The Role of miR-181c in Mechanisms of Diabetes-Impaired Angiogenesis: An Emerging Therapeutic Target for Diabetic Vascular Complications

Diabetes mellitus is estimated to affect up to 700 million people by the year 2045, contributing to an immense health and economic burden. People living with diabetes have a higher risk of developing numerous debilitating vascular complications, leading to an increased need for medical care, a reduced quality of life and increased risk of early death. Current treatments are not satisfactory for many patients who suffer from impaired angiogenesis in response to ischaemia, increasing their risk of ischaemic cardiovascular conditions. These vascular pathologies are characterised by endothelial dysfunction and abnormal angiogenesis, amongst a host of impaired signaling pathways. Therapeutic stimulation of angiogenesis holds promise for the treatment of diabetic vascular complications that stem from impaired ischaemic responses. However, despite significant effort and research, there are no established therapies that directly stimulate angiogenesis to improve ischaemic complications such as ischaemic heart disease and peripheral artery disease, highlighting the immense unmet need. However, despite significant effort and research, there are no established therapies that directly stimulate angiogenesis in a clinical setting, highlighting the immense unmet need. MicroRNAs (miRNAs) are emerging as powerful targets for multifaceted diseases including diabetes and cardiovascular disease. This review highlights the potential role of microRNAs as therapeutic targets for rescuing diabetes-impaired angiogenesis, with a specific focus on miR-181c, which we have previously identified as an important angiogenic regulator. Here we summarise the pathways currently known to be regulated by miR-181c, which include the classical angiogenesis pathways that are dysregulated in diabetes, mitochondrial function and axonal guidance, and describe how these relate both directly and indirectly to angiogenesis. The pleiotropic actions of miR-181c across multiple key angiogenic signaling pathways and critical cellular processes highlight its therapeutic potential as a novel target for treating diabetic vascular complications.Emma L. Solly, Peter J. Psaltis, Christina A. Bursill, and Joanne T. M. Ta

On the nonlinear relationship between wall shear stress topology and multi-directionality in coronary atherosclerosis

Background and Objective: In this paper we investigate twelve multi-directional/topological wall shear stress (WSS) derived metrics and their relationships with the formation of coronary plaques in both computational fluid dynamics (CFD) and dynamic fluid-structure interaction (FSI) frameworks. While low WSS is one of the most established biomechanical markers associated with coronary atherosclerosis progression, alone it is limited. Multi-directional and topological WSS derived metrics have been shown to be important in atherosclerosis related mechanotransduction and near-wall transport processes. However, the relationships between these twelve WSS metrics and the influence of both FSI simulations and coronary dynamics is understudied. Methods: We first investigate the relationships between these twelve WSS derived metrics, stenosis percentage and lesion length through a parametric, transient CFD study. Secondly, we extend the parametric study to FSI, both with and without the addition of coronary dynamics, and assess their correlations. Finally, we present the case of a patient who underwent invasive coronary angiography and optical coherence tomography imaging at two time points 18 months apart. Associations between each of the twelve WSS derived metrics in CFD, static FSI and dynamic FSI simulations were assessed against areas of positive/negative vessel remodelling, and changes in plaque morphology. Results: 22–32% stenosis was the threshold beyond which adverse multi-directional/topological WSS results. Each metric produced a different relationship with changing stenoses and lesion length. Transient haemodynamics was impacted by coronary dynamics, with the topological shear variation index suppressed by up to 94%. These changes appear more critical at smaller stenosis levels, suggesting coronary dynamics could play a role in the earlier stages of atherosclerosis development. In the patient case, both dynamics and FSI vs CFD changes altered associations with measured changes in plaque morphology. An appendix of the linear fits between the various FSI- and CFD-based simulations is provided to assist in scaling CFD-based results to resemble the compliant walled characteristics of FSI more accurately. Conclusions: These results highlight the potential for coronary dynamics to alter multidirectional/topological WSS metrics which could impact associations with changes in coronary atherosclerosis over time. These results warrant further investigation in a wider range of morphological settings and longitudinal cohort studies in the future.Harry J. Carpenter, Mergen H. Ghayesha, Anthony C. Zander, Peter J. Psalti

MAPK-interacting kinase 2 (MNK2) regulates adipocyte metabolism independently of its catalytic activity

The mitogen-activated protein kinase (MAPK)-interacting kinases (MNKs) are serine/threonine protein kinases that are activated by the ERK1/2 (extracellular-regulated kinase) and p38α/β MAPK pathways. The MNKs have previously been implicated in metabolic disease and shown to mediate diet-induced obesity. In particular, knockout of MNK2 in mice protects from the weight gain induced by a high-fat diet. These and other data suggest that MNK2 regulates expansion of adipose tissue, a stable, long-term energy reserve that plays an important role in regulating whole-body energy homeostasis. Using the well-established mouse 3T3-L1 in vitro model of adipogenesis, the role of the MNKs in adipocyte differentiation and lipid storage was investigated. Inhibition of MNK activity using specific inhibitors failed to impair adipogenesis or lipid accumulation, suggesting that MNK activity is not required for adipocyte differentiation and does not regulate lipid storage. However, small-interfering RNA (siRNA) knockdown of MNK2 did reduce lipid accumulation and regulated the levels of two major lipogenic transcriptional regulators, ChREBP (carbohydrate response-element binding protein) and LPIN1 (Lipin-1). These factors are responsible for controlling expression of genes for proteins involved in de novo lipogenesis and triglyceride synthesis. Knockdown of MNK2 also increased the expression of hormone-sensitive lipase which catalyses the breakdown of triglyceride. These findings identify MNK2 as a regulator of adipocyte metabolism, independently of its catalytic activity, and reveal some of the mechanisms by which MNK2 drives adipose tissue expansion. The development of an MNK2-targeted therapy may therefore be a useful intervention for reducing weight caused by excessive nutrient intake.James E. Merrett, Jianling Xie, Peter J. Psaltis, and Christopher G. Prou

Management of multivessel coronary artery disease in patients with non-ST-elevation myocardial infarction: a complex path to precision medicine

Recent analyses suggest the incidence of acute coronary syndrome is declining in high- and middle-income countries. Despite this, overall rates of non-ST-elevation myocardial infarction (NSTEMI) continue to rise. Furthermore, NSTEMI is a greater contributor to mortality after hospital discharge than ST-elevation myocardial infarction (STEMI). Patients with NSTEMI are often older, comorbid and have a high likelihood of multivessel coronary artery disease (MVD), which is associated with worse clinical outcomes. Currently, optimal treatment strategies for MVD in NSTEMI are less well established than for STEMI or stable coronary artery disease. Specifically, in relation to percutaneous coronary intervention (PCI) there is a paucity of randomized, prospective data comparing multivessel and culprit lesion-only PCI. Given the heterogeneous pathological basis for NSTEMI with MVD, an approach of complete revascularization may not be appropriate or necessary in all patients. Recognizing this, this review summarizes the limited evidence base for the interventional management of non-culprit disease in NSTEMI by comparing culprit-only and multivessel PCI strategies. We then explore how a personalized, precise approach to investigation, therapy and follow up may be achieved based on patient-, disease- and lesion-specific factors.Angus A.W. Baumann, Aashka Mishra, Matthew I. Worthley, Adam J. Nelson and Peter J. Psalti

The role of intracoronary imaging in translational research

Abstract: Atherosclerotic cardiovascular disease is a key public health concern worldwide and leading cause of morbidity, mortality and health economic costs. Understanding atherosclerotic plaque microstructure in relation to molecular mechanisms that underpin its initiation and progression is needed to provide the best chance of combating this disease. Evolving vessel wall-based, endovascular coronary imaging modalities, including intravascular ultrasound (IVUS), optical coherence tomography (OCT) and near-infrared spectroscopy (NIRS), used in isolation or as hybrid modalities, have been advanced to allow comprehensive visualization of the pathological substrate of coronary atherosclerosis and accurately measure temporal changes in both the vessel wall and plaque characteristics. This has helped further our appreciation of the natural history of coronary artery disease (CAD) and the risk for major adverse cardiovascular events (MACE), evaluate the responsiveness to conventional and experimental therapeutic interventions, and assist in guiding percutaneous coronary intervention (PCI). Here we review the use of different imaging modalities for these purposes and the lessons they have provided thus far.Nicholas J. Montarello, Adam J. Nelson, Johan Verjans, Stephen J. Nicholls, Peter J. Psalti

Acute ST-segment myocardial infarction-evolution of treatment strategies

The commonest cause of acute myocardial infarction involves the rupture or erosion of vulnerable athero- sclerotic plaques followed by aggregation of platelets and subsequent thrombus formation, leading to par- tial or complete epicardial coronary arterial occlusion. Over the last 25 years, advancement in therapeutic options for acute myocardial infarction has resulted in substantial improvement in morbidity and mortal- ity. As a result, the absolute risk reduction of in-hos- pital deaths for patients presenting with STEMI has been on the decline in the last decade. The focus of the treatment for acute myocardial infarction invol- ves achieving epicardial and microvascular patency, prevention of recurrent ischaemic events while bal- ancing the risk of bleeding. This involves antiplatelet and antithrombotic therapies or fibrinolytic agents when timely performance of primary percutaneous coronary intervention is not possible. We review the evolution of treatment strategies for STEMI that has contributed to the improvement in patient outcome.Dennis T. L. Wong, Rishi Puri, Peter J. Psaltis, Stephen G. Worthley, Matthew I. Worthle

MicroRNAs as therapeutic targets and clinical biomarkers in atherosclerosis

Atherosclerotic cardiovascular disease remains the leading cause of morbidity and mortality worldwide. Atherosclerosis develops over several decades and is mediated by a complex interplay of cellular mechanisms that drive a chronic inflammatory milieu and cell-to-cell interactions between endothelial cells, smooth muscle cells and macrophages that promote plaque development and progression. While there has been significant therapeutic advancement, there remains a gap where novel therapeutic approaches can complement current therapies to provide a holistic approach for treating atherosclerosis to orchestrate the regulation of complex signalling networks across multiple cell types and different stages of disease progression. MicroRNAs (miRNAs) are emerging as important post-transcriptional regulators of a suite of molecular signalling pathways and pathophysiological cellular effects. Furthermore, circulating miRNAs have emerged as a new class of disease biomarkers to better inform clinical diagnosis and provide new avenues for personalised therapies. This review focusses on recent insights into the potential role of miRNAs both as therapeutic targets in the regulation of the most influential processes that govern atherosclerosis and as clinical biomarkers that may be reflective of disease severity, highlighting the potential theranostic (therapeutic and diagnostic) properties of miRNAs in the management of cardiovascular disease.Emma L. Solly, Catherine G. Dimasi, Christina A. Bursill, Peter J. Psaltis, and Joanne T.M. Ta

Inflammation as a therapeutic target in atherosclerosis

Atherosclerotic coronary artery disease (CAD) results from build-up of cholesterol-rich plaques in the walls of the coronary arteries and is a leading cause of death. Inflammation is central to atherosclerosis. Uncontrolled inflammation makes coronary plaques "unstable" and vulnerable to rupture or erosion, leading to thrombosis and myocardial infarction (MI). As multiple inflamed plaques often co-exist in the coronary system, patients are at risk of repeated atherothrombotic cardiovascular events after MI, with rates of 10-12% at one year and 18-20% at three years. This is largely because current therapies for CAD, such as lipid-lowering statins, do not adequately control plaque inflammation. New anti-atherosclerotic agents are therefore needed, especially those that better target inflammation. The recent positive results for the anti-interleukin-1-beta (IL-1β) monoclonal antibody, Canakinumab, in the Canakinumab Anti-inflammatory Thrombosis Outcome Study (CANTOS) clinical trial has provided a major stimulant to the field. It highlights that not only is inflammation important from a pathogenic and risk prediction perspective in CAD, but that reducing inflammation can be beneficial. The challenge is now to find the best strategies to achieve this in real-world practice. This review outlines the role that inflammation plays in atherosclerosis and provides an update on anti-inflammatory therapies currently being investigated to target atherosclerosis.Mau T Nguyen, Sanuja Fernando, Nisha Schwarz, Joanne TM Tan, Christina A Bursill and Peter J Psalti

DelIrium VULnerability in GEriatrics (DIVULGE) study: A protocol for a prospective observational study of electroencephalogram associations with incident postoperative delirium

Delirium is a neurocognitive disorder common in older adults in acute care settings. Those who develop delirium are at an increased risk of dementia, cognitive decline and death. Electroencephalography (EEG) during delirium in older adults is characterised by slowing and reduced functional connectivity, but markers of vulnerability are poorly described. We aim to identify EEG spectral power and event-related potential (ERP) markers of incident delirium in older adults to understand neural mechanisms of delirium vulnerability. Characterising delirium vulnerability will provide substantial theoretical advances and outcomes have the potential to be translated into delirium risk assessment tools.Monique S Boord, Daniel H J Davis, Peter J Psaltis, Scott W Coussens, Daniel Feuerriegel, Marta I Garrido, Alice Bourke, Hannah A D Keag

Risk factors for delirium and cognitive decline following coronary artery bypass grafting surgery: a systematic review and meta-analysis

Background: Coronary artery bypass grafting (CABG) is known to improve heart function and quality of life, while rates of surgery-related mortality are low. However, delirium and cognitive decline are common complications. We sought to identify preoperative, intraoperative, and postoperative risk or protective factors associated with delirium and cognitive decline (across time) in patients undergoing CABG. Methods and Results: We conducted a systematic search of Medline, PsycINFO, EMBASE, and Cochrane (March 26, 2019) for peer-reviewed, English publications reporting post-CABG delirium or cognitive decline data, for at least one risk factor. Random-effects meta-analyses estimated pooled odds ratio for categorical data and mean difference or standardized mean difference for continuous data. Ninety-seven studies, comprising data from 60 479 patients who underwent CABG, were included. Moderate to large and statistically significant risk factors for delirium were as follows: (1) preoperative cognitive impairment, depression, stroke history, and higher European System for Cardiac Operative Risk Evaluation (EuroSCORE) score, (2) intraoperative increase in intubation time, and (3) postoperative presence of arrythmia and increased days in the intensive care unit; higher preoperative cognitive performance was protective for delirium. Moderate to large and statistically significant risk factors for acute cognitive decline were as follows: (1) preoperative depression and older age, (2) intraoperative increase in intubation time, and (3) postoperative presence of delirium and increased days in the intensive care unit. Presence of depression preoperatively was a moderate risk factor for midterm (1–6 months) post-CABG cognitive decline. Conclusions: This meta-analysis identified several key risk factors for delirium and cognitive decline following CABG, most of which are nonmodifiable. Future research should target preoperative risk factors, such as depression or cognitive impairment, which are potentially modifiable.Danielle Greaves, Peter J. Psaltis, Daniel H.J. Davis, Tyler J. Ross, Erica S. Ghezzi, Amit Lampit, Ashleigh E. Smith, Hannah A.D. Keag