of obesity/IR-induced MSRN dysregulation and increased macrophage cholesterol accumulation and show that obesity/IR primes T cells to increase IFNγ production. Accordingly, myeloid cell-specific deletion of the IFNγ receptor (Ifngr1-/-) restores MSRN proteins, attenuates macrophage cholesterol accumulation and atherogenesis, and uncouples the strong relationship between hyperinsulinemia and aortic root lesion size in hypercholesterolemic Ldlr-/- mice with obesity/IR, but does not affect these parameters in Ldlr-/- mice without obesity/IR. Collectively, our findings identify an IFNγ-macrophage pathway as a mechanistic link between obesity/IR and accelerated atherogenesis.

Activities of purine converting enzymes in heart, liver and kidney mice LDLR-/- and Apo E-/

Nucleotide metabolism plays a major role in a number of vital cellular processes such as energetics. This, in turn, is important in pathologies such as atherosclerosis. Three month old atherosclerotic mice with knock outs for LDLR and apolipoprotein E (ApoE) were used for the experiments. Activities of AMP-deaminase (AMPD), ecto5'-nucleotidase (e5NT), adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP) were measured in heart, liver and kidney cortex and medulla by analysing conversion of substrates into products using HPLC. The activity of ecto5'-nucleotidase differ in hearts of LDLR^-/- and ApoE^-/- mice with no differences in ADA and AMPD activity. We noticed highest activity of e5NT in kidney medulla of the models. This model of atherosclerosis characterize with an inhibition of enzyme responsible for production of protective adenosine in heart but not in other organs and different metabolism of nucleotides in kidney medulla.

AIBP protects against metabolic abnormalities and atherosclerosis

Apolipoprotein A-I binding protein (AIBP) has been shown to augment cholesterol efflux from endothelial cells and macrophages. In zebrafish and mice, AIBP-mediated regulation of cholesterol levels in the plasma membrane of endothelial cells controls angiogenesis. The goal of this work was to evaluate metabolic changes and atherosclerosis in AIBP loss-of-function and gain-of-function animal studies. Here, we show that Apoa1bp^-/-Ldlr^-/- mice fed a high-cholesterol, high-fat diet had exacerbated weight gain, liver steatosis, glucose intolerance, hypercholesterolemia, hypertriglyceridemia, and larger atherosclerotic lesions compared with Ldlr^-/- mice. Feeding Apoa1bp^-/-Ldlr^-/- mice a high-cholesterol, normal-fat diet did not result in significant differences in lipid levels or size of atherosclerotic lesions from Ldlr^-/- mice. Conversely, adeno-associated virus-mediated overexpression of AIBP reduced hyperlipidemia and atherosclerosis in high-cholesterol, high-fat diet-fed Ldlr^-/- mice. Injections of recombinant AIBP reduced aortic inflammation in Ldlr^-/- mice fed a short high-cholesterol, high-fat diet. Conditional overexpression of AIBP in zebrafish also reduced diet-induced vascular lipid accumulation. In experiments with isolated macrophages, AIBP facilitated cholesterol efflux to HDL, reduced lipid rafts content, and inhibited inflammatory responses to lipopolysaccharide.jlr Our data demonstrate that AIBP confers protection against diet-induced metabolic abnormalities and atherosclerosis.

Dietary Fatty Acids Alter Lipid Profiles and Induce Myocardial Dysfunction without Causing Metabolic Disorders in Mice

Oversupply of bulk saturated fatty acids (SFA) induces metabolic disorders and myocardial dysfunction. We investigated whether, without causing metabolic disorders, the uptake of individual dietary SFA species alters lipid profiles and induces myocardial dysfunction. C57BL/6 mice were fed various customized long-chain SFA diets (40% caloric intake from SFA), including a beef tallow (HBD), cocoa butter (HCD), milk fat (HMD) and palm oil diet (HPD), for 6 months. An isocaloric fat diet, containing medium-chain triglycerides, served as a control (CHD). Long-term intake of dietary long-chain SFA differentially affected the fatty acid composition in cardiac phospholipids. All long-chain SFA diets increased the levels of arachidonic acid and total SFA in cardiac phospholipids. The preferential incorporation of individual SFA into the cardiac phospholipid fraction was dependent on the dietary SFA species. Cardiac ceramide content was elevated in all mice fed long-chain SFA diets, while cardiac hypertrophy was only presented in mice fed HMD or HPD. We have demonstrated that the intake of long-chain SFA species differentially alters cardiac lipid profiles and induces cardiac dysfunction, without causing remarkable metabolic disorders.

Recommendation on Design, Execution, and Reporting of Animal Atherosclerosis Studies: A Scientific Statement From the American Heart Association

Animal studies are a foundation for defining mechanisms of atherosclerosis and potential targets of drugs to prevent lesion development or reverse the disease. In the current literature, it is common to see contradictions of outcomes in animal studies from different research groups, leading to the paucity of extrapolations of experimental findings into understanding the human disease. The purpose of this statement is to provide guidelines for development and execution of experimental design and interpretation in animal studies. Recommendations include the following: (1) animal model selection, with commentary on the fidelity of mimicking facets of the human disease; (2) experimental design and its impact on the interpretation of data; and (3) standard methods to enhance accuracy of measurements and characterization of atherosclerotic lesions.

Recommendation on Design, Execution, and Reporting of Animal Atherosclerosis Studies: A Scientific Statement From the American Heart Association

Animal studies are a foundation for defining mechanisms of atherosclerosis and potential targets of drugs to prevent lesion development or reverse the disease. In the current literature, it is common to see contradictions of outcomes in animal studies from different research groups, leading to the paucity of extrapolations of experimental findings into understanding the human disease. The purpose of this statement is to provide guidelines for development and execution of experimental design and interpretation in animal studies. Recommendations include the following: (1) animal model selection, with commentary on the fidelity of mimicking facets of the human disease; (2) experimental design and its impact on the interpretation of data; and (3) standard methods to enhance accuracy of measurements and characterization of atherosclerotic lesions.

Episomal Nonviral Gene Therapy Vectors Slow Progression of Atherosclerosis in a Model of Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is a life-threatening genetic disorder characterized by elevated levels of plasma low-density lipoprotein cholesterol (LDL-cholesterol). Current attempts at gene therapy for FH have been limited by the use of strong heterologous promoters which lack genomic DNA elements essential for regulated expression. Here, we have combined a mini-gene vector expressing the human LDLR cDNA from a 10 kb native human LDLR locus genomic DNA promoter element, with an efficient miRNA targeting 3-hydroxy-3-methylgutaryl-coenzyme A reductase (Hmgcr), to further enhance LDLR expression. We show that the combined vector suppresses endogenous Hmgcr transcripts in vivo, leading to an increase in LDLR transgene expression. In a diet-induced Ldlr^-/- mouse model of FH, we show that administration of the combined vector reduces atherogenic plasma lipids by ~32%. Finally, we demonstrate that our episomal nonviral vectors are able to reduce atherosclerosis by ~40% after 12 weeks in vivo. Taken together, the vector system we describe exploits the normal cellular regulation of the LDLR to provide prolonged expression of LDLR through targeted knockdown of Hmgcr. This novel gene therapy system could act alone, or in synergy with current therapies that modulate intracellular cholesterol, such as statins, greatly enhancing its therapeutic application for FH.

Obesity, Inflammation, and Exercise Training: Relative Contribution of iNOS and eNOS in the Modulation of Vascular Function in the Mouse Aorta

Background: The understanding of obsesity-related vascular dysfunction remains controversial mainly because of the diseases associated with vascular injury. Exercise training is known to prevent vascular dysfunction. Using an obesity model without comorbidities, we aimed at investigating the underlying mechanism of vascular dysfunction and how exercise interferes with this process.

Methods: High-sugar diet was used to induce obesity in mice. Exercise training was performed 5 days/week. Body weight, energy intake, and adipose tissues were assessed; blood metabolic and hormonal parameters were determined; and serum TNFα was measured. Blood pressure and heart rate were assessed by plethysmography. Changes in aortic isometric tension were recorded on myograph. Western blot was used to analyze protein expression. Nitric oxide (NO) was evaluated using fluorescence microscopy. Antisense oligodeoxynucleotides were used for inducible nitric oxide synthase isoform (iNOS) knockdown.

Results: Body weight, fat mass, total cholesterol, low-density lipoprotein cholesterol fraction, insulin, and leptin were higher in the sedentary obese group (SD) than in the sedentary control animals (SS). Exercise training prevented these changes. No difference in glucose tolerance, insulin sensitivity, blood pressure, and heart rate was found. Decreased vascular relaxation and reduced endothelial nitric oxide synthase (eNOS) functioning in the SD group were prevented by exercise. Contractile response to phenylephrine was decreased in the aortas of the wild SD mice, compared with that of the SS group; however, no alteration was noted in the SD iNOS^−/− animals. The decreased contractility was endothelium-dependent, and was reverted by iNOS inhibition or iNOS silencing. The aortas from the SD group showed increased basal NO production, serum TNFα, TNF receptor-1, and phospho-IκB. Exercise training attenuated iNOS-dependent reduction in contractile response in high-sugar diet–fed animals, decreased iNOS expression, and increased eNOS expression.

Conclusion: Obesity caused endothelium dysfunction, TNFα, and iNOS pathway up-regulation, decreasing vascular contractility in the obese animals. Exercise training was an effective therapy to control iNOS-dependent NO production and to preserve endothelial function in obese individuals.

Do the Apoe-/- and Ldlr-/- Mice Yield the Same Insight on Atherogenesis?

Murine models of atherosclerosis are useful for investigating the environmental and genetic influences on lesion formation and composition. Apoe(-/-) and Ldlr(-/-) mice are the 2 most extensively used models. The models differ in important ways with respect to the precise mechanism by which their absence enhances atherosclerosis, including differences in plasma lipoproteins. The majority of the gene function studies have utilized only 1 model, with the results being generalized to atherogenic mechanisms. In only a relatively few cases have studies been conducted in both atherogenic murine models. This review will discuss important differences between the 2 atherogenic models and will point out studies that have been performed in the 2 models where results are comparable and those where different results were obtained.

Ameliorating effect of Allium Sativum on high-fat diet induced fatty liver in albino rats

Objective:

To assess the hepatoprotective effect provided by fresh garlic on fatty liver induced by high-fat diet.

Methods:

This experimental study was carried out at BMSI, JPMC from October to November 2008. Thirty adult albino rats, 200-240 gram weight, were divided into three groups. Group A received control diet, Group B received high-fat diet (20 mg butter/100 gm diet) and Group C received high-fat diet with fresh garlic (20 mg butter with 6 gm fresh garlic/100 gm diet). The groups were further divided on the basis of duration of treatment, four weeks and eight weeks respectively. The rats were sacrificed, liver removed, weighed and relative liver weight calculated. Hepatic tissue was processed and tissue slides stained with haematoxylin and eosin.

Results:

There was significant increase in relative liver weight in group B animals as compared to the control animals, which decreased significantly in group C. Haematoxylin and eosin stained sections revealed ballooned hepatocytes having vesicular appearance with pyknotic nuclei in high-fat group which were preserved to a great extent in group C animals.

Conclusion:

This study has shown that use of fresh garlic along with high-fat diet prevents its damaging effects on liver to a great extent.

Hypertension and decreased aortic compliance due to reduced elastin amounts do not increase atherosclerotic plaque accumulation in Ldlr-/- mice

BACKGROUND AND AIMS

High blood pressure and reduced aortic compliance are associated with increased atherosclerotic plaque accumulation in humans. Animal studies support these associations, but additional factors, such as fragmented elastic fibers, are present in most previous animal studies. Elastin heterozygous (Eln+/-) mice have high blood pressure and reduced aortic compliance, with no evidence of elastic fiber fragmentation and represent an appropriate model to directly investigate the effects of these factors on atherosclerosis.

METHODS AND RESULTS

Eln+/- and Eln+/+ mice were crossed with low density lipoprotein receptor knockout (Ldlr-/-) and wild-type (Ldlr+/+) mice and fed normal or Western diet (WD) for 16 weeks. We hypothesized that on WD, Eln+/-Ldlr-/- mice with high blood pressure and reduced aortic compliance would have increased atherosclerotic plaque accumulation compared to Eln+/+Ldlr-/- mice. We measured serum cholesterol and cytokine levels, blood pressure, aortic compliance, and plaque accumulation. Contrary to our hypothesis, we found that on WD, Eln+/-Ldlr-/- mice do not have increased plaque accumulation compared to Eln+/+Ldlr-/- mice. At the aortic root, there are no significant differences in plaque area between Eln+/-Ldlr-/- and Eln+/+Ldlr-/- mice on WD (p = 0.89), while in the ascending aorta, Eln+/-Ldlr-/- mice on WD have 29% less normalized plaque area than Eln+/+Ldlr-/- mice on WD (p = 0.009).

CONCLUSION

Using an atherogenic mouse model, we conclude that increased blood pressure and reduced aortic compliance are not direct causes of increased aortic plaque accumulation. We propose that additional insults, such as fragmentation of elastic fibers, are necessary to alter plaque accumulation.

Use of Mouse Models in Atherosclerosis Research

Cardiovascular disease is the major cause of death in most developed nations and the social and economic burden of this disease is quite high. Atherosclerosis is a major underlying basis for most cardiovascular diseases including myocardial infarction and stroke. Genetically modified mouse models, particularly mice deficient in apoprotein E or the LDL receptor, have been widely used in preclinical atherosclerosis studies to gain insight into the mechanisms underlying this pathology. This chapter reviews several mouse models of atherosclerosis progression and regression as well as the role of immune cells in disease progression and the genetics of murine atherogenesis.

Early onset intrauterine growth restriction in a mouse model of gestational hypercholesterolemia and atherosclerosis

The susceptibility to develop atherosclerosis is increased by intrauterine growth restriction and prenatal exposure to maternal hypercholesterolemia. Here, we studied whether mouse gestational hypercholesterolemia and atherosclerosis affected fetal development and growth at different stages of gestation. Female LDLR KO mice fed a proatherogenic, high cholesterol (HC) diet for 3 weeks before conception and during pregnancy exhibited a significant increase in non-HDL cholesterol and developed atherosclerosis. At embryonic days 12.5 (E12.5), E15.5, and E18.5, maternal gestational hypercholesterolemia and atherosclerosis were associated to a 22-24% reduction in male and female fetal weight without alterations in fetal number/litter or morphology nor placental weight or structure. Feeding the HC diet exclusively at the periconceptional period did not alter fetal growth, suggesting that maternal hypercholesterolemia affected fetal weight only after implantation. Vitamin E supplementation (1,000 UI of α-tocopherol/kg) of HC-fed females did not change the mean weight of E18.5 fetuses but reduced the percentage of fetuses exhibiting body weights below the 10th percentile of weight (HC: 90% vs. HC/VitE: 68%). In conclusion, our results showed that maternal gestational hypercholesterolemia and atherosclerosis in mice were associated to early onset fetal growth restriction and that dietary vitamin E supplementation had a beneficial impact on this condition.

Atheroprotective immunization with malondialdehyde-modified LDL is hapten specific and dependent on advanced MDA adducts: implications for development of an atheroprotective vaccine

Immunization with homologous malondialdehyde (MDA)-modified LDL (MDA-LDL) leads to atheroprotection in experimental models supporting the concept that a vaccine to oxidation-specific epitopes (OSEs) of oxidized LDL could limit atherogenesis. However, modification of human LDL with OSE to use as an immunogen would be impractical for generalized use. Furthermore, when MDA is used to modify LDL, a wide variety of related MDA adducts are formed, both simple and more complex. To define the relevant epitopes that would reproduce the atheroprotective effects of immunization with MDA-LDL, we sought to determine the responsible immunodominant and atheroprotective adducts. We now demonstrate that fluorescent adducts of MDA involving the condensation of two or more MDA molecules with lysine to form malondialdehyde-acetaldehyde (MAA)-type adducts generate immunodominant epitopes that lead to atheroprotective responses. We further demonstrate that a T helper (Th) 2-biased hapten-specific humoral and cellular response is sufficient, and thus, MAA-modified homologous albumin is an equally effective immunogen. We further show that such Th2-biased humoral responses per se are not atheroprotective if they do not target relevant antigens. These data demonstrate the feasibility of development of a small-molecule immunogen that could stimulate MAA-specific immune responses, which could be used to develop a vaccine approach to retard or prevent atherogenesis.

An accelerated mouse model for atherosclerosis and adipose tissue inflammation

Background

Obesity and particularly the metabolic syndrome, which is often associated with obesity, combine a major risk for type 2 diabetes and cardiovascular disease. Emerging evidence indicate obesity-associated subclinical inflammation primarily originating from adipose tissue as a common cause for type 2 diabetes and cardiovascular disease. However, a suitable and well-characterized mouse model to simultaneously study obesity-associated metabolic disorders and atherosclerosis is not available yet. Here we established and characterized a murine model combining diet-induced obesity and associated adipose tissue inflammation and metabolic deteriorations as well as atherosclerosis, hence reflecting the human situation of cardio-metabolic disease.

Methods

We compared a common high-fat diet with 0.15% cholesterol (HFC), and a high-fat, high-sucrose diet with 0.15% cholesterol (HFSC) fed to LDL receptor-deficient (LDLR^-/-) mice. Insulin resistance, glucose tolerance, atherosclerotic lesion formation, hepatic lipid accumulation, and inflammatory gene expression in adipose tissue and liver were assessed.

Results

After 12–16 weeks, LDLR^-/- mice fed HFSC or HFC developed significant diet-induced obesity, adipose tissue inflammation, insulin resistance, and impaired glucose tolerance compared to lean controls. Notably, HFSC-fed mice developed significantly higher adipose tissue inflammation in parallel with significantly elevated atherosclerotic lesion area compared to those on HFC. Moreover, LDLR^-/- mice on HFSC showed increased insulin resistance and impaired glucose tolerance relative to those on HFC. After prolonged feeding (20 weeks), however, no significant differences in inflammatory and metabolic parameters as well as atherosclerotic lesion formation were detectable any more between LDLR^-/- mice fed HFSC or HFC.

Conclusion

The use of high sucrose rather than more complex carbohydrates in high-fat diets significantly accelerates development of obesity-driven metabolic complications and atherosclerotic plaque formation parallel to obesity-induced adipose tissue inflammation in LDLR^-/- mice. Hence LDLR^-/- mice fed high-fat high-sucrose cholesterol-enriched diet appear to be a suitable and time-saving animal model for cardio-metabolic disease. Moreover our results support the suggested interrelation between adipose tissue inflammation and atherosclerotic plaque formation.

Quantitative analysis and characterization of atherosclerotic lesions in the murine aortic sinus

Atherosclerosis is a disease of the large arteries and a major underlying cause of myocardial infarction and stroke. Several different mouse models have been developed to facilitate the study of the molecular and cellular pathophysiology of this disease. In this manuscript we describe specific techniques for the quantification and characterization of atherosclerotic lesions in the murine aortic sinus and ascending aorta. The advantage of this procedure is that it provides an accurate measurement of the cross-sectional area and total volume of the lesion, which can be used to compare atherosclerotic progression across different treatment groups. This is possible through the use of the valve leaflets as an anatomical landmark, together with careful adjustment of the sectioning angle. We also describe basic staining methods that can be used to begin to characterize atherosclerotic progression. These can be further modified to investigate antigens of specific interest to the researcher. The described techniques are generally applicable to a wide variety of existing and newly created dietary and genetically-induced models of atherogenesis.

Dietary phytosterol does not accumulate in the arterial wall and prevents atherosclerosis of LDLr-KO mice

SCOPE

There have been conflicting reports on the usefulness of phytosterols (PS) in preventing atherosclerosis. We evaluated the effects of dietary PS supplementation in LDLr-KO male mice on the plasma and aorta sterol concentrations and on atherosclerotic lesion development.

METHODS AND RESULTS

Mice were fed a high fat diet (40% of energy) supplemented with or without PS (2% w/w, n = 10). Plasma and arterial wall cholesterol and PS concentrations, lesion area, macrophage infiltration, and mRNA expression from LOX-1, CD36, ABCA1 and ABCG1 in peritoneal macrophages were measured. After 16 weeks, the plasma cholesterol concentration in PS mice was lower than that in the controls (p = 0.02) and in the arterial wall (p = 0.03). Plasma PS concentrations were higher in PS-fed animals than in controls (p < 0.0001); however, the arterial wall PS concentration did not differ between groups. The atherosclerotic lesion area in the PS group (n = 5) was smaller than that in controls (p = 0.0062) and the macrophage area (p = 0.0007). PS correlates negatively with arterial lipid content and macrophage (r = -0.76; p < 0.05). PS supplementation induced lower ABCG1 mRNA expression (p < 0.05).

CONCLUSIONS

Despite inducing an increase in PS plasma concentration, PS supplementation is not associated with its accumulation in the arterial wall and prevents atherosclerotic lesion development.

Hypolipidemic and antioxidant properties of phenolic compound-rich extracts from white ginseng (Panax ginseng) in cholesterol-fed rabbits

In this study, the effect of low-molecular weight white ginseng compounds on various biochemical indices, including blood lipid concentrations and antioxidant enzyme activities and morphological changes was investigated in rabbits with high cholesterol diet-induced hypercholesterolemia. The experimental animals were 16-week-old male New Zealand white rabbits divided into normal control diet, high cholesterol diet, and high cholesterol with 0.05% white ginseng low-molecule compound groups, treated for 4 weeks. Blood lipid concentrations were higher in the high cholesterol groups compared to the normal control group but were not improved by the white ginseng low-molecular weight compound. We note however that antioxidant enzyme activities and morphological changes of the aorta showed that white ginseng small compounds had a positive effect on hypercholesterolemia. Based on such results, low-molecular weight compounds rich in phenolic compounds in white ginseng can be said to be effective in part in improving hyperlipidemia and atherosclerosis induced by a high cholesterol diet among New Zealand white rabbits.

Distinct metabolic and vascular effects of dietary triglycerides and cholesterol in atherosclerotic and diabetic mouse models

Cholesterol and triglyceride-rich Western diets are typically associated with an increased occurrence of type 2 diabetes and vascular diseases. This study aimed to assess the relative impact of dietary cholesterol and triglycerides on glucose tolerance, insulin sensitivity, atherosclerotic plaque formation, and endothelial function. C57BL6 wild-type (C57) mice were compared with atherosclerotic LDLr(-/-) ApoB(100/100) (LRKOB100) and atherosclerotic/diabetic IGF-II × LDLr(-/-) ApoB(100/100) (LRKOB100/IGF) mice. Each group was fed either a standard chow diet, a 0.2% cholesterol diet, a high-fat diet (HFD), or a high-fat 0.2% cholesterol diet for 6 mo. The triglyceride-rich HFD increased body weight, glucose intolerance, and insulin resistance but did not alter endothelial function or atherosclerotic plaque formation. Dietary cholesterol, however, increased plaque formation in LRKOB100 and LRKOB100/IGF animals and decreased endothelial function regardless of genotype. However, cholesterol was not associated with an increase of insulin resistance in LRKOB100 and LRKOB100/IGF mice and, unexpectedly, was even found to reduce the insulin-resistant effect of dietary triglycerides in these animals. Our data indicate that dietary triglycerides and cholesterol have distinct metabolic and vascular effects in obese atherogenic mouse models resulting in dissociation between the impairment of glucose homeostasis and the development of atherosclerosis.

Human oxidation-specific antibodies reduce foam cell formation and atherosclerosis progression

OBJECTIVES

We sought to assess the in vivo importance of scavenger receptor (SR)-mediated uptake of oxidized low-density lipoprotein (OxLDL) in atherogenesis and to test the efficacy of human antibody IK17-Fab or IK17 single-chain Fv fragment (IK17-scFv), which lacks immunologic properties of intact antibodies other than the ability to inhibit uptake of OxLDL by macrophages, to inhibit atherosclerosis.

BACKGROUND

The unregulated uptake of OxLDL by macrophage SR contributes to foam cell formation, but the importance of this pathway in vivo is uncertain.

METHODS

Cholesterol-fed low-density lipoprotein receptor knockout (LDLR(-/-)) mice were treated with intraperitoneal infusion of human IK17-Fab (2.5 mg/kg) 3 times per week for 14 weeks. Because anti-human antibodies developed in these mice, LDLR(-/-)/low-density lipoprotein receptor Rag 1 double-knockout mice (lacking the ability to make immunoglobulins due to loss of T- and B-cell function) were treated with an adenoviral vector encoding adenovirus expressed (Adv)-IK17-scFv or control adenovirus-enhanced green fluorescent protein vector intravenously every 2 weeks for 16 weeks.

RESULTS

In LDLR(-/-) mice, infusion of IK17-Fab was able to sustain IK17 plasma levels for the first 8 weeks, but these diminished afterward due to increasing murine anti-IK17 antibody titers. Despite this, after 14 weeks, a 29% decrease in en face atherosclerosis was noted compared with phosphate-buffered saline-treated mice. In LDLR(-/-)/low-density lipoprotein receptor Rag 1 double-knockout mice, sustained levels of plasma IK17-scFv was achieved by Adv-IK17-scFv-mediated hepatic expression, which led to a 46% reduction (p < 0.001) in en face atherosclerosis compared with adenovirus-enhanced green fluorescent protein vector. Importantly, peritoneal macrophages isolated from Adv-IK17-scFv treated mice had decreased lipid accumulation compared with adenovirus-enhanced green fluorescent protein-treated mice.

CONCLUSIONS

These data support an important role for SR-mediated uptake of OxLDL in the pathogenesis of atherosclerosis and demonstrate that oxidation-specific antibodies reduce the progression of atherosclerosis, suggesting their potential in treating cardiovascular disease in humans.

Lipidomics identification of metabolic biomarkers in chemically induced hypertriglyceridemic mice

In this study, we aim to identify the potential biomarkers in hTG pathogenesis in schisandrin B-induced hTG mouse model. To investigate whether these identified biomarkers are only specific to schisandrin B-induced hTG mouse model, we also measured these biomarkers in a high fat diet (HFD)-induced hTG mouse model. We employed a LC/MS/MS-based lipidomic approach for the study. Mouse liver and serum metabolites were separated by reversed phase liquid chromatography. Metabolite candidates were identified by matching with marker retention times, isotope distribution patterns, and high-resolution MS/MS fragmentation patterns. Subsequently, target candidates were quantified by quantitative MS. In the schisandrin B-induced hTG mice, we found that the plasma fatty acids, diglyceroids, and phospholipids were significantly increased. Palmitic acid and stearic acid were increased in the plasma; oleic acid, linoleic acid, linolenic acid, arachidonic acid, and docosahexaenoic acid were increased in both the plasma and the liver. Acetyl-CoA, malonyl-CoA, and succinyl-CoA were increased only in the liver. The changes in levels of these identified markers were also observed in HFD-induced hTG mouse model. The consistent results obtained from both hTG models not only suggest novel biomarkers in hTG pathogenesis, but they also provide insight into the underlying mechanism of the schisandrin B-induced hTG.

Omega-6 polyunsaturated fatty acids prevent atherosclerosis development in LDLr-KO mice, in spite of displaying a pro-inflammatory profile similar to trans fatty acids

The development of atherosclerosis and the inflammatory response were investigated in LDLr-KO mice on three high-fat diets (40% energy as fat) for 16 weeks: trans (TRANS), saturated (SAFA) or ω-6 polyunsaturated (PUFA) fats. The following parameters were measured: plasma lipids, aortic root total cholesterol (TC), lesion area (Oil Red-O), ABCA1 content and macrophage infiltration (immunohistochemistry), collagen content (Picrosirius-red) and co-localization of ABCA1 and macrophage (confocal microscopy) besides the plasma inflammatory markers (IL-6, TNF-α) and the macrophage inflammatory response to lipopolysaccharide from Escherichia coli (LPS). As expected, plasma TC and TG concentrations were lower on the PUFA diet than on TRANS or SAFA diets. Aortic intima macrophage infiltration, ABCA1 content, and lesion area on PUFA group were lower compared to TRANS and SAFA groups. Macrophages and ABCA1 markers did not co-localize in the atherosclerotic plaque, suggesting that different cell types were responsible for the ABCA1 expression in plaques. Compared to PUFA, TRANS and SAFA presented higher collagen content and necrotic cores in atherosclerotic plaques. In the artery wall, TC was lower on PUFA compared to TRANS group; free cholesterol was lower on PUFA compared to TRANS and SAFA; cholesteryl ester concentration did not vary amongst the groups. Plasma TNF-α concentration on PUFA and TRANS-fed mice was higher compared to SAFA. No difference was observed in IL-6 concentration amongst groups. Regarding the macrophage inflammatory response to LPS, TRANS and PUFA presented higher culture medium concentrations of IL-6 and TNF-α as compared to SAFA. The PUFA group showed the lowest amount of the anti-inflammatory marker IL-10 compared to TRANS and SAFA groups. In conclusion, PUFA intake prevented atherogenesis, even in a pro-inflammatory condition.

Chronic ingestion of a Western diet increases O-linked-β-N-acetylglucosamine (O-GlcNAc) protein modification in the rat heart

AIMS

Protein O-GlcNAcylation is both a nutrient sensing and cellular stress response that mediates signal transduction in the heart. Chronically elevated O-GlcNAc has been associated with the development of cardiac dysfunction at both the cellular and organ levels in obesity, insulin resistance and diabetes. Development of these pathologies is often attributed to diets high in saturated fat and sugar (a "Western" diet; WES) but a role for O-GlcNAc in diet-induced cardiac dysfunction has not been established. The aims of this study were to examine the effect of chronic consumption of WES on cardiac O-GlcNAcylation and investigate associations of O-GlcNAc with cardiac function and markers of cellular stress.

MAIN METHODS

Young male rats received either a control diet (CON; n=9) or WES (n=8) diet for 52 weeks.

KEY FINDINGS

There was no evidence of cardiac dysfunction, advanced glycation endproduct (AGE) accumulation, pathological cardiac hypertrophy, calcium handling impairment, fibrosis or endoplasmic reticulum stress in WES hearts. However, cardiac O-GlcNAc protein, particularly in the higher molecular weight range, was significantly higher in WES hearts compared to CON (P<0.05). Protein levels of the enzymes that regulate O-GlcNAc attachment were not different between groups; thus, the increased O-GlcNAcylation in WES hearts appears to be due to increased nutrient availability rather than enzymatic regulation of cellular stress.

SIGNIFICANCE

These data suggest that diets high in saturated fat and sugar may contribute to the adverse effects of metabolic syndrome and diabetes by an O-GlcNAc-mediated process and that this may occur in the absence of overt cellular stress.

Hyperlipidemia and atherosclerotic lesion development in Ldlr-deficient mice on a long-term high-fat diet

Background

Mice deficient in the LDL receptor (Ldlr^−/− mice) have been widely used as a model to mimic human atherosclerosis. However, the time-course of atherosclerotic lesion development and distribution of lesions at specific time-points are yet to be established. The current study sought to determine the progression and distribution of lesions in Ldlr^−/− mice.

Methodology/Principal Findings

Ldlr-deficient mice fed regular chow or a high-fat (HF) diet for 0.5 to 12 months were analyzed for atherosclerotic lesions with en face and cross-sectional imaging. Mice displayed significant individual differences in lesion development when fed a chow diet, whereas those on a HF diet developed lesions in a time-dependent and site-selective manner. Specifically, mice subjected to the HF diet showed slight atherosclerotic lesions distributed exclusively in the aortic roots or innominate artery before 3 months. Lesions extended to the thoracic aorta at 6 months and abdominal aorta at 9 months. Cross-sectional analysis revealed the presence of advanced lesions in the aortic sinus after 3 months in the group on the HF diet and in the innominate artery at 6 to 9 months. The HF diet additionally resulted in increased total cholesterol, LDL, glucose, and HBA1c levels, along with the complication of obesity.

Conclusions/Significance

Ldlr-deficient mice on the HF diet tend to develop site-selective and size-specific atherosclerotic lesions over time. The current study should provide information on diet induction or drug intervention times and facilitate estimation of the appropriate locations of atherosclerotic lesions in Ldlr^−/− mice.