A Review of the Molecular Mechanisms Underlying the Development and Progression of Cardiac Remodeling. Oxid Med Cell Longev. 2017;2017:3920195. [PMID: 28751931 PMCID: PMC5511646 DOI: 10.1155/2017/3920195]

Dual Role of Triptolide in Interrupting the NLRP3 Inflammasome Pathway to Attenuate Cardiac Fibrosis

In a previous paper, we reported that triptolide (TP), a commonly used immunomodulator, could attenuate cardiac hypertrophy. This present study aimed to further explore the inhibition of cardiac fibrosis by TP and the possible mechanism from the perspective of the NOD-like receptor protein 3 (NLRP3) inflammasome. Hematoxylin-eosin and Masson’s staining, immunohistochemistry, and immunofluorescence were performed to observe cardiac fibrotic changes in mice and mouse cardiac fibroblasts (CFs). The Western blot, colocalization, and immunoprecipitation were applied to detect protein expression and interactions. Results suggested that TP dose-dependently inhibited cardiac fibrosis induced by isoproterenol and collagen production of CFs induced by angiotensin II. TP exhibited an antifibrotic effect via inhibiting activation of the NLRP3 inflammasome, which sequentially decreased IL-1β maturation, myeloid differentiation factor 88 (MyD88)-related phosphorylation of c-Jun N-terminal kinase (JNK), extracellular regulated protein kinase 1/2 (ERK1/2), and TGF-β1/Smad signaling, and ultimately resulted in less collagen production. Moreover, TP showed no antifibrotic effect in Nlrp3-knockout CFs. Notably, TP inhibited the expression of NLRP3 and apoptosis-associated speck-like proteins containing a caspase recruitment domain (ASC) as well as inflammasome assembly, by interrupting the NLRP3-ASC interaction to inhibit inflammasome activation. Finally, TP indeed inhibited the NLRP3-TGFβ1-Smad pathway in vivo. Conclusively, TP was found to play a dual role in interrupting the activation of the NLRP3 inflammasome to attenuate cardiac fibrosis.

mTOR and Beclin1: Two key autophagy-related molecules and their roles in myocardial ischemia/reperfusion injury

Autophagy is the general term of lysosomal degradation of substances in cells, which is considered the key to maintaining the normal structure and function of the heart. It also has a correlation with several heart diseases, in particular, myocardial ischemia/reperfusion (I/R) injury. At the stage of myocardial ischemia, autophagy degrades nonfunctional cytoplasmic proteins providing the critical nutrients for the critical life activities, thereby suppressing cell apoptosis and necrosis. However, autophagy is likely to affect the heart negatively in the reperfusion stage. Mammalian target of rapamycin (mTOR) and Beclin1 are two vital autophagy-related molecules in myocardial I/R injury playing significant roles in different stages. In the ischemia stage, mTOR plays its roles through AMPK/mTOR and phosphoinositide 3-kinase/Akt/mTOR pathway, whereas Beclin1 plays its roles through its upregulation in the reperfusion stage. A possible interaction between mTOR and Beclin1 has been reported recently, and further studies need to be done to find the underlying interaction between the two molecules in myocardial I/R injury.

Crosstalk between MicroRNAs and Peroxisome Proliferator-Activated Receptors and Their Emerging Regulatory Roles in Cardiovascular Pathophysiology

Peroxisome proliferator-activated receptors (PPARs) play vital roles in cardiovascular pathophysiology, such as energy balance, cell proliferation/apoptosis, inflammatory response, and adipocyte differentiation. These vital roles make PPARs potential targets for therapeutic prevention of cardiovascular diseases (CVDs). Emerging evidence indicates that the crosstalk of microRNAs (miRNAs) and PPARs contributes greatly to CVD pathogenesis. PPARs are inhibited by miRNAs at posttranscriptional mechanisms in the progress of pulmonary hypertension and vascular dysfunction involving cell proliferation/apoptosis, communication, and normal function of endothelial cells and vascular smooth muscle cells. In the development of atherosclerosis and stroke, the activation of PPARs could change the transcripts of target miRNA through miRNA signalling. Furthermore, the mutual regulation of PPARs and miRNAs involves cell proliferation/apoptosis, cardiac remodeling, and dysfunction in heart diseases. In addition, obesity, an important cardiovascular risk, is modulated by the regulatory axis of PPARs/miRNAs, including adipogenesis, adipocyte dysfunction, insulin resistance, and macrophage polarization in adipose tissue. In this review, the crosstalk of PPARs and miRNAs and their emerging regulatory roles are summarized in the context of CVDs and risks. This provides an understanding of the underlying mechanism of the biological process related to CVD pathophysiology involving the interaction of PPARs and miRNAs and will lead to the development of PPARs/miRNAs as effective anti-CVD medications.

Nanoparticles for postinfarct ventricular remodeling

In recent years, tremendous progress has been made in the treatment of acute myocardial infarction, but pathological ventricular remodeling often causes survivors to suffer from fatal heart failure. Currently, there is no effective therapy to attenuate ventricular remodeling. Recently, nanoparticle-based drug delivery systems are widely applied in biomedicine especially in cancer and liver fibrosis, owing to its excellent physical, chemical and biological properties. Therefore, the use of nanoparticles as delivery vehicles of small molecules, polypeptides, etc. to improve postinfarct ventricular remodeling is expected. In this review, we summarize the updated researches in this fast-growing area and suggest further works needed.

Possible mechanism for disposal of degenerative cardiomyocytes in human failing hearts: phagocytosis by a neighbour

The index case was a 51‐year‐old woman suffering from doxorubicin cardiomyopathy. In her endomyocardial biopsy specimen, we observed under electron microscopy six scenes in which degenerative cardiomyocytes were engulfed by neighbouring cardiomyocytes. The enclosed cardiomyocytes appeared more degenerative than the enclosing ones in every pair: the myofibrils were more severely damaged. At more degenerative stages, some desmosomes of the intercalated discs on the enclosed cardiomyocyte had disappeared. The membranes between the cardiomyocytes were occasionally disrupted, and there appeared to be sharing of cellular contents between the cells. One pair of such a phagocytosis‐like figure was observed in one case with 5‐fluorouracil cardiomyopathy (a 68‐year‐old man) among eight other chemotherapy‐induced cardiomyopathies but none among 30 non‐drug‐induced dilated cardiomyopathies. The findings suggest a mechanism for disposal of degenerative cardiomyocytes in human failing hearts: phagocytosis by a neighbour, although alternative interpretations remain (e.g. giant autophagic vacuoles or two cardiomyocytes with degenerative intercalated discs).

Stress Coping Strategies in the Heart: An Integrated View

The heart is made up of an ordered amalgam of cardiac cell types that work together to coordinate four major processes, namely energy production, electrical conductance, mechanical work, and tissue remodeling. Over the last decade, a large body of information has been amassed regarding how different cardiac cell types respond to cellular stress that affect the functionality of their elaborate intracellular membrane networks, the cellular reticular network. In the context of the heart, the manifestations of stress coping strategies likely differ depending on the coping strategy outcomes of the different cardiac cell types, and thus may underlie the development of distinct cardiac disorders. It is not clear whether all cardiac cell types have similar sensitivity to cellular stress, how specific coping response strategies modify their unique roles, and how their metabolic status is communicated to other cells within the heart. Here we discuss our understanding of the roles of specialized cardiac cells that together make the heart function as an organ with the ability to pump blood continuously and follow a regular rhythm.

Evaluating the Remote Control of Programmed Cell Death, with or without a Compensatory Cell Proliferation

Organisms and their different component levels, whether organelle, cellular or other, come by birth and go by death, and the deaths are often balanced by new births. Evolution on the one hand has built demise program(s) in cells of organisms but on the other hand has established external controls on the program(s). For instance, evolution has established death program(s) in animal cells so that the cells can, when it is needed, commit apoptosis or senescent death (SD) in physiological situations and stress-induced cell death (SICD) in pathological situations. However, these programmed cell deaths are not predominantly regulated by the cells that do the dying but, instead, are controlled externally and remotely by the cells' superior(s), i.e. their host tissue or organ or even the animal's body. Currently, it is still unclear whether a cell has only one death program or has several programs respectively controlling SD, apoptosis and SICD. In animals, apoptosis exterminates, in a physiological manner, healthy but no-longer needed cells to avoid cell redundancy, whereas suicidal SD and SICD, like homicidal necrosis, terminate ill but useful cells, which may be followed by regeneration of the live cells and by scar formation to heal the damaged organ or tissue. Therefore, “who dies” clearly differentiates apoptosis from SD, SICD and necrosis. In animals, apoptosis can occur only in those cell types that retain a lifelong ability of proliferation and never occurs in those cell types that can no longer replicate in adulthood. In cancer cells, SICD is strengthened, apoptosis is dramatically weakened while SD has been lost. Most published studies professed to be about apoptosis are actually about SICD, which has four basic and well-articulated pathways involving caspases or involving pathological alterations in the mitochondria, endoplasmic reticula, or lysosomes.

TRP channels in cardiac and intestinal fibrosis

It is now widely accepted that advanced fibrosis underlies many chronic inflammatory disorders and is the main cause of morbidity and mortality of the modern world. The pathogenic mechanism of advanced fibrosis involves diverse and intricate interplays between numerous extracellular and intracellular signaling molecules, among which the non-trivial roles of a stress-responsive Ca²⁺/Na⁺-permeable cation channel superfamily, the transient receptor potential (TRP) protein, are receiving growing attention. Available evidence suggests that several TRP channels such as TRPC3, TRPC6, TRPV1, TRPV3, TRPV4, TRPA1, TRPM6 and TRPM7 may play central roles in the progression and/or prevention of fibroproliferative disorders in vital visceral organs such as lung, heart, liver, kidney, and bowel as well as brain, blood vessels and skin, and may contribute to both acute and chronic inflammatory processes involved therein. This short paper overviews the current knowledge accumulated in this rapidly growing field, with particular focus on cardiac and intestinal fibrosis, which are tightly associated with the pathogenesis of atrial fibrillation and inflammatory bowel diseases such as Crohn's disease.

Exploring the cardiac response to injury in heart transplant biopsies

BACKGROUND

Because injury is universal in organ transplantation, heart transplant endomyocardial biopsies present an opportunity to explore response to injury in heart parenchyma. Histology has limited ability to assess injury, potentially confusing it with rejection, whereas molecular changes have potential to distinguish injury from rejection. Building on previous studies of transcripts associated with T cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR), we explored transcripts reflecting injury.

METHODS

Microarray data from 889 prospectively collected endomyocardial biopsies from 454 transplant recipients at 14 centers were subjected to unsupervised principal component analysis and archetypal analysis to detect variation not explained by rejection. The resulting principal component and archetype scores were then examined for their transcript, transcript set, and pathway associations and compared to the histology diagnoses and left ventricular function.

RESULTS

Rejection was reflected by principal components PC1 and PC2, and by archetype scores S2TCMR, and S3ABMR, with S1normal indicating normalness. PC3 and a new archetype score, S4injury, identified unexplained variation correlating with expression of transcripts inducible in injury models, many expressed in macrophages and associated with inflammation in pathway analysis. S4injury scores were high in recent transplants, reflecting donation-implantation injury, and both S4injury and S2TCMR were associated with reduced left ventricular ejection fraction.

CONCLUSION

Assessment of injury is necessary for accurate estimates of rejection and for understanding heart transplant phenotypes. Biopsies with molecular injury but no molecular rejection were often misdiagnosed rejection by histology.TRAIL REGISTRATION. ClinicalTrials.gov NCT02670408FUNDING. Roche Organ Transplant Research Foundation, the University of Alberta Hospital Foundation, and Alberta Health Services.

The long noncoding RNA XIST protects cardiomyocyte hypertrophy by targeting miR-330-3p

Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) are implicated in numerous kinds of cardiovascular diseases, and their vital role in regulating cardiac hypertrophy still needs to be explored. In this study, we demonstrated that lncRNA X-inactive specific transcript (XIST) was upregulated in hypertrophic cardiac of mice and phenylephrine (PE)-treated cardiomyocytes. Next, we observed that inhibition of XIST induced hypertrophic response of cardiomyocyte and overexpression of XIST attenuated cardiomyocyte hypertrophy induced by PE. Furthermore, through online predictive tools and functional experiments, we demonstrated that XIST and S100B were targets of miR-330-3p. XIST and miR-330-3p suppressed each other in a reciprocal way in cardiomyocytes. Additionally, XIST promoted S100B expression through harboring the complementary binding sites with miR-330-3p, eventually prevented cardiac hypertrophy. In conclusion, our findings revealed a novel molecular mechanism that XIST/miR-330-3p/S100B pathway modulates the progression of cardiomyocyte hypertrophy.

The Biological Mechanisms of Action of Cardiac Progenitor Cell Therapy

PURPOSE OF REVIEW

Cell therapy for cardiovascular diseases is regarded as a rapidly growing field within regenerative medicine. Different cellular populations enriched for cardiac progenitor cells (CPCs), or derivate a-cellular products, are currently under preclinical and clinical evaluation. Here, we have reviewed the described mechanisms whereby resident post-natal CPCs, isolated in different ways, act as a therapeutic product on the damaged myocardium.

RECENT FINDINGS

Several biological mechanisms of action have been described which can explain the multiple therapeutic effects of CPC treatment observed on cardiac function and remodelling. These mechanisms span from direct cardiovascular differentiation, through induction of resident progenitor proliferation, to paracrine effects on cardiac and non-cardiac cells mediated by exosomes and non-coding RNAs. All the reported mechanisms of action support an integrated view including cardiomyogenesis, cardioprotection, and anti-fibrotic effects. Moreover, future developments of CPC therapy approaches may support cell-free strategies, exploiting effective pleiotropic cell-derived products, such as exosomes.

The extracellular matrix proteoglycan fibromodulin is upregulated in clinical and experimental heart failure and affects cardiac remodeling

Pressure overload of the heart leads to cardiac remodeling that may progress into heart failure, a common, morbid and mortal condition. Increased mechanistic insight into remodeling is instrumental for development of novel heart failure treatment. Cardiac remodeling comprises cardiomyocyte hypertrophic growth, extracellular matrix alterations including fibrosis, and inflammation. Fibromodulin is a small leucine-rich proteoglycan that regulates collagen fibrillogenesis. Fibromodulin is expressed in the cardiac extracellular matrix, however its role in the heart remains largely unknown. We investigated fibromodulin levels in myocardial biopsies from heart failure patients and mice, subjected fibromodulin knock-out (FMOD-KO) mice to pressure overload by aortic banding, and overexpressed fibromodulin in cultured cardiomyocytes and cardiac fibroblasts using adenovirus. Fibromodulin was 3-10-fold upregulated in hearts of heart failure patients and mice. Both cardiomyocytes and cardiac fibroblasts expressed fibromodulin, and its expression was increased by pro-inflammatory stimuli. Without stress, FMOD-KO mice showed no cardiac phenotype. Upon aortic banding, left ventricles of FMOD-KO mice developed mildly exacerbated hypertrophic remodeling compared to wild-type mice, with increased cardiomyocyte size and altered infiltration of leukocytes. There were no differences in mortality, left ventricle dilatation, dysfunction or expression of heart failure markers. Although collagen amount and cross-linking were comparable in FMOD-KO and wild-type, overexpression of fibromodulin in cardiac fibroblasts in vitro decreased their migratory capacity and expression of fibrosis-associated molecules, i.e. the collagen-cross linking enzyme lysyl oxidase, transglutaminase 2 and periostin. In conclusion, despite a robust fibromodulin upregulation in clinical and experimental heart failure, FMOD-KO mice showed a relatively mild hypertrophic phenotype. In cultured cardiac fibroblasts, fibromodulin has anti-fibrotic effects.

Irisin alleviates pressure overload-induced cardiac hypertrophy by inducing protective autophagy via mTOR-independent activation of the AMPK-ULK1 pathway

In hypertrophic hearts, autophagic flux insufficiency is recognized as a key pathology leading to maladaptive cardiac remodeling and heart failure. This study aimed to illuminate the cardioprotective role and mechanisms of a new myokine and adipokine, irisin, in cardiac hypertrophy and remodeling. Adult male wild-type, mouse-FNDC5 (irisin-precursor)-knockout and FNDC5 transgenic mice received 4 weeks of transverse aortic constriction (TAC) alone or combined with intraperitoneal injection of chloroquine diphosphate (CQ). Endogenous FNDC5 ablation aggravated and exogenous FNDC5 overexpression attenuated the TAC-induced hypertrophic damage in the heart, which was comparable to the protection of irisin against cardiomyocyte hypertrophy induced by angiotensin II (Ang II) or phenylephrine (PE). Accumulated autophagosome and impaired autophagy flux occurred in the TAC-treated myocardium and Ang II- or PE-insulted cardiomyocytes. Irisin deficiency caused reduced autophagy and aggravated autophagy flux failure, whereas irisin overexpression or supplementation induced protective autophagy and improved autophagy flux, which were reversed by autophagy inhibitors Atg5 siRNA, 3-MA and CQ. Irisin boosted the activity of only AMPK but not Akt and MAPK family members in hypertrophic hearts and cultured cardiomyocytes and further activated ULK1 at Ser555 but not Ser757 and did not affect the mTOR-S6K axis. Blockage of AMPK and ULK1 with compund C and SBI-0206965, respectively, both abrogated irisin's protection against cardiomyocyte hypertrophic injury and reversed its induction of both autophagy and autophagy flux. Our results suggest that irisin protects against pressure overload-induced cardiac hypertrophy by inducing protective autophagy and autophagy flux via activating AMPK-ULK1 signaling.

Isoproterenol-induced cardiac ischemia and fibrosis: Plant-based approaches for intervention

Heart is the most active and incumbent organ of the body, which maintains blood flow, but due to various pathological reasons, several acute and chronic cardiac complications arise out of which myocardial infarction is one of the teething problems. Isoproterenol (ISP)-induced myocardial ischemia is a classical model to screen the cardioprotective effects of various pharmacological interventions. Phytochemicals present a novel option for treating various human maladies including those of the heart. A large number of plant products and their active ingredients have been screened for efficacy in ameliorating ISP-induced myocardial ischemia including coriander, curcumin, Momordica, quercetin, and Withania somnifera. These phytochemicals constituents may play key role in preventing disease and help in cardiac remodeling. Reactive oxygen species scavenging, antiinflammatory, and modulation of various molecular pathways such as Nrf2, NFкB, p-21 activated kinase 1 (PAK1), and p-smad2/3 signaling modulation have been implicated behind the claimed protection. In this review, we have provided a focused overview on the utility of ISP-induced cardiotoxicity, myocardial ischemia, and cardiac fibrosis for preclinical research. In addition, we have also surveyed molecular mechanism of various plant-based interventions screened for cardioprotective effect in ISP-induced cardiotoxicity, and their probable mechanistic profile is summarized.

Upregulation of lncRNA VDR/CASC15 induced by facilitates cardiac hypertrophy through modulating miR-432-5p/TLR4 axis

Sustained cardiac hypertrophy has threatened human health. With the development of human genome project, non-coding RNAs (ncRNAs) have attracted more and more attentions of researchers. As a subgroup of ncRNAs, long non-coding RNAs (lncRNAs) has been widely studied in human diseases, including cardiac hypertrophy. According to search results of bioinformatics website, lncRNA CASC15 potentially participates in the course of cardiac hypertrophy. According to the result of qRT-PCR, CASC15 expression was upregulated when cardiomyocytes were treated with Ang-II. Moreover, CASC15 was highly expressed in cardiac hypertrophic model. Upregulation of CASC15 was accompanied with some hypertrophic responses. To explore the specific biological function of CASC15 in cardiac hypertrophy, loss-of-function experiments were conducted in Ang-II-induced cardiomyocytes. Results of immunofluorence staining revealed that cell surface area enlarged by Ang-II was decreased when CASC15 was silenced. The expression levels of hypertrophic factors were attenuated by knockdown of CASC15. To detect the molecular mechanism by which CASC15 regulates the progression of cardiac hypertrophy, mechanism experiments were designed and carried out. It was found that CASC15 was activated by the transcription factor VDR. Furthermore, CASC15 can upregulate TLR4 by competitively binding miR-432-5p. In conclusion, Upregulation of lncRNA CASC15 induced by VDR facilitates cardiac hypertrophy via miR-432-5p/TLR4 axis.

Integrin β3 inhibits hypoxia-induced apoptosis in cardiomyocytes

Hypoxia-induced apoptosis plays an important role in cardiovascular diseases. Integrin β3 is one of the main integrin heterodimer receptors on the surface of cardiac myocytes. However, despite the important role that integrin β3 plays in the cardiovascular disease, its exact role in the hypoxia response remains unclear. Hence, in the present investigation we aimed to study the role of integrin β3 in hypoxia-induced apoptosis in H9C2 cells and primary rat myocardial cells. MTT assay, flow cytometry and TUNEL assay results showed that hypoxia inhibited cardiomyocyte proliferation and induced cardiomyocyte apoptosis. The expression levels of integrin β3 and HIF1α were upregulated in hypoxia-induced cardiomyocytes as revealed by real-time PCR and western blot analysis. Furthermore, knockdown of integrin β3 expression by siRNA increased hypoxia-induced cardiomyocyte apoptosis. In addition, integrin β3 overexpression weakened hypoxia-induced cardiomyocyte apoptosis. The protein expressions of integrin β3 and HIF1α were upregulated in acute myocardial infarction rat cardiac tissues compared with the control rat cardiac tissues. Our data suggest that integrin β3 plays a protective role in cardiomyocytes during hypoxia-induced apoptosis.

Oxidative Stress and Cardiac Remodeling: An Updated Edge

Background:

A common phenotype associated with heart failure is the development of cardiac hypertrophy. Cardiac hypertrophy occurs in response to stress, such as hypertension, coro-nary vascular disease, or myocardial infarction. The most critical pathophysiological conditions in-volved may include dilated hypertrophy, fibrosis and contractile malfunction. The intricate pathophys-iological mechanisms of cardiac hypertrophy have been the core of several scientific studies, which may help in opening a new avenue in preventive and curative procedures.

Objectives:

To our knowledge from the literature, the development of cardiac remodeling and hyper-trophy is multifactorial. Thus, in this review, we will focus and summarize the potential role of oxida-tive stress in cardiac hypertrophy development.

Conclusion:

Oxidative stress is considered a major stimulant for the signal transduction in cardiac cells pathological conditions, including inflammatory cytokines, and MAP kinase. The understanding of the pathophysiological mechanisms which are involved in cardiac hypertrophy and remodeling process is crucial for the development of new therapeutic plans, especially that the mortality rates re-lated to cardiac remodeling/dysfunction remain high

Implications of disturbances in circadian rhythms for cardiovascular health: A new frontier in free radical biology

Cell autonomous circadian "clock" mechanisms are present in virtually every organ, and generate daily rhythms that are important for normal physiology. This is especially relevant to the cardiovascular system, for example the circadian mechanism orchestrates rhythms in heart rate, blood pressure, cardiac contractility, metabolism, gene and protein abundance over the 24-h day and night cycles. Conversely, disturbing circadian rhythms (e.g. via shift work, sleep disorders) increases cardiovascular disease risk, and exacerbates cardiac remodelling and worsens outcome. Notably, reactive oxygen species (ROS) are important contributors to heart disease, especially the pathophysiologic damage that occurs after myocardial infarction (MI, heart attack). However, little is known about how the circadian mechanism, or rhythm desynchrony, is involved in these key pathologic stress responses. This review summarizes the current knowledge on circadian rhythms in the cardiovascular system, and the implications of rhythm disturbances for cardiovascular health. Furthermore, we highlight how free radical biology coincides with the pathogenesis of myocardial repair and remodelling after MI, and indicate a role for the circadian system in the oxidative stress pathways in the heart and brain after MI. This fusion of circadian biology with cardiac oxidative stress pathways is novel, and offers enormous potential for improving our understanding and treatment of heart disease.

Heart Disease and Relaxin: New Actions for an Old Hormone

The hormone relaxin has long been recognized for its involvement in maternal adaptation during pregnancy. However, discoveries during the past two decades on the mechanism of action of relaxin, its family of receptors, and newly described roles in attenuating ischemia/reperfusion (I/R) injury, inflammation, and arrhythmias have prompted vast interest in exploring its therapeutic potential in cardiovascular disease. These observations inspired recently concluded clinical trials in patients with acute heart failure. This review discusses our current understanding of the protective signaling pathways elicited by relaxin in the heart, and highlights important new breakthroughs about relaxin signaling that may pave the way to more carefully designed future trials.

Cardiac Progenitor Cells: The Matrix Has You

Components of the cardiac extracellular matrix (ECM) are synthesized by residing cells and are continuously remodeled by them. Conversely, residing cells (including primitive cells) receive constant biochemical and mechanical signals from the ECM that modulate their biology. The pathological progression of heart failure affects all residing cells, inevitably causing profound changes in ECM composition and architecture that, in turn, impact on cell phenotypes. Any regenerative medicine approach must aim at sustaining microenvironment conditions that favor cardiogenic commitment of therapeutic cells and minimize pro‐fibrotic signals, while conversely boosting the capacity of therapeutic cells to counteract adverse remodeling of the ECM. In this Perspective article, we discuss multiple issues about the features of an optimal scaffold for supporting cardiac tissue engineering strategies with cardiac progenitor cells, and, conversely, about the possible antifibrotic mechanisms induced by cell therapy. Stem Cells Translational Medicine2018;7:506–510

Oxidative Stress and Cardiac Remodeling: An Updated Edge

BACKGROUND

A common phenotype associated with heart failure is the development of cardiac hypertrophy. Cardiac hypertrophy occurs in response to stress, such as hypertension, coronary vascular disease, or myocardial infarction. The most critical pathophysiological conditions involved may include dilated hypertrophy, fibrosis and contractile malfunction. The intricate pathophysiological mechanisms of cardiac hypertrophy have been the core of several scientific studies, which may help in opening a new avenue in preventive and curative procedures.

OBJECTIVES

To our knowledge from the literature, the development of cardiac remodeling and hypertrophy is multifactorial. Thus, in this review, we will focus and summarize the potential role of oxidative stress in cardiac hypertrophy development.

CONCLUSION

Oxidative stress is considered a major stimulant for the signal transduction in cardiac cells pathological conditions, including inflammatory cytokines, and MAP kinase. The understanding of the pathophysiological mechanisms which are involved in cardiac hypertrophy and remodeling process is crucial for the development of new therapeutic plans, especially that the mortality rates related to cardiac remodeling/dysfunction remain high.

Idiopathic Pulmonary Fibrosis: Aging, Mitochondrial Dysfunction, and Cellular Bioenergetics

At present, the etiology of idiopathic pulmonary fibrosis (IPF) remains elusive. Over the past two decades, however, researchers have identified and described the underlying processes that result in metabolic dysregulation, metabolic reprogramming, and mitochondrial dysfunction observed in the cells of IPF lungs. Metabolic changes and mitochondrial dysfunction in IPF include decreased efficiency of electron transport chain function with increasing production of reactive oxygen species, decreased mitochondrial biogenesis, and impaired mitochondrial macroautophagy, a key pathway for the removal of dysfunctional mitochondria. Metabolic changes in IPF have potential impact on lung cell function, differentiation, and activation of fibrotic responses. These alterations result in activation of TGF-β and predispose to the development of pulmonary fibrosis. IPF is a disease of the aged, and many of these same bioenergetic changes are present to a lesser extent with normal aging, raising the possibility that these anticipated alterations in metabolic processes play important roles in creating susceptibility to the development of IPF. This review explores what is known regarding the cellular metabolic and mitochondrial changes that are found in IPF, and examines this body of literature to identify future research direction and potential points of intervention in the pathogenesis of IPF.

The lncRNA Plscr4 Controls Cardiac Hypertrophy by Regulating miR-214

Cardiac hypertrophy accompanied by maladaptive cardiac remodeling is the uppermost risk factor for the development of heart failure. Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) have various biological functions, and their vital role in the regulation of cardiac hypertrophy still needs to be explored. In this study, we demonstrated that lncRNA Plscr4 was upregulated in hypertrophic mice hearts and in angiotensin II (Ang II)–treated cardiomyocytes. Next, we observed that overexpression of Plscr4 attenuated Ang II-induced cardiomyocyte hypertrophy. Conversely, the inhibition of Plscr4 gave rise to cardiomyocyte hypertrophy. Furthermore, overexpression of Plscr4 attenuated TAC (transverse aortic constriction)-induced cardiac hypertrophy. Finally, we demonstrated that Plscr4 acted as an endogenous sponge of miR-214 and forced expression of Plscr4 downregulated miR-214 expression to promote Mfn2 and attenuate hypertrophy. In contrast, knockdown of Plscr4 upregulated miR-214 to induce cardiomyocyte hypertrophy. Additionally, luciferase assay showed that miR-214 was the direct target of Plscr4, and overexpression of miR-214 counteracted the anti-hypertrophy effect of Plscr4. Collectively, these findings identify Plscr4 as a negative regulator of cardiac hypertrophy in vivo and in vitro due to its regulation of the miR-214-Mfn2 axis, suggesting that Plscr4 might act as a therapeutic target for the treatment of cardiac hypertrophy and heart failure.

Orientin Reduces Myocardial Infarction Size via eNOS/NO Signaling and Thus Mitigates Adverse Cardiac Remodeling

Orientin is a flavonoid extracted from Chinese traditional herb, Polygonum orientale L. Previous study has reported that orientin protected myocardial from ischemia reperfusion injury. However, whether orientin could protect against cardiac remodeling after myocardial injury remains unclear. The aim of our study is to investigate the effects of orientin in the progression of cardiac remodeling after myocardial infarction (MI). Mice cardiac remodeling model was established by left coronary artery ligation surgery. Experimental groups were as follows: vehicle-sham, orientin-sham, vehicle-MI, and orientin-MI. Animals were treated with vehicle or orientin (40 mg/kg) for 25 days starting 3 days after surgery. After 4 weeks of MI, mice with orientin treatment had decreased mortality and improved cardiac function. Significantly, at 4 weeks post-MI, orientin treatment decreased fibrosis, inflammatory response, and cardiomyocyte apoptosis. Furthermore, orientin treatment attenuated the hypoxia-induced neonatal rat cardiomyocyte apoptosis and increased cell viability. Additionally, orientin supplementation mitigated oxidative stress in remodeling heart tissue and cardiomyocytes exposed to hypoxia as measured by 2′,7′-dichlorodihydrofluorescein diacetate fluorescent probe. Mechanistically, orientin promotes cardioprotection by activating the eNOS/NO signaling cascades, which was confirmed by eNOS inhibitor (L-NAME) in vitro and in vivo. Inhibition of oxidative stress by orientin via eNOS/NO signaling cascades in the heart may represent a potential therapy for cardiac remodeling.

Qiliqiangxin attenuates isoproterenol-induced cardiac remodeling in mice

BACKGROUND

To further explore the role of PPARγ in QL treatment, ISO-induced mice model and following methods were established.

METHODS

Cardiac remodeling on mice model was induced by isoproterenol (ISO) infusion or saline infusion as control for two weeks then divided into 4 groups, after that divided in 5 different treatment methods to investigate the role of PPARγ in QL therapy. Echocardiography and Masson's trichrome staining were respectively used to determine cardiac function and fibrosis. Immunoblotting was applied to evaluate the expression levels of proliferator-activated receptor-γ (PPARγ), Bax, Bcl, phospho-Akt (Ser473), Akt, phospho-P38 and P38, phosphor-ERK and ERK.

RESULTS

QL treatment improved left ventricular function, decreased apoptosis, and prevented myocardial fibrosis at the same time. Meanwhile, the PPARγ level was elevated with QL treatment in ISO-injected mice hearts. Inhibition of PPARγ activity blocked the protective effects of QL, while the activator of PPARγ did not provide additional benefit. Specifically, the results indicated a decline in PPARγ in ISO-infused mice and QL decreased the toxicity of ISO by improving the level of PPARγ.

CONCLUSIONS

Our study demonstrated that QL treatment provided cardioprotection against ISO-induced cardiac remodeling by improving PPARγ level, which could be as the potential therapeutic target in reversing cardiac remodeling and heart failure.

Sudden death: Neurogenic causes, prediction and prevention

Sudden death is a major health problem all over the world. The most common causes of sudden death are cardiac but there are also other causes such as neurological conditions (stroke, epileptic attacks and brain trauma), drugs, catecholamine toxicity, etc. A common feature of all these diverse pathologies underlying sudden death is the imbalance of the autonomic nervous system control of the cardiovascular system. This paper reviews different pathologies underlying sudden death with emphasis on the autonomic nervous system contribution, possibilities of early diagnosis and prognosis of sudden death using various clinical markers including autonomic markers (heart rate variability and baroreflex sensitivity), present possibilities of management and promising prevention by electrical neuromodulation.