Diet-induced Hypercholesterolemia Research Articles

Plant-Derived Phenolics Inhibit the Accrual of Structurally Characterised Protein and Lipid Oxidative Modifications

Epidemiological data suggest that plant-derived phenolics beneficial effects include an inhibition of LDL oxidation. After applying a screening method based on 2,4-dinitrophenyl hydrazine- protein carbonyl reaction to 21 different plant-derived phenolic acids, we selected the most antioxidant ones. Their effect was assessed in 5 different oxidation systems, as well as in other model proteins. Mass-spectrometry was then used, evidencing a heterogeneous effect on the accumulation of the structurally characterized protein carbonyl glutamic and aminoadipic semialdehydes as well as for malondialdehyde-lysine in LDL apoprotein. After TOF based lipidomics, we identified the most abundant differential lipids in Cu++-incubated LDL as 1-palmitoyllysophosphatidylcholine and 1-stearoyl-sn-glycero-3-phosphocholine. Most of selected phenolic compounds prevented the accumulation of those phospholipids and the cellular impairment induced by oxidized LDL. Finally, to validate these effects in vivo, we evaluated the effect of the intake of a phenolic-enriched extract in plasma protein and lipid modifications in a well-established model of atherosclerosis (diet-induced hypercholesterolemia in hamsters). This showed that a dietary supplement with a phenolic-enriched extract diminished plasma protein oxidative and lipid damage. Globally, these data show structural basis of antioxidant properties of plant-derived phenolic acids in protein oxidation that may be relevant for the health-promoting effects of its dietary intake.

Apolipoprotein E4 Impairs Macrophage Efferocytosis and Potentiates Apoptosis by Accelerating Endoplasmic Reticulum Stress

Apolipoprotein (apo) E4 is a major genetic risk factor for a wide spectrum of inflammatory metabolic diseases, including atherosclerosis, diabetes, and Alzheimer disease. This study compared diet-induced adipose tissue inflammation as well as functional properties of macrophages isolated from human APOE3 and APOE4 mice to identify the mechanism responsible for the association between apoE4 and inflammatory metabolic diseases. The initial study confirmed previous reports that APOE4 gene replacement mice were less sensitive than APOE3 mice to diet-induced body weight gain but exhibited hyperinsulinemia, and their adipose tissues were similarly inflamed as those in APOE3 mice. Peritoneal macrophages isolated from APOE4 mice were defective in efferocytosis compared with APOE3 macrophages. Increased cell death was also observed in APOE4 macrophages when stimulated with LPS or oxidized LDL. Western blot analysis of cell lysates revealed that APOE4 macrophages displayed elevated JNK phosphorylation indicative of cell stress even under basal culturing conditions. Significantly higher cell stress due mainly to potentiation of endoplasmic reticulum (ER) stress signaling was also observed in APOE4 macrophages after LPS and oxidized LDL activation. The defect in efferocytosis and elevated apoptosis sensitivity of APOE4 macrophages was ameliorated by treatment with the ER chaperone tauroursodeoxycholic acid. Taken together, these results showed that apoE4 expression causes macrophage dysfunction and promotes apoptosis via ER stress induction. The reduction of ER stress in macrophages may be a viable option to reduce inflammation and inflammation-related metabolic disorders associated with the apoE4 polymorphism.

Goldenberry (Physalis peruviana) Juice Rich in Health-Beneficial Compounds Suppresses High-Cholesterol Diet-Induced Hypercholesterolemia in Rats

Goldenberries (Physalis peruviana) are a promising exotic fruit that could be a subject of many novel foods. No reports are available on the effect of administration of goldenberries on different aspects of blood profile in experimental animals. The objective of this study was to investigate the effect of feeding goldenberry juice on hypercholesterolemia by analyzing the changes in the blood profile of high-cholesterol diet (HCD)-fed rats. The chemical composition and antiradical properties of juice were determined. Generally, rats fed with goldenberry juice showed lower levels of total cholesterol, total triacylglycerol and total low-density lipoprotein cholesterol, as well as higher levels of high-density lipoprotein cholesterol in comparison with animals fed with HCD and cholesterol-free diet. Juice administration induced a decrease in the activity of glutamic pyruvic transaminase compared with the positive control group after 2 months of administration. There was a remarkable decrease in total serum protein, albumin and globulin for groups treated with goldenberry juice. Histological examination of the liver and kidney were also conducted. The results demonstrated that consumption of goldenberry juice may provide beneficial effects on reversing HCD-associated detrimental changes.

Protective effect of α-Tocopherol on memory deficits and Na+,K+-ATPase and acetylcholinesterase activities in rats with diet-induced hypercholesterolemia

BackgroundWe investigate behavioral tests, acetylcholinesterase (AChE) and Na+,K+-ATPase activities in rats with diet-induced hypercholesterolemia feeding and α-tocopherol administration. MethodsWe tested a protocol with four groups: standard diet (control); high-fat diet (HF); α-tocopherol (α-Toc); HF plus α-tocopherol (HF+α-Toc). HF was administered ad libitum and α-Toc (50mg/kg) by gavage. After three months of treatment we performed the behavioral tests. The biochemical assays were performed ex vivo in the cerebral cortex (CC), hippocampus (HP) and blood samples. ResultsThe behavioral tests results showed a decrease in step-down latency for the HF group (P<0.05). When rats that received HF were treated with α-toc (HF+α-Toc) the step-down latency was similar to the control group. AChE and Na+,K+-ATPase activities in homogenate and synaptosomes was observed a significant decrease in CC and HP in HF group (P<0.05). However, α-Toc group showed to reverse the decline in AChE and Na+,K+-ATPase activities in CC and HP. HF group showed a significant increase (P<0.05) in MDA levels in CC and HP in relation to other groups. However, α-Toc group showed a significant decrease (P<0.05) in MDA levels when only compared with the HF group. Blood AChE activity increased in α-Toc group (P<0.05) and decreased in HF group (P<0.05) compared to all groups. ConclusionsThe present outcomes showed that treatment with α-Toc prevents the inhibition of AChE and Na+,K+-ATPase activities and consequently memory impairment induced by HF diet, demonstrating that this compound can modulate cholinergic neurotransmission and consequently improve cognition in this experimental condition.

Liraglutide and linagliptin improve glycemic control but show differential anti-obesity and hypolipidemic efficacy in a novel hamster model of diet-induced obesity and hypercholesterolemia

Liraglutide and linagliptin improve glycemic control but show differential anti-obesity and hypolipidemic efficacy in a novel hamster model of diet-induced obesity and hypercholesterolemia

Interferon-γ deficiency reduces neointimal formation in a model of endoluminal endothelial injury combined with atherogenic diet

Interferon (IFN)-γ has been implicated in restenosis, however its precise role in the pathophysiology of neointimal formation following angioplasty is unclear, as it has been shown to both promote and inhibit neointimal formation. Dietary-induced hypercholesterolemia enhances injury-mediated neointimal formation, associated with increased systemic inflammation and serum IFN-γ. This study examined the effect of IFN-γ gene deficiency ((-/-)) on neointimal formation in a mouse model of endothelial injury combined with an atherogenic diet. Neointimal formation was induced via endoluminal endothelial injury of the common iliac arteries of IFN-γ(-/-) and wild-type (WT) C57Bl/6 mice. Histopathological analysis of the arteries was performed at 3 and 6 weeks post-surgery. IFN-γ(-/-) mice demonstrated a significant reduction in neointimal formation at the 3-week time point, compared to their WT counterpart. No significant differences in plasma lipid profile and the extent of re-endothelialization were detected between IFN-γ(-/-) and WT mice, suggesting that the effect of IFN-γ on neointimal formation is due to injury-mediated vessel neointimal responses. In support of the histopathological findings, immunohistochemical analysis revealed a significant reduction in vessel infiltrating macrophages, and neointimal PDGF-B expression, vascular smooth muscle cell composition and cellular proliferation in the IFN-γ(-/-) mice, in comparison to their corresponding WT group at the 3-week time point. In conclusion, the IFN-γ-mediated pathway plays an important role in inflammatory responses and proliferative effects following injury, suggesting that modulation of the IFN-γ pathway would be beneficial in controlling neointimal formation and restenosis.

Tissue-specific knockouts of ACAT2 reveal that intestinal depletion is sufficient to prevent diet-induced cholesterol accumulation in the liver and blood

Acyl-CoA:cholesterol acyltransferase 2 (ACAT2) generates cholesterol esters (CE) for packaging into newly synthesized lipoproteins and thus is a major determinant of blood cholesterol levels. ACAT2 is expressed exclusively in the small intestine and liver, but the relative contributions of ACAT2 expression in these tissues to systemic cholesterol metabolism is unknown. We investigated whether CE derived from the intestine or liver would differentially affect hepatic and plasma cholesterol homeostasis. We generated liver-specific (ACAT2(L-/L-)) and intestine-specific (ACAT2(SI-/SI-)) ACAT2 knockout mice and studied dietary cholesterol-induced hepatic lipid accumulation and hypercholesterolemia. ACAT2(SI-/SI-) mice, in contrast to ACAT2(L-/L-) mice, had blunted cholesterol absorption. However, specific deletion of ACAT2 in the intestine generated essentially a phenocopy of the conditional knockout of ACAT2 in the liver, with reduced levels of plasma very low-density lipoprotein and hepatic CE, yet hepatic-free cholesterol does not build up after high cholesterol intake. ACAT2(L-/L-) and ACAT2(SI-/SI-) mice were equally protected from diet-induced hepatic CE accumulation and hypercholesterolemia. These results suggest that inhibition of intestinal or hepatic ACAT2 improves atherogenic hyperlipidemia and limits hepatic CE accumulation in mice and that depletion of intestinal ACAT2 is sufficient for most of the beneficial effects on cholesterol metabolism. Inhibitors of ACAT2 targeting either tissue likely would be beneficial for atheroprotection.

Abstract 129: Liver-Specific and Intestine-Specific ACAT2 Knockout Mice Are Equally Protected from Diet-Induced Hepatic Cholesterol Accumulation

Acyl-CoA:cholesterol acyltransferase 2 (ACAT2) is exclusively expressed in the small intestine and liver. ACAT2 facilitates the movement of cholesterol among tissues by generating cholesteryl ester (CE) for packaging into newly synthesized chylomicrons and very low-density lipoproteins (VLDL). In these studies we investigated whether CE derived from either the intestine or liver would differentially affect hepatic and plasma cholesterol homeostasis. For this purpose, we generated both liver-specific (ACAT2L-/L-) and intestine-specific (ACAT2SI-/SI-) ACAT2 knockout mice, and studied dietary cholesterol-induced hepatic lipid accumulation and hypercholesterolemia. Interestingly, diet-induced accumulation of hepatic CE was similarly decreased in both ACAT2L-/L- and ACAT2SI-/SI- mice, and free cholesterol did not build up in the liver. Compared with control mice, both ACAT2L-/L- and ACAT2SI-/SI- mice had lower levels of plasma VLDL-cholesterol but higher plasma triglycerides. ACAT2SI-/SI- but not ACAT2L-/L- mice had blunted cholesterol absorption. Collectively, both ACAT2L-/L- and ACAT2SI-/SI- mice were equally protected from diet-induced hepatic CE accumulation and hypercholesterolemia. These results suggest that inhibition of either intestinal or hepatic ACAT2 improves atherogenic hyperlipidemia and limits hepatic CE accumulation in mice, indicating that inhibition of ACAT2 expression in either tissue likely would be beneficial for atheroprotection.

Abstract 327: SR-BI Deficiency and Hypercholesterolemia Synergistically Lead to Impaired Erythropoiesis

Recent studies showed that mice deficient in scavenger receptor BI (SR-BI) exhibit impaired erythropoiesis and it has been proposed that the high cholesterol environment plays a major role in the abnormal erythropoiesis. In this study, we utilized three animal models to assess the role of SR-BI and hypercholesterolemia in erythropoiesis. First, we used a high fat diet-induced hypercholesterolemia model. High fat diet caused a 2-fold increase in plasma cholesterol levels in SR-BI +/+ (172 mg/dl to 350 mg/dl) and SR-BI -/- mice (313 mg/dl to 716 mg/dl). The high fat diet treatment markedly exacerbated the impaired erythropoiesis in SR-BI -/- mice as shown by 4-fold increase in reticulocyte percentage and 2.5-fold increase in early-to-late erythroblast ratio. Unexpectedly, high fat feeding did not induce abnormal erythropoiesis in SR-BI +/+ mice despite of hypercholesterolemia in these mice. We then used SR-BI/LDLR double knockout mice to further elucidate the contribution of hypercholesterolemia to erythropoiesis. SR-BI/LDLR double knockout mice had 2-fold increase in plasma cholesterol levels and exhibited severer impaired erythropoiesis, similar to high fat-fed SR-BI -/- mice. Interestingly, despite of hyperlipidemia, LDLR single knockout mice did not display impaired erythropoiesis. Finally, we investigated the contribution of hepatic SR-BI using ScarbI I179N mutant mice, whose hepatic SR-BI expression has been knocked down by 90% and therefore has a 1.7-fold increase in plasma cholesterol levels compared to wild type controls. ScarbI I179N mice displayed normal erythropoiesis, similar to wild type controls. These findings indicate that hypercholesterolemia does not cause abnormal erythropoiesis in the presence of SR-BI, but markedly impairs erythropoiesis in the absence of SR-BI. We conclude that SR-BI is essential for normal erythropoiesis, and that hypercholesterolemia and SR-BI deficiency synergistically exacerbated impaired erythropoiesis.

GPSE (GRAPE SEED PROANTHOCYANIDIN EXTRACT) SIMVASTATIN AND SILYMARIN EFFECT ON HIGH CHOLESTEROL-FED ANIMALS

The present study was designed to test the hypothesis that cholesterol rich diet-induced hypercholesterolemia in rabbits can be reversed by long-term treatment of antioxidants (proanthocyanidin and silymarin) and antihyperlipidemic drug(simvastatin). In this study 35 adult New Zealand White (NZW) male rabbits were used and divided into five groups. The rabbits in Group 1(control) was fed with rabbit chow diet. Group 2 was fed with only cholesterol (2% w/w) rich diet to induce hypercholesterolemia. The other groups received GPSE 100mg/kg (Group 3), silymarin 10mg/kg (Group 4) and simvastatin10mg/kg (Group 5) with cholesterol in addition to rabbit chow diet. At the end of the experiment, the animals were sacrified and their aorta were excised for intimal lesion analysis. Vessells were dissected, trimmed, and then placed fixed in neutral formalin. All tissue sections were stained with hematoxylin and eosin(H&E). Apoptotic process was detected by using TUNEL. Cholesterol treatment produced a sustainable state of atheromatous plaque formation In addition, only cholesterol rich diet-induced animals have shown a considerably high number apoptotic cells by using TUNEL and plasma total cholesterol (TC) and low density lipoprotein (LDL) levels were found.

Hypercholesterolemia accelerates intraneuronal accumulation of Aβ oligomers resulting in memory impairment in Alzheimer's disease model mice

AimsHypercholesterolemia is known to be a risk factor for Alzheimer's disease (AD), and diet-induced hypercholesterolemia has been shown to accelerate amyloid pathology in animals. While growing evidence has shown that synaptic and cognitive dysfunction in AD is associated with intraneuronal accumulation of Aβ, the relationships between hypercholesterolemia, memory impairment, and intraneuronal Aβ remains unclear. The present study aims to clarify this association. Main methodsTransgenic mice expressing amyloid precursor protein (APP) harboring the Osaka (E693∆) mutation (APPOSK-Tg mice) were used. These mice exhibit intraneuronal Aβ oligomers and memory impairment from 8months of age. Five-month-old male APPOSK-Tg mice and non-Tg littermates were fed a high-cholesterol diet for 1month to induce hypercholesterolemia. At 6months of age, their cognitive function was evaluated by the Morris water maze. Intraneuronal Aβ, synaptic density, and tau phosphorylation were examined by immunohistochemistry. Key findingsSerum and brain cholesterol levels were significantly higher in APPOSK-Tg mice and non-Tg littermates that were fed a high-cholesterol diet than in control mice that were fed normal chow, indicating that hypercholesterolemia was successfully induced. Hypercholesterolemic APPOSK-Tg mice, but not control APPOSK-Tg mice or hypercholesterolemic non-Tg littermates, exhibited impaired spatial reference memory, which was accompanied with intraneuronal accumulation of Aβ oligomers, reduced synaptophysin immunoreactivity, and abnormal tau phosphorylation in the hippocampus. Hypercholesterolemia-accelerated accumulation of intraneuronal Aβ oligomers was also observed in another model mouse, Tg2576. SignificanceOur findings suggest that hypercholesterolemia accelerates intraneuronal accumulation of Aβ oligomers and subsequent synapse loss, resulting in memory impairment.

Anthocyanin‐rich red cabbage (Brassica oleracea L.) extract attenuates cardiac and hepatic oxidative stress in rats fed an atherogenic diet

Oxidative stress induced by reactive oxygen species plays an important role in the aetiology of several diseases including atherosclerosis and coronary heart disease. Anthocyanin-rich extracts have been shown to possess a variety of therapeutic roles, including antioxidant, cardioprotective and hepatoprotective properties. The present inventory was undertaken to evaluate the protective role of anthocyanin-rich red cabbage extract (ARCE) on an atherogenic (ATH) diet-induced hypercholesterolaemia and related cardiac and, hepatic oxidative stress in rats. ARCE (100 mg kg(-1) body weight) treatment of rats fed the ATH diet significantly prevented elevation in serum and tissue lipids, circulating levels of cardiac and hepatic damage markers, and resulted in excretion of lipids through faeces. Also, the ARCE extract significantly attenuated alterations in the cardiac and hepatic antioxidants and lipid peroxidation, and histopathological changes in cardiac and hepatic tissue. Thus, the present study provides the first scientific evidence for a protective role of ARCE against ATH diet-induced hypercholesterolaemia and cardiac and hepatic oxidative stress.

Naringin at a nutritional dose modulates expression of genes related to lipid metabolism and inflammation in liver of mice fed a high-fat diet

Epidemiological and clinical studies a role for flavanones (predominately found in citrus fruits) in the prevention of cardiovascular disease. Previously, we have shown that a nutritional dose of naringin exerts anti-atherogenic properties together with non HDL-cholesterol lowering effect in a murin model of dietary-induced hypercholesterolemia (1). The goal of the present study was to explore possible molecular mechanisms of naringin at the hepatic level. To this end, we analyzed the hepatic transcriptome using a microarray approach in response to naringin supplementation (0.02%) in mice fed a high-fat high- cholesterol diet. Naringin was observed to increase hepatic lipid content (triglyceride and cholesterol) without significant liver dysfunction (ALAT and ASAT activities) or histopathological alterations. Naringin supplementation also significantly improved insulin sensitivity as evaluated by the HOMA index and nutrigenomics revealed that naringin modulated the expression of 1,766 genes. These genes encode proteins involved in different cellular processes, such as lipid metabolism, inflammation and insulin signaling. In conclusion, this study revealed that the hypolipemic and anti-atherogenic effects induced by a nutritional- level naringin supplementation in high-fat high-cholesterol diet could be related to changes in hepatic lipid metabolism and inflammatory response, revealing new in vivo targets of this flavanone.

KB-R7943 Reduces Necrosis and Apoptosis in Hyperlipidemic Animals through the Activation of K+ATP Channels

Reverse-mode activation of the Na+-Ca2+ exchanger (NCX) at the time of reperfusion following ischemia contributes to Ca2+ overload and cardiomyocyte injury, KB-R7943, as a selective reverse-mode NCX inhibitor, reduces lethal reperfusion injury under normal conditions, but its effectiveness under certain pathological states is in dispute. In the present study, we sought to determine the effect of KB-R7943 in hyperlipidemic animals and assess if the K+ ATP are involved in the protective mechanisms. Anesthetized rats were randomized into five groups, as follows, and were subjected to 25min global ischemia (GI) followed by 120 min reperfusion (R). Normally fed animals: a Control group (NC) with no additional intervention. Cholesterol fed (6weeks) animals: a Chol group (HC) with no additional interventions, a KB-R7943 group (HKB) treated with KB-R7943, a KB-R7943 and glybenclamide group (HGKB) treated with KB-R7943 and glybenclamide (K+ ATP, blocker, 0.3μM), a glybenclamide group (HGLY) treated with glybenclamide The infarct size was measured by triphenyltetrazolium. The infarct size was 35±5.0% in NC, 46±8.7% in HC and 47±8.5% in HGLY (NC vs. HC, P 0.05). KB-R7943 reduced the infarct size (28.6±3.3% in HKB vs. HC, P<0.05), In addition, KB-R7943 attenuated apoptotic cell (HKB vs. HC, p<0.05), glybenclamide abolished the effect reached by KB-R7943. Thus, diet-induced hypercholesterolemia enhances myocardial injury; KB-R7943 reduces infarct size and apoptosis in hyperlipidemic animals through the activation of K+ ATP channels.

Cholesterol esterification by ACAT2 is essential for efficient intestinal cholesterol absorption: evidence from thoracic lymph duct cannulation

The hypothesis tested in this study was that cholesterol esterification by ACAT2 would increase cholesterol absorption efficiency by providing cholesteryl ester (CE) for incorporation into chylomicrons. The assumption was that absorption would be proportional to Acat2 gene dosage. Male ACAT2⁺/⁺, ACAT2⁺/⁻, and ACAT2⁻/⁻ mice were fed a diet containing 20% of energy as palm oil with 0.2% (w/w) cholesterol. Cholesterol absorption efficiency was measured by fecal dual-isotope and thoracic lymph duct cannulation (TLDC) methods using [³H]sitosterol and [¹⁴C]cholesterol tracers. Excellent agreement among individual mice was found for cholesterol absorption measured by both techniques. Cholesterol absorption efficiency in ACAT2⁻/⁻ mice was 16% compared with 46-47% in ACAT2⁺/⁺ and ACAT2⁺/⁻ mice. Chylomicrons from ACAT2⁺/⁺ and ACAT2⁺/⁻ mice carried ∼80% of total sterol mass as CE, whereas ACAT2⁻/⁻ chylomicrons carried >90% of sterol mass in the unesterified form. The total percentage of chylomicron mass as CE was reduced from 12% in the presence of ACAT2 to ∼1% in ACAT2⁻/⁻ mice. Altogether, the data demonstrate that ACAT2 increases cholesterol absorption efficiency by providing CE for chylomicron transport, but one copy of the Acat2 gene, providing ∼50% of ACAT2 mRNA and enzyme activity, was as effective as two copies in promoting cholesterol absorption.

Suppression of Diet-Induced Hypercholesterolemia by Turtle Jelly, A Traditional Chinese Functional Food, in Rats

Consumption of functional foods for lowering serum cholesterol has globally gained acceptance by the general public. Turtle jelly (TJ), also called gui-ling-gao, is a popular traditional functional food in southern China. The hypocholesterolemic effect of consuming TJ was investigated in rats fed with normal diet, high-cholesterol diet or high-cholesterol diet supplemented with simvastatin (3 mg/kg bw per day, p.o.) or TJ (3.3 or 10 mL/kg bw per day, p.o.) for 30 days. TJ markedly reversed the increased serum total cholesterol, increased high-density lipoprotein, and decreased high-density lipoprotein induced by hypercholesterolemic diet with a dose-dependent improvement on the atherogenic index. It also demonstrated good hepatoprotective function by reducing fat depositions and overall lipid contents in the liver and increasing the activities of hepatic antioxidative enzymes. The blunted nitric oxide/endothelium-mediated aortic relaxation in rats fed with hypercholesterolemic diet was partially restored after TJ consumption. It is postulated that the hypocholesterolemic effect is the primary beneficial effect given by TJ; it then leads to secondary beneficial effects such as vasoprotective and hepatoprotective functions. The results revealed that TJ could block the downregulation of LDLR and PEPCK and upregulation of PPARα mRNA and protein expressions in the livers of rats fed with hypercholesterolemic diet.

Immune Modulation of Atherosclerosis

The notion that inflammation plays a role in atherosclerosis dates to separate observations by Virchow and von Rokitansky in the middle of the 19 th century that atherosclerotic blood vessels contained evidence of cellular inflammation. This concept remained stagnant until the 1970s, when Russell Ross demonstrated that monocyte adhesion to the endothelial surface was an early and essential feature of atherosclerosis.1 These observations, coupled with knowledge that modified low-density lipoprotein (LDL) supports foam cell formation and promotes atherosclerosis disease activity,2 focused early investigative efforts on monocytes and macrophages, the foam cell precursors. Indeed, it is clear that neutrophils3 and monocytes enter lesion-prone arterial sites, the latter differentiate into macrophages, and then take up accumulated LDL-cholesterol to form foam cells and early atherosclerotic lesions. Innate immune responses, such as recognition of modified LDL-derived epitopes via macrophage Toll-like receptors, prompts cytokine-mediated recruitment of other inflammatory cells to the lesion4 that, in turn, promote the adaptive immune responses responsible for the chronic inflammation of atherosclerosis. Emerging evidence has helped to refine this paradigm and identify critical events in adaptive immunity that could represent therapeutic opportunities for immune modulation of atherosclerosis. Activated endothelium is characterized by adhesion molecule expression and reduced barrier function that mediate the recruitment of both monocytes5 and T-cells into lesion-prone sites in the arterial wall. With regard to T-cells, histological examination of atherosclerotic lesions demonstrate the presence of both CD4+ T helper (Th) cells, CD8+ cytotoxic T (Tc) cells, and regulatory T cells (Treg) in lesions, although Th cells generally predominate. Lesional T-cells represent a cellular minority …

Expression of the human apoE2 isoform in adipocytes: altered cellular processing and impaired adipocyte lipogenesis

Expression of apoE in adipocytes has been shown to have an important role in modulating adipocyte triglyceride (TG) metabolism and gene expression that is independent of circulating and extracellular apoE. The impact of adipocyte expression of common human apoE isoforms was evaluated using adipocytes harvested from human apoE2, -3, and -4 knock-in mice. Expression of the apoE2 isoform was associated with an increase in adipocyte apoE gene expression and apoE synthesis. Newly synthesized apoE2 was unstable in adipocytes and demonstrated increased degradation and decreased secretion. ApoE2-expressing mice were hyperlipidemic, and had increased size of gonadal fat pads and of adipocytes, compared with apoE3 mice. In isolated cells, however, expression of the apoE2 isoform produced defective lipogenesis and increased TG hydrolysis. Incubation of adipose tissue with apoE3-containing TG-rich lipoproteins resulted in a significant increase in TG in adipose tissue from apoE3 and -E4 mice, but not apoE2 mice. Reduced capacity to internalize FFA as lipogenic substrate contributed to defective lipogenesis. Newly synthesized apoE2 is unstable in adipocytes and results in decreased adipocyte TG synthesis and defective FA uptake. These changes recapitulate those observed in apoE knockout adipocytes and have implications for understanding metabolic disturbances in humans expressing the E2 isoform.

Effects of long-term consumption of low doses of resveratrol on diet-induced mild hypercholesterolemia in pigs: a transcriptomic approach to disease prevention

Metabolic and cardiovascular diseases (CVDs) have risen to alarming proportions, and there is a need for therapeutic and preventive measures. The polyphenol resveratrol (RES) protects against CVDs, but in vivo molecular mechanisms responsible for protection are not yet understood. Peripheral blood mononuclear cells (PBMNCs) are involved in the development of atherosclerosis and metabolic disorders. The identification of PBMNCs genes responding to dietary compounds might help to understand the mechanisms underlying the effects of polyphenols. We determined gene expression differences between PBMNCs from pigs fed a high-fat diet manifesting a mild increase of cholesterol and pigs fed a high-fat diet containing low doses of RES. Although the consumption of RES did not modify the levels of cholesterol, microarray analyses indicated that some of the differentially expressed genes, collagens (COL1A, COL3A), lipoprotein lipase (LPL) and fatty-acid binding proteins (FABPs) involved in CVDs and lipid metabolism were up-regulated by the high-fat diet and down-regulated by RES. Reverse transcriptase polymerase chain reaction confirmed that RES and RES-containing grape extract prevented the induction of FABP4 in PBMNCs in female pigs fed a high-fat diet. Low micromolar concentrations of RES and its metabolite dihydroresveratrol exerted a minor but significant reducing effect on the induction of FABP4 expression in human macrophages treated with oxidized low-density lipoprotein. Our results show that the consumption of low doses of RES modulates the expression of genes related to lipid metabolism and metabolic disorders that are affected by a high-fat diet and suggest that some of the circulating RES metabolites may contribute to these effects.

Hepatic Overexpression of Abcb11 Promotes Hypercholesterolemia and Obesity in Mice

ABCB11 is a canalicular transport protein that controls the rate-limiting step in hepatic bile acid secretion. Its expression levels vary in humans, and it is not clear how these variations affect lipid metabolism. We investigated whether overexpression of Abcb11 in mice increases lipid absorption in the intestine and affects the development of obesity or hypercholesterolemia. Transgenic mice that overexpress Abcb11 in liver (TTR-Abcb11) and FVB/NJ mice (controls) were fed a high-cholesterol or high-fat diet for 12 weeks. Intestinal lipid absorption was measured by the dual fecal isotope method. Energy expenditure was measured by indirect calorimetry. The bile acid pool was analyzed by high-performance liquid chromatography. TTR-Abcb11 mice had a nearly 2-fold increase in intestinal cholesterol absorption compared with controls. TTR-Abcb11 mice fed a high-cholesterol diet had greater increases in plasma and hepatic levels of cholesterol and became more obese than controls; they also had increased intestinal absorption of fatty acids and decreased energy expenditure. In the TTR-Abcb11 mice, the sizes of plasma and total bile acid pools were reduced; the bile acid pool contained more species of hydrophobic bile acids compared with controls. Hepatic overexpression of Abcb11 in mice promotes diet-induced obesity and hypercholesterolemia; increased intestinal cholesterol absorption by hydrophobic bile acids might cause these features. Increased absorption of fatty acids in the intestine and reduced expenditure of energy could increase weight gain in TTR-Abcb11 mice. In humans, variations in expression of ABCB11 might confer genetic susceptibility to diet-induced hyperlipidemia and obesity.