Aged ApoE Research Articles

Mid age APOE \u03b54 carriers show memory-related functional differences and disrupted structure-function relationships in\xa0hippocampal regions

Carriers of the APOE e4 allele are at higher risk of age-related cognitive decline and Alzheimer’s disease (AD). The underlying neural mechanisms are uncertain, but genotype differences in medial temporal lobe (MTL) functional activity and structure at mid-age might contribute. We tested 16 non-e4 and 16 e4 carriers (aged 45–55) on a subsequent memory task in conjunction with MRI to assess how hippocampal volume (from T1 structural) and microstructure (neurite orientation-dispersion, from NODDI) differs by genotype and in relation to memory encoding. No previous study has investigated APOE effects on hippocampal microstructure using NODDI. Recall performance did not differ by genotype. A genotype by condition interaction in left parahippocampus indicated that in e4 carriers activity did not differentiate subsequently remembered from forgotten words. Hippocampal volumes and microstructure also did not differ by genotype but hippocampal volumes correlated positively with recognition performance in non-e4 carriers only. Similarly, greater hippocampal neurite orientation-dispersion was linked to better recall but only in non-e4s. Thus, we suggest that mid-age e4 carriers show a breakdown of normal MTL activation and structure-performance relationships. This could reflect an inability to utilise compensatory mechanisms, and contribute to higher risk of cognitive decline and AD in later life.

Diversification and CXCR4-Dependent Establishment of the Bone Marrow B-1a Cell Pool Governs Atheroprotective IgM Production Linked to Human Coronary Atherosclerosis.

B-1 cell-derived natural IgM antibodies against oxidation-specific epitopes on low-density lipoprotein are anti-inflammatory and atheroprotective. Bone marrow (BM) B-1a cells contribute abundantly to IgM production, yet the unique repertoire of IgM antibodies generated by BM B-1a and the factors maintaining the BM B-1a population remain unexplored. CXCR4 (C-X-C motif chemokine receptor 4) has been implicated in human cardiovascular disease and B-cell homeostasis, yet the role of B-1 cell CXCR4 in regulating atheroprotective IgM levels and human cardiovascular disease is unknown. To characterize the BM B-1a IgM repertoire and to determine whether CXCR4 regulates B-1 production of atheroprotective IgM in mice and humans. Single-cell sequencing demonstrated that BM B-1a cells from aged ApoE-/- mice with established atherosclerosis express a unique repertoire of IgM antibodies containing increased nontemplate-encoded nucleotide additions and a greater frequency of unique heavy chain complementarity determining region 3 sequences compared with peritoneal cavity B-1a cells. Some complementarity determining region 3 sequences were common to both compartments suggesting B-1a migration between compartments. Indeed, mature peritoneal cavity B-1a cells migrated to BM in a CXCR4-dependent manner. Furthermore, BM IgM production and plasma IgM levels were reduced in ApoE-/- mice with B-cell-specific knockout of CXCR4, and overexpression of CXCR4 on B-1a cells increased BM localization and plasma IgM against oxidation specific epitopes, including IgM specific for malondialdehyde-modified LDL (low-density lipoprotein). Finally, in a 50-subject human cohort, we find that CXCR4 expression on circulating human B-1 cells positively associates with plasma levels of IgM antibodies specific for malondialdehyde-modified LDL and inversely associates with human coronary artery plaque burden and necrosis. These data provide the first report of a unique BM B-1a cell IgM repertoire and identifies CXCR4 expression as a critical factor selectively governing BM B-1a localization and production of IgM against oxidation specific epitopes. That CXCR4 expression on human B-1 cells was greater in humans with low coronary artery plaque burden suggests a potential targeted approach for immune modulation to limit atherosclerosis.

Association Between ApoE Polymorphism in Obesity Markers in Healthy Adults Who Follow the Greek Orthodox Fasting Rules

Aim: To examine the association between ApoE genetic polymorphisms and BMI.Methods: This case control study of randomly selected, free living individuals from North Greece investigated whether traditional Greek Orthodox dietary practices could affect obesity markers independent of genetic influences, by examining the Waist circumference (WC), waist hip ratio (WHR) and % fat mass (% FM), were measured in healthy adults who follow the rules of Greek Orthodox fasting compared to those who did not. 382 subjects (246 women and 136 men) were included in the analysis, 161 fasters and 220 non-fasters as a control group. Results: Age affected obesity markers in all participants with more obesity in the older subjects. ApoE alleles did not differ between fasting and controls. When fasters where classified as obese and non-obese, there was no association with age (p>0,077). In the control group, BMI and WC were associated with age and gender and WHR with apoE alleles (p<0.001). In the fasting group these correlations are not observed (p=0.545 and p=0.365 respectively). Interactions between independent variables (sex, age apoE alleles and fasting status) and their influence on BMI, %BF and WHR. ApoE alleles and age significantly influence WHR (p=0.014). Conclusions: In the present study we found that the effect of ApoE alleles on adiposity was associated with age. In conclusion, even if genetic risks factor influence the susceptibility to obesity and cardiometabolic disorders, lifestyle changes may ameliorate these effects.

Aldehyde dehydrogenase 2 deficiency promotes atherosclerotic plaque instability through accelerating mitochondrial ROS-mediated vascular smooth muscle cell senescence

Previous evidence has indicated a beneficial role for aldehyde dehydrogenase 2 (ALDH2) in suppressing atherosclerotic plaque progression and instability. However, the underlying mechanism remains somewhat elusive. This study was designed to examine the effect of ALDH2 deficiency on high-cholesterol diet-induced atherosclerotic plaque progression and plaque vulnerability in atherosclerosis-prone ApoE knockout (ApoE−/−) mice with a focus on foam cell formation in macrophages and senescence of vascular smooth muscle cells (VSMCs). Serum lipid profile, plaque progression, and plaque vulnerability were examined in ApoE−/− and ALDH2/ApoE double knockout (ALDH2−/−ApoE−/−) mice after high-cholesterol diet intake for 8 weeks. ALDH2 deficiency increased the serum levels of triglycerides while it decreased levels of total cholesterol and high-density lipoprotein cholesterol. Unexpectedly, ALDH2 deficiency reduced the plaque area by 58.9% and 37.5% in aorta and aortic sinus, respectively. Plaque instability was aggravated by ALDH2 deficiency along with the increased necrotic core size, decreased collagen content, thinner fibrous cap area, decreased VSMC content, and increased macrophage content. In atherosclerotic lesions, ALDH2 protein was located in both macrophages and VSMCs. Further results revealed downregulated ALDH2 expression in aorta of aged ApoE−/− mice compared with young mice. However, in vitro study suggested that ALDH2 expression was upregulated in bone marrow-derived macrophages (BMDMs) with an opposite effect in VSMCs following 80 μg/ml oxidized low-density lipoprotein (oxLDL) treatment. Interestingly, ALDH2 deficiency displayed little effect in oxLDL-induced foam cell formation from BMDMs, while ALDH2 knockdown by siRNA and ALDH2 overexpression by lentivirus infection promoted and retarded oxLDL-induced VSMC senescence, respectively. Mechanistically, ALDH2 mitigated oxLDL-induced overproduction of mitochondrial reactive oxygen species (mROS) and activation of downstream p53/p21/p16 pathway. Clearance of mROS by mitoTEMPO significantly reversed the promotive effect of ALDH2 knockdown on VSMC senescence. Taken together, our data revealed that ALDH2 deficiency suppressed atherosclerotic plaque area while facilitating plaque instability possibly through accelerating mROS-mediated VSMC senescence.This article is part of a Special Issue entitled: Genetic and epigenetic regulation of aging and longevity edited by Jun Ren & Megan Yingmei Zhang.

The Effects of Endurance Exercise and Diet on Atherosclerosis in Young and Aged ApoE–/– and Wild-Type Mice

Background: Atherosclerosis is the leading cause of death worldwide. The disease development is by and large driven by old age and lifestyle factors, such as diet, physical activity, and smoking. In the present study, we have investigated the effect of exercise and diet on the development of atherosclerosis in young and aged mice. Objective: This study aimed at comparing multiple age-dependent factors that may influence atherosclerosis in a transgenic mouse model. Methods: Young (14 weeks) and aged (49–52 weeks) C57BL/6 wild-type (WT) and atherosclerosis-prone ApoE^–/– mice were subjected to physical endurance exercise on a treadmill, with or without a high-fat diet. Five weeks later, the frequencies of regulatory T cells (T_REGs) in lymph nodes were assessed by flow cytometry, plasmatic cytokines (interleukin [IL]-1β, IL-6, IL-10, IL-17, interferon-γ, tumor necrosis factor-α, and transforming growth factor [TGF]-β₁) levels were determined by Luminex assay. Lipids (cholesterol and triglycerides) and anti-heat shock protein 60 (HSP60) autoantibodies were measured by ELISA. Aortic lesion sizes were assessed by en face imaging. Microarray analysis and qPCR of skeletal muscle gene expression were also performed. Results: Exercise leads to a reduction of aortic lesions in young ApoE^–/– and aged WT mice independent of diet. In most groups, this reduction was followed by an increased proportion of T_REGs and TGF-β₁ levels. Moreover, gene expression analysis showed that exercise seems to affect the AMPK signaling pathway. In particular, PGC-1α₁ mRNA was induced in aged WT mice, whereas it was reduced in young ApoE^–/– mice. In addition, GSEA analysis showed a marked reduction in the insulin signaling pathway in aged ApoE^–/– mice. Conclusion: Practicing endurance exercise seems to be enough for reducing early aortic lesion formation, independent of diet. However, this was only true in mice with smaller aortic lesions, since mice with large, advanced, complicated atherosclerotic plaques did not show any reduction in lesion size with exercise training.

Neutrophils recruited by leukotriene B4 induce features of plaque destabilization during endotoxaemia.

Both leukotrienes and neutrophils have been linked to plaque destabilization. Despite being evoked, the role of leukotriene B4 (LTB4) in neutrophil recruitment to plaques and the concomitant effects of these two actors on plaque stability remain to be proven. Since both actors are elicited during endotoxaemia, a condition associated with the risk of cardiovascular events, we investigated whether endotoxaemia promotes LTB4-mediated neutrophil infiltration in plaques and explored the roles of LTB4 and neutrophils in plaque destabilization. Endotoxaemia induced by repeated peritoneal endotoxin injections at a non-lethal dose (1.5 mg/kg, 5 days) in chow-fed aged Apoe-/- mice (over 45 weeks old) resulted in neutrophil infiltration and activation in plaques. Subsequently to neutrophil invasion, plaques exhibited increased features of vulnerability: reduced collagen content, expanded necrotic cores, and thinned fibrous caps. These plaque features were reproduced by direct deposition of isolated neutrophils onto murine atheromatous carotid arteries in an in vivo assay. In endotoxemic mice, plaques produced increased amounts of LTB4. Genomic or pharmacological impairments of this production reduced neutrophil infiltration, collagenolysis, and apoptosis of smooth muscle cells in plaques of endotoxemic mice. Furthermore, conditioned media of human culprit plaques (CPs) contained more LTB4 than non-CPs and levels of LTB4 correlated to both neutrophil activation markers and endotoxin releases in CPs. These results show that the increased neutrophil recruitment elicited by LTB4 contributes to increase features of plaque destabilization in endotoxemic contexts and point out LTB4 as a potential therapeutic target in atherosclerosis.

Fibronectin Containing Extra Domain A Induces Plaque Destabilization in the Innominate Artery of Aged Apolipoprotein E-Deficient Mice.

Fibronectin containing extra domain A (Fn-EDA) is an endogenous ligand of TLR4 (toll-like receptor 4) and is abundant in the extracellular matrix of advanced atherosclerotic lesions in human and mice. Irrespective of sex, deletion of Fn-EDA reduces early atherosclerosis in apolipoprotein E-deficient (Apoe-/-) mice. However, the contribution of Fn-EDA in advanced atherosclerosis remains poorly characterized. We determined the contribution of Fn-EDA in advanced atherosclerotic lesions of aged (1-year-old) Apoe-/- mice. Plaque composition was determined in the innominate artery, a plaque instability site that is known to mimic several histological features of vulnerable human plaques. Female Apoe-/-, Fn-EDA-/-Apoe-/-, TLR4-/-Apoe-/-, and Fn-EDA-/-TLR4-/-Apoe-/- mice were fed a high-fat Western diet for 44 weeks. Fn-EDA-/-Apoe-/- mice exhibited reduced plaque size characterized by smaller necrotic cores, thick fibrous caps containing abundant vascular smooth muscle cells and collagen, reduced CD68/MMP9 (matrix metalloproteinase 9)-positive content, less accumulation of MMP-cleaved extracellular matrix aggrecan, and decreased vascular smooth muscle cell and macrophage apoptosis (P<0.05 versus Apoe-/- mice). Together these findings suggest that Fn-EDA induces plaque destabilization. Deletion of TLR4 reduced histological features of plaque instability in Apoe-/- mice but did not further reduce features of plaque destabilization in Fn-EDA-/-Apoe-/- mice, suggesting that TLR4 may contribute to Fn-EDA-induced plaque destabilization. Fn-EDA potentiated TLR4-dependent MMP9 expression in bone marrow-derived macrophages, suggesting that macrophage TLR4 may contribute to Fn-EDA-mediated plaque instability. Fn-EDA induces histological features of plaque instability in established lesions of aged Apoe-/- mice. The abundance of Fn-EDA in advanced atherosclerotic lesions may increase the risk of plaque destabilization.

Comparison of atherosclerosis between ApoE and LDL-R knockout mice in different diet by vivo ultrasound biomicroscopy

Objective To evaluate the different change in atherosclerosis between apolipoprotein E knockout (ApoE-/-) mice and low density lipoprotein receptor knockout (LDL-R-/-) mice in different diet by vivo ultrasound biomicroscopy(UBM). Methods Thirty-two 8 weeks age ApoE-/- mice and twenty-eight 20 weeks age LDL-R-/- mice were selected, and each mouse model were divided into four groups randomly according to weight. Two groups of each model were fed with normal diet for 8 weeks and 16 weeks respectively as general groups, and two other groups were fed with west diet as high-fat groups. Intima-media thickness(IMT) in the aortic root of all groups were assessed by Vevo 770 UBM, and all measurements of UBM were compared with histopathology and blood-fat. Results ①Thicken wall or plaque in aortic root showed by UBM and histopathology could be found in ApoE-/- mice in all diet conditions, but the changes in LDL-R-/- mice only could be found in high-fat diet conditions; ②IMT of ApoE-/- mice measured in histopathology were significantly higher than LDL-R-/- mice in all diet condition (P<0.05), but in UBM, the IMT of ApoE-/- mice showed significantly higher than that of LDL-R-/- mice only in general diet groups and 8 weeks high-fat diet group (P<0.05); ③In blood-fat, the total cholesterol (TC) in ApoE-/- mice were significantly higher than that of LDL-R-/- mice in all diet conditions (P<0.05). But triglyceride (TG) was higher only in general diet when it was compared between ApoE-/- mice and LDL-R-/- mice. Conclusions It is recommend to select ApoE-/- mice as animal model in atherosclerosis study rather than LDL-R-/- mice, because the higher serum TC and higher susceptible of atherosclerosis in ApoE-/- mice. The west diet is necessary if LDL-R-/- mice was used to atherosclerosis study. Key words: Ultrasonography; Ultrasound biomicroscopy; Mice, knock out; Apolipoproteins E; Low density lipoprotein receptor; Atherosclerosis

Pioglitazone attenuates aging-related disorders in aged apolipoprotein E deficient mice

Pioglitazone (Piog) activates peroxisome proliferator activated receptor-γ (PPARγ) and is widely used in clinic for the treatment of diabetes mellitus. PPARγ in various tissues has the essential regulatory role of multiple metabolic function, suggest that PPARγ signaling may contribute to aging processes. However, little is known about the consequences of Piog on aging in aged animal models. We used apolipoprotein E deficient (apoE−/−) mice model to evaluate the effects of Piog on aging-related disorders. Our results showed that long-term and low-dose Piog treatment significantly reduced aortic atherosclerosis, aging-related renal glomerulosclerosis and interstitial fibrosis, and hepatic steatosis, while improved the dermis in skin atrophy, compared to the control group. These morphological alterations were linked to the role of Piog, including regulation of plasma cholesterol and triglycerides (TG) levels, increased antioxidant superoxide dismutase (SOD) activity and decreased myeloperoxidase (MPO) activity. Moreover, accompanied with up-regulation of PPARγ expression, Piog had obviously increased the mRNA levels of anti-aging genes Sirtuin1 and Klotho, decreased the p53 protein level, and altered the expression of several genes involving cholesterol excretion, TG biosynthesis and inflammation in the liver. In conclusion, Piog treatment is effective to modulate the oxidative and inflammatory status, cell senescence, and lipid metabolism, contributing to attenuate several aging-related disorders in the aged apoE−/− mice, thereby maybe a promising protective therapy of aging and age-related diseases.

Oral Tolerization with Mycobacterial Heat Shock Protein 65 Reduces Chronic Experimental Atherosclerosis in Aged Mice

Background: Atherosclerosis is a chronic inflammatory disease of the artery wall where both innate and adaptive immunity play important roles. Modulation of the immune response against the stress protein antigen, heat shock protein (HSP) 60, by administration of mycobacterial HSP65 (mbHSP65) orally and/or nasally shows promising therapeutic results in young animals in the sense of less severe experimental atherosclerosis; however, the case of aged animals with already established atherosclerosis has so far never been investigated. Objective: To investigate if mbHSP65 immunization would further accelerate atherosclerotic progression in aged ApoE^-/- mice (18 months old) with already long-established atherosclerosis and if these mice could be orally tolerized against mbHSP65. Methods: Aged wild-type (WT) and ApoE^-/- mice (65 weeks) were immunized and/or orally treated with mbHSP65 and then either kept on normal chow or changed to high-cholesterol diet (HCD). Atherosclerosis was assessed by en face analysis and the number of CD4⁺CD25⁺FoxP3⁺ T regulatory cells (Tregs) was assessed by flow cytometry in lymph node and spleen cells. Total cholesterol and triglyceride levels were determined. Soluble mammalian HSP60 and anti-mouse HSP60 (mHSP60) and anti-mbHSP65 antibodies were detected by enzyme-linked immunosorbent assay. Results: As expected, aged WT mice had only minor lesions in the aorta, which did not change under HCD for 14 weeks. Aged ApoE^-/- mice already had large complicated plaques, which increased in size under HCD. mbHSP65 immunization led to a significant aggravation of atherosclerosis in both WT and ApoE^-/- mice irrespective of the nature of their diet. This increase was accompanied by increased titers of both anti-mHSP60 and anti-mbHSP65 antibodies in the circulation. The increased plaque formation could be significantly diminished with oral mbHSP65 tolerization. An increased number of Tregs and lower or unchanged levels of cholesterol and triglycerides were associated with the reduced size of aortal lesions. Conclusion: Oral tolerization against mbHSP65 could be used both to prevent and to treat chronic atherosclerosis in aged individuals.

Advanced atherosclerosis is associated with inflammation, vascular dysfunction and oxidative stress, but not hypertension

Although hypertension may involve underlying inflammation, it is unknown whether advanced atherosclerosis − a chronic inflammatory condition − can by itself promote hypertension. We thus tested if advanced atherosclerosis in chronically hypercholesterolemic mice is associated with systemic and end-organ inflammation, vascular dysfunction and oxidative stress, and whether blood pressure is higher than in control mice. Male ApoE−/− and wild-type (C57Bl6J) mice were placed on a high fat or chow diet, respectively, from 5 to 61 weeks of age. Expression of several cytokines (including IL-6, TNF-α, IFN-γ and/or IL-1β) was elevated in plasma, brain, and aorta of ApoE−/− mice. Aortic superoxide production was ∼3.5-fold greater, and endothelium-dependent relaxation was markedly reduced in aorta and mesenteric artery of ApoE−/− versus wild-type mice. There was no difference in blood pressure of aged ApoE−/− (104±3mmHg, n=13) and wild-type mice (113±1mmHg, n=18). To clarify any effects of aging alone, findings from 61 week-old wild-type mice were compared with those from young (8–12 weeks old) chow-fed wild-type mice. The data indicate that aging alone increased renal and aortic expression of numerous cytokines (including CCL2, CCL7 and IL-1β). Aging had no effect on blood pressure, systemic inflammation, oxidative stress or endothelial function. Despite systemic and end-organ inflammation, oxidative stress and endothelial dysfunction, advanced atherosclerosis does not necessarily result in elevated blood pressure.

MicroRNA-146a Induces Lineage-Negative Bone Marrow Cell Apoptosis and Senescence by Targeting Polo-Like Kinase 2 Expression.

Lineage-negative bone marrow cells (lin- BMCs) are enriched in endothelial progenitor cells and mediate vascular repair. Aging-associated senescence and apoptosis result in reduced number and functionality of lin- BMCs, impairing their prorepair capacity. The molecular mechanisms underlying lin- BMC senescence and apoptosis are poorly understood. MicroRNAs (miRNAs) regulate many important biological processes. The identification of miRNA-mRNA networks that modulate the health and functionality of lin- BMCs is a critical step in understanding the process of vascular repair. The aim of this study was to characterize the role of the miR-146a-Polo-like kinase 2 (Plk2) network in regulating lin- BMC senescence, apoptosis, and their angiogenic capability. Transcriptome analysis in lin- BMCs isolated from young and aged wild-type and ApoE-/- (apolipoprotein E) mice showed a significant age-associated increase in miR-146a expression. In silico analysis, expression study and Luciferase reporter assay established Plk2 as a direct target of miR-146a. miR-146a overexpression in young lin- BMCs inhibited Plk2 expression, resulting in increased senescence and apoptosis, via p16Ink4a/p19Arf and p53, respectively, as well as impaired angiogenic capacity in vitro and in vivo. Conversely, suppression of miR-146a in aged lin- BMCs increased Plk2 expression and rejuvenated lin- BMCs, resulting in decreased senescence and apoptosis, leading to improved angiogenesis. (1) miR-146a regulates lin- BMC senescence and apoptosis by suppressing Plk2 expression that, in turn, activates p16Ink4a/p19Arf and p53 and (2) modulation of miR-146a or its target Plk2 may represent a potential therapeutic intervention to improve lin- BMC-mediated angiogenesis and vascular repair.

421 - Changes in Ceramide Levels in Various Diseases Are Associated with Oxidative Stress

Ceramide is a bioactive lipid that induces cellular apoptosis, proliferation, and differentiation. Deficiency of acid sphingomyelinase, which synthesizes ceramide, has been reported to result in smaller aortic root lesions in Western diet-fed Ldl -/- mice. Thus, ceramide is predicted to play a role in atherosclerosis pathogenesis. Therefore, using animal models, we investigated whether ceramide levels were affected by oxidative stress in diseases such as atherosclerosis, diabetes, and fulminant hepatitis. The experiments were performed under acute oxidative stress caused by carbon tetrachloride (CCl 4 ) intoxication and chronic oxidative stress in diabetic rats and in aged apolipoprotein E knock out (apoE -/- ) mice. Total ceramide concentrations significantly increased in the liver, brain, kidney, and plasma of CCl 4 -intoxicated rats. This increase was primarily derived from an increase in neutral sphingomyelinase activity in the liver 2 hours after intoxication with CCl 4 and was consistent with the decrease in the GSH/GSSG ratio in the liver. In contrast, secretory sphingomyelinase was stimulated during prolonged oxidative stress associated with diabetes and atherosclerosis. After 2 weeks of streptozotocin administration, plasma secretory sphingomyelinase activity was significantly increased, resulting in elevated ceramide concentrations, whereas neutral sphingomyelinase activity was unchanged in the kidney and liver. Plasma ceramide concentrations and secretory sphingomyelinase activity also increased in aged apoE -/- mice. In conclusion, ceramide levels increased in both acute and chronic oxidative stress-related diseases; however, the enzymes responsible for these changes differed. Based on these results, we propose that antioxidants can prevent ceramide production and ameliorate the exacerbation of oxidative stress-related diseases.

Aldehyde dehydrogenase 2 inhibits inflammatory response and regulates atherosclerotic plaque.

Previous studies demonstrated that aldehyde dehydrogenase 2 (ALDH2) rs671 polymorphism, which eliminates ALDH2 activity down to 1%-6%, is a susceptibility gene for coronary disease. Here we investigated the underlying mechanisms based on our prior clinical and experimental studies. Male apoE−/− mice were transfected with GFP, ALDH2-overexpression and ALDH2-RNAi lentivirus respectively (n=20 each) after constrictive collars were placed around the right common carotid arteries. Consequently, ALDH2 gene silencing led to an increased en face plaque area, more unstable plaque with heavier accumulation of lipids, more macrophages, less smooth muscle cells and collagen, which were associated with aggravated inflammation. However, ALDH2 overexpression displayed opposing effects. We also found that ALDH2 activity decreased in atherosclerotic plaques of human and aged apoE−/− mice. Moreover, in vitro experiments with human umbilical vein endothelial cells further illustrated that, inhibition of ALDH2 activity resulted in elevating inflammatory molecules, an increase of nuclear translocation of NF-κB, and enhanced phosphorylation of NF-κB p65, AP-1 c-Jun, Jun-N terminal kinase and p38 MAPK, while ALDH2 activation could trigger contrary effects. These findings suggested that ALDH2 can influence plaque development and vulnerability, and inflammation via MAPK, NF-κB and AP-1 signaling pathways.

The Effect of a High-Fat Diet on Brain Plasticity, Inflammation and Cognition in Female ApoE4-Knockin and ApoE-Knockout Mice.

Apolipoprotein E4 (ApoE4), one of three common isoforms of ApoE, is a major risk factor for late-onset Alzheimer disease (AD). ApoE-deficient mice, as well as mice expressing human ApoE4, display impaired learning and memory functions and signs of neurodegeneration. Moreover, ApoE protects against high-fat (HF) diet induced neurodegeneration by its role in the maintenance of the integrity of the blood-brain barrier. The influence of a HF diet on the progression of AD-like cognitive and neuropathological changes was assessed in wild-type (WT), human ApoE4 and ApoE-knockout (ApoE-/-) mice to evaluate the modulatory role of ApoE in this process. From 12 months of age, female WT, ApoE4, and ApoE-/- mice were fed either a standard or a HF diet (19% butter, 0.5% cholate, 1.25% cholesterol) throughout life. At 15 months of age mice performed the Morris water maze, evaluating spatial learning and memory. ApoE-/- showed increased spatial learning compared to WT mice (p = 0.009). HF diet improved spatial learning in WT mice (p = 0.045), but did not affect ApoE4 and ApoE-/- mice. Immunohistochemical analyses of the hippocampus demonstrated increased neuroinflammation (CD68) in the cornu ammonis 1 (CA1) region in ApoE4 (p = 0.001) and in ApoE-/- (p = 0.032) mice on standard diet. HF diet tended to increase CD68 in the CA1 in WT mice (p = 0.052), while it decreased in ApoE4 (p = 0.009), but ApoE-/- remained unaffected. A trend towards increased neurogenesis (DCX) was found in both ApoE4 (p = 0.052) and ApoE-/- mice (p = 0.068). In conclusion, these data suggest that HF intake induces different effects in WT mice compared to ApoE4 and ApoE-/- with respect to markers for cognition and neurodegeneration. We propose that HF intake inhibits the compensatory mechanisms of neuroinflammation and neurogenesis in aged female ApoE4 and ApoE-/- mice.

Maternal high-fat feeding in pregnancy programs atherosclerotic lesion size in the ApoE*3 Leiden mouse.

Periods of rapid growth seen during the early stages of fetal development, including cell proliferation and differentiation, are greatly influenced by the maternal environment. We demonstrate here that over-nutrition, specifically exposure to a high-fat diet in utero, programed the extent of atherosclerosis in the offspring of ApoE*3 Leiden transgenic mice. Pregnant ApoE*3 Leiden mice were fed either a control chow diet (2.8% fat, n=12) or a high-fat, moderate-cholesterol diet (MHF, 19.4% fat, n=12). Dams were fed the chow diet during the suckling period. At 28 days postnatal age wild type and ApoE*3 Leiden offspring from chow or MHF-fed mothers were fed either a control chow diet (n=37) or a diet rich in cocoa butter (15%) and cholesterol (0.25%), for 14 weeks to induce atherosclerosis (n=36). Offspring from MHF-fed mothers had 1.9-fold larger atherosclerotic lesions (P&lt;0.001). There was no direct effect of prenatal diet on plasma triglycerides or cholesterol; however, transgenic ApoE*3 Leiden offspring displayed raised cholesterol when on an atherogenic diet compared with wild-type controls (P=0.031). Lesion size was correlated with plasma lipid parameters after adjustment for genotype, maternal diet and postnatal diet (R 2=0.563, P&lt;0.001). ApoE*3 Leiden mothers fed a MHF diet developed hypercholesterolemia (plasma cholesterol two-fold higher than in chow-fed mothers, P=0.011). The data strongly suggest that maternal hypercholesterolemia programs later susceptibility to atherosclerosis. This is consistent with previous observations in humans and animal models.

Sirt1 is involved in decreased bone formation in aged apolipoprotein E-deficient mice.

Apolipoprotein E (ApoE) plays an important role in the transport and metabolism of lipids. Recent studies show that bone mass is increased in young apoE(-/-) mice. In this study we investigated the bone phenotype and metabolism in aged apoE(-/-) mice. Femurs and tibias were collected from 18- and 72-week-old apoE(-/-) mice and their age-matched wild-type (WT) littermates, and examined using micro-CT and histological analysis. Serum levels of total cholesterol, oxidized low-density lipoprotein (ox-LDL) and bone turnover markers were measured. Cultured bone mesenchymal stem cells (BMSCs) from tibias and femurs of 18-week-old apoE(-/-) mice were used in experiments in vitro. The expression levels of Sirt1 and Runx2 in bone tissue and BMSCs were measured using RT-PCR and Western blot analysis. Compared with age-matched WT littermates, young apoE(-/-) mice exhibited high bone mass with increased bone formation, accompanied by higher serum levels of bone turnover markers OCN and TRAP5b, and higher expression levels of Sirt1, Runx2, ALP and OCN in bone tissue. In contrast, aged apoE(-/-) mice showed reduced bone formation and lower bone mass relative to age-matched WT mice, accompanied by lower serum OCN levels, and markedly reduced expression levels of Sirt1, Runx2, ALP and OCN in bone tissue. After BMSCs were exposed to ox-LDL (20 μg/mL), the expression of Sirt1 and Runx2 proteins was significantly increased at 12 h, and then decreased at 72 h. Treatment with the Sirt1 inhibitor EX527 (10 μmol/L) suppressed the expression of Runx2, ALP and OCN in BMSCs. In contrast to young apoE(-/-) mice, aged apoE(-/-) mice showe lower bone mass than age-matched WT mice. Long-lasting exposure to ox-LDL decreases the expression of Sirt1 and Runx2 in BMSCs, which may explain the decreased bone formation in aged apoE(-/-) mice.

Abstract P182: Advanced Atherosclerosis is Associated with Systemic and End-organ Inflammation, Vascular Oxidative Stress and Endothelial Dysfunction but not Hypertension in Mice

Introduction: Evidence suggests that hypertension involves underlying inflammation, however whether atherosclerosis - a chronic inflammatory condition - can cause hypertension is unknown. We tested whether blood pressure (BP) is higher in high-fat fed ApoE-/- vs chow-fed wild-type (WT) mice, and whether advanced atherosclerosis is associated with systemic and end-organ inflammation, oxidative stress and endothelial dysfunction. Methods: Male ApoE-/- and WT mice were placed on high fat and chow diets, respectively, from 5-56 weeks. To clarify the effects of ageing alone, aged WT mice were compared to young chow-fed WT mice (8-12 week old). We measured systolic BP, plasma cytokine levels, mRNA expression of inflammatory markers, vascular superoxide and endothelial function. Results: There was no difference in BP of aged ApoE-/- (104.2 ± 2.9 mmHg) and age-matched WT mice (113.2 ± 1.3 mmHg) (n=13-18, P&gt;0.05). However, plasma IL-6, TNF-α and IFN-γ were elevated in ApoE-/- by more than 2-fold vs age-matched WT (n=9-10, all P&lt;0.05), as was brain expression of IL-1β, IL-6, TNF-α, IFN-γ, TGFβ1, CCR2, CCL2, CCL7, CCL8, CCL12 and IL-10 (n=9-10, all P&lt;0.05), and aortic expression of IL-6, CCR2, CCL8 and CCL12 (n=6-8, all P&lt;0.05). Ageing, but not atherosclerosis, increased renal expression of IL-1β, IL-6, TNF-α, CCR2, CCL2, CCL7, CCL8, CCL12 and Foxp3, and aortic expression of CCL2, IL-10 and Foxp3 by at least 2-fold (n=6-10, all P&lt;0.05). In ApoE-/- aorta, Nox2-dependent superoxide production was 4-fold greater than in WT (n=5-6, P&lt;0.05), and endothelium-dependent vasorelaxation to carbachol was markedly reduced by more than half (n=5-7, P&lt;0.05). Ageing alone had no effect on BP, systemic inflammation or endothelial function. Conclusions: Despite the systemic and end-organ inflammation, oxidative stress and endothelial dysfunction, advanced atherosclerosis does not result in elevated BP.

NOX4 NADPH Oxidase-Dependent Mitochondrial Oxidative Stress in Aging-Associated Cardiovascular Disease.

Increased oxidative stress and vascular inflammation are implicated in increased cardiovascular disease (CVD) incidence with age. We and others demonstrated that NOX1/2 NADPH oxidase inhibition, by genetic deletion of p47phox, in Apoe(-/-) mice decreases vascular reactive oxygen species (ROS) generation and atherosclerosis in young age. The present study examined whether NOX1/2 NADPH oxidases are also pivotal to aging-associated CVD. Both aged (16 months) Apoe(-/-) and Apoe(-/-)/p47phox(-/-) mice had increased atherosclerotic lesion area, aortic stiffness, and systolic dysfunction compared with young (4 months) cohorts. Cellular and mitochondrial ROS (mtROS) levels were significantly higher in aortic wall and vascular smooth muscle cells (VSMCs) from aged wild-type and p47phox(-/-) mice. VSMCs from aged mice had increased mitochondrial protein oxidation and dysfunction and increased vascular cell adhesion molecule 1 expression, which was abrogated with (2-(2,2,6,6-Tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl)triphenylphosphonium chloride (MitoTEMPO) treatment. NOX4 expression was increased in the vasculature and mitochondria of aged mice and its suppression with shRNA in VSMCs from aged mice decreased mtROS levels and improved function. Increased mtROS levels were associated with enhanced mitochondrial NOX4 expression in aortic VSMCs from aged subjects, and NOX4 expression levels in arterial wall correlated with age and atherosclerotic severity. Aged Apoe(-/-) mice treated with MitoTEMPO and 2-(2-chlorophenyl)-4-methyl-5-(pyridin-2-ylmethyl)-1H-pyrazolo[4,3-c]pyridine-3,6(2H,5H)-dione had decreased vascular ROS levels and atherosclerosis and preserved vascular and cardiac function. These data suggest that NOX4, but not NOX1/2, and mitochondrial oxidative stress are mediators of CVD in aging under hyperlipidemic conditions. Regulating NOX4 activity/expression and using mitochondrial antioxidants are potential approaches to reducing aging-associated CVD.

Effects of β3-adrenoceptor activation on expression of pancreatic adrenoceptors and angiotensin II receptors in ApoE−/− mice

Hyperlipidemia can be harmful to the pancreas and β3-adrenoceptor agonist can improve lipid metabolism disorder. We aimed to study the effects of β3-adrenoceptor activation on glucose, insulin and the expression of pancreatic adrenoceptors and angiotensin II receptors. Ten C57BL/6J mice at the age of 10 weeks served as normal control, and forty age-matched apolipoprotein E knockout (ApoE−/−) mice were randomly divided into hyperlipidaemia model group, low-dose and high-dose β3-adrenoceptor agonist group and β3-adrenoceptor antagonist group. After 26 weeks of high-fat diet, treatments were given for 12 weeks. Serum glucose and insulin levels in 48 weeks old mice were measured using an automatic biochemical detector. Quantitative rt-PCR and Western blot were used to analyze the mRNA and protein expression of α1A-, α2A-, β2-, β3-adrenoceptors and angiotensin II type 1 and type 2 receptors in pancreas. We found that β3-adrenoceptor agonist could decrease serum glucose and insulin levels in aged ApoE−/− mice (P<0.01) and down-regulate the expression of α1A-adrenoceptor and angiotensin II type 1 receptor which were significantly increased in model mice (P<0.05, P<0.01). Compared with the model mice, α2A-, β2-, β3-adrenoceptor and angiotensin II type 2 receptor expression were up-regulated in β3-adrenoceptor agonist treat mice (P<0.05, P<0.01). These results suggest that chronic β3-adrenoceptor activation regulated the expression of adrenoceptors and angiontensin II receptors towards contrary direction, which indicates that there are interactions between β3-adrenoceptor and subtypes of adrenoceptor and angiotensin II receptor, and these interactions may play a protective role in pancreas and improve glucose metabolism disorders.