New molecular strategies for prevention of fibroproliferative vascular disease : An experimental approach to restenosis

Vascular intimal hyperplasia is a major complication following angioplasty. The hallmark feature of this disorder is accumulation of dedifferentiated smooth muscle cells (SMCs) to the luminal side of the injured artery, cellular proliferation, migration, and synthesis of extracellular matrix. This finally results in intimal hyperplasia, which is currently considered an untreatable condition. According to current knowledge, a major part of neointimal cells derive from circulating precursor cells. This has outdated the traditional in vitro cell culture methods of studying neointimal cell migration and proliferation using cultured medial SMCs. Somatostatin and some of its analogs with different selectivity for the five somatostatin receptors (sst1 through sst5) have been shown to have vasculoprotective properties in animal studies. However, clinical trials using analogs selective for sst2/sst3/sst5 to prevent restenosis after percutaneous transluminal coronary angioplasty (PTCA) have failed to show any major benefits. Sirolimus is a cell cycle inhibitor that has been suggested to act synergistically with the protein-tyrosine kinase inhibitor imatinib to inhibit intimal hyperplasia in rat already at well-tolerated submaximal oral doses. The mechanisms behind this synergy and its long-term efficacy are not known. The aim of this study was to set up an ex vivo vascular explant culture model to measure neointimal cell activity without excluding the participation of circulating progenitor cells. Furthermore, two novel potential vasculoprotective treatment strategies were evaluated in detail in rat models of intimal hyperplasia and in the ex vivo explant model: sst1/sst4-selective somatostatin receptor analogs and combination treatment with sirolimus and imatinib. This study shows how whole vessel explants can be used to study the kinetics of neointimal cells and their progenitors, and to evaluate the anti-migratory and anti-proliferative properties of potential vasculoprotective compounds. It also shows how the influx of neointimal progenitor cells occurs already during the first days after vascular injury, how the contribution of cell migration is more important in the injury response than cell proliferation, and how the adventitia actively contribute in vascular repair. The vasculoprotective effect of somatostatin is mediated preferentially through sst4, and through inhibition of cell migration rather than of proliferation, which may explain why sst2/sst3/sst5-selective analogs have failed in clinical trials. Furthermore, a brief early oral treatment with the combination of sirolimus and imatinib at submaximal doses results in long-term synergistic suppression of intimal hyperplasia. The synergy is a result of inhibition of post-operative thrombocytosis and leukocytosis, inhibition of neointimal cell migration to the injury-site, and maintenance of cell integrity by inhibition of apoptosis and SMC dedifferentiation. In conclusion, the influx of progenitor cells already during the first days after injury and the high neointimal cell migratory activity underlines the importance of early therapeutic intervention with anti-migratory compounds to prevent neointimal hyperplasia. Sst4-selective analogs and the combination therapy with sirolimus and imatinib represent potential targets for the development of such vasculoprotective therapies.

Endothelial Progenitors as Tools to Study Vascular Disease

Endothelial progenitor cells (EPCs) have great clinical value because they can be used as diagnostic biomarkers and as a cellular therapy for promoting vascular repair of ischaemic tissues. However, EPCs also have an additional research value in vascular disease modelling to interrogate human disease mechanisms. The term EPC is used to describe a diverse variety of cells, and we have identified a specific EPC subtype called outgrowth endothelial cell (OEC) as the best candidate for vascular disease modelling because of its high-proliferative potential and unambiguous endothelial commitment. OECs are isolated from human blood and can be exposed to pathologic conditions (forward approach) or be isolated from patients (reverse approach) in order to study vascular human disease. The use of OECs for modelling vascular disease will contribute greatly to improving our understanding of endothelial pathogenesis, which will potentially lead to the discovery of novel therapeutic strategies for vascular diseases.

Epigenetics in Vascular Disease - Therapeutic Potential of New Agents

Vascular diseases, including atherosclerosis, angioplasty-induced restenosis, vessel graft arteriosclerosis and hypertension-related stenosis, remain the most prevalent cause of death in the developed world. The aetiology of vascular diseases is multifactorial with both genetic and environmental factors. Recently, some of the most promising research identifies the epigenetic modification of the genome to play a major role in the disease development, linking the environmental insults with gene regulation. In this process, modification of DNA by methylation, and histone modification by acetylation, methylation, phosphorylation and/or SUMOylation are reported. Importantly, recent studies demonstrated that histone deacetylase (HDAC) enzymes are crucial in endothelial integrity, smooth muscle proliferation and in the formation of arteriosclerosis in animal models. The study of HDACs has shown remarkable specificity of HDAC family members in vascular cell growth/death that influences the disease process. Interestingly, the effects of HDACs on arteriosclerosis development in animal models have been observed after HDAC inhibition using specific inhibitors. This provides a new approach for the treatment of vascular disease using the agents that influence the epigenetic process in vascular cells. This review updates the rapid advances in epigenetics of vascular diseases focusing on the role of HDAC family in atherosclerosis. It will also discuss the underlying mechanisms of histone acetylation in vascular cells and highlight the therapeutic potential of such agents.

The consumption of milk and dairy foods and the incidence of vascular disease and diabetes: An overview of the evidence

The health effects of milk and dairy food consumption would best be determined in randomised controlled trials. No adequately powered trial has been reported and none is likely because of the numbers required. The best evidence comes, therefore, from prospective cohort studies with disease events and death as outcomes. Medline was searched for prospective studies of dairy food consumption and incident vascular disease and Type 2 diabetes, based on representative population samples. Reports in which evaluation was in incident disease or death were selected. Meta-analyses of the adjusted estimates of relative risk for disease outcomes in these reports were conducted. Relevant case–control retrospective studies were also identified and the results are summarised in this article. Meta-analyses suggest a reduction in risk in the subjects with the highest dairy consumption relative to those with the lowest intake: 0.87 (0.77, 0.98) for all-cause deaths, 0.92 (0.80, 0.99) for ischaemic heart disease, 0.79 (0.68, 0.91) for stroke and 0.85 (0.75, 0.96) for incident diabetes. The number of cohort studies which give evidence on individual dairy food items is very small, but, again, there is no convincing evidence of harm from consumption of the separate food items. In conclusion, there appears to be an enormous mis-match between the evidence from long-term prospective studies and perceptions of harm from the consumption of dairy food items.

Milk in the diet: good or bad for vascular disease?

CVD still represent the greatest cause of death and disease burden in Europe and there remains uncertainty whether or not diets rich in milk and/or dairy products affect CVD risk. This paper reviews current evidence on this from prospective studies and the role of serum lipids and blood pressure as markers of CVD risk with such diets. Also the potential of animal nutrition-based approaches aimed at reducing CVD risk from consumption of milk and dairy products is outlined. Briefly, the evidence from prospective studies indicates that increased consumption of milk does not result in increased CVD risk and may give some long-term benefits, although few studies relate specifically to cheese and butter and more information on the relationship between milk/dairy product consumption and dementia is needed. Recent data suggest that the SFA in dairy products may be less of a risk factor than previously thought; although this is based on serum cholesterol responses which taken in isolation may be misleading. Milk and some dairy products have counterbalancing effects by reducing blood pressure and possibly BMI control. Despite this, animal nutrition strategies to replace some SFA in milk with cis-MUFA or cis-PUFA are extensive and intuitively beneficial, although this remains largely unproven, especially for milk. There is an urgent need for robust intervention studies to evaluate such milk-fat modifications using holistic markers of CVD risk including central arterial stiffness.

An artificial nanoemulsion carrying paclitaxel decreases the transplant heart vascular disease: A study in a rabbit graft model

Objective: In previous studies cholesterol-rich nanoemulsions (LDE) resembling low-density lipoprotein were shown to concentrate in atherosclerotic lesions of rabbits. Lesions were pronouncedly reduced by treatment with paclitaxel associated with LDE. This study aimed to test the hypothesis of whether LDE-paclitaxel is able to concentrate in grafted hearts of rabbits and to ameliorate coronary allograft vasculopathy after the transplantation procedure. Methods: Twenty-one New Zealand rabbits fed 0.5% cholesterol were submitted to heterotopic heart transplantation at the cervical position. All rabbits undergoing transplantation were treated with cyclosporin A (10 mg . kg(-1) . d(-1) by mouth). Eleven rabbits were treated with LDE-paclitaxel (4 mg/kg body weight paclitaxel per week administered intravenously for 6 weeks), and 10 control rabbits were treated with 3 mL/wk intravenous saline. Four control animals were injected with LDE labeled with [(14)C]-cholesteryl oleate ether to determine tissue uptake. Results: Radioactive LDE uptake by grafts was 4-fold that of native hearts. In both groups the coronary arteries of native hearts showed no stenosis, but treatment with LDE-paclitaxel reduced the degree of stenosis in grafted hearts by 50%. The arterial luminal area in grafts of the treated group was 3-fold larger than in control animals. LDE-paclitaxel treatment resulted in a 7-fold reduction of macrophage infiltration. In grafted hearts LDE-paclitaxel treatment reduced the width of the intimal layer and inhibited the destruction of the medial layer. No toxicity was observed in rabbits receiving LDE-paclitaxel treatment. Conclusions: LDE-paclitaxel improved posttransplantation injury to the grafted heart. The novel therapeutic approach for heart transplantation management validated here is thus a promising strategy to be explored in future clinical studies. (J Thorac Cardiovasc Surg 2011;141:1522-8)

Factors influencing participation in a vascular disease prevention lifestyle program among participants in a cluster randomized trial

Background
Previous research suggests that lifestyle intervention for the prevention of diabetes and cardiovascular disease (CVD) are effective, however little is known about factors affecting participation in such programs. This study aims to explore factors influencing levels of participation in a lifestyle modification program conducted as part of a cluster randomized controlled trial of CVD prevention in primary care.

Methods
This concurrent mixed methods study used data from the intervention arm of a cluster RCT which recruited 30 practices through two rural and three urban primary care organizations. Practices were randomly allocated to intervention (n = 16) and control (n = 14) groups. In each practice up to 160 eligible patients aged between 40 and 64 years old, were invited to participate. Intervention practice staff were trained in lifestyle assessment and counseling and referred high risk patients to a lifestyle modification program (LMP) consisting of two individual and six group sessions over a nine month period. Data included a patient survey, clinical audit, practice survey on capacity for preventive care, referral and attendance records at the LMP and qualitative interviews with Intervention Officers facilitating the LMP. Multi-level logistic regression modelling was used to examine independent predictors of attendance at the LMP, supplemented with qualitative data from interviews with Intervention Officers facilitating the program.

Results
A total of 197 individuals were referred to the LMP (63% of those eligible). Over a third of patients (36.5%) referred to the LMP did not attend any sessions, with 59.4% attending at least half of the planned sessions. The only independent predictors of attendance at the program were employment status - not working (OR: 2.39 95% CI 1.15-4.94) and having high psychological distress (OR: 2.17 95% CI: 1.10-4.30). Qualitative data revealed that physical access to the program was a barrier, while GP/practice endorsement of the program and flexibility in program delivery facilitated attendance.

Conclusion
Barriers to attendance at a LMP for CVD prevention related mainly to external factors including work commitments and poor physical access to the programs rather than an individuals’ health risk profile or readiness to change. Improving physical access and offering flexibility in program delivery may enhance future attendance. Finally, associations between psychological distress and attendance rates warrant further investigation.

Implementing guidelines to routinely prevent chronic vascular disease in primary care: the preventive evidence into practice cluster randomised controlled trial

Objective: To evaluate an intervention to improve implementation of guidelines for the prevention of chronic vascular disease. Setting: 32 urban general practices in 4 Australian states. Randomisation: Stratified randomisation of practices. Participants: 122 general practitioners (GPS) and practice nurses (PNs) were recruited at baseline and 97 continued to 12 months. 21 848 patient records were audited for those aged 40-69 years who attended the practice in the previous 12 months without heart disease, stroke, diabetes, chronic renal disease, cognitive impairment or severe mental illness. Intervention: The practice level intervention over 6 months included small group training of practice staff, feedback on audited performance, practice facilitation visits and provision of patient education and referral information. Outcome measures: Primary: 1. Change in proportion of patients aged 40-69 years with smoking status, alcohol intake, body mass index (BMI), waist circumference (WC), blood pressure (BP) recorded and for those aged 45-69 years with lipids, fasting blood glucose and cardiovascular risk in the medical record. 2. Change in the level of risk for each factor. Secondary: change in self-reported frequency and confidence of GPS and PNs in assessment. Results: Risk recording improved in the intervention but not the control group for WC (OR 2.52 (95% CI 1.30 to 4.91)), alcohol consumption (OR 2.19 (CI 1.04 to 4.64)), smoking status (OR 2.24 (1.17 to 4.29)) and cardiovascular risk (OR 1.50 (1.04 to 2.18)). There was no change in recording of BP, lipids, glucose or BMI and no significant change in the level of risk factors based on audit data. The confidence but not reported practices of GPS and PNs in the intervention group improved in the assessment of some risk factors. Conclusions: This intervention was associated with improved recording of some risk factors but no change in the level of risk at the follow-up audit. Trial registration number: Australian and New Zealand Clinical Trials Register (ANZCTR): ACTRN12612000578808, results.

Health improvement and prevention study (HIPS) - evaluation of an intervention to prevent vascular disease in general practice

Background

The Health Improvement and Prevention Study (HIPS) study aims to evaluate the capacity of general practice to identify patients at high risk for developing vascular disease and to reduce their risk of vascular disease and diabetes through behavioural interventions delivered in general practice and by the local primary care organization.

Methods/Design

HIPS is a stratified randomized controlled trial involving 30 general practices in NSW, Australia. Practices are randomly allocated to an 'intervention' or 'control' group. General practitioners (GPs) and practice nurses (PNs) are offered training in lifestyle counselling and motivational interviewing as well as practice visits and patient educational resources. Patients enrolled in the trial present for a health check in which the GP and PN provide brief lifestyle counselling based on the 5As model (ask, assess, advise, assist, and arrange) and refer high risk patients to a diet education and physical activity program. The program consists of two individual visits with a dietician or exercise physiologist and four group sessions, after which patients are followed up by the GP or PN. In each practice 160 eligible patients aged between 40 and 64 years are invited to participate in the study, with the expectation that 40 will be eligible and willing to participate. Evaluation data collection consists of (1) a practice questionnaire, (2) GP and PN questionnaires to assess preventive care attitudes and practices, (3) patient questionnaire to assess self-reported lifestyle behaviours and readiness to change, (4) physical assessment including weight, height, body mass index (BMI), waist circumference and blood pressure, (5) a fasting blood test for glucose and lipids, (6) a clinical record audit, and (7) qualitative data collection. All measures are collected at baseline and 12 months except the patient questionnaire which is also collected at 6 months. Study outcomes before and after the intervention is compared between intervention and control groups after adjusting for baseline differences and clustering at the level of the practice.

Discussion

This study will provide evidence of the effectiveness of a primary care intervention to reduce the risk of cardiovascular disease and diabetes in general practice patients. It will inform current policies and programs designed to prevent these conditions in Australian primary health care.

Predictors of primary care referrals to a vascular disease prevention lifestyle program among participants in a cluster randomised trial

Background

Cardiovascular disease accounts for a large burden of disease, but is amenable to prevention through lifestyle modification. This paper examines patient and practice predictors of referral to a lifestyle modification program (LMP) offered as part of a cluster randomised controlled trial (RCT) of prevention of vascular disease in primary care.

Methods

Data from the intervention arm of a cluster RCT which recruited 36 practices through two rural and three urban primary care organisations were used. In each practice, 160 eligible high risk patients were invited to participate. Practices were randomly allocated to intervention or control groups. Intervention practice staff were trained in screening, motivational interviewing and counselling and encouraged to refer high risk patients to a LMP involving individual and group sessions. Data include patient surveys; clinical audit; practice survey on capacity for preventive care; referral records from the LMP. Predictors of referral were examined using multi-level logistic regression modelling after adjustment for confounding factors.

Results

Of 301 eligible patients, 190 (63.1%) were referred to the LMP. Independent predictors of referral were baseline BMI ≥ 25 (OR 2.87 95%CI:1.10, 7.47), physical inactivity (OR 2.90 95%CI:1.36,6.14), contemplation/preparation/action stage of change for physical activity (OR 2.75 95%CI:1.07, 7.03), rural location (OR 12.50 95%CI:1.43, 109.7) and smaller practice size (1–3 GPs) (OR 16.05 95%CI:2.74, 94.24).

Conclusions

Providing a well-structured evidence-based lifestyle intervention, free of charge to patients, with coordination and support for referral processes resulted in over 60% of participating high risk patients being referred for disease prevention. Contrary to expectations, referrals were more frequent from rural and smaller practices suggesting that these practices may be more ready to engage with these programs.