BAY x 1005 attenuates atherosclerosis in apoE/LDLR - double knockout mice.

Recently, we have shown that MK-886 - an inhibitor of five lipoxygenase activating protein (FLAP) inhibits atherosclerosis in apolipoprotein E / LDL receptor - double knockout mice. We, therefore, wanted to find out if other FLAP inhibitor - BAYx1005 given at a dose of 1.88 mg per 100 mg of body weight per day during 16 weeks, could also attenuate atherogenesis. In apoE/LDLR - DKO mouse model BAYx1005 inhibited atherogenesis, measured both by "en face" method (23.84 +/- 2.7% vs. 15.16 +/- 1.4%) and "cross-section" method (497236 +/- 31516 microm(2) vs. 278107 +/- 21824 microm(2)). This is the first report that shows the effect of BAYx1005 on atherogenesis in gene-targeted mice.     

ApoE derived from adipose tissue does not suppress atherosclerosis or correct hyperlipidemia in apoE knockout mice

The synthesis of apoE by adipocytes has profound effects on adipose tissue lipid flux and gene expression. Using adipose tissue transplantation from wild-type (WT) to apoE knockout (EKO) mice, we show that adipose tissue also contributes to circulating apoE. Different from circulating apoE produced by bone marrow transplantation (BMT), however, adipose tissue-derived apoE does not correct hyperlipidemia or suppress atherosclerosis. ApoE secreted by macrophages has a more acidic isoform distribution, and it increases binding of reconstituted VLDL particles to hepatocytes and fibroblasts more effectively than apoE secreted by adipocytes. The incremental binding can be entirely accounted for by binding to the LDL receptor. After BMT into EKO hosts, plasma cholesterol and macrophage-derived apoE are largely within IDL/LDL- and HDL-sized particles. After adipose tissue transplantation, most cholesterol and adipocyte apoE remain in VLDL. After BMT, circulating apoE no longer demonstrates predominance of acidic isoforms compared with that circulating after fat transplantation. In conclusion, fat transplantation provides circulating apoE levels similar to those provided by bone marrow transplantation, but it does not suppress hyperlipidemia or atherosclerosis. A potential mechanism contributing to this difference is differential binding to cell surface lipoprotein receptors.     

Inhibition of nuclear factor-kappaB attenuates artherosclerosis in apoE/LDLR - double knockout mice.

Nuclear factor - kappaB (NF-kappaB) is a good therapeutic target for cardiovascular disease and numerous efforts are being made to develop safe NF-kappaB inhibitors. Nowadays many authors address NF-kappaB as a major therapeutic target in atherosclerosis, especially for preventive measures, in the light of two main hypothesis of atherosclerosis: oxidation and inflammation. We hypothesized that ammonium pyrrolidinedithioocarbamate (PDTC) - a well-known inhibitor of NF-kappaB could inhibit the development of atherosclerosis in this experimental model. We used apoE/LDLR - DKO mouse model, which is considered as a one of the best models to study the anti-atherosclerotic effect of drugs. In this model PDTC inhibited atherogenesis, measured both by "en face" method (25,15+/-2,9% vs. 15,63+/-0,6%) and "cross-section" method (565867+/-39764 microm2 vs. 291695+/-30384 microm2). Moreover, PDTC did not change the profile of cholesterol and triglycerides in blood. To our knowledge, this is the first report that shows the effect of PDTC on atherogenesis in gene-targeted apoE/LDLR - double knockout mice.     

apoE/LDLR双基因缺失幼龄小鼠主动脉中动脉粥样硬化相关基因的表达

利用RT-PCR以及实时定量RT-PCR检测11个动脉粥样硬化(atherosclerosis,AS)相关基因在1、2和3月龄的载脂蛋白E(apolipoproteinE,aopE)/低密度脂蛋白受体(low-density lipoprotein receptor,LDLR)双基因缺失(apoE-/-/LDLR-/-)小鼠主动脉中的表达变化,同时应用血生化指标和病理形态学观察AS早期病变特点,探讨apoE和LDLR基因联合缺失引发的血脂代谢紊乱和血管炎症损伤的关系以及AS的炎症反应机制.结果显示,apoE-/-/LDLR-/-小鼠IL-18、TLR2、MCP-1、ICAM-1、VCAM-1、GM-CSF、CD36和ET-1表达在1月龄时较同龄野生型(wild type,WT)小鼠显著上调(P<0.05,P<0.01),PDGF-α和TNF-α表达在2月龄时较同龄WT小鼠显著上调,除ET-1表达在2月龄时以及了LR2、VCAM-1和ICAM-1表达在3月龄时降至WT小鼠水平以外,其余各基因表达随年龄增长继续升高(P<0.05,P<0.01),其中MCP-1表达在2月龄时达到峰值.NF-kB在各年龄段apoE-/-/LDLR-/-小鼠中的表达与同龄WT小鼠相比均无显著差异.各年龄段apoE-/-/LDLR-/-/小鼠血清了C、TG、LDL、HDL、TNF-α、IL-1β和ox-LDL含量均显著高于同龄WT小鼠(P<0.05,P<0.01),并随年龄增长逐渐升高.apoE-/-/LDLR-/-小鼠1月龄时主动脉内膜出现少量的散在的脂质沉积,随着年龄增长病变区域增多,脂质沉积增厚.上述结果提示:apoE和LDLR双基因缺失形成的高脂血症可能通过刺激主动脉中炎症基因时序表达,起始并扩大病变部位的炎症反应,共同促进AS的发生发展.     

Combined serum paraoxonase knockout/apolipoprotein E knockout mice exhibit increased lipoprotein oxidation and atherosclerosis

Serum paraoxonase (PON1), present on high density lipoprotein, may inhibit low density lipoprotein (LDL) oxidation and protect against atherosclerosis. We generated combined PON1 knockout (KO)/apolipoprotein E (apoE) KO and apoE KO control mice to compare atherogenesis and lipoprotein oxidation. Early lesions were examined in 3-month-old mice fed a chow diet, and advanced lesions were examined in 6-month-old mice fed a high fat diet. In both cases, the PON1 KO/apoE KO mice exhibited significantly more atherosclerosis (50-71% increase) than controls. We examined LDL oxidation and clearance in vivo by injecting human LDL into the mice and following its turnover. LDL clearance was faster in the double KO mice as compared with controls. There was a greater rate of accumulation of oxidized phospholipid epitopes and a greater accumulation of LDL-immunoglobulin complexes in the double KO mice than in controls. Furthermore, the amounts of three bioactive oxidized phospholipids were elevated in the endogenous intermediate density lipoprotein/LDL of double KO mice as compared with the controls. Finally, the expression of heme oxygenase-1, peroxisome proliferator-activated receptor gamma, and oxidized LDL receptors were elevated in the livers of double KO mice as compared with the controls. These data demonstrate that PON1 deficiency promotes LDL oxidation and atherogenesis in apoE KO mice.     

Intermedin ameliorates atherosclerosis in apoE null mice by modifying lipid profiles

Intermedin (IMD) is a recently discovered vasodilator peptide. We studied the role of IMD in the pathogenesis of atherosclerosis by investigating the ability of exogenous IMD to alter lipid profiles and ameliorate the development of atherogenic-diet induced atherosclerosis in ApoE−/− mice. Ten of eight-week-old male C57BL/6J mice were as control. Thirty of eight-week-old male ApoE−/− mice were fed with an atherogenic diet for 18 weeks. After feeding atherogenic diet for 12 weeks, the mice were equally and randomly divided into three groups. Normal saline was given in group A and C57BL/6J mice. Intermedin was given by mini osmotic pumps at the dosage of 100 ng/kg/h and 500 ng/kg/h in group B and group C respectively. After the treatment of IMD for 6 weeks, aortic ultrasonography of group C showed that IMD prevented the progression of atherosclerotic lesions and the increase of wall thickness in the aorta. Oil-red-O staining of the entire aorta and the atherosclerotic aortic root section showed 2 folds decrease atherogenic plaque (p < 0.05). Serum lipid profiles were measured, compared with the group A, in group C TC and LDL-C levels were decreased by 86.32% and 89.68%, respectively (both p < 0.05), meanwhile, HDL-C level was significantly increased by 74.82% (p < 0.05). These data indicate that exogenous administration of IMD could prevent the progression of atherosclerotic plaque. The possible underlying mechanisms may relate to the improvement of lipid profiles.     

Proteomic analysis of changes in protein expression in liver mitochondria in apoE knockout mice

The involvement of both apolipoprotein E (apoE) and mitochondria in lipid metabolism is widely recognized, however there is surprisingly scarce data about the putative mitochondrial action(s) of this protein. The aim of the study was to screen the alterations in liver mitochondrial proteome caused by apoE deficiency. We applied 2DE-LC-MS/MS methodology to investigate the changes in liver mitochondrial protein expression in 6-months old apoE(-/-) mice as compared to C57BL/6J controls. ApoE(-/-), but not C57BL/6J mice developed visible atherosclerotic changes in aorta and mild, diffuse steatosis of the liver. Collectively, 18 differentially expressed proteins were identified in mitochondria, related to apoptosis, antioxidant and detoxifying mechanisms of mitochondria, as well as lipid metabolism and transport. In conclusion, differential proteomic approach revealed several lines of proteomic evidence that mitochondrial function in the liver of apoE(-/-) mice could be altered as a result of overlapping of pathological and compensatory changes in expression of proteins.     

Overexpressed lipoprotein lipase protects against atherosclerosis in apolipoprotein E knockout mice.

Lipoprotein lipase (LPL) is known to play a crucial role in lipoprotein metabolism by hydrolyzing triglycerides; however its role in atherogenesis has yet to be determined. We have previously shown that low density lipoprotein receptor knockout mice overexpressing LPL are resistant to diet-induced atherosclerosis due to the suppression of remnant lipoproteins. Plasma lipoproteins and atherosclerosis of apolipoprotein (apo) E knockout mice which overexpress the human LPL transgene (LPL/APOEKO) were compared with those of control apoE knockout mice (APOEKO). On a normal chow diet, LPL/APOEKO mice showed marked suppression of the plasma triglyceride levels compared with APOEKO mice (54 vs. 182 mg/dl), but no significant changes in plasma cholesterol and apoB levels. Non-high density lipoproteins (HDL) from LPL/APOEKO mice had lower triglyceride content, a smaller size, and a more positive charge compared with those from APOEKO mice. Cholesterol, apoA-I, and apoA-IV were increased in HDL. Although both groups developed hypercholesterolemia to a comparable degree in response to an atherogenic diet, the LPL/APOEKO mice developed 2-fold smaller fatty streak lesions in the aortic sinus compared to the APOEKO mice. In conclusion, overproduction of LPL is protective against atherosclerosis even in the absence of apoE.     

脂代谢相关基因在apoE基因缺失幼龄小鼠肝脏中的表达

本文旨在分析脂代谢相关基因在载脂蛋白E(apolipoprotein E,apoE)基因缺失(apoE-/-)幼龄小鼠肝脏中的表达特征及其与血脂紊乱和动脉粥样硬化(atherosclerosis,AS)早期病变的关系.利用半定量RT-PCR和荧光实时定量RT-PCR技术,分析14 d龄、1、2和3月龄apoE-/-小鼠及同龄野生型(wild type,WT)小鼠肝脏脂代谢相关基因的表达,并进行血生化指标及主动脉病理形态学榆测.apo-/-小鼠肝脏中apoAI、apoAIV表达在14d龄时即发生显著变化(P<0.05);在1月龄时apoB10G表达较同龄WT小鼠明显上调(P＜0.05);apoA V表达则在2月龄时较同龄WT小鼠上调(P＜0.05),此时可观察到apoE-/-小鼠主动脉内膜出现AS早期病变;Faf/CD36和Angptl 3表达在3月龄时较同龄WT小鼠上调(P＜0.05);实验中检测的其它基因的mRNA表达与同龄WT小鼠相比无显著性差异.apoE-/-小鼠血清总胆同醇、甘油三酯、低密度脂蛋白胆固醇和高密度脂蛋白胆固醇含量均高于同龄WT小鼠,并随年龄增长而升高.apoE-/-小鼠和同龄WT小鼠血清中apoB100蛋白浓度在14 d龄到3月龄问变化趋势与其在肝脏中mRNA表达及血清中低密度脂蛋白胆崮醇含量变化趋势基本一致.上述部分脂代谢相关基因表达在幼龄小鼠即发生改变,与血脂紊乱以及主动脉AS病变发生发展过程呈正相关,说明其可能在幼龄小鼠脂质代谢紊乱发生过程中起重要作用,从而引起动脉内皮细胞功能改变乃至AS早期病变的发生.     

Cytomegalovirus infection aggravates atherogenesis in apoE knockout mice by both local and systemic immune activation

Since the 1970s, cytomegalovirus (CMV) infection has been associated with atherosclerotic disease. However, the exact contribution of the virus remains uncertain. In this article we describe both a direct and indirect immune-mediated effect of the virus on the disease process. Eight-week-old apolipoprotein E (apoE) knockout mice were infected with mouse CMV (MCMV) or mock injected, and they were sacrificed at 2 and 20 weeks post-injection (p.i.) to study atherosclerosis, vascular wall IFNgamma and TNFalpha expression and MCMV spread. To study plasma IFNgamma and TNFalpha levels, blood was collected at 1, 2, 4 and 6 days p.i. in addition to days of sacrifice. Plasma cytokine levels were increased after MCMV infection at early time points and decreased to mock levels at 2 and 20 weeks p.i. At 2 weeks p.i., more aortic arch samples showed local cytokine expression after MCMV infection. The number of early atherosclerotic lesions and the percentage of mice containing early lesions were increased at 2 weeks p.i., while at 20 weeks p.i., the MCMV-induced effect on atherogenesis was seen on the late lesions. In conclusion, MCMV infection induces a systemic immune response reflecting an indirect effect of MCMV infection on atherosclerosis in addition to a local aortic immune response reflecting a direct effect of the virus on the atherosclerotic process.     

Apolipoprotein C-III deficiency accelerates triglyceride hydrolysis by lipoprotein lipase in wild-type and apoE knockout mice

Previous studies with hypertriglyceridemic APOC3 transgenic mice have suggested that apolipoprotein C-III (apoC-III) may inhibit either the apoE-mediated hepatic uptake of TG-rich lipoproteins and/or the lipoprotein lipase (LPL)-mediated hydrolysis of TG. Accordingly, apoC3 knockout (apoC3(-/-)) mice are hypotriglyceridemic. In the present study, we attempted to elucidate the mechanism(s) underlying these phenomena by intercrossing apoC3(-/-) mice with apoE(-/-) mice to study the effects of apoC-III deficiency against a hyperlipidemic background. Similar to apoE(+/+) apoC3(-/-) mice, apoE(-/-)apoC3(-/-) mice exhibited a marked reduction in VLDL cholesterol and TG, indicating that the mechanism(s) by which apoC-III deficiency exerts its lipid-lowering effect act independent of apoE. On both backgrounds, apoC3(-/-) mice showed normal intestinal lipid absorption and hepatic VLDL TG secretion. However, turnover studies showed that TG-labeled emulsion particles were cleared much more rapidly in apoC3(-/-) mice, whereas the clearance of VLDL apoB, as a marker for whole particle uptake by the liver, was not affected. Furthermore, it was shown that cholesteryl oleate-labeled particles were also cleared faster in apoC3(-/-) mice. Thus the mechanisms underlying the hypolipidemia in apoC3(-/-) mice involve both a more efficient hydrolysis of VLDL TG as well as an enhanced selective clearance of VLDL cholesteryl esters from plasma. In summary, our studies of apoC3(-/-) mice support the concept that apoC-III is an effective inhibitor of VLDL TG hydrolysis and reveal a potential regulating role for apoC-III with respect to the selective uptake of cholesteryl esters.     

Physiological expression of macrophage apoE in the artery wall reduces atherosclerosis in severely hyperlipidemic mice

We have previously reported that the introduction of macrophage apoE into mice lacking both apoE and the LDL receptor (apoE(-)(/-)/LDLR(-)(/-)) through bone marrow transplantation (apoE(+)(/+)/LDLR(-)(/-)-->apoE(-)(/-)/LDLR(-)(/-)) produces progressive accumulation of apoE in plasma without affecting lipid levels. This model provides a tool to study the effects of physiologically regulated amounts of macrophage apoE on atherogenesis in hyperlipidemic animals. Ten-week-old male apoE(-)(/-)/LDLR(-)(/-) mice were transplanted with either apoE(+)(/+)/LDLR(-)(/-) (n = 11) or apoE(-)(/-)/LDLR(-)(/-) (n = 14) marrow. Although there were no differences between the two groups in lipid levels at baseline or at 5 and 9 weeks after transplantation, apoE levels in the apoE(+)(/+)LDLR(-)(/-)-->apoE(-)(/-)/LDLR(-)(/-) mice increased to 4 times the apoE levels of normal mice. This resulted in a 60% decrease in aortic atherosclerosis in the apoE(+)(/+)/LDLR(-)(/-)-->apoE(-)(/-)/LDLR(-)(/-) compared with the apoE(-)(/-)/LDLR(-)(/-)-->apoE(-)(/-)/LDLR(-)(/-) controls, (15957 +/- 1907 vs. 40115 +/- 8302 micro m(2) +/- SEM, respectively). In a separate experiment, apoE(+)(/+)/LDLR(-)(/-) mice were transplanted with either apoE(+)(/+)/LDLR(-)(/-) or apoE(-)(/-)/LDLR(-)(/-) marrow and placed on a high-fat diet for 8 weeks. In the absence of macrophage apoE, lesion area was increased by 75% in the aortic sinus and by 56% in the distal aorta. These data show that physiologic levels of macrophage apoE in the vessel wall are anti-atherogenic in conditions of severe hyperlipidemia and can affect later stages of plaque development.     

Mycoplasma pneumoniae and/or Chlamydophila pneumoniae inoculation causing different aggravations in cholesterol-induced atherosclerosis in apoE KO male mice

Background  

Chamydophila pneumoniae (CP) and/or Mycoplasma pneumoniae (MP) are two bacteria detected in vulnerable atheromas. In this study we aimed to analyze whether CP and/or MP aggravates atherosclerosis induced by cholesterol-enriched diet in C57BL/6 apoE KO male mice. Thirty male apoE KO mice aged eight weeks fed by a diet containing 1% cholesterol until 32 weeks of age were divided into four groups: the first was inoculated with CP (n = 7), the second with MP (n = 12), the third with both CP + MP (n = 5), and the fourth with saline (sham n = 6). The animals were re-inoculated at 36 weeks of age, and sacrificed at 40 weeks of age. Two ascending aorta and one aortic arch segments were sampled. In the most severely obstructed segment, vessel diameter, plaque height, percentage of luminal obstruction and the degree of adventitial inflammation were analyzed. The plaque area/intimal surface ratio was obtained by measuring all three segments. The adventitial inflammation was semiquantified (0 absent, 1 mild, 2 moderate, and 3 diffuse).     

eNOS protects from atherosclerosis despite relevant superoxide production by the enzyme in apoE mice

Background

All three nitric oxide synthase (NOS) isoforms are expressed in atherosclerotic plaques. NOS enzymes in general catalyse NO production. However, under conditions of substrate and cofactor deficiency, the enzyme directly catalyse superoxide formation. Considering this alternative chemistry, the effects of NOS on key events in spontaneous hyperlipidemia driven atherosclerosis have not been investigated yet. Here, we evaluate how endothelial nitric oxide synthase (eNOS) modulates leukocyte/endothelial- (L/E) and platelet/endothelial- (P/E) interactions in atherosclerosis and the production of nitric oxide (NO) and superoxide by the enzyme.

Principal Findings

Intravital microscopy (IVM) of carotid arteries revealed significantly increased L/E-interactions in apolipoproteinE/eNOS double knockout mice (apoE^−/−/eNOS^−/−), while P/E-interactions did not differ, compared to apoE^−/−. eNOS deficiency increased macrophage infiltration in carotid arteries and vascular cell adhesion molecule-1 (VCAM-1) expression, both in endothelial and smooth muscle cells. Despite the expression of other NOS isoforms (inducible NOS, iNOS and neuronal NOS, nNOS) in plaques, Electron Spin Resonance (ESR) measurements of NO showed significant contribution of eNOS to total circulating and vascular wall NO production. Pharmacological inhibition and genetic deletion of eNOS reduced vascular superoxide production, indicating uncoupling of the enzyme in apoE^−/− vessels.

Conclusion

Overt plaque formation, increased vascular inflammation and L/E- interactions are associated with significant reduction of superoxide production in apoE^−/−/eNOS^−/− vessels. Therefore, lack of eNOS does not cause an automatic increase in oxidative stress. Uncoupling of eNOS occurs in apoE^−/− atherosclerosis but does not negate the enzyme''s strong protective effects.     

Role of apoE in conformation-prone diseases and atherosclerosis

Three isoforms of human plasma apolipoprotein E (apoE) are ligands to lipoprotein receptors and influence in different manner the synthesis and catabolism of pro-atherogenic triglyceride-rich lipoproteins. Among three isoforms, the apoE4 isoform is associated with increased frequency of atherosclerosis and Alzheimer’s disease (AD). The conformational transitions of β-amyloid (Aβ) influenced by apoE and serum amyloid P (SAP) component are key events in AD development, the accumulation of intermediate diffusible and soluble oligomers of Aβ being of particular significance. SAP and apoE, in a different manner for the three isoforms, serve as “pathological” chaperones during the aggregation of Aβ considered as a conformation-prone process. In turn, apoE consisting of two domains self-associates in solution and intermediate structures differently populated for the three isoforms exist. The different structures of the three isoforms determine their different distribution among various plasma lipoproteins. The structural and metabolic consideration of the common apoE pathway(s) in two pathologies assumes four molecular targets for AD correction: (i) inhibition of the accumulation of diffusible soluble Aβ oligomers; (ii) inhibition of apoE synthesis and secretion by astrocytes, in particular, under lipid-lowering therapy; (iii) inhibition of the binding of apoE and/or SAP to Aβ; (iv) stimulation of the expression of cholesterol transporter ABCA1. Published in Russian in Biokhimiya, 2006, Vol. 71, No. 7, pp. 876–881.     

姜黄素对9月龄APPswe／PSldE9双转基因小鼠行为学的影响

目的应用Morris水迷宫,测试AD模型APPswe／PSldE9双转基因小鼠定位航行及空间搜索等学习记忆和记忆保持能力,评价姜黄素对APPswe／PSldE9双转基因小鼠认知功能的影响。方法将3月龄的APPswe／PSldE9双转基因小鼠随机分为模型组、罗格列酮组（10ms／kg·d）、姜黄素高（400Ing／kg·d）、中（200ing／kg·d）、低剂量组（100mg,,kg·d）,每组6只;并以同月龄遗传背景相同的C57／BL6J小鼠作为对照组。每天灌胃给药1次,连续灌胃6个月。应用Morris水迷宫进行行为学检测。结果姜黄素对APPswe／PSldE9双转基因小鼠空间学习记忆能力障碍有改善作用,尤以姜黄素大剂量和中剂量组效果比较明显。结论姜黄素能改善APPswe／PSldE9双转基因小鼠的认知功能。     

Decreased content,rate of synthesis and export of cholesterol in the brain of apoE knockout mice

Apolipoprotein E knockout (apoE-KO) mice present synaptic loss, cognitive dysfunction, and high plasma lipid levels that may affect brain function simulating Alzheimer disease. Plasma and brain sterols were measured in apoE-KO and in wild type control mice on a cholesterol-free, phytosterol-containing diet by gas chromatography coupled to a mass spectrometer. Plasma cholesterol and phytosterols (campesterol and sitosterol) were higher in apoE-KO compared to control mice. Cholesterol precursors (desmosterol and lathosterol) were not detected in plasma of control mice but were present in apoE-KO mice. In the brain amounts of cholesterol, desmosterol, campesterol and 24-hydroxycholesterol were significantly lower in apoE-KO than in controls. There is a tendency in apoE-KO for lower values of 7α-hydroxycholesterol and 7β-hydroxycholesterol. Cholesterol content, synthesis rates (desmosterol) and export of 24-hydroxycholesterol are reduced in the brain of the severe hypercholesterolemic apoE-KO mice.     

Effects of coexpression of the LDL receptor and apoE on cholesterol metabolism and atherosclerosis in LDL receptor-deficient mice

The low density lipoprotein receptor (LDLR) plays a major role in regulation of plasma cholesterol levels as a ligand for apolipoprotein B-100 and apolipoprotein E (apoE). Consequently, LDLR-deficient mice fed a Western-type diet develop significant hypercholesterolemia and atherosclerosis. ApoE not only mediates uptake of atherogenic lipoproteins via the LDLR and other cell-surface receptors, but also directly inhibits atherosclerosis. In this study, we examined the hypothesis that coexpression of the LDLR and apoE would have greater effects than either one alone on plasma cholesterol levels and the development of atherosclerosis in LDLR-deficient mice. LDLR-deficient mice fed a Western-type diet for 10 weeks were injected with recombinant adenoviral vectors encoding the genes for human LDLR, human apoE3, both LDLR and apoE3, or lacZ (control). Plasma lipids were analyzed at several time points after vector injection. Six weeks after injection, mice were analyzed for extent of atherosclerosis by two independent methods. As expected, LDLR expression alone induced a significant reduction in plasma cholesterol due to reduced VLDL and LDL cholesterol levels, whereas overexpression of apoE alone did not reduce plasma cholesterol levels. When the LDLR and apoE were coexpressed in this model, the effects on plasma cholesterol levels were no greater than with expression of the LDLR alone. However, coexpression did result in a substantial increase in large apoE-rich HDL particles. In addition, although the combination of cholesterol reduction and apoE expression significantly reduced atherosclerosis, its effects were no greater than with expression of the LDLR or apoE alone. In summary, in this LDLR-deficient mouse model fed a Western-type diet, there was no evidence of an additive effect of expression of the LDLR and apoE on cholesterol reduction or atherosclerosis.