Food with calorie restriction reduces the development of atherosclerosis in apoE-deficient mice.

Calorie restriction (CR) ameliorates various diseases including cardiovascular disease. However, its protection and underlying mechanisms against atherosclerosis remain un-fully elucidated. In this study, we fed apoE deficient (apoE-/-) mice in Control group a high-fat diet (HFD, 21% fat plus 0.5% cholesterol) or in CR group a CR diet (CRD, 2% fat plus 0.5% cholesterol, ∼40% calorie restriction and same levels of cholesterol, vitamins, minerals and amino acids as in HFD). After 16 weeks feeding, compared with HFD, CRD substantially reduced atherosclerosis in mice. CRD increased SMC and collagen content but reduced macrophage content, necrotic core and vascular calcification in lesion areas. Mechanistically, CRD attenuated bodyweight gain, improved lipid profiles but had little effect on macrophage lipid metabolism. CRD also inhibited expression of inflammatory molecules in lesions. Taken together, our study demonstrates CRD effectively reduces atherosclerosis in apoE-/- mice, suggesting it as a potent and reproducible therapy for atherosclerosis management.

Would acetazolamide inhibit progression of atheromatous vascular calcification?

Vascular calcification is a recognised source of morbidity among mid-age and elderly subjects. Its development follows classical mineralisation pathways, inhibited by acidosis. It is known that the final mechanism of tissue mineralization involves three processes, all of which are highly pH dependent. Calcium interacts with phosphate in its trivalent form, but this step is inhibited by pyrophosphate, itself a source of phosphate when hydrolysed by alkaline phosphatase. Separately, matrix vesicles create nucleation sites and may indirectly disrupt vascular smooth muscle cells. Metabolic acidosis acts at every point to delay mineralization. The diuretic acetazolamide creates a sustained mild acidosis with some phosphate loss and, though usually ineffective in the experimental model, has been used with success in certain clinical conditions. We suggest that acetazolamide, well studied and tolerated, might inhibit progression of vascular calcification in subjects at risk through its dual action of lowering tissue pH and local phosphate concentration.

Probiotic administration of lactobacillus rhamnosus GR-1 attenuates atherosclerotic plaque formation in ApoE-/- mice fed with a high-fat diet.

OBJECTIVE: To investigate the effect of Lactobacillus rhamnosus GR-1 on atherosclerotic progression in apolipoprotein-E knockout (ApoE-/-) mice fed with a high-fat diet and the underlying mechanisms of its action. MATERIALS AND METHODS: Eight-week-old ApoE-/- mice were treated with Lactobacillus rhamnosus GR-1 daily for 12 weeks. ApoE-/- mice in the vehicle group and wild type (WT) mice were treated with normal saline. Serum lipid levels, histopathological analysis of the aorta, oxidative and inflammatory indexes and activation of the nuclear factor-kappa B (NF-κB) signaling pathway were examined. RESULTS: Compared to ApoE-/- mice in the vehicle group, no changes in body weight or serum lipid levels were found in ApoE-/- mice treated with Lactobacillus rhamnosus GR-1. However, the administration of GR-1 slowed down the development of atherosclerosis and reduced plaque formation. Additionally, GR-1 attenuated the development of oxidative stress and chronic inflammation in a dose-dependent manner in ApoE-/- mice fed a high-fat diet. Furthermore, in ApoE-/- mice treated with GR-1, GR-1 was demonstrated to have a role in inhibiting the translocation of NF-κB p65 from the cytoplasm to the nucleus and suppressing the degradation of IκB-α. CONCLUSIONS: We showed that the administration of GR-1 decreased atherosclerotic lesion size in ApoE-/- mice by reducing oxidative stress and inflammation. Additionally, the NF-κB signaling pathway might mediate these effects.

Long-Term Supplementation of Black Elderberries Promotes Hyperlipidemia, but Reduces Liver Inflammation and Improves HDL Function and Atherosclerotic Plaque Stability in Apolipoprotein E-Knockout Mice.

SCOPE: HDL particles are protective against atherosclerosis, but may become dysfunctional during inflammation and chronic disease progression. Anthocyanin-rich foods, such as the black elderberry, may improve HDL function and prevent disease development via antioxidant and/or anti-inflammatory effects. This study investigates the long-term consumption of black elderberry extract (BEE) on HDL function and atherosclerosis in apolipoprotein (apo) E-/- mice. METHODS AND RESULTS: ApoE-/- mice (n = 12/group) are fed a low-fat diet, supplemented with 0, 0.25%, or 1% (by weight) BEE (≈37.5-150 mg anthocyanins per kg body weight) for 24 weeks. Feeding 1% BEE increases total serum cholesterol (+31%) and non-HDL cholesterol (+32%) compared with the control diet. PON1 arylesterase (+32%) and lactonase (+45%) activities also increase with the 1% BEE diet. Both 0.25% BEE and 1% BEE diets strongly increase HDL cholesterol efflux capacity (CEC) by 64% and 85%, respectively. Further, BEE dose-dependently lowers serum liver enzymes and hepatic inflammatory gene expression. Although there is no change in neutral lipid accumulation in atherosclerotic lesions, BEE promotes connective tissue deposition in the aortic root. CONCLUSIONS: Chronic BEE supplementation in apoE-/- mice dose-dependently improves HDL function. Despite BEE promoting hyperlipidemia, which likely offsets HDL effects, BEE increases connective tissue content, suggesting improved atherosclerotic plaque stability.

Adherence to a Mediterranean diet is associated with the presence and extension of atherosclerotic plaques in middle-aged asymptomatic adults: The Aragon Workers' Health Study.

BACKGROUND: The Mediterranean diet (MeDi) is known to prevent cardiovascular events but the mechanisms mediating this association are not fully understood. OBJECTIVE: The objective of the study was to examine the association between MeDi adherence and the presence and extent of atherosclerotic plaques in carotid, femoral, and aorta territories and its relationship with risk factors in asymptomatic middle-aged adults. METHODS: Cross-sectional analysis of the Aragon Workers' Health Study, a cohort of 2588 subjects (94.9% men aged 51.3 ± 3.89 years) without previous cardiovascular history. Participants underwent carotid, femoral, and aorta ultrasound for the quantification of number and thickness of plaques and intima-media thickness. To estimate the participant's adherence to MeDi, we computed the Alternative MEDiterranean index (aMED). RESULTS: The overall aMED score was 4.19 ± 1.70, representing a moderate adherence to MeDi. aMED score was associated with the presence of plaque in femoral arteries (odds ratio highest vs lowest aMED score quartile: 0.63; 95% confidence interval: 0.48-0.83; P trend = .045) independently of risk factors and mediators. The strongest association between aMED quartiles and presence of plaque was found among smokers, both in femoral (0.39 [0.22-0.69]; P trend = .001) and in any territory (0.33 [0.14-0.79], P trend = .008). aMED was inversely associated with the number of plaques in all territories except for carotids. CONCLUSION: MeDi adherence showed a dose-dependent protective association with the presence, number, and thickness of plaques independent of other risk factors. The association was strongest for femoral arteries and among smokers.

Anti-Inflammatory Effects of the Mediterranean Diet in the Early and Late Stages of Atheroma Plaque Development.

Objective. To evaluate the long-term effects of a Mediterranean diet (MeDiet) intervention on the plasma concentrations of inflammatory and plaque stability-related molecules in elderly people at high risk for cardiovascular disease. Design and Setting. 66 participants from primary care centers affiliated with the Hospital Clinic of Barcelona were randomized into 3 groups: MeDiet plus extra virgin olive oil (EVOO) or nuts and a low-fat diet (LFD). At baseline and at 3 and 5 years, we evaluated the changes in the plasma concentrations of 24 inflammatory biomarkers related to the different stages of the atherosclerotic process by Luminex®. Results. At 3 and 5 years, both MeDiet groups showed a significant reduction of IL-6, IL-8, MCP-1, and MIP-1ß (P < 0.05; all) compared to LFD. IL-1ß, IL-5, IL-7, IL-12p70, IL-18, TNF-α, IFN-γ, GCSF, GMCSF, and ENA78 (P < 0.05; all) only decreased in the MeDiet+EVOO group and E-selectin and sVCAM-1 (P < 0.05; both) in the MeDiet+nuts group. Conclusions. Long-term adherence to MeDiet decreases the plasma concentrations of inflammatory biomarkers related to different steps of atheroma plaque development in elderly persons at high cardiovascular risk.

Low dose dietary nitrate improves endothelial dysfunction and plaque stability in the ApoE-/- mouse fed a high fat diet.

BACKGROUND: Nitric oxide (NO) is an important vascular signalling molecule. NO is synthesised endogenously by endothelial nitric oxide synthase (eNOS). An alternate pathway is exogenous dietary nitrate, which can be converted to nitrite and then stored or further converted to NO and used immediately. Atherosclerosis is associated with endothelial dysfunction and subsequent lesion formation. This is thought to arise due to a reduction in the bioavailability and/or bioactivity of endogenous NO. AIM: To determine if dietary nitrate can protect against endothelial dysfunction and lesion formation in the ApoE-/- mouse fed a high fat diet (HFD). METHODS AND RESULTS: ApoE-/- fed a HFD were randomized to receive (i) high nitrate (10mmol/kg/day, n=12), (ii) moderate nitrate (1mmol/kg/day, n=8), (iii) low nitrate (0.1mmol/kg/day, n=8), or (iv) sodium chloride supplemented drinking water (control, n=10) for 10 weeks. A group of C57BL6 mice (n=6) received regular water and served as a healthy reference group. At 10 weeks, ACh-induced vessel relaxation was significantly impaired in ApoE-/- mice versus C57BL6. Mice supplemented with low or moderate nitrate showed significant improvements in ACh-induced vessel relaxation compared to ApoE-/- mice given the high nitrate or sodium chloride. Plaque collagen expression was increased and lipid deposition reduced following supplementation with low or moderate nitrate compared to sodium chloride, reflecting increased plaque stability with nitrate supplementation. Plasma nitrate and nitrite levels were significantly increased in all three groups fed the nitrate-supplemented water. CONCLUSION: Low and moderate dose nitrate significantly improved endothelial function and atherosclerotic plaque composition in ApoE-/- mice fed a HFD.

[REGRESSION OF ATHEROSCLECROTIC LESIONS: MEDICAMENTAL AND ALIMENTARY FACTORS].

The article reports results of clinical studies aimed to elucidate the influence of medicines on the size and density of atherosclerotic plaques in the walls of coronary and cerebral arteries. The phenomenon of regression of atherosclerotic lesions in the survivors of Leningrad siege during a long period of starvation is analyzed. The influence of inhibitors of angiotensin-converting enzyme on apoptosis of smooth muscle and foam cells of atherosclerotic plaques in the sanological mechanisms of atherosclerosis is discussed. The concept of natural regression of atherosclerosis is formulated and the necessity of development of the methods for is pharmacological activation are formulated.

Direct association between diet and the stability of human atherosclerotic plaque.

Mediterranean diet has been suggested to explain why coronary heart disease mortality is lower in southern than northern Europe. Dietary habits can be revealed by isotope ratio mass spectrometry (IRMS) measurement of carbon (δ(13)C) and nitrogen (δ(15)N) in biological tissues. To study if diet is associated with human plaque stability, atherosclerotic plaques from carotid endarterectomy on 56 patients (21 Portuguese and 35 Swedish) were analysed by IRMS and histology. Plaque components affecting rupture risk were measured. Swedish plaques had more apoptosis, lipids and larger cores, as well as fewer proliferating cells and SMC than the Portuguese, conferring the Swedish a more rupture-prone phenotype. Portuguese plaques contained higher δ(13)C and δ(15)N than the Swedish, indicating that Portuguese plaques were more often derived from marine food. Plaque δ(13)C correlated with SMC and proliferating cells, and inversely with lipids, core size, apoptosis. Plaque δ(15)N correlated with SMC and inversely with lipids, core size and apoptosis. This is the first observational study showing that diet is reflected in plaque components associated with its vulnerability. The Portuguese plaques composition is consistent with an increased marine food intake and those plaques are more stable than those from Swedish patients. Marine-derived food is associated with plaque stability.

Molecular hydrogen stabilizes atherosclerotic plaque in low-density lipoprotein receptor-knockout mice.

Hydrogen (H(2)) attenuates the development of atherosclerosis in mouse models. We aimed to examine the effects of H(2) on atherosclerotic plaque stability. Low-density lipoprotein receptor-knockout (LDLR(-/-)) mice fed an atherogenic diet were dosed daily with H(2) and/or simvastatin. In vitro studies were carried out in an oxidized-LDL (ox-LDL)-stimulated macrophage-derived foam cell model treated with or without H(2). H(2) or simvastatin significantly enhanced plaque stability by increasing levels of collagen, as well as reducing macrophage and lipid levels in plaques. The decreased numbers of dendritic cells and increased numbers of regulatory T cells in plaques further supported the stabilizing effect of H(2) or simvastatin. Moreover, H(2) treatment decreased serum ox-LDL level and apoptosis in plaques with concomitant inhibition of endoplasmic reticulum stress (ERS) and reduction of reactive oxygen species (ROS) accumulation in the aorta. In vitro, like the ERS inhibitor 4-phenylbutyric acid, H(2) inhibited ox-LDL- or tunicamycin (an ERS inducer)-induced ERS response and cell apoptosis. In addition, like the ROS scavenger N-acetylcysteine, H(2) inhibited ox-LDL- or Cu(2+) (an ROS inducer)-induced reduction in cell viability and increase in cellular ROS. Also, H(2) increased Nrf2 (NF-E2-related factor-2, an important factor in antioxidant signaling) activation and Nrf2 small interfering RNA abolished the protective effect of H(2) on ox-LDL-induced cellular ROS production. The inhibitory effects of H(2) on the apoptosis of macrophage-derived foam cells, which take effect by suppressing the activation of the ERS pathway and by activating the Nrf2 antioxidant pathway, might lead to an improvement in atherosclerotic plaque stability.

[Expedience of application of a dietic therapy in treatment of purulent-septic diseases of soft tissues].

The results of investigation of the dietotherapy impact on the course of purulent-septic process in soft tissues were analyzed. There were operated 58 patients, to 38 of them a certain diet was prescribed. Immediate impact of the diet therapy on the wound process course was established, what was demonstrated by reduction of duration of the earning capacity loss in patients, who have followed a special diet, by 2.58 days.

The effects of the mediterranean diet on biomarkers of vascular wall inflammation and plaque vulnerability in subjects with high risk for cardiovascular disease. A randomized trial.

BACKGROUND: Adherence to the Mediterranean diet (MD) is associated with reduced morbidity and mortality due to cardiovascular disease. However, how the MD exerts its effects is not fully known. AIM: To assess the 12-month effects of two enhanced MDs compared to a low-fat diet on inflammatory biomarkers related to atherosclerosis and plaque vulnerability in a subcohort of the PREDIMED (Prevención con Dieta Mediterránea) study. METHODS: A total of 164 participants at high risk for cardiovascular disease were randomized into three diet groups: MD supplemented with 50mL/d of extra virgin olive oil (MD+EVOO) or 30 g/d of nuts (MD+Nuts) and a low-fat diet. Changes in classical cardiovascular risk factors, inflammatory biomarkers of atherosclerosis and plaque vulnerability were measured after 12 months of intervention. RESULTS: Compared to participants in the low-fat diet group, those receiving MD+EVOO and MD+Nuts showed a higher decrease in systolic (6mmHg) and diastolic (3mmHg) blood pressure (P = 0.02; both), as well as a reduction of 10% and 8% in LDL-cholesterol (P = 0.04), respectively. Patients in the MD+Nuts group showed a significant reduction of 34% in CD40 expression on monocyte surface compared to low-fat diet patients (P = 0.03). In addition, inflammatory biomarkers related to plaque instability such as C-reactive protein and interleukin-6 were reduced by 45% and 35% and 95% and 90% in the MD+EVOO and MD+Nuts groups, respectively (P<0.05; all) compared to the low-fat diet group. Likewise, sICAM and P-selectin were also reduced by 50% and 27%, respectively in the MD+EVOO group (P = 0.04) and P-selectin by 19% in MD+Nuts group (P = 0.04) compared to the low-fat diet group. CONCLUSIONS: Adherence to the MD is associated with an increase in serum markers of atheroma plaque stability which may explain, at least in part, the protective role of MD against ischemic heart disease. TRIAL REGISTRATION: www.controlled-trials.com ISRCTN35739639.

Effect of folic acid supplementation on levels of circulating Monocyte Chemoattractant Protein-1 and the presence of intravascular ultrasound derived virtual histology thin-cap fibroatheromas in patients with stable angina pectoris.

BACKGROUND: Virtual Histology Intravascular Ultrasound (VH-IVUS) may be used to detect early signs of unstable coronary artery disease. Monocyte Chemoattractant Protein-1 (MCP-1) is linked with coronary atherosclerosis and plaque instability and could potentially be modified by folic acid treatment. METHODS: In a randomized, prospective study, 102 patients with stable angina pectoris (SAP) received percutaneous coronary intervention and established medical treatment as well as either homocysteine-lowering folic acid/vitamin B12 (± B6) or placebo (± B6) for 1 year before VH-IVUS was performed. The presence of VH-Thin-Cap Fibroatheroma (VH-TCFA) in non-intervened coronary vessels was registered and serum levels of MCP-1 were measured. The patients were subsequently followed for incident myocardial infarction (MI). RESULTS: Patients treated with folic acid/vitamin B12 had a geometric mean (SD) MCP-1 level of 79.95 (1.49) versus 86.00 (1.43) pg/mL for patients receiving placebo (p-value 0.34). VH-TCFA lesions were present in 7.8% of patients and did not differ between intervention arms (p-value 0.47). Serum levels of MCP-1 were 1.46 (95% CI 1.12 to 1.92) times higher in patients with VH-TCFA lesions than in those without (p-value 0.005). Afterwards, patients were followed for median 2.1 years and 3.8% experienced a myocardial infarction (MI), which in post-hoc Cox regression analyses was independently predicted by both MCP-1 (P-value 0.006) and VH-TCFA (p-value 0.01). CONCLUSIONS: In patients with SAP receiving established medical treatment, folic acid supplementation is not associated with either presence of VH-TCFA or levels of MCP-1. MCP-1 is however associated with VH-TCFA, a finding corroborated by increased risk for future MI. ClinicalTrials.gov Identifier: NCT00354081.

ß-Carotene Attenuates Angiotensin II-Induced Aortic Aneurysm by Alleviating Macrophage Recruitment in Apoe(-/-) Mice.

Abdominal aortic aneurysm (AAA) is a common chronic degenerative disease characterized by progressive aortic dilation and rupture. The mechanisms underlying the role of α-tocopherol and ß-carotene on AAA have not been comprehensively assessed. We investigated if α-tocopherol and ß-carotene supplementation could attenuate AAA, and studied the underlying mechanisms utilized by the antioxidants to alleviate AAA. Four-months-old Apoe(-/-) mice were used in the induction of aneurysm by infusion of angiotensin II (Ang II), and were orally administered with α-tocopherol and ß-carotene enriched diet for 60 days. Significant increase of LDL, cholesterol, triglycerides and circulating inflammatory cells was observed in the Ang II-treated animals, and gene expression studies showed that ICAM-1, VCAM-1, MCP-1, M-CSF, MMP-2, MMP-9 and MMP-12 were upregulated in the aorta of aneurysm-induced mice. Extensive plaques, aneurysm and diffusion of inflammatory cells into the tunica intima were also noticed. The size of aorta was significantly (P = 0.0002) increased (2.24±0.20 mm) in the aneurysm-induced animals as compared to control mice (1.17±0.06 mm). Interestingly, ß-carotene dramatically controlled the diffusion of macrophages into the aortic tunica intima, and circulation. It also dissolved the formation of atheromatous plaque. Further, ß-carotene significantly decreased the aortic diameter (1.33±0.12 mm) in the aneurysm-induced mice (ß-carotene, P = 0.0002). It also downregulated ICAM-1, VCAM-1, MCP-1, M-CSF, MMP-2, MMP-9, MMP-12, PPAR-α and PPAR-γ following treatment. Hence, dietary supplementation of ß-carotene may have a protective function against Ang II-induced AAA by ameliorating macrophage recruitment in Apoe(-/-) mice.

Effects of dietary flaxseed on atherosclerotic plaque regression.

Dietary flaxseed can retard the progression of atherosclerotic plaques. However, it remains unclear whether these antiatherogenic effects extend to plaque regression. In the present study, the therapeutic potential of dietary flaxseed on atherosclerotic plaque regression and vascular contractile function was evaluated using a novel rabbit model. Rabbits were randomly assigned to receive either a regular diet for 12 wk (group I) or a 1% cholesterol-supplemented diet for 4 wk followed by a regular diet for 8 wk (group II). The remaining experimental animals were treated as in group II but were fed for an additional 14 wk with either a regular diet (group III) or a 10% flaxseed-supplemented diet (group IV). Animals in group II showed clear evidence of plaque growth stabilization. Their vessels also exhibited significantly lower norepinephrine-induced contraction and an impaired relaxation response to acetylcholine compared with animals in group I. Dietary flaxseed supplementation resulted in a significant ≈40% reduction in plaque formation (P = 0.033). Animals in both groups II and III displayed improved contraction and endothelium-dependent vessel relaxation. Dietary flaxseed is a valuable strategy to accelerate the regression of atherosclerotic plaques; however, flaxseed intervention did not demonstrate a clear beneficial effect on the vessel contractile response and endothelium-dependent vasorelaxation.

Diet intervention reduces uptake of αvß3 integrin-targeted PET tracer 18F-galacto-RGD in mouse atherosclerotic plaques.

BACKGROUND: Expression of α(v)ß(3) integrin has been proposed as a marker for atherosclerotic lesion inflammation. We studied whether diet intervention reduces uptake of α(v)ß(3) integrin-targeted positron emission tomography tracer (18)F-galacto-RGD in mouse atherosclerotic plaques. METHODS AND RESULTS: Hypercholesterolemic LDLR(-/-) ApoB(100/100) mice on high-fat diet for 4 months were randomized to further 3 months on high-fat diet (high-fat group, n = 8) or regular mouse chow (intervention group, n = 7). Intima-media ratio describing plaque burden was comparable between intervention and high-fat groups (2.0 ± 0.5 vs 2.3 ± 0.8, P = .5). Uptake of (18)F-galacto-RGD in the aorta was lower in the intervention than high-fat group (%ID/g 0.16 vs 0.23, P < .01). Autoradiography showed 35% lower uptake of (18)F-galacto-RGD in the atherosclerotic plaques in the intervention than high-fat group (P = .007). Uptake of (18)F-galacto-RGD in plaques correlated with uptake of (3)H-deoxyglucose and nuclear density, which was lower in the intervention than high-fat group (P = .01). Flow cytometry demonstrated macrophages expressing α(v) and ß(3) integrins in the aorta. CONCLUSIONS: Uptake of (18)F-galacto-RGD in mouse atherosclerotic lesions was reduced by lipid-lowering diet intervention. Expression of α(v)ß(3) integrin is a potential target for evaluation of therapy response in atherosclerosis.

Effects of linseed consumption for a short period of time on lipid profile and atherosclerotic lesions in rabbits fed a hypercholesterolaemic diet.

Linseed contains biologically active substances, such as lignans, fibres and linoleic acid, which are believed to provide cardioprotective effects. The objective of the present study was to assess the potential hypolipaemic, anti-atherogenic and anti-inflammatory effects of linseed consumption using an experimental animal model, with rabbits fed a hypercholesterolaemic diet (1 % cholesterol extracted from lyophilised egg). A total of twenty white male rabbits were selected and divided into two groups: group I (GI), control group, ten rabbits; group II (GII), ten rabbits. The animals were fed a hypercholesterolaemic diet for 56 d. For the GII diet, ground linseed was added from day 29 through to day 56. Animals underwent aortic arch and descending aorta dissection on day 56 for histological, morphometric and immunohistochemical analysis. At the end of the experiment, GII animals presented with lower levels of total cholesterol (TC, 10 068·3 v. 16 767·0 mg/l; P < 0·05) and lower levels of LDL-cholesterol (LDL-C; 10 743·2 v. 15 961·2 mg/l; P < 0·05) when compared with the GI control group. There was no significant difference in serum HDL-cholesterol and TAG between the two groups. Almost all animals exhibited type III atherosclerotic lesions in the descending aorta. There was no statistically significant difference between the intima area and the intima:media layer area ratio in both groups. There was no difference between the positive areas for vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 molecules between the groups. Linseed consumption showed hypolipaemic action by reducing LDL-C and TC levels; however, this cholesterol-lowering effect did not reduce the atherosclerotic lesions induced by a hypercholesterolaemic diet (1 % cholesterol) for a short period of time.

Atherosclerosis plaque heterogeneity and response to therapy detected by in vivo molecular imaging of matrix metalloproteinase activation.

UNLABELLED: Matrix metalloproteinases (MMPs) play a key role in the development of atherosclerosis and its complications. In vivo detection and quantification of MMP activation can help track the propensity to complications and response to therapy. We sought to establish an in vivo imaging approach for monitoring MMP activation in atherosclerotic mouse aorta and use it to assess the response to dietary modification. METHOD: Apolipoprotein-deficient mice were fed normal chow or a high-fat diet (HFD) for up to 3 mo or a HFD for 2 mo, followed by 1 mo on normal chow. Then they underwent micro-SPECT/CT, along with autoradiography and oil red O staining of tissues. RESULTS: After 3 mo of HFD, there was considerable atherosclerosis in the aorta. In vivo micro-SPECT/CT using RP782 (an (111)In-labeled tracer targeting activated MMPs) showed a heterogeneous pattern of tracer uptake along the aorta. Heterogeneity of RP782 uptake was confirmed by autoradiography, and specificity was demonstrated using excess unlabeled precursor. Tracer uptake quantified by micro-SPECT significantly correlated with uptake quantified by autoradiography. Comparison of oil red O staining with autoradiography demonstrated areas of discordance between plaque presence and tracer uptake. HFD withdrawal led to significant reduction in RP782 uptake beyond the effect on plaque area. MMP expression and macrophage infiltration were similarly heterogeneous along the aorta and significantly reduced after withdrawal from the HFD. Finally, RP782 uptake significantly correlated with aortic macrophage content. CONCLUSION: Molecular imaging of MMP activation reveals the heterogeneity of atherosclerotic plaques and is a useful tool for tracking plaque biology and response to therapy.

Simultaneous intake of oat bran and atorvastatin reduces their efficacy to lower lipid levels and atherosclerosis in LDLr-/- mice.

The present study aimed to investigate the effects of separate and simultaneous dietary intake of atorvastatin (ATO) and the soluble fiber oat bran on serum and hepatic lipid levels and the degree of atherosclerosis. Ninety female LDL-receptor-deficient (LDLr-/-) mice were fed a Western-type diet containing either low dose (0.0025%), high dose (0.01%) or no ATO, with or without oat bran (27%) (n=15 per group) for 16 weeks. Both ATO and oat bran were effective in reducing serum total cholesterol levels (low ATO: -5.48, high ATO: -9.12, oat bran: -3.82 mmol/l, compared to control (no ATO/no oat bran), all p<0.0001). When oat bran was added to a low dose ATO, the cholesterol-lowering effects of this combination were 50% smaller compared to the low dose ATO diet alone (between-group difference: 2.77 mmol/l, p=0.002), whereas total cholesterol decreased to a similar extent in the groups fed a high dose ATO, with or without oat bran (between-group difference: 1.10 mmol/l, p=0.21). Serum LDL- and HDL-cholesterol, triglycerides, hepatic lipid levels and atherosclerotic lesion development showed a similar pattern. In conclusion, the efficacy of oat bran and atorvastatin to lower lipid levels and atherosclerosis is reduced after simultaneous intake. We hypothesize that oat bran inhibits the intestinal absorption of atorvastatin, and consequently its cholesterol-lowering effects. The effects are likely dependent on the type of statin and dietary fiber, and on the relative timing of intake of the statin and the dietary fiber. Future studies should focus on these aspects to provide further insight into the exact mechanism of this food-drug interaction.