Advances in Design and Development of Lumi-Solve: A Novel Drug-Eluting Photo-Angioplasty Device.

PURPOSE: The Lumi-Solve photo-angioplasty drug eluting balloon catheter (DEBc) may afford safety advantages over current DEBc. Lumi-Solve utilises the guidewire (GW) port and lumen to deliver fibre-optic UV365nm light to the angioplasty balloon which may be problematic. We explore and evaluate alternative Lumi-Solve design options to circumvent fibre-optic use of the GW port and lumen which may enhance efficacy and clinical utility. METHODS: Effects of guidewire shadowing (GWS) on visible and UV365nm light transmission were evaluated and modelled in-silico. To evaluate the effect of a dedicated intra-balloon fibre-optic port, modified angioplasty balloons and sections of translucent polyethylene terephthalate (PET) GW port tubing were utilised. Investigation of the effect of GWS on chemical and biological photo-activation of balloon surface drug was performed utilising LCMS analysis and inhibition of histone deacetylase activity (HDACi) was measured in human umbilical vein endothelial cells (HUVEC). RESULTS: Parallel fibre-optic and GW port configurations generated a GWS of approximately 18.0% of the evaluable balloon surface area and attenuated both visible and UV light intensity by 20.0-25.0% and reduced chemical photo-activation of balloon surface drug and HDACi by at least 40-45%. Alternative fibre-optic port configurations including a spiral design significantly mitigated GWS effects on UV light transmission. CONCLUSIONS: To avoid use of the GW port and its associated complications a dedicated third port and lumen for the Lumi-Solve fibre-optic may be required. To maximize balloon surface chemical and biological photo-activation, non-parallel, intra-balloon, fibre-optic lumen trajectories, including a spiral design may be useful.

Fibromuscular Dysplasia: Three Cases to Highlight a Requirement for Surveillance Strategy Optimization.

Fibromuscular dysplasia (FMD) is a rare vascular disease with broad, potentially severe complications. We present three cases of FMD covering the spectrum of clinical presentations involving the abdominal and visceral vasculature, and highlight the potential role of high-risk genotype detection in assisting with the determination of which patients may benefit from a more aggressive surveillance strategy.

A pilot clinical study to Evaluate Liraglutide-mediated Anti-platelet activity in patients with type-2 Diabetes (ELAID study).

BACKGROUND: Liraglutide is an effective treatment for the management of type 2 diabetes mellitus (T2DM). In addition to glycemic control and potential cardioprotective effects, recent studies suggest a possible role for liraglutide in the inhibition of platelet reactivity, further attenuating atherothrombotic risk in patients with T2DM. We evaluated the in-vivo antiplatelet effect of liraglutide in T2DM patients without macrovascular disease or concurrent anti-platelet therapy. METHODS: A double-blind, placebo-controlled pilot study of 16 T2DM patients, 51-69 y/o, (mean age 60.4 y/o, 63.0% male) randomised to receive liraglutide (1.8 mg/day) or placebo (saline) for 6 months was conducted. Platelet aggregation studies at baseline and after initiation of the study intervention: days 1, 7, and 14 and months 1, 3 and 6 were performed. RESULTS: Liraglutide (n = 7) and placebo (n = 9) treated patients demonstrated normal platelet aggregation responses although transient and significant attenuation in maximum slope of platelet aggregation in response to collagen (p ≤ 0.05), arachidonic acid (p ≤ 0.05) and ADP (p ≤ 0.02) was observed in liraglutide compared to placebo treated patients in the first week. CONCLUSIONS: In this pilot study of patients with T2DM liraglutide treatment was associated with a significant, early and transient decrease in maximum slope of platelet aggregation. The clinical significance of this effect is currently unknown and may warrant further investigation. CLINICAL TRIAL REGISTRATION NUMBER: UTN 1111-1181-9567.

Point of care ankle pulse waveform: A biomarker for abdominal aortic aneurysm?

OBJECTIVE: To explore the potential relationship between the presence of abdominal aortic aneurysm and point of care ankle brachial index acquired posterior tibial artery Doppler waveform to inform on a potential novel biomarker of abdominal aortic aneurysm presence. METHODS: Abdominal aortic aneurysm presence and posterior tibial artery waveform acquired at time of routine point of care ankle brachial index were determined in 182 patients from an abdominal aortic aneurysm evaluation vascular outpatient clinic. Multivariate technical random forest analysis and logistical regression analysis assessed the outcome of abdominal aortic aneurysm presence and included the independent variables of monophasic initial posterior tibial artery waveform and known abdominal aortic aneurysm risk factors. RESULTS: Technical random forest analysis produced a model with an accuracy of 0.59. Initial waveform phase was the most important variable included in the model. Logistical regression analysis revealed a statistically significant negative association between initial monophasic posterior tibial artery waveform and abdominal aortic aneurysm presence in patients with ankle brachial index > 0.9. Leave one out cross validation analysis produced a bias-corrected prediction error value of 0.22. CONCLUSION: No robust association between abdominal aortic aneurysm and point of care ankle brachial index acquired posterior tibial artery waveform was found, suggesting that monophasic posterior tibial artery waveform alone may not be a biomarker of abdominal aortic aneurysm presence.

Design, Development, In Vitro and Preliminary In Vivo Evaluation of a Novel Photo-Angioplasty Device: Lumi-Solve.

PURPOSE: Paclitaxel (PTX)-coated drug eluting balloon catheters (DEBc) used in the management of neointimal hyperplasia (NIH) have been associated with safety concerns. Alternative coating agents and targeted delivery systems may improve safety and DEBc efficacy. Utilizing a multi-platform approach we designed, developed and evaluated Lumi-Solve, a novel DEBc, coated with ultraviolet (UV) 365 nm-activated caged metacept-3 (c-MCT-3), an epigenetic agent from the histone deacetylase inhibitor (HDACi) class. METHODS: In vitro catheter and contrast media transmission of UV365nm was evaluated spectroscopically. UV365nm conversion of c-MCT-3 to MCT-3 was evaluated chromatographically. Cellular toxicity and HDACi activity of c-MCT-3 ∓UV365nm was evaluated in vitro. In vivo UV365nm conversion of c-MCT-3 to MCT-3 was evaluated in an ovine carotid artery model. RESULTS: Catheter material and dilute contrast media did not attenuate UV365nm transmission or c-MCT-3 activation. c-MCT-3 demonstrated less cellular toxicity than MCT-3 and PTX. UV365nm-activated c-MCT-3 demonstrated HDACi activity. In vivo activation of c-MCT-3 produced MCT-3. CONCLUSIONS: Lumi-Solve, a novel DEBc device developed utilizing a combination of chemical, fibre-optic and catheter based technology platforms, demonstrated potential for targeted delivery of bioactive HDACi to the blood vessel wall supporting direct application to the management of NIH and warranting additional in vivo studies.

Synthesis and biological evaluation of a novel photo-activated histone deacetylase inhibitor.

Hydroxamic acid-based histone deacetylase inhibitors (HDACi) are a class of epigenetic agents with potentially broad therapeutic application to several disease states including post angioplasty mediated neointimal hyperplasia (NIH). Precise spatiotemporal control over the release of HDACi at the target blood vessel site is required for the safe and successful therapeutic use of HDACi in the setting of drug eluting balloon catheter (DEBc) angioplasty treatment of NIH. We aimed to develop and characterise a novel photoactive HDACi, as a potential coating agent for DEBc. Metacept-3 1 was caged with a photo-labile protecting group (PPG) to synthesise a novel UV365nm active HDACi, caged metacept-3 15. Conversion of caged metacept-3 15 to active/native metacept-3 1 by UV365nm was achievable in significant quantities and at UV365nm power levels in the milliwatt (mW) range. In vitro evaluation of the biological activity of pre and post UV365nm activation of caged metacept-3 15 identified significant HDACi activity in samples exposed to short duration, mW range UV365nm. Toxicity studies performed in human umbilical vein endothelial cells (HUVEC's) identified significantly reduced toxicity of caged metacept-3 15 pre UV365nm exposure compared with native metacept-3 1 and paclitaxel (PTX). Taken together these findings identify a novel photo-activated HDACi, caged metacept-3 15, with pharmacokinetic activation characteristics and biological properties which may make it suitable for evaluation as a novel coating for targeted DEBc angioplasty interventions.

A Novel Epigenetic Drug-Eluting Balloon Angioplasty Device: Evaluation in a Large Animal Model of Neointimal Hyperplasia.

PURPOSE: Drug-eluting balloon catheters (DEBc) coated with paclitaxel (PTX) have been associated with potential safety concerns. An efficacious but less toxic balloon coating may reduce these outcomes. We evaluated a novel DEBc, Epi-Solve, coated with metacept-3 (MCT-3), a member of the histone deacetylase inhibitor (HDACi) class of epigenetic agents, in a large animal model of neointimal hyperplasia (NIH). METHODS: Plain balloon angioplasty (PABA) catheters were ultrasonically coated with MCT-3 to generate Epi-Solve DEBc. An ovine model of NIH formation was established utilising partial left common carotid artery (LCA) ligation. Twenty-eight days post neointima (NI) induction, PABA, Epi-Solve or PTX-coated DEBc were deployed at the site of induced NI formation. Twenty-eight days post-intervention, ligated vessels were evaluated for attenuation of NI formation, gene expression profiles and immunohistochemical analysis. RESULTS: Epi-Solve DEBc demonstrated attenuation of NIH over no intervention and a trend to inhibition of NIH over PABA. Gene expression analysis and immunohistochemical studies identified significant anti-proliferative and anti-inflammatory signatures and reduced vascular endothelial cell activation compared to PABA. CONCLUSIONS: Epi-Solve is a novel HDACi-coated DEBc which demonstrates significant anti-proliferative and anti-inflammatory signatures and reduced vascular endothelial cell activation compared to PABA in an ovine model and may afford endothelial protection.

Epigenetic treatment-mediated modulation of PD-L1 predicts potential therapy resistance over response markers in myeloid malignancies: A molecular mechanism involving effectors of PD-L1 reverse signaling.

Recent evidence suggests an association exists between resistance to epigenetic therapy (EGT) and the expression of programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1) in myeloid malignancies. Biomarkers are required to predict resistance to EGT in myeloid malignancies, which together with the delineation of associated molecular mechanisms, may provide additional understanding for novel treatment strategies when investigating resistance to EGT. The present study aimed to investigate the in vivo effects of EGT on the expression of PD-1, PD-L1 and orphan nuclear receptor NUR77 with clinical responses in patients with myeloid malignancies. In addition, in vitro and in vivo characterization of the effects of EGT on the expression of NF-κB and Bcl-xL, potential downstream targets of PD-L1 reverse signaling, were evaluated to determine components of the molecular mechanism responsible for these effects. The in vivo effects of EGT on the expression of PD-1, PD-L1 and a previously identified molecular marker of response to EGT, NUR77 was characterized in peripheral blood mononuclear cells (PBMC) from patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) treated with either azacytidine (Aza) alone or a combination of Aza and the histone deacetylase inhibitor (HDACi) LBH-589 during the first cycle of therapy. The correlation of clinical responses to treatment with EGT with the expression of PD-1, PD-L1 and NUR77 demonstrated that the induction of PD-L1 mRNA levels was associated with resistance to EGT despite the concurrent augmentation of NUR77 expression. The characterization of potential downstream effector molecules of reverse PD-L1 signaling identified EGT-mediated induction of Bcl-xL and NF-κB mRNA expression in vitro and in vivo, suggesting a potential anti-apoptotic molecular mechanism was responsible for PD-L1-mediated resistance to EGT. Taken together, these observations suggest that enhanced PD-L1 expression may confer resistance to EGT over known EGT response markers in myeloid malignancies, and provides a potential molecular mechanism involving the modulation of effectors of PD-L1 reverse signaling, which may in-part, be responsible for these effects.

Dapagliflozin attenuates human vascular endothelial cell activation and induces vasorelaxation: A potential mechanism for inhibition of atherogenesis.

BACKGROUND: Sodium glucose transporter type 2 inhibitors may reduce cardiovascular events in type 2 diabetes. Our study aimed to determine the effect of the sodium glucose transporter type 2 inhibitor dapagliflozin on endothelial cell activation, vasoreactivity and atherogenesis using in vitro and in vivo models and identify associated molecular mechanisms. METHODS: In vitro studies utilised human vascular endothelial cells stimulated with tumour necrosis factor α or hyperglycaemic conditions. In vivo studies were performed in C57Bl/6J mice to evaluate direct vasorelaxation responses evoked by acute dapagliflozin administration and acute vaso-protective effects of dapagliflozin on hyperglycaemia-induced endothelial dysfunction. Adult and aged Apolipoprotein E-deficient mice maintained on a high-fat diet were used to investigate endothelial-dependent vascular reactivity and atherogenesis. Dapagliflozin treatment (1.0 mg/kg/day) was administered for 4 weeks. RESULTS: In vitro studies demonstrated dapagliflozin-mediated attenuation of tumour necrosis factor α- and hyperglycaemia-induced increases in intercellular adhesion molecule-1, vascular cell adhesion molecule-1, plasminogen activator inhibitor type 1 and NFκB expression. Acute dapagliflozin administration dose-dependently induced endothelium-independent vasorelaxation. Chronic dapagliflozin treatment improved endothelial function and significantly reduced in vivo vascular adhesion molecule and phospho-IκB expression together with macrophage vessel wall infiltration. CONCLUSION: These observations identify a potential role for dapagliflozin in the attenuation of atherogenesis and identify anti-inflammatory molecular mechanisms associated with these effects.

Current and emerging pharmacotherapies for obesity in Australia.

BACKGROUND: Obesity is a major issue in Australia and globally. Many individuals struggle to maintain weight loss with lifestyle modification, and adjunctive pharmacotherapy may help. Historically, there have been limited pharmacotherapies for managing obesity. In addition, previous treatments such as phentermine-fenfluramine, rimonabant and sibutramine were withdrawn due to safety issues, resulting in lingering safety concerns. METHODS: This is a narrative review of published data examining four new pharmacotherapy options for weight management in Australia. Of four new therapeutic options, three may be approved in Australia shortly and one - liraglutide 3.0mg - was approved in December 2015. Liraglutide is a glucagon-like peptide-1 receptor agonist that appears to act by increasing satiety and reducing food intake. Lorcaserin is a selective agonist of the serotonin2C receptor, which mediates anorectic activity. The naltrexone/bupropion extended release (ER) combination utilises synergistic effects of the two component drugs, mediated via neurons in the hypothalamus, to reduce energy intake. Phentermine/topiramate ER combines the appetite suppressant phentermine with topiramate, an anti-epileptic with appetite-suppressant effects. All can result in meaningful improvements in obesity-related diseases, including diabetes and cardiovascular disorders) in large phase 3 trials, with efficacy demonstrated over 3 years for liraglutide 3.0 mg and 1-2 years for the rest. CONCLUSIONS: The landscape of obesity treatment is changing rapidly. Of the new therapeutic options presented, all options have associated adverse events requiring long-term safety data, but the availability of new options is a welcome development.

Epigenetic regulation of miRNA-124 and multiple downstream targets is associated with treatment response in myeloid malignancies.

Epigenetic regulation of microRNA (miRNA) expression has recently been implicated in the pathogenesis of myelodysplastic syndrome (MDS). Particular interest has focused on miRNA-124 expression, which is inhibited in MDS and has recently been demonstrated to be upregulated in response to epigenetic treatment (EGT). Previous studies have determined the in vitro and in vivo expression of miRNA-124 and several molecular targets, including cyclin-dependent kinase (CDK) 4, CDK6 and enhancer of zeste homolog 2 (EZH2), in order to elucidate the molecular mechanisms associated with the miRNA-124-mediated therapeutic response to EGT in MDS and identify additional potential biomarkers of early EGT treatment response in myeloid malignancies. In vitro studies in the HL60 leukemic cell line identified upregulation of miRNA-124 expression in response to single-agent EGT with either azacytidine (AZA) or the histone deacetylase inhibitor panobinostat (LBH589). Combination EGT with AZA and LBH589 resulted in significant additive induction of miRNA-124 expression. Expression of downstream targets of miRNA-124, including CDK4, CDK6 and EZH2, in response to single agent and combined EGT was determined in HL60 cells. Single and combination EGT treatment resulted in inhibition of CDK4, CDK6 and EZH2 expression with combination EGT resulting in a significant and additive inhibitory effect. In vivo studies using peripheral blood mononuclear cells from patients receiving combination EGT for high risk MDS or acute myeloid leukemia demonstrated significant induction of miRNA-124 and inhibition CDK4 and CDK6 messenger (m)RNA expression in patients that responded to combination EGT. A trend to inhibited EZH2 mRNA expression was also identified in response to combination EGT. Overall, the present observations identify a potential molecular mechanism for miRNA-124-mediated response to EGT involving regulation of CDK4, CDK6 and EZH2 expression. In addition, the present findings further qualify miRNA-124 as a possible biomarker of early response to EGT in myeloid malignancies and potentially a valid therapeutic target, together with CDK4, CDK6 and EZH2.

Molecular and cellular mechanisms of glucagon-like peptide-1 receptor agonist-mediated attenuation of cardiac fibrosis.

BACKGROUND: Glucagon-like peptide-1 receptor agonists may have a role in modulation of cardiac fibrosis. Our study aimed to determine the effect of the glucagon-like peptide-1 receptor agonist liraglutide in obesity, hypertension and age-induced murine models of cardiac fibrosis and identify associated molecular mechanisms. METHODS: C57Bl/6J mice on a high-fat diet and C57Bl/6J mice on a normal chow diet treated with angiotensin II were used to induce obesity and hypertension-mediated cardiac fibrosis, respectively. C57Bl/6J mice 20 months old were used to study age-induced cardiac fibrosis. Liraglutide treatment of 30 µg/kg/day-300 µg/kg s.c. twice daily was administered for 4 weeks. RESULTS: Liraglutide treatment attenuated obesity, hypertension and age-induced increases in interstitial cardiac fibrosis and expression of inflammatory and oxidative stress markers. CONCLUSIONS: These observations identify a potential role for liraglutide in the prevention of cardiac fibrosis and identify molecular mechanisms associated with these effects.

TElmisartan in the management of abDominal aortic aneurYsm (TEDY): The study protocol for a randomized controlled trial.

BACKGROUND: Experimental studies suggest that angiotensin II plays a central role in the pathogenesis of abdominal aortic aneurysm. This trial aims to evaluate the efficacy of the angiotensin receptor blocker telmisartan in limiting the progression of abdominal aortic aneurysm. METHODS/DESIGN: Telmisartan in the management of abdominal aortic aneurysm (TEDY) is a multicentre, parallel-design, randomised, double-blind, placebo-controlled trial with an intention-to-treat analysis. We aim to randomly assign 300 participants with small abdominal aortic aneurysm to either 40 mg of telmisartan or identical placebo and follow patients over 2 years. The primary endpoint will be abdominal aortic aneurysm growth as measured by 1) maximum infra-renal aortic volume on computed tomographic angiography, 2) maximum orthogonal diameter on computed tomographic angiography, and 3) maximum diameter on ultrasound. Secondary endpoints include change in resting brachial blood pressure, abdominal aortic aneurysm biomarker profile and health-related quality of life. TEDY is an international collaboration conducted from major vascular centres in Australia, the United States and the Netherlands. DISCUSSION: Currently, no medication has been convincingly demonstrated to limit abdominal aortic aneurysm progression. TEDY will examine the potential of a promising treatment strategy for patients with small abdominal aortic aneurysms. TRIAL REGISTRATION: Australian and Leiden study centres: Australian New Zealand Clinical Trials Registry ACTRN12611000931976 , registered on 30 August 2011; Stanford study centre: clinicaltrials.gov NCT01683084 , registered on 5 September 2012.

Entinostat is a histone deacetylase inhibitor selective for class 1 histone deacetylases and activates HIV production from latently infected primary T cells.

OBJECTIVES: To compare the potency, toxicity and mechanism of action of multiple histone deacetylase inhibitors (HDACi) in activating HIV production from latency. DESIGN: In-vitro analysis of HDACi in a primary T-cell model of HIV latency and latently infected cell lines. METHODS: Latently infected chemokine ligand 19 (CCL19)-treated CD4⁺ T cells and the latently infected cell lines ACH2 and J-Lat were treated with a panel of HDACi, including entinostat, vorinostat, panonbinostat and MCT3. Viral production and cell viability were compared. Expression of cellular HDACs was measured by western blot and PCR. Association of HDACs with the HIV long-terminal repeat (LTR) using latently infected CCL19-treated primary CD4⁺ T cells in the presence and absence of specific HDACi was determined by chromatin immunoprecipitation (ChIP). RESULTS: We demonstrated considerable variation in the potency and toxicity of HDACi in latently infected primary CD4⁺ T cells and cell lines. All HDACi tested activated HIV production in latently infected primary T cells with greatest potency demonstrated with entinostat and vorinostat and greatest toxicity with panobinostat. Following the addition of HDACi in vitro, there were no changes in markers of T-cell activation or expression of the HIV coreceptors chemokine (C-X-C motif) receptor 4 (CXCR4) or chemokine (C-C motif) receptor type 5 (CCR5). ChIP analysis of latently infected CCL19-treated primary CD4⁺ T cells showed binding by HDAC1, HDAC2 and HDAC3 to the LTR with removal of HDAC1 and HDAC2 following treatment with the HDACi vorinostat and HDAC1 only following treatment with entinostat. CONCLUSION: The HDACi entinostat, selective for inhibition of class I HDACs, induced virus expression in latently infected primary CD4⁺ T cells making this compound an attractive novel option for future clinical trials.

The GLP-1 receptor agonist liraglutide inhibits progression of vascular disease via effects on atherogenesis, plaque stability and endothelial function in an ApoE(-/-) mouse model.

Liraglutide, a once-daily glucagon-like peptide-1 receptor (GLP-1R) agonist, has been approved as a new treatment for type 2 diabetes and is the subject of a clinical trial programme to evaluate the effects on cardiovascular disease and safety. The current study aimed to determine the in vivo effect of liraglutide on progression of atherosclerotic vascular disease in the apolipoprotein E-deficient (ApoE(-/-)) mouse model and identify underlying mechanisms responsible. Liraglutide treatment inhibited progression of early onset, low-burden atherosclerotic disease in a partially GLP-1R-dependent manner in the ApoE(-/-) mouse model. In addition, liraglutide treatment inhibited progression of atherosclerotic plaque formation and enhanced plaque stability, again in a partially GLP-1R-dependent manner. No significant effect of liraglutide on progression of late onset, high-burden atherosclerotic disease was observed. In addition, no significant endothelial cell dysfunction was identified in ApoE(-/-) mice with early onset, low-burden atherosclerotic disease, although significant prevention of weight gain was observed in liraglutide-treated mice using this dietary protocol. Taken together, these results suggest a potential role for liraglutide in the prevention and stabilisation of atherosclerotic vascular disease together with possible protection against major cardiovascular events.

The potential role of homocysteine mediated DNA methylation and associated epigenetic changes in abdominal aortic aneurysm formation.

Previous studies have suggested that homocysteine (Hcy) has wide-ranging biological effects, including accelerating atherosclerosis, impairing post injury endothelial repair and function, deregulating lipid metabolism and inducing thrombosis. However, the biochemical basis by which hyperhomocysteinemia (HHcy) contributes to cardiovascular diseases (CVDs) remains largely unknown. Several case-control studies have reported an association between HHcy and the presence of abdominal aortic aneurysms (AAA) and there are supportive data from animal models. Genotypic data concerning the association between variants of genes involved in the methionine cycle and AAA are conflicting probably due to problems such as reverse causality and confounding. The multifactorial nature of AAA suggests the involvement of additional epigenetic factors in disease formation. Elevated Hcy levels have been previously linked to altered DNA methylation levels in various diseases. Folate or vitamin B12 based methods of lowering Hcy have had disappointingly limited effects in reducing CVD events. One possible reason for the limited efficacy of such therapy is that they have failed to reverse epigenetic changes induced by HHcy. It is possible that individuals with HHcy have an "Hcy memory effect" due to epigenetic alterations which continue to promote progression of cardiovascular complications even after Hcy levels are lowered. It is possible that deleterious effect of prior, extended exposure to elevated Hcy concentrations have long-lasting effects on target organs and genes, hence underestimating the benefit of Hcy lowering therapies in CVD patients. Therapies targeting the epigenetic machinery as well as lowering circulating Hcy concentrations may have a more efficacious effect in reducing the incidence of cardiovascular complications.