The oxidative modification hypothesis of atherosclerosis: The comparison of atherogenic effects on oxidized LDL and remnant lipoproteins in plasma

Influence on Adiposity and Atherogenic Lipaemia of Fatty Meals and Snacks in Daily Life

The present work reviewed the connections of changes in consumption of high-fat food with changes in adiposity and lipaemia in adults with overweight or obesity. Hyperlipaemia from higher fat meals and excessive adiposity contributes to atherogenic process. Low-fat diet interventions decrease body fat, lipaemia, and atherosclerosis markers. Inaccuracy of physical estimates of dietary fat intake remains, however, a limit to establishing causal connections. To fill this gap, tracking fat-rich eating episodes at short intervals quantifies the behavioural frequency suggested to measure (by regression of changes in real time) direct effects of this eating pattern on adiposity and atherogenic lipaemia. Such evidence will provide the basis for an approach focused on a sustained decrease in frequency of fatty meals or snacks to reduce obesity, hyperlipaemia, and atherosclerosis.

DC-SIGN and Toll-like receptor 4 mediate oxidized low-density lipoprotein-induced inflammatory responses in macrophages

The regulation of inflammatory responses by innate immune receptors is recognized as a crucial step in the development of atherosclerosis, although the precise molecular mechanisms remain to be elucidated. This study focused on illustrating the roles of dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN)- and Toll-like receptor 4 (TLR4)-regulated inflammatory responses in macrophages. We found that DC-SIGN expression levels were increased in macrophages of atherosclerotic plaques. Oxidized low-density lipoprotein (oxLDL) significantly enhanced DC-SIGN protein expression levels after a short-term exposure. Knockdown of DC-SIGN decreased expression and secretion of interleukin 1-β (IL1-β), monocyte chemo-attractant protein 1 (MCP-1), tumor necrosis factor-α (TNFα) and matrix metalloproteinase-9 (MMP-9). Immunofluorescence studies demonstrated that DC-SIGN and TLR4 co-localized in regions of the plaques. Moreover, DC-SIGN was co-expressed with TLR4 on the plasma membrane after oxLDL stimulation. The presence of an endogenous interaction and the results of the in vitro pull-down assays revealed that DC-SIGN binds directly with TLR4. We also present evidence that DC-SIGN mediates TLR4-regulated NFκB activation but not activation of p38 and JNK. Our results suggest an essential role of DC-SIGN/TLR4 signaling in macrophages in the pathogenesis of atherosclerosis.

Discordant Lipid Pattern and Carotid Atherosclerotic Plaque. Importance of Remnant Cholesterol

BACKGROUND:

Subjects with levels of non-HDL-C 30 mg/dL above those of LDL-C (lipid discordance) or with high remnant cholesterol levels could have a greater residual cardiovascular risk.

OBJECTIVES:

To determine the prevalence of lipid discordance in a primary prevention population and analyze the clinical variables associated with it; To investigate the association between lipid discordance and remnant cholesterol with the presence of carotid plaque.

METHODS:

Primary prevention patients without diabetes or lipid-lowering therapy were included. Regardless of the LDL-C level, we define "lipid discordance" if the non-HDL-C value exceeded 30 mg/dL that of LDL-C. Remnant cholesterol was calculated as total cholesterol minus HDL-C minus LDL-C when triglycerides were < 4.0 mmol/L. Ultrasound was used to assess carotid plaque occurrence. Multiple regression logistic models were performed.

RESULTS:

The study included 772 patients (mean age 52 ± 11 years, 66% women). The prevalence of lipid discordance was 34%. Male sex and body mass index were independently associated with discordant lipid pattern. The prevalence of carotid plaque was higher in subjects with lipid discordance (40.2% vs. 29.2, p = 0.002). The multivariate analysis showed that the discordant lipid pattern was associated with the greater probability of carotid plaque (OR 1.58, 95% CI 1.08-2.34, p = 0.02). Similarly, a significant association between calculated remnant cholesterol and carotid plaque was found.

CONCLUSION:

Lipid discordance and presence of a higher level of calculated remnant cholesterol are associated with subclinical atherosclerosis. Our findings could be used to improve the residual cardiovascular risk evaluation.

FUNDAMENTO:

Indivíduos com níveis de não HDL-C excedendo em 30 mg/dl aqueles de LDL-C (discordância lipídica) ou com altos níveis de colesterol remanescente poderiam ter maior risco cardiovascular residual.

OBJETIVOS:

determinar a prevalência de discordância lipídica em uma população de prevenção primária e analisar as variáveis clínicas com ela associadas; investigar a associação de discordância lipídica e colesterol remanescente calculado com a presença de placa carotídea.

MÉTODOS:

Pacientes de prevenção primária sem diabetes ou sem terapia hipolipemiante foram incluídos. Independentemente do nível de LDL-C, definiu-se "discordância lipídica" como um valor de não HDL-C excedendo em 30 mg/dl aquele de LDL-C. Calculou-se o colesterol remanescente como colesterol total menos HDL-C menos LDL-C na presença de triglicerídeos < 4,0 mmol/l. Usou-se ultrassom para avaliar a presença de placa carotídea. Modelos de regressão logística múltipla foram construídos.

RESULTADOS:

Este estudo incluiu 772 pacientes (idade média, 52 ± 11 anos; 66% mulheres). A prevalência de discordância lipídica foi de 34%. Sexo masculino e índice de massa corporal mostraram associação independente com padrão lipídico discordante. A prevalência de placa carotídea foi maior em indivíduos com discordância lipídica (40,2% vs. 29,2; p = 0,002). A análise multivariada mostrou associação do padrão lipídico discordante com maior probabilidade de placa carotídea (OR: 1,58; IC95%: 1,08-2,34; p = 0,02). Da mesma forma, identificou-se uma significativa associação entre colesterol remanescente calculado e placa carotídea.

CONCLUSÃO:

Discordância lipídica e presença de nível mais alto de colesterol remanescente calculado acham-se associados com aterosclerose subclínica. Nossos achados podem ser usados para aprimorar a avaliação de risco cardiovascular residual.

Remnant Cholesterol Elicits Arterial Wall Inflammation and a Multilevel Cellular Immune Response in Humans

OBJECTIVE

Mendelian randomization studies revealed a causal role for remnant cholesterol in cardiovascular disease. Remnant particles accumulate in the arterial wall, potentially propagating local and systemic inflammation. We evaluated the impact of remnant cholesterol on arterial wall inflammation, circulating monocytes, and bone marrow in patients with familial dysbetalipoproteinemia (FD).

APPROACH AND RESULTS

Arterial wall inflammation and bone marrow activity were measured using ¹⁸F-FDG PET/CT. Monocyte phenotype was assessed with flow cytometry. The correlation between remnant levels and hematopoietic activity was validated in the CGPS (Copenhagen General Population Study). We found a 1.2-fold increase of ¹⁸F-FDG uptake in the arterial wall in patients with FD (n=17, age 60±8 years, remnant cholesterol: 3.26 [2.07-5.71]) compared with controls (n=17, age 61±8 years, remnant cholesterol 0.29 [0.27-0.40]; P<0.001). Monocytes from patients with FD showed increased lipid accumulation (lipid-positive monocytes: Patients with FD 92% [86-95], controls 76% [66-81], P=0.001, with an increase in lipid droplets per monocyte), and a higher expression of surface integrins (CD11b, CD11c, and CD18). Patients with FD also exhibited monocytosis and leukocytosis, accompanied by a 1.2-fold increase of ¹⁸F-FDG uptake in bone marrow. In addition, we found a strong correlation between remnant levels and leukocyte counts in the CGPS (n=103 953, P for trend 5×10-276). In vitro experiments substantiated that remnant cholesterol accumulates in human hematopoietic stem and progenitor cells coinciding with myeloid skewing.

CONCLUSIONS

Patients with FD have increased arterial wall and cellular inflammation. These findings imply an important inflammatory component to the atherogenicity of remnant cholesterol, contributing to the increased cardiovascular disease risk in patients with FD.

Association of very Low-density Lipoprotein Cholesterol with All-cause and Cardiovascular Mortality in Peritoneal Dialysis

BACKGROUND/AIMS

Cardiovascular disease (CVD) is the leading cause of death in dialysis patients. Little is known about the relationship between very low-density lipoprotein cholesterol (VLDL-C) and cardiovascular mortality in these patients.

METHODS

A total of 1324 incident patients who began continuous ambulatory peritoneal dialysis (CAPD) therapy at our hospital between January 1, 2005, and September 30, 2014, with baseline serum VLDL-C values were investigated. The associations of the VLDL-C levels with all-cause and cardiovascular mortality were assessed.

RESULTS

The mean age of the cohort was 50.2 ± 14.8 years, and the mean VLDL-C level was 33.6 ± 18.0 mg/dl. One hundred sixty-five (12.5%) patients died during the study period. Multivariable models revealed that the high VLDL-C group was associated with significantly higher all-cause (HR, 2.08, 95% CI, 1.13 to 3.29, P = 0.002) and cardiovascular mortality (HR, 1.92, 95% CI, 1.18 to 4.29, P = 0.013) compared with the low VLDL-C group even after adjusting for various covariates. Using the VLDL-C level as a continuous variable, the hazard ratios (HRs) of all-cause and cardiovascular mortality associated with a 10-mg/dl increase in VLDL-C level were 1.12 (95% CI, 1.02 to 1.26, P = 0.025) and 1.11 (95% CI, 1.02 to 1.22, P = 0.029), respectively. VLDL-C was associated more strongly to all-cause (e.g., Akaike information criteria of 1990.205 vs. 1994.451) and cardiovascular (e.g., Akaike information criteria of 984.146 vs. 985.634) mortality than triglyceride (TG) levels.

CONCLUSIONS

An elevated VLDL-C level is an independent risk factor for all-cause and cardiovascular mortality in peritoneal dialysis (PD) patients.

Anti-atherosclerotic effect of housefly (Musca domestica) maggot-derived protein-enriched extracts by dampened oxidative stress in apolipoprotein E-deficient mice

Despitemany therapeutic advances, atherosclerosis remains the leading cause of morbidity and mortality in developed countries.

A Comparison of the Abdominal Fat Distribution and Coronary Risk Markers in Body Mass Index-matched Subjects with and without Fatty Liver

Objective The close relationship between fatty liver and metabolic syndrome suggests that individuals with fatty liver may have multiple coronary risk factors. In the present study, we investigated the relationships among fatty liver, abdominal fat distribution, and coronary risk markers. Methods and Results Eighty-seven pairs of men and 42 pairs of women who were matched for age and body mass index were enrolled in the present study. The obesity-related markers, abdominal fat distribution (examined by CT), and coronary risk markers were compared in subjects with and without fatty liver. The visceral fat area was significantly larger in the men with fatty liver than in the men without fatty liver. The plasma levels of triglyceride and low-density lipoprotein cholesterol (LDL-C), as well as the homeostasis model assessment-insulin resistance level, were higher in both males and females with fatty liver than in those without fatty liver, while the plasma levels of high-density lipoprotein cholesterol (HDL-C) and adiponectin were lower in the males and females with fatty liver. The plasma levels of apolipoprotein B, remnant-like particle cholesterol (RLP-C), and oxidized LDL were higher in men with fatty liver, but not in women with fatty liver. Conclusion Both males and females with fatty liver had lower insulin sensitivity, lower plasma levels of HDL-C and adiponectin, and higher triglyceride and LDL-C levels. However, the plasma levels of apolipoprotein B, RLP-C, and oxidized LDL were only higher and closely associated with fatty liver in men. Men with fatty liver had a higher risk of coronary disease than women with fatty liver.

Göttingen minipig model of diet-induced atherosclerosis: influence of mild streptozotocin-induced diabetes on lesion severity and markers of inflammation evaluated in obese, obese and diabetic, and lean control animals

Background

From a pharmacological perspective, readily-available, well-characterized animal models of cardiovascular disease, including relevant in vivo markers of atherosclerosis are important for evaluation of novel drug candidates. Furthermore, considering the impact of diabetes mellitus on atherosclerosis in human patients, inclusion of this disease aspect in the characterization of a such model, is highly relevant. The objective of this study was to evaluate the effect of mild streptozotocin-induced diabetes on ex- and in vivo end-points in a diet-induced atherosclerotic minipig model.

Methods

Castrated male Göttingen minipigs were fed standard chow (CD), atherogenic diet alone (HFD) or with superimposed mild streptozotocin-induced diabetes (HFD-D). Circulating markers of inflammation (C-reactive protein (CRP), oxidized low-density lipoprotein (oxLDL), plasminogen activator inhibitor-1, lipid and glucose metabolism were evaluated together with coronary and aortic atherosclerosis after 22 or 43 diet-weeks. Group differences were evaluated by analysis of variance for parametric data and Kruskal–Wallis test for non-parametric data. For qualitative assessments, Fisher’s exact test was applied. For all analyses, p < 0.05 was considered statistically significant.

Results

Overall, HFD and HFD-D displayed increased CRP, oxLDL and lipid parameters compared to CD at both time points. HFD-D displayed impaired glucose metabolism as compared to HFD and CD. Advanced atherosclerotic lesions were observed in both coronary arteries and aorta of HFD and HFD-D, with more advanced plaque findings in the aorta but without differences in lesion severity or distribution between HFD and HFD-D. Statistically, triglyceride was positively (p = 0.0039), and high-density lipoprotein negatively (p = 0.0461) associated with aortic plaque area.

Conclusions

In this model, advanced coronary and aortic atherosclerosis was observed, with increased levels of inflammatory markers, clinically relevant to atherosclerosis. No effect of mild streptozotocin-induced diabetes was observed on plaque area, lesion severity or inflammatory markers.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0670-2) contains supplementary material, which is available to authorized users.

Postprandial Dysmetabolism and Oxidative Stress in Type 2 Diabetes: Pathogenetic Mechanisms and Therapeutic Strategies

Postprandial dysmetabolism in type 2 diabetes (T2D) is known to impact the progression and evolution of this complex disease process. However, the underlying pathogenetic mechanisms still require full elucidation to provide guidance for disease prevention and treatment. This review focuses on the marked redox changes and inflammatory stimuli provoked by the spike in blood glucose and lipids in T2D individuals after meals. All the causes of exacerbated postprandial oxidative stress in T2D were analyzed, also considering the consequence of enhanced inflammation on vascular damage. Based on this in-depth analysis, current strategies of prevention and pharmacologic management of T2D were critically reexamined with particular emphasis on their potential redox-related rationale.

Elastic modulus of low-density lipoprotein as potential indicator of its oxidation

BACKGROUND

Evaluation of low-density lipoprotein oxidation is important in the risk assessment of cardiovascular disease. Atomic force microscope is widely used to evaluate the physical properties including stiffness on a single-particle scale. In this study, the effect of low-density lipoprotein oxidation on the low-density lipoprotein stiffness was investigated using an atomic force microscope.

METHODS

Isolated low-density lipoprotein particles with or without oxidation were densely bound to an Au substrate on mica, and then pressed and deformed by the atomic force microscope tip. The stiffness of each low-density lipoprotein particle was estimated as the elastic modulus obtained by the force curve analysis. Biochemical change of low-density lipoprotein due to oxidation was studied by electrophoresis.

RESULTS AND CONCLUSION

The elastic modulus of low-density lipoprotein particles ranged between 0.1 and 2 MPa. The oxidation of low-density lipoprotein increased the number of low-density lipoprotein particles with smaller elastic moduli, indicating the decrease in low-density lipoprotein stiffness. The elastic modulus of low-density lipoprotein might be potentially useful to evaluate low-density lipoprotein oxidation.

Synthesis of phenolic amides and evaluation of their antioxidant and anti-inflammatory activity in vitro and in vivo

15 phenolic amides (PAs) have been synthesized and examinedin vitrousing four tests: (1) prevention of Cu²⁺-induced human low-density lipoprotein oxidation, (2) scavenging of stable radicals, (3) anti-inflammatory activity, and (4) scavenging of superoxide radicals.

Postprandial lipemia as a cardiometabolic risk factor

High levels of fasting circulating triglycerides (TG) represent an independent risk factor for cardiovascular disease. In western countries, however, people spend most time in postprandial conditions, with continuous fluctuation of lipemia due to increased levels of TG-rich lipoproteins (TRLs), including chylomicrons (CM), very low density lipoproteins (VLDL), and their remnants. Several factors contribute to postprandial lipid metabolism, including dietary, physiological, pathological and genetic factors. The presence of coronary heart disease, type 2 diabetes, insulin resistance and obesity is associated with higher postprandial TG levels compared with healthy conditions; this association is present also in subjects with normal fasting TG levels. Increasing evidence indicates that impaired metabolism of postprandial lipoproteins contributes to the pathogenesis of coronary artery disease, suggesting that lifestyle modifications as well as pharmacological approaches aimed at reducing postprandial TG levels might help to decrease the cardiovascular risk.

Toll-like receptor 4 mediates inflammatory cytokine secretion in smooth muscle cells induced by oxidized low-density lipoprotein

Oxidized low-density lipoprotein (oxLDL)-regulated secretion of inflammatory cytokines in smooth muscle cells (SMCs) is regarded as an important step in the progression of atherosclerosis; however, its underlying mechanism remains unclear. This study investigated the role of toll-like receptor 4 (TLR4) in oxLDL-induced expression of inflammatory cytokines in SMCs both in vivo and in vitro. We found that the levels of TLR4, interleukin 1-β (IL1-β), tumor necrosis factor-α (TNFα), monocyte chemoattractant protein 1 (MCP-1) and matrix metalloproteinase-2 (MMP-2) expression were increased in the SMCs of atherosclerotic plaques in patients with femoral artery stenosis. In cultured primary arterial SMCs from wild type mice, oxLDL caused dose- and time-dependent increase in the expression levels of TLR4 and cytokines. These effects were significantly weakened in arterial SMCs derived from TLR4 knockout mice (TLR4-/-). Moreover, the secretion of inflammatory cytokines was blocked by TLR4-specific antibodies in primary SMCs. Ox-LDL induced activation of p38 and NFκB was also inhibited in TLR4-/- primary SMCs or when treated with TLR4-specific antibodies. These results demonstrated that TLR4 is a crucial mediator in oxLDL-induced inflammatory cytokine expression and secretion, and p38 and NFκB activation.

Statin therapy reduces oxidized low density lipoprotein level, a risk factor for stroke outcome

Introduction

Statins are reported to have anti-inflammatory and anti-oxidative effects aside from cholesterol-lowering effects. This study aimed to evaluate the effects of statin therapy on oxidized LDL (Ox-LDL) and the clinical outcome of patients with acute ischemic stroke (AIS).

Methods

This prospective study enrolled 120 patients with AIS divided in the statin (n = 55) and non-statin (n = 65) groups. Eighty sex- and age- matched participants were recruited as risk controls. Ox-LDL was measured using a monoclonal antibody-based enzyme-linked immune-sorbent assay at different time points after AIS. The clinical outcomes were analyzed between the statin and non-statin groups.

Results

Plasma Ox-LDL was significantly higher in stroke patients than in the controls (P < 0.001). Plasma Ox-LDL level was significantly reduced in the statin group on day 7 and day 30 compared to the non-statin group (P < 0.01). The plasma Ox-LDL positively correlated with serum total cholesterol, LDL-cholesterol, and hemoglobin A1c (HbA1c). Among the potential risk factors, only National Institutes of Health stroke scale (NIHSS) score and Ox-LDL level on admission were independently associated with 3-month outcome.

Conclusions

Our study demonstrates that statin therapy reduces plasma Ox-LDL level after AIS. Plasma Ox-LDL may be a more powerful predictor than serum LDL, high-sensitivity C-reactive protein or white blood cell counts for stroke outcome. Therefore, assay of plasma Ox-LDL should be added as a predictor among the panel of conventional biomarkers in stroke outcome.

Elevated Remnant Cholesterol Causes Both Low-Grade Inflammation and Ischemic Heart Disease, Whereas Elevated Low-Density Lipoprotein Cholesterol Causes Ischemic Heart Disease Without Inflammation

Background—

Elevated nonfasting remnant cholesterol and low-density lipoprotein (LDL) cholesterol are causally associated with ischemic heart disease (IHD), but whether elevated nonfasting remnant cholesterol and LDL cholesterol both cause low-grade inflammation is currently unknown.

Methods and Results—

We studied 60 608 individuals from the Copenhagen General Population Study, the Copenhagen City Heart Study, and the Copenhagen Ischemic Heart Disease study, of whom 10 668 had IHD diagnosed between 1977 and 2011. We genotyped for variants affecting levels of nonfasting remnant cholesterol, LDL cholesterol, C-reactive protein by CRP alleles, and C-reactive protein by IL6R alleles. Using a multidirectional mendelian randomization design, we investigated possible causal associations between the lipoproteins and C-reactive protein and between the lipoproteins and IHD. A 1-mmol/L(39 mg/dL) higher level of nonfasting remnant cholesterol was associated observationally with a 37% (95% confidence interval, 35–39) higher C-reactive protein level and causally with a 28% (95% confidence interval, 10–48) higher level. For LDL cholesterol, a 1-mmol/L (39-mg/dL) higher level was associated observationally with a 7% (95% confidence interval, 6–7) higher C-reactive protein level, but we found no causal association. Likewise, higher levels of C-reactive protein did not associate causally with elevated nonfasting remnant cholesterol or LDL cholesterol. Finally, the causal risk ratio for IHD for a 1-mmol/L (39-mg/dL) higher level was 3.3 (95% confidence interval, 2.1–5.2) for nonfasting remnant cholesterol and 1.8 (95% confidence interval, 1.5–2.2) for LDL cholesterol. The causal associations for remnant cholesterol were present even in those without diabetes mellitus and obesity.

Conclusions—

Elevated nonfasting remnant cholesterol is causally associated with low-grade inflammation and with IHD, whereas elevated LDL cholesterol is associated causally with IHD without inflammation.

Plasma adiponectin is a more specific marker of fatty liver than a marker of metabolic syndrome in Japanese men

BACKGROUND

The association of plasma cardiovascular risk markers and metabolic syndrome (MetS) with non-alcoholic fatty liver disease (NAFLD) has not been well defined.

METHODS

Japanese men (n = 809) had standard anthropometric measurements done, and had their liver fat quantitated by ultrasound. Three groups were identified: (1) normal controls without significant disease, (2) preliminary-metabolic syndrome (pre-MetS) cases and (3) MetS cases. Plasma adiponectin, high sensitivity-C reactive protein (hs-CRP), HOMA-IR, lipids, lipoproteins and liver enzymes were evaluated among the three groups.

RESULTS

The prevalence of fatty liver was 13% in controls, 39% in pre-MetS and 62% in MetS. Plasma adiponectin and high density lipoprotein cholesterol (HDL-C) were significantly decreased, and HOMA-IR, hs-CRP, TG, remnant lipoproteins (RLPs) and small dense-LDL-C (sd LDL-C) were significantly increased in subjects with fatty liver compared to those without fatty liver. Multivariate analyses of serum parameters associated with fatty liver revealed that adiponectin and hs-CRP were more strongly associated with the presence of fatty liver than waist circumference. However, HOMA-IR, HDL-C, TG, RLP-C, RLP-TG and sd LDL-C were more strongly associated with waist circumference than with fatty liver. Factor analysis revealed that adiponectin and HDL-C were linked to liver enzymes, lipoproteins and HOMA-IR associated with fatty liver, but not with waist circumference.

CONCLUSIONS

Adiponectin was found to be a more specific diagnostic marker for the presence of fatty liver regardless of MetS status, and was inversely correlated with liver enzyme concentrations. However, RLPs were found to be more specifically associated with the presence of MetS.

A randomized, open-label, multicentre study to evaluate plasma atherosclerotic biomarkers in patients with type 2 diabetes mellitus and arteriosclerosis obliterans when treated with Probucol and Cilostazol

Objectives

To evaluate the plasma atherosclerotic biomarkers in patients with type 2 diabetes mellitus (T2DM) and arteriosclerosis obliteran (ASO) when treated with Probucol plus Cilostazol in combination and individually.

Methods

In this open-label study, patients aged 40–75 years were randomized to receive conventional therapy alone, or with Cilostazol 100 mg bid, or with Probucol 250 mg bid, or with both in combination. Endpoints included changes in plasma biomarker and safety at 12 weeks.

Results

Of the 200 randomized patients, 165 for per-protocol and 160 for the safety (QTc intervals) were set, respectively. Probucol significantly reduced total cholesterol (P < 0.001), low-density lipoprotein cholesterol (LDL-C), (P = 0.01), and high-density lipoprotein cholesterol (HDL-C) (P < 0.001) compared with conventional therapy. Cilostazol was effective in increasing HDL-C (P = 0.002) and reducing triglycerides levels (P < 0.01) compared with conventional therapy. A trend towards significance was observed for the difference between conventional therapy alone and Probucol plus Cilostazol group for the change in oxidized low-density lipoprotein (Ox-LDL, P = 0.065). No significant effects on the majority of the remaining biomarkers were found across the treatment groups.

Conclusions

We have confirmed that Ox-LDL could be a possible plasma atherosclerotic biomarker among the evaluated biomarkers, which reflected the synergetic effect of Cilostazol plus Probucol in patients with T2DM and ASO shown previously in preclinical studies.

Influence of ezetimibe monotherapy on ischemia-modified albumin levels in hypercholesterolemic patients

Ischemia-modified albumin (IMA) is considered to be a novel biochemical marker for ischemic and atherosclerotic conditions. This study aimed to investigate the influence of ezetimibe monotherapy on circulating IMA levels in hypercholesterolemic patients. A total of 31 patients (mean age 65.7 years) received 10 mg of ezetimibe daily during a 12-week treatment period. The levels of low-density lipoprotein cholesterol and IMA were significantly reduced after ezetimibe treatment. The adjusted regression analyses revealed that the changes in the IMA levels were not significantly correlated with those of the other atherosclerotic risk markers, such as body mass index, blood pressure, glucose and lipid panels. The significant reduction of the IMA levels following ezetimibe treatment, which was independent of the reduction of low-density lipoprotein cholesterol levels, suggests that ezetimibe may improve the oxidative stress burden in hypercholesterolemic patients.

Triglyceride-rich lipoproteins in chronic kidney disease patients undergoing maintenance haemodialysis treatment

OBJECTIVE

Plasma triglyceride (TG) levels were reported to be high in chronic kidney disease (CKD) patients undergoing haemodialysis (HD) treatment. One of the atherogenic causes of hypertriglyceridemia is the increase in TG-rich lipoprotein remnants, which are equivalent to remnant-like particle cholesterol (RLP-C). Here, we compared the plasma levels of TG, a representative indicator of TG-rich lipoproteins and RLP-C, as well as the TG/RLP-C ratio between CKD patients undergoing HD and controls, in an effort to elucidate the atherogenicity of TG-rich lipoproteins in CKD patients on HD.

MATERIALS AND METHODS

Plasma lipid and apo(lipo)protein levels and the TG/RLP-C ratio were compared between 49 CKD patients undergoing HD and 627 controls. Blood sampling for lipid and apoprotein analysis was performed in a 12-h fasting state. Controls were divided into four subgroups according to TG level (from highest to lowest). RLP-C and apo(lipo)proteins were measured using the immunoprecipitation method and turbidimetric immunoassay, respectively. In addition, a comparison between HD patients and age-, gender-, and plasma TG level-matched controls was performed.

RESULTS

Plasma TG levels were 107 ± 70 (mean ± SD) mg/dl in HD patients and 115 ± 72 mg/dl in controls. Plasma RLP-C levels were 6.7 ± 4.5 mg/dl in HD patients and 4.6 ± 3.5 mg/dl in the controls (p < 0.0001). RLP-C levels decreased in descending order from the highest to the lowest TG group in controls. RLP-C levels were higher in HD patients than in controls with plasma TG levels of < 150 mg/dl (p < 0.0001). TG/RLP-C ratios were 19.0 ± 12.0 in HD patients and 25.9 ± 9.5 in controls (p < 0.0001). This ratio was significantly lower in HD patients than in all four TG subgroups. The comparison between HD patients and age-, gender-, plasma TG-matched controls revealed identical results.

CONCLUSION

Plasma RLP-C levels were high, and the TG/RLP-C ratio was low in CKD patients undergoing HD treatment. These findings indicate that total plasma TG-rich lipoprotein levels were not increased, but the distribution of plasma TG-rich lipoproteins were skewed towards remnant fractions in CKD patients undergoing HD treatment; these plasma TG-rich lipoproteins appear to be more atherogenic than those in controls.

Similarities and differences between the effects of EPA and DHA on markers of atherosclerosis in human subjects

We have reviewed effects of long chain (LC) n-3 PUFA on markers of atherosclerosis in human subjects with a focus on individual effects of EPA and DHA. Initial results from epidemiological studies suggested that LC n-3 PUFA from fish oils (FO) reduced incidence of CVD; those results have been confirmed in interventional studies. Dietary intervention with n-3 PUFA decreased fasting and postprandial TAG, number of remnant-like chylomicron particles, large VLDL, and total and small dense LDL particles. It increased mean size of LDL particles by increasing number of large and decreasing those of small dense particles. With some exceptions, n-3 PUFA decreased blood pressure (BP) and heart rate (HR), flow-mediated dilation (FMD) and plasma concentrations of inflammatory markers. n-3 PUFA also decreased circulating adhesion molecules and intima-media thickness (IMT) in some but not other studies. For IMT, results varied with the sex and artery being examined. EPA effects on FMD are endothelial cell dependent, while those of DHA seem to be endothelial cell independent. Individually, both EPA and DHA decreased TAG and inflammatory markers, but only DHA decreased HR, BP and number of small dense LDL particles. Results varied because of dose and duration of n-3 PUFA, EPA:DHA, health status of subjects and other reasons. Future studies are needed to determine optimal doses of EPA and DHA individually, their synergistic, additive or antagonistic effects, and to understand underlying mechanisms. In conclusion, n-3 PUFA decreased several risk factors for atherosclerosis without any serious adverse effects.

Effect of ezetimibe on remnant-like particle cholesterol in subjects with metabolic syndrome

OBJECTIVE

To investigate the influence of ezetimibe monotherapy on remnant-like particle cholesterol (RLP-C) in subjects with metabolic syndrome (MetS).

MATERIALS AND METHODS

Ezetimibe (10 mg/daily) was prescribed over a 12-week period for hypercholesterolemic subjects divided into groups with MetS (n = 28; male/female = 13/15; mean age 67 years) and without MetS (n = 22; male/female = 9/13; mean age 66 years). In the pre- and post-treatment phases, BMI, blood pressure and fasting blood levels of glucose, lipid panels and RLP-C were measured.

RESULTS

The group with MetS showed significantly higher RLP-C levels than the group without MetS [median level: 0.18 vs. 0.12 mmol/l (7.1 vs. 4.4 mg/dl), p < 0.01] in the pre-treatment phase. In the post-treatment phase, the low-density lipoprotein cholesterol levels were significantly reduced in both groups to a similar level (p < 0.001 in both), while there was a significantly greater reduction in RLP-C in the group with MetS than the group without MetS [median level: 0.12 vs. 0.11 mmol/l (4.8 vs. 4.1 mg/dl), p < 0.05]. This difference in RLP-C remained significant after adjusting for confounding factors.

CONCLUSION

Ezetimibe monotherapy may be associated with a greater reduction in RLP-C levels in subjects with MetS than in those without MetS.

The potential role of preventing atherosclerosis by induction of neonatal tolerance to VLDL

Induction of immune tolerance to ox-LDL could reduce atherosclerosis by modulation immune response. We suppose that very low density lipoprotein (VLDL) may have a similar role to ox-LDL in autoimmune response of atherosclerosis. In this study, neonatal rats were injected with ox-LDL, VLDL, or equal-volume saline, respectively. Vaccination with ox-LDL reduced the level of specific antibody, T cells proliferation response, and the level of endothelins. The method also had a tendency of reducing blood lipids. Vaccination with VLDL obviously reduced the level of specific antibody and T cells proliferation. Though there was also a tendency of reducing blood lipids and endothelins, the effect was less prominent than that with ox-LDL. We conclude that, although the effect was less obvious, vaccination with VLDL to induce neonatal tolerance had an effect on modulating immune response, protecting endothelial cells, and reducing blood lipids.

Postprandial lipoprotein metabolism: VLDL vs chylomicrons

Since Zilversmit first proposed postprandial lipemia as the most common risk of cardiovascular disease, chylomicrons (CM) and CM remnants have been thought to be the major lipoproteins which are increased in the postprandial hyperlipidemia. However, it has been shown over the last two decades that the major increase in the postprandial lipoproteins after food intake occurs in the very low density lipoprotein (VLDL) remnants (apoB-100 particles), not CM or CM remnants (apoB-48 particles). This finding was obtained using the following three analytical methods; isolation of remnant-like lipoprotein particles (RLP) with specific antibodies, separation and detection of lipoprotein subclasses by gel permeation HPLC and determination of apoB-48 in fractionated lipoproteins by a specific ELISA. The amount of the apoB-48 particles in the postprandial RLP is significantly less than the apoB-100 particles, and the particle sizes of apoB-48 and apoB-100 in RLP are very similar when analyzed by HPLC. Moreover, CM or CM remnants having a large amount of TG were not found in the postprandial RLP. Therefore, the major portion of the TG which is increased in the postprandial state is composed of VLDL remnants, which have been recognized as a significant risk for cardiovascular disease.

Pediatric nonalcoholic fatty liver disease, metabolic syndrome and cardiovascular risk

Nonalcoholic fatty liver disease (NAFLD) encompasses a range of liver histology severity and outcomes in the absence of chronic alcohol use. The mildest form is simple steatosis in which triglycerides accumulate within hepatocytes. A more advanced form of NAFLD, non-alcoholic steatohepatitis, includes inflammation and liver cell injury, progressive to cryptogenic cirrhosis. NAFLD has become the most common cause of chronic liver disease in children and adolescents. The recent rise in the prevalence rates of overweight and obesity likely explains the NAFLD epidemic worldwide. NAFLD is strongly associated with abdominal obesity, type 2 diabetes, and dyslipidemia, and most patients have evidence of insulin resistance. Thus, NAFLD shares many features of the metabolic syndrome (MetS), a highly atherogenic condition, and this has stimulated interest in the possible role of NAFLD in the development of atherosclerosis. Accumulating evidence suggests that NAFLD is associated with a significantly greater overall mortality than in the general population, as well as with increased prevalence of cardiovascular disease (CVD), independently of classical atherosclerotic risk factors. Yet, several studies including the pediatric population have reported independent associations between NAFLD and impaired flow-mediated vasodilatation and increased carotid artery intimal medial thickness-two reliable markers of subclinical atherosclerosis-after adjusting for cardiovascular risk factors and MetS. Therefore, the rising prevalence of obesity-related MetS and NAFLD in childhood may lead to a parallel increase in adverse cardiovascular outcomes. In children, the cardiovascular system remains plastic and damage-reversible if early and appropriate interventions are established effectively. Therapeutic goals for NAFLD should address nutrition, physical activity, and avoidance of smoking to prevent not only end-stage liver disease but also CVD.

Up-regulation of hepatic low-density lipoprotein receptor-related protein 1: a possible novel mechanism of antiatherogenic activity of hydroxymethylglutaryl-coenzyme A reductase inhibitor Atorvastatin and hepatic LRP1 expression

Low-density lipoprotein receptor-related protein 1 (LRP1) binds to apolipoprotein E and serves as a receptor for remnant lipoproteins in the liver, thus playing an important role in clearing these atherogenic particles. In this study, we investigated the effect of atorvastatin, a hydroxymethylglutaryl-coenzyme A reductase inhibitor, on hepatic LRP1 expression. We used HepG2 and Hep3B cells for in vitro study, and Otsuka Long-Evans Tokushima fatty and Sprague-Dawley rats for in vivo study. We used relatively high pharmacologic dose of atorvastatin in this study (in vitro, 0.5 μmol/L in culture media, for 48 hours; in vivo, 20 mg/[kg d], for 6 weeks). Atorvastatin increased LRP1 and low-density lipoprotein (LDL) receptor expression in HepG2 and Hep3B cells and induced hepatic LRP1 and LDL receptor expression in chow diet-fed Sprague-Dawley rats and high-fat diet-fed Otsuka Long-Evans Tokushima fatty rats. Atorvastatin decreased intracellular sterol level and increased the amount of the nuclear form of sterol response element-binding protein-2 (SREBP-2) in both HepG2 and Hep3B cells as well as in two animal models. Treatment of HepG2 cells with LDL increased intracellular sterol level and reduced LRP1, LDL receptor, and SREBP-2. When SREBP-2 in HepG2 cells was knocked down by small interfering RNA, the induction of LRP1 expression by atorvastatin did not take place. In conclusion, up-regulation of hepatic LRP1 might be a novel mechanism by which statin treatment decreases remnant lipoproteins. In addition, SREBP-2 acts as a mediator of atorvastatin-induced up-regulation of hepatic LRP1. Future studies using standard doses of atorvastatin in humans are needed to elucidate clinical relevance of these findings.

Cardiovascular Complications in CKD Patients: Role of Oxidative Stress

Starting with the early stages, patients with chronic kidney disease (CKD) experience higher burden of cardiovascular disease (CVD). Moreover, CVD complications are the major cause of mortality in CKD patients as compared with complications from chronic kidney failure. While traditional CVD risk factors, including diabetes, hypertension, hyperlipidemia, obesity, physical inactivity, may be more prevalent among CKD patients, these factors seem to underestimate the accelerated cardiovascular disease in the CKD population. Search for additional biomarkers that could explain the enhanced CVD risk in CKD patients has gained increasing importance. Although it is unlikely that any single nontraditional risk factor would fully account for the increased CVD risk in individuals with CKD, oxidative stress appears to play a central role in the development and progression of CVD and its complications. We will review the data that support the contribution of oxidative stress in the pathogenesis of CVD in patients with chronic kidney failure.

Particle size of apoB-48 carrying lipoproteins in remnant lipoproteins isolated from postprandial plasma

BACKGROUND

Particle size of apoB-48 carrying lipoproteins in remnant-like lipoprotein particles (RLP) in postprandial plasma has not been well characterized.

METHODS

Plasma lipids, lipoproteins and apolipoproteins in 12 healthy subjects were analysed after an oral fat load. RLP isolated by immunoaffinity gel from plasma of a normolipidaemic and a hyperlipidaemic subject in four hours after an oral fat load was fractionated by high-performance liquid chromatography (HPLC) and monitored by total cholesterol (TC), triglycerides (TG), apoB-48 and apoB-100.

RESULTS

TC, low-density lipoprotein (LDL)-C and apoB did not change after an oral fat load, while TG, RLP-C, RLP-TG and apoB-48 increased significantly in postprandial plasma. HPLC profiles monitored by TC and TG revealed that major lipoproteins increased in RLP after an oral fat load was VLDL size particles. The percentage of RLP-TG in total TG and the ratio of RLP-TG/RLP-C were significantly increased in four hours after an oral fat load compared with the fasting state (P < 0.01). RLP in four hours after an oral fat load fractionated by HPLC and monitored by TC, TG, apoB-48 and apoB-100 revealed that VLDL size or smaller particles were the major lipoproteins.

CONCLUSIONS

ApoB-48 carrying lipoproteins in RLP isolated from a normolipidaemic and a hyperlipidaemic subject after an oral fat load showed a similar particle size with apoB-100 carrying VLDL remnants. Therefore, the most apoB-48 carrying particles found in postprandial RLP can be classified as CM remnants. The majority of remnants in the postprandial state were not CM remnants, but VLDL remnants.

Pokkuri Death Syndrome; sudden cardiac death cases without coronary atherosclerosis in South Asian young males

Sudden death is one of the major concerns in forensic medicine. Especially when the deceased is a young subject without significant history, the case will be of major interest to the authorities. Sudden unexplained cardiac death has been known as "Pokkuri Death Syndrome" (PDS) in Japan, "Lai Tai" in Thailand, "Bangungut" in the Philippines, "Dream Disease" in Hawaii, and "Sudden Unexpected Nocturnal Death Syndrome" among South Asian immigrants in the USA. However, the clinical and pathological features of these sudden death cases, especially the characteristics of no coronary atherosclerosis, are surprisingly similar and mainly occur among Southeast Asian young males during sleep in the midnight. In this manuscript, we have reviewed the pathological characteristics and the possible mechanism of death in PDS cases, which were associated with significantly elevated remnant lipoproteins in plasma as revealed from our studies during the past 15 years in Japan. Although elevated plasma remnant lipoproteins have been known to be strongly atherogenic, coronary atherosclerosis was not observed in PDS cases. PDS cases were shown to be an interesting cardiovascular disease death discovered in forensic medicine research, which may suggest the difference between the occurrence of cardiovascular events and the severity of coronary atherosclerosis as separate factors. These observations in PDS cases suggest the possibility that the intervention could be more targeted to suppress the cardiovascular events rather than to slow down the progression of atherosclerosis, which is now most extensively targeted for the therapy of cardiovascular disease in Western countries.

Delayed postprandial metabolism of triglyceride-rich lipoproteins in obese young men compared to lean young men

BACKGROUND

Obesity, especially visceral obesity, has been known to affect lipoprotein metabolism, but it is not clear whether obesity in young, apparently healthy men is associated with postprandial triglyceride-rich lipoprotein (TRL) metabolism.

METHODS

Ten young normolipidemic, normoglycemic obese men (20.6 ± 0.5 y, BMI 27.5 ± 1.0 kg/m(2)) and 11 lean healthy men (22.1 ± 0.4 y, 21.2 ± 0.4 kg/m(2)) ingested OFTT cream (1g/kg body weight). Fasting and postprandial blood samples were obtained for up to 6h, and serum lipids and lipoproteins were analyzed.

RESULTS

The obese men with a fasting triglyceride (TG) in the normal range and not different from the fasting value of lean controls had a prolonged postprandial response, indicated by a significantly greater incremental areas under the curve in serum TG, TRL-TG, and remnant-like particle-cholesterol (RLP-C) compared with controls. Plasma glucose levels did not change during the test. Differences in serum insulin levels and homeostasis model assessment-insulin resistance (HOMA-IR) were not statistically significant between the two groups; however, trends toward higher levels were shown in obese young men.

CONCLUSIONS

The obese young men showed significantly delayed TRL metabolism compared to the lean young men after fat loading, even though the obese men were normolipidemic. These results suggest the possibility that early insulin resistance in the obese young men may have caused the decrease of lipoprotein lipase activity and induced delayed TRL metabolism. A fat loading test without carbohydrate may provide a useful tool for the detection of delayed postprandial TRL metabolism and early insulin resistance.

Reducing oxidized lipids to prevent cardiovascular disease

Despite significant success in reducing plasma cholesterol, especially low-density lipoprotein cholesterol, risks for cardiovascular disease (CVD) complications remain. Among these risks are circulating levels of oxidative modified lipoproteins, primarily oxidized low-density lipoproteins (oxLDL). The evidence supporting oxLDL as a potential target for therapeutic management to reduce metabolic complications and CVD events is reviewed in this report.

Artichoke leaf extract reduces oxidative stress and lipoprotein dyshomeostasis in rats fed on high cholesterol diet

Hypercholesterolemia and lipid peroxidation play complementary role in atherosclerosis. Artichoke leaf extract (ALE) is rich in natural antioxidants and has a cholesterol-reducing effect. However, there is no study investigating the effect of ALE on lipid levels and lipid peroxidation in experimental hypercholesterolemic conditions. Rats were fed on 4% (w/w) cholesterol and 1% (w/w) cholic acid supplemented diet for 1 month. ALE (1.5 g/kg/day) was given by gavage during the last 2 weeks. Serum lipid composition, malondialdehyde (MDA) and diene conjugate (DC) levels and plasma antioxidant activity (AOA) were measured. In addition, endogenous DC and copper-induced MDA levels were determined in apo B-containing lipoproteins (LDL+VLDL fraction). Serum cholesterol and triglyceride levels and the ratio of cholesterol to HDL-cholesterol decreased due to ALE treatment in rats fed on HC diet. Significant decreases in serum MDA and DC levels and increases in plasma AOA were detected in serum in ALE-treated hypercholesterolemic rats. Endogenous DC and copper-induced MDA levels were also lower in LDL+VLDL fraction due to ALE-treatment in hypercholesterolemic rats. Our results indicate that ALE may be useful for the prevention of hypercholesterolemia-induced pro-oxidant state in LDL+VLDL fraction and the reduction of increased serum cholesterol and triglyceride levels.

Effect of artichoke leaf extract on hepatic and cardiac oxidative stress in rats fed on high cholesterol diet

Hypercholesterolemia and lipid peroxidation play complementary roles in atherosclerosis. Artichoke (Cynara scolymus L., Asteraceae) leaf extract (ALE), rich in antioxidants, has cholesterol-reducing effect. We investigated the effect of ALE on serum and hepatic lipid levels and pro-oxidant-antioxidant balance in the liver and heart of hypercholesterolemic rats. Rats were fed on 4% (w/w) cholesterol and 1% cholic acid (w/w) supplemented diet for 1 month. ALE (1.5 g/kg/day) was given by gavage during the last 2 weeks. High cholesterol (HC) diet caused significant increases in serum and liver cholesterol and triglyceride levels. It increased malondialdehyde (MDA) and diene conjugate (DC) levels in both tissues. Hepatic vitamin E levels and hepatic and cardiac glutathione peroxidase (GSH-Px) activities decreased, but superoxide dismutase and glutathione transferase activities, glutathione, and vitamin C levels remained unchanged due to HC diet. Serum cholesterol and triglyceride levels and ratio of cholesterol to high-density lipoprotein (HDL)-cholesterol decreased in ALE plus HC-treated rats, but liver cholesterol and triglyceride levels remained unchanged. Significant decreases in hepatic and cardiac MDA and DC levels and increases in hepatic vitamin E and GSH-Px activities were observed in ALE-treated hypercholesterolemic rats. Our results indicate that ALE decreases serum lipids and hypercholesterolemia-induced pro-oxidant state in both tissues.

Fructose consumption: recent results and their potential implications

In addition to acquiring a better understanding of foods that may have intrinsic health benefits, increasing our knowledge of dietary components that may adversely impact health and wellness, and the levels of consumption at which these adverse effects may occur, should also be an important priority for the Foods for Health initiative. This review discusses the evidence that additional research is needed to determine the adverse effects of consuming added sugars containing fructose. Current guidelines recommend limiting sugar consumption in order to prevent weight gain and promote nutritional adequacy. However, recent data suggest that fructose consumption in human results in increased visceral adiposity, lipid dysregulation, and decreased insulin sensitivity, all of which have been associated with increased risk for cardiovascular disease and type 2 diabetes. A proposed model for the differential effects of fructose and glucose is presented. The only published study to directly compare the effects of fructose with those of commonly consumed dietary sweeteners, high fructose corn syrup and sucrose, indicates that high fructose corn syrup and sucrose increase postprandial triglycerides comparably to pure fructose. Dose-response studies investigating the metabolic effects of prolonged consumption of fructose by itself, and in combination with glucose, on lipid metabolism and insulin sensitivity in both normal weight and overweight/obese subjects are needed.

Kinetic study of low density lipoprotein oxidation by copper

Oxidation of Low Density Lipoprotein (LDL) is regarded as a key event in the development of atherosclerosis. The aim of this study was to investigate effect of various copper concentrations on LDL oxidation kinetic profile as a mechanism in atherosclerosis process. LDL was isolated from plasma and its oxidation with copper was investigated by monitoring the formation of conjugated dienes. Based on time course of the formation of conjugated diene was observed at concentrations of 0.5 to 10 µM copper, represented the conventional kinetics of LDL oxidation with an inhibition period followed by a propagation phase. In contrast, at concentrations of 20 to 50 µM copper, LDL oxidation proceeded after a negligibly short lag-time followed by a distinct propagation phase. At lower copper concentrations of about 0.5 µM, LDL oxidation can be combined in 4 consecutive oxidation phase. The increasing copper concentration (to 10 µM) lowered the first propagation and shortened the seconded inhibition period until they melted into one apparent kinetic phase. But in copper concentrations of about 20 to 50 µM, increasing copper concentration increased the first propagation and the second inhibition but lowered the second propagation phase. The results of this investigation on the copper dependence of the oxidation kinetics suggest that LDL contains two different copper binding sites. Copper bound to the low affinity binding sites with molar ratio of 200 to 500 of copper / LDL. These ions bound to the high affinity binding sites with molar ratio of copper / LDL of 5 to 100.