Improvement of coronary artery endothelial dysfunction with lipid-lowering therapy: heterogeneity of segmental response and correlation with plasma-oxidized low density lipoprotein

Oxidized phospholipids in cardiovascular disease

Prolonged or excessive exposure to oxidized phospholipids (OxPLs) generates chronic inflammation. OxPLs are present in atherosclerotic lesions and can be detected in plasma on apolipoprotein B (apoB)-containing lipoproteins. When initially conceptualized, OxPL-apoB measurement in plasma was expected to reflect the concentration of minimally oxidized LDL, but, surprisingly, it correlated more strongly with plasma lipoprotein(a) (Lp(a)) levels. Indeed, experimental and clinical studies show that Lp(a) particles carry the largest fraction of OxPLs among apoB-containing lipoproteins. Plasma OxPL-apoB levels provide diagnostic information on the presence and extent of atherosclerosis and improve the prognostication of peripheral artery disease and first and recurrent myocardial infarction and stroke. The addition of OxPL-apoB measurements to traditional cardiovascular risk factors improves risk reclassification, particularly in patients in intermediate risk categories, for whom improving decision-making is most impactful. Moreover, plasma OxPL-apoB levels predict cardiovascular events with similar or greater accuracy than plasma Lp(a) levels, probably because this measurement reflects both the genetics of elevated Lp(a) levels and the generalized or localized oxidation that modifies apoB-containing lipoproteins and leads to inflammation. Plasma OxPL-apoB levels are reduced by Lp(a)-lowering therapy with antisense oligonucleotides and by lipoprotein apheresis, niacin therapy and bariatric surgery. In this Review, we discuss the role of role OxPLs in the pathophysiology of atherosclerosis and Lp(a) atherogenicity, and the use of OxPL-apoB measurement for improving prognosis, risk reclassification and therapeutic interventions.

Endothelial Dysfunction and Pregnant COVID-19 Patients with Thrombophilia: A Narrative Review

Pregnancy with SARS-CoV-2 infection can raise the risk of many complications, including severe COVID-19 and maternal-fetal adverse outcomes. Additionally, endothelial damage occurs as a result of direct SARS-CoV-2 infection, as well as immune system, cardiovascular, and thrombo-inflammatory reactions. In this narrative review, we focus on endothelial dysfunction (ED) in pregnancy, associated with obstetric complications, such as preeclampsia, fetal growth retardation, gestational diabetes, etc., and SARS-CoV-2 infection in pregnant women that can cause ED itself and overlap with other pregnancy complications. We also discuss some shared mechanisms of SARS-CoV-2 pathophysiology and ED.

Lipoprotein(a) and carotid intima-media thickness in children with familial hypercholesterolaemia in the Netherlands: a 20-year follow-up study

BACKGROUND

Elevated lipoprotein(a) and familial hypercholesterolaemia are both independent risk conditions for cardiovascular disease. Although signs of atherosclerosis can be observed in children with familial hypercholesterolaemia, it is unknown whether elevated lipoprotein(a) is an additional risk factor for atherosclerosis in these young patients. Therefore, we aimed to assess the contribution of lipoprotein(a) concentrations to arterial wall thickening (as measured by carotid intima-media thickness) in children with familial hypercholesterolaemia who were followed up into adulthood.

METHODS

We conducted a 20-year follow-up study of 214 children (aged 8-18 years) with heterozygous familial hypercholesterolaemia who were randomly assigned in a statin trial in Amsterdam (Netherlands) between Dec 7, 1997, and Oct 4, 1999. At baseline, and at 2, 10, and 20 years thereafter, blood samples were taken and carotid intima-media thickness was measured. Linear mixed-effects models were used to evaluate the association between lipoprotein(a) and carotid intima-media thickness during follow-up. We adjusted for sex, age, corrected LDL-cholesterol, statin use, and BMI.

FINDINGS

Our study population comprised 200 children who had a carotid intima-media thickness measurement and a measured lipoprotein(a) concentration from at least one visit available. Mean age at baseline was 13·0 years (SD 2·9), 106 (53%) children were male, and 94 (47%) were female. At baseline, median lipoprotein(a) concentration was 18·5 nmol/L (IQR 8·7-35·5) and mean carotid intima-media thickness was 0·4465 mm (SD 0·0496). During follow-up, higher lipoprotein(a) concentrations contributed significantly to progression of carotid intima-media thickness (β adjusted 0·0073 mm per 50 nmol/L increase in lipoprotein(a) [95% CI 0·0013-0·0132]; p=0·017).

INTERPRETATION

Our findings suggest that lipoprotein(a) concentrations contribute significantly to arterial wall thickening in children with familial hypercholesterolaemia who were followed-up until adulthood, suggesting that lipoprotein(a) is an independent and additional risk factor for early atherosclerosis in those already at increased risk. Lipoprotein(a) measurement in young patients with familial hypercholesterolaemia is crucial to identify those at potentially highest risk for cardiovascular disease.

FUNDING

Silence Therapeutics.

Serum cholesterol loading capacity of macrophages is regulated by seropositivity and C-reactive protein in rheumatoid arthritis patients

OBJECTIVE

Excessive cholesterol accumulation in macrophages is the pivotal step underlying atherosclerotic plaque formation. We here explore factors in the serum of patients with RA, and mechanisms through which they interact with and influence cholesterol loading capacity (CLC) of macrophages.

METHODS

In a cross-sectional observational cohort of 104 patients with RA, CLC was measured as intracellular cholesterol content in human THP-1-derived macrophages after incubation with patient serum. Low-density lipoprotein (LDL) oxidation was measured in terms of oxidized phospholipids on apoB100-containing particles (oxPL-apoB100). Antibodies against oxidized LDL (anti-oxLDL), proprotein convertase subtilisin/Kexin type-9 (PCSK9) and high-sensitivity CRP were also quantified. All analyses adjusted for atherosclerotic cardiovascular disease (ASCVD) risk score, obesity, total LDL, statin use, age at diagnosis, and anti-oxLDL IgM.

RESULTS

OxPL-apoB100, anti-oxLDL IgG and PCSK9 were positively associated with CLC (all P < 0.020). OxPL-apoB100 directly influenced CLC only in dual RF- and ACPA-positive patients [unstandardized b (95% bootstrap CI)=2.08 (0.38, 3.79)]. An indirect effect of oxPL-apoB100 on CLC through anti-oxLDL IgG increased, along with level of CRP [index of moderated mediation = 0.55 (0.05-1.17)]. CRP also moderated yet another indirect effect of oxPL-apoB100 on CLC through upregulation of PCSK9, but only among dual-seropositive patients [conditional indirect effect = 0.64 (0.13-1.30)].

CONCLUSION

Oxidized LDL can directly influence CLC in dual-seropositive RA patients. Two additional and independent pathways-via anti-oxLDL IgG and PCSK9-may mediate the effects of oxPL-apoB100 on CLC, depending on CRP and seropositivity status. If externally validated, these findings may have clinical implications for cardiovascular risk prevention.

Possibility as role of ginseng and ginsenosides on inhibiting the heart disease of COVID-19: A systematic review

Coronavirus has been spreading rapidly around the world since it broke out in China in 2019. Respiratory diseases caused by coronavirus infection cause various diseases ranging from asymptomatic subclinical infections to severe pneumonia and cardiovascular complications, leading to death. In this regard, natural products are being studied to prevent various diseases caused by COVID-19. In current review, we would like to present mechanisms related to the inhibition of heart disease in ginseng and ginsenoside against SARS-CoV-2. In many previous studies, ginseng and ginsenoside are known to have antioxidant, blood flow improvement, improvement of vascular and heart function, blood pressure control, suppression of myocardial infarction and heart failure, and antiarrhythmia. Therefore, ginseng and ginsenoside have a possibility to suppress cardiovascular complications caused by COVID-19. Many of research provide evidence for ginseng and ginsenoside as treatments for the risk of cardiovascular complications. However, in this review, more specific contents on the proposition of the efficacy of ginseng and ginsenoside for COVID-19 should be presented. Therefore, we hope that researches to reduce cardiovascular complications of ginseng and ginsenoside for COVID-19 should be presented to reduce mortality for COVID-19.

Lipoprotein oxidation may underlie the paradoxical association of low cholesterol with coronary atherosclerotic risk in rheumatoid arthritis

OBJECTIVE

To compare coronary plaque burden, proatherogenic cytokines, oxidized low-density lipoprotein (oxLDL), anti-oxLDL antibodies, lipoprotein(a)-cholesterol, and their relationships in patients with rheumatoid arthritis with low-density lipoprotein cholesterol (LDL-C)<1.8 mmol/L versus ≥1.8 mmol/L. Also, to study differences in inflammation and proprotein convertase subtilisin/kexin type-9 (PCSK9), which impacts LDL clearance, in patients with low versus high LDL-C.

METHODS

Computed tomography angiography evaluated coronary plaque (noncalcified, partially calcified, fully calcified, and high-risk plaque) in 150 patients from a single-center observational cohort. Ox-LDL, anti-oxLDL IgG, lipoprotein(a)-cholesterol, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), interleukin-6, tumor necrosis factor-α (TNF-α) and PCSK9 were measured. Analyses adjusted for Framingham general cardiovascular risk score, statin use, and high-density lipoprotein cholesterol.

RESULTS

Patients with LDL-C<1.8 mmol/L versus ≥1.8 mmol/L demonstrated: 1) higher likelihood of per-segment plaque (adjusted-OR = 1.67 [95%CI = 1.10-2.55], p = 0.017) and high-risk plaque presence (adjusted-OR 2.78 [95%CI = 1.06-7.29], p = 0.038); 2) greater anti-oxLDL titers (p = 0.020), which positively associated with TNF-α and likelihood of noncalcified, partially calcified and high-risk plaque presence only in patients with LDL-C<1.8 mmol/L (all p-for-interaction≤0.046); 3) increased lipoprotein(a)-cholesterol content (10.33% [8.11-12.54] versus 6.68% [6.10-7.25], p < 0.001), which positively associated with oxLDL (p < 0.001) and anti-oxLDL (p = 0.036); 4) higher interleukin-6 and PCSK9. No differences in CRP, ESR, or oxLDL were observed.

CONCLUSION

RA patients with LDL-C<1.8 mmol/L had more coronary plaque, higher anti-oxLDL titers and anti-oxLDL associated with plaque only in this group. It is possible the observed paradoxical association of low LDL-C with greater atherosclerosis may be related to higher production of the oxidation-prone lipoprotein(a)-cholesterol and anti-oxLDL antibodies, resulting in increased vascular LDL uptake and plaque formation.

Could Statin Therapy Be Useful in Patients With Coronavirus Disease 2019 (COVID-19)?

Acute respiratory distress syndrome (ARDS), resulting from an exaggerated inflammatory response, is the main cause of death from the coronavirus disease 2019 (COVID-19). Apart from respiratory infection, COVID-19 patients can develop cardiovascular disorders such as myocardial injury and myocarditis, pericarditis, cardiac arrest and arrhythmias, cardiomyopathy, heart failure, coagulation abnormalities and thrombosis. Statins can beneficially affect inflammation, oxidative stress, coagulation, thrombosis, angiotensin converting enzyme receptor, lipid rafts, and endothelial function. In this narrative review, we provide a critical overview of the current evidence and future perspectives on the use of statins to modulate the severity, duration and complications of COVID-19 through their pleiotropic properties.

COVID-19 and Acute Coronary Syndromes: From Pathophysiology to Clinical Perspectives

Acute coronary syndromes (ACS) are frequently reported in patients with coronavirus disease 2019 (COVID-19) and may impact patient clinical course and mortality. Although the underlying pathogenesis remains unclear, several potential mechanisms have been hypothesized, including oxygen supply/demand imbalance, direct viral cellular damage, systemic inflammatory response with cytokine-mediated injury, microvascular thrombosis, and endothelial dysfunction. The severe hypoxic state, combined with other conditions frequently reported in COVID-19, namely sepsis, tachyarrhythmias, anemia, hypotension, and shock, can induce a myocardial damage due to the mismatch between oxygen supply and demand and results in type 2 myocardial infarction (MI). In addition, COVID-19 promotes atherosclerotic plaque instability and thrombus formation and may precipitate type 1 MI. Patients with severe disease often show decrease in platelets count, higher levels of d-dimer, ultralarge von Willebrand factor multimers, tissue factor, and prolongation of prothrombin time, which reflects a prothrombotic state. An endothelial dysfunction has been described as a consequence of the direct viral effects and of the hyperinflammatory environment. The expression of tissue factor, von Willebrand factor, thromboxane, and plasminogen activator inhibitor-1 promotes the prothrombotic status. In addition, endothelial cells generate superoxide anions, with enhanced local oxidative stress, and endothelin-1, which affects the vasodilator/vasoconstrictor balance and platelet aggregation. The optimal management of COVID-19 patients is a challenge both for logistic and clinical reasons. A deeper understanding of ACS pathophysiology may yield novel research insights and therapeutic perspectives in higher cardiovascular risk subjects with COVID-19.

Endothelial dysfunction in COVID-19: Current findings and therapeutic implications

Coronavirus disease 2019 (COVID-19) increases the risk of several non-pulmonary complications such as acute myocardial injury, renal failure or thromboembolic events. A possible unifying explanation for these phenomena may be the presence of profound endothelial dysfunction and injury. This review provides an overview on the association of endothelial dysfunction with COVID-19 and its therapeutic implications. Endothelial dysfunction is a common feature of the key comorbidities that increase risk for severe COVID-19 such as hypertension, obesity, diabetes mellitus, coronary artery disease or heart failure. Preliminary studies indicate that vascular endothelial cells can be infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and evidence of widespread endothelial injury and inflammation is found in advanced cases of COVID-19. Prior evidence has established the crucial role of endothelial cells in maintaining and regulating vascular homeostasis and blood coagulation. Aggravation of endothelial dysfunction in COVID-19 may therefore impair organ perfusion and cause a procoagulatory state resulting in both macro- and microvascular thrombotic events. Angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs) and statins are known to improve endothelial dysfunction. Data from smaller observational studies and other viral infections suggests a possible beneficial effect in COVID-19. Other treatments that are currently under investigation for COVID-19 may also act by improving endothelial dysfunction in patients. Focusing therapies on preventing and improving endothelial dysfunction could improve outcomes in COVID-19. Several clinical trials are currently underway to explore this concept.

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New evidence implicates endothelial dysfunction in the pathophysiology of COVID-19.

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It may explain complications such as multi-organ damage or thrombotic events.

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Targeted interventions such as RAS inhibitors or statins may improve outcomes.

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Studies on interventions that affect endothelial dysfunction are underway in COVID-19.

Therapeutic Antibody Against Phosphorylcholine Preserves Coronary Function and Attenuates Vascular 18F-FDG Uptake in Atherosclerotic Mice

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Phosphorylcholine is a pro-inflammatory epitope in atherogenic oxidized phospholipids.

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This study investigated effects of a novel monoclonal IgG1 antibody against PC on vascular function and atherosclerotic inflammation.

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Treatment with phosphorylcholine antibody preserved coronary flow reserve and decreased uptake of ¹⁸F-FDG in atherosclerotic lesions in hypercholesterolemic mice.

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Noninvasive imaging techniques represent translational tools to assess the efficacy of phosphorylcholine-targeted therapy on coronary artery function and atherosclerosis.

This study showed that treatment with a therapeutic monoclonal immunoglobulin-G1 antibody against phosphorylcholine on oxidized phospholipids preserves coronary flow reserve and attenuates atherosclerotic inflammation as determined by the uptake of ¹⁸F-fluorodeoxyglucose in atherosclerotic mice. The noninvasive imaging techniques represent translational tools to assess the efficacy of phosphorylcholine-targeted therapy on coronary artery function and atherosclerosis in clinical studies.

The Significance of Oxidized Low-Density Lipoprotein in Body Fluids as a Marker Related to Diseased Conditions

Oxidatively modified low-density lipoprotein (oxLDL) is known to be involved in various diseases, including cardiovascular diseases. The presence of oxLDL in the human circulatory system and in atherosclerotic lesions has been demonstrated using monoclonal antibodies. Studies have shown the significance of circulating oxLDL in various systemic diseases, including acute myocardial infarction and diabetic mellitus. Several different enzyme-linked immunosorbent assay (ELISA) procedures to measure oxLDL were utilized. Evidence has been accumulating that reveals changes in oxLDL levels under certain pathological conditions. Since oxLDL concentration tends to correlate with low-density lipoprotein (LDL)-cholesterol, the ratio of ox-LDL and LDL rather than oxLDL concentration alone has also been focused. In addition to circulating plasma, LDL and oxLDL are found in gingival crevicular fluid (GCF), where the ratio of oxLDL to LDL in GCF is much higher than in plasma. LDL and oxLDL levels in GCF show an increase in diabetic patients and periodontal patients, suggesting that GCF might be useful in examining systemic conditions. GCF oxLDL increased when the teeth were affected by periodontitis. It is likely that oxLDL levels in plasma and GCF could reflect oxidative stress and transfer efficacy in the circulatory system.

Effect of vildagliptin versus glibenclamide on endothelial function and arterial stiffness in patients with type 2 diabetes and hypertension: a randomized controlled trial

AIMS

Several trials have reported that dipeptidyl peptidase-4 (DPP-4) inhibitors, used to treat type 2 diabetes (T2DM), improve endothelial function. The current study investigated the effects of vildagliptin, a DPP-4 inhibitor, compared to glibenclamide on endothelial function, arterial stiffness, and blood pressure in patients with T2DM and hypertension.

METHODS

Patients aged over 35 years with T2DM and hypertension, but without cardiovascular disease, were randomly allocated to treatment with vildagliptin (n = 25) or glibenclamide (n = 25). Both groups took metformin. Endothelial function was evaluated by peripheral artery tonometry (Endo-PAT 2000) to calculate the reactive hyperemia index (RHI) and arterial stiffness. Primary outcome was change in the RHI after 12 weeks of treatment. Twenty-four-hour non-invasive ambulatory blood pressure monitoring was performed using a Mobil-O-Graph^® 24-h PWA monitor. Arterial stiffness was assessed using the augmentation index corrected for 75 bpm (AIx75), pulse wave velocity (PWV) and central systolic blood pressure (cSBP).

RESULTS

There were no changes in the RHI in the vildagliptin group (before 2.35 ± 0.59; after 2.24 ± 0.60; p value = NS) or in the glibenclamide group (before 2.36 ± 0.52; after 2.34 ± 0.50; p value = NS), with no differences between groups (p value = NS). There was also no difference between vildagliptin and glibenclamide treatment in respect to AIx75 (p value = NS), cSBP (p value = NS) or PWV (p value = NS).

CONCLUSIONS

Vildagliptin and glibenclamide similarly do not change the endothelial function and arterial stiffness after 12 weeks of treatment in diabetic and hypertensive patients without cardiovascular disease. Thus, vildagliptin has a neutral effect on vascular function.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02145611, registered on 11 Jun 2013.

Oxidized lipids: not just another brick in the wall 1

Over the past decade, there has been intense investigation in trying to understand the pathological role that oxidized phospholipids play in cardiovascular disease. Phospholipids are targets for oxidation, particularly during conditions of excess free radical generation. Once oxidized, they acquire novel roles uncharacteristic of their precursors. Oxidized phosphatidylcholines have an important role in multiple physiological and pathophysiological conditions including atherosclerosis, neurodegenerative diseases, lung disease, inflammation, and chronic alcohol consumption. Circulating oxidized phosphatidylcholine may also serve as a clinical biomarker. The focus of this review, therefore, will be to summarize existing evidence that oxidized phosphatidylcholine molecules play an important role in cardiovascular pathology.

Lipoprotein Apheresis Acutely Reverses Coronary Microvascular Dysfunction in Patients With Severe Hypercholesterolemia

OBJECTIVES

This study evaluated whether lipoprotein apheresis produces immediate changes in resting perfusion in subjects with severe hypercholesterolemia, and whether there is a difference in the response between peripheral and coronary microcirculations.

BACKGROUND

Lipoprotein apheresis is used in patients with severe hypercholesterolemia to reduce plasma levels of low-density lipoprotein cholesterol.

METHODS

Quantitative contrast-enhanced ultrasound perfusion imaging of the myocardium at rest and skeletal muscle at rest and during calibrated contractile exercise was performed before and immediately after lipoprotein apheresis in 8 subjects with severe hypercholesterolemia, 7 of whom had a diagnosis of familial hypercholesterolemia. Myocardial perfusion imaging was also performed in 14 normal control subjects. Changes in myocardial work and left ventricular function were assessed by echocardiography. Ex vivo ovine coronary and femoral artery ring tension assays were assessed in the presence of pre- and post-apheresis plasma.

RESULTS

Apheresis acutely decreased low-density lipoprotein cholesterol (234.9 ± 103.2 mg/dl vs. 67.1 ± 49.5 mg/dl; p < 0.01) and oxidized phospholipid on apolipoprotein B-100 (60.2 ± 55.2 nmol/l vs. 47.0 ± 24.5 nmol/l; p = 0.01), and acutely increased resting myocardial perfusion (55.1 [95% confidence interval: 77.2 to 73.1] IU/s vs. 135 [95% confidence interval: 81.2 to 189.6] IU/s; p = 0.01), without changes in myocardial work. Myocardial longitudinal strain improved in those subjects with reduced pre-apheresis function. Skeletal muscle perfusion at rest and during contractile exercise was unchanged by apheresis. Acetylcholine-mediated dilation of ex vivo ovine coronary but not femoral arteries was impaired in pre-apheresis plasma and was completely reversed in post-apheresis plasma.

CONCLUSIONS

Lipoprotein apheresis produces an immediate improvement in coronary microvascular function, which increases myocardial perfusion and normalizes endothelial-dependent vasodilation. These changes are not observed in the periphery. (Acute Microvascular Changes With LDL Apheresis; NCT02388633).

Effect of short-term hazelnut consumption on DNA damage and oxidized LDL in children and adolescents with primary hyperlipidemia: a randomized controlled trial

Children with primary hyperlipidemia are prone to develop premature atherosclerosis, possibly associated with increased oxidative stress. Nutritional therapy is the primary strategy in the treatment of hyperlipidemia and associated conditions. Dietary interventions with bioactive-rich foods, such as nuts, may contribute to the modulation of both lipid profile and the oxidative/antioxidant status. Our study aimed to assess the impact of a dietary intervention with hazelnuts on selected oxidative stress markers in children and adolescents with primary hyperlipidemia. A single-blind, 8-week, randomized, controlled, three-arm, parallel-group study was performed. Children and adolescents diagnosed with primary hyperlipidemia (n=60) received dietary guidelines and were randomized into three groups: group 1 received hazelnuts with skin (HZN+S), and group 2 hazelnuts without skin (HZN-S), at equivalent doses (15-30 g/day, based on body weight); group 3 (controls) received only dietary recommendations (no nuts). At baseline and after 8 weeks, plasma oxidized low-density lipoprotein (ox-LDL) concentrations, oxidative levels of DNA damage in PBMCs and potential correlation with changes in serum lipids were examined. A reduction of endogenous DNA damage by 18.9%±51.3% (P=.002) and 23.1%±47.9% (P=.007) was observed after HZN+S and HZN-S, respectively. Oxidatively induced DNA strand breaks decreased by 16.0%±38.2% (P=.02) following HZN+S treatment. Ox-LDL levels did not change after HZN+S intervention but positively correlated with total cholesterol and LDL cholesterol. A short-term hazelnut intervention improves cell DNA protection and resistance against oxidative stress but not ox-LDL in hyperlipidemic pediatric patients. The trial was registered at ISRCTN.com, ID no. ISRCTN12261900.

Endothelial Dysfunction of Patients with Peripheral Arterial Disease Measured by Peripheral Arterial Tonometry

Objective. Endothelial dysfunction plays a key role in atherosclerotic disease. Several methods have been reported to be useful for evaluating the endothelial dysfunction, and we investigated the endothelial dysfunction in patients with peripheral arterial disease (PAD) using peripheral arterial tonometry (PAT) test in this study. Furthermore, we examined the factors significantly correlated with PAT test. Methods. We performed PAT tests in 67 patients with PAD. In addition, we recorded the patients' demographics, including comorbidities, and hemodynamical status, such as ankle brachial pressure index (ABI). Results. In a univariate analysis, the ABI value (r = 0.271, P = 0.029) and a history of cerebrovascular disease (r = 0.208, P = 0.143) were found to significantly correlate with PAT test, which calculated the reactive hyperemia index (RHI). In a multivariate analysis, only the ABI value significantly and independently correlated with RHI (β = 0.254, P = 0.041). Conclusion. This study showed a significant correlation between RHI and ABI. The PAT test is a useful tool for evaluating not only endothelial dysfunction but also the hemodynamical state in patients with PAD.

Novel immune assay for quantification of plasma protective capacity against oxidized phospholipids

Aim: Oxidized phospholipids (OxPL) are the major pathogenic component of oxidized low-density lipoproteins (OxLDL). Endogenous anti-OxPL activity, defined as the ability to neutralize adverse effects of oxidized lipids, may have biomarker potential. Methods & results: Using two anti-OxPL monoclonal antibodies (commercial mAB-E06 and custom mAB-509) we developed a novel ELISA that measures the global capacity of plasma to inactivate OxPL. Preincubation of OxLDL with plasma inhibits its binding of anti-OxPL mABs. This phenomenon (‘masking’) reflects anti-OxPL plasma activity. A pilot clinical application of the assay revealed reduced anti-OxPL activity in hypertension, coronary artery disease, acute coronary syndrome and diabetes. Conclusion: Inadequate anti-OxPL protection may contribute to cardiovascular disease and have biomarker potential in conditions associated with abnormal lipid peroxidation.

The relationship between oxidised LDL, endothelial progenitor cells and coronary endothelial function in patients with CHD

Objective

The balance between coronary endothelial dysfunction and repair is influenced by many protective and deleterious factors circulating in the blood. We studied the relationship between oxidised low-density lipoprotein (oxLDL), circulating endothelial progenitor cells (EPCs) and coronary endothelial function in patients with stable coronary heart disease (CHD).

Methods

33 patients with stable CHD were studied. Plasma oxLDL was measured using ELISA, coronary endothelial function was assessed using intracoronary acetylcholine infusion and EPCs were quantified using flow cytometry for CD34⁺/KDR⁺ cells.

Results

Plasma oxLDL correlated positively with the number of EPCs in the blood (r=0.46, p=0.02). There was a positive correlation between the number of circulating EPCs and coronary endothelial function (r=0.42, p=0.04). There was no significant correlation between oxLDL and coronary endothelial function.

Conclusions

Plasma levels of oxLDL are associated with increased circulating EPCs in the blood of patients with CHD, which may reflect a host-repair response to endothelial injury. Patients with stable CHD had a high prevalence of coronary endothelial dysfunction, which was associated with lower numbers of circulating EPCs, suggesting a mechanistic link between endothelial dysfunction and the pathogenesis of atherosclerosis.

Twelve-week randomized study to compare the effect of vildagliptin vs. glibenclamide both added-on to metformin on endothelium function in patients with type 2 diabetes and hypertension

BACKGROUND

Vildagliptin, a DPP-4 inhibitor widely used for the treatment of type 2 diabetes mellitus (T2DM), shows beneficial effects on endothelial function. This study aims to evaluate the effect of vildagliptin on endothelial function and arterial stiffness in patients with T2DM and hypertension.

METHODS

Fifty over 35-year-old patients with T2DM and hypertension, without cardiovascular disease, will be randomly allocated to two groups: group 1 will receive vildagliptin added-on to metformin and group 2, glibenclamide added-on to metformin. Biochemical tests (glycemia, glycated hemoglobin, total cholesterol, high-density lipoprotein cholesterol, triglycerides, creatinine, alanine aminotransferase, ultrasensitive C-reactive protein, and microalbuminuria), 24-h non-invasive ambulatory blood pressure monitoring, and assessment of endothelial function and arterial stiffness will be performed in both groups before and after 12 weeks of treatment. The endothelial function will be assessed by peripheral arterial tonometry, which measures the reactive hyperemia index (vasodilation), and arterial stiffness will be evaluated by applanation tonometry. All analysis will be performed using SPSS Statistical Software. For all analysis, a 2-sided P < 0.05 will be considered statistically significant.

RESULTS

The study started in December 2013 and patient recruitment is programed until October 2015. The expected results are that vildagliptin will improve the endothelial function in patients with T2DM and hypertension compared to glibenclamide treatment, independently of glycemic control.

CONCLUSIONS

It is expected that this DPP-4 inhibitor will improve endothelial function in patients with T2 DM.

TRIAL REGISTRATION

Clinical Trials NCT02145611, registered on 11 Jun 2013.

Coronary Endothelium-Dependent Vasoreactivity and Atheroma Volume in Subjects With Stable, Minimal Angiographic Disease Versus Non–ST-Segment–Elevation Myocardial Infarction

Background—

Epicardial plaque burden and endothelial function are recognized predictors of coronary events. We aimed to investigate mechanistic relationships between atheroma volume and endothelial function in patients with non–ST-segment–elevation myocardial infarction (NSTEMI) using intravascular ultrasound.

Methods and Results—

In coronary vessels of patients with near-normal or minimal angiographic disease (n=23) and NSTEMI (n=24), intravascular ultrasound-derived measures (percent atheroma volume), arterial remodeling index, and segmental lumen volumes were performed in contiguous 5-mm epicardial segments. Repeat intravascular ultrasound imaging was performed after consecutive 5-minute intracoronary infusions (vehicle solution, 0.30 μg/min and 0.60 μg/min intracoronary salbutamol) to measure changes in segmental lumen volume (endothelium-dependent function). Male sex, diabetes mellitus, smoking, higher triglycerides, and lower high-density lipoprotein cholesterol were more prevalent in the NSTEMI group. Patients with NSTEMI demonstrated greater segmental percent atheroma volume (40.4±12 versus 27.5±14%, P<0.001), remodeling index (1.2 [1.0–1.5] versus 1.0 [0.9–1.0], P<0.001), and displayed less endothelium-dependent vasomotion (% change segmental lumen volume: 2.1±0.89 versus 5.1±0.89%, P=0.02) compared to patients with minimal angiographic disease. No significant difference in endothelial function between both groups was observed when controlling for plaque burden. Multivariate analysis for change in segmental lumen volume identified percent atheroma volume (β=−0.18, P=0.0004), high-sensitivity C-reactive protein >2 mg/L (β=−3.1, P=0.03), diabetes mellitus (β=−6.9, P<0.0001), low-density lipoprotein cholesterol levels (β=−0.04, P=0.01), and smoking (β=–3.2, P=0.01) as independent associates.

Conclusions—

Although coronary endothelial vasoreactivity is blunted in the setting of NSTEMI, this is a reflection of the greater volume of atherosclerosis and cardiovascular risk factors. Thus, the relationship between coronary endothelium-dependent vasomotor reactivity and atheroma volume remains constant irrespective of the nature of the clinical presentation.

Oxidized phospholipids on apoB-100-containing lipoproteins: a biomarker predicting cardiovascular disease and cardiovascular events

Oxidative stress is a well-known etiologic factor in the development of cardiovascular disease. Oxidation of lipoproteins, and in particular of low density lipoprotein, is a necessary if not obligatory mechanism for the generation of macrophage-derived foam cells, the first major initiating factor in the development of an atherosclerotic plaque. Oxidation of lipoproteins does not result in the generation of a single, defined molecular species, but of a variety of oxidation-specific epitopes, such as oxidized phospholipids and malondialdehyde-lysine epitopes. Unique monoclonal antibodies have been developed to bind these well-defined epitopes, and have been used in in vitro assays to detect them on circulating lipoproteins present in plasma. This article will summarize the accumulating clinical data of one oxidation-specific biomarker, oxidized phospholipids (OxPL) on apoB-100 lipoproteins. Elevated levels of OxPL/apoB predict the presence and progression of coronary, femoral and carotid artery disease, are increased following acute coronary syndromes and percutaneous coronary intervention, and predict the development of death, myocardial infarction, stroke and need for revascularization in unselected populations. OxPL/apoB levels are independent of traditional risk factors and the metabolic syndrome, and enhance the risk prediction of the Framingham Risk Score. The OxPLs measured in this assay reflect the biological activity of the most atherogenic lipoprotein(a) (Lp(a)) particles, reflected in patients with high plasma Lp(a) levels with small apo(a) isoforms. The predictive value of OxPL/apoB is amplified by Lp(a) and phospholipases such as lipoprotein-associated phospholipase A(2) and secretory phospholipase A(2), which are targets of therapy in clinical trials. This assay has now been validated in over 10,000 patients and efforts are underway to make it available to the research and clinical communities.

Noninvasive assessment of endothelial function in clinical practice

In the fight against cardiovascular diseases, preventive strategies are becoming the focus of attention. One of these strategies proposes to identify individuals who are at a high risk of developing cardiovascular disease. Endothelial dysfunction could improve patient risk stratification and the implementation of preventive strategies. In this review we focus on noninvasive techniques that have recently become available to assess endothelial function: flow-mediated vasodilation as measured by ultrasound of the brachial artery, pulse wave analysis, and finger plethysmography during postischemic hyperemia. We describe the basic principles, the main protocols to perform these techniques, and their clinical value based on the scientific evidence.

Circulating oxidized LDL: a biomarker and a pathogenic factor

PURPOSE OF REVIEW

Oxidized LDL (oxLDL) contributes to many atherogenic steps in the vascular wall, but the significance of oxLDL in circulating blood remains unclear. Recent progress in procedures for measuring both human and murine oxLDL has provided growing evidence of the importance of circulating oxLDL.

RECENT FINDINGS

Circulating oxLDL is elevated in patients with advanced atherosclerosis, such as coronary heart disease and ischemic stroke, and also reflects early atherosclerotic changes and metabolic disorders including diabetes and obesity. In-vitro exposure to oxLDL increased mononuclear cell nuclear factor-kappaB activity, suggesting a pathogenic role of circulating oxLDL in exacerbation of oxidative stress. In addition, adenoviral administration of secreted scavenger receptor-A1, which functions as a decoy, suppresses foam cell formation in LDL receptor-deficient mice via a blockade of modified LDL incorporation into macrophages. Furthermore, when lectin-like oxLDL receptor-1 was ectopically expressed in the liver, circulating oxLDL was reduced, resulting in complete prevention of atherosclerotic progression in apolipoprotein E-deficient mice. Thus, circulating oxLDL impacts atherogenic formation.

SUMMARY

The roles of circulating oxLDL in atherosclerotic pathogenesis are now attracting considerable attention. OxLDL removal from circulating blood is a promising therapeutic strategy against atherosclerosis.

Comparison effect of atorvastatin (10 versus 80 mg) on biomarkers of inflammation and oxidative stress in subjects with metabolic syndrome

Metabolic syndrome (MS), characterized by low-grade inflammation, confers an increased risk for cardiovascular disease. Statins, in addition to having lipid-lowering effects, have pleiotropic effects and decrease biomarkers of inflammation and oxidative stress. The Treating to New Target Study showed a greater decrease in low-density lipoprotein (LDL) cholesterol and cardiovascular events with atorvastatin 80 mg versus 10 mg in patients with MS with coronary heart disease. However, part of this benefit could be caused by the greater pleiotropic effects of the higher dose of atorvastatin. The dose-response effect of atorvastatin on biomarkers of inflammation and oxidative stress has not been investigated in subjects with MS. Thus, the dose-response effect of atorvastatin on biomarkers of inflammation (high-sensitivity C-reactive protein [hs-CRP], matrix metalloproteinase-9, and nuclear factor-kappaB [NF-kB] activity) and oxidative stress (oxidized LDL, urinary nitrotyrosine, F2-isoprostanes, and monocyte superoxide release) was tested in a randomized double-blind clinical trial in subjects with MS. Seventy subjects were randomly assigned to receive placebo or atorvastatin 10 or 80 mg/day for 12 weeks. A strong dose-response (atorvastatin 10 compared with 80 mg, p <0.05) was observed for changes in total, LDL (32% and 44% reduction), non-high-density lipoprotein (28% and 40% reduction), and oxidized LDL cholesterol (24% and 39% reduction) at atorvastatin 10 and 80 mg, respectively. Hs-CRP, matrix metalloproteinase-9, and NF-kB significantly decreased in the 80-mg atorvastatin group compared with baseline. In conclusion, this randomized trial of subjects with MS showed the superiority of atorvastatin 80 mg compared with its 10-mg dose in decreasing oxidized LDL, hs-CRP, matrix metalloproteinase-9, and NF-kB activity.

Oxidative stress and endothelial dysfunction in vascular disease

In response to physiologic stimuli, endothelial cells dynamically regulate arterial vascular tone by producing vasodilators and vasoconstrictors. Risk factors for atherosclerosis, such as diabetes, smoking, hypercholesterolemia, and hypertension, interfere with this response, promoting endothelial dysfunction and atherosclerosis. This review explores whether oxidative stress might be a common feature of both endothelial dysfunction and atherosclerosis. Using biomarkers to assess endothelial function might provide insights into the pathways for oxidative stress in vascular disease. However, currently available markers of oxidative stress and endothelial function are unsuitable for routine clinical use because they are too expensive and inadequately validated. Thus, there is a need to develop and validate new markers that could be used to both measure oxidative stress and monitor therapies that specifically interrupt oxidative pathways in vascular tissue. Such markers might eventually help to identify susceptible individuals at a stage when cardiovascular complications could be prevented.

Measurement of plasma oxidized low-density lipoprotein and its clinical implications

Oxidized low-density lipoprotein (OxLDL) has been shown to exist in human circulating plasma. Several groups including ours have developed methods for immunologically measuring OxLDL, which have been applied to several clinical, both cross-sectional and prospective, studies. These data clearly show that OxLDL levels correlate well with the severity of cardiovascular diseases. In particular, recent observations suggest that plasma OxLDL levels could be a useful marker for predicting future cardiovascular events; however, substantial differences exist among the different methods of OxLDL measurement. To evaluate the clinical data on circulating OxLDL, a proper understanding of the similarity, differences, and limitation of the methods is needed. This paper summarizes the characteristics of the methods used and recent clinical findings.

High-dose atorvastatin is associated with impaired myocardial angiogenesis in response to vascular endothelial growth factor in hypercholesterolemic swine

OBJECTIVES

The disappointing results of myocardial angiogenic therapy have been attributed, in part, to endothelial dysfunction present in patients with coronary disease. Statins have established proendothelial properties but seem to have dose-dependent effects on angiogenesis. We investigated the functional and molecular effects of high-dose atorvastatin on vascular endothelial growth factor-induced myocardial angiogenesis in hypercholesterolemic swine.

METHODS

Yucatan miniswine (20-30 kg) were fed either a normal (ND group, n = 8) or high-cholesterol diet, with (HC-ATOR group, n = 8) or without (HC group, n = 8) atorvastatin (3 mg x kg(-1) x d(-1)), for 13 weeks. Chronic ischemia was induced by ameroid constrictor placement around the circumflex artery, followed 3 weeks later by perivascular vascular endothelial growth factor administration (2 microg over 4 weeks) with a sustained release osmotic pump. Microvessel relaxation responses, myocardial perfusion, and myocardial expression of angiogenic mediators were assessed 4 weeks later.

RESULTS

Hypercholesterolemic swine demonstrated impaired microvessel relaxation to vascular endothelial growth factor (P < .01 vs ND group) and adenosine diphosphate (P < .001 vs ND group), which was normalized in the HC-ATOR group. After perivascular vascular endothelial growth factor administration, collateral-dependent myocardial perfusion was significantly increased in the ND group but decreased in both the HC and HC-ATOR groups (both P < .01 vs the ND group). The animals in the HC-ATOR group demonstrated increased myocardial expression of the antiangiogenic protein endostatin and increased Akt phosphorylation without significant changes in Akt and endothelial nitric oxide synthase expression.

CONCLUSIONS

Atorvastatin treatment reverses hypercholesterolemia-induced endothelial dysfunction without appreciable improvements in collateral-dependent myocardial perfusion in response to vascular endothelial growth factor treatment. Increased myocardial endostatin expression and chronic Akt activation, associated with atorvastatin therapy, might account for the lack of improvement in the angiogenic response to vascular endothelial growth factor therapy.

Oxidative biomarkers in the diagnosis and prognosis of cardiovascular disease

Oxidative damage to lipids and proteins is an important component of atherosclerotic cardiovascular disease (CVD). Studies of oxidation-related molecules are helping to define atherosclerotic mechanisms, and measurements of circulating levels of specific oxidant compounds may improve cardiovascular risk assessment. The present article reviews accumulating data of selected oxidative biomarkers that support their role in providing diagnostic and/or prognostic information. For example, plasma levels of the enzyme myeloperoxidase, which generates the strong oxidizing agent hypochlorous acid, have been found to be correlated with risk for myocardial infarction and endothelial dysfunction. Elevated levels of lipoprotein-associated phospholipase A(2) are associated with coronary artery disease (CAD) and stroke. Oxidized phospholipids play an important role in atherosclerosis. Recent studies measuring circulating levels of oxidized phospholipids have suggested a strong association with CAD, plaque disruption, and response to 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor ("statin") therapy. Isoprostanes correlate strongly with cardiovascular risk factors, but their role in risk prediction is less well defined. Future studies are expected to clarify the role of oxidative biomarkers in the diagnosis and prognosis of CVD and to determine their value in specific clinical populations.

Measures of Oxidative Stress

Development of in vivo markers of oxidative stress that are sensitive, specific, reliable, and accurate in reflecting underlying atherosclerotic disease states and prediction of cardiovascular risk and clinical events will be invaluable in the future in clinical medicine. Oxidized low-density lipoprotein (OxLDL) and isoprostanes are emerging plasma biomarkers that hold promise for cardiovascular risk prediction. This article describes the pathophysiology of OxLDL and isoprostanes as potential biomarkers, the rationale behind development of methods to measure OxLDL and isoprostanes, and a detailed description of current methodologies, including advantages and disadvantages of available assays. Clinical investigations consisting of epidemiological, case-control, and prospective studies are reviewed to elucidate the role of these biomarkers in reflecting pathophysiology and risk prediction.

Elevated hydroperoxide levels as a prognostic predictor of mortality in a cohort of patients with cardiovascular disease

The aim of this study was to evaluate whether hydroperoxide levels, an index of oxidative stress, predict cardiac and total death in patients with cardiovascular disease. Serum hydroperoxide levels were measured in 157 consecutive inpatients, followed during a mean follow-up of 20+/-0.3 months. Elevated oxidative stress resulted in an independent predictors for cardiac death, suggesting that hydroperoxide evaluation could provide an adjunctive estimate in the evaluation of prognosis in the cardiovascular clinical setting.

C-Reactive Protein and Other Emerging Blood Biomarkers to Optimize Risk Stratification of Vulnerable Patients

Several emerging plasma biomarkers may ultimately prove useful in risk stratification and prognosis of cardiovascular disease. The clinical utility of these biomarkers will depend on their ability to provide a reflection of the underlying atherosclerotic burden or activity; the ability to provide reliable, accurate, and cost-effective information; and the ability to predict future events. High-sensitivity C-reactive protein (hs-CRP) fulfills many, if not all, of these criteria, and blood levels of hs-CRP are now commonly used in clinical practice to improve vascular risk prediction in primary and secondary prevention across all levels of low-density lipoprotein-cholesterol (LDL-C), all levels of the Framingham Risk Score, and all levels of metabolic syndrome. High-sensitivity C-reactive protein may also have clinical relevance as an adjunct to LDL-C for both the targeting and monitoring of statin therapy. Accumulating evidence suggests that several other selected emerging biomarkers may also potentially prove useful in the diagnosis and prognosis of cardiovascular disease. Specifically, data are accumulating on the potential clinical utility of lipoprotein-associated lipoprotein-associated phospholipase A2, myeloperoxidase, oxidized LDL, lipoprotein (a), isoprostanes, and small, dense LDL. This review focuses on hs-CRP and these emerging plasma biomarkers, and their potential diagnostic and prognostic utility in cardiovascular disease. Plasma biomarkers that reflect the clinical potential of atherothrombotic disease may allow more precise risk stratification and prognostication in high-risk populations, and perhaps earlier diagnosis and intervention in patients at risk for or with occult cardiovascular disease.

Reduction of oxidative stress and modulation of autoantibodies against modified low-density lipoprotein after rosuvastatin therapy

AIMS

To examine the effect of 24 weeks' rosuvastatin treatment on oxidative stress and changes in immune response to oxidized low-density lipoprotein (LDL).

METHODS

This was an open-label study of patients in Austria receiving 10 or 40 mg rosuvastatin daily alternately during 12 and 24 weeks. Circulating concentrations of antibodies to malondialdehyde-oxidized LDL (MDA-LDL), both IgG and IgM type, to copper-oxidized LDL (Cu-OxLDL-IgG), concentrations of oxidized LDL complexed to IgG (OxLDL-IC) and markers of oxidative stress and systemic inflammation in subjects with plasma LDL cholesterol concentrations between 130 mg dl-1 and 250 mg dl-1 and triglycerides

RESULTS

During statin therapy, plasma endogenous peroxides (POX-ACT) concentrations and peroxidase activity were significantly decreased, associated with a modest increase in total antioxidant capacity (TAC). Antibody titres to MDA-LDL-IgM, Cu-OxLDL-IgG and OxLDL-IC decreased, whereas MDA-LDL-IgG concentrations were increased after therapy. These changes were dose- and LDL-independent. POX-ACT concentrations were significantly positively correlated with inflammation markers before and after therapy and inversely with high-density lipoprotein-cholesterol concentrations after therapy.

CONCLUSION

This study provides in vivo evidence that rosuvastatin significantly reduces oxidative stress and has immunomodulatory properties in a dose- and LDL-independent manner.

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Key Words

• autoantibodies
• oxidative stress
• oxidatively modified low-density lipoprotein
• rosuvastatin

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MESH Headings

• Antioxidants/metabolism
• Autoantibodies/immunology
• Biomarkers/blood
• Copper/metabolism
• Dose-Response Relationship, Drug
• Female
• Fluorobenzenes/therapeutic use
• Humans
• Hydroxymethylglutaryl-CoA Reductase Inhibitors/therapeutic use
• Immunoglobulin G/immunology
• Immunoglobulin M/immunology
• Lipoproteins, LDL/metabolism
• Male
• Malondialdehyde/metabolism
• Middle Aged
• Oxidation-Reduction
• Oxidative Stress/drug effects
• Peroxidase/metabolism
• Peroxides/blood
• Pyrimidines/therapeutic use
• Rosuvastatin Calcium
• Sulfonamides/therapeutic use

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Grants Collapse

Affiliation(s)

Ulrike Resch Medical University of Vienna, Wilhelm Auerswald Atherosclerosis Research Group, Vienna, Austria.
Franz Tatzber
Alexandra Budinsky
Helmut Sinzinger

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Oxidized low-density lipoprotein biomarkers in atherosclerosis

The concept that the oxidation of lipoproteins is central in the pathogenesis of atherosclerosis was first reported over 25 years ago, initially by in vitro studies and subsequently through experimental models of atherosclerosis. The innate immune system plays a key role in atherogenesis as manifested by its atherosclerosis-modulating properties, the immunogenicity of oxidized low-density lipoprotein (LDL), and the presence of oxidized LDL autoantibodies in plasma and lesions of humans. In the past 10 years it has been possible to generate monoclonal antibodies to oxidized LDL to directly measure oxidized LDL in plasma. This has led to a rapidly accelerating pace of new reports on the relationship of circulating oxidized LDL and various cardiovascular pathologic processes, which are the focus of this review.

Lack of association between circulating levels of plasma oxidized low-density lipoproteins and clinical outcome after coronary stenting

BACKGROUND

We undertook this study to investigate whether there is an association between circulating oxidized low-density lipoproteins (OxLDLs) and outcome after coronary stenting.

METHODS

The study included 687 patients with coronary artery disease who underwent coronary stenting. Oxidized low-density lipoproteins were measured before coronary angiography. The median of OxLDL concentrations was 67.7 U/L. Patients were divided into 2 groups: the group with OxLDL levels < median (low OxLDL group, n = 345) and the group with OxLDL levels > or = median (high OxLDL group, n = 342). The combined incidence of major adverse cardiac events (death, myocardial infarction, and target vessel revascularization) was the primary end point. Angiographic restenosis was also evaluated.

RESULTS

The combined incidence of death, myocardial infarction, and target vessel revascularization was 27.2% (n = 94) in the low OxLDL group and 25.4% (n = 87) in the high OxLDL group (OR .92, 95% CI 0.68-1.23, P = .59). At 6-month angiography, restenosis was found in 28.1% of the patients (n = 74) in the low OxLDL group and in 24.2% of the patients (n = 61) in the high OxLDL group. (P = .31).

CONCLUSION

Our study shows no association between circulating levels of OxLDL and restenosis or other adverse events in patients with coronary artery disease after coronary stenting.

Clinical impact of vasomotor function assessment and the role of ACE-inhibitors and statins

Impaired endothelial function is recognised as one of the earliest events of atherogenesis. Endothelium-dependent vasomotion has been the principal method to assess endothelial function. In this article, we will discuss the clinical value of the different techniques to evaluate endothelium-dependent vasomotion. To date, there seems not to be a simple and reliably endothelial function test to identify asymptomatic subjects at increased risk for cardiovascular disease in clinical practice. Recent studies indicate that pharmacological interventions, in particular with ACE-inhibitors and statins, might improve endothelial function. However, there is no solid evidence that improvement of endothelial function is a necessity for the observed reduction in cardiovascular events by these compounds. Overall, at this moment, there is no place in clinical practice for the use of endothelial function as a method for risk assessment or target of pharmacological interventions.

Role of lipoprotein-associated phospholipase A2 in atherosclerosis: biology, epidemiology, and possible therapeutic target

The development of atherosclerotic vascular disease is invariably linked to the formation of bioactive lipid mediators and accompanying vascular inflammation. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an enzyme that is produced by inflammatory cells, co-travels with circulating low-density lipoprotein (LDL), and hydrolyzes oxidized phospholipids in LDL. Its biological role has been controversial with initial reports purporting atheroprotective effects of Lp-PLA2 thought to be a consequence of degrading platelet-activating factor and removing polar phospholipids in modified LDL. Recent studies, however, focused on pro-inflammatory role of Lp-PLA2 mediated by products of the Lp-PLA2 reaction (lysophosphatidylcholine and oxidized nonesterified fatty acids). These bioactive lipid mediators, which are generated in lesion-prone vasculature and to a lesser extent in the circulation (eg, in electronegative LDL), are known to elicit several inflammatory responses. The proinflammatory action of Lp-PLA2 is also supported by a number of epidemiology studies suggesting that the circulating level of the enzyme is an independent predictor of cardiovascular events, despite some attenuation of the effect by inclusion of LDL, the primary carrier of Lp-PLA2, in the analysis. These observations provide a rationale to explore whether inhibiting Lp-PLA2 activity and consequent interference with the formation of bioactive lipid mediators will abrogate inflammation associated with atherosclerosis, produce favorable changes in intermediate cardiovascular end points (eg, biomarkers, imaging, and endothelial function), and ultimately reduce cardiovascular events in high-risk patients.

Endothelial Dysfunction in Patients With Chronic Periodontitis and Its Improvement After Initial Periodontal Therapy

BACKGROUND

Recent epidemiological data suggested that there is a relationship between periodontal health and atherosclerotic coronary heart disease. Although hypothetical models were proposed, the exact mechanism of this association has not been clarified. The aim of this study is to investigate whether there is an endothelial dysfunction in patients with chronic periodontitis and, if present, whether recovery is possible with therapy.

METHODS

The study groups consisted of 28 patients (mean age: 45.5 +/- 8.6 years) with chronic periodontitis and without any atherosclerotic vascular disease, and 26 healthy controls (mean age: 43.7 +/- 6.8 years). Cardiovascular risk factors were investigated in both groups. Brachial artery responses to reactive hyperemia (endothelium-dependent dilatation [EDD]) and sublingual nitroglycerin (endothelium-independent dilatation [EID]) were measured using high-resolution vascular ultrasound in both groups. Measurements were taken before and after initial periodontal therapy in the periodontal patients.

RESULTS

There was no significant difference between the groups with regard to cardiovascular risk factors. In the baseline measurements, EDD and EID were significantly impaired in patients with chronic periodontitis when compared with the controls (8.4% +/- 4.0% versus 19.4% +/- 8.1%, P<0.0001; 13.3% +/- 6.3% versus 29.5% +/- 10.0%, P<0.0001 for EDD and EID, respectively). After non-surgical periodontal therapy, EDD and EID improved significantly (from 8.4% +/- 4.0% to 17.7% +/- 5.7%, P<0.0001; and from 13.3% +/- 6.3% to 24.9% +/- 7.3%, P<0.0001 for FMD and EID, respectively). The EDD and EID changes in the controls were insignificant.

CONCLUSION

This study showed that endothelial functions were impaired in patients with chronic periodontitis and that they improve following initial periodontal therapy.

Effects of statins on vascular structure and function: a systematic review

PURPOSE

Statins reduce cardiovascular events by more than can be explained by their effects on lipids. We conducted a systematic review of how statins affect vascular structure and function, differences among statins, and correlations between the effects of statins on vascular outcomes and either lipid levels or cardiovascular outcomes.

METHODS

We primarily searched MEDLINE (1980 to March 2004) to identify all studies with at least 10 subjects that reported the effects of currently available statins on coronary artery stenosis, carotid intima-media thickness, and endothelial function (excluding studies of drug combinations and subjects with organ transplants). Meta-analyses were performed when feasible.

RESULTS

Statins decrease the progression and increase the regression of coronary artery lesions and luminal narrowing. Compared with placebo, statins decrease the likelihood of coronary artery restenosis (summary risk ratio = 0.85; 95% confidence interval: 0.77 to 0.95). Statins appear to slow the progression of carotid artery intima-media thickness. Although the effect of statins on coronary endothelial function is uncertain, statins appear to improve peripheral endothelial function. There is no conclusive evidence to suggest that individual statins differ in their effects on these outcomes. Studies generally found weak or no correlation between the effects of statins on vascular outcomes and lipid levels. No study showed a correlation between vascular effect and clinical outcome.

CONCLUSION

Statins slow the progression of, and may reverse, atherosclerosis. The magnitude of these effects, however, is small compared with the effects of statins on cardiovascular events. Statins also improve measures of vascular function, which may contribute to their clinical benefits. There is insufficient evidence to suggest that individual statins differ in their vascular effects.

High-Dose Atorvastatin Reduces Total Plasma Levels of Oxidized Phospholipids and Immune Complexes Present on Apolipoprotein B-100 in Patients With Acute Coronary Syndromes in the MIRACL Trial

BACKGROUND

Oxidized phospholipids (OxPL) are present within atherosclerotic plaques and bound by lipoprotein (a) [Lp(a)] in plasma. This study evaluated the impact of atorvastatin on oxidized LDL (OxLDL) in patients with acute coronary syndromes (ACS).

METHODS AND RESULTS

OxLDL-E06 (OxPL content on apolipoprotein B-100 [apoB] detected by antibody E06), apoB-100 immune complexes (apoB-IC), OxLDL autoantibodies, and Lp(a) levels were measured in 2341 patients at baseline and after 16 weeks of treatment with atorvastatin 80 mg/d or placebo. The OxLDL-E06 and apoB-IC data are reported per apoB-100 particle (OxPL/apoB, IC/apoB) and as total levels on all apoB-100 particles (total apoB-OxPL and total apoB-IC [eg, OxPL/apoB or IC/apoBxapoB-100 levels]). Compared with baseline values, atorvastatin reduced apoB-100 (-33%), total apoB-OxPL (-29.7%), total apoB-IC IgG (-29.5%), and IgM (-25.7%) (P<0.0001 for all), whereas no change or an increase was observed with placebo. When normalized per apoB-100, compared with placebo, atorvastatin increased OxPL/apoB (9.5% versus -3.9%, P<0.0001) and Lp(a) (8.8% versus -0.7%, (P<0.0001). A strong correlation was noted between OxPL/apoB and Lp(a) (R=0.85, P<0.0001), consistent with previous data that Lp(a) binds OxPL.

CONCLUSIONS

After atorvastatin treatment, total OxPL on all apoB-100 particles was decreased. However, there was enrichment of OxPL on a smaller pool of apoB-100 particles, in parallel with similar increases in Lp(a), suggesting binding by Lp(a). These data support the hypothesis that atorvastatin promotes mobilization and clearance of proinflammatory OxPL, which may contribute to a reduction in ischemic events after ACS.

Plasma level of oxidized low-density lipoprotein is an independent determinant of coronary macrovasomotor and microvasomotor responses induced by bradykinin

OBJECTIVES

We examined the relationship between coronary endothelium-dependent vasodilation in response to bradykinin (BK) and plasma levels of oxidized low-density lipoprotein (oxLDL) in subjects with normal coronary arteries.

BACKGROUND

It is unclear whether the plasma oxLDL level is a determinant of coronary endothelial function. Bradykinin plays an important role in regulating resting coronary tone and flow-mediated coronary vasomotion.

METHODS

Coronary blood flow (CBF) in the left anterior descending (LAD) coronary artery was assessed by quantitative angiography and a Doppler flow wire in 94 consecutive subjects with normal coronary arteries. The plasma oxLDL level was measured by enzyme-linked immunosorbent assay using DLH3R, a specific antibody against oxLDL.

RESULTS

Plasma levels of oxLDL in diabetic subjects (n = 13) were higher than those in non-diabetic subjects (n = 81). Plasma levels of oxLDL correlated with body mass index (BMI). Bradykinin at doses of 0.2, 0.6, and 2.0 microg/min caused dose-dependent increases in diameter and CBF in the LAD coronary artery. By a univariate analysis, oxLDL levels significantly correlated with epicardial (r = -0.30, p < 0.0001) and resistant (r = -0.36, p = 0.003) coronary vasodilator responses to BK at 2.0 microg/min, whereas total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides were not associated with these coronary responses. In a stepwise multivariate analysis, oxLDL levels were significantly correlated with epicardial and resistant coronary vasomotor responses to BK, independent of age, gender, smoking status, other lipid levels, BMI, hypertension, and diabetes.

CONCLUSIONS

The plasma level of oxLDL is an appropriate surrogate for assessing coronary endothelial-dependent vasomotor function as estimated by responses to BK compared with conventional risk factors for atherosclerosis.