The cardiac fetal gene program in heart failure:From OPLAH to 5-oxoproline and beyond

Chronisch hartfalen is één van de belangrijkste problemen in de huidige gezondheidszorg. Patiënten met hartfalen hebben een hoog risico om te komen overlijden. De 5-jaars overleving van patiënten met hartfalen is minder dan 50%. Helaas is genezing vaak niet mogelijk. Deze slechte prognose geldt voor zowel mannen als vrouwen. Ondanks de vele doorbraken zijn de onderliggende mechanismen voor de ontwikkeling en progressie van hartfalen tot op heden nog onvoldoende opgehelderd. In recente jaren is gebleken dat cardiale schade leidt tot het omschakelen van een volwassen genprofiel naar een genprofiel dat kenmerkend is voor een foetaal hart. In mijn proefschrift toon ik aan dat nieuwe behandelstrategieën mogelijk door van het karakteriseren van deze zogeheten foetale herprogrammering. We hebben OPLAH geïdentificeerd als nieuw cardiaal foetaal gen, hetgeen een beschermende rol speelt in het hart en beschermt tegen hartfalen. Bovendien hebben we 5-oxoproline geïdentificeerd als nieuwe biomarker voor hartfalen. Samengevat hebben we OPLAH/5-oxoproline-as geïdentificeerd als een nieuw ziekteproces binnen de pathofysiologie van hartfalen. Deze as zou een mogelijk nieuw target voor behandeling kunnen zijn in patiënten met hartfalen.Heart failure as a result of myocardial infarction and ischaemic heart disease remains the most prominent health challenge of the developed world, with a five year survival rate of less than 50%. Although, many breakthroughs have been made, the fundamental mechanisms responsible for the development and progression of heart failure have not yet been fully elucidated. In recent years it has been observed that cardiac injury in the adult heart leads to a switch in gene expression which to some extend resembles the expression pattern observed in the fetal heart, a process dubbed cardiac fetal reprogramming. With this thesis we tried to further characterize cardiac fetal reprogramming in heart failure, and how a better understanding of this process can lead to novel therapeutic strategies for patients. We identified OPLAH as a novel cardiac fetal gene, which has encodes for an enzyme that has a cardio-protective effect in heart failure. Additionally we demonstrated that 5-oxoproline, substrate of OPLAH, levels are elevated in plasma of heart failure patients, suggesting this metabolite to be a novel putative biomarker in patients with heart failure. Together these findings identify OPLAH and 5-oxoproline as a novel pathophysiological pathway in heart failure, and targeting the expression and/or activity of OPLAH may lead to new therapeutic options of heart failure patients

Hydrogels for Cardiac Restorative Support:Relevance of Gelation Mechanisms for Prospective Clinical Use

Purpose of Review: Cardiac tissue regenerative strategies have gained much traction over the years, in particular those utilizing hydrogels. With our review, and with special focus on supporting post-myocardial infarcted tissue, we aim to provide insights in determining crucial design considerations of a hydrogel and the implications these could have for future clinical use. Recent Findings: To date, two hydrogel delivery strategies are being explored, cardiac injection or patch, to treat myocardial infarction. Recent advances have demonstrated that the mechanism by which a hydrogel is gelated (i.e., physically or chemically cross-linked) not only impacts the biocompatibility, mechanical properties, and chemical structure, but also the route of delivery of the hydrogel and thus its effect on cardiac repair. Summary: With regard to cardiac regeneration, various hydrogels have been developed with the ability to function as a delivery system for therapeutic strategies (e.g., drug and stem cells treatments), as well as a scaffold to guide cardiac tissue regeneration following myocardial infarction. However, these developments remain within the experimental and pre-clinical realm and have yet to transition towards the clinical setting.</p

The Development and Subsequent Elimination of Aberrant Peripheral Axon Projections in Semaphorin3A Null Mutant Mice

AbstractSemaphorin3A (previously known as Semaphorin III, Semaphorin D, or collapsin-1) is a member of the semaphorin gene family, many of which have been shown to guide axons during nervous system development. Semaphorin3A has been demonstrated to be a diffusible chemorepulsive molecule for axons of selected neuronal populations in vitro. Analysis of embryogenesis in two independent lines of Semaphorin3A knockout mice support the hypothesis that this molecule is an important guidance signal for neurons of the peripheral nervous system (M. Taniguchi et al., 1997, Neuron 19, 519–530; E. Ulupinar et al., 1999, Mol. Cell. Neurosci. 13, 281–292). Surprisingly, newborn Semaphorin3A null mutant mice exhibit no significant abnormalities (O. Behar et al., 1996, Nature 383, 525–528). In this study we have tested the hypothesis that guidance abnormalities that occurred during early stages of Semaphorin3A null mice development are corrected later in development. We have found that the extensive abnormalities formed during early developmental stages in the peripheral nervous system are largely eliminated by embryonic day 15.5. We demonstrate further that at least in one distinct anatomical location these abnormalities are mainly the result of aberrant projections. In conclusion, these findings suggest the existence of correction mechanisms that eliminate most sensory axon pathfinding errors early in development

OPLAH ablation leads to accumulation of 5-oxoproline, oxidative stress, fibrosis, and elevated fillings pressures:a murine model for heart failure with a preserved ejection fraction

Aims The prevalence of heart failure with a preserved ejection fraction (HFpEF) is increasing, but therapeutic options are limited. Oxidative stress is suggested to play an important role in the pathophysiology of HFpEF. However, whether oxidative stress is a bystander due to comorbidities or causative in itself remains unknown. Recent results have shown that depletion of 5-oxoprolinase (OPLAH) leads to 5-oxoproline accumulation, which is an important mediator of oxidative stress in the heart. We hypothesize that oxidative stress induced by elevated levels of 5-oxoproline leads to the onset of a murine HFpEF-like phenotype. Methods and results Oplah full body knock-out (KO) mice had higher 5-oxoproline levels coupled to increased oxidative stress. Compared with wild-type (WT) littermates, KO mice had increased cardiac and renal fibrosis with concurrent elevated left ventricular (LV) filling pressures, impaired LV relaxation, yet a normal LV ejection fraction. Following the induction of cardiac ischaemia/reperfusion (IR) injury, 52.4% of the KO mice died compared with only 15.4% of the WT mice (P <0.03). Furthermore, KO mice showed a significantly increased atrial, ventricular, kidney, and liver weights compared with WT mice (P <0.05 for all). Cardiac and renal fibrosis were more pronounced following cardiac IR injury in the KO mice and these mice developed proteinuria post-IR injury. To further address the link between 5-oxoproline and HFpEF, 5-oxoproline was measured in the plasma of HFpEF patients. Compared with healthy controls (3.8 +/- 0.6 mu M), 5-oxoproline levels were significantly elevated in HFpEF patients (6.8 +/- 1.9 mu M, P <0.0001). Furthermore, levels of 5-oxoproline were independently associated with more concentric remodelling on echocardiography. Conclusion Oxidative stress induced by 5-oxoproline results in a murine phenotype reminiscent of the clinical manifestation of HFpEF without the need for surgical or pharmacological interference. Better understanding of the role of oxidative stress in HFpEF may potentially lead to novel therapeutic options

The cardiac fetal gene program in heart failure: From OPLAH to 5-oxoproline and beyond

Chronisch hartfalen is één van de belangrijkste problemen in de huidige gezondheidszorg. Patiënten met hartfalen hebben een hoog risico om te komen overlijden. De 5-jaars overleving van patiënten met hartfalen is minder dan 50%. Helaas is genezing vaak niet mogelijk. Deze slechte prognose geldt voor zowel mannen als vrouwen. Ondanks de vele doorbraken zijn de onderliggende mechanismen voor de ontwikkeling en progressie van hartfalen tot op heden nog onvoldoende opgehelderd. In recente jaren is gebleken dat cardiale schade leidt tot het omschakelen van een volwassen genprofiel naar een genprofiel dat kenmerkend is voor een foetaal hart. In mijn proefschrift toon ik aan dat nieuwe behandelstrategieën mogelijk door van het karakteriseren van deze zogeheten foetale herprogrammering. We hebben OPLAH geïdentificeerd als nieuw cardiaal foetaal gen, hetgeen een beschermende rol speelt in het hart en beschermt tegen hartfalen. Bovendien hebben we 5-oxoproline geïdentificeerd als nieuwe biomarker voor hartfalen. Samengevat hebben we OPLAH/5-oxoproline-as geïdentificeerd als een nieuw ziekteproces binnen de pathofysiologie van hartfalen. Deze as zou een mogelijk nieuw target voor behandeling kunnen zijn in patiënten met hartfalen

A Brief History in Cardiac Regeneration, and How the Extra Cellular Matrix May Turn the Tide

Tissue homeostasis is perturbed by stressful events, which can lead to organ dysfunction and failure. This is particularly true for the heart, where injury resulting from myocardial infarction or ischemic heart disease can result in a cascading event ultimately ending with the loss of functional myocardial tissue and heart failure. To help reverse this loss of healthy contractile tissue, researchers have spent decades in the hopes of characterizing a cell source capable of regenerating the injured heart. Unfortunately, these strategies have proven to be ineffective. With the goal of truly understanding cardiac regeneration, researchers have focused on the innate regenerative abilities of zebrafish and neonatal mammals. This has led to the realization that although cells play an important role in the repair of the diseased myocardium, inducing cardiac regeneration may instead lie in the composition of the extra cellular milieu, specifically the extra cellular matrix. In this review we will briefly summarize the current knowledge regarding cell sources used for cardiac regenerative approaches, since these have been extensively reviewed elsewhere. More importantly, by revisiting innate cardiac regeneration observed in zebrafish and neonatal mammals, we will stress the importance the extra cellular matrix has on reactivating this potential in the adult myocardium. Finally, we will address how we can harness the ability of the extra cellular matrix to guide cardiac repair thereby setting the stage of next generation regenerative strategies

LC-MS analysis of key components of the glutathione cycle in tissues and body fluids from mice with myocardial infarction

Oxidative stress is suggested to play an important role in several pathophysiological conditions. A recent study showed that decreasing 5-oxoproline (pyroglutamate) concentration, an important mediator of oxidative stress, by over-expressing 5-oxoprolinase, improves cardiac function post-myocardial infarction in mice. The aim of the current study is to gain a better understanding of the role of the glutathione cycle in a mouse model of myocardial infarction by establishing quantitative relationships between key components of this cycle. We developed and validated an LC-MS method to quantify 5-oxoproline, L-glutamate, reduced glutathione (GSH) and oxidized GSH (GSSG) in different biological samples (heart, kidney, liver, plasma, and urine) of mice with and without myocardial infarction. 5-oxoproline concentration was elevated in all biological samples from mice with myocardial infarction. The ratio of GSH/GSSG was significantly decreased in cardiac tissue, but not in the other tissues/body fluids. This emphasizes the role of 5-oxoproline as an inducer of oxidative stress related to myocardial infarction and as a possible biomarker. An increase in the level of 5-oxoproline is associated with a decrease in the GSH/GSSG ratio, a well-established marker for oxidative stress, in cardiac tissue post-myocardial infarction. This suggests that 5-oxoproline may serve as an easily measurable marker for oxidative stress resulting from cardiac injury. Our findings show further that liver and kidneys have more capacity to cope with oxidative stress conditions in comparison to the heart, since the GSH/GSSG ratio is not affected in these organs despite a significant increase in 5-oxoproline. (C) 2018 Elsevier B.V. All rights reserved

In Vitro Methods To Model Cardiac Mechanobiology In Health And Disease

In vitro cardiac modeling has taken great strides in the past decade. While most cell and engineered tissue models have focused on cell and tissue contractile function as readouts, mechanobiological cues from the cell environment that affect this function, such as matrix stiffness or organization, are less well explored. In this study, we review two-dimensional (2D) and three-dimensional (3D) models of cardiac function that allow for systematic manipulation or precise control of mechanobiological cues under simulated (patho)physiological conditions while acquiring multiple readouts of cell and tissue function. We summarize the cell types used in these models and highlight the importance of linking 2D and 3D models to address the multiscale organization and mechanical behavior. Finally, we provide directions on how to advance in vitro modeling for cardiac mechanobiology using next generation hydrogels that mimic mechanical and structural environmental features at different length scales and diseased cell types, along with the development of new tissue fabrication and readout techniques. Impact statement Understanding the impact of mechanobiology in cardiac (patho)physiology is essential for developing effective tissue regeneration and drug discovery strategies and requires detailed cause-effect studies. The development of three-dimensional in vitro models allows for such studies with high experimental control, while integrating knowledge from complementary cell culture models and in vivo studies for this purpose. Complemented by the use of human-induced pluripotent stem cells, with or without predisposed genetic diseases, these in vitro models will offer promising outlooks to delineate the impact of mechanobiological cues on human cardiac (patho)physiology in a dish