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ABSTRACT: Abstract Objective: Lysophosphatidic acid (LPA), a bioactive lysophospholipid, accumulates in the atherosclerotic plaque. It has the capacity to activate mast cells, which potentially exacerbates plaque progression. In this study, we thus aimed to investigate whether LPA contributes to plaque destabilization by modulating mast cell function. Methods and Results: We here show by an imaging mass spectrometry approach that several LPA species are present in atherosclerotic plaques. Subsequently, we demonstrate that LPA is a potent mast cell activator, which unlike other triggers favor release of tryptase. Local perivascular administration of LPA to an atherosclerotic carotid artery segment increases the activation status of perivascular mast cells and promotes intraplaque hemorrhage, macrophage recruitment, without impacting plaque cell apoptosis. The mast cell stabilizer cromolyn could prevent intraplaque hemorrhage elicited by LPA-mediated mast cell activation. Finally, the involvement of mast cells in these events was further emphasized by the lack of effect of perivascular LPA administration in mast cell deficient animals. Conclusions: We demonstrate that increased accumulation of LPA in plaques induces perivascular mast cell activation and in this way contribute to plaque destabilization in vivo. This study points to local LPA availability as an important factor in atherosclerotic plaque stability.
The Journal of Lipid Research 02/2013; · 5.56 Impact Factor
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ABSTRACT: OBJECTIVE: Despite common disbelief that neutrophils are involved in atherosclerosis, evidence is accumulating for a causal role of neutrophils in atherosclerosis. CCL3 is an inflammatory chemokine and its expression is significantly increased during atherosclerotic lesion formation in mice. It has recently been shown that under conditions of inflammation neutrophils can migrate along a CCL3 gradient. In this study, we aimed to elucidate the role of leukocyte-derived CCL3 in atherogenesis. METHODS AND RESULTS: Irradiated LDLr(-/-) mice, reconstituted with CCL3(-/-) or littermate bone marrow showed markedly reduced CCL3 response to lipopolysaccharide treatment, establishing the critical relevance of leukocytes as source of CCL3. Hematopoietic deficiency of CCL3 significantly reduced aortic sinus lesion formation by 31% after 12 weeks of western-type diet. Interestingly, whereas plaque macrophage, collagen, and vSMC content were unchanged, neutrophil adhesion to and presence in plaques was significantly attenuated in CCL3(-/-) chimeras. These mice had reduced circulating neutrophil numbers, which could be ascribed to an increased neutrophil turnover and CCL3(-/-) neutrophils were shown to be less responsive toward the neutrophil chemoattractant CXCL1. CONCLUSIONS: Our data indicate that under conditions of acute inflammation leukocyte-derived CCL3 can induce neutrophil chemotaxis toward the atherosclerotic plaque, thereby accelerating lesion formation.
Arteriosclerosis Thrombosis and Vascular Biology 01/2013; · 6.37 Impact Factor
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ABSTRACT: OBJECTIVE: Costimulatory molecules tightly control immune responses by providing positive signals that promote T-cell activation or by transducing inhibitory signals that limit T-cell responses. CD30 and CD30L are members of the tumor necrosis factor receptor superfamily and are involved in the activation and proliferation of T and B cells, which have been implicated in the initiation and progression of atherosclerosis. In the present study, we thus aimed to determine the role of the CD30-CD30L pathway in the development of atherosclerosis. METHODS AND RESULTS: Western-type diet-fed low-density lipoprotein receptor-deficient mice were treated with an anti-CD30L antibody for 8 weeks, which resulted in a reduction of atherosclerotic lesion formation in the aortic root by 35%. Reduced numbers of adventitial CD3(+) T cells were found in anti-CD30L-treated mice, whereas no differences were observed in collagen and macrophage content of the atherosclerotic lesions. B-cell and mast cell responses were also not affected on anti-CD30L treatment. Interestingly, splenocyte proliferation was reduced by 53%, whereas T-cell numbers were concomitantly reduced in anti-CD30L-treated mice compared with control mice. These data thus indicate that the CD30-CD30L pathway solely exerts its function via inhibition of T-cell responses. CONCLUSIONS: In the present study, we are the first to show that interruption of the CD30-CD30L pathway reduced initial atherosclerosis development by modulating T-cell function.
Arteriosclerosis Thrombosis and Vascular Biology 10/2012; · 6.37 Impact Factor
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ABSTRACT: AIMS: Failure of vein graft conduits due to vein graft thickening, accelerated atherosclerosis and subsequent plaque rupture is applicable to 50% of all vein grafts within 10 years. New potential therapeutic targets to treat vein graft disease may be found in components of the innate immune system, such as mast cells and complement factors, which are known to be involved in atherosclerosis and plaque destabilization. Interestingly, mast cells can be activated by complement factor C5a and therefore a direct role for C5a mediated mast cell activation in vein graft disease is anticipated. We hypothesize that C5a mediated mast cell activation is involved in the development and destabilization of vein graft lesions.Methods and ResultsMast cells accumulated in time in murine vein graft lesions and C5a and C5a-receptor (CD88) expression was up-regulated during vein graft disease in Apolipoprotein E- deficient mice. Mast cell activation with dinitrophenyl resulted in a profound increase in vein graft thickening and in the number of plaque disruptions. C5a application enhanced vein graft lesion formation, while treatment with a C5a-receptor antagonist resulted in decreased vein graft disease. C5a most likely exerts its function via mast cell activation since the mast cell inhibitor cromolyn totally blocked C5a enhanced vein graft disease. CONCLUSIONS: These data provide evidence that complement factor C5a induced mast cell activation is highly involved in vein graft disease, which identifies new targets to prevent vein graft disease.
Cardiovascular research 10/2012; · 5.80 Impact Factor
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Ilze Bot,
Henk de Vries,
Suzanne J A Korporaal,
Amanda C Foks,
Martine Bot,
Jacobus van Veldhoven,
Mariëtte N D Ter Borg,
Peter J van Santbrink,
Theo J C van Berkel, Johan Kuiper,
Adriaan P Ijzerman
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ABSTRACT: The A(2B) adenosine receptor (A(2B)R) is highly expressed in macrophages and vascular smooth muscle cells and has been established as an important regulator of inflammation and vascular adhesion. Recently, it has been demonstrated that A(2B)R deficiency enhances neointimal lesion formation after vascular injury. Therefore, we hypothesize that A(2B)R agonism protects against injury-induced intimal hyperplasia.
Apolipoprotein E-deficient mice were fed a Western-type diet for 1 week, after which the left common carotid artery was denuded. Mice were treated with the A(2B) receptor agonist BAY60-6583 or vehicle control for 18 days. Interestingly, lumen stenosis as defined by the neointima/lumen ratio was inhibited by treatment with the A(2B) receptor agonist, caused by reduced smooth muscle cell proliferation. Collagen content was significantly increased in the BAY60-6583-treated mice, whereas macrophage content remained unchanged. In vitro, vascular smooth muscle cell proliferation decreased dose dependently whereas collagen content of cultured smooth muscle cells was increased by BAY60-6583.
Our data show that activation of the adenosine A(2B) receptor protects against vascular injury, while it also enhances plaque stability as indicated by increased collagen content. These outcomes thus point to A(2B) receptor agonism as a new therapeutic approach in the prevention of restenosis.
Arteriosclerosis Thrombosis and Vascular Biology 06/2012; 32(9):2197-205. · 6.37 Impact Factor
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Laura Calpe-Berdiel,
Ying Zhao,
Marjo de Graauw,
Dan Ye,
Peter J van Santbrink,
A Mieke Mommaas,
Amanda Foks,
Martine Bot,
Illiana Meurs, Johan Kuiper,
Jody T Mack,
Miranda Van Eck,
Kenneth D Tew,
Theo J C van Berkel
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ABSTRACT: The ABCA2 transporter shares high structural homology to ABCA1, which is crucial for the removal of excess cholesterol from macrophages and, by extension, in atherosclerosis. It has been suggested that ABCA2 sequesters cholesterol inside the lysosomes, however, little is known of the macrophage-specific role of ABCA2 in regulating lipid homeostasis in vivo and in modulating susceptibility to atherosclerosis.
Chimeras with dysfunctional macrophage ABCA2 were generated by transplantation of bone marrow from ABCA2 knockout (KO) mice into irradiated LDL receptor (LDLr) KO mice.
Interestingly, lack of ABCA2 in macrophages resulted in a diminished lesion size in the aortic root (-24.5%) and descending thoracic aorta (-36.6%) associated with a 3-fold increase in apoptotic cells, as measured by both caspase 3 and TUNEL. Upon oxidized LDL exposure, macrophages from wildtype (WT) transplanted animals developed filipin-positive droplets in lysosomal-like compartments, corresponding to free cholesterol (FC) accumulation. In contrast, ABCA2-deficient macrophages displayed an abnormal diffuse distribution of FC over peripheral regions. The accumulation of neutral sterols in lipid droplets was increased in ABCA2-deficient macrophages, but primarily in cytoplasmic clusters and not in lysosomes. Importantly, apoptosis of oxLDL loaded macrophages lacking ABCA2 was increased 2.7-fold, probably as a consequence of the broad cellular distribution of FC.
Lack of functional ABCA2 generates abnormalities in intracellular lipid distribution/trafficking in macrophages consistent with its lysosomal sequestering role, leading to an increased susceptibility to apoptosis in response to oxidized lipids and reduced atherosclerotic lesion development.
Atherosclerosis 06/2012; 223(2):332-41. · 3.79 Impact Factor
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Jacco C Karper,
Mark M Ewing,
Kim L L Habets,
Margreet R de Vries,
Erna A B Peters,
Annemarie M van Oeveren-Rietdijk,
Hetty C de Boer,
Jaap F Hamming, Johan Kuiper,
Ekambar R Kandimalla,
Nicola La Monica,
J Wouter Jukema,
Paul H A Quax
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ABSTRACT: The role of toll-like receptors (TLRs) in vascular remodeling is well established. However, the involvement of the endosomal TLRs is unknown. Here, we study the effect of combined blocking of TLR7 and TLR9 on postinterventional remodeling and accelerated atherosclerosis.
In hypercholesterolemic apolipoprotein E*3-Leiden mice, femoral artery cuff placement led to strong increase of TLR7 and TLR9 presence demonstrated by immunohistochemistry. Blocking TLR7/9 with a dual antagonist in vivo reduced neointimal thickening and foam cell accumulation 14 days after surgery by 65.6% (P=0.0079). Intima/media ratio was reduced by 64.5% and luminal stenosis by 62.8%. The TLR7/9 antagonist reduced the arterial wall inflammation, with reduced macrophage infiltration, decreased cytoplasmic high-mobility group box 1 expression, and altered serum interleukin-10 levels. Stimulation of cultured macrophages with TLR7 and TLR9 ligands enhanced tumor necrosis factor-α expression, which is decreased by TLR7/9 antagonist coadministration. Additionally, the antagonist abolished the TLR7/9-enhanced low-density lipoprotein uptake. The antagonist also reduced oxidized low-density lipoprotein-induced foam cell formation, most likely not via decreased influx but via increased efflux, because CD36 expression was unchanged whereas interleukin-10 levels were higher (36.1 ± 22.3 pg/mL versus 128.9 ± 6.6 pg/mL; P=0.008).
Blocking TLR7 and TLR9 reduced postinterventional vascular remodeling and foam cell accumulation indicating TLR7 and TLR9 as novel therapeutic targets.
Arteriosclerosis Thrombosis and Vascular Biology 05/2012; 32(8):e72-80. · 6.37 Impact Factor
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Illiana Meurs,
Laura Calpe-Berdiel,
Kim L L Habets,
Ying Zhao,
Suzanne J A Korporaal,
A Mieke Mommaas,
Emmanuelle Josselin,
Reeni B Hildebrand,
Dan Ye,
Ruud Out, Johan Kuiper,
Theo J C Van Berkel,
Giovanna Chimini,
Miranda Van Eck
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ABSTRACT: ABCA7, a close relative of ABCA1 which facilitates cholesterol efflux to lipid-poor apoproteins, has been implicated in macrophage lipid efflux and clearance of apoptotic cells in in vitro studies. In the current study, we investigated the in vivo effects of macrophage ABCA7 deficiency on lipid metabolism and atherosclerosis. Chimeras with dysfunctional ABCA7 in macrophages and other blood cells were generated by transplantation of bone marrow from ABCA7 knockout (KO) mice into irradiated low-density lipoprotein receptor (LDLr) KO mice. Unexpectedly, macrophage ABCA7 deficiency did not significantly affect atherosclerosis susceptibility of LDLr KO mice after 10 weeks Western-type diet feeding. However, ABCA7 deficiency was associated with 2-fold (p<0.05) higher macrophage ABCA1 mRNA expression levels. Combined disruption of ABCA1 and ABCA7 in bone-marrow-derived cells increased atherosclerotic lesion development (1.5-fold (p>0.05) as compared to wild type transplanted mice. However, single deletion of ABCA1 had a similar effect (1.8-fold, p<0.05). Macrophage foam cell accumulation in the peritoneal cavity was reduced in ABCA1/ABCA7 dKO transplanted animals as compared to single ABCA1 KO transplanted mice, which was associated with increased ABCG1 expression. Interestingly, spleens of ABCA1/ABCA7 double KO transplanted mice were significantly larger as compared to the other 3 groups and showed massive macrophage lipid accumulation, a reduction in CD3+ T-cells, and increased expression of key regulators of erythropoiesis. In conclusion, deletion of ABCA7 in bone marrow-derived cells does not affect atherogenesis in the arterial wall neither in the absence or presence of ABCA1. Interestingly, combined deletion of bone marrow ABCA1 and ABCA7 causes severe splenomegaly associated with cellular lipid accumulation, a reduction in splenic CD3+ T cells, and induced markers of erythropoeisis. Our data indicate that ABCA7 may play a role in T cell proliferation and erythropoeisis in spleen.
PLoS ONE 01/2012; 7(3):e30984. · 4.09 Impact Factor
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ABSTRACT: ATP-binding cassette transporter A1 (ABCA1) is an important mediator of macrophage cholesterol efflux. It mediates the efflux of cellular cholesterol to lipid-poor apolipoprotein A-I. LDL receptor (LDLr) knockout (KO) mice deficient for leukocyte ABCA1 (ABCA1 KO→LDLr KO) show increased atherosclerosis and splenic lipid accumulation despite largely attenuated serum cholesterol levels. In the present study, we aimed to explore the importance of the spleen for the atheroprotective effects of leukocyte ABCA1.
LDLr KO mice were transplanted with bone marrow from ABCA1 KO mice or wild-type (WT) controls. After 8 weeks recovery, mice were either splenectomized (SP-x) or underwent a sham operation, and were subsequently challenged with a Western-type diet (WTD).
In agreement with previous studies, the atherosclerotic lesion area in ABCA1 KO→LDLr KO sham animals (655±82×10(3) µm(2)) was 1.4-fold (p = 0.03) larger compared to sham WT→LDLr KO mice (459±33×10(3) µm(2)) after 8 weeks WTD feeding, despite 1.7-fold (p<0.001) lower serum cholesterol levels. Interestingly, deletion of ABCA1 in leukocytes led to 1.6-fold higher neutrophil content in the spleen in absence of differences in circulating neutrophils. Levels of KC, an important chemoattractant for neutrophils, in serum, however, were increased 2.9-fold (p = 0.07) in ABCA1 KO→LDLr KO mice. SP-x induced blood neutrophilia as compared to WT→LDLr KO mice (1.9-fold; p<0.05), but did not evoke differences in serum cholesterol and anti-oxLDL antibody levels. Atherosclerotic lesion development, however, was 1.3-fold induced both in the presence and absence of leukocyte ABCA1 (WT: 614±106×10(3) µm(2), ABCA1 KO: 786±44×10(3) µm(2)). Two-way ANOVA revealed independent effects on atherosclerosis for both leukocyte ABCA1 deficiency and SP-x (p<0.05).
The observed splenic alterations induced by leukocyte ABCA1 deficiency do not play a significant role in the anti-atherogenic effects of leukocyte ABCA1 on lesion development.
PLoS ONE 01/2012; 7(10):e48080. · 4.09 Impact Factor
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Illiana Meurs,
Laura Calpe-Berdiel,
Kim L L Habets,
Ying Zhao,
Suzanne J A Korporaal,
A Mieke Mommaas,
Emmanuelle Josselin,
Reeni B Hildebrand,
Dan Ye,
Ruud Out, Johan Kuiper,
Theo J C Van Berkel,
Giovanna Chimini,
Miranda Van Eck
PLoS ONE 01/2012; 7(5). · 4.09 Impact Factor
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ABSTRACT: Bifunctional, pH-activatable BODIPY dyes were developed and incorporated in mannose cluster-containing activity-based probes for cysteine proteases. Mannose receptor-dependent uptake of the probes in dendritic cells, followed by trafficking to acidic cellular compartments resulted in fluorescence as seen by live-cell imaging, and subsequent cathepsin inhibition.
Chemical Communications 09/2011; 47(33):9363-5. · 6.17 Impact Factor
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ABSTRACT: MicroRNAs modulate processes associated with cell cycle control and differentiation. Here we explored the potential of microRNAs in the modulation of hepatic lipid metabolism and the development of nonalcoholic fatty liver disease. MicroRNA profiles of hepatocytes from low-density lipoprotein (LDL) receptor knockout mice fed a chow diet or a hypertriglyceridemia/fatty liver-inducing Western-type diet (WTD) were determined using quantitative real-time polymerase chain reaction. Ninety-seven of 103 microRNAs measured were expressed by hepatocytes and low variability between hepatocyte pools was observed. Feeding WTD coincided with a marked fivefold decrease in the relative expression level of miR-216 (P<.05) and miR-302a (P<.01). Interestingly, an increased hepatic miR-216 expression was detected in response to fasting. MicroRNA/biological function linkage analysis suggested that the change in hepatocyte microRNA profiles in response to high dietary lipid levels is associated with changes in cell cycle control and proliferation. In accordance with a diminished miR-302a expression on the WTD, hepatocyte mRNA expression levels of miR-302a target genes ABCA1 and in particular ELOVL6 were increased in response to WTD (twofold to ninefold). This suggests a role for miR-302a in hepatic cholesterol, fatty acid and glucose metabolism. In conclusion, we have shown that fatty liver development in LDL receptor knockout mice is associated with a significant change in the hepatocyte microRNA profile, i.e., a fivefold decrease in miR-216 and miR-302a expression. Based upon our comparative gene and microRNA expression studies it is anticipated that miR-302a may prove to be a valuable therapeutic target in the regulation of hepatic fatty acid utilization and insulin resistance.
The Journal of nutritional biochemistry 07/2011; 23(6):622-8. · 4.29 Impact Factor
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Man C Wong,
Janna A van Diepen,
Lihui Hu,
Bruno Guigas,
Hetty C de Boer,
Gijs H van Puijvelde, Johan Kuiper,
Anton J van Zonneveld,
Steven E Shoelson,
Peter J Voshol,
Johannes A Romijn,
Louis M Havekes,
Jouke T Tamsma,
Patrick C N Rensen,
Pieter S Hiemstra,
Jimmy F P Berbée
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ABSTRACT: The liver is the key organ involved in systemic inflammation, but the relation between hepatic inflammation and atherogenesis is poorly understood. Since nuclear factor-κB (NF-κB) is a central regulator of inflammatory processes, we hypothesized that chronically enhanced hepatic NF-κB activation, through hepatocyte-specific expression of IκB kinase-β (IKKβ) (LIKK), will aggravate atherosclerosis development in APOE*3-Leiden (E3L) mice.
E3L.LIKK and E3L control littermates were fed a Western-type diet for 24 weeks. E3L.LIKK mice showed a 2.3-fold increased atherosclerotic lesion area and more advanced atherosclerosis in the aortic root with less segments without atherosclerotic lesions (11% vs. 42%), and more segments with mild (63% vs. 44%) and severe (26% vs. 14%) lesions. Expression of LIKK did not affect basal levels of inflammatory parameters, but plasma cytokine levels tended to be higher in E3L.LIKK mice after lipopolysaccharide (LPS) administration. E3L.LIKK mice showed transiently increased plasma cholesterol levels, confined to (V)LDL. This transient character resulted in a mild (+17%) increased cumulative plasma cholesterol exposure.
We conclude that selective activation of NF-κB in hepatocytes considerably promotes atherosclerosis development which is (at least partly) explained by an increased sensitivity to proinflammatory triggers and transiently increased plasma cholesterol levels.
Atherosclerosis 07/2011; 220(2):362-8. · 3.79 Impact Factor
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Saskia C A de Jager,
Beatriz Bermúdez,
Ilze Bot,
Rory R Koenen,
Martine Bot,
Annemieke Kavelaars,
Vivian de Waard,
Cobi J Heijnen,
Francisco J G Muriana,
Christian Weber,
Theo J C van Berkel, Johan Kuiper,
Se-Jin Lee,
Rocio Abia,
Erik A L Biessen
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ABSTRACT: Growth differentiation factor (GDF) 15 is a member of the transforming growth factor β (TGF-β) superfamily, which operates in acute phase responses through a currently unknown receptor. Elevated GDF-15 serum levels were recently identified as a risk factor for acute coronary syndromes. We show that GDF-15 expression is up-regulated as disease progresses in murine atherosclerosis and primarily colocalizes with plaque macrophages. Hematopoietic GDF-15 deficiency in low density lipoprotein receptor(-/-) mice led to impaired initial lesion formation and increased collagen in later lesions. Although lesion burden in GDF-15(-/-) chimeras was unaltered, plaques had reduced macrophage infiltrates and decreased necrotic core formation, all features of improved plaque stability. In vitro studies pointed to a TGFβRII-dependent regulatory role of GDF-15 in cell death regulation. Importantly, GDF-15(-/-) macrophages displayed reduced CCR2 expression, whereas GDF-15 promoted macrophage chemotaxis in a strictly CCR2- and TGFβRII-dependent manner, a phenomenon which was not observed in G protein-coupled receptor kinase 2(+/-) macrophages. In conclusion, GDF-15 deletion has a beneficial effect both in early and later atherosclerosis by inhibition of CCR2-mediated chemotaxis and by modulating cell death. Our study is the first to identify GDF-15 as an acute phase modifier of CCR2/TGFβRII-dependent inflammatory responses to vascular injury.
Journal of Experimental Medicine 02/2011; 208(2):217-25. · 13.85 Impact Factor
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ABSTRACT: Interleukin 15 (IL-15) is a pro-inflammatory cytokine involved in inflammatory diseases and IL-15 is expressed in atherosclerotic plaques.
To establish the role of IL-15 in atherosclerosis we studied the effect of IL-15 on atherosclerosis associated cells in vitro and in vivo by neutralizing IL-15 using a DNA vaccination strategy.
Upon feeding a Western type diet LDLr(-/-) mice do express higher levels of IL-15 within the spleen and the number of IL-15 expressing cells among blood leukocytes and spleen cells is increased. Addition of IL-15 to macrophages induces the expression TNF-α and CCL-2. After the mice were vaccinated against IL-15, we observe a reduction in plaque size of 75% plaque. Unexpectedly, the relative number of macrophages within the plaque was 2-fold higher in IL-15 vaccinated mice than in control mice. Vaccination against IL-15 leads to an increased cytotoxicity against IL-15 overexpressing target cells, resulting in a reduction in IL-15 expressing cells and macrophages in blood and spleen and a decreased CD4/CD8 ratio.
Hypercholesterolemia leads to upregulation of IL-15 within spleen and blood. DNA vaccination against IL-15 does markedly reduces atherosclerotic lesion size, but does not promote lesion stability.
Vaccine 01/2011; 29(5):976-83. · 3.77 Impact Factor
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Suzanne J A Korporaal,
Illiana Meurs,
Arnaud D Hauer,
Reeni B Hildebrand,
Menno Hoekstra,
Hugo Ten Cate,
Domenico Praticò,
Jan-Willem N Akkerman,
Theo J C Van Berkel, Johan Kuiper,
Miranda Van Eck
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ABSTRACT: Scavenger receptor BI (SR-BI) is a cell surface receptor that promotes the selective uptake of cholesteryl esters from high-density lipoprotein (HDL) by the liver. In mice, SR-BI deficiency results in increased plasma HDL cholesterol levels and enhanced susceptibility to atherosclerosis. The aim of this study was to investigate the role of SR-BI deficiency on platelet function.
SR-BI-deficient mice were thrombocytopenic, and their platelets were abnormally large, probably because of an increased cholesterol content. The FeCl(3) acute injury model to study arterial thrombosis susceptibility showed that SR-BI wild-type mice developed total arterial occlusion after 24±2 minutes. In SR-BI-deficient mice, however, the time to occlusion was reduced to 13±1 minutes (P=0.02). Correspondingly, in SR-BI-deficient mice, platelets circulated in an activated state and showed increased adherence to immobilized fibrinogen. In contrast, platelet-specific disruption of SR-BI by bone marrow transplantation in wild-type mice did not alter plasma cholesterol levels or affect platelet count, size, cholesterol content, or reactivity, suggesting that changes in plasma cholesterol levels were responsible for the altered responsiveness of platelets in SR-BI-deficient mice.
The function of SR-BI in HDL cholesterol homeostasis and prevention of atherosclerosis is indirectly also essential for maintaining normal platelet function and prevention of thrombosis.
Arteriosclerosis Thrombosis and Vascular Biology 11/2010; 31(1):34-42. · 6.37 Impact Factor
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Bart Lammers,
Prakash G Chandak,
Elma Aflaki,
Gijs H M Van Puijvelde,
Branislav Radovic,
Reeni B Hildebrand,
Illiana Meurs,
Ruud Out, Johan Kuiper,
Theo J C Van Berkel,
Dagmar Kolb,
Guenter Haemmerle,
Rudolf Zechner,
Sanja Levak-Frank,
Miranda Van Eck,
Dagmar Kratky
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ABSTRACT: The consequences of macrophage triglyceride (TG) accumulation on atherosclerosis have not been studied in detail so far. Adipose triglyceride lipase (ATGL) is the rate-limiting enzyme for the initial step in TG hydrolysis. Because ATGL knockout (KO) mice exhibit massive TG accumulation in macrophages, we used ATGL KO mice to study the effects of macrophage TG accumulation on atherogenesis.
Low-density lipoprotein receptor (LDLr) KO mice were transplanted with bone marrow from ATGL KO (ATGL KO→LDLr KO) or wild-type (WT→LDLr KO) mice and challenged with a Western-type diet for 9 weeks. Despite TG accumulation in ATGL KO macrophages, atherosclerosis in ATGL KO→LDLr KO mice was 43% reduced associated with decreased plasma monocyte chemoattractant protein-1 (MCP-1) and macrophage interleukin-6 concentrations. This coincided with a reduced amount of macrophages, possibly because of a 39% increase in intraplaque apoptosis and a decreased migratory capacity of ATGL KO macrophages. The reduced number of white blood cells might be due to a 36% decreased Lin(-)Sca-1(+)cKit(+) hematopoietic stem cell population.
We conclude that the attenuation of atherogenesis in ATGL KO→LDLr KO mice is due to decreased infiltration of less inflammatory macrophages into the arterial wall and increased macrophage apoptosis.
Arteriosclerosis Thrombosis and Vascular Biology 10/2010; 31(1):67-73. · 6.37 Impact Factor
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ABSTRACT: MicroRNAs are being used in the oncology field to characterize tumors and predict the survival of cancer patients. Here, we explored the potential of microRNAs as biomarkers for coronary artery disease (CAD) and acute coronary syndromes.
Using real-time PCR-based profiling, we determined the microRNA signature of peripheral blood mononuclear cells (PBMCs) from stable and unstable CAD patients and unaffected controls. 129 of 157 microRNAs measured were expressed by PBMCs and low variability between separate PBMC pools was observed. The presence of CAD in general coincided with a marked 5-fold increase (P<0.001) in the relative expression level of miR-135a, while the expression of miR-147 was 4-fold decreased (P<0.05) in PBMCs from CAD patients as compared to controls, resulting in a 19-fold higher miR-135a/miR-147 ratio (P<0.001) in CAD. MicroRNA/target gene/biological function linkage analysis suggested that the change in PBMC microRNA signature in CAD patients is probably associated with a change in intracellular cadherin/Wnt signaling. Interestingly, unstable angina pectoris patients could be discriminated from stable patients based upon their relatively high expression level of a cluster of three microRNAs including miR-134, miR-198, and miR-370, suggesting that the microRNA signatures can be used to identify patients at risk for acute coronary syndromes.
The present study is the first to show that microRNA signatures can possibly be utilized to identify patients exhibiting atherosclerotic CAD in general and those at risk for acute coronary syndromes. Our findings highlight the importance of microRNAs signatures as novel tool to predict clinical disease outcomes.
Biochemical and Biophysical Research Communications 03/2010; 394(3):792-7. · 2.48 Impact Factor
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ABSTRACT: Recent studies have suggested that variations in PNPLA3 are associated with non-alcoholic fatty liver disease (NAFLD). To gain insight into the potential function of PNPLA3 in liver, we have determined the effect of metabolic shifts on the hepatic expression profile of PNPLA3 in mice.
PNPLA3 expression in wild-type C57BL/6 and NAFLD-susceptible LDL receptor knockout (LDLR-/-) mice was determined using microarray and real-time PCR analysis.
PNPLA3 expression in livers is 50- to 100-fold lower as compared to (cardiac) muscle and adipose tissue in regular chow diet-fed mice. Feeding a Western-type diet stimulated hepatic relative PNPLA3 expression level 23-fold (p<0.001) both in C57BL/6 mice and LDLR-/- mice, suggesting that PNPLA3 does become an important player in hepatic lipid metabolism under conditions of lipid excess. Subjecting mice to fasting fully reversed the effect of the Western-type diet on hepatic PNPLA3 expression. Under these conditions, the expression level of PNPLA3 in adipose tissue is also decreased 90% (p<0.001). Cellular distribution analysis revealed that PNPLA3 is expressed in hepatocytes but not in liver endothelial and Kupffer cells. Microarray-based gene profiling showed that the expression level of PNPLA3 in hepatocytes is correlated with that of genes associated with the lipogenic pathway such as ME1, SPOT14, and SCD1.
It appears that the NAFLD-related gene PNPLA3 is highly responsive to metabolic changes in hepatocytes within the liver and its relative change in expression level suggests an essential function in lipogenesis.
Journal of Hepatology 11/2009; 52(2):244-51. · 9.26 Impact Factor
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ABSTRACT: Modification of lipoproteins plays an important role in the development of atherosclerosis. Oxidatively modified low-density lipoprotein (oxLDL) has a number of pro-inflammatory effects, whereas immunization with various forms of oxLDL is able to reduce atherosclerosis. The uptake of modified LDL by dendritic cells (DCs) and the presentation of epitopes thereof may form an important step in the immunomodulatory effects of LDL. In this study, we transferred oxLDL-pulsed mature DCs (mDCs) to LDL receptor-null (LDLr(-/-)) mice and examined the effects on atherosclerosis.
Bone marrow-derived DCs were cultured for 10 days in the presence of granulocyte-macrophage colony-stimulating factor. Immature DCs were matured by lipopolysaccharide and pulsed with copper-oxidized LDL. These mDCs were transferred three times to LDLr(-/-) mice before the induction of atherosclerosis by Western-type diet feeding. The transfer of oxLDL-pulsed mDCs resulted in an 87% reduction in carotid artery lesion size (P < 0.001) with a concurrent increase in plaque stability, whereas treatment using mDCs pulsed with the atherosclerosis-irrelevant antigen, ovalbumin, did not influence lesion size or stability. Furthermore, the vaccination procedure resulted in the induction of oxLDL-specific T cells with a reduced Th1 profile and an increase in oxLDL-specific IgG levels, which contributed to a reduction in foam cell formation.
These data indicate that vaccination with oxLDL-pulsed mDCs provides a novel and powerful strategy for the immunomodulation of atherosclerosis.
Cardiovascular research 10/2009; 85(3):622-30. · 5.80 Impact Factor
