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Brian J Bennett,
Thomas Q de Aguiar Vallim,
Zeneng Wang,
Diana M Shih,
Yonghong Meng,
Jill Gregory,
Hooman Allayee,
Richard Lee,
Mark Graham,
Rosanne Crooke,
Peter A Edwards,
Stanley L Hazen,
Aldons J Lusis
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ABSTRACT: Circulating trimethylamine-N-oxide (TMAO) levels are strongly associated with atherosclerosis. We now examine genetic, dietary, and hormonal factors regulating TMAO levels. We demonstrate that two flavin mono-oxygenase family members, FMO1 and FMO3, oxidize trimethylamine (TMA), derived from gut flora metabolism of choline, to TMAO. Further, we show that FMO3 exhibits 10-fold higher specific activity than FMO1. FMO3 overexpression in mice significantly increases plasma TMAO levels while silencing FMO3 decreases TMAO levels. In both humans and mice, hepatic FMO3 expression is reduced in males compared to females. In mice, this reduction in FMO3 expression is due primarily to downregulation by androgens. FMO3 expression is induced by dietary bile acids by a mechanism that involves the farnesoid X receptor (FXR), a bile acid-activated nuclear receptor. Analysis of natural genetic variation among inbred strains of mice indicates that FMO3 and TMAO are significantly correlated, and TMAO levels explain 11% of the variation in atherosclerosis.
Cell metabolism. 01/2013; 17(1):49-60.
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Brian W Parks,
Elizabeth Nam,
Elin Org,
Emrah Kostem,
Frode Norheim,
Simon T Hui,
Calvin Pan,
Mete Civelek,
Christoph D Rau, Brian J Bennett, [......],
Lawrence W Castellani,
Bradley Zinker,
Mark Kirby,
Thomas A Drake,
Christian A Drevon,
Rob Knight,
Peter Gargalovic,
Todd Kirchgessner,
Eleazar Eskin,
Aldons J Lusis
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ABSTRACT: Obesity is a highly heritable disease driven by complex interactions between genetic and environmental factors. Human genome-wide association studies (GWAS) have identified a number of loci contributing to obesity; however, a major limitation of these studies is the inability to assess environmental interactions common to obesity. Using a systems genetics approach, we measured obesity traits, global gene expression, and gut microbiota composition in response to a high-fat/high-sucrose (HF/HS) diet of more than 100 inbred strains of mice. Here we show that HF/HS feeding promotes robust, strain-specific changes in obesity that are not accounted for by food intake and provide evidence for a genetically determined set point for obesity. GWAS analysis identified 11 genome-wide significant loci associated with obesity traits, several of which overlap with loci identified in human studies. We also show strong relationships between genotype and gut microbiota plasticity during HF/HS feeding and identify gut microbial phylotypes associated with obesity.
Cell metabolism. 01/2013; 17(1):141-52.
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ABSTRACT: The osteoblast-lineage consists of cells at various stages of maturation that are essential for skeletal development, growth, and maintenance. Over the past decade, many of the signaling cascades that regulate this lineage have been elucidated; however, little is known of the networks that coordinate, modulate, and transmit these signals. Here, we identify a gene network specific to the osteoblast-lineage through the reconstruction of a bone co-expression network using microarray profiles collected on 96 Hybrid Mouse Diversity Panel (HMDP) inbred strains. Of the 21 modules that comprised the bone network, module 9 (M9) contained genes that were highly correlated with prototypical osteoblast maker genes and were more highly expressed in osteoblasts relative to other bone cells. In addition, the M9 contained many of the key genes that define the osteoblast-lineage, which together suggested that it was specific to this lineage. To use the M9 to identify novel osteoblast genes and highlight its biological relevance, we knocked-down the expression of its two most connected "hub" genes, Maged1 and Pard6g. Their perturbation altered both osteoblast proliferation and differentiation. Furthermore, we demonstrated the mice deficient in Maged1 had decreased bone mineral density (BMD). It was also discovered that a local expression quantitative trait locus (eQTL) regulating the Wnt signaling antagonist Sfrp1 was a key driver of the M9. We also show that the M9 is associated with BMD in the HMDP and is enriched for genes implicated in the regulation of human BMD through genome-wide association studies. In conclusion, we have identified a physiologically relevant gene network and used it to discover novel genes and regulatory mechanisms involved in the function of osteoblast-lineage cells. Our results highlight the power of harnessing natural genetic variation to generate co-expression networks that can be used to gain insight into the function of specific cell-types.
PLoS genetics. 12/2012; 8(12):e1003150.
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Luz D Orozco, Brian J Bennett,
Charles R Farber,
Anatole Ghazalpour,
Calvin Pan,
Nam Che,
Pingzi Wen,
Hong Xiu Qi,
Adonisa Mutukulu,
Nathan Siemers,
Isaac Neuhaus,
Roumyana Yordanova,
Peter Gargalovic,
Matteo Pellegrini,
Todd Kirchgessner,
Aldons J Lusis
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ABSTRACT: Many common diseases have an important inflammatory component mediated in part by macrophages. Here we used a systems genetics strategy to examine the role of common genetic variation in macrophage responses to inflammatory stimuli. We examined genome-wide transcript levels in macrophages from 92 strains of the Hybrid Mouse Diversity Panel. We exposed macrophages to control media, bacterial lipopolysaccharide (LPS), or oxidized phospholipids. We performed association mapping under each condition and identified several thousand expression quantitative trait loci (eQTL), gene-by-environment interactions, and eQTL "hot spots" that specifically control LPS responses. We used siRNA knockdown of candidate genes to validate an eQTL hot spot in chromosome 8 and identified the gene 2310061C15Rik as a regulator of inflammatory responses in macrophages. We have created a public database where the data presented here can be used as a resource for understanding many common inflammatory traits that are modeled in the mouse and for the dissection of regulatory relationships between genes.
Cell. 10/2012; 151(3):658-70.
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Anatole Ghazalpour,
Christoph D Rau,
Charles R Farber, Brian J Bennett,
Luz D Orozco,
Atila van Nas,
Calvin Pan,
Hooman Allayee,
Simon W Beaven,
Mete Civelek, [......],
Desmond J Smith,
Sotirios Tetradis,
Jessica Wang,
Yibin Wang,
James N Weiss,
Todd Kirchgessner,
Peter S Gargalovic,
Eleazar Eskin,
Aldons J Lusis,
Renée C Leboeuf
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ABSTRACT: We have developed an association-based approach using classical inbred strains of mice in which we correct for population structure, which is very extensive in mice, using an efficient mixed-model algorithm. Our approach includes inbred parental strains as well as recombinant inbred strains in order to capture loci with effect sizes typical of complex traits in mice (in the range of 5 % of total trait variance). Over the last few years, we have typed the hybrid mouse diversity panel (HMDP) strains for a variety of clinical traits as well as intermediate phenotypes and have shown that the HMDP has sufficient power to map genes for highly complex traits with resolution that is in most cases less than a megabase. In this essay, we review our experience with the HMDP, describe various ongoing projects, and discuss how the HMDP may fit into the larger picture of common diseases and different approaches.
Mammalian genome : official journal of the International Mammalian Genome Society. 08/2012; 23(9-10):680-92.
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ABSTRACT: The purpose of this study was to fine map previously identified quantitative trait loci affecting atherosclerosis in mice using association analysis.
We recently showed that high-resolution association analysis using common inbred strains of mice is feasible if corrected for population structure. To use this approach for atherosclerosis, which requires a sensitizing mutation, we bred human apolipoprotein B-100 transgenic mice with 22 different inbred strains to produce F1 heterozygotes. Mice carrying the dominant transgene were tested for association with high-density single nucleotide polymorphism maps. Here, we focus on high-resolution mapping of the previously described atherosclerosis 30 locus on chromosome 1. Compared with the previous linkage analysis, association improved the resolution of the atherosclerosis 30 locus by more than an order of magnitude. Using expression quantitative trait locus analysis, we identified one of the genes in the region, desmin, as a strong candidate.
Our high-resolution mapping approach accurately identifies and fine maps known atherosclerosis quantitative trait loci. These results suggest that high-resolution genome-wide association analysis for atherosclerosis is feasible in mice.
Arteriosclerosis, thrombosis, and vascular biology. 06/2012; 32(8):1790-8.
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Zeneng Wang,
Elizabeth Klipfell, Brian J Bennett,
Robert Koeth,
Bruce S Levison,
Brandon Dugar,
Ariel E Feldstein,
Earl B Britt,
Xiaoming Fu,
Yoon-Mi Chung,
Yuping Wu,
Phil Schauer,
Jonathan D Smith,
Hooman Allayee,
W H Wilson Tang,
Joseph A DiDonato,
Aldons J Lusis,
Stanley L Hazen
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ABSTRACT: Metabolomics studies hold promise for the discovery of pathways linked to disease processes. Cardiovascular disease (CVD) represents the leading cause of death and morbidity worldwide. Here we used a metabolomics approach to generate unbiased small-molecule metabolic profiles in plasma that predict risk for CVD. Three metabolites of the dietary lipid phosphatidylcholine--choline, trimethylamine N-oxide (TMAO) and betaine--were identified and then shown to predict risk for CVD in an independent large clinical cohort. Dietary supplementation of mice with choline, TMAO or betaine promoted upregulation of multiple macrophage scavenger receptors linked to atherosclerosis, and supplementation with choline or TMAO promoted atherosclerosis. Studies using germ-free mice confirmed a critical role for dietary choline and gut flora in TMAO production, augmented macrophage cholesterol accumulation and foam cell formation. Suppression of intestinal microflora in atherosclerosis-prone mice inhibited dietary-choline-enhanced atherosclerosis. Genetic variations controlling expression of flavin monooxygenases, an enzymatic source of TMAO, segregated with atherosclerosis in hyperlipidaemic mice. Discovery of a relationship between gut-flora-dependent metabolism of dietary phosphatidylcholine and CVD pathogenesis provides opportunities for the development of new diagnostic tests and therapeutic approaches for atherosclerotic heart disease.
Nature. 04/2011; 472(7341):57-63.
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Charles R Farber, Brian J Bennett,
Luz Orozco,
Wei Zou,
Ana Lira,
Emrah Kostem,
Hyun Min Kang,
Nicholas Furlotte,
Ani Berberyan,
Anatole Ghazalpour,
Jaijam Suwanwela,
Thomas A Drake,
Eleazar Eskin,
Q Tian Wang,
Steven L Teitelbaum,
Aldons J Lusis
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ABSTRACT: Significant advances have been made in the discovery of genes affecting bone mineral density (BMD); however, our understanding of its genetic basis remains incomplete. In the current study, genome-wide association (GWA) and co-expression network analysis were used in the recently described Hybrid Mouse Diversity Panel (HMDP) to identify and functionally characterize novel BMD genes. In the HMDP, a GWA of total body, spinal, and femoral BMD revealed four significant associations (-log10P>5.39) affecting at least one BMD trait on chromosomes (Chrs.) 7, 11, 12, and 17. The associations implicated a total of 163 genes with each association harboring between 14 and 112 genes. This list was reduced to 26 functional candidates by identifying those genes that were regulated by local eQTL in bone or harbored potentially functional non-synonymous (NS) SNPs. This analysis revealed that the most significant BMD SNP on Chr. 12 was a NS SNP in the additional sex combs like-2 (Asxl2) gene that was predicted to be functional. The involvement of Asxl2 in the regulation of bone mass was confirmed by the observation that Asxl2 knockout mice had reduced BMD. To begin to unravel the mechanism through which Asxl2 influenced BMD, a gene co-expression network was created using cortical bone gene expression microarray data from the HMDP strains. Asxl2 was identified as a member of a co-expression module enriched for genes involved in the differentiation of myeloid cells. In bone, osteoclasts are bone-resorbing cells of myeloid origin, suggesting that Asxl2 may play a role in osteoclast differentiation. In agreement, the knockdown of Asxl2 in bone marrow macrophages impaired their ability to form osteoclasts. This study identifies a new regulator of BMD and osteoclastogenesis and highlights the power of GWA and systems genetics in the mouse for dissecting complex genetic traits.
PLoS genetics. 04/2011; 7(4):e1002038.
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ABSTRACT: The bone morphogenetic proteins (BMPs), a family of morphogens, have been implicated as mediators of calcification and inflammation in the vascular wall.
To investigate the effect of altered expression of matrix Gla protein (MGP), an inhibitor of BMP, on vascular disease.
We used MGP transgenic or MGP-deficient mice bred to apolipoprotein E mice, a model of atherosclerosis. MGP overexpression reduced vascular BMP activity, atherosclerotic lesion size, intimal and medial calcification, and inflammation. It also reduced expression of the activin-like kinase receptor 1 and the vascular endothelial growth factor, part of a BMP-activated pathway that regulates angiogenesis and may enhance lesion formation and calcification. Conversely, MGP deficiency increased BMP activity, which may explain the diffuse calcification of vascular medial cells in MGP deficient aortas and the increase in expression of activin-like kinase receptor 1 and vascular endothelial growth factor. Unexpectedly, atherosclerotic lesion formation was decreased in MGP-deficient mice, which may be explained by a dramatic reduction in expression of endothelial adhesion molecules limiting monocyte infiltration of the artery wall.
Our results indicate that BMP signaling is a key regulator of vascular disease, requiring careful control to maintain normal vascular homeostasis.
Circulation research. 08/2010; 107(4):485-94.
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Brian J Bennett,
Charles R Farber,
Luz Orozco,
Hyun Min Kang,
Anatole Ghazalpour,
Nathan Siemers,
Michael Neubauer,
Isaac Neuhaus,
Roumyana Yordanova,
Bo Guan, [......],
Paul Kayne,
Peter Gargalovic,
Todd Kirchgessner,
Calvin Pan,
Lawrence W Castellani,
Emrah Kostem,
Nicholas Furlotte,
Thomas A Drake,
Eleazar Eskin,
Aldons J Lusis
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ABSTRACT: Systems genetics relies on common genetic variants to elucidate biologic networks contributing to complex disease-related phenotypes. Mice are ideal model organisms for such approaches, but linkage analysis has been only modestly successful due to low mapping resolution. Association analysis in mice has the potential of much better resolution, but it is confounded by population structure and inadequate power to map traits that explain less than 10% of the variance, typical of mouse quantitative trait loci (QTL). We report a novel strategy for association mapping that combines classic inbred strains for mapping resolution and recombinant inbred strains for mapping power. Using a mixed model algorithm to correct for population structure, we validate the approach by mapping over 2500 cis-expression QTL with a resolution an order of magnitude narrower than traditional QTL analysis. We also report the fine mapping of metabolic traits such as plasma lipids. This resource, termed the Hybrid Mouse Diversity Panel, makes possible the integration of multiple data sets and should prove useful for systems-based approaches to complex traits and studies of gene-by-environment interactions.
Genome research. 02/2010; 20(2):281-90.
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ABSTRACT: We sought to determine the genetic factors contributing to atherosclerotic plaque size and cellular composition in the innominate artery, a murine model of advanced atherosclerosis.
We examined genetic contributions to innominate atherosclerotic plaque size and cellular composition in an intercross between C57BL/6J.Apoe(-/-), a strain susceptible to aortic lesions, and C3H/HeJ.Apoe(-/-), a strain resistant to aortic lesions. Surprisingly, total innominate lesion size was similar in the two strains. Genetic analyses identified one novel locus on Chromosome 2 for innominate artery lesion size, a significant locus for fibrous cap thickness on Chromosome 15, and several suggestive loci for cellular composition, all distinct from loci influencing aortic lesions. The Chromosome 2 locus contains a candidate, CD44. We show that CD44 is expressed in the innominate artery and differs strikingly in expression between the parental strains.
Multiple aspects of innominate lesion composition are genetically determined, but in a manner largely independent of the genetic contributions to aortic lesions.
Arteriosclerosis, thrombosis, and vascular biology. 02/2009; 29(3):348-55.
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ABSTRACT: Supplements and diets enriched in antioxidants and soy isoflavones are purported to reduce cardiovascular disease risk. Many experimental studies have demonstrated inhibitory effects of antioxidants and soy isoflavones on the development of fatty streaks in animal models. However, it is still unknown whether antioxidants and isoflavones have comparable inhibitory effects on the progression of advanced stages of atherosclerosis. This is an important question because clinical trials in humans have not supported a cardio-protective role for antioxidants or isoflavones. Thus, we examined the effects of antioxidants and genistein on the progression and composition of established, advanced atherosclerotic lesions in the innominate arteries (IA) of older apolipoprotein E-deficient (apoE(-/-)) mice. Thirty-week-old male apoE(-/-) mice were fed chow with or without genistein (0.27%, w/w) for 6, 12 and 24 weeks. Twenty-week-old male apoE(-/-) mice were fed chow with or without a cocktail of antioxidants (vitamin E 0.2%, w/w; vitamin C 0.05%, w/w; and beta carotene 0.5%, w/w) for 10, 16, and 22 weeks. There were no significant differences in total plasma cholesterol, body weight, average lesion or medial area, or changes in lesion composition with either treatment in comparison to control mice.
Atherosclerosis. 08/2008; 203(1):82-8.
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ABSTRACT: The innominate artery is a predilection site for atherosclerotic lesion formation in hyperlipidemic mice. The lesions at this site in chow-fed apo E-/- mice progress from fatty streaks through stages that include atheroma with large necrotic areas, fibro-fatty nodules containing chondrocyte-like cells and highly calcified, acellular plaques. The advanced lesions in the innominate arteries of the apo E-/- mice exhibit a reproducible frequency of intra-plaque hemorrhage that occurs primarily as a result of fissures through lateral fatty streaks that form adjacent to or on top of the established plaques. However, this plaque disruption is not equivalent to plaque rupture in human lesions where there is rupture of well formed fibrous caps. The plaque disruption in the lesions of the chow-fed apo E-/- mice also do not lead to formation of occlusive thrombi, the predominant marker of plaque rupture in humans. Thus, although the lesions in the innominate arteries of hyperlipidemic mice progress to very advanced stages of the disease, they are not, in our opinion a model in which to study the mechanisms of plaque rupture in humans. The advanced lesions in the innominate arteries of the apo E-/- mice may however be adequate models for studying vascular fibrosis and calcification.
Current drug targets. 04/2008; 9(3):210-6.
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Jesus A Araujo,
Berenice Barajas,
Michael Kleinman,
Xuping Wang, Brian J Bennett,
Ke Wei Gong,
Mohamad Navab,
Jack Harkema,
Constantinos Sioutas,
Aldons J Lusis,
Andre E Nel
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ABSTRACT: Air pollution is associated with significant adverse health effects, including increased cardiovascular morbidity and mortality. Exposure to particulate matter with an aerodynamic diameter of <2.5 microm (PM(2.5)) increases ischemic cardiovascular events and promotes atherosclerosis. Moreover, there is increasing evidence that the smallest pollutant particles pose the greatest danger because of their high content of organic chemicals and prooxidative potential. To test this hypothesis, we compared the proatherogenic effects of ambient particles of <0.18 microm (ultrafine particles) with particles of <2.5 microm in genetically susceptible (apolipoprotein E-deficient) mice. These animals were exposed to concentrated ultrafine particles, concentrated particles of <2.5 microm, or filtered air in a mobile animal facility close to a Los Angeles freeway. Ultrafine particle-exposed mice exhibited significantly larger early atherosclerotic lesions than mice exposed to PM(2.5) or filtered air. Exposure to ultrafine particles also resulted in an inhibition of the antiinflammatory capacity of plasma high-density lipoprotein and greater systemic oxidative stress as evidenced by a significant increase in hepatic malondialdehyde levels and upregulation of Nrf2-regulated antioxidant genes. We conclude that ultrafine particles concentrate the proatherogenic effects of ambient PM and may constitute a significant cardiovascular risk factor.
Circulation research. 03/2008; 102(5):589-96.
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ABSTRACT: Systems biology is an emerging field that attempts to examine multiple elements of a biologic system using techniques such as expression microarrays or proteomics. The goal of systems biology is to detect all the elements of a system and create an interaction network between these so that the system can be explained under specified conditions. In this review we discuss how systems-based approaches are being applied to cardiovascular disease, illustrating concepts, such as the integration of orthogonal datasets, coexpression networks and emergent properties.
Expert review of cardiovascular therapy. 12/2007; 5(6):1095-103.
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ABSTRACT: Recent evidence suggests that dendritic cells may play an important role in atherosclerosis. Based primarily on previous in vitro studies, we hypothesized that granulocyte macrophage colony-stimulating factor (GM-CSF)-deficient mice would have decreased dendritic cells in lesions.
To test this, we characterized gene targeted GM-CSF(-/-) mice crossed to hypercholesterolemic low-density lipoprotein receptor null mice. Our results provide conclusive evidence that GM-CSF is a major regulator of dendritic cell formation in vivo. Aortic lesion sections in GM-CSF(-/-) low-density lipoprotein receptor null animals showed a dramatic 60% decrease in the content of dendritic cells as judged by CD11c staining but no change in the overall content of monocyte-derived cells. The GM-CSF-deficient mice exhibited a significant 20% to 50% decrease in the size of aortic lesions, depending on the location of the lesions. Other prominent changes in GM-CSF(-/-) mice were decreased lesional T cell content, decreased autoantibodies to oxidized lipids, and striking disruptions of the elastin fibers adjacent to the lesion.
Given that GM-CSF is dramatically induced by oxidized lipids in endothelial cells, our data suggest that GM-CSF serves to regulate dendritic cell formation in lesions and that this, in turn, influences inflammation, plaque growth and possibly plaque stability.
Arteriosclerosis, thrombosis, and vascular biology. 04/2007; 27(3):621-7.
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ABSTRACT: Osteoprotegerin (OPG), a member of the tumor necrosis factor (TNF) superfamily of proteins, plays an important role in bone remodeling and is expressed in both mouse and human atherosclerotic lesions. The current study was designed to assess whether OPG plays a role in the progression and calcification of advanced atherosclerotic lesions in apoE(-/-) mice.
Atherosclerotic lesion area and composition and aortic calcium content were examined in mice deficient in both OPG and apolipoprotein E (OPG(-/-).apoE(-/-) mice) at 20, 40, and 60 weeks of age. Littermate OPG(+/+).apoE(-/-) mice were used as controls. The average cross-sectional area of lesions in the innominate arteries was increased in OPG(-/-).apoE(-/-) mice at 40 and 60 weeks of age. The increase in lesion area was coupled with a reduced cellularity and an increase in connective tissue including laminated layers of elastin. Sixty-week-old OPG(-/-).apoE(-/-) mice also had an increase in the area of calcification of the lesions. There were no differences in markers of plaque stability. In vitro, OPG induced matrix metalloproteinase-9 (MMP-9) activity in macrophages and smooth muscle cells and acted as a survival factor for serum-deprived smooth muscle cells.
OPG inhibits advanced plaque progression by preventing an increase in lesion size and lesion calcification. OPG may act as a survival factor and may modulate MMP9 production in vascular cells.
Arteriosclerosis, thrombosis, and vascular biology. 10/2006; 26(9):2117-24.
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ABSTRACT: Advanced atherosclerotic lesions in the innominate arteries of chow-fed apolipoprotein E-deficient mice become highly calcified with 100% frequency by 75 weeks of age. The time course, cell types, and mechanism(s) associated with calcification were investigated.
The deposition of hydroxyapatite is preceded by the formation of fibro-fatty nodules that are populated by cells that morphologically resemble chondrocytes. These cells are spatially associated with small deposits of hydroxyapatite in animals between 45 and 60 weeks of age. Immunocytochemical analyses with antibodies recognizing known chondrocyte proteins show that these cells express the same proteins as chondrocytes within developing bone. Histological and electron microscopic analyses of lesions from animals between 45 and 60 weeks of age show that the chondrocyte-like cells are surrounded by dense connective tissue that stains positive for type II collagen. Nanocrystals of hydroxyapatite can be seen within matrix vesicles derived from the chondrocyte-like cells. In mice between 75 and 104 weeks of age, the lesions have significantly reduced cellularity and contain large calcium deposits. The few remaining chondrocyte-like cells are located adjacent to or within the large areas of calcification.
Calcification of advanced lesions in chow-fed apolipoprotein E-deficient mice occurs reproducibly in mice between 45 and 75 weeks of age. The deposition of hydroxyapatite is mediated by chondrocytes, which suggests that the mechanism of calcification may in part recapitulate the process of endochondral bone formation.
Arteriosclerosis, thrombosis, and vascular biology. 08/2005; 25(7):1420-5.
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ABSTRACT: Inflammation contributes to atherosclerotic plaque initiation and progression. Recent studies suggest that anti-inflammatory drugs such as cyclooxygenase-2 (Cox-2) inhibitors have anti-atherogenic effects. The current study was designed to investigate whether administration of a Cox-2 inhibitor to older apolipoprotein E deficient (apo E-/-) mice with established lesions alters the composition and increases the stability of the lesions.
The Cox-2 inhibitor Celecoxib was administered in chow to 26-week-old, male, apo E-/- mice exhibiting advanced, unstable atherosclerotic lesions within the innominate/brachiocephalic artery. Mice administered Celecoxib had no significant changes in serum cholesterol or the average cross sectional area of atherosclerotic lesion in the innominate artery after 15 weeks of treatment in comparison to non-treated control mice. Histological analyses of sections of the innominate artery demonstrated no significant changes in the frequency of markers of advanced and unstable atherosclerotic plaques, including intra-plaque hemorrhage, vascular calcification, thinning of the fibrous cap, size of the necrotic core and macrophage content. There were also no significant differences in the content of Cox-2 within the lesions. Quantitative real time polymerase chain reaction with mRNA isolated from the aorta of each mouse revealed no significant changes in the expression of tissue factor and inducible nitric oxide synthase. However, mRNA levels for MCP-1 were increased fivefold following 15 weeks of treatment with Celecoxib in comparison to non-treated control mice.
These data suggest that Celecoxib has no effect on the composition of advanced atherosclerotic lesions in older apo E-/- mice.
Cardiovascular research. 11/2003; 60(1):198-204.
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Brian J Bennett
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ABSTRACT: Thesis (Ph. D.)--University of Washington, 2006. Objective. The development of advanced atherosclerotic lesions is a common pathology underlying most cardiovascular deaths. Calcification of advanced atherosclerotic lesions in humans and mice is common but the time course, cell types and mechanism(s) associated with calcification are not well understood. The ApoE-/- mouse is commonly used in atherosclerosis research and may be a promising model to study atherosclerosis associated vascular calcification. I along with several collaborators characterized the calcification of advanced atherosclerotic lesions in ApoE-/- mice. This model then was used to investigate the effect of several potential mediators of vascular calcification. The effect of the isoflavone genistein on vascular calcification was assessed using a classic feeding study approach. Using intercrosses of genetically engineered mice, the role of several bone regulatory proteins, osteoprotegerin, osteopontin and matrix-gla protein, was assessed.Results. Calcification of advanced atherosclerotic lesions in ApoE-/- mice is preceded by the formation of fibro-fatty nodules that are populated by cells that morphologically resemble chondrocytes. These cells are temporally and spatially associated deposits of hydroxyapatite and express the same proteins as chondrocytes within developing bone.A diet enriched with genistein reduces aortic calcium content and elevated circulating OPG. Generation of OPG-/-.apoE-/- mice indicates that OPG has a role in modulating plaque size and calcification. Because OPG-/-.ApoE-/- mice had increased lesion area and aortic calcium content. Analysis of lesion morphology indicates that OPG may act as a survival factor within the lesion.Studies of mgp indicated that mgp inactivation increases lesion size and results in a dramatic change in lesion composition. Mgp-/-.ApoE-/- have increased chondroplastic conversion and plaque calcification at 18 weeks of age when ApoE-/- controls have less complicated and smaller fatty streaks forming. Unfortunately, there was no effect of OPN on atherosclerosis or calcification of the atherosclerotic plaques. However, there was an indication that OPN may modulate the chondroplastic conversion and calcification of the media underlying the lesion.Conclusions. These results indicate that the ApoE-/- mouse is a viable model for studying atherosclerosis associated vascular calcification. Both diet and genetic approaches are able to alter vascular calcification in this model.
