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Differential microRNA-21 and microRNA-221 Upregulation in the Biventricular Failing Heart Reveals Distinct Stress Responses of Right Versus Left Ventricular Fibroblasts
Abstract
Background:
The failing right ventricle (RV) does not respond like the left ventricle (LV) to guideline-directed medical therapy of heart failure, perhaps due to interventricular differences in their molecular pathophysiology.
Methods:
Using the canine tachypacing-induced biventricular heart failure (HF) model, we tested the hypothesis that interventricular differences in microRNAs (miRs) expression distinguish failing RV from failing LV.
Results:
Severe RV dysfunction was indicated by elevated end-diastolic pressure (11.3±2.5 versus 5.7±2.0 mm Hg; P<0.0001) and diminished fractional area change (24.9±7.1 versus 48.0±3.6%; P<0.0001) relative to prepacing baselines. Microarray analysis of ventricular tissue revealed that miR-21 and miR-221, 2 activators of profibrotic and proliferative processes, increased the most, at 4- and 2-fold, respectively, in RV-HF versus RV-Control. Neither miR-21 or miR-221 was statistically significantly different in LV-HF versus LV-Control. These changes were accompanied by more extensive fibrosis in RV-HF than LV-HF. To test whether miR-21 and miR-221 upregulation is specific to RV cellular response to mechanical and hormonal stimuli associated with HF, we subjected fibroblasts and cardiomyocytes isolated from normal canine RV and LV to cyclic overstretch and aldosterone. These 2 stressors markedly upregulated miR-21 and miR-221 in RV fibroblasts but not in LV fibroblasts nor cardiomyocytes of either ventricle. Furthermore, miR-21/221 knockdown significantly attenuated RV but not LV fibroblast proliferation.
Conclusions:
We identified a novel, biological difference between RV and LV fibroblasts that might underlie distinctions in pathological remodeling of the RV in biventricular HF.
... Moreover, an artificial increase in miR-21 induced cardiomyocyte hypertrophy and the expression of a cardiac stress marker (namely, brain natriuretic peptide) [60]. miR-21 was also increased in the RV, but not the LV, of a group 2 PH canine model [48]. Interestingly, Chang and colleagues reported dynamic changes in miR-21 expression in chronic heart disease-associated PAH patients (CHD-PAH) [38]. ...
... Conversely, artificial miR-126 overexpression decreased SPRED-1 expression, improved RV endothelial cells' angiogenic capacity, and increased RV capillary density and function in MCT rats. Interestingly, miR-126 was also decreased in RVs from Sugen + hypoxia rats' models of PH [57] and in failing RVs from a dog model of group 2PH [48]. Beyond PAH, decreased miR-126 RV levels were associated with post-transplantation complications, such as cardiac allograft vasculopathy [23]. ...
... Functionally, miR-200b overexpression decreased protein kinase c alpha expression in both the RVs and the lungs of MCT rats. Powers and colleagues reported the impaired expression of 26 miRNAs, including increased miR-21 and miR-221, in RV samples harvested from a dog model of group 2PH [48]. Hormonal (aldosterone) and mechanical (stretch) stress increased miR-21 and miR-221 expression in canine RV fibroblasts (but not in LV fibroblasts). ...
There is an increasing recognition of the crucial role of the right ventricle (RV) in determining the functional status and prognosis in multiple conditions. In the past decade, the epigenetic regulation (DNA methylation, histone modification, and non-coding RNAs) of gene expression has been raised as a critical determinant of RV development, RV physiological function, and RV pathological dysfunction. We thus aimed to perform an up-to-date review of the literature, gathering knowledge on the epigenetic modifications associated with RV function/dysfunction. Therefore, we conducted a systematic review of studies assessing the contribution of epigenetic modifications to RV development and/or the progression of RV dysfunction regardless of the causal pathology. English literature published on PubMed, between the inception of the study and 1 January 2023, was evaluated. Two authors independently evaluated whether studies met eligibility criteria before study results were extracted. Amongst the 817 studies screened, 109 studies were included in this review, including 69 that used human samples (e.g., RV myocardium, blood). While 37 proposed an epigenetic-based therapeutic intervention to improve RV function, none involved a clinical trial and 70 are descriptive. Surprisingly, we observed a substantial discrepancy between studies investigating the expression (up or down) and/or the contribution of the same epigenetic modifications on RV function or development. This exhaustive review of the literature summarizes the relevant epigenetic studies focusing on RV in human or preclinical setting.
... For example, Taylor and Gercel-Taylor (2008) first proposed that exosomal miRNA-21 can act as a marker of ovarian cancer and even determine the progress of the disease. The therapeutic effects of exosomes vary with their type and concentration (Beltrami et al., 2017;Chuppa et al., 2018;Powers et al., 2020). As exosomes can regulate apoptosis, they can be used for therapy. ...
Cardiovascular diseases are the most common diseases threatening the health of the elderly, and the incidence and mortality rates associated with cardiovascular diseases remain high and are increasing gradually. Studies on the treatment and prevention of cardiovascular diseases are underway. Currently, several research groups are studying the role of exosomes and biomolecules incorporated by exosomes in the prevention, diagnosis, and treatment of clinical diseases, including cardiovascular diseases. Now, based on the results of published studies, this review discusses the characteristics, separation, extraction, and identification of exosomes, specifically the role of exosomal miRNAs in atherosclerosis, myocardial injury and infarction, heart failure, aortic dissection, myocardial fibrosis, ischemic reperfusion, atrial fibrillation, and other diseases. We believe that the observations noted in this article will aid in the prevention, diagnosis, and treatment of cardiovascular diseases.
... In addition, there were different expression patterns of miR-21 and miR-221 in CFs between failing RV and LV in a canine biventricular HF model. This may be one of the explanations that the failing RV does not respond like the LV to guideline-directed medical therapy of HF (99). Considering differences in genetic and embryonic developmental background, this result needs to be further confirmed in patients. ...
Cardiac remodeling is a pathophysiological process activated by diverse cardiac stress, which impairs cardiac function and leads to adverse clinical outcome. This remodeling partly attributes to cardiac fibrosis, which is a result of differentiation of cardiac fibroblasts to myofibroblasts and the production of excessive extracellular matrix within the myocardium. Non-coding RNAs mainly include microRNAs and long non-coding RNAs. These non-coding RNAs have been proved to have a profound impact on biological behaviors of various cardiac cell types and play a pivotal role in the development of cardiac fibrosis. This review aims to summarize the role of microRNAs and long non-coding RNAs in cardiac fibrosis associated with pressure overload, ischemia, diabetes mellitus, aging, atrial fibrillation and heart transplantation, meanwhile shed light on the diagnostic and therapeutic potential of non-coding RNAs for cardiac fibrosis.
... It was found that microRNA-21 expression was upregulated in cardiac fibroblasts of heart failure patients, which was significantly higher than its expression in normal cardiomyocytes. Under stressful conditions, microRNA-21 overexpression in cardiac fibroblasts can significantly activate ERK-MAPK pathway proteins and promote fibroblast proliferation and fibrosis [26]. ...
Objective:
This study is to assess the application of combined detection of echocardiography and serum N-terminal pro B-type natriuretic peptide (NT-ProBNP) in the diagnosis of diastolic heart failure (DHF) and its effect on left ventricular morphology and diastolic function.
Methods:
Thirty patients with DHF with enrolled in our hospital between January 2019 and January 2021 were included in the experimental group, and thirty healthy individuals during the same period were included in the control group. The blood pressure, heart rate (HR), left ventricular morphology, diastolic function, and serum NT-ProBNP levels were compared between the two groups.
Results:
DHF was associated with higher levels of diastolic blood pressure (DBP), systolic blood pressure (SBP), HR, left ventricular diameter (LVD), interventricular septum thickness (IVST), left ventricular posterior wall thickness (LVPWT), left atrial volume index (LAVI), left ventricular end-diastolic volume (LVEDV), serum NT-ProBNP, maximum early ventricular filling velocity/early diastolic velocity of the mitral annulus (E/Ea) ratio, and aortic regurgitation (AR) and lower levels of left ventricular ejection fraction (LVEF), flow propagation velocity (VP), and systolic/diastolic (S/D) ratio versus healthy subjects (all at P < 0.05).
Conclusion:
The combined detection of echocardiography and serum NT-ProBNP yields a high clinical value in the diagnosis of DHF deficiency, as it can accurately evaluate the patient's left heart morphology and diastolic function, so it is worthy of clinical promotion and application.
... There are baseline differences in miRNA expression between the RV and LV (140). RV-specific miRNAs that are dysregulated during RV dysfunction: miR-21, -28, -34a, -93, -126/VEGF, -127, -130a, -146b, -148a, -197, -208/ Mef2c, -221, and let-7e (39,133,(140)(141)(142)(143)145). ...
Right ventricle (RV) dysfunction is the strongest predictor of mortality in pulmonary arterial hypertension (PAH), but, at present, there are no therapies directly targeting the failing RV. Although there are shared molecular mechanisms in both RV and left ventricle (LV) dysfunction, there are important differences between the 2 ventricles that may allow for the development of RV-enhancing or RV-directed therapies. In this review, we discuss the current understandings of the dysregulated pathways that promote RV dysfunction, highlight RV-enriched or RV-specific pathways that may be of particular therapeutic value, and summarize recent and ongoing clinical trials that are investigating RV function in PAH. It is hoped that development of RV-targeted therapies will improve quality of life and enhance survival for this deadly disease.
... The atrial cardiac fibroblasts proliferate at a rate three folds higher than ventricular cardiac fibroblasts and this mechanisms is believed to protect the atria while the ventricle undergoes pressure or volume associated remodeling (Rizvi et al., 2016). Furthermore, a recent paper indicates that cyclic overstretch and aldosterone modulates pro-proliferative and profibrotic activators, mi-R21 and miR-221 in the RV but not the LV in vitro and in vivo (Powers et al., 2020). ...
Pulmonary arterial hypertension (PAH) is a syndrome diagnosed by increased mean pulmonary artery (PA) pressure and resistance and normal pulmonary capillary wedge pressure. PAH is characterized pathologically by distal pulmonary artery remodeling, increased pulmonary vascular resistance, and plexiform lesions (PLs). Right ventricular fibrosis and hypertrophy, leading to right ventricular failure, are the main determinants of mortality in PAH. Recent work suggests that right ventricular fibrosis results from resident cardiac fibroblast activation and conversion to myofibroblasts, leading to replacement of contractile cardiomyocytes with nondistensible tissue incapable of conductivity or contractility. However, the origins, triggers, and consequences of myofibroblast expansion and its pathophysiological relationship with PAH are unclear. Recent advances indicate that signals generated by adaptive and innate immune cells may play a role in right ventricular fibrosis and remodeling. This review summarizes recent insights into the mechanisms by which adaptive and innate immune signals participate in the transition of cardiac fibroblasts to activated myofibroblasts and highlights the existing gaps of knowledge as relates to the development of right ventricular fibrosis. Adaptive and maladaptive cardiac remodeling results from the secretion of pro‐inflammatory and profibrotic cytokines and chemokines originating in macrophages (innate immune responses) and helper T cells (adaptive immunity). Direct conversion of one cell type to another may also be a mechanism of disease pathology in the setting of PAH.
... Cardiac fibroblasts play a key role in the process of myocardial remodeling and myocardial fibrosis, which will eventually lead to heart failure [22]. Many studies have clearly pointed out that cardiac fibroblasts are one of the main types of cell components in the heart, accounting for a relatively high percentage of the total number of cardiac cells, accounting for about 30 %-60 %. ...
Cardiac fibroblasts play a key role in the process of myocardial remodeling and myocardial fibrosis, which will eventually lead to heart failure. Quercetin Dihydrate has been studied in cardiovascular disease, but its effect on myocardial fibrosis is not clear. Here, cardiac remodeling was induced by infusion of Ang II (1000 ng/kg/min) for 2 weeks in mice. Quercetin Dihydrate was injected intraperitoneally for 25 mM/kg body weight (BW) once two days. We found that Quercetin Dihydrate significantly reduced cardiac contractile function, fibrosis, inflammation and myocardial hypertrophy induced by Ang II. Quercetin Dihydrate could inhibit the expression of Collagen I and Collagen III, which are the markers of fibroblast differentiation. We also verified the inhibitory effect of Quercetin Dihydrate on the proliferation and differentiation of fibroblasts induced by angiotensin II in vitro. Our results show that quercetin dihydrate plays a key role in the progression of myocardial fibrosis and suggests that Quercetin Dihydrate may be a promising drug for the treatment of myocardial fibrosis.
MicroRNAs (miRNAs) are small non-coding RNAs that function by post-transcriptional regulation of gene expression. Their stability and abundance in tissue and body fluids makes them promising potential tools for both the diagnosis and prognosis of diseases and attractive therapeutic targets in humans and dogs. Studies of miRNA expression in normal and disease processes in dogs are scarce compared to studies published on miRNA expression in human disease. In this literature review, we identified 461 peer-reviewed papers from database searches using the terms “canine,” “dog,” “miRNA,” and “microRNA”; we screened 244 for inclusion criteria and then included a total of 148 original research peer-reviewed publications relating to specific miRNA expression in canine samples. We found an overlap of miRNA expression changes between the four groups evaluated (normal processes, non-infectious and non-inflammatory conditions, infectious and/or inflammatory conditions, and neoplasia) in 39 miRNAs, 83 miRNAs in three of the four groups, 110 miRNAs in two of the three groups, where 158 miRNAs have only been reported in one of the groups. Additionally, the mechanism of action of these overlapping miRNAs varies depending on the disease process, elucidating a need for characterization of the mechanism of action of each miRNA in each disease process being evaluated. Herein we also draw attention to the lack of standardization of miRNA evaluation, consistency within a single evaluation method, and the need for standardized methods for a direct comparison.
Myocardial fibrosis resulting from the excessive deposition of collagen fibers through the myocardium is a common histopathologic finding in a wide range of cardiovascular diseases, including congenital anomalies. Interstitial fibrosis has been identified as a major cause of myocardial dysfunction since it distorts the normal architecture of the myocardium and impairs the biological function and properties of the interstitium. This review summarizes current knowledge on the mechanisms and detrimental consequences of myocardial fibrosis in heart failure and arrhythmias, discusses the usefulness of available imaging techniques and circulating biomarkers to assess this entity and reviews the current body of evidence regarding myocardial fibrosis in the different subsets of congenital heart diseases with implications in research and treatment.
The purinoceptor 7 receptor (P2X7R) plays an important role in promoting inflammation in response to accumulating damage-associated molecular patterns (DAMPs) released from stressed or apoptotic cells and has been connected to various pathological conditions. The initial investment by large pharmaceutical companies such as AstraZeneca and Pfizer led to the development of several classes of P2X7R antagonists for the treatment of rheumatoid arthritis and Crohn’s disease. While these compounds showed early promise as therapeutic agents and were found to potently inhibit adenosine triphosphate (ATP)-induced release of interleukin 1 beta (IL-1β) in patient-derived monocytes primed with lipopolysaccharide (LPS), they failed to elicit a therapeutic benefit in phase II clinical trials. Within the last 10 years, a wealth of strong preclinical and clinical evidence has implicated IL-1β as an aggressor in the development and progression of cardiovascular diseases, a cytokine modulated by the P2X7R. On account of the immune-mediated events that regulate atherosclerosis, antagonism of the P2X7R has been proposed as a therapeutic strategy due to the unique functionality of the receptor as an instigator of sterile inflammation. Here, we review the success and failures in P2X7R drug development to evaluate the major barriers to successful clinical translation of P2X7R antagonists. These avenues should be addressed by researchers and pharmaceutical companies to ensure future clinical success in the treatment of CAD.
Pulmonary hypertension (PH) is a devastating condition characterized by pulmonary vascular remodelling, leading to progressive increase in pulmonary artery pressure and subsequent right ventricular failure. Aldosterone and the mineralocorticoid receptor (MR), a nuclear transcription factor, are key drivers of cardiovascular disease and MR antagonists are well-established in heart failure. Now, a growing body of evidence points at a detrimental role of MR in PH. Pharmacological MR blockade attenuated PH and prevented RV failure in experimental models. Mouse models with cell selective MR deletion suggest that this effect is mediated by MR in endothelial cells. While the evidence from experimental studies appears convincing, the available clinical data on MR antagonist use in patients with PH is more controversial. Integrated analysis of clinical data together with MR-dependent molecular alterations may provide insights why some patients respond to MRA treatment while others do not. Potential ways to identify MRA ‘responders’ include the analysis of underlying PH causes, stage of disease, or sex, as well as new biomarkers.
Ligamentum flavum hypertrophy (LFH) leads to lumbar spinal stenosis (LSS) caused by LF tissue inflammation and fibrosis. Emerging evidence has indicated that dysregulated microRNAs (miRNAs) have an important role in inflammation and fibrosis. Mechanical stress (MS) has been explored as an initiating step in LFH pathology progression; the inflammation‐related miRNAs induced after mechanical stress have been implicated in fibrosis pathology. However, the pathophysiological mechanism of MS‐miRNAs‐LFH remains to be elucidated. Using miRNAs sequencing analysis and subsequent confirmation with qRT‐PCR assays, we identified the decreased expression of miR‐10396b‐3p and increased expression of IL‐11 (interleukin‐11) as responses to the development of LSS in hypertrophied LF tissues. We also found that IL‐11 is positively correlated with fibrosis indicators of collagen I and collagen III. The up‐regulation of miR‐10396b‐3p significantly decreased the level of IL‐11 expression, whereas miR‐10396b‐3p down‐regulation increased IL‐11 expression in vitro. Luciferase reporter assay indicates that IL‐11 is a direct target of miR‐10396b‐3p. Furthermore, cyclic mechanical stress inhibits miR‐10396b‐3p and induces IL‐11, collagen I, and collagen III in vitro. Our results showed that overexpression of miR‐10396b‐3p suppresses MS‐induced LFH by inhibiting collagen I and III via the inhibition of IL‐11. These data suggest that the MS‐miR‐10396b‐3p‐IL‐11 axis plays a key role in the pathological progression of LFH.
Diffuse myocardial fibrosis resulting from the excessive deposition of collagen fibres through the entire myocardium is encountered in a number of chronic cardiac diseases. This lesion results from alterations in the regulation of fibrillary collagen turnover by fibroblasts, facilitating the excessive deposition of type I and type III collagen fibres within the myocardial interstitium and around intramyocardial vessels. The available evidence suggests that, beyond the extent of fibrous deposits, collagen composition and the physicochemical properties of the fibres are also relevant in the detrimental effects of diffuse myocardial fibrosis on cardiac function and clinical outcomes in patients with heart failure. In this regard, findings from the past 20 years suggest that various clinicopathological phenotypes of diffuse myocardial fibrosis exist in patients with heart failure. In this Review, we summarize the current knowledge on the mechanisms and detrimental consequences of diffuse myocardial fibrosis in heart failure. Furthermore, we discuss the validity and usefulness of available imaging techniques and circulating biomarkers to assess the clinicopathological variation in this lesion and to track its clinical evolution. Finally, we highlight the currently available and potential future therapeutic strategies aimed at personalizing the prevention and reversal of diffuse myocardial fibrosis in patients with heart failure.
Background and purpose:
The diverse causes of right-sided heart failure (RHF) include, among others, primary cardiomyopathies with right ventricular (RV) involvement, RV ischemia and infarction, volume loading caused by cardiac lesions associated with congenital heart disease and valvular pathologies, and pressure loading resulting from pulmonic stenosis or pulmonary hypertension from a variety of causes, including left-sided heart disease. Progressive RV dysfunction in these disease states is associated with increased morbidity and mortality. The purpose of this scientific statement is to provide guidance on the assessment and management of RHF.
Methods:
The writing group used systematic literature reviews, published translational and clinical studies, clinical practice guidelines, and expert opinion/statements to summarize existing evidence and to identify areas of inadequacy requiring future research. The panel reviewed the most relevant adult medical literature excluding routine laboratory tests using MEDLINE, EMBASE, and Web of Science through September 2017. The document is organized and classified according to the American Heart Association to provide specific suggestions, considerations, or reference to contemporary clinical practice recommendations.
Results:
Chronic RHF is associated with decreased exercise tolerance, poor functional capacity, decreased cardiac output and progressive end-organ damage (caused by a combination of end-organ venous congestion and underperfusion), and cachexia resulting from poor absorption of nutrients, as well as a systemic proinflammatory state. It is the principal cause of death in patients with pulmonary arterial hypertension. Similarly, acute RHF is associated with hemodynamic instability and is the primary cause of death in patients presenting with massive pulmonary embolism, RV myocardial infarction, and postcardiotomy shock associated with cardiac surgery. Functional assessment of the right side of the heart can be hindered by its complex geometry. Multiple hemodynamic and biochemical markers are associated with worsening RHF and can serve to guide clinical assessment and therapeutic decision making. Pharmacological and mechanical interventions targeting isolated acute and chronic RHF have not been well investigated. Specific therapies promoting stabilization and recovery of RV function are lacking.
Conclusions:
RHF is a complex syndrome including diverse causes, pathways, and pathological processes. In this scientific statement, we review the causes and epidemiology of RV dysfunction and the pathophysiology of acute and chronic RHF and provide guidance for the management of the associated conditions leading to and caused by RHF.
Background:
Right ventricular (RV) dysfunction is recognized as a major prognostic factor in left-sided heart failure (HF). However, the relative contribution of RV dysfunction in HF with preserved (HFpEF) vs. reduced ejection fraction (HFrEF) is unclear.
Methods and results:
Right ventricular longitudinal strain (RVLS), tricuspid annular plane systolic excursion (TAPSE) and pulmonary artery systolic pressure (PASP) were determined by echocardiography in 657 age- and gender-matched groups of patients with HFpEF [left ventricular ejection fraction (LVEF) ≥50%; n=219] and HFrEF (LVEF <50%; n=219) and in controls without HF (n=219) from an Asian population-based cohort study. Across control to HFpEF and HFrEF groups, RV function deteriorated as measured by RVLS (-26.7 ± 5%, -22.7±6.6% and -18.2 ± 6.7%, respectively) and TAPSE (21.0 ± 3.9, 17.5 ± 5.1 and 14.7 ± 4.7 mm, respectively), whereas PASP increased (26.8 ± 7.1, 34.5 ± 11.9 and 39.3 ± 16.2 mmHg, respectively) (all P<0.001). Controlling for PASP in control, HFpEF and HFrEF subjects, the magnitude of RVLS/PASP (-1.06 ± 0.32, -0.75 ± 0.32 and -0.56 ± 0.36, respectively) and TAPSE/PASP ratios (0.83 ± 0.23, 0.54 ± 0.24 and 0.55 ± 0.29, respectively) similarly decreased across groups. Right ventricular dysfunction (by both TAPSE and RVLS) was independently associated with left ventricular systolic dysfunction and atrial fibrillation, but not with PASP. Among patients with HF, both TAPSE/PASP and RVLS/PASP ratios were related to the composite endpoint of all-cause death and HF hospitalization, even after multivariable adjustment [hazard ratio (HR) 0.33; 95% confidence interval (CI) 0.14-0.74 and HR 3.09; 95% CI 1.52-6.26, respectively], with no difference between HFrEF and HFpEF.
Conclusions:
Right ventricular dysfunction is present in HFpEF and is even more pronounced in HFrEF for any given degree of pulmonary hypertension. It is independently predicted by left ventricular dysfunction but not by PASP. Right ventricular-arterial coupling is prognostically important in HF regardless of LVEF.
Vascular endothelial growth factor (VEGF)-B activates cytoprotective/antiapoptotic and minimally angiogenic mechanisms via VEGF receptors. Therefore, VEGF-B might be an ideal candidate for the treatment of dilated cardiomyopathy, which displays modest microvascular rarefaction and increased rate of apoptosis.
This study evaluated VEGF-B gene therapy in a canine model of tachypacing-induced dilated cardiomyopathy.
Chronically instrumented dogs underwent cardiac tachypacing for 28 days. Adeno-associated virus serotype 9 viral vectors carrying VEGF-B167 genes were infused intracoronarily at the beginning of the pacing protocol or during compensated heart failure. Moreover, we tested a novel VEGF-B167 transgene controlled by the atrial natriuretic factor promoter.
Compared with control subjects, VEGF-B167 markedly preserved diastolic and contractile function and attenuated ventricular chamber remodeling, halting the progression from compensated to decompensated heart failure. Atrial natriuretic factor-VEGF-B167 expression was low in normally functioning hearts and stimulated by cardiac pacing; it thus functioned as an ideal therapeutic transgene, active only under pathological conditions.
Our results, obtained with a standard technique of interventional cardiology in a clinically relevant animal model, support VEGF-B167 gene transfer as an affordable and effective new therapy for nonischemic heart failure.
Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Heart failure (HF) causes left-atrial (LA) and left-ventricular (LV) remodeling, with particularly-prominent changes in LA that create a substrate for atrial fibrillation (AF). MicroRNAs (miRs) are potential regulators in cardiac remodeling. This study evaluated time-dependent miR expression-changes in LA and LV tissue, fibroblasts and cardiomyocytes in experimental HF. HF was induced in dogs by ventricular tachypacing (varying periods, up to 2 weeks). Following screening-microarray, 15 miRs were selected for detailed real-time qPCR assay. Extracellular matrix mRNA-expression was assessed by qPCR. Tachypacing time-dependently reduced LV ejection-fraction, increased LV-volume and AF-duration, and caused tissue-fibrosis with LA changes greater than LV. Tissue miR-expression significantly changed in LA for 10 miRs; in LV for none. Cell-selective analysis showed significant time-dependent changes in LA-fibroblasts for 10/15 miRs, LV-fibroblasts 8/15, LA-cardiomyocytes in 6/15 and LV-cardiomyocytes 3/15. Cell-expression specificity did not predict cell-specificity of VTP-induced expression-changes, e.g. 4/6 cardiomyocyte-selective miRs changed almost exclusively in fibroblasts (miR-1, miR-208b, miR133a/b). Thirteen miRs directly implicated in fibrosis/extracellular-matrix regulation were prominently changed: 9/13 showed fibroblast-selective alterations and 5/13 LA-selective. Multiple miRs changed in relation to associated extracellular-matrix targets. Experimental HF causes tissue and cell-type selective, time-dependent changes in cardiac miR-expression. Expression-changes are greater in LA versus LV, and greater in fibroblasts than cardiomyocytes, even for most cardiomyocyte-enriched miRs. This study, the first to examine time, chamber and cell-type selective changes in an experimental model of HF, suggests that multiple miR-changes underlie the atrial-selective fibrotic response and emphasize the importance of considering cell-specificity of miR expression-changes in cardiac remodeling paradigms.
MicroRNAs (miRs) are small, noncoding RNAs that are emerging as crucial regulators of cardiac remodeling in left ventricular hypertrophy (LVH) and failure (LVF). However, there are no data on their role in right ventricular hypertrophy (RVH) and failure (RVF). This is a critical question given that the RV is uniquely at risk in patients with congenital right-sided obstructive lesions and in those with systemic RVs. We have developed a murine model of RVH and RVF using pulmonary artery constriction (PAC). miR microarray analysis of RV from PAC vs. control demonstrates altered miR expression with gene targets associated with cardiomyocyte survival and growth during hypertrophy (miR 199a-3p) and reactivation of the fetal gene program during heart failure (miR-208b). The transition from hypertrophy to heart failure is characterized by apoptosis and fibrosis (miRs-34, 21, 1). Most are similar to LVH/LVF. However, there are several key differences between RV and LV: four miRs (34a, 28, 148a, and 93) were upregulated in RVH/RVF that are downregulated or unchanged in LVH/LVF. Furthermore, there is a corresponding downregulation of their putative target genes involving cell survival, proliferation, metabolism, extracellular matrix turnover, and impaired proteosomal function. The current study demonstrates, for the first time, alterations in miRs during the process of RV remodeling and the gene regulatory pathways leading to RVH and RVF. Many of these alterations are similar to those in the afterload-stressed LV. miRs differentially regulated between the RV and LV may contribute to the RVs increased susceptibility to heart failure.
MicroRNAs inhibit mRNA translation or promote mRNA degradation by binding complementary sequences in 3' untranslated regions of target mRNAs. MicroRNA-21 (miR-21) is upregulated in response to cardiac stress, and its inhibition by a cholesterol-modified antagomir has been reported to prevent cardiac hypertrophy and fibrosis in rodents in response to pressure overload. In contrast, we have shown here that miR-21-null mice are normal and, in response to a variety of cardiac stresses, display cardiac hypertrophy, fibrosis, upregulation of stress-responsive cardiac genes, and loss of cardiac contractility comparable to wild-type littermates. Similarly, inhibition of miR-21 through intravenous delivery of a locked nucleic acid-modified (LNA-modified) antimiR oligonucleotide also failed to block the remodeling response of the heart to stress. We therefore conclude that miR-21 is not essential for pathological cardiac remodeling.
Pulmonary hypertension on heart failure (HF) limits exercise capacity and survival probably because of associated right ventricular (RV) failure. This study investigated the mechanisms of RV function adaptation to early pulmonary hypertension in experimental HF. Seven weeks of rapid ventricular pacing in six dogs induced a HF characterized by cardiomegaly and decreased left ventricular ejection fraction. Compared with eight control dogs, pulmonary hypertension was borderline, with a mean pulmonary artery pressure increased to only 23 ± 2 (means ± SE) mmHg. However, the pulmonary vascular impedance spectrum was globally shifted to higher pressures, with an increase in 0 Hz impedance (resistance) to 662 ± 69 vs. 455 ± 41 dynes·cm(-5)·m(2) in controls (P < 0.01) and in characteristic impedance to 183 ± 20 vs. 104 ± 7 dynes·cm(-5)·m(2) in controls (P < 0.01). There was no change in RV end-systolic elastance (Ees), but arterial elastance (Ea) was increased to 1.8 ± 0.3 vs. 0.9 ± 0.1 mmHg/ml in controls so that RV-arterial coupling defined by the Ees-to-Ea ratio (Ees/Ea) was decreased to 0.8 ± 0.1 vs. 1.5 ± 0.1 in controls (P < 0.01). Inhaled nitric oxide, 40 ppm or 5 μg·kg(-1)·min(-1) nitroprusside i.v., did not affect Ees/Ea. Fifty milligrams (i.v.) of milrinone increased Ees/Ea to 1.6 ± 0.2 by an isolated increase in Ees. We conclude that overpacing-induced HF is accompanied by a borderline pulmonary hypertension but profound RV-arterial uncoupling explained by the failure of RV systolic function to adapt combined effects of increased pulmonary arterial resistance and elastance.
MicroRNAs comprise a broad class of small non-coding RNAs that control expression of complementary target messenger RNAs. Dysregulation of microRNAs by several mechanisms has been described in various disease states including cardiac disease. Whereas previous studies of cardiac disease have focused on microRNAs that are primarily expressed in cardiomyocytes, the role of microRNAs expressed in other cell types of the heart is unclear. Here we show that microRNA-21 (miR-21, also known as Mirn21) regulates the ERK-MAP kinase signalling pathway in cardiac fibroblasts, which has impacts on global cardiac structure and function. miR-21 levels are increased selectively in fibroblasts of the failing heart, augmenting ERK-MAP kinase activity through inhibition of sprouty homologue 1 (Spry1). This mechanism regulates fibroblast survival and growth factor secretion, apparently controlling the extent of interstitial fibrosis and cardiac hypertrophy. In vivo silencing of miR-21 by a specific antagomir in a mouse pressure-overload-induced disease model reduces cardiac ERK-MAP kinase activity, inhibits interstitial fibrosis and attenuates cardiac dysfunction. These findings reveal that microRNAs can contribute to myocardial disease by an effect in cardiac fibroblasts. Our results validate miR-21 as a disease target in heart failure and establish the therapeutic efficacy of microRNA therapeutic intervention in a cardiovascular disease setting.
A fundamental feature of the architecture and functional design of vertebrate animals is a stroma, composed of extracellular matrix and mesenchymal cells, which provides a structural scaffold and conduit for blood and lymphatic vessels, nerves, and leukocytes. Reciprocal interactions between mesenchymal and epithelial cells are known to play a critical role in orchestrating the development and morphogenesis of tissues and organs, but the roles played by specific stromal cells in controlling the design and function of tissues remain poorly understood. The principal cells of stromal tissue are called fibroblasts, a catch-all designation that belies their diversity. We characterized genome-wide patterns of gene expression in cultured fetal and adult human fibroblasts derived from skin at different anatomical sites. Fibroblasts from each site displayed distinct and characteristic transcriptional patterns, suggesting that fibroblasts at different locations in the body should be considered distinct differentiated cell types. Notable groups of differentially expressed genes included some implicated in extracellular matrix synthesis, lipid metabolism, and cell signaling pathways that control proliferation, cell migration, and fate determination. Several genes implicated in genetic diseases were found to be expressed in fibroblasts in an anatomic pattern that paralleled the phenotypic defects. Finally, adult fibroblasts maintained key features of HOX gene expression patterns established during embryogenesis, suggesting that HOX genes may direct topographic differentiation and underlie the detailed positional memory in fibroblasts.
Pressure overload causes cardiac fibroblast activation and transdifferentiation, leading to increased interstitial fibrosis formation and subsequently myocardial stiffness, diastolic and systolic dysfunction, and eventually heart failure. A better understanding of the molecular mechanisms underlying pressure overload-induced cardiac remodeling and fibrosis will have implications for heart failure treatment strategies. The microRNA (miRNA)-221/222 family, consisting of miR-221-3p and miR-222-3p, is differentially regulated in mouse and human cardiac pathology and inversely associated with kidney and liver fibrosis. We investigated the role of this miRNA family during pressure overload-induced cardiac remodeling. In myocardial biopsies of patients with severe fibrosis and dilated cardiomyopathy or aortic stenosis, we found significantly lower miRNA-221/222 levels as compared to matched patients with nonsevere fibrosis. In addition, miRNA-221/222 levels in aortic stenosis patients correlated negatively with the extent of myocardial fibrosis and with left ventricular stiffness. Inhibition of both miRNAs during AngII (angiotensin II)-mediated pressure overload in mice led to increased fibrosis and aggravated left ventricular dilation and dysfunction. In rat cardiac fibroblasts, inhibition of miRNA-221/222 derepressed TGF-β (transforming growth factor-β)-mediated profibrotic SMAD2 (mothers against decapentaplegic homolog 2) signaling and downstream gene expression, whereas overexpression of both miRNAs blunted TGF-β-induced profibrotic signaling. We found that the miRNA-221/222 family may target several genes involved in TGF-β signaling, including JNK1 (c-Jun N-terminal kinase 1), TGF-β receptor 1 and TGF-β receptor 2, and ETS-1 (ETS proto-oncogene 1). Our findings show that heart failure-associated downregulation of the miRNA-221/222 family enables profibrotic signaling in the pressure-overloaded heart.
Right ventricular (RV) remodelling is a lesser understood process of the chronic, progressive transformation of the RV structure leading to reduced functional capacity and subsequent failure. Besides conditions concerning whole hearts, some pathology selectively affects the RV, leading to a distinct RV-specific clinical phenotype. MicroRNAs have been identified as key regulators of biological processes that drive the progression of chronic diseases. The role of microRNAs in diseases affecting the left ventricle has been studied for many years, however there is still limited information on microRNAs specific to diseases in the right ventricle. Here, we review recently described details on the expression, regulation, and function of microRNAs in the pathological remodelling of the right heart. Recently identified strategies using microRNAs as pharmacological targets or biomarkers will be highlighted. Increasing knowledge of pathogenic microRNAs will finally help improve our understanding of underlying distinct mechanisms and help utilize novel targets or biomarkers to develop treatments for patients suffering from right heart diseases. © Published on behalf of the European Society of Cardiology. All rights reserved.
Combined pulmonary insufficiency (PI) and stenosis (PS) is a common long-term sequela after repair of many forms of congenital heart disease, causing progressive right ventricular (RV) dilation and failure. Little is known of the mechanisms underlying this combination of preload and afterload stressors. We developed a murine model of PI and PS (PI+PS) to identify clinically relevant pathways and biomarkers of disease progression. Diastolic dysfunction was induced (restrictive RV filling, elevated RV end-diastolic pressures) at 1 month after generation of PI+PS and progressed to systolic dysfunction (decreased RV shortening) by 3 months. RV fibrosis progressed from 1 month (4.4% ± 0.4%) to 3 months (9.2% ± 1%), along with TGF-β signaling and tissue expression of profibrotic miR-21. Although plasma miR-21 was upregulated with diastolic dysfunction, it was downregulated with the onset of systolic dysfunction), correlating with RV fibrosis. Plasma miR-21 in children with PI+PS followed a similar pattern. A model of combined RV volume and pressure overload recapitulates the evolution of RV failure unique to patients with prior RV outflow tract surgery. This progression was characterized by enhanced TGF-β and miR-21 signaling. miR-21 may serve as a plasma biomarker of RV failure, with decreased expression heralding the need for valve replacement.
This study was performed to determine the accuracy of right ventricular (RV) longitudinal strain (LS) in predicting myocardial fibrosis in patients with severe heart failure (HF) undergoing heart transplantation.
RVLS plays a key role in the evaluation of its systolic performance and clinical outcome in patients with refractory HF.
We studied 27 patients with severe systolic HF (ejection fraction ≤25% and New York Heart Association functional class III to IV, despite full medical therapy and cardiac resynchronization therapy) using echocardiography before heart transplantation. RV free wall LS, right atrial LS, sphericity index (SI), and tricuspid annular plane systolic excursion (TAPSE) were all measured. Upon removal of the heart, from the myocardial histologic analysis, the ratio of the fibrotic to the total sample area determined the extent of fibrosis (%).
RV myocardial fibrosis correlated with RV free wall LS (r = 0.80; p < 0.0001), SI (r = 0.42; p = 0.01) and VO2 max (r = -0.41; p = 0.03), with a poor correlation with TAPSE (r = -0.34; p = 0.05) and right arterial LS (r = -0.37; p = 0.03). Stepwise multivariate analysis showed that RV free wall LS (β = 0.701, p < 0.0001) was independently associated with RV fibrosis (overall model R(2) = 0.64, p < 0.0001). RV free wall LS was the main determinant of myocardial fibrosis. In the subgroup of patients with severe RV fibrosis, RV free wall LS had the highest diagnostic accuracy for detecting severe myocardial fibrosis (area under the curve = 0.87; 95% confidence interval: 0.80 to 0.94).
In late-stage HF patients, the right ventricle is enlarged, with reduced systolic function due to significant myocardial fibrosis. RV free wall myocardial deformation is the most accurate functional measure that correlates with the extent of RV myocardial fibrosis and functional capacity.
Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Heart failure is a leading cause of death but very little is known about right ventricular (RV) failure (RVF) and right ventricular recovery (RVR). A robust animal model of reversible, RVF does not exist, which currently limits research opportunities and clinical progress. We sought to develop an animal model of reversible, pressure-overload RVF to study RVF and RVR.
Fifteen New Zealand rabbits underwent implantation of a fully implantable, adjustable, pulmonary artery band. Animals were assigned to the control, RVF, and RVR groups (n = 5 for each). For the RVF and RVR groups, the pulmonary artery bands were serially tightened to create RVF and released for RVR. Echocardiographic, cardiac magnetic resonance imaging, and histologic analysis were performed.
RV chamber size and wall thickness increased during RVF and regressed during RVR. RV volumes were 1023 μL ± 123 for control, 2381 μL ± 637 for RVF, and 635 μL ± 549 for RVR, and RV wall thicknesses were 0.98 mm ± 0.12 for controls (P = 0.05), 1.72 mm ± 0.60 for RVF, and 1.16 mm ± 0.03 for RVR animals (P = 0.04), respectively. Similarly, heart weight, liver weight, cardiomyocyte size, and the degree of cardiac and hepatic fibrosis increased with RVF and decreased during RVR.
We report an animal model of chronic, reversible, pressure-overload RVF to study RVF and RVR. This model will be used for preclinical studies that improve our understanding of the mechanisms of RVF and that develop and test RV protective and RVR strategies to be studied later in humans.
Copyright © 2015 Elsevier Inc. All rights reserved.
Prostacyclin and its analogues improve cardiac output and functional capacity in patients with pulmonary arterial hypertension (PAH); however, the underlying mechanism is not fully understood. We hypothesised that prostanoids have load-independent beneficial effects on the right ventricle (RV).
Angio-obliterative PAH and RV failure were induced in rats with a single injection of SU5416 followed by 4 weeks of exposure to hypoxia. Upon confirmation of RV dysfunction and PAH, rats were randomised to 0.1 μg·kg ⁻¹ nebulised iloprost or drug-free vehicle, three times daily for 2 weeks. RV function and treadmill running time were evaluated pre- and post-iloprost/vehicle treatment. Pulmonary artery banded rats were treated 8 weeks after surgery to allow for significant RV hypertrophy.
Inhaled iloprost significantly improved tricuspid annulus plane systolic excursion and increased exercise capacity, while mean pulmonary artery pressure and the percentage of occluded pulmonary vessels remained unchanged. Rats treated with iloprost had a striking reduction in RV collagen deposition, procollagen mRNA levels and connective tissue growth factor expression in both SU5416/hypoxia and pulmonary artery banded rats. In vitro , cardiac fibroblasts treated with iloprost showed a reduction in transforming growth factor (TGF)-β1-induced connective tissue growth factor expression, in a protein kinase A-dependent manner. Iloprost decreased TGF-β1-induced procollagen mRNA expression as well as cardiac fibroblast activation and migration. Iloprost significantly induced metalloproteinase-9 gene expression and activity and increased the expression of autophagy genes associated with collagen degradation.
Inhaled iloprost improves RV function and reverses established RV fibrosis partially by preventing collagen synthesis and by increasing collagen turnover.