Abstract 126: Chlamydia Pneumoniae Induces Foam Cell Formation Of Macrophages By Activating The TLR4/TRIF/IRF3 Pathway

Background: Chlamydia pneumoniae (CP) induces macrophage foam cell formation (FCF), a key event in early atherosclerosis, in the presence of low-density lipoprotein (LDL). Recent studies have indicated the role of Toll-Like Receptors in atherogenesis. Liver X receptors (LXR) are nuclear receptors that play central roles in the transcriptional control of lipid metabolism and determinants of atherosclerosis. Induction of LXR-activated genes has also been shown to influence the pathogen pattern recognition activity of the Toll-like receptors 3 and 4 (TLR3/4). The TLR and the LXR pathways converge on the transcription factor IRF3. Objective: We hypothesized that TLR and the LXR and IRF3 pathways participate in CP infection mediated FCF and acceleration of atherosclerosis, and that the MyD88- independent pathway via TLR4/TRIF and IRF3 play a role in this acceleration. Methods: Peritoneal macrophages were isolated from C57BL/6 wild type (WT) mice, IRF3 −/− mice, TLR4 −/− mice and TRIF −/− mice. Cells were treated with UV killed CP (UVCP, 5x10 5 IFU) with or without ox-LDL (100 μg/ml) in the presence or absence of LXR agonist GW3965 (2nM). LPS (10 ng/ml) and PolyI:C (1μg/ml) were used as positive controls as TLR4 and TLR3 ligands, respectively. FCF was examined by Oil Red O staining. The percentages of foam cells in total macrophages were quantified. Results : FCF was significantly reduced in IRF3−/− cells compared with WT cells stimulated with UVCP plus ox-LDL. Foam cells induced by LPS with ox-LDL were also significantly reduced in IRF3−/− cells compared to WT cells (p<0.05). Furthermore, the synthetic LXR agonist GW3965 significantly diminished CP induced FCF in WT cells. FCF was significantly reduced in TLR4−/− and TRIF−/− macrophages compared to WT cells when stimulated with UVCP with ox-LDL (p<0.05). Conclusion : Chlamydia pneumoniae infection can activate the TLR4/TRIF/IRF3 pathway and does play an important role in CP- mediated foam cell formation in macrophages. Therefore, infections such as the one caused by CP, can trigger the TLR4/TRIF/IRF3 pathway leading to the down regulation of LXRs and shifting of cholesterol transport toward pro-foam cell production and thereby accelerating atherogenesis.. Supported by NIH grants AI 067995 and HL66436 to MA.

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Koala Biovar of Chlamydia pneumoniae Infects Human and Koala Monocytes and Induces Increased Uptake of Lipids In Vitro

Infection and Immunity ◽

10.1128/iai.69.12.7894-7897.2001 ◽

2001 ◽

Vol 69 (12) ◽

pp. 7894-7897 ◽

Cited By ~ 6

Author(s):

Katie A. Coles ◽

Peter Timms ◽

David W. Smith

Keyword(s):

Chlamydia Pneumoniae ◽

Foam Cell ◽

Low Density Lipoprotein ◽

Cell Formation ◽

Density Lipoprotein ◽

Foam Cells ◽

Foam Cell Formation ◽

Low Density ◽

Human Monocytes

ABSTRACT We examined the ability of the koala biovar of Chlamydia pneumoniae to infect both Hep-2 cells and human monocytes and the effect of infection on the formation of foam cells. The koala biovar produced large inclusions in both human and koala monocytes and in Hep-2 cells. Koala C. pneumoniae induced foam cell formation with and without added low-density lipoprotein, in contrast to TW183, which produced increased foam cell formation only in the presence of low-density lipoprotein.

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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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Chlamydia pneumoniae-Induced Macrophage Foam Cell Formation Is Mediated by Toll-Like Receptor 2

Infection and Immunity ◽

10.1128/iai.01386-06 ◽

2006 ◽

Vol 75 (2) ◽

pp. 753-759 ◽

Cited By ~ 106

Author(s):

Fei Cao ◽

Antonio Castrillo ◽

Peter Tontonoz ◽

Fabio Re ◽

Gerald I. Byrne

Keyword(s):

Chlamydia Pneumoniae ◽

Foam Cell ◽

Cell Formation ◽

Foam Cells ◽

Foam Cell Formation ◽

Toll Like Receptor ◽

Macrophage Foam Cell ◽

E Coli ◽

Toll Like Receptor 2 ◽

Ce Content

ABSTRACT Chlamydia pneumoniae induces macrophage foam cell formation, a hallmark of early atherosclerosis, in the presence of low-density lipoprotein (LDL). This study examined the role that Toll-like receptor 2 (TLR2) and TLR4 may play in pathogen-induced foam cell formation. Murine macrophage RAW 264.7 cells either infected with C. pneumoniae or treated with the TLR4 ligand E. coli lipopolysaccharide (LPS) or the TLR2 ligand Pam3-Cys-Ala-Gly-OH (Pam) became Oil Red O-stained foam cells and showed increased cholesteryl ester (CE) content when cocultured with LDL. In macrophages from TLR2−/− mice, foam cells were induced by Escherichia coli LPS but not by C. pneumoniae or Pam. Conversely, C. pneumoniae or Pam, but not E. coli LPS, induced foam cells in the TLR4-deficient GG2EE macrophage cell line, suggesting that C. pneumoniae elicits foam cell formation predominantly via TLR2. Enhancing cholesterol efflux using the liver X receptor (LXR) agonist GW3965 significantly decreased the CE content of cells exposed to each of the three TLR ligands (C. pneumoniae, Pam, and E. coli LPS). Overall, our results suggest that activation of the LXR signaling pathway may affect potentially atherogenic processes modulated by the TLR ligands.

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Phagocytosis of lipase-aggregated low density lipoprotein promotes macrophage foam cell formation. Sequential morphological and biochemical events.

Arteriosclerosis and Thrombosis A Journal of Vascular Biology ◽

10.1161/01.atv.11.6.1643 ◽

1991 ◽

Vol 11 (6) ◽

pp. 1643-1651 ◽

Cited By ~ 37

Author(s):

J W Heinecke ◽

A G Suits ◽

M Aviram ◽

A Chait

Keyword(s):

Foam Cell ◽

Low Density Lipoprotein ◽

Cell Formation ◽

Density Lipoprotein ◽

Foam Cell Formation ◽

Low Density ◽

Macrophage Foam Cell

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Inhibitory effects of vasostatin-1 against atherogenesis

Clinical Science ◽

10.1042/cs20180451 ◽

2018 ◽

Vol 132 (23) ◽

pp. 2493-2507 ◽

Cited By ~ 2

Author(s):

Yuki Sato ◽

Rena Watanabe ◽

Nozomi Uchiyama ◽

Nana Ozawa ◽

Yui Takahashi ◽

...

Keyword(s):

Adhesion Molecule ◽

Inflammatory Responses ◽

Foam Cell ◽

Cell Formation ◽

Density Lipoprotein ◽

Foam Cell Formation ◽

Inhibitory Effects ◽

Macrophage Foam Cell ◽

Down Regulation ◽

Atherosclerotic Lesions

Vasostatin-1, a chromogranin A (CgA)-derived peptide (76 amino acids), is known to suppress vasoconstriction and angiogenesis. A recent study has shown that vasostatin-1 suppresses the adhesion of human U937 monocytes to human endothelial cells (HECs) via adhesion molecule down-regulation. The present study evaluated the expression of vasostatin-1 in human atherosclerotic lesions and its effects on inflammatory responses in HECs and human THP-1 monocyte-derived macrophages, macrophage foam cell formation, migration and proliferation of human aortic smooth muscle cells (HASMCs) and extracellular matrix (ECM) production by HASMCs, and atherogenesis in apolipoprotein E-deficient (ApoE−/−) mice. Vasostatin-1 was expressed around Monckeberg’s medial calcific sclerosis in human radial arteries. Vasostatin-1 suppressed lipopolysaccharide (LPS)-induced up-regulation of monocyte chemotactic protein-1 (MCP-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin in HECs. Vasostatin-1 suppressed inflammatory M1 phenotype and LPS-induced interleukin-6 (IL-6) secretion via nuclear factor-κB (NF-κB) down-regulation in macrophages. Vasostatin-1 suppressed oxidized low-density lipoprotein (oxLDL)-induced foam cell formation associated with acyl-CoA:cholesterol acyltransferase-1 (ACAT-1) and CD36 down-regulation and ATP-binding cassette transporter A1 (ABCA1) up-regulation in macrophages. In HASMCs, vasostatin-1 suppressed angiotensin II (AngII)-induced migration and collagen-3 and fibronectin expression via decreasing ERK1/2 and p38 phosphorylation, but increased elastin expression and matrix metalloproteinase (MMP)-2 and MMP-9 activities via increasing Akt and JNK phosphorylation. Vasostatin-1 did not affect the proliferation and apoptosis in HASMCs. Four-week infusion of vasostatin-1 suppressed the development of aortic atherosclerotic lesions with reductions in intra-plaque inflammation, macrophage infiltration, and SMC content, and plasma glucose level in ApoE−/− mice. These results indicate the inhibitory effects of vasostatin-1 against atherogenesis. The present study provided the first evidence that vasostatin-1 may serve as a novel therapeutic target for atherosclerosis.

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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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Signaling Pathways and Key Genes Involved in Regulation of foam Cell Formation in Atherosclerosis

Cells ◽

10.3390/cells9030584 ◽

2020 ◽

Vol 9 (3) ◽

pp. 584 ◽

Cited By ~ 16

Author(s):

Anastasia V. Poznyak ◽

Wei-Kai Wu ◽

Alexandra A. Melnichenko ◽

Reinhard Wetzker ◽

Vasily Sukhorukov ◽

...

Keyword(s):

Foam Cell ◽

Low Density Lipoprotein ◽

Cell Formation ◽

Density Lipoprotein ◽

Foam Cells ◽

Foam Cell Formation ◽

Beneficial Effects ◽

Complex Process ◽

Experimental Therapies ◽

Inflammatory Drugs

Atherosclerosis is associated with acute cardiovascular conditions, such as ischemic heart disease, myocardial infarction, and stroke, and is the leading cause of morbidity and mortality worldwide. Our understanding of atherosclerosis and the processes triggering its initiation is constantly improving, and, during the last few decades, many pathological processes related to this disease have been investigated in detail. For example, atherosclerosis has been considered to be a chronic inflammation triggered by the injury of the arterial wall. However, recent works showed that atherogenesis is a more complex process involving not only the immune system, but also resident cells of the vessel wall, genetic factors, altered hemodynamics, and changes in lipid metabolism. In this review, we focus on foam cells that are crucial for atherosclerosis lesion formation. It has been demonstrated that the formation of foam cells is induced by modified low-density lipoprotein (LDL). The beneficial effects of the majority of therapeutic strategies with generalized action, such as the use of anti-inflammatory drugs or antioxidants, were not confirmed by clinical studies. However, the experimental therapies targeting certain stages of atherosclerosis, among which are lipid accumulation, were shown to be more effective. This emphasizes the relevance of future detailed investigation of atherogenesis and the importance of new therapies development.

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Combination Therapy with a Sodium-Glucose Cotransporter 2 Inhibitor and a Dipeptidyl Peptidase-4 Inhibitor Additively Suppresses Macrophage Foam Cell Formation and Atherosclerosis in Diabetic Mice

International Journal of Endocrinology ◽

10.1155/2017/1365209 ◽

2017 ◽

Vol 2017 ◽

pp. 1-9 ◽

Cited By ~ 5

Author(s):

Michishige Terasaki ◽

Munenori Hiromura ◽

Yusaku Mori ◽

Kyoko Kohashi ◽

Hideki Kushima ◽

...

Keyword(s):

Combination Therapy ◽

Foam Cell ◽

Cell Formation ◽

Peritoneal Macrophages ◽

Foam Cell Formation ◽

Diabetic Mice ◽

Macrophage Foam Cell ◽

Dipeptidyl Peptidase 4 ◽

Sodium Glucose Cotransporter ◽

Hba1c Levels

Dipeptidyl peptidase-4 inhibitors (DPP-4is), in addition to their antihyperglycemic roles, have antiatherosclerotic effects. We reported that sodium-glucose cotransporter 2 inhibitors (SGLT2is) suppress atherosclerosis in a glucose-dependent manner in diabetic mice. Here, we investigated the effects of combination therapy with SGLT2i and DPP-4i on atherosclerosis in diabetic mice. SGLT2i (ipragliflozin, 1.0 mg/kg/day) and DPP-4i (alogliptin, 8.0 mg/kg/day), either alone or in combination, were administered to db/db mice or streptozotocin-induced diabetic apolipoprotein E-null (Apoe−/−) mice. Ipragliflozin and alogliptin monotherapies improved glucose intolerance; however, combination therapy did not show further improvement. The foam cell formation of peritoneal macrophages was suppressed by both the ipragliflozin and alogliptin monotherapies and was further enhanced by combination therapy. Although foam cell formation was closely associated with HbA1c levels in all groups, DPP-4i alone or the combination group showed further suppression of foam cell formation compared with the control or SGLT2i group at corresponding HbA1c levels. Both ipragliflozin and alogliptin monotherapies decreased scavenger receptors and increased cholesterol efflux regulatory genes in peritoneal macrophages, and combination therapy showed additive changes. In diabetic Apoe−/− mice, combination therapy showed the greatest suppression of plaque volume in the aortic root. In conclusion, combination therapy with SGLT2i and DPP4i synergistically suppresses macrophage foam cell formation and atherosclerosis in diabetic mice.

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