scholarly journals Actin Polymerization in Macrophages in Response to Oxidized LDL and Apoptotic Cells: Role of 12/15-Lipoxygenase and Phosphoinositide 3-Kinase

2003 ◽  
Vol 14 (10) ◽  
pp. 4196-4206 ◽  
Author(s):  
Yury I. Miller ◽  
Dorothy S. Worrall ◽  
Colin D. Funk ◽  
James R. Feramisco ◽  
Joseph L. Witztum
Keyword(s):  
Cell Membrane ◽  
Actin Polymerization ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Specific Inhibitor ◽  
Density Lipoprotein ◽  
Oxidation Products ◽  
Apoptotic Cells ◽  
Lipid Oxidation Products ◽  
Phosphoinositide 3 Kinase

Formation of filamentous F-actin drives many cellular processes, including phagocytosis and cell spreading. We have recently reported that mouse macrophage 12/15-lipoxygenase (12/15-LO) activity promotes F-actin formation in filopodia during phagocytosis of apoptotic cells. Oxidized low-density lipoprotein (OxLDL) also stimulates robust F-actin formation and spreading of macrophages. However, unlike apoptotic cells, OxLDL did not cause specific translocation of 12/15-LO to the cell membrane, neither in macrophages nor in GFP-15LO–transfected COS-7 cells. Moreover, inhibition of 12/15-LO activity in macrophages by a specific inhibitor or by 12/15-LO gene disruption did not affect OxLDL-induced actin polymerization. Among LDL modifications modeling OxLDL, LDL modified by incubation with 15LO-overexpressing fibroblasts was as active in eliciting F-actin response as was OxLDL. This LDL modification is well known to produce minimally modified LDL (mmLDL), which is bioactive and carries lipid oxidation products similar to those produced by 12/15-LO catalysis. MmLDL activated phosphoinositide 3-kinase (PI3K), and PI3K inhibitors abolished mmLDL-induced macrophage spreading. We hypothesize that OxLDL and mmLDL may contribute oxidized lipids to the macrophage cell membrane and thereby mimic intracellular 12/15-LO activity, which leads to uncontrolled actin polymerization and dramatic cytoskeletal changes in macrophages.

Differential PDGF secretion by graft and aortic SMC in response to oxidized LDL

2002 ◽  
Vol 283 (2) ◽  
pp. H725-H732 ◽  
Author(s):  
Afaf Absood ◽  
Akira Furutani ◽  
Tsutomu Kawamura ◽  
Linda M. Graham
Keyword(s):  
Oxidative Stress ◽  
Lipid Oxidation ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Vascular Grafts ◽  
Density Lipoprotein ◽  
Oxidation Products ◽  
Enzyme Linked Immunosorbent Assay ◽  
Oxidized Low Density Lipoprotein ◽  
Lipid Oxidation Products

Smooth muscle cells (SMC) from prosthetic vascular grafts constitutively secrete higher levels of platelet-derived growth factor-AA (PDGF-AA) than aortic SMC. Lipid oxidation products accumulate in grafts and may stimulate PDGF production. The effect of oxidized low-density lipoprotein (oxLDL) on PDGF-AA secretion by aortic and graft SMC was compared. SMC isolated from canine thoracic aorta or Dacron thoracoabdominal grafts ( n = 10) were incubated with native LDL or oxLDL (0–400 μg/ml) for 72 h. PDGF-AA in the conditioned medium was measured with enzyme-linked immunosorbent assay. OxLDL increased PDGF-AA production by graft SMC from 78 ± 2 to 256 ± 16 pg PDGF/μg DNA and aortic SMC from 21 ± 1 to 40 ± 2 pg PDGF/μg DNA. Native LDL had no effect. N-acetylcysteine inhibited oxLDL-induced PDGF increase. Both superoxide and H2O2 stimulated PDGF secretion by graft SMC had little effect on aortic SMC. Our results suggest that PDGF production by graft (synthetic) SMC is more sensitive to stimulation by oxidative stress than aortic (contractile) SMC. Lipid oxidation products that accumulate in prosthetic vascular grafts can cause an oxidative stress, which stimulates PDGF production by graft SMC. PDGF can induce migration of aortic SMC onto the graft, contributing to the development of intimal hyperplasia.

scholarly journals Phosphoinositide 3-kinase inhibits megalin-mediated transcytosis of thyroglobulin across thyroid epithelial cells at a post-sorting level

2001 ◽  
pp. 477-483 ◽  
Author(s):  
M Marino ◽  
L Chiovato ◽  
S Lisi ◽  
A Pinchera ◽  
RT McCluskey
Keyword(s):  
Low Density Lipoprotein ◽  
Specific Inhibitor ◽  
Density Lipoprotein ◽  
Inhibitory Effect ◽  
Thyroid Cells ◽  
Microbial Product ◽  
Phosphoinositide 3 Kinase ◽  
Rat Thyroid ◽  
Upper Chamber

BACKGROUND: Phosphoinositide 3-kinase (PI3-K) is implicated in various cellular processes involving signaling, including intracellular trafficking. PI3-K has been shown to play a part in both receptor- and non-receptor-mediated transcytosis across cultured kidney cells and undifferentiated thyroid cells. OBJECTIVE: To investigate the role of PI3-K in transcytosis of thyroglobulin (Tg) across differentiated cultured Fisher rat thyroid cells (FRTL-5 cells) - a process known to be mediated by megalin, a member of the low-density lipoprotein receptor family. DESIGN: We studied the effect of the microbial product wortmannin, a specific inhibitor of PI3-K, on transcytosis of Tg across FRTL-5 cells. METHODS: Transcytosis experiments were performed using FRTL-5 cells cultured as tight layers on filters in the upper chamber of dual chambered devices, with megalin expression exclusively on the upper cell surface. Tg was added to the upper chamber and cells were incubated at 37 degrees C. Transcytosed Tg was measured in fluids collected from the lower chamber. To study the role of PI3-K, cells were pre-incubated with wortmannin. RESULTS: Pre-incubation of FRTL-5 cells with wortmannin did not affect Tg binding and uptake, but resulted in a considerable increase in Tg transcytosis (by 40-75%, depending on the concentration of wortmannin), suggesting that PI3-K exerts an inhibitory effect on Tg transcytosis. In experiments in which a monoclonal antibody against megalin was used to reduce Tg transcytosis, pre-incubation with wortmannin did not increase Tg transcytosis from its reduced levels, indicating that PI3-K is involved in the megalin-mediated pathway. Wortmannin did not affect the extent of release of tri-iodothyronine from exogenously added Tg by FRTL-5 cells, which was used as a measure of Tg degradation in the lysosomal pathway, indicating that the effect of PI3-K on transcytosis occurs after diversion of Tg from the lysosomal pathway. CONCLUSIONS: PI3-K exerts an inhibitory role on megalin-mediated Tg transcytosis across cultured thyroid cells. PI3-K action takes place at a post-sorting level, after Tg bypassing of the lysosomal pathway.

scholarly journals Apoptotic Cells with Oxidation-specific Epitopes Are Immunogenic and Proinflammatory

2004 ◽  
Vol 200 (11) ◽  
pp. 1359-1370 ◽  
Author(s):  
Mi-Kyung Chang ◽  
Christoph J. Binder ◽  
Yury I. Miller ◽  
Ganesamoorthy Subbanagounder ◽  
Gregg J. Silverman ◽  
...  
Keyword(s):  
Apoptotic Cell ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Cell Interaction ◽  
Biologically Active ◽  
Apoptotic Cells ◽  
Proinflammatory Response ◽  
Local Inflammatory Response ◽  
Oxidatively Modified

Oxidation of low density lipoprotein (LDL) generates a variety of oxidatively modified lipids and lipid-protein adducts that are immunogenic and proinflammatory, which in turn contribute to atherogenesis. Cells undergoing apoptosis also display oxidized moieties on their surface membranes, as determined by binding of oxidation-specific monoclonal antibodies. In the present paper, we demonstrated by mass spectrometry that in comparison with viable cells, membranes of cells undergoing apoptosis contain increased levels of biologically active oxidized phospholipids (OxPLs). Indeed, immunization of mice with syngeneic apoptotic cells induced high autoantibody titers to various oxidation-specific epitopes of oxidized LDL, including OxPLs containing phosphorylcholine, whereas immunization with viable thymocytes, primary necrotic thymocytes, or phosphate-buffered saline did not. Reciprocally, these antisera specifically bound to apoptotic cells through the recognition of oxidation-specific epitopes. Moreover, splenocyte cultures from mice immunized with apoptotic cells spontaneously released significant levels of T helper cell (Th) 1 and Th2 cytokines, whereas splenocytes from controls yielded only low levels. Finally, we demonstrated that the OxPLs of apoptotic cells activated endothelial cells to induce monocyte adhesion, a proinflammatory response that was abrogated by an antibody specific to oxidized phosphatidylcholine. These results suggest that apoptotic cell death generates oxidatively modified moieties, which can induce autoimmune responses and a local inflammatory response by recruiting monocytes via monocyte–endothelial cell interaction.

A comparison of oxidized LDL-induced collagen secretion by graft and aortic SMCs: role of PDGF

2004 ◽  
Vol 287 (3) ◽  
pp. H1200-H1206 ◽  
Author(s):  
Afaf Absood ◽  
Akira Furutani ◽  
Tsutomu Kawamura ◽  
Linda M. Graham
Keyword(s):  
Lipid Oxidation ◽  
Type I Collagen ◽  
Oxidized Ldl ◽  
Vascular Grafts ◽  
Density Lipoprotein ◽  
Oxidation Products ◽  
Type I ◽  
Collagen Production ◽  
Collagen Secretion ◽  
Lipid Oxidation Products

Smooth muscle cells (SMCs) from prosthetic vascular grafts constitutively secrete higher levels of collagen than aortic SMCs. Lipid oxidation products accumulate in grafts, and we postulated that they stimulate SMC production of collagen. The effect of oxidized low-density lipoprotein (oxLDL) on type I collagen secretion by aortic and graft SMCs was compared. SMCs isolated from the canine thoracic aorta or Dacron thoracoabdominal grafts ( n = 10) were incubated with native LDL or oxLDL (0–400 μg cholesterol/ml) for 72 h. Type I collagen in the conditioned medium was measured by ELISA. OxLDL increased collagen production by graft SMCs from 4.1 ± 0.3 to 11.0 ± 0.4 ng/μg DNA and by aortic SMCs from 2.3 ± 0.1 to 3.5 ± 0.2 ng/μg DNA. Native LDL had little effect. LY-83583, a superoxide generator, stimulated a dramatic increase in collagen secretion by graft SMCs and a smaller but significant elevation by aortic SMCs. OxLDL has been shown to increase PDGF production by graft SMCs, and PDGF can stimulate collagen production. Anti-PDGF antibody inhibited the increase in collagen production by graft SMCs that was stimulated by oxLDL, implicating PDGF as one mechanism of oxLDL-induced collagen production. Lipid oxidation products that accumulate in prosthetic vascular grafts can cause an oxidative stress that stimulates PDGF production by graft SMCs that in turn stimulates collagen production, contributing to the progression of intimal hyperplasia.

scholarly journals Oxidative Modification of LDL by Various Physicochemical Techniques: Its Probable Role in Diabetes Coupled with CVDs

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Sultan Alouffi ◽  
Mohammad Faisal ◽  
Abdulrahman A. Alatar ◽  
Saheem Ahmad
Keyword(s):  
Oxidative Stress ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Physicochemical Analysis ◽  
The Body ◽  
Oxidative Modification ◽  
Oxidation Products ◽  
Set Up ◽  
Sera Samples

Background. Pro- and antiatherogenic properties of oxidised low density lipoprotein (Ox-LDL) are responsible for different chronic diseases including diabetes and cardiovascular diseases (CVD). The constant attack on the body from oxidative stress makes the quantification of various oxidation products necessary. In this study, the oxidative stress causing the structural and chemical changes occurring in the LDL molecule is comprehensively done. Moreover, the prevalence of the autoantibodies against the oxidised LDL is also determined. Methods. Our study made an attempt to see the effect of Ox-LDL as an enhancer of type 2 diabetes mellitus (T2DM) coupled with CVD. Primarily, we detected the oxidation of LDL with different concentration of Fenton reaction. The biochemical parameters were assessed for the changes occurring in the LDL molecule. In a clinical set up, 20 sera samples were taken from patients who are healthy, 30 from those with diabetes, 20 from those with CVD, and 30 from diabetes with CVD patients. Results. In biochemical assays there were markedly increased TBARS, carbonyl, and HMF content in Ox-LDL as compared to native LDL. The prevalence of autoantibodies against the T2DM was recorded to be 36%, while for CVD it was recorded to be 29%. However, it was found that 50% of the sera samples showed autoantibodies against oxidized LDL in the sera of T2DM with CVD complications as compared to the native analogue. Conclusion. There is significant change in the LDL molecule as revealed by various physicochemical analysis. The change in the LDL macromolecule as a result of oxidation triggered the development of the autoantibodies against it.

Melatonin Improves Lipid Profile and Ameliorates Lipid Peroxidation in Patients with Chronic Kidney Disease.

2018 ◽  
pp. 38-45
Keyword(s):  
Lipid Peroxidation ◽  
Placebo Group ◽  
Lipid Profile ◽  
Kidney Diseases ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Before And After ◽  
Inhibit Lipid Peroxidation ◽  
Controlled Clinical Study

Dyslipidemia and oxidative modifications of lipid are frequently associated in patients with chronic kidney diseases (CKD) and considered the most important risk factors for cardiovascular events. Melatonin is a well-known potent antioxidant and has beneficial effect on lipid metabolism. the study was designed to evaluate if Melatonin could improve lipid profile and ameliorates lipid peroxidation. This single blind placebo controlled clinical study carried out on 41 patients with CKD who were randomized into two groups, control groups (n=20) those who received placebo cap and melatonin group those who received 5mg melatonin (n=21). Lipid profile [total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C)] and parameters of lipid peroxidation [oxidized LDL (oxLDL) and malondialdehyde (MDA) were measured before and after 12 weeks of the treatment. After 12 weeks of treatment, melatonin significantly increased HDL-C and decreased LDL-C compared to the initial value. The elevation in HDL-C and reduction in LDL-C were significantly different from that in placebo group. Also, both oxLDL and MDA levels significantly lowered by melatonin compared to the baseline and to the placebo group. Collectively, the results of our study showed that melatonin has advantageous effect on lipid profile and inhibit lipid peroxidation in patients with CKD.

Glycation and HMG-CoA Reductase Inhibitors: Implication in Diabetes and Associated Complications

2019 ◽  
Vol 15 (3) ◽  
pp. 213-223 ◽  
Author(s):  
Rabia Nabi ◽  
Sahir Sultan Alvi ◽  
Mohd. Saeed ◽  
Saheem Ahmad ◽  
Mohammad Salman Khan
Keyword(s):  
Oxidized Ldl ◽  
Advanced Glycation Endproducts ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Protective Role ◽  
Therapeutic Effects ◽  
Hmg Coa Reductase ◽  
Toxicological Effects ◽  
Coa Reductase

Introduction: Diabetes Mellitus (DM) acts as an absolute mediator of cardiovascular risk, prompting the prolonged occurrence, size and intricacy of atherosclerotic plaques via enhanced Advanced Glycation Endproducts (AGEs) formation. Moreover, hyperglycemia is associated with enhanced glyco-oxidized and oxidized Low-Density Lipoprotein (LDL) possessing greater atherogenicity and decreased the ability to regulate HMG-CoA reductase (HMG-R). Although aminoguanidine (AG) prevents the AGE-induced protein cross-linking due to its anti-glycation potential, it exerts several unusual pharmaco-toxicological effects thus restraining its desirable therapeutic effects. HMG-R inhibitors/statins exhibit a variety of beneficial impacts in addition to the cholesterol-lowering effects. Objective: Inhibition of AGEs interaction with receptor for AGEs (RAGE) and glyco-oxidized-LDL by HMG-R inhibitors could decrease LDL uptake by LDL-receptor (LDL-R), regulate cholesterol synthesis via HMG-R, decrease oxidative and inflammatory stress to improve the diabetes-associated complications. Conclusion: Current article appraises the pathological AGE-RAGE concerns in diabetes and its associated complications, mainly focusing on the phenomenon of both circulatory AGEs and those accumulating in tissues in diabetic nephropathy, diabetic neuropathy, and diabetic retinopathy, discussing the potential protective role of HMG-R inhibitors against diabetic complications.

scholarly journals Oxidized LDL Modifies the Association between Proteinuria and Deterioration of Kidney Function in Proteinuric Diabetic Kidney Disease

Life ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 504
Author(s):  
Stefanos Roumeliotis ◽  
Panagiotis I. Georgianos ◽  
Athanasios Roumeliotis ◽  
Theodoros Eleftheriadis ◽  
Aikaterini Stamou ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Kidney Function ◽  
Diabetic Kidney Disease ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Secondary Outcome ◽  
Diabetic Kidney ◽  
Egfr Decline ◽  
Over Time

Proteinuria is characterized by low accuracy for predicting onset and development of diabetic kidney disease (DKD) because it is not directly associated with molecular changes that promote DKD, but is a result of kidney damage. Oxidized low-density lipoprotein (ox-LDL) reflects oxidative stress and endothelial dysfunction, both underlying the development of proteinuria and loss of kidney function in DKD. We aimed to investigate whether ox-LDL modifies the association between proteinuria and progression of DKD in a cohort of 91 patients with proteinuric DKD and diabetic retinopathy, followed for 10 years. The primary endpoint was a combined kidney outcome of eGFR decline ≥30% or progression to end-stage kidney disease. After the end of the study, we considered the percentage change of eGFR over time as our secondary outcome. Proteinuria was associated with both outcomes, and ox-LDL amplified the magnitude of this link (p < 0.0001 for primary and p < 0.0001 for secondary outcome, respectively). After adjustment for duration of diabetes, history of cardiovascular disease and serum albumin, ox-LDL remained a significant effect modifier of the association between proteinuria and eGFR decline over time (p = 0.04). Our study shows that in proteinuric DKD, circulating ox-LDL levels amplified the magnitude of the association between proteinuria and progression of DKD.

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.

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