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author:("Wang, jumping")
1.  Testing the iron hypothesis in a mouse model of atherosclerosis 
Cell reports  2013;5(5):10.1016/j.celrep.2013.11.009.
Hepcidin, the iron-regulatory hormone and acute phase reactant, is proposed to contribute to the pathogenesis of atherosclerosis by promoting iron accumulation in plaque macrophages, leading to increased oxidative stress and inflammation in the plaque (the “iron hypothesis”). Hepcidin and iron may thus represent modifiable risk factors in atherosclerosis. We measured hepcidin expression in Apoe−/− mice with varying diets and ages. To assess the role of macrophage iron in atherosclerosis, we generated Apoe−/− mice with macrophage-specific iron accumulation by introducing the ferroportin ffe mutation. Macrophage iron loading was also enhanced by intravenous iron injection. Contrary to the iron hypothesis, we found that hepatic hepcidin expression was not increased at any stage of the atherosclerosis progression in Apoe−/− or Apoe/ffe mice and the atherosclerotic plaque size was not increased in mice with elevated macrophage iron. Our results strongly argue against any significant role of macrophage iron in atherosclerosis progression in mice.
PMCID: PMC3880128  PMID: 24316081
2.  A Two-Stage Approach for Medical Supplies Intermodal Transportation in Large-Scale Disaster Responses 
We present a two-stage approach for the “helicopters and vehicles” intermodal transportation of medical supplies in large-scale disaster responses. In the first stage, a fuzzy-based method and its heuristic algorithm are developed to select the locations of temporary distribution centers (TDCs) and assign medial aid points (MAPs) to each TDC. In the second stage, an integer-programming model is developed to determine the delivery routes. Numerical experiments verified the effectiveness of the approach, and observed several findings: (i) More TDCs often increase the efficiency and utility of medical supplies; (ii) It is not definitely true that vehicles should load more and more medical supplies in emergency responses; (iii) The more contrasting the traveling speeds of helicopters and vehicles are, the more advantageous the intermodal transportation is.
PMCID: PMC4245601  PMID: 25350005
large-scale disasters; medical supplies; intermodal transportation
3.  Deficiency of CCAAT/Enhancer Binding Protein-Epsilon Reduces Atherosclerotic Lesions in LDLR−/− Mice 
PLoS ONE  2014;9(1):e85341.
The CCAAT/enhancer binding proteins (C/EBPs) are transcription factors involved in hematopoietic cell development and induction of several inflammatory mediators. C/EBPε is expressed only in myeloid cells including monocytes/macrophages. Atherosclerosis is an inflammatory disorder of the vascular wall and circulating immune cells such as monocytes/macrophages. Mice deficient in the low density lipoprotein (LDL) receptor (Ldlr−/−) fed on a high cholesterol diet (HCD) show elevated blood cholesterol levels and are widely used as models to study human atherosclerosis. In this study, we generated Ldlr and Cebpe double-knockout (llee) mice and compared their atherogenic phenotypes to Ldlr single deficient (llEE) mice after HCD. Macrophages from llee mice have reduced lipid uptake by foam cells and impaired phagokinetic motility in vitro compared to macrophages from llEE mice. Also, compared to llEE mice, llee mice have alterations of lipid metabolism, and reduced atheroma and obesity, particularly the males. Peritoneal macrophages of llee male mice have reduced mRNA expression of FABP4, a fatty acid binding protein implicated in atherosclerosis. Overall, our study suggests that the myeloid specific factor C/EBPε is involved in systemic lipid metabolism and that silencing of C/EBPε could decrease the development of atherosclerosis.
PMCID: PMC3904867  PMID: 24489659
4.  Resveratrol Inhibits the Growth of Gastric Cancer by Inducing G1 Phase Arrest and Senescence in a Sirt1-Dependent Manner 
PLoS ONE  2013;8(11):e70627.
Resveratrol, a naturally occurring polyphenolic compound, has been reported to exert anticancer activity by affecting diverse molecular targets. In this study, we examined the effects and the underlying mechanisms of resveratrol on gastric cancer. We found that resveratrol inhibited the proliferation of gastric cancer cells in a dose-dependent manner. At the concentration of 25 and 50 µM, resveratrol inhibited the cell viability and diminished the clonogenic potential of gastric cancer cells. Resveratrol treatment arrested gastric cancer cells in the G1 phase and led to senescence instead of apoptosis. Regulators of the cell cycle and senescence pathways, including cyclin D1, cyclin-dependent kinase (CDK4 and 6), p21 and p16, were dysregulated by resveratrol treatment. The inhibitory effects of resveratrol on gastric cancer were also verified in vivo using a nude mice xenograft model. Resveratrol (40 mg/kg/d) exerted inhibitory activities on gastric cancer development and significantly decreased the fractions of Ki67-positive cells in the tumor specimens from the nude mice. After resveratrol treatment, the induction of senescence and the changes in the expression of the regulators involved in the cell cycle and senescence pathways were similar to what we observed in vitro. However, the depletion of Sirtuin (Sirt)1 reversed the above-described effects of resveratrol both in vitro and in vivo. Our data suggest that resveratrol inhibits gastric cancer in a Sirt1-dependent manner and provide detailed evidence for the possibility of applying resveratrol in gastric cancer prevention and therapy.
PMCID: PMC3836800  PMID: 24278101
5.  The effect of 9p21.3 coronary artery disease locus neighboring genes on atherosclerosis in mice 
Circulation  2012;126(15):1896-1906.
The human 9p21.3 chromosome locus has been shown to be an independent risk factor for atherosclerosis in multiple large scale genome-wide association studies, but the underlying mechanism remains unknown. We set out to investigate the potential role of the 9p21.3 locus neighboring genes, including Mtap, the two isoforms of Cdkn2a, p16Ink4a and p19Arf, and Cdkn2b in atherosclerosis using knockout mice models.
Methods and Results
Gene targeted mice for neighboring genes, including Mtap, Cdkn2a, p19Arf, and Cdkn2b, were each bred to mice carrying the human APO*E3 Leiden transgene which sensitizes the mice for atherosclerotic lesions through elevated plasma cholesterol. We found that the mice heterozygous for Mtap developed larger lesion compared to wild-type mice (49623±21650 vs. 18899±9604 μm2/section (Mean±SD); p=0.01), with similar morphology as wild type mice. The Mtap heterozygous mice demonstrated changes in metabolic and methylation profiles and CD4+ cell counts. The Cdkn2a knockout mice had smaller lesions compared to wild-type and heterozygous mice and there were no significant differences in lesion size in p19Arf and Cdkn2b mutants as compared to wild type. We observed extensive, tissue-specific compensatory regulation of the Cdkn2a and Cdkn2b genes among the various knockout mice, making the effects on atherosclerosis difficult to interpret.
Mtap plays a protective role against atherosclerosis, whereas Cdkn2a appears to be modestly proatherogenic. However, no relation was found between the 9p21 genotype and the transcription of 9p21 neighboring genes in primary human aortic vascular cells in vitro. There is extensive compensatory regulation in the highly conserved 9p21 orthologous region in mice.
PMCID: PMC3608429  PMID: 22952318
Atherosclerosis; 9p21 risk locus; Gene targeted mice; Methylthioadenosine Phosphorylase
6.  A peptide-mediated targeting gene delivery system for malignant glioma cells 
Glioblastoma multiforme (GBM) is the most common and malignant glioma. Although there has been considerable progress in treatment strategies, the prognosis of many patients with GBM remains poor. In this work, polyethylenimine (PEI) and the VTWTPQAWFQWV (VTW) peptide were modified and synthesized into GBM-targeting nanoparticles. The transfection efficiency of U-87 (human glioblastoma) cells was evaluated using fluorescence microscopy and flow cytometry. Cell internalization was investigated to verify the nanoparticle delivery into the cytoplasm. Results showed that the methods of polymer conjugation and the amount of VTW peptide were important factors to polymer synthesis and transfection. The PEI-VTW20 nanoparticles increased the transfection efficiency significantly. This report describes the use of VTW peptide-based PEI nanoparticles for intracellular gene delivery in a GBM cell-specific manner.
PMCID: PMC3790891  PMID: 24101872
glioblastoma; polyethylenimine; nanoparticles; drug-delivery systems; gene transfer techniques
7.  High-Resolution Association Mapping of Atherosclerosis Loci in Mice 
To fine map previously identified quantitative trait loci (QTL) affecting atherosclerosis in mice using association analysis.
Methods and Results
We recently showed that high-resolution association analysis using common inbred strains of mice is feasible if corrected for population structure. To utilize this approach for atherosclerosis, which requires a sensitizing mutation, we bred human apoB100 transgenic mice with 22 different inbred strains to produce F1 heterozygotes. Mice carrying the dominant transgene were tested for association with high-density SNP maps. Here we focus on high-resolution mapping of the previously described Ath30 locus on Chr 1. As compared to the previous linkage analysis, association improved the resolution of the Ath30 locus by more than an order of magnitude. Using expression quantitative trait locus analysis, we identified one of the genes in the region, Des, as a strong candidate.
Our high-resolution mapping approach accurately identifies and fine maps known atherosclerosis QTL. These results suggest that high-resolution genome-wide association analysis for atherosclerosis is feasible in mice.
PMCID: PMC3519423  PMID: 22723443
8.  Substance P participates in immune-mediated hepatic injury induced by concanavalin A in mice and stimulates cytokine synthesis in Kupffer cells 
Studies have indicated that the immune system plays a pivotal role in hepatitis. Substance P (SP) has been shown to modulate the immune response. In order to investigate the role of SP in liver injury and to determine whether it leads to pro-inflammatory signaling, we established a mouse model of hepatic injury induced by concanavalin A (ConA). We also exposed mouse Kupffer cells (KCs) to SP in vitro. Cytokine and SP levels in liver homogenates were detected using enzyme-linked immunosorbent assay (ELISA) and the protective effects of L-703,606 were evaluated through serological and histological assessments. Neurokinin-1 receptor (NK-1R) expression was evaluated by immunofluorescence and quantitative polymerase chain reaction (PCR). The levels of SP, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were significantly increased in the ConA-treated mice and the levels of ALT and AST were markedly reduced by L-703,606-pretreatment. Liver injury was significantly reduced by treatment with L-703,606. The mouse KCs expressed NK-1R and SP increased NK-1R mRNA expression. Furthermore, NK-1R blockade eliminated the effect of SP on NK-1R mRNA expression. The cytokine levels exhibited a substantial increase in the SP-pretreated KCs compared with the KCs that were cultured in control medium. The inter-leukin (IL)-6 and tumor necrosis factor (TNF)-α levels in the L-703,606-pretreated KCs were significantly lower compared with those in the SP-pretreated KCs. Our study suggests that neurogenic inflammation induced by SP plays an important role in hepatitis. Mouse KCs express NK-1R and SP increases NK-1R mRNA expression. SP enhances IL-6 and TNF-α secretion and an NK-1R antagonist inhibits this secretion.
PMCID: PMC3786810  PMID: 24137208
concanavalin A; liver injury; substance P; neurokinin 1 receptor antagonist; neurogenic inflammation
9.  LXRα is uniquely required for maximal reverse cholesterol transport and atheroprotection in ApoE-deficient mice[S] 
Journal of Lipid Research  2012;53(6):1126-1133.
The liver X receptor (LXR) signaling pathway is an important modulator of atherosclerosis, but the relative importance of the two LXRs in atheroprotection is incompletely understood. We show here that LXRα, the dominant LXR isotype expressed in liver, plays a particularly important role in whole-body sterol homeostasis. In the context of the ApoE−/− background, deletion of LXRα, but not LXRβ, led to prominent increases in atherosclerosis and peripheral cholesterol accumulation. However, combined loss of LXRα and LXRβ on the ApoE−/− background led to an even more severe cholesterol accumulation phenotype compared to LXRα−/−ApoE−/− mice, indicating that LXRβ does contribute to reverse cholesterol transport (RCT) but that this contribution is quantitatively less important than that of LXRα. Unexpectedly, macrophages did not appear to underlie the differential phenotype of LXRα−/−ApoE−/− and LXRβ−/−ApoE−/− mice, as in vitro assays revealed no difference in the efficiency of cholesterol efflux from isolated macrophages. By contrast, in vivo assays of RCT using exogenously labeled macrophages revealed a marked defect in fecal sterol efflux in LXRα−/−ApoE−/− mice. Mechanistically, this defect was linked to a specific requirement for LXRα−/− in the expression of hepatic LXR target genes involved in sterol transport and metabolism. These studies reveal a previously unrecognized requirement for hepatic LXRα for optimal reverse cholesterol transport in mice.
PMCID: PMC3351819  PMID: 22454476
atherosclerosis; nuclear receptor; cholesterol metabolism; apoliporotein
10.  NF-E2–Related Factor 2 Promotes Atherosclerosis by Effects on Plasma Lipoproteins and Cholesterol Transport That Overshadow Antioxidant Protection 
To test the hypothesis that NF-E2–related factor 2 (Nrf2) expression plays an antiatherogenic role by its vascular antioxidant and anti-inflammatory properties.
Methods and Results
Nrf2 is an important transcription factor that regulates the expression of phase 2 detoxifying enzymes and antioxidant genes. Its expression in vascular cells appears to be an important factor in the protection against vascular oxidative stress and inflammation. We developed Nrf2 heterozygous (HET) and homozygous knockout (KO) mice on an apolipoprotein (apo) E–null background by sequential breeding, resulting in Nrf2−/−, apoE−/− (KO), Nrf2−/+, apoE−/− (HET) and Nrf2+/+, and apoE−/− wild-type littermates. KO mice exhibited decreased levels of antioxidant genes with evidence of increased reactive oxygen species generation compared with wild-type controls. Surprisingly, KO males exhibited 47% and 53% reductions in the degree of aortic atherosclerosis compared with HET or wild-type littermates, respectively. Decreased atherosclerosis in KO mice correlated with lower plasma total cholesterol in a sex-dependent manner. KO mice also had a decreased hepatic cholesterol content and a lower expression of lipogenic genes, suggesting that hepatic lipogenesis could be reduced. In addition, KO mice exhibited atherosclerotic plaques characterized by a lesser macrophage component and decreased foam cell formation in an in vitro lipid-loading assay. This was associated with a lower rate of cholesterol influx, mediated in part by decreased expression of the scavenger receptor CD36.
Nrf2 expression unexpectedly promotes atherosclerotic lesion formation in a sex-dependent manner, most likely by a combination of systemic metabolic and local vascular effects.
PMCID: PMC3037185  PMID: 20947826
atherosclerosis; cytokines; lipoproteins; reactive oxygen species; foam cell formation; lipogenesis; Nrf2
11.  Inhibition of Bone Morphogenetic Proteins Protects against Atherosclerosis and Vascular Calcification 
Circulation research  2010;107(4):485-494.
The bone morphogenetic proteins (BMP), 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.
Methods and Results
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 (ALK)1 and the vascular endothelial growth factor (VEGF), 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 ALK1 and VEGF. 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.
PMCID: PMC2994650  PMID: 20576934
Bone morphogenetic protein; Matrix Gla protein; Atherosclerosis; Vascular calcification; Inflammation
12.  Pathway of Toll-Like Receptor 7/B Cell Activating Factor/B Cell Activating Factor Receptor Plays a Role in Immune Thrombocytopenia In Vivo 
PLoS ONE  2011;6(7):e22708.
Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by anti-platelet autoantibody-mediated platelet destruction. Antigen-presenting cell (APC) dysfunction is considered to play crucial roles in ITP. However, how APC affects autoreactive B cells in ITP is still unknown. Using a mouse model of immune thrombocytopenia, we demonstrated an increase in levels of TLR7 in splenic mononuclear cells (SMCs). Using both TLR7 agonist and TLR7 silencing lentivirus, we found stimulation of TLR7 decreased platelet counts and increased levels of platelet-associated IgG (PAIgG) in ITP mice, which correlates TLR7 with platelet destruction by autoantibodies. Levels of serum BAFF increased significantly in ITP mice and stimulation of TLR7 promoted secretion of BAFF. Among the three BAFF receptors, only BAFF receptor (BAFF-R) increased in ITP mice. However, activation of TLR7 showed no effect on the expression of BAFF receptors. These findings indicate that upregulation of TLR7 may augment BAFF secretion by APC and through ligation of BAFF-R promote autoreactive B cell survival and thus anti-platelet autoantibody production. The pathway of TLR7/BAFF/BAFF-R provides us with an explanation of how activation of APC affects autoantibody production by B cells in ITP and thus might provide a reasonable therapeutic strategy for ITP.
PMCID: PMC3144916  PMID: 21818370
13.  Impaired Development of Atherosclerosis in Abcg1−/−Apoe−/− Mice; Identification of Specific Oxysterols that both Accumulate in Abcg1−/−Apoe−/− Tissues and Induce Apoptosis 
ABCG1 is highly expressed in macrophages and endothelial cells, two cell types that play important roles in the development of atherosclerosis. We generated Abcg1−/−Apoe−/− mice in order to understand the mechanism and cell types involved in changes in atherosclerosis following loss of ABCG1.
Methods and Results
Abcg1−/−Apoe−/− and Apoe−/− mice, and recipient Apoe−/− mice that had undergone transplantation with bone marrow from Apoe−/− or Abcg1−/−Apoe−/− mice were fed a western diet for 12–16 weeks prior to quantification of atherosclerotic lesions. These studies demonstrated that loss of ABCG1 from all tissues, or from only hematopoietic cells, was associated with significantly smaller lesions that contained increased numbers of TUNEL- and cleaved caspase-3-positive apoptotic Abcg1−/− macrophages. We also identified specific oxysterols that accumulate in the brain and macrophages of the Abcg1−/−Apoe−/− mice. These oxysterols promoted apoptosis and altered the expression of pro-apoptotic genes when added to macrophages in vitro.
Loss of ABCG1 from all tissues or from only hematopoietic cells, results in smaller atherosclerotic lesions populated with increased numbers of apoptotic macrophages, by processes independent of ApoE. Specific oxysterols identified in tissues of Abcg1−/−Apoe−/− mice may be critical as they induce macrophage apoptosis and the expression of pro-apoptotic genes.
PMCID: PMC2881948  PMID: 20299684
ABCG1; apolipoprotein E; atherosclerosis; apoptosis; Bid; Bok; oxysterols
14.  Granulocyte Macrophage Colony-Stimulating Factor Regulates Dendritic Cell Content of Atherosclerotic Lesions 
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.
Methods and Results
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.
PMCID: PMC3014056  PMID: 17158354
atherosclerosis; dendritic cells; elastin; GM-CSF; macrophages
15.  Ambient Particulate Pollutants in the Ultrafine Range Promote Early Atherosclerosis and Systemic Oxidative Stress 
Circulation research  2008;102(5):589-596.
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 μm (PM2.5) 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 μm (ultrafine particles) with particles of <2.5 μm in genetically susceptible (apolipoprotein E–deficient) mice. These animals were exposed to concentrated ultrafine particles, concentrated particles of <2.5 μm, 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 PM2.5 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.
PMCID: PMC3014059  PMID: 18202315
air pollution; ultrafine particles; atherosclerosis; oxidative stress; HDL
16.  Chylomicronemia Elicits Atherosclerosis in Mice 
The risk of atherosclerosis in the setting of chylomicronemia has been a topic of debate. In this study, we examined susceptibility to atherosclerosis in Gpihbp1-deficient mice (Gpihbp1−/−), which manifest severe chylomicronemia as a result of defective lipolysis.
Methods and Results
Gpihbp1−/− mice on a chow diet have plasma triglyceride and cholesterol levels of 2812 ± 209 and 319 ± 27 mg/dl, respectively. Even though nearly all of the lipids were contained in large lipoproteins (50–135 nm), the mice developed progressive aortic atherosclerosis. In other experiments, we found that both Gpihbp1-deficient “apo-B48–only” mice and Gpihbp1-deficient “apo-B100–only” mice manifest severe chylomicronemia. Thus, GPIHBP1 is required for the processing of both apo-B48– and apo-B100–containing lipoproteins.
Chylomicronemia causes atherosclerosis in mice. Also, we found that GPIHBP1 is required for the lipolytic processing of both apo-B48– and apo-B100–containing lipoproteins.
PMCID: PMC2796285  PMID: 19815815
lipoprotein lipase; chylomicronemia; lipolysis; GPIHBP1
17.  Identification and validation of genes affecting aortic lesions in mice 
The Journal of Clinical Investigation  2010;120(7):2414-2422.
Atherosclerosis represents the most significant risk factor for coronary artery disease (CAD), the leading cause of death in developed countries. To better understand the pathogenesis of atherosclerosis, we applied a likeli­hood-based model selection method to infer gene-disease causality relationships for the aortic lesion trait in a segregating mouse population demonstrating a spectrum of susceptibility to developing atherosclerotic lesions. We identified 292 genes that tested causal for aortic lesions from liver and adipose tissues of these mice, and we experimentally validated one of these candidate causal genes, complement component 3a receptor 1 (C3ar1), using a knockout mouse model. We also found that genes identified by this method overlapped with genes progressively regulated in the aortic arches of 2 mouse models of atherosclerosis during atherosclerotic lesion development. By comparing our gene set with findings from public human genome-wide association studies (GWAS) of CAD and related traits, we found that 5 genes identified by our study overlapped with published studies in humans in which they were identified as risk factors for multiple atherosclerosis-related pathologies, including myocardial infarction, serum uric acid levels, mean platelet volume, aortic root size, and heart failure. Candidate causal genes were also found to be enriched with CAD risk polymorphisms identified by the Wellcome Trust Case Control Consortium (WTCCC). Our findings therefore validate the ability of causality testing procedures to provide insights into the mechanisms underlying atherosclerosis development.
PMCID: PMC2898611  PMID: 20577049
18.  Treatment with apolipoprotein A-1 mimetic peptide reduces lupus-like manifestations in a murine lupus model of accelerated atherosclerosis 
The purpose of this study was to evaluate the effects of L-4F, an apolipoprotein A-1 mimetic peptide, alone or with pravastatin, in apoE-/-Fas-/-C57BL/6 mice that spontaneously develop immunoglobulin G (IgG) autoantibodies, glomerulonephritis, osteopenia, and atherosclerotic lesions on a normal chow diet.
Female mice, starting at eight to nine weeks of age, were treated for 27 weeks with 1) pravastatin, 2) L-4F, 3) L-4F plus pravastatin, or 4) vehicle control, followed by disease phenotype assessment.
In preliminary studies, dysfunctional, proinflammatory high-density lipoproteins (piHDL) were decreased six hours after a single L-4F, but not scrambled L-4F, injection in eight- to nine-week old mice. After 35 weeks, L-4F-treated mice, in the absence/presence of pravastatin, had significantly smaller lymph nodes and glomerular tufts (PL, LP < 0.05), lower serum levels of IgG antibodies to double stranded DNA (dsDNA) (PL < 0.05) and oxidized phospholipids (oxPLs) (PL, LP < 0.005), and elevated total and vertebral bone mineral density (PL, LP < 0.01) compared to vehicle controls. Although all treatment groups presented larger aortic root lesions compared to vehicle controls, enlarged atheromas in combination treatment mice had significantly less infiltrated CD68+ macrophages (PLP < 0.01), significantly increased mean α-actin stained area (PLP < 0.05), and significantly lower levels of circulating markers for atherosclerosis progression, CCL19 (PL, LP < 0.0005) and VCAM-1 (PL < 0.0002).
L-4F treatment, alone or with pravastatin, significantly reduced IgG anti-dsDNA and IgG anti-oxPLs, proteinuria, glomerulonephritis, and osteopenia in a murine lupus model of accelerated atherosclerosis. Despite enlarged aortic lesions, increased smooth muscle content, decreased macrophage infiltration, and decreased pro-atherogenic chemokines in L-4F plus pravastatin treated mice suggest protective mechanisms not only on lupus-like disease, but also on potential plaque remodeling in a murine model of systemic lupus erythematosus (SLE) and accelerated atherosclerosis.
PMCID: PMC2911877  PMID: 20482780
19.  Quantitative Trait Locus Mapping and Identification of Zhx2 as a Novel Regulator of Plasma Lipid Metabolism 
We previously mapped a quantitative trait locus on chromosome 15 in mice contributing to high-density lipoprotein cholesterol and triglyceride levels and now report the identification of the underlying gene.
Methods and Results
We first fine-mapped the locus by studying a series of congenic strains derived from the parental strains BALB/cJ and MRL/MpJ. Analysis of gene expression and sequencing followed by transgenic complementation led to the identification of zinc fingers and homeoboxes 2 (Zhx2), a transcription factor previously implicated in the developmental regulation of α-fetoprotein. Reduced expression of the protein in BALB/cJ mice resulted in altered hepatic transcript levels for several genes involved in lipoprotein metabolism. Most notably, the Zhx2 mutation resulted in a failure to suppress expression of lipoprotein lipase, a gene normally silenced in the adult liver, and this was normalized in BALB/cJ mice carrying the Zhx2 transgene.
We identified the gene underlying the chromosome 15 quantitative trait locus, and our results show that Zhx2 functions as a novel developmental regulator of key genes influencing lipoprotein metabolism.
PMCID: PMC2846770  PMID: 20160197
genetics; lipoproteins; atherosclerosis; genes; mapping
20.  Disruption of the Aortic Elastic Lamina and Medial Calcification Share Genetic Determinants in Mice 
Disruption of the elastic lamina, as an early indicator of aneurysm formation, and vascular calcification frequently occur together in atherosclerotic lesions of humans.
Methods and Results
We now report evidence of shared genetic basis for disruption of the elastic lamina (medial disruption) and medial calcification in an F2 mouse intercross between C57BL/6J and C3H/HeJ on a hyperlipidemic apolipoprotein E (ApoE−/−) null background. We identified 3 quantitative trait loci (QTLs) on chromosomes 6, 13, and 18, which are common to both traits, and 2 additional QTLs for medial calcification on chromosomes 3 and 7. Medial disruption, including severe disruptions leading to aneurysm formation, and medial calcification were highly correlated and occurred concomitantly in the cross. The chromosome 18 locus showed a striking male sex-specificity for both traits. To identify candidate genes, we integrated data from microarray analysis, genetic segregation, and clinical traits. The chromosome 7 locus contains the Abcc6 gene, known to mediate myocardial calcification. Using transgenic complementation, we show that Abcc6 also contributes to aortic medial calcification.
Our data indicate that calcification, though possibly contributory, does not always lead to medial disruption and that in addition to aneurysm formation, medial disruption may be the precursor to calcification.
PMCID: PMC2836127  PMID: 20031637
aneurysm vascular calcification; Abcc6; Alox5; genetics; gene expression
21.  Ligand activation of LXRβ reverses atherosclerosis and cellular cholesterol overload in mice lacking LXRα and apoE 
Journal of Clinical Investigation  2007;117(8):2337-2346.
Liver X receptors (LXRs) α and β are transcriptional regulators of cholesterol homeostasis and potential targets for the development of antiatherosclerosis drugs. However, the specific roles of individual LXR isotypes in atherosclerosis and the pharmacological effects of synthetic agonists remain unclear. Previous work has shown that mice lacking LXRα accumulate cholesterol in the liver but not in peripheral tissues. In striking contrast, we demonstrate here that LXRα–/–apoE–/– mice exhibit extreme cholesterol accumulation in peripheral tissues, a dramatic increase in whole-body cholesterol burden, and accelerated atherosclerosis. The phenotype of these mice suggests that the level of LXR pathway activation in macrophages achieved by LXRβ and endogenous ligand is unable to maintain homeostasis in the setting of hypercholesterolemia. Surprisingly, however, a highly efficacious synthetic agonist was able to compensate for the loss of LXRα. Treatment of LXRα–/–apoE–/– mice with synthetic LXR ligand ameliorates the cholesterol overload phenotype and reduces atherosclerosis. These observations indicate that LXRα has an essential role in maintaining peripheral cholesterol homeostasis in the context of hypercholesterolemia and provide in vivo support for drug development strategies targeting LXRβ.
PMCID: PMC1924496  PMID: 17657314
22.  Increased atherosclerosis in myeloperoxidase-deficient mice 
Journal of Clinical Investigation  2001;107(4):419-430.
Myeloperoxidase (MPO), a heme enzyme secreted by activated phagocytes, generates an array of oxidants proposed to play critical roles in host defense and local tissue damage. Both MPO and its reaction products are present in human atherosclerotic plaque, and it has been proposed that MPO oxidatively modifies targets in the artery wall. We have now generated MPO-deficient mice, and show here that neutrophils from homozygous mutants lack peroxidase and chlorination activity in vitro and fail to generate chlorotyrosine or to kill Candida albicans in vivo. To examine the potential role of MPO in atherosclerosis, we subjected LDL receptor–deficient mice to lethal irradiation, repopulated their marrow with MPO-deficient or wild-type cells, and provided them a high-fat, high-cholesterol diet for 14 weeks. White cell counts and plasma lipoprotein profiles were similar between the two groups at sacrifice. Cross-sectional analysis of the aorta indicated that lesions in MPO-deficient mice were about 50% larger than controls. Similar results were obtained in a genetic cross with LDL receptor–deficient mice. In contrast to advanced human atherosclerotic lesions, the chlorotyrosine content of aortic lesions from wild-type as well as MPO-deficient mice was essentially undetectable. These data suggest an unexpected, protective role for MPO-generated reactive intermediates in murine atherosclerosis. They also identify an important distinction between murine and human atherosclerosis with regard to the potential involvement of MPO in protein oxidation.
PMCID: PMC199241  PMID: 11181641

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