Abstract 3757: Targeted Inactivation of Receptor for Advanced Glycation Products Reduced Oxidative LDL-Induced Inflammation and Atherosclerosis in Non-Diabetic LDL Receptor−/− Mice

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Li Sun ◽  
Tatsuro Ishida ◽  
Masamitsu Kuriyama ◽  
Tomoyoki Yasuda ◽  
Tetsuya Hara ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Low Density Lipoprotein ◽  
Fasting Blood Glucose ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Peritoneal Macrophages ◽  
Advanced Glycation ◽  
Double Knockout ◽  
Erk Activation

Receptor for advanced glycation products (RAGE) is a multiligand receptor on vascular cells and plays an important role in the progression of diabetic complications. To define if RAGE modulates atherosclerosis under non-diabetic conditions, we examined the effect of RAGE deficiency in non-diabetic mice with hyperlipidemia. RAGE knockout mice (RAGE−/−) were bred with low-density lipoprotein receptor knockout (LDLr−/−) mice to generate the double knockout (DKO) mice. The mice were fed with western diet for 12 weeks, and aortic atherosclerotic lesions were analyzed histologically. Although there was no difference in body weight, fasting blood glucose and serum AGE levels between DKO and LDLr−/− mice, DKO mice exhibited a significant decrease in the size and macrophage content in atherosclerosis lesions compared with LDLr−/− mice. Expressions of endothelial adhesion molecules such as VCAM-1 and ICAM-1 in the aorta were lower in DKO mice than those in LDLr−/− mice. Chemiluminescence and fluorescence-based assays revealed that DKO mice showed lower oxidative stress in the vessel wall than LDLr−/− mice. Complementary in vitro studies revealed that peritoneal macrophages isolated from RAGE−/− mice exhibited a decrease in oxidative LDL (oxLDL)-induced ERK activation and proliferation when compared to RAGE+/+ macrophages. In contrast, overxpression of RAGE in COS7 cells resulted in the augmented ERK activation in response to oxLDL, which is abolished by the co-incubation with anti-RAGE blocking antibodies. The results indicated that oxLDL activated RAGE and increased oxidative stress via NADH/NADPH oxidase pathway. OxLDL may serve as a new ligand for RAGE. RAGE inactivation inhibits atherosclerosis by reducing pro-inflammatory and oxidative stress under the hyperlipidmic, non-diabetic condition.

Abstract 5: Lipid Droplet Associated Hydrolase: A New Player in Cholesterol Mobilization From Foam Cells

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Younghwa Goo ◽  
Pradip Saha ◽  
Larry Chan ◽  
Antoni Paul
Keyword(s):  
Lipid Droplet ◽  
Cholesterol Efflux ◽  
Bone Marrow Cells ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Foam Cells ◽  
Peritoneal Macrophages ◽  
Cholesterol Homeostasis

Lipid laden macrophages/foam cells are a hallmark of atherosclerotic lesions from early to late stages of development. Macrophages take-up modified low-density lipoprotein (mLDL) particles and store surplus mLDL-derived cholesterol as cholesterol ester (CE) in cytoplasmic lipid droplets (LDs). Accelerating CE hydrolysis from the LDs is a plausible strategy to promote reverse cholesterol transport from the atheroma. However, the identity of the CE hydrolases that function on LDs remains unknown. Previously we identified lipid droplet-associated hydrolase (LDAH) in LDs purified from macrophages and reported that in vitro LDAH regulates CE levels by increasing CE hydrolysis. To determine the relevance of LDAH in atherogenesis, we have generated LDAH knockout (LDAH-/-) mice. Mouse peritoneal macrophages (MPM) isolated from LDAH-/- mice had increased cytoplasmic LDs, increased net CE content, and decreased cholesterol efflux. In atherosclerosis studies, both male and female LDAH-/- mice crossed with apolipoprotein E knockout (apoE-/-) mice fed a Western diet developed larger lesions. Lesions of LDAH-/-/ apoE-/- mice were characterized by increased areas of macrophages containing enlarged cytoplasms with large LDs. Supporting a direct atheroprotective role of LDAH in macrophages, lesions of apoE-/- mice that received bone marrows from LDAH-/-/apoE-/- mice progressed faster than those that received bone marrow cells from LDAH+/+/apoE-/- mice. In qPCR analyses of genes involved in cholesterol homeostasis in macrophages, we found that ABC binding cassette transporters ABCA1 and ABCG1, which mediate cholesterol efflux through the plasma membrane, were consistently decreased in LDAH-/- MPM. Further in vivo gene expression studies on macrophages selectively obtained from lesions using laser capture microdissection are underway. In conclusion, our study suggests that LDAH promotes LD CE hydrolysis and cholesterol efflux from foam cells within the atheroma, and uncovers a potential target to promote reverse cholesterol from arteries as a means of ameliorating atherosclerosis development.

scholarly journals A novel peroxisome proliferator response element modulates hepatic low-density lipoprotein receptor gene transcription in response to PPARδ activation

2015 ◽  
Vol 472 (3) ◽  
pp. 275-286 ◽  
Author(s):  
Vikram R. Shende ◽  
Amar Bahadur Singh ◽  
Jingwen Liu
Keyword(s):  
Gene Transcription ◽  
Receptor Gene ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Peroxisome Proliferator ◽  
Density Lipoprotein Receptor ◽  
Peroxisome Proliferator Response Element

PPARδ activation beneficially regulates lipid metabolism. We have now identified a novel function of PPARδ that increases LDL receptor gene transcription in hepatic cells in vitro and in vivo through direct binding to a PPRE motif on LDLR promoter.

scholarly journals Pleurotus tuber-regiumPolysaccharides Attenuate Hyperglycemia and Oxidative Stress in Experimental Diabetic Rats

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Hui-Yu Huang ◽  
Mallikarjuna Korivi ◽  
Ying-Ying Chaing ◽  
Ting-Yi Chien ◽  
Ying-Chieh Tsai
Keyword(s):  
Oxidative Stress ◽  
Serum Insulin ◽  
Glycosylated Hemoglobin ◽  
Low Density Lipoprotein ◽  
Fasting Blood Glucose ◽  
Antioxidant Properties ◽  
Density Lipoprotein ◽  
Diabetic Rats ◽  
High Fat ◽  
And Oxidative Stress

Pleurotus tuber-regiumcontains polysaccharides that are responsible for pharmacological actions, and medicinal effects of these polysaccharides have not yet been studied in diabetic rats. We examined the antidiabetic, antihyperlipidemic, and antioxidant properties ofP. tuber-regiumpolysaccharides in experimental diabetic rats. Forty rats were equally assigned as diabetic high-fat (DHF) diet and polysaccharides treated DHF groups (DHF+1P, DHF+2P, and DHF+3P, 20 mg/kg bodyweight/8-week). Diabetes was induced by chronic low-dose streptozotocin injections and a high-fat diet to mimic type 2 diabetes. Polysaccharides (1P, 2P, and 3P) were extracted from three different strains ofP. tuber-regium. Fasting blood glucose and glycosylated hemoglobin (HbA1c) levels substantially decreased, while serum insulin levels were restored by polysaccharides treatment compared to DHF. Furthermore, plasma total cholesterol, triglycerides, and low-density lipoprotein levels were significantly(P<0.01)lower in polysaccharide groups. High-density lipoprotein levels were attenuated with polysaccharides against diabetes condition. Polysaccharides inhibited(P<0.01)the lipid peroxidation index (malondialdehyde), and restored superoxide dismutase and glutathione peroxidase activities in the liver of diabetic rats. The antihyperglycemic property of polysaccharides perhaps boosts the antioxidant system that attenuates oxidative stress. We emphasize thatP. tuber-regiumpolysaccharides can be considered as an alternative medicine to treat hyperglycemia and oxidative stress in diabetic rats.

scholarly journals Apigenin Attenuates Atherogenesis through Inducing Macrophage Apoptosis via Inhibition of AKT Ser473 Phosphorylation and Downregulation of Plasminogen Activator Inhibitor-2

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Ping Zeng ◽  
Bin Liu ◽  
Qun Wang ◽  
Qin Fan ◽  
Jian-Xin Diao ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Plasminogen Activator Inhibitor ◽  
Peritoneal Macrophages ◽  
Potential Binding Site ◽  
Induced Apoptosis ◽  
Activator Inhibitor

Macrophage survival is believed to be a contributing factor in the development of early atherosclerotic lesions. Dysregulated apoptosis of macrophages is involved in the inflammatory process of atherogenesis. Apigenin is a flavonoid that possesses various clinically relevant properties such as anti-inflammatory, antiplatelet, and antitumor activities. Here we showed that apigenin attenuated atherogenesis inapoE-/-mice in anin vivotest.In vitroexperiments suggested that apigenin induced apoptosis of oxidized low density lipoprotein- (OxLDL-) loaded murine peritoneal macrophages (MPMs). Proteomic analysis showed that apigenin reduced the expression of plasminogen activator inhibitor 2 (PAI-2). PAI-2 has antiapoptotic effects in OxLDL-loaded MPMs. Enhancing PAI-2 expression significantly reduced the proapoptosis effects of apigenin. Molecular docking assay with AutoDock software predicted that residue Ser473 of Akt1 is a potential binding site for apigenin. Lentiviral-mediated overexpression of Akt1 wild type weakened the proapoptosis effect of apigenin in OxLDL-loaded MPMs. Collectively, apigenin executes its anti-atherogenic effects through inducing OxLDL-loaded MPMs apoptosis. The proapoptotic effects of apigenin were at least partly attributed to downregulation of PAI-2 through suppressing phosphorylation of AKT at Ser473.

scholarly journals Receptor activities for low-density lipoprotein and acetylated low-density lipoprotein in a mouse macrophage cell line (IC21) and in human monocyte-derived macrophages.

1981 ◽  
Vol 154 (6) ◽  
pp. 1852-1867 ◽  
Author(s):  
M G Traber ◽  
V Defendi ◽  
H J Kayden
Keyword(s):  
Cholesteryl Ester ◽  
Cholesterol Synthesis ◽  
Low Density Lipoprotein ◽  
Primary Cultures ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Simian Virus 40 ◽  
Human Monocyte ◽  
Peritoneal Macrophages ◽  
Low Density

IC21 macrophages, a permanent culture of a line of cells derived from a single colony of mouse peritoneal macrophages transformed with simian virus 40, demonstrate most of the characteristics of lipoprotein metabolism that have been described for primary cultures of rodent or canine peritoneal macrophages. IC21 macrophages have low but demonstrable low-density lipoprotein (LDL) receptor activity. They actively degrade acetylated LDL (AcLDL), which has a negative charge and is not recognized by the LDL receptor. Incubation of IC21 macrophages with human lipoprotein-depleted serum leads to a marked increase in cholesterol synthesis, as measured by incorporation of labeled acetate into sterols. Sterol synthesis is inhibited by further incubation with AcLDL; incubation with LDL also decreases cholesterol synthesis with an accumulation of radioactivity from acetate in sterol intermediates, which indicates that some uptake of LDL occurs. Incubation with AcLDL but not LDL leads to a marked stimulation of cholesterol esterification, as measured by labeled oleic acid incorporation into cholesteryl esters, and a concomitant increase in cellular cholesteryl ester content. IC21 macrophages as compared with human monocyte-derived macrophages are shown to have marked difference in their abilities to degrade native LDL and AcLDL. Human monocyte-derived macrophages degrade LDL at low concentrations at a rate sevenfold greater than do IC21 macrophages. The rate of cholesteryl ester synthesis after LDL receptor induction and incubation with LDL increases linearly with LDL concentration in HMD macrophages, but no increase was found in similarly incubated IC21 macrophages. IC21 macrophages degrade AcLDL at a rate two- to fourfold greater than do human monocyte-derived macrophages.

scholarly journals In Vitro Assays for the Discovery of PCSK9 Autoprocessing Inhibitors

2016 ◽  
Vol 21 (10) ◽  
pp. 1034-1041 ◽  
Author(s):  
Scott P. Salowe ◽  
Lei Zhang ◽  
Hratch J. Zokian ◽  
Jennifer J. Gesell ◽  
Deborah L. Zink ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Resonance Energy Transfer ◽  
Density Lipoprotein ◽  
Resonance Energy ◽  
In Vitro Study ◽  
In Vitro Assays ◽  
Time Resolved

PCSK9 plays a significant role in regulating low-density lipoprotein (LDL) cholesterol levels and has become an important drug target for treating hypercholesterolemia. Although a member of the serine protease family, PCSK9 only catalyzes a single reaction, the autocleavage of its prodomain. The maturation of the proprotein is an essential prerequisite for the secretion of PCSK9 to the extracellular space where it binds the LDL receptor and targets it for degradation. We have found that a construct of proPCSK9 where the C-terminal domain has been truncated has sufficient stability to be expressed and purified from Escherichia coli for the in vitro study of autoprocessing. Using automated Western analysis, we demonstrate that autoprocessing exhibits the anticipated first-order kinetics. A high-throughput time-resolved fluorescence resonance energy transfer assay for autocleavage has been developed using a PCSK9 monoclonal antibody that is sensitive to the conformational changes that occur upon maturation of the proprotein. Kinetic theory has been developed that describes the behavior of both reversible and irreversible inhibitors of autocleavage. The analysis of an irreversible lactone inhibitor validates the expected relationship between potency and the reaction end point. An orthogonal liquid chromatography–mass spectrometry assay has also been implemented for the confirmation of hits from the antibody-based assays.

scholarly journals Protective Effect of Pitao (Pitavia punctata (R. & P.) Molina) Polyphenols against the Red Blood Cells Lipoperoxidation and the In Vitro LDL Oxidation

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Ricardo I. Castro ◽  
Oscar Forero-Doria ◽  
Luis Soto-Cerda ◽  
A. Peña-Neira ◽  
Luis Guzmán
Keyword(s):  
Oxidative Stress ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Hypochlorous Acid ◽  
Low Density Lipoprotein ◽  
Membrane Integrity ◽  
Density Lipoprotein ◽  
Ldl Oxidation ◽  
Quercetin Derivatives

The oxidative stress is characterized by an imbalance between the oxidizing agents and antioxidants; meanwhile, the consumption of antioxidants has been considered as an important tool in the prevention of oxidative stress and its consequences. Pitavia punctata (R. & P.) Molina is an endemic arboreal species from the Chilean Coast Range, in which a large amount of flavonoids has been described. This work focused on characterizing and evaluating, in human erythrocytes, the antioxidant capacity and membrane protection of P. punctata extracts and the in vitro protection of the oxidation of the Low Density Lipoprotein (LDL). The phytochemical screening revealed the presence of Quercetin derivatives and flavonoids, such as (-)-Epicatechin, Kaempferol, and derivatives. The methanolic extract presented an important antioxidant activity, protecting the membrane integrity of the red blood cells against the oxidative damage caused by Hypochlorous acid and inhibiting the oxidation of the LDL lipoprotein.

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