scholarly journals Cholesterol Efflux Capacity of Apolipoprotein A-I Varies with the Extent of Differentiation and Foam Cell Formation of THP-1 Cells

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Kouji Yano ◽  
Ryunosuke Ohkawa ◽  
Megumi Sato ◽  
Akira Yoshimoto ◽  
Naoya Ichimura ◽  
...  
Keyword(s):  
Cholesterol Efflux ◽  
Foam Cell ◽  
Cell Formation ◽  
Density Lipoprotein ◽  
Foam Cell Formation ◽  
Capacity Measurement ◽  
Cholesterol Efflux Capacity ◽  
Apolipoprotein A ◽  
Significant Difference ◽  
Main Protein

Apolipoprotein A-I (apoA-I), the main protein component of high-density lipoprotein (HDL), has many protective functions against atherosclerosis, one of them being cholesterol efflux capacity. Although cholesterol efflux capacity measurement is suggested to be a key biomarker for evaluating the risk of development of atherosclerosis, the assay has not been optimized till date. This study aims at investigating the effect of different states of cells on the cholesterol efflux capacity. We also studied the effect of apoA-I modification by homocysteine, a risk factor for atherosclerosis, on cholesterol efflux capacity in different states of cells. The cholesterol efflux capacity of apoA-I was greatly influenced by the extent of differentiation of THP-1 cells and attenuated by excessive foam cell formation.N-Homocysteinylated apoA-I indicated a lower cholesterol efflux capacity than normal apoA-I in the optimized condition, whereas no significant difference was observed in the cholesterol efflux capacity between apoA-I in the excessive cell differentiation or foam cell formation states. These results suggest that cholesterol efflux capacity of apoA-I varies depending on the state of cells. Therefore, the cholesterol efflux assay should be performed using protocols optimized according to the objective of the experiment.

Abstract 43: Cholesterol Efflux Pathways Suppress Inflammasome Activation in Mice and Humans

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Marit Westerterp ◽  
Panagiotis Fotakis ◽  
Mireille Ouimet ◽  
Andrea E Bochem ◽  
Hanrui Zhang ◽  
...  
Keyword(s):  
Plasma Levels ◽  
Cholesterol Efflux ◽  
Foam Cell ◽  
Cell Formation ◽  
Density Lipoprotein ◽  
Foam Cell Formation ◽  
Inflammasome Activation ◽  
Loss Of Function ◽  
Caspase 1 ◽  
Macrophage Cholesterol Efflux

Plasma high-density-lipoprotein (HDL) has several anti-atherogenic properties, including its key role in functioning as acceptor for ATP-binding cassette A1 and G1 (ABCA1 and ABCG1) mediated cholesterol efflux. We have shown previously that macrophage Abca1/g1 deficiency accelerates atherosclerosis, by enhancing foam cell formation and inflammatory cytokine expression in atherosclerotic plaques. Macrophage cholesterol accumulation activates the inflammasome, leading to caspase-1 cleavage, required for IL-1β and IL-18 secretion. Several studies have suggested that inflammasome activation accelerates atherogenesis. We hypothesized that macrophage Abca1/g1 deficiency activates the inflammasome. In Ldlr -/- mice fed a Western type diet (WTD), macrophage Abca1/g1 deficiency increased IL-1β and IL-18 plasma levels (2-fold; P <0.001), and induced caspase-1 cleavage. Deficiency of the inflammasome components Nlrp3 or caspase-1 in macrophage Abca1/g1 knockouts reversed the increase in plasma IL-18 levels ( P <0.001), indicating these changes were inflammasome dependent. We found that macrophage Abca1/g1 deficiency induced caspase-1 cleavage in splenic CD115 + monocytes and CD11b + macrophages. While mitochondrial ROS production or lysosomal function were not affected, macrophage Abca1/g1 deficiency led to an increased splenic population of monocytes (2.5-fold; P <0.01). Monocytes secrete ATP, and as a result, ATP secretion from total splenic cells was increased (2.5-fold; P <0.01), likely contributing to inflammasome activation. Caspase-1 deficiency decreased atherosclerosis in macrophage Abca1/g1 deficient Ldlr -/- mice fed WTD for 8 weeks (225822 vs 138606 μm 2 ; P <0.05). Of therapeutic interest, one injection of reconstituted HDL (100 mg/kg) in macrophage Abca1/g1 knockouts decreased plasma IL-18 levels ( P <0.05). Tangier disease patients, with a homozygous loss-of-function for ABCA1, showed increased IL-1β and IL-18 plasma levels (3-fold; P <0.001), suggesting that cholesterol efflux pathways also suppress inflammasome activation in humans. These findings suggest that macrophage cholesterol efflux pathways suppress inflammasome activation, possibly contributing to the anti-atherogenic effects of HDL treatment.

N-homocysteinylation of apolipoprotein A-I impairs the protein’s antioxidant ability but not its cholesterol efflux capacity

2014 ◽  
Vol 395 (6) ◽  
pp. 641-648 ◽  
Author(s):  
Akari Miyazaki ◽  
Nozomi Sagae ◽  
Yoko Usami ◽  
Megumi Sato ◽  
Takahiro Kameda ◽  
...  
Keyword(s):  
Cholesterol Efflux ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Lipid Binding ◽  
Binding Activity ◽  
Antioxidant Ability ◽  
Wild Type ◽  
Cholesterol Efflux Capacity ◽  
Apolipoprotein A ◽  
Significant Difference

Abstract A high homocysteine (Hcy) level is a risk factor for atherosclerosis. Hcy can be added to proteins through a process known as N-homocysteinylation. This is thought to be a potential cause of atherosclerosis induction. We previously reported that N-homocysteinylated apolipoprotein A-I (N-Hcy-apoA-I) was identified in normal human plasma. In this study, the effect of N-homocysteinylation on the functions of apoA-I was examined. A kinetic study using dimyristoyl phosphatidylcholine (DMPC) liposomes indicated that N-Hcy-apoA-I showed increased lipid-binding activity compared to wild-type apoA-I. Two reconstituted high-density lipoprotein (rHDL) particles of different sizes (approximately 8.2 nm and 7.6 nm in diameter) were produced by mixing apoA-I and 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC). However, an increased ratio of large to small particles was found in rHDL prepared with N-Hcy-apoA-I. The normal apoA-I antioxidant ability, estimated by the suppression of conjugated diene formation in low-density lipoprotein (LDL) induced by copper sulfate oxidation, was considerably impaired when using N-Hcy-apoA-I. Although N-Hcy-apoA-I functioned as an oxidant, no significant difference was observed in the cholesterol efflux capacity from THP-1 macrophages between wild-type apoA-I and N-Hcy-apoA-I. These results suggest that N-Hcy-apoA-I might be proatherogenic due to its oxidative behavior but not an attenuation of cholesterol efflux capacity.

scholarly journals ‘Blow my mind(in)’ – mindin neutralization for the prevention of atherosclerosis?

2018 ◽  
Vol 132 (14) ◽  
pp. 1509-1512
Author(s):  
Neil MacRitchie ◽  
Pasquale Maffia
Keyword(s):  
Vessel Wall ◽  
Cholesterol Efflux ◽  
Matrix Protein ◽  
Foam Cell ◽  
Cell Formation ◽  
Density Lipoprotein ◽  
Extracellular Matrix Protein ◽  
Foam Cell Formation ◽  
Protective Effects ◽  
Inflammatory Microenvironment

The hallmark features of atherosclerosis include accumulation of low-density lipoprotein (LDL) carrying cholesterol in the vessel wall, formation of lipid-laden foam cells, and the creation of a pro-inflammatory microenvironment. To date, no effective treatments are clinically available for increasing cholesterol efflux from vascular macrophages and inducing reverse cholesterol transport (RCT). In an article published recently in Clinical Science (vol 132, issue 6, 1199-1213), Zhang and colleagues identified the extracellular matrix protein mindin/spondin 2 as a positive regulator of atherosclerosis. Genetic knockout of mindin in apolipoprotein-E (apoE)−/− mice attenuated atherosclerosis, foam cell formation, and inflammation within the vessel wall. Conversely, selective overexpression of mindin in macrophages in apoE−/− mice was sufficient to promote the greater severity of atherosclerosis. Interestingly, foam cell formation was closely associated with the expression of cholesterol transporters (ABCA1 and ACBG1) that facilitate cholesterol efflux. Liver X receptor (LXR)-β is a key modulator of cholesterol transporter expression and formed direct interactions with mindin. Furthermore, the protective effects of mindin deficiency on foam cell formation were blocked by inhibition of LXR-β. This article highlights a novel role of mindin in modulating foam cell formation and atherosclerosis development in mice through direct regulation of LXR-β. Thus far, direct targetting of LXR-β via pharmacological agonists has proven to be problematic due to the lack of subtype selective inhibitors and associated adverse effects. Indirect targetting of LXR-β, therefore, via mindin inhibition offers a new therapeutic strategy for increasing LXR-β induced cholesterol efflux, reducing foam cell formation, and preventing or treating atherosclerosis.

scholarly journals Naoxintong Retards Atherosclerosis by Inhibiting Foam Cell Formation Through Activating Pparα Pathway

2019 ◽  
Vol 18 (10) ◽  
pp. 698-710 ◽  
Author(s):  
Zeng Wang ◽  
Huairui Shi ◽  
Huan Zhao ◽  
Zhen Dong ◽  
Buchang Zhao ◽  
...  
Keyword(s):  
Cholesterol Efflux ◽  
Foam Cell ◽  
Low Density Lipoprotein ◽  
Cell Formation ◽  
Density Lipoprotein ◽  
Foam Cell Formation ◽  
Oxidized Low Density Lipoprotein ◽  
Beneficial Effects ◽  
Cell Accumulation ◽  
Ldl Uptake

Background: We recently reported that Naoxintong (NXT), a China Food and Drug Administration (FDA)-approved cardiac medicine, could reduce the plaque size, but the underlying mechanism remains elusive now. Objective: In this study, we investigated the effects of NXT on foam cell accumulation both in vivo and in vitro and explored related mechanisms. Method: THP-1 cells and bone marrow-derived macrophages were incubated with oxidized low-density lipoprotein (ox-LDL) with/without Naoxintong. ApoE-/- mice fed an atherogenic diet were administered to receive NXT for eight weeks. Macrophage-derived foam cell formation in plaques was measured by immunohistochemical staining. Expression of proteins was evaluated by Western blot. Lentivirus was used to knockdown PPARα in THP-1 cells. Results: After NXT treatment, foam cell accumulation was significantly reduced in atherosclerotic plaques. Further investigation revealed that oxidized low-density lipoprotein (ox-LDL) uptake was significantly decreased and expression of scavenger receptor class A (SR-A) and class B (SR-B and CD36) was significantly downregulated post-NXT treatment. On the other hand, NXT increased cholesterol efflux and upregulated ATP-binding cassette (ABC) transporters (ABCA-1 and ABCG-1) in macrophages. Above beneficial effects of NXT were partly abolished after lentiviral knockdown of PPARα. Conclusion: Our findings suggest that NXT could retard atherosclerosis by inhibiting foam cell formation through reducing ox-LDL uptake and enhancing cholesterol efflux and above beneficial effects are partly mediated through PPARα pathway.

ClC-3: A Novel Promising Therapeutic Target for Atherosclerosis

2021 ◽  
pp. 107424842110236
Author(s):  
Dun Niu ◽  
Lanfang Li ◽  
Zhizhong Xie
Keyword(s):  
Therapeutic Target ◽  
Chloride Channels ◽  
Foam Cell ◽  
Low Density Lipoprotein ◽  
Cell Formation ◽  
Density Lipoprotein ◽  
Molecular Structures ◽  
Foam Cell Formation ◽  
Endothelium Dysfunction ◽  
Atherosclerotic Process

Chloride channel 3 (ClC-3), a Cl−/H+ antiporter, has been well established as a member of volume-regulated chloride channels (VRCCs). ClC-3 may be a crucial mediator for activating inflammation-associated signaling pathways by regulating protein phosphorylation. A growing number of studies have indicated that ClC-3 overexpression plays a crucial role in mediating increased plasma low-density lipoprotein levels, vascular endothelium dysfunction, pro-inflammatory activation of macrophages, hyper-proliferation and hyper-migration of vascular smooth muscle cells (VSMCs), as well as oxidative stress and foam cell formation, which are the main factors responsible for atherosclerotic plaque formation in the arterial wall. In the present review, we summarize the molecular structures and classical functions of ClC-3. We further discuss its emerging role in the atherosclerotic process. In conclusion, we explore the potential role of ClC-3 as a therapeutic target for atherosclerosis.

scholarly journals Protective Effect of Lusianthridin on Hemin-Induced Low-Density Lipoprotein Oxidation

2021 ◽  
Vol 14 (6) ◽  
pp. 567
Author(s):  
Su Wutyi Thant ◽  
Noppawan Phumala Morales ◽  
Visarut Buranasudja ◽  
Boonchoo Sritularak ◽  
Rataya Luechapudiporn
Keyword(s):  
Foam Cell ◽  
Low Density Lipoprotein ◽  
Cell Formation ◽  
Density Lipoprotein ◽  
Foam Cell Formation ◽  
Raw 264.7 ◽  
Low Density ◽  
Lipoprotein Oxidation ◽  
Raw 264.7 Macrophage Cells ◽  
Low Density Lipoprotein Oxidation

Oxidation of low-density lipoprotein (LDL) plays a crucial role in the pathogenesis of atherosclerosis. Hemin (iron (III)-protoporphyrin IX) is a degradation product of hemoglobin that can be found in thalassemia patients. Hemin is a strong oxidant that can cause LDL oxidation and contributes to atherosclerosis in thalassemia patients. Lusianthridin from Dendrobium venustrum is a phenolic compound that possesses antioxidant activity. Hence, lusianthridin could be a promising compound to be used against hemin-induced oxidative stress. The major goal of this study is to evaluate the protective effect of lusianthridin on hemin-induced low-density lipoprotein oxidation (he-oxLDL). Here, various concentrations of lusianthridin (0.25, 0.5, 1, and 2 µM) were preincubated with LDL for 30 min, then 5 µM of hemin was added to initiate the oxidation, and oxidative parameters were measured at various times of incubation (0, 1, 3, 6, 12, 24 h). Lipid peroxidation of LDL was measured by thiobarbituric reactive substance (TBARs) assay and relative electrophoretic mobility (REM). The lipid composition of LDL was analyzed by using reverse-phase HPLC. Foam cell formation with he-oxLDL in RAW 264.7 macrophage cells was detected by Oil Red O staining. The results indicated that lusianthridin could inhibit TBARs formation, decrease REM, decrease oxidized lipid products, as well as preserve the level of cholesteryl arachidonate and cholesteryl linoleate. Moreover, He-oxLDL incubated with lusianthridin for 24 h can reduce the foam cell formation in RAW 264.7 macrophage cells. Taken together, lusianthridin could be a potential agent to be used to prevent atherosclerosis in thalassemia patients.

scholarly journals Structure and Dynamics of Oxidized Lipoproteins In Vivo: Roles of High-Density Lipoprotein

Biomedicines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 655
Author(s):  
Hiroyuki Itabe ◽  
Naoko Sawada ◽  
Tomohiko Makiyama ◽  
Takashi Obama
Keyword(s):  
Cardiovascular Diseases ◽  
High Density Lipoprotein ◽  
Foam Cell ◽  
Cell Formation ◽  
Density Lipoprotein ◽  
High Density ◽  
Oxidative Modification ◽  
Foam Cell Formation ◽  
Oxidized Lipoproteins

Oxidative modification of lipoproteins is implicated in the occurrence and development of atherosclerotic lesions. Earlier studies have elucidated on the mechanisms of foam cell formation and lipid accumulation in these lesions, which is mediated by scavenger receptor-mediated endocytosis of oxidized low-density lipoprotein (oxLDL). Mounting clinical evidence has supported the involvement of oxLDL in cardiovascular diseases. High-density lipoprotein (HDL) is known as anti-atherogenic; however, recent studies have shown circulating oxidized HDL (oxHDL) is related to cardiovascular diseases. A modified structure of oxLDL, which was increased in the plasma of patients with acute myocardial infarction, was characterized. It had two unique features: (1) a fraction of oxLDL accompanied oxHDL, and (2) apoA1 was heavily modified, while modification of apoB, and the accumulation of oxidized phosphatidylcholine (oxPC) and lysophosphatidylcholine (lysoPC) was less pronounced. When LDL and HDL were present at the same time, oxidized lipoproteins actively interacted with each other, and oxPC and lysoPC were transferred to another lipoprotein particle and enzymatically metabolized rapidly. This brief review provides a novel view on the dynamics of oxLDL and oxHDL in circulation.

Abstract 3691: Deletion of Suppressor Of Cytokine Signaling-1 in a Murine Model of Atherosclerosis Results in a Lethal Systemic Inflammation

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Christina Grothusen ◽  
Harald Schuett ◽  
Stefan Lumpe ◽  
Andre Bleich ◽  
Silke Glage ◽  
...  
Keyword(s):  
Foam Cell ◽  
Low Density Lipoprotein ◽  
Cell Formation ◽  
Density Lipoprotein ◽  
Foam Cell Formation ◽  
Cytokine Signaling ◽  
Suppressor Of Cytokine Signaling ◽  
The Impact

Introduction: Atherosclerosis is a chronic inflammatory disease of the cardiovascular system which may result in myocardial infarction and sudden cardiac death. While the role of pro-inflammatory signaling pathways in atherogenesis has been well characterized, the impact of their negative regulators, e.g. suppressor of cytokine signaling (SOCS)-1 remains to be elucidated. Deficiency of SOCS-1 leads to death 3 weeks post-partum due to an overwhelming inflammation caused by an uncontrolled signalling of interferon-gamma (IFNγ). This phenotype can be rescued by generating recombination activating gene (rag)-2, SOCS-1 double knock out (KO) mice lacking mature lymphocytes, the major source of IFNγ. Since the role of SOCS-1 during atherogenesis is unknown, we investigated the impact of a systemic SOCS-1 deficiency in the low-density lipoprotein receptor (ldlr) KO model of atherosclerosis. Material and Methods: socs-1 −/− /rag-2 −/− deficient mice were crossed with ldlr-KO animals. Mice were kept under sterile conditions on a normal chow diet. For in-vitro analyses, murine socs-1 −/− macrophages were stimulated with native low density lipoprotein (nLDL) or oxidized (ox)LDL. SOCS-1 expression was determined by quantitative PCR and western blot. Foam cell formation was determined by Oil red O staining. Results: socs-1 −/− /rag-2 −/− /ldlr −/− mice were born according to mendelian law. Tripel-KO mice showed a reduced weight and size, were more sensitive to bacterial infections and died within 120 days (N=17). Histological analyses revealed a systemic, necrotic, inflammation in Tripel-KO mice. All other genotypes developed no phenotype. In-vitro observations revealed that SOCS-1 mRNA and protein is upregulated in response to stimulation with oxLDL but not with nLDL. Foam cell formation of socs-1 −/− macrophages was increased compared to controls. Conclusion: SOCS-1 seemingly controls critical steps of atherogenesis by modulating foam cell formation in response to stimulation with oxLDL. SOCS-1 deficiency in the ldlr-KO mouse leads to a lethal inflammation. These observations suggest a critical role for SOCS-1 in the regulation of early inflammatory responses in atherogenesis.

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