Frailty and sarcopenia within the earliest national Dutch childhood cancer survivor cohort (DCCSS-LATER): a cross-sectional study

BACKGROUND

Childhood cancer survivors appear to be at increased risk of frailty and sarcopenia, but evidence on the occurrence of and high-risk groups for these aging phenotypes is scarce, especially in European survivors. The aim of this cross-sectional study was to assess the prevalence of and explore risk factors for pre-frailty, frailty, and sarcopenia in a national cohort of Dutch childhood cancer survivors diagnosed between 1963 and 2001.

METHODS

Eligible individuals (alive at the time of study, living in the Netherlands, age 18-45 years, and had not previously declined to participate in a late-effects study) from the Dutch Childhood Cancer Survivor Study (DCCSS-LATER) cohort were invited to take part in this cross-sectional study. We defined pre-frailty and frailty according to modified Fried criteria, and sarcopenia according to the European Working Group on Sarcopenia in Older People 2 definition. Associations between these conditions and demographic and treatment-related as well as endocrine and lifestyle-related factors were estimated with two separate multivariable logistic regression models in survivors with any frailty measurement or complete sarcopenia measurements.

FINDINGS

3996 adult survivors of the DCCSS-LATER cohort were invited to participate in this cross-sectional study. 1993 non-participants were excluded due to lack of response or a decline to participate and 2003 (50·1%) childhood cancer survivors aged 18-45 years were included. 1114 (55·6%) participants had complete frailty measurements and 1472 (73·5%) participants had complete sarcopenia measurements. Mean age at participation was 33·1 years (SD  7·2). 1037 (51·8%) participants were male, 966 (48·2%) were female, and none were transgender. In survivors with complete frailty measurements or complete sarcopenia measurements, the percentage of pre-frailty was 20·3% (95% CI 18·0-22·7), frailty was 7·4% (6·0-9·0), and sarcopenia was 4·4% (3·5-5·6). In the models for pre-frailty, underweight (odds ratio [OR] 3·38 [95% CI 1·92-5·95]) and obesity (OR 1·67 [1·14-2·43]), cranial irradiation (OR 2·07 [1·47-2·93]), total body irradiation (OR 3·17 [1·77-5·70]), cisplatin dose of at least 600 mg/m² (OR 3·75 [1·82-7·74]), growth hormone deficiency (OR 2·25 [1·23-4·09]), hyperthyroidism (OR 3·72 [1·63-8·47]), bone mineral density (Z score ≤-1 and >-2, OR 1·80 [95% CI 1·31-2·47]; Z score ≤-2, OR 3·37 [2·20-5·15]), and folic acid deficiency (OR 1·87 [1·31-2·68]) were considered significant. For frailty, associated factors included age at diagnosis between 10-18 years (OR 1·94 [95% CI 1·19-3·16]), underweight (OR 3·09 [1·42-6·69]), cranial irradiation (OR 2·65 [1·59-4·34]), total body irradiation (OR 3·28 [1·48-7·28]), cisplatin dose of at least 600 mg/m² (OR 3·93 [1·45-10·67]), higher carboplatin doses (per g/m²; OR 1·15 [1·02-1·31]), cyclophosphamide equivalent dose of at least 20 g/m² (OR 3·90 [1·65-9·24]), hyperthyroidism (OR 2·87 [1·06-7·76]), bone mineral density Z score ≤-2 (OR 2·85 [1·54-5·29]), and folic acid deficiency (OR 2·04 [1·20-3·46]). Male sex (OR 4·56 [95%CI 2·26-9·17]), lower BMI (continuous, OR 0·52 [0·45-0·60]), cranial irradiation (OR 3·87 [1·80-8·31]), total body irradiation (OR 4·52 [1·67-12·20]), hypogonadism (OR 3·96 [1·40-11·18]), growth hormone deficiency (OR 4·66 [1·44-15·15]), and vitamin B12 deficiency (OR 6·26 [2·17-1·81]) were significantly associated with sarcopenia.

INTERPRETATION

Our findings show that frailty and sarcopenia occur already at a mean age of 33 years in childhood cancer survivors. Early recognition and interventions for endocrine disorders and dietary deficiencies could be important in minimising the risk of pre-frailty, frailty, and sarcopenia in this population.

FUNDING

Children Cancer-free Foundation, KiKaRoW, Dutch Cancer Society, ODAS Foundation.

Longitudinal profile of circulating endothelial cells in post-acute coronary syndrome patients

IntroductionPatients who have experienced an acute coronary syndrome (ACS) are at risk of a recurrent event, but their level of risk varies. Because of their close temporal relationship with vascular injury, longitudinal measurements of circulating endothelial cells (CECs) carry potential to improve individual risk assessment.MethodsWe conducted an explorative nested case-control study within our multicenter, prospective, observational biomarker study (BIOMArCS) of 844 ACS patients. Following an index ACS, high-frequency blood sampling was performed during 1-year follow-up. CECs were identified using flow cytometric analyses in 15 cases with recurrent event, and 30 matched controls.ResultsCases and controls had a median (25^th-75^thpercentile) age of 64.1 (58.1-75.1) years and 80% were men. During the months preceding the endpoint, the mean (95%CI) CEC concentration in cases was persistently higher than in controls (12.8 [8.2-20.0] versus 10.0 [7.0-14.4] cells/ml), although this difference was non-significant (P = 0.339). In controls, the mean cell concentration was significantly (P = 0.030) lower in post 30-day samples compared to samples collected within one day after index ACS: 10.1 (7.5-13.6) versus 17.0 (10.8-26.6) cells/ml. Similar results were observed for CEC subsets co-expressing CD133 and CD309 (VEGFR-2) or CD106 (VCAM-1).ConclusionDespite their close relation to vascular damage, no increase in cell concentrations were found prior to the occurrence of a secondary adverse cardiac event.

Risk and determinants of low and very low bone mineral density and fractures in a national cohort of Dutch adult childhood cancer survivors (DCCSS-LATER): a cross-sectional study

BACKGROUND

Childhood cancer survivors are at risk of developing skeletal comorbidities later in life. We aimed to assess risk factors for low and very low bone mineral density (BMD), and the risk of and risk factors for any fractures and vertebral fractures in a national cohort of Dutch adult childhood cancer survivors.

METHODS

In this cross-sectional study, we used data from the DCCSS LATER cohort, which comprised individuals who were alive for at least 5 years after diagnosis of childhood cancer (ie, histologically confirmed malignancies or Langerhans cell histiocytosis), were diagnosed before the age of 19 years, and who had been treated at one of seven Dutch paediatric oncology centres between 1963 and 2002 (hereafter referred to as survivors). For this study, we invited survivors aged 18-45 years, who were alive as of Oct 10, 2016, living in the Netherlands, and who were deemed eligible by their treating physician to participate. We assessed BMD using dual-energy x-ray absorptiometry (DXA). Self-reported fractures that occurred at least 5 years after cancer diagnosis were assessed using available medical history and compared with population-level data from the Swedish national registry. We assessed vertebral fractures in a subset of participants using a vertebral fracture assessment. We assessed associations between the occurrence of low (Z-score of ≤-1) or very low (Z-score of ≤-2) BMD, fractures, and vertebral fractures and demographic, treatment-related, endocrine, and lifestyle-related factors using logistic regression analysis.

FINDINGS

Between April 29, 2016, and Jan 22, 2020, 3996 (64·8%) of 6165 individuals from the DCCSS LATER cohort were invited to participate, of whom 2003 (50·1%) were enrolled (mean age at participation was 33·1 years [SD 7·2], 966 [48·2%] were female, and 1037 [51·8%] were male [data on ethnicity and race were not available due to national policies]). 1548 (77·3%) had evaluable DXA scans for assessment of BMD, 1892 (94·5%) provided medical history of fractures, and 249 (12·4%) were assessed for vertebral fractures. 559 (36·1%) of 1548 had low BMD at any site, and 149 (9·6%) had very low BMD at any site. The standardised incidence ratio of any first fracture was 3·53 (95% CI 3·06-4·06) for male participants and 5·35 (4·46-6·52) for female participants. 33 (13·3%) of 249 participants had vertebral fractures. Male sex, underweight, high carboplatin dose, any dose of cranial radiotherapy, hypogonadism, hyperthyroidism, low physical activity, and severe vitamin D deficiency were associated with low BMD at any site and male sex, underweight, cranial radiotherapy, growth hormone deficiency, and severe vitamin D deficiency were associated with very low BMD at any site. Additionally, male sex, former and current smoking, and very low lumbar spine BMD were associated with any fractures, whereas older age at follow-up, previous treatment with platinum compounds, growth hormone deficiency, and low physical activity were specifically associated with vertebral fractures.

INTERPRETATION

Survivors of childhood cancer are at increased risk of any first fracture. Very low lumbar spine BMD was associated with fractures, highlighting the importance of active BMD surveillance in high-risk survivors (ie, those treated with cranial, craniospinal, or total body irradiation). Moreover, our results indicate that intensive surveillance and timely interventions for endocrine disorders and vitamin deficiencies might improve bone health in childhood cancer survivors, but this needs to be assessed in future studies.

FUNDING

Children Cancer-free Foundation (KiKa), KiKaRoW, and ODAS foundation.

From novel discovery tools and biomarkers to precision medicine-basic cardiovascular science highlights of 2021/22

Here, we review the highlights of cardiovascular basic science published in 2021 and early 2022 on behalf of the European Society of Cardiology Council for Basic Cardiovascular Science. We begin with non-coding RNAs which have emerged as central regulators cardiovascular biology, and then discuss how technological developments in single-cell 'omics are providing new insights into cardiovascular development, inflammation, and disease. We also review recent discoveries on the biology of extracellular vesicles in driving either protective or pathogenic responses. The Nobel Prize in Physiology or Medicine 2021 recognized the importance of the molecular basis of mechanosensing and here we review breakthroughs in cardiovascular sensing of mechanical force. We also summarize discoveries in the field of atherosclerosis including the role of clonal haematopoiesis of indeterminate potential, and new mechanisms of crosstalk between hyperglycaemia, lipid mediators, and inflammation. The past 12 months also witnessed major advances in the field of cardiac arrhythmia including new mechanisms of fibrillation. We also focus on inducible pluripotent stem cell technology which has demonstrated disease causality for several genetic polymorphisms in long-QT syndrome and aortic valve disease, paving the way for personalized medicine approaches. Finally, the cardiovascular community has continued to better understand COVID-19 with significant advancement in our knowledge of cardiovascular tropism, molecular markers, the mechanism of vaccine-induced thrombotic complications and new anti-viral therapies that protect the cardiovascular system.

Ambiguous definitions for baseline serum creatinine affect acute kidney diagnosis at the emergency department

Background

Acute kidney injury (AKI) incidence is increasing, however AKI is often missed at the emergency department (ED). AKI diagnosis depends on changes in kidney function by comparing a serum creatinine (SCr) measurement to a baseline value. However, it remains unclear to what extent different baseline values may affect AKI diagnosis at ED.

Methods

Routine care data from ED visits between 2012 and 2019 were extracted from the Utrecht Patient Oriented Database. We evaluated baseline definitions with criteria from the RIFLE, AKIN and KDIGO guidelines. We evaluated four baseline SCr definitions (lowest, most recent, mean, median), as well as five different time windows (up to 365 days prior to ED visit) to select a baseline and compared this to the first measured SCr at ED. As an outcome, we assessed AKI prevalence at ED.

Results

We included 47,373 ED visits with both SCr-ED and SCr-BL available. Of these, 46,100 visits had a SCr-BL from the − 365/− 7 days time window. Apart from the lowest value, AKI prevalence remained similar for the other definitions when varying the time window. The lowest value with the − 365/− 7 time window resulted in the highest prevalence (21.4%). Importantly, applying the guidelines with all criteria resulted in major differences in prevalence ranging from 5.9 to 24.0%.

Conclusions

AKI prevalence varies with the use of different baseline definitions in ED patients. Clinicians, as well as researchers and developers of automatic diagnostic tools should take these considerations into account when aiming to diagnose AKI in clinical and research settings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02581-x.

Microarray testing in patients with systemic lupus erythematosus identifies a high prevalence of CpG DNA-binding antibodies

Objective

Many autoantibodies are known to be associated with SLE, although their role in clinical practice is limited because of low sensitivity and weak associations with clinical manifestations. There has been great interest in the discovery of new autoantibodies to use in clinical practice. In this study, we investigated 57 new and known antibodies and their potential for diagnostics or risk stratification.

Methods

Between 2014 and 2017, residual sera of all anti-dsDNA tests in the UMC Utrecht were stored in a biobank. This included sera of patients with SLE, patients with a diagnosis of another immune-mediated inflammatory disease (IMID), patients with low (non-IMID) or medium levels of clinical suspicion of SLE but no IMID diagnosis (Rest), and self-reported healthy blood bank donors. Diagnosis and (presence of) symptoms at each blood draw were retrospectively assessed in the patient records with the Utrecht Patient-Oriented Database using a newly developed text mining algorithm. Sera of patients were analysed for the presence of 57 autoantibodies with a custom-made immunofluorescent microarray. Signal intensity cut-offs for all antigens on the microarray were set to the 95th percentile of the non-IMID control group. Differences in prevalence of autoantibodies between patients with SLE and control groups were assessed.

Results

Autoantibody profiles of 483 patients with SLE were compared with autoantibody profiles of 1397 patients from 4 different control groups. Anti-dsDNA was the most distinguishing feature between patients with SLE and other patients, followed by antibodies against Cytosine-phosphate-Guanine (anti-CpG) DNA motifs (p<0.0001). Antibodies against CMV (cytomegalovirus) and ASCA (anti-Saccharomyces cerevisiae antibodies) were more prevalent in patients with SLE with (a history of) lupus nephritis than patients with SLE without nephritis.

Conclusion

Antibodies against CpG DNA motifs are prevalent in patients with SLE. Anti-CMV antibodies are associated with lupus nephritis.

Severe lymphopenia acquired during chemoradiotherapy for esophageal cancer: Incidence and external validation of a prediction model

BACKGROUND

The incidence of grade 4 lymphopenia in patients treated with chemoradiotherapy (CRT) according to Chemoradiotherapy for Oesophageal cancer followed by Surgery Study (CROSS) regimen is unclear. The primary aim was to determine the incidence of grade 4 lymphopenia during CROSS for esophageal cancer. Secondary aims were to externally validate a prediction model for grade 4 lymphopenia and compare overall survival between patients with and without grade 4 lymphopenia.

METHODS

Patients who underwent CRT for esophageal cancer between 2014 and 2019 were eligible for inclusion. Patients with a planned radiation dose of 41.4 Gy (CROSS) or 50.4 Gy ("extended-CROSS") and concurrent carboplatin and paclitaxel were included. The primary outcome was the incidence of grade 4 lymphopenia during CRT defined according to Common Terminology Criteria for Adverse Events version 5.0 (i.e. lymphocyte count nadir < 0.2 µL). The secondary outcome measures were the prediction model's external performance (i.e. discrimination and calibration). Overall survival for patients with versus without grade 4 lymphopenia was compared using Kaplan-Meier analysis.

RESULTS

A total of 219 patients were included of whom 176 patients (80%) underwent CROSS and 43 patients (20%) extended-CROSS. The incidence of grade 4 lymphopenia was 11% in CROSS and 33% in extended-CROSS (p < 0.001). External discrimination yielded a c-statistic of 0.80 (95% confidence interval: 0.70-0.89). External calibration of the model was poor in CROSS but fair in extended-CROSS. Adjusted calibration using intercept correction (adjusted for the lower a-priori risk for grade 4 lymphopenia in CROSS) showed fair agreement between the observed and predicted risk for grade 4 lymphopenia. Median overall survival in patients with versus without grade 4 lymphopenia was 12.7 versus 42.5 months (p = 0.045).

CONCLUSION

The incidence of grade 4 lymphopenia is significantly higher in esophageal cancer patients receiving extended-CROSS compared to those receiving CROSS. The prediction model demonstrated good external performance in the setting of the CROSS-regimen and could be used to identify patients at high-risk for grade 4 lymphopenia who might be eligible for lymphopenia-mitigating strategies.

Endothelial function in cardiovascular medicine: a consensus paper of the European Society of Cardiology Working Groups on Atherosclerosis and Vascular Biology, Aorta and Peripheral Vascular Diseases, Coronary Pathophysiology and Microcirculation, and Thrombosis

Endothelial cells (ECs) are sentinels of cardiovascular health. Their function is reduced by the presence of cardiovascular risk factors, and is regained once pathological stimuli are removed. In this European Society for Cardiology Position Paper, we describe endothelial dysfunction as a spectrum of phenotypic states and advocate further studies to determine the role of EC subtypes in cardiovascular disease. We conclude that there is no single ideal method for measurement of endothelial function. Techniques to measure coronary epicardial and micro-vascular function are well established but they are invasive, time-consuming, and expensive. Flow-mediated dilatation (FMD) of the brachial arteries provides a non-invasive alternative but is technically challenging and requires extensive training and standardization. We, therefore, propose that a consensus methodology for FMD is universally adopted to minimize technical variation between studies, and that reference FMD values are established for different populations of healthy individuals and patient groups. Newer techniques to measure endothelial function that are relatively easy to perform, such as finger plethysmography and the retinal flicker test, have the potential for increased clinical use provided a consensus is achieved on the measurement protocol used. We recommend further clinical studies to establish reference values for these techniques and to assess their ability to improve cardiovascular risk stratification. We advocate future studies to determine whether integration of endothelial function measurements with patient-specific epigenetic data and other biomarkers can enhance the stratification of patients for differential diagnosis, disease progression, and responses to therapy.

Cardiovascular imaging of women and men visiting the outpatient clinic with chest pain or discomfort: design and rationale of the ARGUS Study

INTRODUCTION

Chest pain or discomfort affects 20%-40% of the general population over the course of their life and may be a symptom of myocardial ischaemia. For the diagnosis of obstructive macrovascular coronary artery disease (CAD), algorithms have been developed; however, these do not exclude microvascular angina. This may lead to false reassurance of symptomatic patients, mainly women, with functionally significant, yet non-obstructive coronary vascular disease. Therefore, this study aims to estimate the prevalence of both macrovascular and microvascular coronary vascular disease in women and men presenting with chest pain or discomfort, and to subsequently develop a decision-support tool to aid cardiologists in referral to cardiovascular imaging for both macrovascular and microvascular CAD evaluation.

METHODS AND ANALYSIS

Women and men with chest pain or discomfort, aged 45 years and older, without a history of cardiovascular disease, who are referred to an outpatient cardiology clinic by their general practitioner are eligible for inclusion. Coronary CT angiography is used for anatomical imaging. Additionally, myocardial perfusion imaging by adenosine stress cardiac MRI is performed to detect functionally significant coronary vascular disease. Electronic health record data, collected during regular cardiac work-up, including medical history, cardiovascular risk factors, physical examination, echocardiography, (exercise) ECG and blood samples for standard cardiovascular biomarkers and research purposes, are obtained. Participants will be classified as positive or negative for coronary vascular disease based on all available data by expert panel consensus (a cardiovascular radiologist and two cardiologists). After completion of the clinical study, all collected data will be used to develop a decision support tool using predictive modelling and machine-learning techniques.

ETHICS AND DISSEMINATION

The study protocol was approved by the Institutional Review Board of the University Medical Center Utrecht. Results will be disseminated through national and international conferences and in peer-reviewed journals in cardiovascular disease.

TRIAL REGISTRATION NUMBER

Trialregister.nl Registry NL8702.

Immunometabolism and atherosclerosis: perspectives and clinical significance: a position paper from the Working Group on Atherosclerosis and Vascular Biology of the European Society of Cardiology

Inflammation is an important driver of atherosclerosis, and the favourable outcomes of the Canakinumab Anti-inflammatory Thrombosis Outcome Study (CANTOS) trial revealed the large potential of anti-inflammatory drugs for the treatment of cardiovascular disease, especially in patients with a pro-inflammatory constitution. However, the complex immune reactions driving inflammation in the vascular wall in response to an atherosclerotic microenvironment are still being unravelled. Novel insights into the cellular processes driving immunity and inflammation revealed that alterations in intracellular metabolic pathways are strong drivers of survival, growth, and function of immune cells. Therefore, this position paper presents a brief overview of the recent developments in the immunometabolism field, focusing on its role in atherosclerosis. We will also highlight the potential impact of immunometabolic markers and targets in clinical cardiovascular medicine.

Association of low testosterone with changes in non-cardiovascular biomarkers in adult men

Testosterone has effects on many organs and systems. The purpose of this study was to test the hypothesis that low testosterone is associated with changes in various non-cardiovascular biomarkers in men older than 40 who were tested for possible hypogonadism. We extracted data from 9939 outpatient men who were over 40 years old (median age 56) and who also had concurrent laboratory measurements of total testosterone and one or more biomarkers of interest: estradiol, uric acid, prostate-specific antigen (PSA), sex-hormone binding globulin (SHBG), luteinizing hormone, creatinine, bone alkaline phosphatase (BAP), creatine kinase, hemoglobin A1c, and 25-hydroxy-vitamin D, and body mass index (BMI). In a smaller exploratory study of 19 otherwise healthy men presenting for evaluation of possible hypogonadism, pre-albumin (a.k.a.transthyretin, a marker of anabolism) and testosterone were measured. Men with lower levels of testosterone had significantly (p < 0.001) lower mean levels of PSA, SHBG, luteinizing hormone, and estradiol. Overall, men with low levels of testosterone also had significantly (p < 0.001) higher mean levels of LDH and BAP, but these associations varied between men who were younger or older than 56 years. There was a moderate but statistically significant positive correlation (r = 0.63, p < 0.05) between testosterone levels and pre-albumin. These results confirm our hypothesis that testosterone deficiency is associated with a broad range of systemic changes demonstrable in hormonal and non-hormonal serum assays in men over 40 years old being tested for possible hypogonadism.

Zytokinbeschichtete Stents als neue Werkzeuge der angiogenen Therapie

Die Stimulation des endogenen adaptiven Gefäßwachstums (Angiogenese, Arteriogenese) stellt einen vielversprechenden alternativen Therapieansatz zur Behandlung okklusiver Gefäßerkrankungen dar. Trotz der Vielzahl experimentell wirksamer Substanzen ist der erfolgreiche Transfer in den klinischen Gebrauch jedoch ausgeblieben. Als Hauptgrund für die beobachteten neutralen Effekte wird unter anderem die Art der Applikation angesehen. Obwohl präklinische Studien die Überlegenheit einer kontinuierlichen intraarteriellen Gabe gezeigt haben, wurde mangels technischer Machbarkeit in klinischen Studien auf Bolustherapie bzw. intravenöse oder subkutane Applikation ausgewichen. Die Fortschritte in der Entwicklung der ˶drug eluting stents“ eröffnen neue Möglichkeiten der lokalen Medikamentenfreisetzung, insbesondere im Koronarstromgebiet. Die Abgabe von Wachstumsfaktoren wie TGF-beta von solchen Stents ließ sich experimentell bereits zur Stimulation des Kollateralwachstums nutzen. Ein solcher Ansatz wird in Zukunft weitere Möglichkeiten der ortbegrenzten Therapie schaffen und z. B. die gezielte Stabilisierung atherosklerotischer Plaques ermöglichen.

MicroRNA-100 Suppresses Chronic Vascular Inflammation by Stimulation of Endothelial Autophagy

RATIONALE

The interaction of circulating cells within the vascular wall is a critical event in chronic inflammatory processes, such as atherosclerosis, but the control of the vascular inflammatory state is still largely unclear.

OBJECTIVE

This study was undertaken to characterize the function of the endothelial-enriched microRNA miR-100 during vascular inflammation and atherogenesis.

METHODS AND RESULTS

Based on a transcriptome analysis of endothelial cells after miR-100 overexpression, we identified miR-100 as a potent suppressor of endothelial adhesion molecule expression, resulting in attenuated leukocyte-endothelial interaction in vitro and in vivo as shown by flow cytometry and intravital imaging. Mechanistically, miR-100 directly repressed several components of mammalian target of rapamycin complex 1-signaling, including mammalian target of rapamycin and raptor, which resulted in a stimulation of endothelial autophagy and attenuated nuclear factor κB signaling in vitro and in vivo. In a low-density lipoprotein receptor-deficient atherosclerotic mouse model, pharmacological inhibition of miR-100 resulted in enhanced plaque lesion formation and a higher macrophage content of the plaque, whereas a systemic miR-100 replacement therapy had protective effects and attenuated atherogenesis, resulting in a decrease of plaque area by 45%. Finally, analysis of miR-100 expression in >70 samples obtained during carotid endarterectomy revealed that local miR-100 expression was inversely correlated with inflammatory cell content in patients.

CONCLUSIONS

In summary, we describe an anti-inflammatory function of miR-100 in the vascular response to injury and inflammation and identify an important novel modulator of mammalian target of rapamycin signaling and autophagy in the vascular system. Our findings of miR-100 as a potential protective anti-athero-miR suggest that the therapeutic replacement of this microRNA could be a potential strategy for the treatment of chronic inflammatory diseases, such as atherosclerosis, in the future.

Stabilisation of atherosclerotic plaques

Plaque rupture and subsequent thrombotic occlusion of the coronary artery account for as many as three quarters of myocardial infarctions. The concept of plaque stabilisation emerged about 20 years ago to explain the discrepancy between the reduction of cardiovascular events in patients receiving lipid lowering therapy and the small decrease seen in angiographic evaluation of atherosclerosis. Since then, the concept of a vulnerable plaque has received a lot of attention in basic and clinical research leading to a better understanding of the pathophysiology of the vulnerable plaque and acute coronary syndromes. From pathological and clinical observations, plaques that have recently ruptured have thin fibrous caps, large lipid cores, exhibit outward remodelling and invasion by vasa vasorum. Ruptured plaques are also focally inflamed and this may be a common denominator of the other pathological features. Plaques with similar characteristics, but which have not yet ruptured, are believed to be vulnerable to rupture. Experimental studies strongly support the validity of anti-inflammatory approaches to promote plaque stability. Unfortunately, reliable non-invasive methods for imaging and detection of such plaques are not yet readily available. There is a strong biological basis and supportive clinical evidence that low-density lipoprotein lowering with statins is useful for the stabilisation of vulnerable plaques. There is also some clinical evidence for the usefulness of antiplatelet agents, beta blockers and renin-angiotensin-aldosterone system inhibitors for plaque stabilisation. Determining the causes of plaque rupture and designing diagnostics and interventions to prevent them are urgent priorities for current basic and clinical research in cardiovascular area.

Biobanks and the search for predictive biomarkers of local and systemic outcome in atherosclerotic disease

Multiple risk factors have been associated with progression of atherosclerosis. To identify the individual patient who is at risk for disruption of a vulnerable plaque, leading to a cardiovascular event, remains a major challenge. Current screening methods, based on traditional risk factors, do not allow risk stratification on an individual level. The discovery of new biomarkers would aid in identifying specific patient groups at risk for adverse cardiovascular events due to atherosclerotic disease progression. The current definition of the vulnerable plaque, e.g. atheromatous inflammatory plaque with a thin fibrous cap, has been based on cross-sectional post-mortem studies. The predictive value of these histological characteristics of the vulnerable plaque is likely to be low, because they are also frequently observed at multiple locations in symptomatic and asymptomatic patients. The Athero-express study follows a new concept to search for the atherosclerotic patient who may suffer from adverse events. In this study, we investigate the predictive value of local plaque composition for adverse events in other vascular territories, regarding the plaque as a concentrated expression of this systemic disease. First results from this longitudinal biobank study show that the local plaque hides strong predictive value for cardiovascular events elsewhere in the vascular tree. Longitudinal biobank studies will facilitate the identification of novel local plaque markers. The search for the plaque protein signature that is predictive for adverse events might enable patient stratification that will allow individualized tailor made medicine and subsequently guide the choice for therapeutic interventions.

Impaired kidney function is associated with intraplaque hemorrhage in patients undergoing carotid endarterectomy

BACKGROUND AND AIMS

Previously, we showed that patients undergoing carotid endarterectomy have an increased risk for major atherosclerotic events in the presence of moderate or poor kidney function. Acceleration of vascular inflammatory responses is considered to be causally involved in progression of atherogenesis and poor outcome in chronic kidney disease patients. The association between kidney function and plaque composition has not been thoroughly investigated yet. The aim of this study was to investigate the association between kidney function and atherosclerotic plaque composition in patients undergoing carotid endarterectomy.

METHODS

Atherosclerotic plaques, harvested from 1796 patients who underwent carotid endarterectomy, were immunohistochemically stained for macrophages, smooth muscle cells, calcifications, collagen, microvessels, lipid core size and intraplaque hemorrhage. Cytokines were measured in plaque and plasma and associated with kidney function. Quantitative proteomics were performed on 40 carotid plaques and associated with kidney function.

RESULTS

Decreased kidney function was associated with increased odds ratio of intraplaque hemorrhage, OR 1.15 (95% CI; 1.02-1.29 (p = 0.024)) and increased odds ratio of fibrous-atheromatous plaques (plaques with lipid core presenting more than 10% of total plaque surface) OR 1.21 (95% CI; 1.07-1.38 (p = 0.003)) per decrease of 20 points in eGFR. Proteomics revealed that decreased kidney function was associated with upregulation of the classical pathway of the complement system and the intrinsic pathway of the coagulation system.

CONCLUSIONS

Decreased kidney function was associated with plaque hemorrhage but not with inflammatory plaque characteristics. Our data suggests that other pathways than the inflammation-pathway are involved in plaque vulnerability and poor outcome in patients with decreased kidney function.

MicroRNA-132/212 family enhances arteriogenesis after hindlimb ischaemia through modulation of the Ras-MAPK pathway

Arteriogenesis is a complicated process induced by increased local shear-and radial wall-stress, leading to an increase in arterial diameter. This process is enhanced by growth factors secreted by both inflammatory and endothelial cells in response to physical stress. Although therapeutic promotion of arteriogenesis is of great interest for ischaemic diseases, little is known about the modulation of the signalling cascades via microRNAs. We observed that miR-132/212 expression was significantly upregulated after occlusion of the femoral artery. miR-132/212 knockout (KO) mice display a slower perfusion recovery after hind-limb ischaemia compared to wildtype (WT) mice. Immunohistochemical analysis demonstrates a clear trend towards smaller collateral arteries in KO mice. Although Ex vivo aortic ring assays score similar number of branches in miR-132/212 KO mice compared to WT, it can be stimulated with exogenous miR-132, a dominant member of the miR-132/212 family. Moreover, in in vitro pericyte-endothelial co-culture cell assays, overexpression of miR-132 and mir-212 in endothelial cells results in enhanced vascularization, as shown by an increase in tubular structures and junctions. Our results suggested that miR-132/212 may exert their effects by enhancing the Ras-Mitogen-activated protein kinases MAPK signalling pathway through direct inhibition of Rasa1, and Spred1. The miR-132/212 cluster promotes arteriogenesis by modulating Ras-MAPK signalling via direct targeting of its inhibitors Rasa1 and Spred1.

MicroRNA-155 Exerts Cell-Specific Antiangiogenic but Proarteriogenic Effects During Adaptive Neovascularization

BACKGROUND

Adaptive neovascularization after arterial occlusion is an important compensatory mechanism in cardiovascular disease and includes both the remodeling of pre-existing vessels to collateral arteries (arteriogenesis) and angiogenic capillary growth. We now aimed to identify regulatory microRNAs involved in the modulation of neovascularization after femoral artery occlusion in mice.

METHODS AND RESULTS

Using microRNA-transcriptome analysis, we identified miR-155 as a downregulated microRNA during hindlimb ischemia. Correspondingly, inhibition of miR-155 in endothelial cells had a stimulatory effect on proliferation and angiogenic tube formation via derepression of its direct target gene angiotensin II type 1 receptor. Surprisingly, miR-155-deficient mice showed an unexpected phenotype in vivo, with a strong reduction of blood flow recovery after femoral artery ligation (arteriogenesis) dependent on the attenuation of leukocyte-endothelial interaction and a reduction of proarteriogenic cytokine expression. Consistently, miR-155-deficient macrophages exhibit a specific alteration of the proarteriogenic cytokine expression profile, which is partly mediated by the direct miR-155 target gene SOCS-1.

CONCLUSIONS

Our data demonstrate that miR-155 exerts an antiangiogenic but proarteriogenic function in the regulation of neovascularization via the suppression of divergent cell-specific target genes and that its expression in both endothelial and bone marrow-derived cells is essential for arteriogenesis in response to hindlimb ischemia in mice.

Increased platelet reactivity is associated with circulating platelet-monocyte complexes and macrophages in human atherosclerotic plaques

OBJECTIVE

Platelet reactivity, platelet binding to monocytes and monocyte infiltration play a detrimental role in atherosclerotic plaque progression. We investigated whether platelet reactivity was associated with levels of circulating platelet-monocyte complexes (PMCs) and macrophages in human atherosclerotic carotid plaques.

METHODS

Platelet reactivity was determined by measuring platelet P-selectin expression after platelet stimulation with increasing concentrations of adenosine diphosphate (ADP), in two independent cohorts: the Circulating Cells cohort (n = 244) and the Athero-Express cohort (n = 91). Levels of PMCs were assessed by flow cytometry in blood samples of patients who were scheduled for percutaneous coronary intervention (Circulating Cells cohort). Monocyte infiltration was semi-quantitatively determined by histological examination of atherosclerotic carotid plaques collected during carotid endarterectomy (Athero-Express cohort).

RESULTS

We found increased platelet reactivity in patients with high PMCs as compared to patients with low PMCs (median (interquartile range): 4153 (1585-11267) area under the curve (AUC) vs. 9633 (3580-21565) AUC, P<0.001). Also, we observed increased platelet reactivity in patients with high macrophage levels in atherosclerotic plaques as compared to patients with low macrophage levels in atherosclerotic plaques (mean ± SD; 8969 ± 3485 AUC vs. 7020 ± 3442 AUC, P = 0.02). All associations remained significant after adjustment for age, sex and use of drugs against platelet activation.

CONCLUSION

Platelet reactivity towards ADP is associated with levels of PMCs and macrophages in human atherosclerotic carotid plaques.

Taking risk prediction to the next level. Advances in biomarker research for atherosclerosis

Advances in risk prediction are necessary to stem the tide of the increasing incidence of global cardiovascular disease. Newly discovered biomarkers are needed for primary and secondary prevention and will undoubtedly play a major role in drug development programs and monitoring of treatment efficacy. The combination of improved -omics technologies and the investigation of relatively untapped sources of biomarkers will likely result in risk algorithms that will add value on top of the traditional risk factors. New sources of biomarkers are being explored with encouraging results. These include microvesicles, microRNAs, circulating cells and atherosclerotic plaques. We will review these sources for their potential for new biomarkers. Furthermore, the major impact of advances in genetics on risk prediction and biomarker development programs will be discussed.

FoxP1 stimulates angiogenesis by repressing the inhibitory guidance protein semaphorin 5B in endothelial cells

Forkhead box (Fox) transcription factors are important regulators of cardiovascular development and several Fox-proteins have recently been shown to modulate embryonic and post-natal angiogenesis. However, the role of the FoxP subfamily, which is highly expressed in cardiovascular tissue, has not been investigated so far. Here, we show that the transcription factor FoxP1 is the highest expressed FoxP-protein in endothelial cells and that it is upregulated at the site of neovascularization during hindlimb ischemia in mice. Silencing of FoxP1 results in a strong inhibition of proliferation, tube formation and migration of cultured endothelial cells. Accordingly, knockdown of FoxP1 in zebrafish was followed by a disruption of intersomitic vascular formation. Using gene expression profiling, we show that FoxP1 induces a specific change of the endothelial transcriptome and functions as a suppressor of semaphorin 5B, which has previously been described as a neuronal inhibitory factor. Our findings now demonstrate that semaphorin 5B also acts as a FoxP1- dependent suppressor of endothelial cell proliferation, migration and sprouting, mediating the effects of FoxP1. In summary, our data indicate that the transcription factor FoxP1 is essential for the angiogenic function of endothelial cells and functions as a suppressor of the inhibitory guidance cue semaphorin 5B, suggesting an important function of FoxP1 in the regulation of neovascularization.

Intracoronary infusion of allogeneic mesenchymal precursor cells directly after experimental acute myocardial infarction reduces infarct size, abrogates adverse remodeling, and improves cardiac function

RATIONALE

Mesenchymal precursor cells (MPCs) are a specific Stro-3+ subpopulation of mesenchymal stem cells isolated from bone marrow. MPCs exert extensive cardioprotective effects, and are considered to be immune privileged.

OBJECTIVE

This study assessed the safety, feasibility, and efficacy of intracoronary delivery of allogeneic MPCs directly after acute myocardial infarction in sheep.

METHODS AND RESULTS

Initially, intracoronary delivery conditions were optimized in 20 sheep. These conditions were applied in a randomized study of 68 sheep with an anterior acute myocardial infarction. Coronary flow was monitored during MPC infusion, and cardiac function was assessed using invasive hemodynamics and echocardiography at baseline and during 8 weeks follow-up. Coronary flow remained within thrombolysis in myocardial infarction III definitions in all sheep during MPC infusion. Global left ventricular ejection fraction as measured by pressure-volume loop analysis deteriorated in controls to 40.7±2.6% after 8 weeks. In contrast, MPC treatment improved cardiac function to 52.8±0.7%. Echocardiography revealed significant improvement of both global and regional cardiac functions. Infarct size decreased by 40% in treated sheep, whereas infarct and border zone thickness were enhanced. Left ventricular adverse remodeling was abrogated by MPC therapy, resulting in a marked reduction of left ventricular volumes. Blood vessel density increased by >50% in the infarct and border areas. Compensatory cardiomyocyte hypertrophy was reduced in border and remote segments, accompanied by reduced collagen deposition and apoptosis. No microinfarctions in remote myocardial segments or histological abnormalities in unrelated organs were found.

CONCLUSIONS

Intracoronary infusion of allogeneic MPCs is safe, feasible, and markedly effective in a large animal model of acute myocardial infarction.

The role of the Interleukin 1 receptor-like 1 (ST2) and Interleukin-33 pathway in cardiovascular disease and cardiovascular risk assessment

There is an ongoing search for biomarkers that can facilitate the diagnosis of subclinical or clinically manifest cardiovascular disease. One of the emerging biomarkers currently under investigation is ST2, which is the receptor of Interleukin-33 (IL-33). ST2 is a member of the Interleukin-1 receptor family and exists in a transmembrane (ST2L) and a soluble form (sST2) due to alternative splicing. Several groups have reported sST2 elevations in serum of cardiovascular disease patients. There is consisting evidence that sST2 is independently predictive for mortality in patients with heart failure or myocardial infarction. In addition to its potential as a biomarker for adverse cardiovascular events, ST2 is considered to play a causal role in chronic cardiovascular diseases such as atherosclerosis and heart failure. Signaling of IL-33 via ST2 has been shown to be cardioprotective in mouse models of myocardial infarction, heart transplantation and cardiac hypertrophy and fibrosis. Furthermore, treatment with IL-33 reduced the development of plaques in atherosclerotic mice. In this paper we will review the currently available literature on sST2 as a biomarker for adverse cardiovascular events. In addition, we will elaborate on the potential mechanistic role of the IL-33/ST2 pathway in chronic inflammatory cardiovascular diseases.

Feasibility of intracoronary GLP-1 eluting CellBead™ infusion in acute myocardial infarction

Cell therapy is a field of growing interest in the prevention of post acute myocardial infarction (AMI) heart failure. Stem cell retention upon local delivery to the heart, however, is still unsatisfactory. CellBeads were recently developed as a potential solution to this problem. CellBeads are 170-μm alginate microspheres that contain mesenchymal stem cells (MSCs) genetically modified to express glucagon-like peptide-1 (GLP-1) supplementary to inherent paracrine factors. GLP-1 is an incretin hormone that has both antiapoptotic and cardioprotective effects. Transplanting CellBeads in the post-AMI heart might induce cardiomyocyte salvage and ultimately abrogate adverse cardiac remodeling. We aimed to investigate the feasibility of intracoronary infusion of CellBeads in a large animal model of AMI. Four pigs were used in a pilot study to assess the maximal safe dose of CellBeads. In the remaining 21 animals, an AMI was induced by balloon occlusion of the left circumflex coronary artery for 90 min. During reperfusion, 60,000 CellBeads (n = 11), control beads (n = 4), or lactated Ringers' (n = 6) were infused. Animals were sacrificed after 2 or 7 days, and the hearts were excised for histological analyses. Intracoronary infusion did not permanently affect coronary flow in any of the groups. Histological analysis revealed CellBeads containing viable MSCs up to 7 days. Viability and activity of the MSCs was confirmed by qPCR analysis that showed expression of recombinant GLP-1 and human genes after 2 and 7 days. CellBeads reduced inflammatory infiltration by 29% (p = 0.001). In addition, they decreased the extent of apoptosis by 25% (p = 0.001) after 2 days. We show that intracoronary infusion of 5 million encapsulated MSCs is safe and feasible. Also, several parameters indicate that the cells have paracrine effects, suggesting a potential therapeutic benefit of this new approach.

Arteriogenesis Is Modulated By Bradykinin Receptor Signaling

Rationale:

Positive outward remodeling of pre-existing collateral arteries into functional conductance arteries, arteriogenesis, is a major endogenous rescue mechanism to prevent cardiovascular ischemia. Collateral arterial growth is accompanied by expression of kinin precursor. However, the role of kinin signaling via the kinin receptors (B1R and B2R) in arteriogenesis is unclear.

Objective:

The purpose of this study was to elucidate the functional role and mechanism of bradykinin receptor signaling in arteriogenesis.

Methods and Results:

Bradykinin receptors positively affected arteriogenesis, with the contribution of B1R being more pronounced than B2R. In mice, arteriogenesis upon femoral artery occlusion was significantly reduced in B1R mutant mice as evidenced by reduced microspheres and laser Doppler flow perfusion measurements. Transplantation of wild-type bone marrow cells into irradiated B1R mutant mice restored arteriogenesis, whereas bone marrow chimeric mice generated by reconstituting wild-type mice with B1R mutant bone marrow showed reduced arteriogenesis after femoral artery occlusion. In the rat brain 3-vessel occlusion arteriogenesis model, pharmacological blockade of B1R inhibited arteriogenesis and stimulation of B1R enhanced arteriogenesis. In the rat, femoral artery ligation combined with arterial venous shunt model resulted in flow-driven arteriogenesis, and treatment with B1R antagonist R715 decreased vascular remodeling and leukocyte invasion (monocytes) into the perivascular tissue. In monocyte migration assays, in vitro B1R agonists enhanced migration of monocytes.

Conclusions:

Kinin receptors act as positive modulators of arteriogenesis in mice and rats. B1R can be blocked or therapeutically stimulated by B1R antagonists or agonists, respectively, involving a contribution of peripheral immune cells (monocytes) linking hemodynamic conditions with inflammatory pathways.

Involvement of neuronal NO synthase in collateral artery growth

To evaluate the role of neuronal nitric oxides synthase (nNOS) in collateral artery growth (arteriogenesis), we analyzed the expression pattern of nNOS at distinct time points on RNA and protein levels in a rabbit and a murine model of peripheral arteriogenesis. In the rabbit model, Northern blot analyses revealed a significant upregulation of nNOS at 6 h (1.6-fold), 12 h (2.2-fold) and 24 h (2.0-fold) after induction of arteriogenesis via femoral artery ligation, when compared to the sham operated side. In mice, an upregulation of nNOS was also detected using Northern blot (at 6 h, 12 h) and qRT-PCR (12 h: 2.4-fold). On the protein level, nNOS was found to be upregulated 24 h after femoral artery ligation. Immunohistochemical staining showed that nNOS was localized in endothelial and smooth muscle cells of collateral arteries, as well as in skeletal muscle and nerves. In summary, our data provide evidence that nNOS is not constitutively expressed, but is induced during arteriogenesis, playing a role in supplying reactive oxygen species such as H2O2 and low levels of NO.

An animal paired crossover ePTFE arteriovenous graft model

PURPOSE

Previously, we developed a porcine model for Arterio Venous Graft (AVG) failure to allow assessment of new access strategies. This model was limited concerning graft length. In the present technical report, we describe a modification of our model allowing the assessment of long AVGs.

TECHNIQUE

In 4 pigs, AVGs of 15 cm length were created bilaterally in a cross-over fashion between the carotid artery and the contralateral jugular vein. Two days (2 pigs) and two weeks (2 pigs) after AV shunting, graft patency was evaluated by angiography, showing all four grafts to be patent, with no sign of angiographic or macroscopic narrowing at the anastomoses sites.

CONCLUSIONS

In this modified pig AVG failure model, implantation of a bilateral cross-over long AVG is a feasible approach. The present model offers a suitable tool to study local interventions or compare various long graft designs aimed at improvement of AVG patency.

Pulsatile shear and Gja5 modulate arterial identity and remodeling events during flow-driven arteriogenesis

In the developing chicken embryo yolk sac vasculature, the expression of arterial identity genes requires arterial hemodynamic conditions. We hypothesize that arterial flow must provide a unique signal that is relevant for supporting arterial identity gene expression and is absent in veins. We analyzed factors related to flow, pressure and oxygenation in the chicken embryo vitelline vasculature in vivo. The best discrimination between arteries and veins was obtained by calculating the maximal pulsatile increase in shear rate relative to the time-averaged shear rate in the same vessel: the relative pulse slope index (RPSI). RPSI was significantly higher in arteries than veins. Arterial endothelial cells exposed to pulsatile shear in vitro augmented arterial marker expression as compared with exposure to constant shear. The expression of Gja5 correlated with arterial flow patterns: the redistribution of arterial flow provoked by vitelline artery ligation resulted in flow-driven collateral arterial network formation and was associated with increased expression of Gja5. In situ hybridization in normal and ligation embryos confirmed that Gja5 expression is confined to arteries and regulated by flow. In mice, Gja5 (connexin 40) was also expressed in arteries. In the adult, increased flow drives arteriogenesis and the formation of collateral arterial networks in peripheral occlusive diseases. Genetic ablation of Gja5 function in mice resulted in reduced arteriogenesis in two occlusion models. We conclude that pulsatile shear patterns may be central for supporting arterial identity, and that arterial Gja5 expression plays a functional role in flow-driven arteriogenesis.

[Cytokine-eluting stents as new drug-delivery devices for angiogenic therapy]

The stimulation of the endogenous adaptive vessel growth (angiogenesis, arteriogenesis) provides a promising therapeutic approach for the large number of patients with vascular occlusive disease that is not eligible for current interventional treatments. Despite the proven efficacy of various factors in pre-clinical experimental studies, the successful translation of angiogenic therapies into clinical practice yet remains to be made. Most authors identified the mode of administrations as culprit for the neutral effects observed in the majority of clinical trials. Although experimental studies have proven the superiority of continuous intra-arterial application above other routes (iv, im, sc), clinical trials focused on either bolus therapy, iv or sc application respectively, due to the lack of technical solutions to fulfill the requirements of intra-arterial delivery. The recent developments in the field of drug eluting stents may offer new possibilities for local drug delivery. Local release of cytokines, such as TGF-beta, has been shown to induce collateral growth in an experimental model of PAD. Other factors might eventually render useful to stabilize atherosclerotic plaques downstream of the site of stent implantation.

Atherosclerotic lesion development and Toll like receptor 2 and 4 responsiveness

BACKGROUND

Toll like receptors (TLR) have been recognized for their role in atherosclerotic lesion development and progression. Endogenous TLR ligands that are also expressed in atherosclerotic tissues have been shown to promote atherosclerosis in mice. Since repetitive stimulation of TLR induces an attenuated inflammatory response, we hypothesized that the TLR response is altered during atherosclerosis development, due to chronic exposure to endogenous ligands.

METHODS AND RESULTS

We examined five groups of both ApoE-/- and C57Bl/6 mice aged 5, 10, 15, 25 and 40 weeks. In ApoE-/- mice with advanced stages of atherosclerosis, levels of mRNA encoding TLR2 and TLR4, the endogenous TLR ligands EDA and hsp60 as well as intracellular TLR-regulating mediators, like IRAK-M, were increased. Systemic TLR cell surface expression on circulating monocytes and EDA plasma levels were significantly increased in ApoE-/- mice with advanced atherosclerosis. We also observed that the endogenous TLR ligand EDA was capable of activating the TLR-signaling pathway in white blood cells. During the plaque progression stage however, stimulation of TLR2 and TLR4 in blood samples attenuated MIP-1 alpha and RANTES release in atherosclerotic mice.

CONCLUSION

During atherosclerotic lesion development, TLR2 and TLR4 expression increases in atherosclerotic plaques and on circulating blood cells. However, with advanced stages of atherosclerotic disease, circulating blood cells become less responsive to TLR ligation, which may be due to chronic TLR engagement by endogenous EDA.

Systemic application of anti-ICAM-1 monoclonal antibodies to prevent restenosis in rabbits: an anti-inflammatory strategy

OBJECTIVES

After vascular intervention, cell adhesion molecules such as ICAM-1 and VCAM are fundamental in inflammatory processes. In particular, ICAM-1 expression is strongly associated with macrophage-rich areas in restenotic lesions. Therefore, we hypothesized an anti-restenotic effect by systemic application of anti-ICAM-1 monoclonal antibodies (mAb).

METHODS

Thirty two rabbits underwent balloon angioplasty and stent implantation either in the right or left iliac artery, Animals received either anti-ICAM mAb or saline solution as a control. Animals were sacrificed 7 (n=8) and 14 (n=8) days and tissue was analyzed for basic fibroblast growth factor (bFGF) and transforming growth factor beta (TGF-beta) expression. Sixteen animals were sacrificed 6 months following treatment and tissue was harvested for histomorphometric analysis.

RESULTS

After balloon injury, bFGF significantly increased from 7 to 14 days only in the control group and was significantly higher compared to the anti-ICAM group. At 14 days after stent implantation, controls showed a significant increase of both bFGF and TGF-beta, whereas the anti-ICAM group only showed a significant increase of TGF-beta. Histomorphometric analysis for neointimal growth did not show any differences between control and anti-ICAM groups either after balloon injury or after stent implantation at 6 months.

CONCLUSION

Administration of anti-ICAM-1 mAb following either balloon angioplasty or stent implantation results in a suppression of bFGF in the early phase of restenosis, whereas TGF-beta significantly increases from 7 to 14 days after stent implantation independent of anti-ICAM-1 mAb application. Therefore we conclude that anti-inflammatory strategies are able to interfere with growth factor expression after vascular injury.

Granulocyte-macrophage colony-stimulating factor stimulates arteriogenesis in a pig model of peripheral artery disease using clinically applicable infusion pumps

BACKGROUND

A growing number of patients suffer from peripheral artery disease (PAD). Current therapies are often limited by the extent of vascular pathology and the occurrence of restenosis after angioplasty. The stimulatory effect of growth factor administration on collateral vessel formation (arteriogenesis) has evolved as a potential new treatment for this patient group. Granulocyte-macrophage colony-stimulating factor (GM-CSF) was shown to stimulate arteriogenesis in small-animal models and in a pilot study in patients with coronary artery disease. Although a recent clinical study demonstrated disappointing results after subcutaneous GM-CSF application in patients with PAD, we hypothesized that intra-arterial cytokine application using implantable infusion pumps might well stimulate arteriogenesis in a large-species model of peripheral vascular disease. We also aimed to compare continuous and intermittent infusion regimens and to validate experimental and clinically available measurements of collateral artery growth.

METHODS

Twenty-four pigs underwent unilateral occlusion of the right femoral artery and received either GM-CSF continuously, GM-CSF intermittently, or phosphate-buffered saline (PBS). After 1 week, collateral conductance was determined under maximal vasodilatation with adenosine and by using a pump-driven extracorporal shunt system.

RESULTS

Conductance showed a significant stimulatory effect of GM-CSF on arteriogenesis (collateral conductance [mL/min/mm Hg]: PBS, 37.7 +/- 5.4; GM-CSF continuous, 69.2 +/- 12.5; GM-CSF intermittent, 71.5 +/- 11.1). Flow measurements under reactive hyperemia were consistent with these results (flow occluded/non-occluded hind limb: PBS, 40.5% +/- 9.1%; GM-CSF continuous, 48.9% +/- 3.9%; GM-CSF intermittent, 48.7% +/- 4.4%). Measurements of ankle/brachial indices were not sensitive enough to detect the differences in collateral growth between the three groups.

CONCLUSION

These results demonstrate the proarteriogenic properties of GM-CSF in larger animal species, revealing comparable efficacy of continuous and intermittent intra-arterial infusion. Furthermore, we provide evidence that implantable pumps offer a possible means for the intra-arterial application of growth factors. Intra-arterial application of GM-CSF might be a future treatment option for vascular occlusive disease. Finally, we show that in the peripheral circulation, pressure measurements alone have a low sensitivity to determine the effects of proarteriogenic therapy compared with flow or combined flow-pressure measurements.

START Trial: a pilot study on STimulation of ARTeriogenesis using subcutaneous application of granulocyte-macrophage colony-stimulating factor as a new treatment for peripheral vascular disease

BACKGROUND

Granulocyte-macrophage colony-stimulating factor (GM-CSF) was recently shown to increase collateral flow index in patients with coronary artery disease. Experimental models showed beneficial effects of GM-CSF on collateral artery growth in the peripheral circulation. Thus, in the present study, we evaluated the effects of GM-CSF in patients with peripheral artery disease.

METHODS AND RESULTS

A double-blinded, randomized, placebo-controlled study was performed in 40 patients with moderate or severe intermittent claudication. Patients were treated with placebo or subcutaneously applied GM-CSF (10 microg/kg) for a period of 14 days (total of 7 injections). GM-CSF treatment led to a strong increase in total white blood cell count and C-reactive protein. Monocyte fraction initially increased but thereafter decreased significantly as compared with baseline. Both the placebo group and the treatment group showed a significant increase in walking distance at day 14 (placebo: 127+/-67 versus 184+/-87 meters, P=0.03, GM-CSF: 126+/-66 versus 189+/-141 meters, P=0.04) and at day 90. Change in walking time, the primary end point of the study, was not different between groups. No change in ankle-brachial index was found on GM-CSF treatment at day 14 or at day 90. Laser Doppler flowmetry measurements showed a significant decrease in microcirculatory flow reserve in the control group (P=0.03) and no change in the GM-CSF group.

CONCLUSIONS

The present study does not support the use of GM-CSF for treatment of patients with moderate or severe intermittent claudication. Issues that need to be addressed are dosing, the selection of patients, and potential differences between GM-CSF effects in the coronary and the peripheral circulation.

Anti-tumor necrosis factor-{alpha} therapies attenuate adaptive arteriogenesis in the rabbit

The specific antagonists of tumor necrosis factor-alpha (TNF-alpha), infliximab and etanercept, are established therapeutic agents for inflammatory diseases such as rheumatoid arthritis and Crohn's disease. Although the importance of TNF-alpha in chronic inflammatory diseases is well established, little is known about its implications in the cardiovascular system. Because proliferation of arteriolar connections toward functional collateral arteries (arteriogenesis) is an inflammatory-like process, we tested in vivo the hypothesis that infliximab and etanercept have antiarteriogenic actions. Sixty-three New Zealand White rabbits underwent femoral artery occlusion and received infliximab, etanercept, or vehicle according to clinical dosage regimes. After 1 wk, collateral conductance, assessed with fluorescent microspheres, revealed significant inhibition of arteriogenesis (collateral conductance): 52.4 (SD 8.1), 35.2 (SD 7.7), and 33.3 (SD 10.1) ml x min(-1) x 100 mmHg(-1) with PBS, infliximab, and etanercept, respectively (P < 0.001). High-resolution angiography showed no significant differences in number of collateral arteries, but immunohistochemical analysis demonstrated a decrease in mean collateral diameter, proliferation of vascular smooth muscle cells, and reduction of leukocyte accumulation around collateral arteries in treated groups. Infliximab and etanercept bound to infiltrating leukocytes, which are important mediators of arteriogenesis. Infliximab induced monocyte apoptosis, and neither substance affected monocyte expression of the adhesion molecule Mac-1. We demonstrated that TNF-alpha serves as a pivotal modulator of arteriogenesis, which is attenuated by treatment with TNF-alpha inhibitors. Reduction of collateral conductance is most likely due to inhibition of perivascular leukocyte infiltration and subsequent lower vascular smooth muscle cell proliferation. This is the first report showing a negative influence of TNF-alpha inhibitors on collateral artery growth.

CD44 Regulates Arteriogenesis in Mice and Is Differentially Expressed in Patients With Poor and Good Collateralization

Background— Arteriogenesis refers to the development of collateral conductance arteries and is orchestrated by circulating monocytes, which invade growing collateral arteries and act as suppliers of cytokines and growth factors. CD44 glycoproteins are involved in leukocyte extravasation but also in the regulation of growth factor activation, stability, and signaling. Here, we explored the role of CD44 during arteriogenesis.

Methods and Results— CD44 expression increases strongly during collateral artery growth in a murine hind-limb model of arteriogenesis. This CD44 expression is of great functional importance, because arteriogenesis is severely impaired in CD44 −/− mice (wild-type, 54.5±14.9% versus CD44 −/− , 24.1±9.2%, P <0.001). The defective arteriogenesis is accompanied by reduced leukocyte trafficking to sites of collateral artery growth (wild-type, 29±12% versus CD44 −/− , 18±7% CD11b-positive cells/square, P <0.01) and reduced expression of fibroblast growth factor-2 and platelet-derived growth factor-B protein. Finally, in patients with single-vessel coronary artery disease, the maximal expression of CD44 on activated monocytes is reduced in case of impaired collateral artery formation (poor collateralization, 1764±572 versus good collateralization, 2817±1029 AU, P <0.05).

Conclusions— For the first time, the pivotal role of CD44 during arteriogenesis is shown. The expression of CD44 increases during arteriogenesis, and the deficiency of CD44 severely impedes arteriogenesis. Maximal CD44 expression on isolated monocytes is decreased in patients with a poor collateralization compared with patients with a good collateralization.