scholarly journals Accumulation of LDL/ox-LDL in the necrotic region participates in osteonecrosis of the femoral head: a pathological and in vitro study

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Xin-Yuan Wang ◽  
Tian-Le Ma ◽  
Kang-Ning Chen ◽  
Zhi-Ying Pang ◽  
Hao Wang ◽  
...  
Keyword(s):  
Femoral Head ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
In Vitro Study ◽  
Long Bone ◽  
Blood Levels ◽  
Necrotic Region

Abstract Background Osteonecrosis of the femoral head (ONFH) is a common but intractable disease that appears to involve lipid metabolic disorders. Although numerous studies have demonstrated that high blood levels of low-density lipoprotein (LDL) are closely associated with ONFH, there is limited evidence to explain the pathological role of LDL. Pathological and in vitro studies were performed to investigate the role of disordered metabolism of LDL and oxidized LDL (ox-LDL) in the femoral head in the pathology of ONFH. Methods Nineteen femoral head specimens from patients with ONFH were obtained for immunohistochemistry analysis. Murine long-bone osteocyte Y4 cells were used to study the effects of LDL/ox-LDL on cell viability, apoptosis, and metabolism process of LDL/ox-LDL in osteocytes in normoxic and hypoxic environments. Results In the pathological specimens, marked accumulation of LDL/ox-LDL was observed in osteocytes/lacunae of necrotic regions compared with healthy regions. In vitro studies showed that ox-LDL, rather than LDL, reduced the viability and enhanced apoptosis of osteocytes. Pathological sections indicated that the accumulation of ox-LDL was significantly associated with impaired blood supply. Exposure to a hypoxic environment appeared to be a key factor leading to LDL/ox-LDL accumulation by enhancing internalisation and oxidation of LDL in osteocytes. Conclusions The accumulation of LDL/ox-LDL in the necrotic region may contribute to the pathology of ONFH. These findings could provide new insights into the prevention and treatment of ONFH.

scholarly journals Oxidized LDL Disrupts Metabolism and Inhibits Macrophage Survival by Activating a miR-9/Drp1/Mitochondrial Fission Signaling Pathway

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Ting Xin ◽  
Chengzhi Lu ◽  
Jing Zhang ◽  
Jiaxin Wen ◽  
Shuangbin Yan ◽  
...  
Keyword(s):  
Inflammatory Responses ◽  
Cholesterol Metabolism ◽  
Oxidized Ldl ◽  
Mitochondrial Fission ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
The Novel ◽  
Macrophage Viability

Mitochondrial dysfunction is associated with macrophage damage, but the role of mitochondrial fission in macrophage cholesterol metabolism is not fully understood. In this study, we explored the influences of miR-9 and mitochondrial fission on macrophage viability and cholesterol metabolism. Macrophages were incubated with oxidized low-density lipoprotein (ox-LDL) in vitro, after which mitochondrial fission, cell viability, and cholesterol metabolism were examined using qPCR, ELISAs, and immunofluorescence. ox-LDL treatment significantly increased Drp1-associated mitochondrial fission. Transfection of Drp1 siRNA significantly reduced cell death, attenuated oxidative stress, and inhibited inflammatory responses in ox-LDL-treated macrophages. Interestingly, inhibition of Drp1-related mitochondrial fission also improved cholesterol metabolism by balancing the transcription of cholesterol influx/efflux enzymes. We also found that miR-9 was downregulated in ox-LDL-treated macrophages, and administration of a miR-9 mimic decreased Drp1 transcription and mitochondrial fission, as well as its effects. These results indicate that signaling via the novel miR-9/Drp1/mitochondrial fission axis is a key determinant of macrophage viability and cholesterol metabolism.

scholarly journals Development of Capture Assays for Different Modifications of Human Low-Density Lipoprotein

2005 ◽  
Vol 12 (1) ◽  
pp. 68-75 ◽  
Author(s):  
Gabriel Virella ◽  
M. Brooks Derrick ◽  
Virginia Pate ◽  
Charlyne Chassereau ◽  
Suzanne R. Thorpe ◽  
...  
Keyword(s):  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Gas Chromatography Mass Spectrometry ◽  
Low Density ◽  
Modified Ldl ◽  
Capture Assay ◽  
Carboxymethyl Lysine

ABSTRACT Antibodies to malondialdehyde (MDA)-modified low-density lipoprotein (LDL), copper-oxidized LDL (oxLDL), N ε(carboxymethyl) lysine (CML)-modified LDL, and advanced glycosylation end product (AGE)-modified LDL were obtained by immunization of rabbits with in vitro-modified human LDL preparations. After absorption of apolipoprotein B (ApoB) antibodies, we obtained antibodies specific for each modified lipoprotein with unique patterns of reactivity. MDA-LDL antibodies reacted strongly with MDA-LDL and also with oxLDL. CML-LDL antibodies reacted strongly with CML-LDL and also AGE-LDL. oxLDL antibodies reacted with oxLDL but not with MDA-LDL, and AGE-LDL antibodies reacted with AGE-LDL but not with CML-LDL. Capture assays were set with each antiserum, and we tested their ability to capture ApoB-containing lipoproteins isolated from precipitated immune complexes (IC) and from the supernatants remaining after IC precipitation (free lipoproteins). All antibodies captured lipoproteins contained in IC more effectively than free lipoproteins. Analysis of lipoproteins in IC by gas chromatography-mass spectrometry showed that they contained MDA-LDL and CML-LDL in significantly higher concentrations than free lipoproteins. A significant correlation (r = 0.706, P < 0.019) was obtained between the MDA concentrations determined by chemical analysis and by the capture assay of lipoproteins present in IC. In conclusion, we have developed capture assays for different LDL modifications in human ApoB/E lipoprotein-rich fractions isolated from precipitated IC. This approach obviates the interference of IC in previously reported modified LDL assays and allows determination of the degree of modification of LDL with greater accuracy.

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.

scholarly journals Oxidized LDL but not angiotensin II induces the interaction between LOX-1 and AT1 receptors

2020 ◽  
Author(s):  
Li Lin ◽  
Ning Zhou ◽  
Le Kang ◽  
Qi Wang ◽  
Jian Wu ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Direct Interaction ◽  
Cardiomyocyte Hypertrophy ◽  
Oxidized Low Density Lipoprotein ◽  
Protein Activation

Oxidized low-density lipoprotein (Ox-LDL) can induce cardiac hypertrophy, but the mechanism is still unclear. Here we elucidate the role of angiotensin II (AngII) receptor (AT1-R) in Ox-LDL-induced cardiomycyte hypertrophy. Inhibition of Ox-LDL receptor LOX-1 and AT1-R rather than AngII abolished Ox-LDL-induced hypertrophic responses. Similar results were obtained from the heart of mice lacking endogenous Ang II and their cardiomyocytes. Ox-LDL but not AngII induced binding of LOX-1 to AT1-R, and the inhibition of LOX-1 or AT1-R rather than AngII abolished the association of these two receptors. Ox-LDL-induced ERKs phosphorylation in LOX-1 and AT1-R-overexpression cells and the binding of both receptors were suppressed by the mutants of LOX-1 (Lys266Ala/Lys267Ala) or AT1-R (Glu257Ala), however, the AT1-R mutant lacking Gq protein-coupling ability only abolished the ERKs phosphorylation. The phosphorylation of ERKs induced by Ox-LDL in LOX-1 and AT1-R-overexpression cells was abrogated by Gq protein inhibitor but not by Jak2, Rac1 and RhoA inhibitors. Therefore, the direct interaction between LOX-1 and AT1-R and the downstream Gq protein activation are important mechanisms for Ox-LDL- but not AngII-induced cardiomyocyte hypertrophy

scholarly journals Constitutive and stimulated macropinocytosis in macrophages: roles in immunity and in the pathogenesis of atherosclerosis

2018 ◽  
Vol 374 (1765) ◽  
pp. 20180147 ◽  
Author(s):  
Sasha A. Doodnauth ◽  
Sergio Grinstein ◽  
Michelle E. Maxson
Keyword(s):  
Foam Cell ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Immune Surveillance ◽  
Density Lipoprotein ◽  
Unique Type ◽  
Functional Roles ◽  
Fluid Uptake ◽  
Molecular Patterns

Macrophages respond to several stimuli by forming florid membrane ruffles that lead to fluid uptake by macropinocytosis. This type of induced macropinocytosis, executed by a variety of non-malignant and malignant cells, is initiated by transmembrane receptors and is involved in nutrient acquisition and mTOR signalling. However, macrophages also perform a unique type of constitutive ruffling and macropinocytosis that is dependent on the presence of extracellular calcium. Calcium-sensing receptors are responsible for this activity. This distinct form of macropinocytosis enables macrophages to continuously sample their microenvironment for antigenic molecules and for pathogen- and danger-associated molecular patterns, as part of their immune surveillance functions. Interestingly, even within the monocyte lineage, there are differences in macropinocytic ability that reflect the polarized functional roles of distinct macrophage subsets. This review discusses the shared and distinct features of both induced and constitutive macropinocytosis displayed by the macrophage lineage and their roles in physiology, immunity and pathophysiology. In particular, we analyse the role of macropinocytosis in the uptake of modified low-density lipoprotein (LDL) and its contribution to foam cell and atherosclerotic plaque formation. We propose a combined role of scavenger receptors and constitutive macropinocytosis in oxidized LDL uptake, a process we have termed ‘receptor-assisted macropinocytosis'. This article is part of the Theo Murphy meeting issue ‘Macropinocytosis’.

scholarly journals Role of Lectin-Like Oxidized Low Density Lipoprotein-1 in Fetoplacental Vascular Dysfunction in Preeclampsia

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Felipe A. Zuniga ◽  
Valeska Ormazabal ◽  
Nicolas Gutierrez ◽  
Valeria Aguilera ◽  
Claudia Radojkovic ◽  
...  
Keyword(s):  
Endothelial Dysfunction ◽  
Vascular Dysfunction ◽  
Pathological Condition ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Fetal Loss ◽  
Density Lipoprotein ◽  
Placental Tissue

The bioavailability of nitric oxide (NO) represents a key marker in vascular health. A decrease in NO induces a pathological condition denominated endothelial dysfunction, syndrome observed in different pathologies, such as obesity, diabetes, kidney disease, cardiovascular disease, and preeclampsia (PE). PE is one of the major risks for maternal death and fetal loss. Recent studies suggest that the placenta of pregnant women with PE express high levels of lectin-like oxidized LDL receptor-1 (LOX-1), which induces endothelial dysfunction by increasing reactive oxygen species (ROS) and decreasing intracellular NO. Besides LOX-1 activation induces changes in migration and apoptosis of syncytiotrophoblast cells. However, the role of this receptor in placental tissue is still unknown. In this review we will describes the physiological roles of LOX-1 in normal placenta development and the potential involvement of this receptor in the pathophysiology of PE.

IN VITRO STUDY OF A NOVEL LOW-DENSITY LIPOPROTEIN ADSORBENT

2002 ◽  
Vol 30 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Ning-Ning Cao ◽  
Yao-Ting Yu ◽  
Man-Yan Wang ◽  
Chang-Zhi Chen
Keyword(s):  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
In Vitro Study ◽  
Vitro Study ◽  
Low Density

Vascular responses and ion exchange in diabetes: Authors' reply

1992 ◽  
Vol 82 (3) ◽  
pp. 339-339
Author(s):  
J. M. Ritter ◽  
G. C. Viberti
Keyword(s):  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Large Body ◽  
Plasma Lipid ◽  
Density Lipoprotein ◽  
High Plasma ◽  
Diabetic Patients ◽  
Vascular Sensitivity

1. Na+/Li+ countertransport is not a gold standard, or indeed any other kind of standard. It is a measure of the activity of one particular cation exchanger. 2. There is a large body of literature regarding the effects of oxidized low-density lipoprotein (LDL) in experimental animals and in vitro. Whether abnormal oxidized LDL or one of many other possible mechanisms underlies the inverse relationship that we observed between vascular sensitivity in vivo to nitroprusside or carbachol with erythrocyte Na+/Li+ countertransport in diabetic patients remains to be seen. 3. We caution against post hoc subgroup analysis (smokers versus non-smokers, low versus high plasma lipid levels, etc.) in studies of this size.

Gemfibrozil metabolite inhibits in vitro low-density lipoprotein (LDL) oxidation and diminishes cytotoxicity induced by oxidized LDL

Metabolism ◽  
2000 ◽  
Vol 49 (4) ◽  
pp. 479-485 ◽  
Author(s):  
Mitsunobu Kawamura ◽  
Shigeru Miyazaki ◽  
Tamio Teramoto ◽  
Keiko Ashidate ◽  
Hisako Thoda ◽  
...  
Keyword(s):  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Ldl Oxidation ◽  
Low Density

Low density lipoprotein increases amyloid precursor protein processing to amyloidogenic pathway in differentiated SH-SY5Y cells

Biologia ◽  
2017 ◽  
Vol 72 (2) ◽  
Author(s):  
Panit Yamchuen ◽  
Rattima Jeenapongsa ◽  
Sutisa Nudmamud-Thanoi ◽  
Nanteetip Limpeanchob
Keyword(s):  
Amyloid Precursor Protein ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Neuroblastoma Cells ◽  
Density Lipoprotein ◽  
Precursor Protein ◽  
Amyloid Precursor Protein Processing ◽  
Low Density ◽  
App Processing

AbstractHypercholesterolemia has been considered as a risk factor for Alzheimer’s disease (AD). In addition to low density lipoprotein (LDL), oxidized LDL plays some roles in AD pathology. Neurodegenerative effect of oxidized LDL was supported by the increased oxidative stress in neurons. To further investigate the role of oxidized LDL, the present study aimed to test its effect on amyloid precursor protein (APP) processing. The release of soluble APP (sAPP) was evaluated in differentiated SH-SY5Y neuroblastoma cells exposed to native (non-oxidized) or oxidized human LDL including mildly and fully oxidized LDL (mox- and fox-LDL). Non-amyloidogenic and amyloidogenic pathways were investigated using specific antibody against sAPP

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