Improved Persistence to Medication, Decreased Cardiovascular Events and Reduced All-Cause Mortality in Hypertensive Patients With Use of Single-Pill Combinations: Results From the START-Study

BACKGROUND

Single-pill combination improves adherence and persistence to medication in hypertension. It remains unclear whether this also reduces cardiovascular outcomes and all-cause mortality. We analyzed whether single-pill combinations are superior to identical multiple pills on persistence to medication, cardiovascular outcomes, and all-cause mortality.

METHODS

This was a retrospective claims data (German AOK PLUS) analysis. Data from hypertensive patients ≥18 years treated with renin-angiotensin system combinations given as single pill or identical multipills covering the years 2012 to 2018 were analyzed and followed up to at least 1 year. After 1:1 propensity score matching, persistence to medication, cardiovascular events, and all-cause mortality were compared using non-parametric tests. Results were reported as incidence rate ratios and hazard ratios.

RESULTS

After propensity score matching data from 57 998 patients were analyzed: 10 801 patients received valsartan/amlodipine, 1026 candesartan/amlodipine, 15 349 ramipril/amlodipine, and 1823 amlodipine/valsartan/hydrochlorothiazide as single pill or identical multipill. No relevant differences in patient characteristics were observed within the 4 groups. In all groups, a significant lower all-cause mortality, a significant a higher persistence to medication, a significant lower event rate in 15 out of 20 comparisons, and a tendency in the remaining 5 comparisons was observed under single pills compared with multipill combinations.

CONCLUSIONS

Antihypertensive combination therapy reduces all-cause mortality and cardiovascular events when provided as single pill compared to identical drugs as multipills. This strongly supports the European Society of Cardiology/European Society of Hypertension and International Society of Hypertension guidelines recommending the use of a single-pill combination and thus should be more rigorously implemented into daily clinical practice.

Characterisation of multi-layered structures using a vector-based gradient descent algorithm at terahertz frequencies

Material characterisation and imaging applications using terahertz radiation have gained interest in the past few years due to their enormous potential for industrial applications. The availability of fast terahertz spectrometers or multi-pixel terahertz cameras has accelerated research in this domain. In this work, we present a novel vector-based implementation of the gradient descent algorithm to fit the measured transmission and reflection coefficients of multilayered objects to a scattering parameter-based model, without requiring any analytical formulation of the error function. We thereby extract thicknesses and refractive indices of the layers within a maximum 2% error margin. Using the precise thickness estimates, we further image a 50 nm-thick Siemens star deposited on a silicon substrate using wavelengths larger than 300 µm. The vector-based algorithm heuristically finds the error minimum where the optimisation problem cannot be analytically formulated, which can be utilised also for applications outside the terahertz domain.

Single pill treatment in daily practice is associated with improved clinical outcomes and all-cause mortality in cardiovascular diseases: results from the START project

Objective

Current guidelines for the management of arterial hypertension, dyslipidemia, or secondary cardiovascular (CV) prevention recommend combination drug treatments with single pill combinations (SPC). This concept is expected to improve adherence to treatment and, as a consequence, to reduce the risk of adverse CV outcomes associated with these clinical conditions. Aim of our study was to assess whether SPC are clinically superior to multi pill combination (MPC) with identical drugs in reducing CV events and al-cause mortality in a huge population under real world conditions in daily practice.

Methods

We analyzed an anonymized claims dataset (AOK PLUS, a statutory German sickness fund) including patients with hypertension and other CV diseases in the years 2012–2017; minimum follow-up was 1 year or until date of death, After 1:1-Propensity Score Matching (PSM), selected CV outcomes (myocardial infarction, stroke, transitory ischemic attack, coronary artery disease, heart failure, acute renal failure, cardiovascular hospitalization, all cause hospitalization) as well as all-cause mortality were compared using Incidence Rate Ratios (IRRs) and non-parametric tests.

Results

50,622 patients (25,311 patients in SPC versus MPC group) aged ≥18 years treated with SPC or identical MPC were followed up for at least 1 year or until death. No significant differences in baseline characteristics were observed after PSM. Nine different clinical outcomes were compared for each group. In all comparisons, significantly lower incidence rate ratios (IRR) were identified for SPC, confirmed by comparison of Kaplan-Meier estimates: stroke (IRR=0.77; 95% CI 0.67–0.88; p<0.001), transitory ischemic attack (IRR=0.61; 95% CI 0.48–0.78; p<0.001), myocardial infarction (IRR=0.76; 95% CI 0.63–0.90; p=0.0016), coronary artery disease (IRR=0.66; 95% CI 0.57–0.77; p<0.001), heart failure (IRR=0.59; 95% CI 0.54–0.64; p<0.001), acute renal failure (IRR=0.54; 95% CI 0.56–0.64; p<0.001) all cause hospitalization (IRR=0.72; 95% CI 0.71–0.74; p<0.001), cardiovascular hospitalization (IRR=0.63; 95% CI 0.57–0.69; p<0.001), and all-cause mortality (IRR=0.62; 95% CI 0.57–0.68; p<0.001). The mean time to first events and time to death were also in favor to SPC (any event: SPC 966.052 days/median 873; MPC 846.936 days/median 647; death: SPC 1,719.424 days; MPC 1,657.248 days; log rank for both comparisons: p<0.001).

Conclusion

In clinical practice, the SPC regimen is associated with a lower incidence of CV events and lower all-cause mortality. Time to the event is also significantly longer in the SPC group compared to MPC. These results strongly support the concept of SPC and the implementation into daily practice to improve patient's prognosis.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): APONTIS PHARMA GmbH & Co. KG

Effects of cardiovascular single pill combinations compared with identical multi-pill therapies on healthcare cost and utilization in Germany

Aim: This study assessed whether a single pill combination (SPC) is associated with lower direct healthcare costs. Materials & methods: Anonymized claims data of patients ≥18 years treated with drugs for cardiovascular (CV)-related diseases either as a single pill combination or multi-pill combination (follow-up to 1 year) were evaluated. After propensity score matching, 59,336 out of 1,369,840 patients were analyzed. Results: In all cohorts, patients receiving a single pill combination had a lower frequency of general practitioner and specialist visits. The patients also had a significantly lower ratio of all-cause hospitalization days and number of CV-related prescriptions as well as all-cause prescriptions (with one exception) compared with those receiving a multi-pill combination. Conclusion: Direct CV-related costs were significantly lower in four out of seven comparisons, with a trend toward lower costs in the other three comparisons.

Effects of Single Pill Combinations Compared to Identical Multi Pill Therapy on Outcomes in Hypertension, Dyslipidemia and Secondary Cardiovascular Prevention: The START-Study

Aim

Current guidelines for the treatment of arterial hypertension (AH) or cardiovascular (CV) prevention recommend combination drug treatments with single pill combinations (SPC) to improve adherence to treatment. We aimed to assess whether the SPC concept is clinically superior to multi pill combination (MPC) with identical drugs.

Methods and Results

In an explorative study, we analyzed anonymized claims data sets of patients treated with CV drugs for hypertension and/or CV disorders who were insured by the German AOK PLUS statutory health fund covering 01/07/2012-30/06/2018. Patients at age ≥18 years who received either a SPC or MPC with identical drugs were followed for up to one year. A one to one propensity score matching (PSM) was applied within patient groups who started identical drug combinations, and results were reported as incidence rate ratios (IRRs) as well as hazard ratios (HRs). After PSM, data from 59,336 patients were analyzed. In 30 out of 56 IRR analyses, superiority of SPC over MPC was shown. In 5 out of 7 comparisons, the HR for the composite outcome of all-cause death and all-cause hospitalizations was in favor of the SPC regimen (SPC versus MPC): valsartan/amlodipine: HR=0.87 (95% CI: 0.84–0.91, p ≤ 0.001); candesartan/amlodipine: 0.77 (95% CI: 0.65–0.90, p = 0.001); valsartan/amlodipine/hydrochlorothiazide: HR=0.68 (95% CI: 0.61–0.74, p ≤ 0.001); ramipril/amlodipine: HR=0.80 (95% CI: 0.77–0.83, p ≤ 0.001); acetylsalicylic acid (ASA)/atorvastatin/ramipril: HR=0.64 (95% CI: 0.47–0.88, p = 0.005).

Conclusion

SPC regimens are associated with a lower incidence of CV events and lower all-cause mortality in clinical practice. SPC regimens should generally be preferred to improve patient’s prognosis.

The age of randomized clinical trials: three important aspects of randomized clinical trials in cardiovascular pharmacotherapy with examples from lipid, diabetes, and antithrombotic trials

This review article aims to explain the important issues that data safety monitoring boards (DSMB) face when considering early termination of a trial and is specifically addressed to the needs of clinical and research cardiologists. We give an insight into the overall background and then focus on the three principal reasons for stopping trials, i.e. efficacy, futility, and harm. The statistical essentials are also addressed to familiarize clinicians with the key principles. The topic is further highlighted by numerous examples from lipid trials and antithrombotic trials. This is followed by an overview of regulatory aspects, including an insight into industry-investigator interactions. To conclude, we summarize the key elements that are the basis for a decision to stop a randomized clinical trial (RCT).

Challenges in Cardiovascular Pharmacogenomics Implementation: A viewpoint from the European Society of Cardiology Working Group on Cardiovascular Pharmacotherapy

Pharmacogenomics promises to advance cardiovascular therapy, but there remain pragmatic barriers to implementation. These are particularly important to explore within Europe, as there are differences in the populations, availability of resources and expertise, as well as in ethico-legal frameworks. Differences in healthcare delivery across Europe present a challenge, but also opportunities to collaborate on PGx implementation. Clinical work force upskilling is already in progress but will require substantial input. Digital infrastructure and clinical support tools are likely to prove crucial. It is important that widespread implementation serves to narrow rather than widen any existing gaps in health equality between populations. This viewpoint supplements the working group position paper on cardiovascular pharmacogenomics to address these important themes.

Inhibition of Rac1 GTPase Decreases Vascular Oxidative Stress, Improves Endothelial Function, and Attenuates Atherosclerosis Development in Mice

Aims: Oxidative stress and inflammation contribute to atherogenesis. Rac1 GTPase regulates pro-oxidant NADPH oxidase activity, reactive oxygen species (ROS) formation, actin cytoskeleton organization and monocyte adhesion. We investigated the vascular effects of pharmacological inhibition of Rac1 GTPase in mice.

Methods and Results: We treated wild-type and apolipoprotein E-deficient (ApoE^−/−) mice with Clostridium sordellii lethal toxin (LT), a Rac1 inhibitor, and assessed vascular oxidative stress, expression and activity of involved proteins, endothelial function, macrophage infiltration, and atherosclerosis development. LT-treated wild-type mice displayed decreased vascular NADPH oxidase activity and ROS production. Therapeutic LT doses had no impact on behavior, food intake, body weight, heart rate, blood pressure, vascular and myocardial function, differential blood count, and vascular permeability. ApoE^−/− mice were fed a cholesterol-rich diet and were treated with LT or vehicle. LT treatment led to decreased aortic Rac1 GTPase activity, NADPH oxidase activity and ROS production, but had no impact on expression and membrane translocation of NADPH oxidase subunits and RhoA GTPase activity. LT-treated mice showed improved aortic endothelium-dependent vasodilation, attenuated atherosclerotic lesion formation and reduced macrophage infiltration of atherosclerotic plaques. Concomitant treatment of cholesterol-fed ApoE^−/− mice with LT, the specific synthetic Rac1 inhibitor NSC 23766 or simvastatin comparably reduced aortic Rac1 activity, NADPH oxidase activity, oxidative stress, endothelial dysfunction, atherosclerosis development, and macrophage infiltration.

Conclusions: These findings identify an important role of the small GTPase Rac1 in atherogenesis and provide a potential target for anti-atherosclerotic therapy.

Update on management of hypokalemia and goals for the lower potassium level in patients with cardiovascular disease: A review in collaboration with the European Society of Cardiology Working Group on Cardiovascular Pharmacotherapy

Hypokalaemia is common in patients with cardiovascular disease. In this review, we emphasize the importance of tight potassium regulation in patients with cardiovascular disease based on findings from observational studies. To enhance the understanding, we also describe the mechanisms of potassium homeostasis maintenance, the most common causes of hypokalaemia and present strategies for monitoring and management of low potassium levels. We propose elevation of potassium in asymptomatic patients with lower normal concentrations and concurrent cardiovascular disease. These proposals are intended to assist clinicians until more evidence is available.

The Role of Pharmacogenomics in Contemporary Cardiovascular Therapy: A position statement from the European Society of Cardiology Working Group on Cardiovascular Pharmacotherapy

There is a strong and ever-growing body of evidence regarding the use of pharmacogenomics to inform cardiovascular pharmacology. However, there is no common position taken by international cardiovascular societies to unite diverse availability, interpretation and application of such data, nor is there recognition of the challenges of variation in clinical practice between countries within Europe. Aside from the considerable barriers to implementing pharmacogenomic testing and the complexities of clinically actioning results, there are differences in the availability of resources and expertise internationally within Europe. Diverse legal and ethical approaches to genomic testing and clinical therapeutic application also require serious thought. As direct-to-consumer genomic testing becomes more common, it can be anticipated that data may be brought in by patients themselves, which will require critical assessment by the clinical cardiovascular prescriber. In a modern, pluralistic and multi-ethnic Europe, self-identified race/ethnicity may not be concordant with genetically detected ancestry and thus may not accurately convey polymorphism prevalence. Given the broad relevance of pharmacogenomics to areas such as thrombosis and coagulation, interventional cardiology, heart failure, arrhythmias, clinical trials, and policy/regulatory activity within cardiovascular medicine, as well as to genomic and pharmacology subspecialists, this position statement attempts to address these issues at a wide-ranging level.

Persistence and cardiovascular outcomes with ramipril, atorvastatin, ASA as a single pill compared to the multi pill combination. A subanalysis of the START study, a claims data analysis

Background/Introduction

Large randomized clinical trials have shown the efficacy of aspirin (ASA), angiotensin converting enzyme inhibitors (ACEI) and statins (S) in secondary prevention. However, adherence to medication is low in patients suffering from a cardiovascular event and decreases with each additional tablet. Therefore, a single pill (SP) approach is considered to increase drug persistence and decrease cardiovascular events in this patient population.

Purpose

Data that show an advantage for a SP regimen containing ASA, ACEI, and S compared to the identical loose combination (LC) regarding persistence, and clinical outcomes under conditions of daily practise in one study are missing. We conducted the START study to answer these questions. A subset, in which we anlysed data from patients in secondary prevention is presented here.

Methods

The START study was a retrospective, non-interventional analysis of an anonymised claims dataset covering patients suffering from cardiovascular diseases insured by the German AOK PLUS public health insurance in the years 2012–2017. Patients at age ≥18 years with an indication for the use of a combination treatment in cardiovascular disorders – including the use of ASA, ramipril, and atorvastatin - in a SP or identical LC were followed up to 1 year. After 1:1-Propensity Score Matching (PSM) persistence (defined as redemption of prescription with a lack >60 days) and clinical outcomes were compared using non-parametric tests.

Results

Before PSM, 564,941 patients had a cardiovascular event in the medical history, 427,046 suffered from coronary artery disease. 275 received the three substances described above as SP, 6,662 as LC. After PSM, data from 211 patients were suitable for further analysis in each group. Baseline characteristics were comparable between SP and LC groups. Persistence to treatment was significant lower in the LC group (Hazard Ratio, HR, 0.25 [95% CI 0.19–0.34], p<0.001). 8 clinical outcomes were analysed. Lower Incidence Rate Ratio (IRR) was found in the SP group for myocardial infarction (IRR 0.46; 95% CI 0.07–2.36), stroke (IRR 0.51; 95% CI 0.04–4.46), transitory ischemic attac (IRR 0.77; 95% CI 0.01–60.12), coronary artery disease (IRR 0.60; 95% CI 0.25–1.43), and all cause mortality (IRR 0.38; 95% CI 0.06–1.79). All cause hospitalisation was significant lower in the SP group (IRR 0.58; 95% CI 0.47–0.72; p<0.001).

Conclusion

The number of patients receiving a SP regimen in secondary prevention was relatively low. However, persistence to medication was significantly higher in the SP group. In addition, a tendency for a lower IRR was also observed for cardiovascular events and all cause mortality in the SP group. The results of our analysis support the use of a SP regimen in secondary prevention of cardiovascular events.

Funding Acknowledgement

Type of funding source: None

Single pill regimen improves persistence and leads lo better clinical outcome compared to identical multi pill combination. Results of START, a German claims data analysis

Background/Introduction

The current ESC/ESH-Guidelines for the treatment of arterial hypertension (AH) recommend initiation and escalation of medical treatment using renin–angiotensin–aldosterone system (RAAS) blocker, diuretics (D) and/or calcium channel blockers (CCB). They also recommend a single pill (SP) regimen to improve persistence, to increase blood pressure control and to reduce cardiovascular events.

Purpose

Data showing an advantage for a SP regimen compared to the identical loose combination (LC) regarding all these parameters in a single study are missing. We report now the results comparing SP with identical LC regarding persistence and cardiovascular outcomes in daily practice.

Methods

This was a retrospective, non-interventional analysis of an anonymized claims dataset covering patients suffering from cardiovascular diseases insured by the German AOK PLUS public health insurance in the years 2012–2017. Patients at age ≥18 years with an indication for the use of a combination of RAAS-blockers, D and/or CCB as SP or identical LC were followed up for 1 year. After 1:1-Propensity Score Matching (PSM) persistence (defined as redemption of prescription with a lack >60 days) and clinical outcomes were compared using non-parametric tests.

Results

After PSM, baseline characteristics were comparable between SP and LC groups. Each group included 10,801 patients with valsartan/amlodipine, 1,026 with candesartan/amlodipine, 1,823 with amlodipine/valsartan/hydrochlorothiazide (HCT), and 15,349 with ramipril/amlodipine as SP or identical LC. 8 clinical outcomes were compared for each combination. Persistence to treatment was significant higher in the SP group. In 27 of 32 comparisons a significantly lower Incidence Rate Ratio (IRR) was identified for SP. This was confirmed by time-to-event-analysis. The largest patient group (ramipril/amlodipine) showed a significant lower risk for SP observed for stroke (IRR=0.746; 95% CI 0.627–0.886; p<0.001), transitory ischemic attack (IRR=0.693; 95% CI 0.496–0.963; p=0.023), myocardial infarction (IRR=0.623; 95% CI 0.493–0.784; p<0.001), coronary artery disease (IRR=0.579; 95% CI 0.462–0.723; p<0.001), heart failure (IRR=0.468; 95% CI 0.409–0.534; p<0.001), all cause hospitalization (IRR=0.670; 95% CI 0.652–0.687; p<0.001), cardiovascular hospitalization (IRR=0.596; 95% CI 0.519–0.685; p<0.001), and all cause mortality (IRR=0.526; 95% CI 0.463–0.596; p<0.001) compared to LC.

Conclusion

A SP regimen improves persistence to medication, reduces cardiovascular events and total mortality compared to identical LC. The results of the START study strongly support the use of a SP concept in the AH medication treatment as recommended by the current ESH/ESC-Guidelines for the treatment of AH.

Funding Acknowledgement

Type of funding source: None

Murine sca1/flk1-positive cells are not endothelial progenitor cells, but B2 lymphocytes

Circulating sca1⁺/flk1⁺ cells are hypothesized to be endothelial progenitor cells (EPCs) in mice that contribute to atheroprotection by replacing dysfunctional endothelial cells. Decreased numbers of circulating sca1⁺/flk1⁺ cells correlate with increased atherosclerotic lesions and impaired reendothelialization upon electric injury of the common carotid artery. However, legitimate doubts remain about the identity of the putative EPCs and their contribution to endothelial restoration. Hence, our study aimed to establish a phenotype for sca1⁺/flk1⁺ cells to gain a better understanding of their role in atherosclerotic disease. In wild-type mice, sca1⁺/flk1⁺ cells were mobilized into the peripheral circulation by granulocyte-colony stimulating factor (G-CSF) treatment and this movement correlated with improved endothelial regeneration upon carotid artery injury. Multicolor flow cytometry analysis revealed that sca1⁺/flk1⁺ cells predominantly co-expressed surface markers of conventional B cells (B2 cells). In RAG2-deficient mice and upon B2 cell depletion, sca1⁺/flk1⁺ cells were fully depleted. In the absence of monocytes, sca1⁺/flk1⁺ cell levels were unchanged. A PCR array focused on cell surface markers and next-generation sequencing (NGS) of purified sca1⁺/flk1⁺ cells confirmed their phenotype to be predominantly that of B cells. Finally, the depletion of B2 cells, including sca1⁺/flk1⁺ cells, in G-CSF-treated wild-type mice partly abolished the endothelial regenerating effect of G-CSF, indicating an atheroprotective role for sca1⁺/flk1⁺ B2 cells. In summary, we characterized sca1⁺/flk1⁺ cells as a subset of predominantly B2 cells, which are apparently involved in endothelial regeneration.

The age of randomized clinical trials: three important aspects of randomized clinical trials in cardiovascular pharmacotherapy with examples from lipid and diabetes trials

Randomized clinical trials (RCTs) are important and the Gold Standard for drugs in modern cardiovascular (CV) therapy. The cornerstone of RCTs is the recording of hard clinical endpoints instead of surrogates. It is important to select an appropriate endpoint. Efficacy endpoints must be clinically relevant and can be hierarchically divided. A very interesting innovation in endpoint acquisition is the total event paradigm.

Lipid management in rheumatoid arthritis: a position paper of the Working Group on Cardiovascular Pharmacotherapy of the European Society of Cardiology

Rheumatoid arthritis (RA) is associated with increased cardiovascular morbidity, partly due to alterations in lipoprotein quantity, quality and cell cholesterol trafficking. Although cardiovascular disease significantly contributes to mortality excess in RA, cardiovascular prevention has been largely insufficient. Because of limited evidence, optimal strategies for lipid management (LM) in RA have not been determined yet, and recommendations are largely based on expert opinions. In this position paper, we describe abnormalities in lipid metabolism and introduce a new algorithm for estimation of cardiovascular risk (CVR) and LM in RA. The algorithm stratifies patients according to RA-related factors impacting CVR (such as RA activity and severity and medication). We propose strategies for monitoring of lipid parameters and treatment of dyslipidaemia in RA (including lifestyle, statins and other lipid-modifying therapies, and disease modifying antirheumatic drugs). These opinion-based recommendations are meant to facilitate LM in RA until more evidence is available.

Antithrombotic therapy and major adverse limb events in patients with chronic lower extremity arterial disease: systematic review and meta-analysis from the European Society of Cardiology Working Group on Cardiovascular Pharmacotherapy in Collaboration with the European Society of Cardiology Working Group on Aorta and Peripheral Vascular Diseases

Aims

The role and selection of antithrombotic therapy to improve limb outcomes in chronic lower extremity artery disease (LEAD) is still debated. We conducted a meta-analysis to examine the efficacy and safety of antithrombotic and more intense antithrombotic therapy on limb outcomes and limb salvage in patients with chronic LEAD.

Methods and results

Study inclusion criteria were: enrolment of patients with LEAD, randomized allocation to more vs. less intense antithrombotic therapy [more vs. less intense single-antiplatelet therapy (SAPT); dual-antiplatelet therapy vs. SAPT; dual antithrombotic therapy vs. SAPT or oral anticoagulant]; enrolment of ≥200 patients; reporting of at least one of following outcomes: limb amputation or revascularization. Seven randomized studies enrolling 30 447 patients were included. Over a median follow-up of 24 months, more vs. less intense antithrombotic therapy or placebo significantly reduced the risk of limb revascularization [relative risk (RR) 0.89, 95% confidence interval (CI) 0.83–0.94] and limb amputation (RR 0.63, 95% CI 0.46–0.86), as well as stroke (RR 0.82, 95% CI 0.70–0.97). There was no statistically significant effect on the risk of myocardial infarction (RR 0.98, 95% CI 0.87–1.11), all-cause (RR 0.93, 95% CI 0.86–1.01), and cardiovascular death (RR 0.97, 95% CI 0.86–1.08). Risk of major bleeding increased (RR 1.23, 95% CI 1.04–1.44).

Conclusion

In patients with LEAD, more intense antithrombotic therapy reduces the risk of limb amputation and revascularization as well as stroke with an increase in the risk of bleeding events.

Bleeding and ischaemic outcomes in patients treated with dual or triple antithrombotic therapy: systematic review and meta-analysis

Aims

The combination of oral anticoagulation with a P2Y12 inhibitor and aspirin in patients with atrial fibrillation (AF) undergoing percutaneous coronary intervention (PCI) is associated with a high bleeding risk. Dual antithrombotic therapy (DAT) with omission of aspirin is a promising option to reduce bleedings, but carries a yet unknown risk of ischaemic events. We therefore sought to systematically review and analyse randomized controlled trials investigating DAT vs. triple antithrombotic therapy (TAT) in patients with AF following PCI and/or acute coronary syndrome (ACS).

Methods and results

We included four trials with overall 9317 patients (5039 DAT, 4278 TAT) in our analysis. Dual antithrombotic therapy was associated with a significant reduction in thrombolysis in myocardial infarction major bleeding [hazard ratio (HR) 0.52, 95% confidence interval (CI) 0.42–0.65; P = 0.0001], while the composite trial-defined ischaemic endpoint did not differ significantly between DAT and TAT (HR 0.98, 95% CI 0.79–1.22; P = 0.88). There was also no difference regarding the occurrence of myocardial infarction (MI; HR 1.16, 95% CI 0.92–1.46; P = 0.21) or stent thrombosis (HR 1.25, 95% CI 0.69–2.26; P = 0.46). Absolute numbers for MI were 131/4278 (3.1%) with TAT and 182/5039 (3.6%) with DAT, and for stent thrombosis 32/4278 (0.75%) and 52/5039 (1%), respectively. A post hoc power calculation based on the size and event rate of this meta-analysis revealed 80% power to detect a 37% and 100% increase in MI and stent thrombosis, respectively.

Conclusion

Dual antithrombotic therapy significantly reduces bleedings compared with TAT and seems to have a similar effect in preventing ischaemic endpoints in AF patients post-PCI or ACS. Future investigations are needed to determine its applicability specifically in patients at high risk of ischaemic outcomes.

Oral anticoagulation in patients with non-valvular atrial fibrillation and a CHA2DS2-VASc score of 1: a current opinion of the European Society of Cardiology Working Group on Cardiovascular Pharmacotherapy and European Society of Cardiology Council on Stroke

Oral anticoagulation in patients presenting with non-valvular atrial fibrillation and a CHA2DS2-VASc score of 1 (CHA2DS2-VASc of 2 in women) remains a challenging approach in clinical practice. Therapeutic decisions need to balance the individual benefit of reducing thromboembolic risk against the potential harm due to an increase in bleeding risk in this intermediate risk patient population. Within the current opinion statement of the European Society of Cardiology working group of cardiovascular pharmacotherapy and the European Society of Cardiology council on stroke the currently available evidence on the anti-thrombotic management in patients presenting with a CHA2DS2-VASc of 1 is summarized. Easily applicable tools for a personalized refinement of the individual thromboembolic risk in patients with atrial fibrillation and a CHA2DS2-VASc score of 1 that guide clinicians through the question whether to anticoagulate or not are provided.

Reasons for disparity in statin adherence rates between clinical trials and real-world observations: a review

With statins, the reported rate of adverse events differs widely between randomized clinical trials (RCTs) and observations in clinical practice, the rates being 1-2% in RCTs vs. 10-20% in the so-called real world. One possible explanation is the claim that RCTs mostly use a run-in period with a statin. This would exclude intolerant patients from remaining in the trial and therefore favour a bias towards lower rates of intolerance. We here review data from RCTs with more than 1000 participants with and without a run-in period, which were included in the Cholesterol Treatment Trialists Collaboration. Two major conclusions arise: (i) the majority of RCTs did not have a test dose of a statin in the run-in phase. (ii) A test dose in the run-in phase was not associated with a significantly improved adherence rate within that trial when compared to trials without a test dose. Taken together, the RCTs of statins reviewed here do not suggest a bias towards an artificially higher adherence rate because of a run-in period with a test dose of the statin. Other possible explanations for the apparent disparity between RCTs and real-world observations are also included in this review albeit mostly not supported by scientific data.

Absence of Four-and-a-Half LIM Domain Protein 2 Decreases Atherosclerosis in ApoE −/− Mice

Objective—

Four-and-a-half LIM domain protein-2 (FHL2) is expressed in endothelial cells, vascular smooth muscle cells, and leukocytes. It regulates cell survival, migration, and inflammatory response, but its role in atherogenesis is unknown.

Approach and Results—

To investigate the role of FHL2 in atherosclerosis, FHL2-deficient mice were crossed with ApoE-deficient mice, to generate ApoE/FHL2−/− mice. After high-fat diet, ApoE/FHL2−/− mice had significantly smaller atherosclerotic plaques than ApoE−/− mice in the aortic sinus, the brachiocephalic artery, and the aorta. This was associated with enhanced collagen and smooth muscle cell contents and a 2-fold reduction in macrophage content within the plaques of ApoE/FHL-2−/− versus ApoE−/− mice. This could be explained, in part, by the reduction in aortic ICAM-1 (intracellular adhesion molecule) mRNA and VCAM-1 (vascular cell adhesion molecule) protein expression in the plaque. Aortic gene expression of the chemokines CX3CL1 and CCL5 was increased in ApoE/FHL2−/− versus ApoE−/− mice. Peritoneal thioglycollate injection elicited equivalent numbers of monocytes and macrophages in both groups, but a significantly lower number of proinflammatory Ly6C high monocytes were recruited in ApoE/FHL2−/− versus ApoE−/− mice. Furthermore, mRNA levels of CX3CR1 were 2-fold higher in monocytes from ApoE/FHL2−/− versus ApoE−/− mice. Finally, we investigated the potential importance of myeloid cell FHL2 deficiency in atherosclerosis. After being irradiated, ApoE−/− or ApoE/FHL2−/− mice were transplanted with ApoE−/− or ApoE/FHL2−/− bone marrow. After high-fat diet, both chimeric groups developed smaller plaques than ApoE−/− transplanted with ApoE−/− bone marrow.

Conclusions—

These results suggest that FHL2 in both myeloid and vascular cells may play an important role in atherosclerosis by promoting proinflammatory chemokine production, adhesion molecule expression, and proinflammatory monocyte recruitment.

Abstract 643: Absence of Four-and-a-Half LIM Domain Protein 2 Decreases Atherosclerosis in ApoE-/- Mice: Role of Monocytic Immune Cells

Four-and-a-half LIM domain protein-2 (FHL2) is expressed in endothelial and vascular smooth muscle cells. It negatively regulates endothelial cell survival and migration, but its role in atherogenesis is unknown. To investigate the role of FHL2 in atherosclerosis, FHL2-deficient (FHL2-/-) mice were crossed with ApoE-deficient (ApoE -/-) mice, to generate ApoE/FHL2-/- mice. After 7 weeks of high fat diet, ApoE/FHL2-/- mice had significantly smaller (P<0.05) atherosclerotic plaques than ApoE-/- mice in the aortic sinus (0.14±0.02 vs. 0.29±0.04 mm2), the brachiocephalic artery (0.03±0.008 vs. 0.07±0.01 mm2) and the aorta (6.9±0.9 vs 10.3±1%), assessed by oil red O staining. This was associated with enhanced collagen (16±2 vs 8.6±3 %) and smooth muscle cell (4.5±0.8 vs 1.8±0.5%) contents within the plaques of ApoE/FHL-2-/- mice. Moreover, macrophage content within plaques was reduced 2-fold in ApoE/FHL2-/- vs ApoE-/- mice (P<0.05). This could be explained, in part, by the 40% reduction in aortic ICAM-1 mRNA and 55% reduction in VCAM-1 protein expression in the plaque. Furthermore, aortic gene expression of Cx3cl1 and Ccl5 was increased in ApoE/FHL2-/- vs ApoE-/- mice, suggesting that different monocyte populations might be recruited to the plaques. Peritoneal thioglycollate injection elicited equivalent numbers of monocytes and macrophages in both groups, but a significantly lower number of pro-inflammatory Ly6C high monocytes were recruited in ApoE/FHL2-/- vs ApoE-/- mice (8±3 vs 18±4%). Furthermore, mRNA levels of Cx3cr1 were 2-fold higher in monocytes from ApoE/FHL2-/- mice compared with ApoE-/- mice. Finally, we also investigated the potential importance of myeloid cell FHL2 deficiency in atherosclerosis. ApoE-/- or ApoE/FHL2-/- mice were lethally irradiated and transplanted with ApoE-/- or ApoE/FHL2-/- bone marrow. After recovery and 7 weeks of high fat diet, both chimeric groups developed smaller plaques than ApoE-/- mice transplanted with ApoE-/- bone marrow. These results suggest that FHL2 in both myeloid and vascular cells may play an important role in atherosclerosis by promoting pro-inflammatory chemokine production, adhesion molecule expression, and pro-inflammatory monocyte recruitment.

Distinct CD11b+-monocyte subsets accelerate endothelial cell recovery after acute and chronic endothelial cell damage

BACKGROUND

Endothelial cell recovery requires replenishment of primary cells from the endothelial lineage. However, recent evidence suggests that cells of the innate immune system enhance endothelial regeneration.

METHODS AND RESULTS

Focusing on mature CD11b+-monocytes, we analyzed the fate and the effect of transfused CD11b+-monocytes after endothelial injury in vivo. CD11b-diphtheria-toxin-receptor-mice--a mouse model in which administration of diphtheria toxin selectively eliminates endogenous monocytes and macrophages--were treated with WT-derived CD11b+-monocytes from age-matched mice. CD11b+-monocytes improved endothelium-dependent vasoreactivity after 7 days while transfusion of WT-derived CD11b--cells had no beneficial effect on endothelial function. In ApoE-/--CD11b-DTR-mice with a hypercholesterolemia-induced chronic endothelial injury transfusion of WT-derived CD11b+-monocytes stimulated by interferon-γ (IFNγ) decreased endothelial function, whereas interleukin-4-stimulated (IL4) monocytes had no detectable effect on vascular function. Bioluminescent imaging revealed restriction of transfused CD11b+-monocytes to the endothelial injury site in CD11b-DTR-mice depleted of endogenous monocytes. In vitro co-culture experiments revealed significantly enhanced regeneration properties of human endothelial outgrowth cells (EOCs) when cultured with preconditioned-media (PCM) or monocytes of IL4-stimulated-subsets compared to the effects of IFNγ-stimulated monocytes.

CONCLUSION

CD11b+-monocytes play an important role in endothelial cell recovery after endothelial injury by homing to the site of vascular injury, enhancing reendothelialization and improving endothelial function. In vitro experiments suggest that IL4-stimulated monocytes enhance EOC regeneration properties most likely by paracrine induction of proliferation and cellular promotion of differentiation. These results underline novel insights in the biology of endothelial regeneration and provide additional information for the treatment of vascular dysfunction.

Inhibition of four-and-a-half LIM domain protein-2 increases survival, migratory capacity, and paracrine function of human early outgrowth cells through activation of the sphingosine kinase-1 pathway: implications for endothelial regeneration

RATIONALE

Inhibition of four-and-a-half LIM domain protein-2 (FHL2) attenuates atherosclerotic lesion formation and increases endothelial cell migration. Early outgrowth cells (EOCs) contribute substantially to endothelial repair.

OBJECTIVE

We investigated the role of FHL2 in the regulation of EOCs.

METHODS AND RESULTS

Human EOCs were cultured from peripheral blood. FHL2 knockdown in EOCs by siRNA resulted in increased EOC numbers and reduced apoptosis, as indicated by decreased cleaved caspase-III and reduced Bax/Bcl-2 expression ratio. This was mediated through increased phosphorylation and membrane translocation of sphingosine kinase-1, increased sphingosine-1-phosphate levels, and Akt phosphorylation. FHL2 knockdown increased stromal cell-derived factor-1-induced EOC migration through upregulation of αv/β3, αv/β5, and β2 integrins, associated with increased cortactin expression. Reduced apoptosis, increased EOC migration, and cortactin upregulation by FHL2 siRNA were prevented by CAY10621, the sphingosine kinase-1 inhibitor, and the sphingosine-1-phosphate receptor-1/-3 antagonist VPC23019. These findings were confirmed using spleen-derived EOCs from FHL2(-/-) mice. Apoptosis was decreased and migration increased in endothelial cells exposed to the conditioned medium of FHL2(-/-) versus wild-type (WT) EOCs. These paracrine effects were abolished by VPC23019. Importantly, reendothelialization after focal carotid endothelial injury in WT mice was significantly increased after intravenous injection of FHL2(-/-) versus WT EOCs.

CONCLUSIONS

Our findings suggest that FHL2 negatively regulates EOC survival, migration, and paracrine function. FHL2 inhibition in EOCs reduces apoptosis and enhances survival and migratory capacity of both EOCs and surrounding endothelial cells by activation of the sphingosine kinase-1/sphingosine-1-phosphate pathway, resulting in improvement of endothelial regeneration.

Abstract 461: Inhibition of Four- and- a- Half LIM Domain Protein-2 Decreases Atherosclerosis in Apoe -/- Mice model: Role of Immune T- Cells

OBJECTIVE

Four-and-a-half LIM domain protein-2 (FHL2), a member of the FHL family of proteins, is expressed in endothelial and vascular smooth muscle cells. FHL2 negatively regulates endothelial cell survival and migration, but its role in atherogenesis is unknown.

METHODS AND RESULTS

To investigate the role of FHL2 in atherosclerosis, we crossed FHL2 knockout (FHL2-/-) with apolipoprotein (Apo) E-deficient (ApoE -/-) mice, and fed them a high fat diet for 7 weeks. Despite a total plasma cholesterol levels comparable to the ApoE-/- mice, FHL2-/-ApoE-/- mice showed a strong increase in plasma HDL-cholesterol as compared to ApoE -/- mice (P<0.01; n=6) and had significantly smaller atherosclerotic plaques in the aortic sinus (0.14±0.02 vs. 0.29±0.04 mm 2 ) and aorta (6.9±0.9 vs 10.3±1%) (P<0.05; n=6), assessed by oil red O staining, compared with ApoE-/- mice. The relative monocyte/ macrophage content within atherosclerotic plaques, determined by MOMA-2 immunostaining, was equivalent in both animal groups. However, we observed an enhanced relative content of collagen (16±2 vs 8.6±3 %) and smooth muscle cells (4.5±0.8 vs 1.8±0.5%) within the plaques in the aortic sinus of FHL2-/-ApoE-/- mice compared with ApoE-/- mice, determined by Sirius red and alpha-actin staining respectively. These results suggest that absence of FHL2 promotes smaller and more stable plaques. The reduced plaque size in FHL2-/-ApoE-/- mice could be explained, at least in part, by the 40% reduction in ICAM-1 mRNA expression observed in aortas (p<0.05 vs ApoE-/-). Moreover, although the relative monocyte/ macrophage content in spleens was equivalent in both animal groups, FACS analysis of T cells in spleens showed a significant increase in CD4+CD25+Foxp3+ regulatory T cell numbers, in FHL2-/-ApoE-/- compared with ApoE-/- mice (19.5±1.6 vs. 16.2±2% of CD3+CD4+ cells, respectively) (P<0.005).

CONCLUSIONS

These results suggest that FHL2 may play an important role in atherosclerosis by promoting plaque formation, through upregulation of adhesion molecule expression and suppression of regulatory T cells.

AT1-receptor-deficiency induced atheroprotection in diabetic mice is partially mediated via PPARγ

Objective

Peroxisome-proliferator–activated-receptor-γ (PPARγ) acts as a transcriptional regulator of multiple genes involved in glucose and lipid metabolism. In vitro studies showed that activated PPARγ suppresses AT1R-gene expression and vice versa. However, it has not yet been determined in vivo, whether AT1R-PPARγ-interactions play a relevant role in the pathogenesis of diabetic complications and specifically in accelerated atherosclerosis.

Methods and results

ApoE^−/− and ApoE^−/−/AT1R^−/−-mice were rendered diabetic by intraperitoneal injections of streptozotocin. Diabetic and non-diabetic ApoE^−/−-mice were further randomized to receive the AT1R antagonist telmisartan, the selective PPARγ antagonist GW9662, telmisartan and GW9662 or vehicle for 18 weeks. Diabetic and non-diabetic ApoE^−/−/AT1R^−/−-mice were randomized to receive either GW9662 or vehicle. GW9662 treatment in diabetic ApoE^−/− and diabetic ApoE^−/−/AT1^−/−-mice resulted in the highest elevation of fasting blood glucose levels, whereas telmisartan treatment and AT1 deficiency in ApoE^−/−-mice showed the lowest fasting blood glucose levels. Diabetic ApoE^−/−-mice displayed severe impairment of endothelial function, enhanced oxidative stress and increased atherosclerotic lesion formation. ApoE^−/−/AT1R^−/− and telmisartan-treated ApoE^−/−-mice showed a significantly better endothelial function, decreased oxidative stress and reduced atherosclerotic lesion formation. Treatment of diabetic ApoE^−/− and ApoE^−/−/AT1R^−/−-mice with the selective PPARγ antagonist GW9662 omitted the atheroprotective effects of AT1R deficiency or AT1 antagonism.

Conclusion

Genetic disruption or pharmacological inhibition of the AT1R attenuates atherosclerosis and improves endothelial function in diabetic ApoE^−/−-mice via the PPARγ pathway.

Abstract 200: Inhibition of Four-and-a-Half Lim Domain Protein 2 Increases Survival and Migratory Capacity of Human Early Outgrowth Endothelial Progenitor Cells Through Upregulation of Sphingosine Kinase-1: Implications for Endothelial Regeneration

Background: Inhibition of Four-and-a-half LIM domain protein-2 (FHL-2) attenuates atherosclerotic lesion formation and increases endothelial cell migration. Endothelial progenitor cells (EPCs) substantially contribute to endothelial repair. We investigated the role of FHL-2 in the regulation of early outgrowth EPC number and function.

Methods and Results: Early outgrowth EPCs were obtained from human peripheral blood. FHL-2 knockdown in EPCs by small-interfering RNA (siRNA) resulted in a significant increase in EPC number and a reduction of apoptosis (by 40%), as indicated by a decrease of cleaved caspase-3, through activation and translocation to the membrane, of sphingosine kinase-1 (SK-1), enzyme that metabolizes sphingosine- 1 phosphate (s1p). Furthermore, FHL-2 siRNA increased significantly (2 fold) stromal derived factor (SDF) -1- induced EPC migration; through upregulation of α-v/β-3 and α-v/β-5 integrins; this was associated with an increase of the F-actin binding protein cortactin, known to promote migration. Interestingly, increased SDF-1- induced EPC migration and upregulation of cortactin by FHL-2 siRNA were totally prevented by CAY10621 , a specific inhibitor of SK-1. In addition stimulation of EPCs with exogenous s1p peptide significantly decreased apoptosis and increased SDF-1- induced migration. These results were confirmed In vivo using FHL-2 knockout (FHL-2 -/-) mice. Moreover, apoptosis was significantly decreased and migration increased in endothelial cells exposed to the conditioned medium of FHL-2 -/- vs. WT EPCs. These effects were abolished by VPC23019 , an antagonist of sphingosine- 1- phosphate receptor- 1 and 3. Finally, reendothelialization after focal carotid endothelial electric injury in WT mice was significantly increased after application of spleen-derived progenitor cells from FHL-2 -/- mice vs. WT mice.

Conclusions: Our findings suggest that FHL-2 negatively regulates early outgrowth EPC function and secretion of paracrine factors. FHL-2 inhibition reduces apoptosis, enhances survival and migratory capacity of EPCs and ECs by upregulating SK-1/s1p pathway, integrin subunits and cortactin; which results in the improvement of endothelial regeneration.

Stimulation of the AT2 receptor reduced atherogenesis in ApoE(-/-)/AT1A(-/-) double knock out mice

AT1 receptor blockers (ARB) and in part ACE inhibitors (ACI) potentially exert beneficial effects on atherogenesis independent of AT1 receptor inhibition. These pleiotropic effects might be related to angiotensin II mediated activation of the AT2 receptor. To analyze this hypothesis we investigated the development of atherosclerosis and the role of ACIs and ARBs in apolipoprotein E-deficient (ApoE(-/-)) mice and in ApoE/AT1A receptor double knockout mice (ApoE(-/-)/AT1A(-/-)). ApoE(-/-) mice and ApoE(-/-)/AT1A(-/-) mice were fed cholesterol-rich diet for 7 weeks. Vascular oxidative stress, endothelial dysfunction, and atherosclerotic lesion formation were evident in ApoE(-/-) mice, but were markedly reduced in ApoE(-/-)/AT1A(-/-) mice. Concomitant treatment of ApoE(-/-)/AT1A(-/-) mice with either telmisartan or ramipril had no additional effect on blood pressure, vascular oxidative stress, AT2 receptor expression, and endothelial function. Remarkably, atherosclerotic lesion formation was increased in ramipril treated ApoE(-/-)/AT1A(-/-) mice compared to untreated ApoE(-/-)/AT1A(-/-) mice whereas pharmacological AT1 receptor inhibition with telmisartan had no additional effect on atherogenesis. Moreover, chronic AT2 receptor inhibition with PD123,319 significantly increased plaque development in ApoE(-/-)/AT1A(-/-) mice. In additional experiments, direct AT2 receptor stimulation reduced atherogenesis in ApoE(-/-)/AT1A(-/-) mice. Taken together, our data demonstrate a relevant antiatherosclerotic role of the AT2 receptor in atherosclerotic mice and provide novel insight in RAS-physiology.

Angiotensin II impairs endothelial progenitor cell number and function in vitro and in vivo: implications for vascular regeneration

Endothelial progenitor cells (EPCs) contribute to endothelial regeneration. Angiotensin II (Ang II) through Ang II type 1 receptor (AT(1)-R) activation plays an important role in vascular damage. The effect of Ang II on EPCs and the involved molecular mechanisms are incompletely understood. Stimulation with Ang II decreased the number of cultured human early outgrowth EPCs, which express both AT(1)-R and Ang II type 2 receptor, mediated through AT(1)-R activation and induction of oxidative stress. Ang II redox-dependently induced EPC apoptosis through increased apoptosis signal-regulating kinase 1, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase phosphorylation; decreased Bcl-2 and increased Bax expression; and activation of caspase 3 but had no effect on the low cell proliferation. In addition, Ang II impaired colony-forming and migratory capacities of early outgrowth EPCs. Ang II infusion diminished numbers and functional capacities of EPCs in wild-type (WT) but not AT(1)a-R knockout mice (AT(1)a(-/-)). Reendothelialization after focal carotid endothelial injury was decreased during Ang II infusion. Salvage of reendothelialization by intravenous application of spleen-derived progenitor cells into Ang II-treated WT mice was pronounced with AT(1)a(-/-) cells compared with WT cells, and transfusion of Ang II-pretreated WT cells into WT mice without Ang II infusion was associated with less reendothelialization. Transplantation of AT(1)a(-/-) bone marrow reduced atherosclerosis development in cholesterol-fed apolipoprotein E-deficient mice compared with transplantation of apolipoprotein E-deficient or WT bone marrow. Randomized treatment of patients with stable coronary artery disease with the AT(1)-R blocker telmisartan significantly increased the number of circulating CD34/KDR-positive EPCs. Ang II through AT(1)-R activation, oxidative stress, and redox-sensitive apoptosis signal-regulating kinase 1-dependent proapoptotic pathways impairs EPCs in vitro and in vivo, resulting in diminished vascular regeneration.

Activation of endothelial toll-like receptor 3 impairs endothelial function

RATIONALE

Endothelial dysfunction and atherosclerosis are chronic inflammatory diseases characterized by activation of the innate and acquired immune system. Specialized protein receptors of the innate immune system recognize products of microorganisms and endogenous ligands such as nucleic acids. Toll-like receptor 3 (TLR3), for example, detects long double-stranded RNA and is abundantly expressed in endothelial cells. Whether innate immunity contributes to atherogenic mechanisms in endothelial cells is poorly understood.

OBJECTIVE

We sought to determine the effects of TLR3 activation in endothelial cells.

METHODS AND RESULTS

We first investigated whether stimulation of TLR3 influences endothelial biology in mice. Intravenous injection of polyinosine polycytidylic acid, a synthetic double-stranded RNA analog and TLR3 ligand, impaired endothelium-dependent vasodilation, increased vascular production of reactive oxygen species, and reduced reendothelialization after carotid artery injury in wild-type mice compared with controls but had no effect in TLR3(-/-) animals. TLR3 stimulation not only induced endothelial dysfunction but also enhanced the formation of atherosclerotic plaques in apolipoprotein E-deficient mice. In vitro incubation of endothelial cells with polyinosine polycytidylic acid induced production of the proinflammatory cytokines interleukin-8 and interferon-γ-induced protein 10, increased formation of reactive oxygen species, diminished proliferation, and increased apoptosis, which suggests that endothelial cells are able to directly detect and respond to TLR3 ligands. Neutralization of interleukin-8 and interferon-γ-induced protein 10 antagonizes the observed negative effects of polyinosine polycytidylic acid. We found elevated levels of circulating endothelial progenitor cells in polyinosine polycytidylic acid-treated mice, although they displayed increased endothelial dysfunction. Stimulation of TLR3 in cultured endothelial progenitor cells, however, led to increased formation of reactive oxygen species, increased apoptosis, and reduced migration. Injection of endothelial progenitor cells that had been incubated with polyinosine polycytidylic acid ex vivo hindered reendothelialization after carotid artery injury. Therefore, endothelial progenitor cell function was affected by TLR3 stimulation. Finally, apolipoprotein E-deficient/TLR3-deficient mice exhibited improved endothelial function compared with apolipoprotein E-deficient/TLR3(+/+) littermates.

CONCLUSIONS

Immunorecognition of long double-stranded RNA by endothelial cells may be an important mechanism involved in endothelial cell activation and development of endothelial dysfunction.

Antiproliferative effect of estrogen in vascular smooth muscle cells is mediated by Kruppel-like factor-4 and manganese superoxide dismutase

The mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD) and the zinc finger transcription factor Kruppel-like factor-4 (KLF4) are involved in the regulation of redox homeostasis, apoptosis and cell proliferation. We have shown that estrogen exerts antioxidative actions via induction of MnSOD in cultured rat aortic vascular smooth muscle cells (VSMC). The purpose of the present study was to investigate whether estrogen inhibits VSMC proliferation via alteration of KLF4 and MnSOD expression. In cultured rat aortic VSMC, estrogen binding to estrogen receptor-alpha led to rapid increase in KLF4 expression and reduction of cell proliferation by 50%. Protein separation revealed that KLF4 was shifted to the nucleus when VSMC were treated with estrogen. Estrogen-mediated induction of KLF4 and the antiproliferative effect involved activation of PI-3 kinase, Akt phosphorylation and induction of NO synthase activity. Experiments in freshly isolated denuded aortic segments revealed an increase in KLF4 abundance after estrogen treatment and demonstrated that eNOS is expressed in the media at low levels. Transfection experiments showed that estrogen-induced overexpression of MnSOD required KLF4 and that both KLF4 and MnSOD were indispensable for the observed antiproliferative effect of estrogen in VSMC. To confirm these data in vivo, we investigated neointima formation after carotid artery injury in wild-type (WT) and MnSOD+/- mice. Estrogen deficiency led to enhanced neointima formation and higher numbers of Ki67-positive proliferating cells in the neointima of ovariectomized WT and MnSOD+/- mice. Moreover, MnSOD+/- mice showed more extensive neointima formation and Ki67 immunostaining. Interestingly, estrogen replacement prevented neointima formation in WT mice but failed to completely inhibit neointima formation in MnSOD+/- mice. Cultured VSMC derived from MnSOD+/- mice showed enhanced proliferation as compared to WT VSMC, and estrogen treatment failed to inhibit proliferation in MnSOD+/- VSMC. In conclusion, these data demonstrate the importance of MnSOD and KLF4 for proliferation control in VSMC. Our results provide novel insights into how proliferation of VSMC is regulated by estrogen and may help to identify novel targets for the treatment of vascular diseases such as restenosis.

Mitogen-activated protein kinase-activated protein kinase 2 in angiotensin II-induced inflammation and hypertension: regulation of oxidative stress

Vascular oxidative stress and inflammation play an important role in angiotensin II-induced hypertension, and mitogen-activated protein kinases participate in these processes. We questioned whether mitogen-activated protein kinase-activated protein kinase 2 (MK2), a downstream target of p38 mitogen-activated protein kinase, is involved in angiotensin II-induced vascular responses. In vivo experiments were performed in wild-type and Mk2 knockout mice infused intravenously with angiotensin II. Angiotensin II induced a 30 mm Hg increase in mean blood pressure in wild-type that was delayed in Mk2 knockout mice. Angiotensin II increased superoxide production and vascular cell adhesion molecule-1 in blood vessels of wild-type but not in Mk2 knockout mice. Mk2 knockdown by small interfering RNA in mouse mesenteric vascular smooth muscle cells caused a 42% reduction in MK2 protein and blunted the angiotensin II-induced 40% increase of MK2 expression. Mk2 knockdown blunted angiotensin II-induced doubling of intracellular adhesion molecule-1 expression, 2.4-fold increase of nuclear p65, and 1.4-fold increase in Ets-1. Mk2 knockdown abrogated the angiotensin II-induced 4.7-fold and 1.3-fold increase of monocyte chemoattractant protein-1 mRNA and protein. Angiotensin II enhanced reactive oxygen species levels (by 29%) and nicotinamide adenine dinucleotide phosphate oxidase activity (by 48%), both abolished by Mk2 knockdown. Reduction of MK2 blocked angiotensin II-induced p47phox translocation to the membrane, associated with a 53% enhanced catalase expression. Angiotensin II-induced increase of MK2 was prevented by the nicotinamide adenine dinucleotide phosphate oxidase inhibitor Nox2ds-tat. Mk2 small interfering RNA prevented the angiotensin II-induced 30% increase of proliferation. In conclusion, MK2 plays a critical role in angiotensin II signaling, leading to hypertension, oxidative stress via activation of p47phox and inhibition of antioxidants, and vascular inflammation and proliferation.

Role of the multidrug resistance protein-1 (MRP1) for endothelial progenitor cell function and survival

The multidrug resistance related protein-1 (MRP1) is a member of the ATP binding cassette (ABC) of cell surface transport proteins expressed in multiple cell lines and tissues including endothelial cells and haematopoietic stem cells. MRP1 blockade has been shown to prevent endothelial cell apoptosis and improve endothelial function. Besides mature endothelial cells vascular homing of endothelial progenitor cells (EPC) contributes to endothelial regeneration after vascular damage. Thus, we hypothesized that MRP1 influences number and function of EPCs and mechanisms of vascular repair. To test this, we investigated the effects of MRP1 inhibition in vitro and in vivo. MRP1 is abundantly expressed in cultured human early outgrowth EPCs. Pharmacological inhibition of MRP1 by MK571 increased intracellular glutathione levels and reduced intracellular reactive oxygen species levels. This stabilization of the intracellular redox homeostasis via inhibition of MRP1 prevented angiotensin II-induced apoptosis and increased the number of early outgrowth EPCs and colony forming units in vitro. To extend the observed cytoprotective effect of MRP1 blockade in EPCs to an in vivo situation, MRP1(-/-) knockout mice were investigated. MRP1(-/-) knockout mice showed significantly increased numbers of EPCs circulating in the peripheral blood and residing in the bone marrow. Consistently, colony forming unit formation was enhanced and rate of apoptosis reduced in early outgrowth EPCs derived from MRP1(-/-) knockout mice. In addition, MRP1(-/-) knockout mice showed improved reendothelialization after carotid artery injury, and transfusion of MNCs derived from MRP1(-/-) knockout mice into wild-type mice accelerated reendothelialization compared to transfusion of wild-type cells. These findings indicate that the enhanced function and survival of EPCs in MRP1(-/-) knockout mice resulted in improved reendothelialization. In conclusion, MRP1 negatively influences EPC function and survival via perturbation of the intracellular redox homeostasis which finally leads to increased cellular apoptosis. These results reveal novel mechanistic insights and may identify MRP1 as therapeutic target to improve reendothelialization after vascular damage.

Synergistic effects of telmisartan and simvastatin on endothelial progenitor cells

Circulating endothelial progenitor cells (EPC) contribute to endothelial replenishment. Telmisartan is an angiotensin-receptor blocker with PPARγ-agonistic properties. PPARγ-agonists and HMG-CoA reductase inhibitors have been shown to enhance EPC number and function. We focused on the effects of telmisartan alone or in combination with simvastatin on EPC. EPC were isolated from healthy human volunteers, cultured and stimulated with telmisartan, simvastatin, or the combination of telmisartan and simvastatin. Telmisartan significantly increased the number of acLDL/lectin double-positive early EPC, the number of colony forming units (EC-CFU) as well as EPC migratory capacity, inhibited TNFα-induced EPC apoptosis and reduced glucose-induced oxidative stress. The telmisartan effect was dose-dependent and could be inhibited by GW9662, indicating a PPARγ-dependent mechanism. The combination of telmisartan and simvastatin led to a significant additive increase in EPC count and function. In wild-type mice, systemic treatment with either telmisartan or simvastatin elevated the number of sca-1/flk-1-positive EPC in bone marrow and peripheral blood, spleen-derived acLDL/lectin double-positive EPC, EPC migration and EC-CFU. Consistent with the in vitro findings, the combination of telmisartan and simvastatin resulted in a further enhancement of EPC counts. Re-endothelialization after carotid injury was significantly enhanced by telmisartan, simvastatin and the combination. Telmisartan increases EPC number and function mediated by a PPARγ-dependent mechanism. This effect is further enhanced by combination with simvastatin, suggesting a synergistic activation of potentially diverse intracellular pathways.