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Abstract Cardiovascular disease is one of the leading causes of death in the elderly, and novel therapeutic targets against atherogenesis are urgent. The initiation of atherosclerotic changes of monocyte adhesion on the vascular endothelium and subsequent foam cell formation are noteworthy pathophysiologies when searching for strategies to prevent the progression of age-related atherosclerosis. We report the significance of the deubiquitinating enzyme cylindromatosis (CYLD) in vascular remodeling by interference with inflammatory responses regulated by NF-κB signaling. The purpose of this study was to elucidate the pathological functions of CYLD in the early phase of atherogenesis associated with aging. Treatment with inflammatory cytokines induced endogenous CYLD in aortic endothelial cells (HAECs) and THP-1 cells. siRNA-mediated CYLD silencing led to enhanced monocyte adhesion along with increased adhesion molecules in HAECs treated with TNFα. In siRNA-mediated CYLD silenced RAW 264.7 macrophages treated with oxidized LDL (oxLDL), augmented lipid accumulation was observed, along with increased expression of the class A macrophage scavenger receptor (SR-A), lectin-like oxidized LDL receptor-1 (LOX-1), CD36, fatty acid binding protein 4 (FABP4), the cholesterol ester synthase acyl-CoA cholesterol acyltransferase (ACAT1), MCP-1, and IL-1β and decreased expression of scavenger receptor class B type I (SR-BI). Intriguingly, CYLD gene expression was significantly reduced in bone marrow-derived macrophages of aged mice compared that of young mice, as well as in senescent HAECs compared with young cells. These findings suggest that age-related attenuation of CYLD expression in endothelial cells (ECs) and macrophages triggers the initiation of age-related atherogenesis by exacerbating monocyte adhesion on the endothelium and foam cell formation. CYLD in the vasculature may be a novel therapeutic target, especially in the early preventive intervention against the initiation of age-related atherogenesis. Highlights • Inflammatory cytokines induce endogenous CYLD in endothelial cells and macrophages. • CYLD silencing in inflamed endothelial cells leads to enhanced monocyte adhesion. • CYLD silencing in macrophages augments lipid accumulation. • CYLD expression is reduced in macrophages and endothelial cells with aging. [ABSTRACT FROM AUTHOR]

Abstract Aims The accumulation of lipids in macrophages contributes to the development of atherosclerosis. Cholesterol efflux of lipid-loaded macrophages mediated by ATP binding cassette (ABC) cholesterol transporters, on the other hand, has been shown to attenuate atherosclerosis progression in patients with unknown mechanism. We therefore sought to test the effect of metformin that reduced cardiovascular risk in diabetic patients independent of its hypoglycemia effect on cholesterol transport in murine raw264.7 macrophages. Materials and methods Mouse raw264.7 macrophages were loaded with Ox-LDL (50 μg/ml) for 24 h before incubated with metformin (15 μM) for 24 h. Foam cell formation was assessed by Oil red staining and BIODIPY fluorescent staining as well as cholesterol-ester quantification by commercial kit. Cholesterol uptake and expression of scavenger receptors were detected by flow-cytometry. Cholesterol efflux capacity was measured by fluorescent plate-reader and ABC transporters were detected by Western Blots. Cytokines were detected by ELISA in supernatants and normalized by cellular lysates. Key findings Our results showed that metformin decreased oxidized low-density lipoprotein (Ox-LDL)-induced cholesterol accumulation and foam cell formation by increasing cholesterol efflux to HDL, which was associated with an upregulation of ABC transporter ABCG-1. Moreover, metformin increased Ox-LDL-impaired IL-10 secretion, an important anti-foam cell cytokine in atherosclerosis. Significance Our data highlighted the therapeutic potential of targeting macrophage cholesterol efflux with new or existing drugs for the possible reduction of foam cell formation in the prevention and treatment of diabetes-accelerated atherosclerosis. [ABSTRACT FROM AUTHOR]

Abstract During atherosclerosis, the gradual accumulation of lipids into the subendothelial space of damaged arteries results in several lipid modification processes followed by macrophage uptake in the arterial wall. The way in which these modified lipoproteins are dealt with determines the likelihood of cholesterol accumulation within the monocyte-derived macrophage and thus its transformation into the foam cell that makes up the characteristic fatty streak observed in the early stages of atherosclerosis. The unique expression of chemokine receptors and cellular adhesion molecules expressed on the cell surface of monocytes points to a particular extravasation route that they can take to gain entry into atherosclerotic site, in order to undergo differentiation into the phagocytic macrophage. Indeed several GWAS and animal studies have identified key genes and proteins required for monocyte recruitment as well cholesterol handling involving lipid uptake, cholesterol esterification and cholesterol efflux. A re-examination of the previously accepted paradigm of macrophage foam cell origin has been called into question by recent studies demonstrating shared expression of scavenger receptors, cholesterol transporters and pro-inflammatory cytokine release by alternative cell types present in the neointima, namely; endothelial cells, vascular smooth muscle cells and stem/progenitor cells. Thus, therapeutic targets aimed at a more heterogeneous foam cell population with shared functions, such as enhanced protease activity, and signalling pathways, mediated by non-coding RNA molecules, may provide greater therapeutic outcome in patients. Finally, studies targeting each aspect of foam cell formation and death using both genetic knock down and pharmacological inhibition have provided researchers with a clearer understanding of the cellular processes at play, as well as helped researchers to identify key molecular targets, which may hold significant therapeutic potential in the future. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Objective · To screen the anti-atherosclerosis (AS) activity of the compoundsusing THP-1-HIF-1α-HER-Luciferase high-throughput model, and to verify the anti-AS function of the effective compounds. Methods · THP-1-HIF-1α-HER-Luciferase cells were pretreated with different concentrations of compounds (1, 10, and 100 μg/mL) for 2 h, then cultured under hypoxia for 24 h. Luciferase activity of cells was detected and compounds with anti-AS activity were screenedluciferase activity evaluation. THP-1 and U937 cells were pretreated with effective compounds, and then induced for 24 hoxidized low density lipoprotein (OX-LDL). The formation of foam cells was observedoil red staining. The mRNA level of hypoxia-inducible factor 1α (HIF-1α) was detectedreal-time quantitative PCR (qPCR). HIF-1α protein was detectedWestern blotting. Anti-AS activity of effective compounds were evaluated. Results · Among the 200 compounds, 11 compounds could significantly inhibit the increase of luciferase activity in THP-1-HIF-1α-HER-Luciferase cells inducedhypoxia (all P<0.05), and compound numbered 14 (C14) had the most significant inhibitory effect. THP-1 and U937 cells formed foam cells induced for 24 hOX-LDL. However, cells were pretreated with C14 for 2 h, which could significantly inhibit the formation of foam cells inducedOX-LDL. Cells were induced for 24 hOX-LDL, which could significantly increase the of HIF-1α mRNA and protein (all P<0.05), while cells pretreated with C14 could significantly inhibit the increase of HIF-1α mRNA and protein in a gradient-dependent manner (all P<0.05). Conclusion · THP-1-HIF-1α-HER-Luciferase high-throughput model can be reliability used in screening of compounds with anti-AS activity. C14 has the good anti-AS activity characteristics. [ABSTRACT FROM AUTHOR]

Atherosclerosis is a chronic immune inflammatory disease. Aspirin eugenol ester (AEE) is a novel safe and non-toxic compound with many pharmacological effects such as anti-inflammatory, anti-hyperlipidemic and anti-thrombotic action. In order to investigate the effect of AEE on the inhibition of aortic lipid plaque formation and macrophage-derived foam cell formation induced by oxidized low density lipoprotein (ox-LDL), in vivo atherosclerosis model by feeding ApoE-/- mice with a high-fat diet and foam cells formation in vitro model by ox-LDL-induced RAW264.7 macrophages were established. It was found that AEE decreased the levels of TC and LDL-C in serum, and the plaque formation area and lipid accumulation in the aortic intima of ApoE-/- mice. In vitro studies showed that AEE could prevent the uptake of ox-LDL and reduce the contents of TC and FC in cells. AEE enhanced the cholesterol efflux by increasing the expression of ABCA1, ABCG1 and PPARγ, which effectively alleviated excess cholesterol accumulated in the cells. Meanwhile, AEE also reduced the secretion and expression of inflammatory factors in the cells. In addition, AEE could reverse the action of PPARγ inhibitor T0070907 and/or ox-LDL. Therefore, AEE may become an effective candidate drug for the prevention of atherosclerosis. [Display omitted] • AEE prevents atherosclerosis and alleviates macrophage foaminess. • AEE promotes cholesterol efflux and reduces the content of intracellular lipids. • AEE inhibits NF-κB p65 expression and increases PPARγ expression to inhibit inflammation. [ABSTRACT FROM AUTHOR]

• Lipid-laden macrophages are observed in the lung in vivo following pulmonary injury, and this phenotype may significantly contribute to pulmonary pathologies. • This phenotype is proposed to form due to the imbalance between lipid acquisition, metabolism, storage, and export. • The complex interplay between metabolism and storage of lipids are discussed as they pertain to disease progression. • Herein, we discuss critical regulators and signaling pathways that may play a role in the formation of lipid-laden macrophages in the lung. • The consequences of lipid-laden macrophage formation within the context of pulmonary inflammation are considered. Uniquely positioned as sentinel cells constantly exposed to the environment, pulmonary macrophages are vital for the maintenance of the lung lining. These cells are responsible for the clearance of xenobiotics, pathogen detection and clearance, and homeostatic functions such as surfactant recycling. Among the spectrum of phenotypes that may be expressed by macrophages in the lung, the pulmonary lipid-laden phenotype is less commonly studied in comparison to its circulatory counterpart, the atherosclerotic lesion-associated foam cell, or the acutely activated inflammatory macrophage. Herein, we propose that lipid-laden macrophage formation in the lung is governed by lipid acquisition, storage, metabolism, and export processes. The cellular balance of these four processes is critical to the maintenance of homeostasis and the prevention of aberrant signaling that may contribute to lung pathologies. This review aims to examine mechanisms and signaling pathways that are involved in lipid-laden macrophage formation and the potential consequences of this phenotype in the lung. [ABSTRACT FROM AUTHOR]

To assess whether drinking tea can effectively prevent smoking-induced atherosclerosis, a clinical trial ex vivo study was performed. The volunteers were randomly allocated to two groups (n = 55 per group) that received either Pu-erh tea powder or a cellulose placebo (0.5 g/capsule, T.I.D.) for two months. The circulating monocytes were isolated from the tested individuals after 0, 1, and 2 months of tea-capsule administration. We found that monocytes displaying high α9-nicotinic-acetylcholine-receptor (α9-nAchR) expression that were isolated from heavy smokers before consuming tea capsules tended to form foam cells in response to nicotine (1 µL for 24 h, *P

In this study LC n-3 PUFA-specific effects on the degree of monocyte differentiation and macrophage foam cell formation were investigated by treating PMA-induced immature and mature macrophage models with LC n-3/n-6 PUFA during and post-differentiation. During immature macrophage differentiation LC n-3 PUFA alone decreased TNFα mRNA levels. EPA, and the n-6 PUFAs, linoleic acid and arachidonic acid, decreased CD36 mRNA levels, and EPA also downregulated CD49d cell-surface expression. Both LC n-3 PUFA reduced LDLr mRNA levels in immature macrophages, while DHA alone reduced levels in mature macrophages. Post-differentiation, n-3 and -6 PUFA reduced basal, but not oxidised LDL dependent cholesterol levels in immature macrophages. LC n-3 PUFA-specific reductions in LDLr and LOX-1 mRNA expression were also observed.This study found LC n-3 PUFA specific, anti-atherogenic effects were more significant in immature macrophages. LC n-3 PUFA effects may be modulated by the extent of monocyte to macrophage differentiation.

The antihyperlipidaemic effect of an ethanol extract of Ramulus mori containing a high concentration of oxyresveratrol (ERMO) was investigated in a high-cholesterol diet (HCD)-fed rat model. Cholesterol metabolism-related genes and proteins, such as lecithin cholesterol acyltransferase (LCAT), low-density lipoprotein receptor (LDLR), cholesterol 7α-hydroxylase (CYP7A1), 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) and acyl coenzyme A cholesterol acyltransferase-2 (ACAT2) were analysed by quantitative real-time reverse-transcription polymerase chain reaction and western blot analysis. ERMO-treated HCD-fed rats had decreased body and liver weights and reduced serum lipid levels, atherogenic index (AI) and coronary artery risk index (CRI). ERMO treatment lowered serum cholesterol levels by increasing the expression of LCAT, CYP7A1 and LDLR and by decreasing HMGCR and ACAT2. Histological analysis of liver and aortic tissues revealed a significant decrease in lipid droplets and foam cell formation in HCD-induced hyperlipidaemic rats treated with ERMO. ERMO is therefore a potentially potent functional food for preventing hyperlipidaemia.

Mechanisms of lipid homeostasis and its impairment are of crucial importance for atherogenesis, and their understanding is necessary for successful development of new therapeutic approaches. In the arterial wall, macrophages play a prominent role in intracellular lipid accumulation, giving rise to foam cells that populate growing atherosclerotic plaques. Under normal conditions, macrophages are able to process substantial amounts of lipids and cholesterol without critical overload of the catabolic processes. However, in atherosclerosis, these pathways become inefficient, leading to imbalance in cholesterol and lipid metabolism and disruption of cellular functions. In this review, we summarize the existing knowledge on the involvement of macrophage lipid metabolism in atherosclerosis development, including both the results of recent studies and classical concepts, and provide a detailed description of these processes from the moment of lipid uptake with lipoproteins to cholesterol efflux.

The formation of foam cells, which are macrophages that have engulfed oxidized low-density lipoprotein (OxLDL), constitutes the first stage in the development of atherosclerosis. Previously, we found that knocking down galectin-12, a negative regulator of lipolysis, leads to reduced secretion of monocyte chemoattractant protein-1 (MCP-1), a chemokine that plays an important role in atherosclerosis. This prompted us to study the role of galectin-12 in atherosclerosis. With that aim, we examined foam cell formation in Gal12‒/‒ murine macrophages exposed to OxLDL and acetylated LDL (AcLDL). Then, we generated an LDL receptor and galectin-12 double knockout (DKO) mice and studied the effect of galectin-12 on macrophage function and atherosclerosis. Lastly, we evaluated the role of galectin-12 in human THP-1 macrophages using a doxycycline-inducible conditional knockdown system. Galectin-12 knockout significantly inhibited foam cell formation in murine macrophages through the downregulation of cluster of differentiation 36 (CD36), and the upregulation of ATP Binding Cassette Subfamily A Member 1 (ABCA1), ATP Binding Cassette Subfamily G Member 1 (ABCG1), and scavenger receptor class B type 1 (SRB1). Consistent with this, galectin-12 knockdown inhibited foam cell formation in human macrophages. In addition, the ablation of galectin-12 promoted M2 macrophage polarization in human and murine macrophages as evidenced by the upregulation of the M2 marker genes, CD206 and CD163, and downregulation of the M1 cytokines, tumor necrosis factor α (TNF- α), interleukin-6 (IL-6), and MCP-1. Moreover, the ablation of galectin-12 decreased atherosclerosis formation in DKO mice. Based on these results, we propose galectin-12 as a potential therapeutic target for atherosclerosis.

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.

Atherosclerosis is the major cause of cardiovascular diseases. Current evidences indicate that inflammation is involved in the pathogenesis of atherosclerosis. Human gingiva-derived mesenchymal stem cells (GMSC) have shown anti-inflammatory and immunomodulatory effects on autoimmune and inflammatory diseases. However, the function of GMSC in controlling atherosclerosis is far from clear. The present study is aimed to elucidate the role of GMSC in atherosclerosis, examining the inhibition of GMSC on macrophage foam cell formation, and further determining whether GMSC could affect the polarization and activation of macrophages under different conditions. The results show that infusion of GMSC to AopE−/− mice significantly reduced the frequency of inflammatory monocytes/macrophages and decreased the plaque size and lipid deposition. Additionally, GMSC treatment markedly inhibited macrophage foam cell formation and reduced inflammatory macrophage activation, converting inflammatory macrophages to anti-inflammatory macrophages in vitro. Thus, our study has revealed a significant role of GMSC on modulating inflammatory monocytes/macrophages and alleviating atherosclerosis.

BACKGROUND: A high fat diet, accompanied by high frequency eating, results in hyperlipidemia. One prevention for hyperlipidemia is administration of celery extract. OBJECTIVE: to explore the effect of celery extract on the level of 8-OHdG (8 -Hydroxy-2’-Deoxy Guanosine) and the number of foam cell. METHODS: Experimental studies with post-test only control group design used Wistar rats, administered with adrenaline and high-fat diet for hyperlipidemic induction.Total of 35 rats were divided into 5 groups: negative controls (Neg-G); positive control treated with simvastatin (Nor-G); ES25-G,ES50-G, and ES75-G group were treated with 25 mg/200 g BW, 50 mg/200 g BW, and 75 mg/200 g BW celery extract, respectively. The treatment was given for 30 days. The 8-OHdG level was determined by ELISA, whereas the number of foam cells was determined by histopathologic preparations with HE staining. Data analysis was conducted by Kruskal-Wallis and Mann-Whitney. RESULTS: Mann-Whitney analysis showed levels of 8-OHdG in ES-25-G 12.13±0.21, ES-50-G 7.23±0.25, ES-75-G 4.41±0.45 significantly lower than the Nor-G 14.30±0.66, respectively p

Foam cell formation is a very common pathologic finding in atherosclerosis, often found in some major organs. However, the involvement of the retroperitoneal organs is very rare and foam cell formation associated with borderline ovarian tumor has not been reported. Borderline ovarian tumors are epithelial ovarian tumors with a low growth rate, low potential to invade or metastasize, and excellent prognosis. Still, a rapidly growing borderline ovarian tumor can exert pressure on the retroperitoneal organs. It may cause retroperitoneal irritation and inflammation, and form a mass lesion in adjacent organs. We report the case of a 41-year-old woman with a borderline ovarian tumor and foam cell infiltration. [ABSTRACT FROM AUTHOR]

Macrophage-derived foam cell formation is considered to be a critical step in the development of atherosclerosis. In the present study, we evaluated the inhibitory effect of Ilex kudingcha triterpenoid-enriched extract (TS) on foam cell formation in THP-1 macrophage cells induced by aggregated low density lipoproteins (agLDL). The inhibition of low density lipoprotein receptor-related protein 1 (LRP1) expression after TS treatment is based on mRNA and protein levels in the macrophages. These inductions were sterol regulatory element-binding protein-2 (SREBP2) dependent. On the basis of the in vitro results, the anti-atherosclerotic activity of TS was investigated in ApoE−/− mice fed a high-fat diet, ApoE−/− mice treated with TS for 6 weeks appeared to have decreased aortic sinus lesions compared with the untreated mice. These findings indicate that TS may act as an anti-atherosclerotic agent.

Bioassay-guided evaluation shows that a deep sea-derived fungus, Spiromastix sp. MCCC 3A00308, possesses lipid-lowering activity. Chromatographic separation of a culture broth resulted in the isolation of 15 known depsidone-based analogues, labeled spiromastixones A–O (1–15). Each of these compounds was tested for its ability to inhibit oxidized low-density lipoprotein (oxLDL)-induced foam cell formation in RAW264.7 macrophages. Spiromastixones 6–8 and 12–14 significantly decreased oxLDL-induced lipid over-accumulation, reduced cell surface area, and reduced intracellular cholesterol concentration. Of these compounds, spiromastixones 6 and 14 exerted the strongest inhibitory effects. Spiromastixones 6 and 14 dramatically inhibited cholesterol uptake and stimulated cholesterol efflux to apolipoprotein A1 (ApoA1) and high-density lipoprotein (HDL) in RAW264.7 macrophages. Mechanistic investigation indicated that spiromastixones 6, 7, 12 and 14 significantly up-regulated the mRNA levels of ATP-binding cassette sub-family A1 (ABCA1) and down-regulated those of scavenger receptor CD36, while the transcription of ATP-binding cassette sub-family A1 (ABCG1) and proliferator-activated receptor gamma (PPARγ) were selectively up-regulated by 6 and 14. A transactivation reporter assay revealed that spiromastixones 6 and 14 remarkably enhanced the transcriptional activity of PPARγ. These results suggest that spiromastixones inhibit foam cell formation through upregulation of PPARγ and ABCA1/G1 and downregulation of CD36, indicating that spiromastixones 6 and 14 are promising lead compounds for further development as anti-atherogenic agents.

Atherosclerosis is considered an inflammatory disease. However, clinically used anti-atherosclerotic drugs, such as simvastatin, have many side effects. Recently, several unique marine compounds have been isolated that possess a variety of bioactivities. In a previous study, we found a synthetic precursor of the marine compound (austrasulfone), which is dihydroaustrasulfone alcohol (WA-25), has anti-atherosclerotic effects in vivo. However, the detailed mechanisms remain unclear. Therefore, to clarify the mechanisms through which WA-25 exerts anti-atherosclerotic activity, we used RAW 264.7 macrophages as an in vitro model to evaluate the effects of WA-25. In lipopolysaccharide (LPS)-stimulated RAW 264.7 cells, WA-25 significantly inhibited expression of the pro-inflammatory proteins, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In contrast, simvastatin increased the COX-2 expression compared to WA-25. In addition, WA-25 impedes foam cell formation and up-regulated the lysosomal and cyclic adenosine monophosphate (cAMP) signaling pathway. We also observed that transforming growth factor β1 (TGF-β1) was up-regulated by WA-25 and simvastatin in LPS-induced RAW 264.7 cells, and the promising anti-atherosclerosis effects of WA-25 were disrupted by blockade of TGF-β1 signaling. Besides, WA-25 might act through increasing lipolysis than through alteration of lipid export. Taken together, these data demonstrate that WA-25 may have potential as an anti-atherosclerotic drug with anti-inflammatory effects.

Atherosclerosis has a high incidence and is harmful to human health. An elevated level of oxidized low-density lipoprotein (Ox-LDL) is one of the major risk factors for atherosclerosis. During atherogenesis progression, circulating monocytes adhere to the intima and differentiate into macrophages. After differentiation, intimal macrophages intake Ox-LDL via scavenger receptors, thereby transforming into foam cells. Foam cell formation due to excessive accumulation of cholesterol by macrophages is a pathological hallmark of atherosclerosis. To gain a molecular understanding of the effect of Ox-LDL in atherosclerosis development, we conducted a genome-wide analysis of the Ox-LDL-induced macrophage transformation by microarray gene expression profiling. Here we describe in details the contents and quality controls for the gene expression and related results associated with the data uploaded to Gene Expression Omnibus (accession number GSE54039).

Cholesterol-rich, apolipoprotein B (apoB)-containing lipoproteins are now widely accepted as the most important causal agents of atherosclerotic cardiovascular disease. Multiple unequivocal and orthogonal lines of evidence all converge on low-density lipoprotein and related particles as being the principal actors in the genesis of atherosclerosis. Here, we review the fundamental role of atherogenic apoB-containing lipoproteins in cardiovascular disease and several other humoral and parietal factors that are required to initiate and maintain arterial degeneration. The biology of foam cells and their interactions with high-density lipoproteins, including cholesterol efflux, are also briefly reviewed.

Supplemental Digital Content is available in the text. Background: Although the role of thrombin in atherothrombosis is well studied, its role in the pathogenesis of diet-induced atherosclerosis is not known. Methods: Using a mouse model of diet-induced atherosclerosis and molecular biological approaches, here we have explored the role of thrombin and its G protein-coupled receptor signaling in diet-induced atherosclerosis. Results: In exploring the role of G protein-coupled receptor signaling in atherogenesis, we found that thrombin triggers foam cell formation via inducing CD36 expression, and these events require Par1-mediated Gα12-Pyk2-Gab1-protein kinase C (PKC)θ-dependent ATF2 activation. Genetic deletion of PKCθ in apolipoprotein E (ApoE)−/− mice reduced Western diet-induced plaque formation. Furthermore, thrombin induced Pyk2, Gab1, PKCθ, and ATF2 phosphorylation, CD36 expression, and foam cell formation in peritoneal macrophages of ApoE−/− mice. In contrast, thrombin only stimulated Pyk2 and Gab1 but not ATF2 phosphorylation or its target gene CD36 expression in the peritoneal macrophages of ApoE−/−:PKCθ−/− mice, and it had no effect on foam cell formation. In addition, the aortic root cross-sections of Western diet-fed ApoE−/− mice showed increased Pyk2, Gab1, PKCθ, and ATF2 phosphorylation and CD36 expression as compared with ApoE−/−:PKCθ−/− mice. Furthermore, although the monocytes from peripheral blood and the aorta of Western diet-fed ApoE−/− mice were found to contain more of Ly6Chi cells than Ly6Clo cells, the monocytes from Western diet-fed ApoE−/−:PKCθ−/− mice were found to contain more Ly6Clo cells than Ly6Chi cells. It is interesting to note that the Ly6Chi cells showed higher CD36 expression with enhanced capacity to form foam cells as compared with Ly6Clo cells. Conclusions: These findings reveal for the first time that thrombin-mediated Par1-Gα12 signaling via targeting Pyk2-Gab1-PKCθ-ATF2-dependent CD36 expression might be playing a crucial role in diet-induced atherogenesis. [ABSTRACT FROM AUTHOR]

Host lipid metabolism is an important target for subversion by pathogenic mycobacteria such as Mycobacterium tuberculosis . The appearance of foam cells within the granuloma are well-characterised effects of chronic tuberculosis. The zebrafish- Mycobacterium marinum infection model recapitulates many aspects of human-M. tuberculosis infection and is used as a model to investigate the structural components of the mycobacterial granuloma. Here, we demonstrate that the zebrafish- M. marinum granuloma contains foam cells and that the transdifferentiation of macrophages into foam cells is driven by the mycobacterial ESX1 pathogenicity locus. This report demonstrates conservation of an important aspect of mycobacterial infection across species. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • LAIR-1 was down-regulated in macrophage with the stimulation of ox-LDL. • Silencing expression of LAIR-1 in human macrophages increased cholesterol uptake. • LAIR-1 activated phosphorylation of SHP-1 and CREB to induce PPARγ, thus promoting M2 polarization and foam cell formation. • Targeting LAIR-1 may provide a potential therapeutic strategy for atherosclerosis. Abstract Formation of macrophage-derived foam cells may mark the initial stages of atherosclerosis. We investigated the association between the expression of the leukocyte-associated immunoglobulin-like receptor 1 (LAIR-1) in macrophages and foam cell formation. A foam cell model was established by incubating THP-1-derived macrophages and bone marrow macrophages (BMMs) with oxidized low-density lipoprotein (ox-LDL). The role of LAIR-1 in foam cell formation was evaluated via Oil Red O staining and Dil-ox-LDL fluorescence intensities. Peroxisome proliferator-activated receptor gamma (PPARγ), cholesterol metabolism-related genes, and the role of LAIR-1 in activating classically activated (M1) and alternatively activated (M2) macrophages were evaluated by qPCR. Additionally, activation of protein-tyrosine phosphatase-1 (SHP-1) and cAMP-response element binding protein (CREB) were detected by western blotting. Results indicated that silencing LAIR-1 in macrophages modulated the SHP-1/CREB/PPARγ pathway, thereby promoting M2 macrophage polarization and increasing foam cell formation. Therefore, Inhibition of LAIR-1 in macrophages may promote foam cell formation and atherosclerosis. [ABSTRACT FROM AUTHOR]

Abstract The formation of macrophage foam cells by ingesting ox-LDL and focal retention in the subendothelial space are the hallmarks of the early atherosclerotic lesion. The C-C chemokine receptor type 7 (CCR7) is positively correlated with the macrophage migration. But the mechanism of CCR7 regulation is not fully clearness. In the present study, we demonstrates that expression in UNC5b and netrin-1 was enhanced in respond to ox-LDL in Raw264.7 macrophage and associated with decreasing cell migration. Interestingly, it was found that ox-LDL significantly downregulate CCR7 gene expression. The expression of CCR7 in mRNA and protein levels were decreased in ox-LDL treated Raw264.7 macrophage when we over expression of UNC5b with pcDNA3.1-UNC5b plasmid. We got the inverse results after silence UNC5b gene with siUNC5b. Meanwhile, the data show that in ox-LDL inducement, UNC5b down-regulated CCR7, and then inhibited macrophage migration. This novel phenomenon is of a crucial highlights to understand deeply the pathogenesis of atherosclerosis. The molecular mechanism of CCR7 regulation deserves intensive study. Highlights ∙ The netrin-1, and its receptor UNC5b, are expressed by macrophage foam cells. ∙ The up-regulation of UNC5b and netrin-1 was in respond to ox-LDL in Raw264.7 macrophage, and was associated with decreasing cell migration. ∙ In ox-LDL inducement, UNC5b down-regulated CCR7, and then inhibited macrophage migration. [ABSTRACT FROM AUTHOR]

Bile acids, initially discovered as endogenous ligands of farnesoid X receptor (FXR), play a central role in the regulation of triglyceride and cholesterol metabolism and have recently emerged as a privileged structure for interacting with nuclear receptors relevant to a large array of metabolic processes. In this paper, phenoxy containing cholic acid derivatives with excellent drug-likeness have been designed, synthesized, and assayed as agents against cholesterol accumulation in Raw264.7 macrophages. The most active compound 14b reduced total cholesterol accumulation in Raw264.7 cells up to 30.5% at non-toxic 10 μM and dosage-dependently attenuated oxLDL-induced foam cell formation. Western blotting and qPCR results demonstrate that 14b reduced both cholesterol and lipid in Raw264.7 cells through (1) increasing the expression of cholesterol transporters ABCA1 and ABCG1, (2) accelerating ApoA1-mediated cholesterol efflux. Through a cell-based luciferase reporter assay and molecular docking analysis, LXR was identified as the potential target for 14b . Interestingly, unlike conventional LXR agonist, 14b did not increase lipogenesis gene SREBP-1c expression. Overall, these diverse properties disclosed herein highlight the potential of 14b as a promising lead for further development of multifunctional agents in the therapy of cardiovascular disease. [ABSTRACT FROM AUTHOR]

Histone modifications are the key epigenetic mechanisms that have been identified to regulate gene expression in many human diseases. However, in the early developmental stages, such as in utero and the postnatal stages, histone modifications are essential for gene regulation and cell growth. Atherosclerosis represents a classical example of the involvement of different cell types, and their cumulative effects in the development of atheroma and the progression of the disease. Post translational modifications on proteins either induces their functional activity or renders them inactive. Post translational modifications such as methylation or acetylation on histones have been well characterized, and their role in enhancing or inhibiting specific gene expression was clearly elucidated. In the present review article, the critical roles of different histone modifications that occur in atherosclerosis have been summarized. Different histone proteins have been identified to serve a critical role in the development of atherosclerosis. Specifically, histone methylation and histone acetylation in monocytes, macrophages, vascular smooth muscle cells and in endothelial cells during the progression of atherosclerosis, have been well reported. In recent years, different target molecules and genes that regulate histone modifications have been examined for their effects in the treatment of atherosclerosis in animal models and in clinical trials. An increasing body of evidence suggests that these epigenetic changes resulting from DNA methylation and non‑coding RNA may also be associated with histone modifications, thereby indicating that novel therapeutic strategies can be developed by targeting these post translational modifications, which may in turn aid in the treatment of atherosclerosis. [ABSTRACT FROM AUTHOR]

Mindin, which is a highly conserved extracellular matrix protein, has been documented to play pivotal roles in regulating angiogenesis, inflammatory processes, and immune responses. The aim of the present study was to assess whether mindin contributes to the development of atherosclerosis. A significant up-regulation of Mindin expression was observed in the serum, arteries and atheromatous plaques of ApoE−/− mice after high-fat diet treatment. Mindin−/−ApoE−/− mice and macrophage-specific mindin overexpression in ApoE−/− mice (Lyz2-mindin-TG) were generated to evaluate the effect of mindin on the development of atherosclerosis. The Mindin−/−ApoE−/− mice exhibited significantly ameliorated atherosclerotic burdens in the entire aorta and aortic root and increased atherosclerotic plaque stability. Moreover, bone marrow transplantation further demonstrated that mindin deficiency in macrophages was largely responsible for the alleviated atherogenesis. The Lyz2-mindin-TG mice exhibited the opposite phenotype. Mindin deficiency enhanced foam cell formation by increasing the expression of cholesterol effectors, including ABCA1 and ABCG1. The mechanistic study indicated that mindin ablation promoted LXR-β expression via a direct interaction. Importantly, LXR-β inhibition largely reversed the ameliorating effect of mindin deficiency on foam cell formation and ABCA1 and ABCG1 expression. The present study demonstrated that mindin deficiency serves as a novel mediator that protects against foam cell formation and atherosclerosis by directly interacting with LXR-β. [ABSTRACT FROM AUTHOR]

Background: CD36 is a multi-functional class B scavenger receptor, which acts as an important modulator of lipid homeostasis and immune responses. Sources of data: This review uses academic articles. Areas of agreement: CD36 is closely related to the development and progression of atherosclerosis. Areas of controversy: Both persistent up-regulation of CD36 and deficiency of CD36 increase the risk for atherosclerosis. Abnormally up-regulated CD36 promotes inflammation, foam cell formation, endothelial apoptosis, macrophage trapping and thrombosis. However, CD36 deficiency also causes dyslipidemia, subclinical inflammation and metabolic disorders, which are established risk factors for atherosclerosis. Growing points: There may be an 'optimal protective window' of CD36 expression. Areas timely for developing research: In addition to traditionally modulating protein functions using gene overexpression or deficiency, the modulation of CD36 function at post-translational levels has recently been suggested to be a potential therapeutic strategy. [ABSTRACT FROM AUTHOR]

Background and aims Wnt5a is a highly studied member of the Wnt family and recently has been implicated in the pathogenesis of atherosclerosis, but its precise role is unknown. Foam cell development is a critical process to atherosclerotic plaque formation. In the present study, we investigated the role of noncanonical Wnt5a signaling in the development of foam cells. Methods Human carotid atherosclerotic tissue and THP-1-derived macrophages were used to investigate the contribution of Wnt5a signaling in the formation of foam cells. Immunohistochemistry was used to evaluate protein expression of scavenger receptors and noncanonical Wnt5a receptors [frizzled 5 (Fz5) and receptor tyrosine kinase-like orphan receptor 2 (Ror2)] in human atherosclerotic macrophages/foam cells. Changes in protein expression in response to Wnt5a stimulation/inhibition were determined by Western blot, and lipid accumulation was evaluated by fluorescent lipid droplet staining. Results Wnt5a ( P <.05), Fz5 ( P <.01), and Ror2 ( P <.01) were significantly expressed in advanced atherosclerotic lesions compared to less advanced lesions ( N =10). Wnt5a, Fz5, and Ror2 were expressed in macrophages/foam cells within the plaque. In vitro studies revealed that Wnt5a significantly increased the expression of the lipid uptake receptor CD36 ( P <.05) but not the lipid efflux receptor ATP-binding cassette transporter ( P >.05). rWnt5a also significantly increased lipid accumulation in THP-1 macrophages ( P <.05). Furthermore, inhibition of Wnt5a signaling with Box5 prevented lipid accumulation ( P <.01) and prevented CD36 up-regulation ( P <.01). Conclusions These results suggest a direct role for Wnt5a signaling in the pathogenesis of atherosclerosis, specifically the accumulation of lipid in macrophages and the formation of foam cells. [ABSTRACT FROM AUTHOR]

Atherosclerosis is the major cause of cardiovascular diseases. Current evidences indicate that inflammation is involved in the pathogenesis of atherosclerosis. Human gingiva-derived mesenchymal stem cells (GMSC) have shown anti-inflammatory and immuno-modulatory effects on autoimmune and inflammatory diseases. However, the function of GMSC in controlling atherosclerosis is far from clear. The present study is aimed to elucidate the role of GMSC in atherosclerosis, examining the inhibition of GMSC on macrophage foam cell formation, and further determining whether GMSC could affect the polarization and activation of macrophages under different conditions. The results show that infusion of GMSC to AopE-/- mice significantly reduced the frequency of inflammatory monocytes/macrophages and decreased the plaque size and lipid deposition. Additionally, GMSC treatment markedly inhibited macrophage foam cell formation and reduced inflammatory macrophage activation, converting inflammatory macrophages to anti-inflammatory macrophages in vitro. Thus, our study has revealed a significant role of GMSC on modulating inflammatory monocytes/macrophages and alleviating atherosclerosis. [ABSTRACT FROM AUTHOR]

Abstract: Obesity‐related changes in adipose tissue leukocytes, in particular adipose tissue macrophages (ATMs) and dendritic cells (ATDCs), are implicated in metabolic inflammation, insulin resistance, and altered regulation of adipocyte function. We evaluated stromal cell and white adipose tissue (WAT) expansion dynamics with high fat diet (HFD) feeding for 3–56 days, quantifying ATMs, ATDCs, endothelial cells (ECs), and preadipocytes (PAs) in visceral epididymal WAT and subcutaneous inguinal WAT. To better understand mechanisms of the early response to obesity, we evaluated ATM proliferation and lipid accumulation. ATMs, ATDCs, and ECs increased with rapid WAT expansion, with ATMs derived primarily from a CCR2‐independent resident population. WAT expansion stimulated proliferation in resident ATMs and ECs, but not CD11c+ ATMs or ATDCs. ATM proliferation was unperturbed in Csf2‐ and Rag1‐deficient mice with WAT expansion. Additionally, ATM apoptosis decreased with WAT expansion, and proliferation and apoptosis reverted to baseline with weight loss. Adipocytes reached maximal hypertrophy at 28 days of HFD, coinciding with a plateau in resident ATM accumulation and the appearance of lipid‐laden CD11c+ ATMs in visceral epididymal WAT. ATM increases were proportional to tissue expansion and adipocyte hypertrophy, supporting adipocyte‐mediated regulation of resident ATMs. The appearance of lipid‐laden CD11c+ ATMs at peak adipocyte size supports a role in responding to ectopic lipid accumulation within adipose tissue. In contrast, ATDCs increase independently of proliferation and may be derived from circulating precursors. These changes precede and establish the setting in which large‐scale adipose tissue infiltration of CD11c+ ATMs, inflammation, and adipose tissue dysfunction contributes to insulin resistance. [ABSTRACT FROM AUTHOR]

Background Many studies have identified trimethylamine N-oxide (TMAO) as a new risk factor of cardiovascular diseases. It has been suggested that TMAO promotes atherosclerosis development. However, the underlying mechanism is still unclear. Methods Apoe-/- mice were fed a high-fat diet and given water with or without TMAO for 8-week. Histological and immunohistological analyses were used to evaluate the atherogenic effect of TMAO in vivo. We also employed peritoneal elicited macrophages and RAW264.7 to assess the role of MAPK/JNK pathway in TMAO-induced formation of foam cells. Results TMAO significantly promoted plaque progression in apoe-/- mice fed with high-fat diet for 8 weeks. Besides, macrophage recruitment, CD36 and proinflammatory cytokine expressions were enhanced by TMAO in plaque lesions. In vitro, TMAO increased the macrophage migration and the expression of TNF-α, IL-6 and ICAM1. In addition, CD36 expression and foam cell formation induced by ox-LDL were also enhanced by TMAO, which could be attenuated by siRNA-mediated knockdown of CD36. We additionally used MAPK inhibitor (SB230580) and JNK inhibitor (SP600125) to assess the MAPK/JNK pathway in TMAO-induced CD36 expression. Western blotting showed that both SB230580 and SP600125 could reduce the expression of CD36 induced by ox-LDL and TMAO. Moreover, SB230580 and SP600125 could also reduce the formation of foam cells. Conclusions TMAO promotes the atherosclerosis in vivo and in vitro.CD36/MAPK/JNK pathway may play a crucial role in TMAO-induced formation of foam cells. [ABSTRACT FROM AUTHOR]

Background: The transformation of normal macrophage cells into lipid-laden foam cells is an important step in the progression of atherosclerosis. One major contributor to foam cell formation in vivo is the intracellular accumulation of cholesterol. Methods: Here, we report the effects of various combinations of low-density lipoprotein, sterols, lipids and other factors on human macrophages, using an automated image analysis program to quantitatively compare single cell properties, such as cell size and lipid content, in different conditions. Results: We observed that the addition of cholesterol caused an increase in average cell lipid content across a range of conditions. All of the sterol-lipid mixtures examined were capable of inducing increases in average cell lipid content, with variations in the distribution of the response, in cytotoxicity and in how the sterol-lipid combination interacted with other activating factors. For example, cholesterol and lipopolysaccharide acted synergistically to increase cell lipid content while also increasing cell survival compared with the addition of lipopolysaccharide alone. Additionally, ergosterol and cholesteryl hemisuccinate caused similar increases in lipid content but also exhibited considerably greater cytotoxicity than cholesterol. Conclusions: The use of automated image analysis enables us to assess not only changes in average cell size and content, but also to rapidly and automatically compare population distributions based on simple fluorescence images. Our observations add to increasing understanding of the complex and multifactorial nature of foam-cell formation and provide a novel approach to assessing the heterogeneity of macrophage response to a variety of factors. [ABSTRACT FROM AUTHOR]