Siglec-E retards atherosclerosis by inhibiting CD36-mediated foam cell formation

Abstract Background The accumulation of lipid-laden macrophages, foam cells, within sub-endothelial intima is a key feature of early atherosclerosis. Siglec-E, a mouse orthologue of human Siglec-9, is a sialic acid binding lectin predominantly expressed on the surface of myeloid cells to transduce inhibitory signal via recruitment of SH2-domain containing protein tyrosine phosphatase SHP-1/2 upon binding to its sialoglycan ligands. Whether Siglec-E expression on macrophages impacts foam cell formation and atherosclerosis remains to be established. Methods ApoE-deficient (apoE−/−) and apoE/Siglec-E-double deficient (apoE−/−/Siglec-E−/−) mice were placed on high fat diet for 3 months and their lipid profiles and severities of atherosclerosis were assessed. Modified low-density lipoprotein (LDL) uptake and foam cell formation in wild type (WT) and Siglec-E−/−- peritoneal macrophages were examined in vitro. Potential Siglec-E-interacting proteins were identified by proximity labeling in conjunction with proteomic analysis and confirmed by coimmunoprecipitation experiment. Impacts of Siglec-E expression and cell surface sialic acid status on oxidized LDL uptake and signaling involved were examined by biochemical assays. Results Here we show that genetic deletion of Siglec-E accelerated atherosclerosis without affecting lipid profile in apoE−/− mice. Siglec-E deficiency promotes foam cell formation by enhancing acetylated and oxidized LDL uptake without affecting cholesterol efflux in macrophages in vitro. By performing proximity labeling and proteomic analysis, we identified scavenger receptor CD36 as a cell surface protein interacting with Siglec-E. Further experiments performed in HEK293T cells transiently overexpressing Siglec-E and CD36 and peritoneal macrophages demonstrated that depletion of cell surface sialic acids by treatment with sialyltransferase inhibitor or sialidase did not affect interaction between Siglec-E and CD36 but retarded Siglec-E-mediated inhibition on oxidized LDL uptake. Subsequent experiments revealed that oxidized LDL induced transient Siglec-E tyrosine phosphorylation and recruitment of SHP-1 phosphatase in macrophages. VAV, a downstream effector implicated in CD36-mediated oxidized LDL uptake, was shown to interact with SHP-1 following oxidized LDL treatment. Moreover, oxidized LDL-induced VAV phosphorylation was substantially lower in WT macrophages comparing to Siglec-E−/− counterparts. Conclusions These data support the protective role of Siglec-E in atherosclerosis. Mechanistically, Siglec-E interacts with CD36 to suppress downstream VAV signaling involved in modified LDL uptake.

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Chondroitin Sulfate N -acetylgalactosaminyltransferase-2 Impacts Foam Cell Formation and Atherosclerosis by Altering Macrophage Glycosaminoglycan Chain

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvbaha.120.315789 ◽

2021 ◽

Vol 41 (3) ◽

pp. 1076-1091

Author(s):

Imam Manggalya Adhikara ◽

Keiko Yagi ◽

Dyah Samti Mayasari ◽

Yoko Suzuki ◽

Koji Ikeda ◽

...

Keyword(s):

Chondroitin Sulfate ◽

Foam Cell ◽

Oxidized Ldl ◽

Scavenger Receptor ◽

Cell Formation ◽

Density Lipoprotein ◽

Peritoneal Macrophages ◽

Metabolic Phenotype ◽

Foam Cell Formation ◽

Macrophage Foam Cell

Objective: Chondroitin sulfate proteoglycans are the primary constituents of the macrophage glycosaminoglycan and extracellular microenvironment. To examine their potential role in atherogenesis, we investigated the biological importance of one of the chondroitin sulfate glycosaminoglycan biosynthesis gene, ChGn-2 (chondroitin sulfate N -acetylgalactosaminyltransferase-2), in macrophage foam cell formation. Approach and Results: ChGn-2-deficient mice showed decreased and shortened glycosaminoglycans. ChGn-2 −/− /LDLr −/− (low-density lipoprotein receptor) mice generated less atherosclerotic plaque after being fed with Western diet despite exhibiting a metabolic phenotype similar to that of the ChGn-2 +/+ /LDLr −/− littermates. We demonstrated that in macrophages, ChGn-2 expression was upregulated in the presence of oxLDL (oxidized LDL), and glycosaminoglycan was substantially increased. Foam cell formation was significantly altered by ChGn-2 in both mouse peritoneal macrophages and the RAW264.7 macrophage cell line. Mechanistically, ChGn-2 enhanced oxLDL binding on the cell surface, and as a consequence, CD36—an important macrophage membrane scavenger receptor—was differentially regulated. Conclusions: ChGn-2 alteration on macrophages conceivably influences LDL accumulation and subsequently accelerates plaque formation. These results collectively suggest that ChGn-2 is a novel therapeutic target amenable to clinical translation in the future. Graphic Abstract: A graphic abstract is available for this article.

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Syntheses of diacyltanshinol derivatives and their suppressive effects on macrophage foam cell formation by reducing oxidized LDL uptake

Bioorganic Chemistry ◽

10.1016/j.bioorg.2013.11.001 ◽

2014 ◽

Vol 52 ◽

pp. 24-30 ◽

Cited By ~ 7

Author(s):

Xi Cheng ◽

Da-Li Zhang ◽

Xiao-Bing Li ◽

Jian-Tao Ye ◽

Lei Shi ◽

...

Keyword(s):

Foam Cell ◽

Oxidized Ldl ◽

Cell Formation ◽

Foam Cell Formation ◽

Macrophage Foam Cell ◽

Ldl Uptake

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Plasminogen Deficiency Significantly Reduces Vascular Wall Disease in a Murine Model of Type IIa Hypercholesterolemia

Biomedicines ◽

10.3390/biomedicines9121832 ◽

2021 ◽

Vol 9 (12) ◽

pp. 1832

Author(s):

Takayuki Iwaki ◽

Tomohiro Arakawa ◽

Mayra J. Sandoval-Cooper ◽

Denise L. Smith ◽

Deborah Donahue ◽

...

Keyword(s):

Foam Cell ◽

Low Density Lipoprotein ◽

Cell Formation ◽

Ldl Receptor ◽

Density Lipoprotein ◽

Vascular Wall ◽

Foam Cell Formation ◽

Ldl Uptake ◽

Progression Of Atherosclerosis

The fibrinolytic system has been implicated in the genesis and progression of atherosclerosis. It has been reported that a plasminogen (Pg) deficiency (Plg−/−) exacerbates the progression of atherosclerosis in Apoe−/− mice. However, the manner in which Plg functions in a low-density lipoprotein-cholesterol (LDL-C)-driven model has not been evaluated. To characterize the effect of Pg in an LDL-C-driven model, mice with a triple deficiency of the LDL-receptor (LDLr), along with the active component (apobec1) of the apolipoprotein B editosome complex, and Pg (L−/−/A−/−/Plg−/−), were generated. Atherosclerotic plaque formation was severely retarded in the absence of Pg. In vitro studies demonstrated that LDL uptake by macrophages was enhanced by plasmin (Pm), whereas circulating levels of LDL were enhanced, relative to L−/−/A−/− mice, and VLDL synthesis was suppressed. These results indicated that clearance of lipoproteins in the absence of LDLr may be regulated by Pg/Pm. Conclusions: The results from this study indicate that Pg exacerbates atherosclerosis in an LDL-C model of atherosclerosis and also plays a role in lipoprotein modification and clearance. Therefore, controlling the Pg system on macrophages to prevent foam cell formation would be a novel therapeutic approach.

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Vascular endothelial growth factor modified macrophages transdifferentiate into endothelial-like cells and decrease foam cell formation

Bioscience Reports ◽

10.1042/bsr20170002 ◽

2017 ◽

Vol 37 (3) ◽

Cited By ~ 6

Author(s):

Dan Yan ◽

Yujuan He ◽

Jun Dai ◽

Lili Yang ◽

Xiaoyan Wang ◽

...

Keyword(s):

Vascular Endothelial Growth Factor ◽

Growth Factor ◽

Foam Cell ◽

Oxidized Ldl ◽

Cell Formation ◽

Initial Step ◽

Foam Cell Formation ◽

Vascular Endothelial ◽

Endothelial Growth Factor

Macrophages are largely involved in the whole process of atherosclerosis from an initiation lesion to an advanced lesion. Endothelial disruption is the initial step and macrophage-derived foam cells are the hallmark of atherosclerosis. Promotion of vascular integrity and inhibition of foam cell formation are two important strategies for preventing atherosclerosis. How can we inhibit even the reverse negative role of macrophages in atherosclerosis? The present study was performed to investigate if overexpressing endogenous human vascular endothelial growth factor (VEGF) could facilitate transdifferentiation of macrophages into endothelial-like cells (ELCs) and inhibit foam cell formation. We demonstrated that VEGF-modified macrophages which stably overexpressed human VEGF (hVEGF165) displayed a high capability to alter their phenotype and function into ELCs in vitro. Exogenous VEGF could not replace endogenous VEGF to induce the transdifferentiation of macrophages into ELCs in vitro. We further showed that VEGF-modified macrophages significantly decreased cytoplasmic lipid accumulation after treatment with oxidized LDL (ox-LDL). Moreover, down-regulation of CD36 expression in these cells was probably one of the mechanisms of reduction in foam cell formation. Our results provided the in vitro proof of VEGF-modified macrophages as atheroprotective therapeutic cells by both promotion of vascular repair and inhibition of foam cell formation.

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

Circulation ◽

10.1161/circ.118.suppl_18.s_467-c ◽

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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Regulation of lipoprotein lipase secretion in murine macrophages during foam cell formation in vitro. Effect of triglyceride-rich lipoproteins.

Arteriosclerosis and Thrombosis A Journal of Vascular Biology ◽

10.1161/01.atv.12.12.1458 ◽

1992 ◽

Vol 12 (12) ◽

pp. 1458-1466 ◽

Cited By ~ 11

Author(s):

O Sofer ◽

M Fainaru ◽

Z Schafer ◽

R Goldman

Keyword(s):

Lipoprotein Lipase ◽

Foam Cell ◽

Cell Formation ◽

Foam Cell Formation ◽

Murine Macrophages ◽

Vitro Effect

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Abstract 424: An IFNg-regulated Macrophage Protein Network Links Type 2 Diabetes to Atherosclerosis

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.37.suppl_1.424 ◽

2017 ◽

Vol 37 (suppl_1) ◽

Author(s):

Catherine A Reardon ◽

Amulya Lingaraju ◽

Kelly Q Schoenfelt ◽

Guolin Zhou ◽

Ning-Chun Liu ◽

...

Keyword(s):

Type 2 Diabetes ◽

Foam Cell ◽

Cell Formation ◽

Foam Cell Formation ◽

Increased Risk ◽

Macrophage Dysfunction ◽

Macrophage Protein

Type 2 diabetics have a higher risk for atherosclerosis, but the mechanisms underlying the increased risk are poorly understood. Macrophages, which are activated in type 2 diabetes (T2D) and have a role in all stages of atherogenesis, are an attractive link. Our hypothesis is that T2D promotes macrophage dysfunction to promote atherosclerosis. To investigate the relationship between T2D and macrophage dysfunction, we used a proteomics approach to identify dysregulated proteins secreted from peritoneal macrophages in a diet induced mouse model of obesity and insulin resistance in the absence of hypercholesterolemia. Twenty-seven T2D responsive proteins were identified that predict defects in many of the critical functions of macrophages in atherosclerosis (e.g. decreased apoE- cholesterol efflux; decreased MFGE8 – efferocytosis, increased MMP12- matrix degradation). The macrophages from lean and obese mice were not lipid loaded, but the obese macrophages accumulated significantly more cholesterol when exposed to high levels of atherogenic lipoproteins in vitro suggesting that dysregulation of the T2D responsive proteins in diabetic mice render macrophages more susceptible to cholesterol loading. Importantly, many of these same protein changes, which were present in atherosclerotic Ldlr-/- mice with T2D, were normalized when these mice were fed non-diabetogenic hypercholesterolemic diets. Thus, foam cell formation in the presence and absence of T2D produces distinct effects on macrophage protein levels, and hence function. Further, we identify IFNγ as a mediator of the T2D responsive protein dysfunction. IFNγ, but not other cytokines, insulin or glucose, promote the T2D responsive protein dysregulation and increased susceptibility to cholesterol accumulation in vitro and the dysregulation is not observed in macrophage foam cells obtained from obese, diabetic IFNγ receptor 1 knockout animals. We also demonstrate that IFNγ can target these proteins in arterial wall macrophages in vivo . These studies suggest that IFNγ is an important mediator of macrophage dysfunction in T2D that may contribute to the enhanced cardiovascular risk in these patients.

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Anti-Atherosclerotic Activity of (3R)-5-Hydroxymellein from an Endophytic Fungus Neofusicoccum parvum JS-0968 Derived from Vitex rotundifolia through the Inhibition of Lipoproteins Oxidation and Foam Cell Formation

Biomolecules ◽

10.3390/biom10050715 ◽

2020 ◽

Vol 10 (5) ◽

pp. 715

Author(s):

Jae-Yong Kim ◽

Soonok Kim ◽

Sang Hee Shim

Keyword(s):

Conformational Changes ◽

Endophytic Fungus ◽

Foam Cell ◽

Oxidized Ldl ◽

Cell Formation ◽

Density Lipoprotein ◽

Ldl Oxidation ◽

Foam Cell Formation ◽

Macrophage Foam Cell ◽

Neofusicoccum Parvum

An endophytic fungus, Neofusicoccum parvum JS-0968, was isolated from a plant, Vitex rotundifolia. The chemical investigation of its cultures led to the isolation of a secondary metabolite, (3R)-5-hydroxymellein. It has been reported to have antifungal, antibacterial, and antioxidant activity, but there have been no previous reports on the effects of (3R)-5-hydroxymellein on atherosclerosis. The oxidation of lipoproteins and foam cell formation have been known to be significant in the development of atherosclerosis. Therefore, we investigated the inhibitory effects of (3R)-5-hydroxymellein on atherosclerosis through low-density lipoprotein (LDL) and high-density lipoprotein (HDL) oxidation and macrophage foam cell formation. LDL and HDL oxidation were determined by measuring the production of conjugated dienes and malondialdehyde, the amount of hyperchromicity and carbonyl content, conformational changes, and anti-LDL oxidation. In addition, the inhibition of foam cell formation was measured by Oil red O staining. As a result, (3R)-5-hydroxymellein suppressed the oxidation of LDL and HDL through the inhibition of lipid peroxidation, the decrease of negative charges, the reduction of hyperchromicity and carbonyl contents, and the prevention of apolipoprotein A-I (ApoA-I) aggregation and apoB-100 fragmentation. Furthermore, (3R)-5-hydroxymellein significantly reduced foam cell formation induced by oxidized LDL (oxLDL). Taken together, our data show that (3R)-5-hydroxymellein could be a potential preventive agent for atherosclerosis via obvious anti-LDL and HDL oxidation and the inhibition of foam cell formation.

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