miR-21 promotes fibrosis in an acute cardiac allograft transplantation model

The Regulation of MicroRNA-21 by Interleukin-6 and Its Role in the Development of Fibrosis in Endometriotic Lesions

Endometriosis is one of the most common causes of chronic pelvic pain and infertility that affects 10% of women of reproductive age. It is currently defined as the presence of endometrial epithelial and stromal cells at ectopic sites; however, advances in endometriosis research have some authors believing that endometriosis should be re-defined as "a fibrotic condition in which endometrial stroma and epithelium can be identified". microRNAs (miRNAs) are regulatory molecules that potentially play a role in endometriotic lesion development. There is evidence that suggests that miRNAs, including microRNA-21 (miR-21), participate in fibrotic processes in different organs, including the heart, kidney, liver and lungs. The objective of this study was to understand the role of miR-21 and the mechanisms that can contribute to the development of fibrosis by determining how IL-6 regulates miR-21 expression and how this miRNA regulates the transforming growth factor beta (TGF-β) signaling pathway to promote fibrosis. We investigated the expression of miR-21 in the baboon and mouse model of endometriosis and its correlation with fibrosis. We demonstrated that inflammation and fibrosis are present at a very early stage of endometriosis and that the inflammatory environment in the peritoneal cavity, which includes interleukin 6 (IL-6), can regulate the expression of miR-21 in vitro and in vivo.

miR-135a Regulates Atrial Fibrillation by Targeting Smad3

Background

Atrial fibrillation (AF) is the most common arrhythmia in clinical. Atrial fibrosis is a hallmark feature of atrial structural remodeling in AF, which is regulated by the TGF-β1/Smad3 pathway. Recent studies have implicated that miRNAs are involved in the process of AF. However, the regulatory mechanisms of miRNAs remain largely unknown. This study is aimed at investigating the function and regulatory network of miR-135a in AF.

Methods

In vivo, the plasma was collected from patients with AF and non-AF subjects. Adult SD rats were induced by acetylcholine (ACh) (66 μg/ml)-CaCl₂ (10 mg/ml) to establish an AF rat model. In vitro, atrial fibroblasts (AFs), isolated from adult SD rats, were treated with high-frequency electrical stimulation (HES) (12 h) and hypoxia (24 h) to mimic the AF and atrial fibrosis, respectively. miR-135a expression was detected through quantitative real-time polymerase chain reaction (qRT-PCR). The association between miR-135a and Smad3 was speculated by the TargetScan database and confirmed by the luciferase reporter assay. Fibrosis-related genes, Smad3, and TRPM7 were all assessed.

Results

The expression of miR-135a was markedly decreased in the plasma of AF patients and AF rats, which was consistent with that in HES-treated and hypoxia-treated AFs. Smad3 was identified as a target of miR-135a. the downregulation of miR-135a was associated with the enhancement of Smad3/TRPM7 expressions in AFs. Additionally, the knockdown of Smad3 significantly reduced the expression of TRPM7 and further inhibited atrial fibrosis.

Conclusions

Our study demonstrates that miR-135a regulates AF via Smad3/TRPM7, which is a potential therapeutic target for AF.

miR-96-5p regulates myocardial infarction-induced cardiac fibrosis via Smad7/Smad3 pathway

Fibrotic remodelling contributes to heart failure in myocardial infarction. MicroRNAs (miRNAs) play a crucial role in myocardial fibrosis. However, current antifibrotic therapeutic strategies using miRNAs are far from effective. In this study, we aim to investigate the effect of miR-96-5p on cardiac fibrosis. Our work reveals a significant upregulation of miR-96-5p level in the ventricular tissues of myocardial infarction mice, as well as in neonatal rat cardiac fibroblasts stimulated with TGF-β or Ang II as shown by qPCR assay. In myocardial infarction mice, miR-96-5p knockdown using antagomir alleviates the aggravated cardiac fibrosis and exacerbated myocardial function caused by myocardial infarction surgery as shown by the echocardiography and Masson's staining analysis. In contrast, immunofluorescence staining results reveal that miR-96-5p overexpression in neonatal rat cardiac fibroblasts contributes to an increase in the expressions of fibrosis-associated genes and promotes the proliferation and differentiation of cardiac fibroblasts. Conversely, miR-96-5p downregulation using inhibitor presents adverse consequences. Furthermore, Smad7 expression is downregulated in fibrotic cardiac tissues, and the Smad7 gene is identified as a direct target of miR-96-5p by dual luciferase assay. Indeed, Smad7 knockdown weakens the anti-fibrotic effect of the miR-96-5p inhibitor on cardiac fibroblasts. Moreover, Smad3 phosphorylation is elevated in fibrotic cardiac tissues, and interestingly, the Smad3 inhibitor suppresses the profibrotic effect of the miR-96-5p mimic. Taken together, our findings demonstrate that the Smad7/Smad3 signaling pathway mediates the profibrotic effect of miR-96-5p in cardiac fibrosis.

Molecular Approaches and Echocardiographic Deformation Imaging in Detecting Myocardial Fibrosis

The pathological remodeling of myocardial tissue is the main cause of heart diseases. Several processes are involved in the onset of heart failure, and the comprehension of the mechanisms underlying the pathological phenotype deserves special attention to find novel procedures to identify the site of injury and develop novel strategies, as well as molecular druggable pathways, to counteract the high degree of morbidity associated with it. Myocardial fibrosis (MF) is recognized as a critical trigger for disruption of heart functionality due to the excessive accumulation of extracellular matrix proteins, in response to an injury. Its diagnosis remains focalized on invasive techniques, such as endomyocardial biopsy (EMB), or may be noninvasively detected by cardiac magnetic resonance imaging (CMRI). The detection of MF by non-canonical markers remains a challenge in clinical practice. During the last two decades, two-dimensional (2D) speckle tracking echocardiography (STE) has emerged as a new non-invasive imaging modality, able to detect myocardial tissue abnormalities without specifying the causes of the underlying histopathological changes. In this review, we highlighted the clinical utility of 2D-STE deformation imaging for tissue characterization, and its main technical limitations and criticisms. Moreover, we focalized on the importance of coupling 2D-STE examination with the molecular approaches in the clinical decision-making processes, in particular when the 2D-STE does not reflect myocardial dysfunction directly. We also attempted to examine the roles of epigenetic markers of MF and hypothesized microRNA-based mechanisms aiming to understand how they match with the clinical utility of echocardiographic deformation imaging for tissue characterization and MF assessment.

MicroRNAs in kidney injury and disease

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression by degrading or repressing the translation of their target messenger RNAs. As miRNAs are critical regulators of cellular homeostasis, their dysregulation is a crucial component of cell and organ injury. A substantial body of evidence indicates that miRNAs are involved in the pathophysiology of acute kidney injury (AKI), chronic kidney disease and allograft damage. Different subsets of miRNAs are dysregulated during AKI, chronic kidney disease and allograft rejection, which could reflect differences in the physiopathology of these conditions. miRNAs that have been investigated in AKI include miR-21, which has an anti-apoptotic role, and miR-214 and miR-668, which regulate mitochondrial dynamics. Various miRNAs are downregulated in diabetic kidney disease, including the miR-30 family and miR-146a, which protect against inflammation and fibrosis. Other miRNAs such as miR-193 and miR-92a induce podocyte dedifferentiation in glomerulonephritis. In transplantation, miRNAs have been implicated in allograft rejection and injury. Further work is needed to identify and validate miRNAs as biomarkers of graft function and of kidney disease development and progression. Use of combinations of miRNAs together with other molecular markers could potentially improve diagnostic or predictive power and facilitate clinical translation. In addition, targeting specific miRNAs at different stages of disease could be a promising therapeutic strategy.

Non-coding RNAs: Important participants in cardiac fibrosis

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.

Reciprocal organ interactions during heart failure: a position paper from the ESC Working Group on Myocardial Function

Heart failure-either with reduced or preserved ejection fraction (HFrEF/HFpEF)-is a clinical syndrome of multifactorial and gender-dependent aetiology, indicating the insufficiency of the heart to pump blood adequately to maintain blood flow to meet the body's needs. Typical symptoms commonly include shortness of breath, excessive fatigue with impaired exercise capacity, and peripheral oedema, thereby alluding to the fact that heart failure is a syndrome that affects multiple organ systems. Patients suffering from progressed heart failure have a very limited life expectancy, lower than that of numerous cancer types. In this position paper, we provide an overview regarding interactions between the heart and other organ systems, the clinical evidence, underlying mechanisms, potential available or yet-to-establish animal models to study such interactions and finally discuss potential new drug interventions to be developed in the future. Our working group suggests that more experimental research is required to understand the individual molecular mechanisms underlying heart failure and reinforces the urgency for tailored therapeutic interventions that target not only the heart but also other related affected organ systems to effectively treat heart failure as a clinical syndrome that affects and involves multiple organs.

Arteriovenous Fistula-induced Cardiac Remodeling Shows Cardioprotective Features in Mice

Objective

Arteriovenous fistulae (AVF) placed for hemodialysis have high flow rates that can stimulate left ventricular (LV) hypertrophy. LV hypertrophy generally portends poor cardiac outcomes, yet clinical studies point to superior cardiac-specific outcomes for patients with AVF when compared with other dialysis modalities. We hypothesize that AVF induce physiologic cardiac hypertrophy with cardioprotective features.

Methods

We treated 9- to 11-week-old C57Bl/6 male and female mice with sham laparotomy or an aortocaval fistula via a 25G needle. Cardiac chamber size and function were assessed with serial echocardiography, and cardiac computed tomography angiography. Hearts were harvested at 5 weeks postoperatively, and the collagen content was assessed with Masson's trichrome. Bulk messenger RNA sequencing was performed from LV of sham and AVF mice at 10 days. Differentially expressed genes were analyzed using Ingenuity Pathway Analysis (Qiagen) to identify affected pathways and predict downstream biological effects.

Results

Mice with AVF had similar body weight and wet lung mass, but increased cardiac mass compared with sham-operated mice. AVF increased cardiac output while preserving LV systolic and diastolic function, as well as indices of right heart function; all four cardiac chambers were enlarged, with a slight decrement in the relative LV wall thickness. Histology showed preserved collagen density within each of the four chambers without areas of fibrosis. RNA sequencing captured 19 384 genes, of which 857 were significantly differentially expressed, including transcripts from extracellular matrix-related genes, ion channels, metabolism, and cardiac fetal genes. The top upstream regulatory molecules predicted include activation of angiogenic (Vegf, Akt1), procardiomyocyte survival (Hgf, Foxm1, Erbb2, Lin9, Areg), and inflammation-related (CSF2, Tgfb1, TNF, Ifng, Ccr2, IL6) genes, as well as the inactivation of cardiomyocyte antiproliferative factors (Cdkn1a, FoxO3, α-catenin). The predicted downstream effects include a decrease in heart damage, and increased arrhythmia, angiogenesis, and cardiogenesis. There were no significant sex-dependent differences in the AVF-stimulated cardiac adaptation.

Conclusions

AVF stimulate adaptive cardiac hypertrophy in wild-type mice without heart failure or pathologic fibrosis. Transcriptional correlates suggest AVF-induced cardiac remodeling has some cardioprotective, although also arrhythmogenic features. (JVS–Vascular Science 2021;2:110-28.)

Clinical Relevance

Arteriovenous fistulae (AVF) are commonly used as access for hemodialysis in patients with end-stage renal disease. AVF induce a high-output state that is associated with long-term structural cardiac remodeling, including left ventricle hypertrophy, but this element has uncertain clinical significance. Although left ventricle hypertrophy has traditionally been associated with an increased risk of cardiovascular disease, clinical studies have suggested that cardiac-specific outcomes of patients with end-stage renal disease were better with AVF compared with other dialysis modalities. This study uses a mouse model of AVF to study the structural, functional, and molecular correlates of AVF-induced cardiac remodeling. It finds that AVF causes an adaptive cardiac hypertrophy without functional decline or fibrosis. Transcriptional correlates suggest an electrical remodeling and the upregulation of proangiogenic, procardiogenic, and prosurvival factors, implying that AVF-induced cardiac hypertrophy is potentially cardioprotective, but also arrhythmogenic.

MicroRNAs as theranostic markers in cardiac allograft transplantation: from murine models to clinical practice

Congestive heart failure affects about 23 million people worldwide, and cardiac allograft transplantation remains one of the last options for patients with terminal refractory heart failure. Besides the infectious or oncological complications, the prognosis of patients after heart transplantation is affected by acute cellular or antibody-mediated rejection and allograft vasculopathy development. Current monitoring of both conditions requires the performance of invasive procedures (endomyocardial biopsy sampling and coronary angiography or optical coherence tomography, respectively) that are costly, time-demanding, and non-comfortable for the patient. Within this narrative review, we focus on the potential pathophysiological and clinical roles of microRNAs (miRNAs, miRs) in the field of cardiac allograft transplantation. Firstly, we provide a general introduction about the status of cardiac allograft function monitoring and the discovery of miRNAs as post-transcriptional regulators of gene expression and clinically relevant biomarkers found in the extracellular fluid. After this general introduction, information from animal and human studies are summarized to underline the importance of miRNAs both in the pathophysiology of the rejection process, the possibility of its modulation by altering miRNAs levels, and last but not least, about the use of miRNAs in the clinical practice to diagnose or predict the rejection occurrence.

Artemisinin Attenuates Transplant Rejection by Inhibiting Multiple Lymphocytes and Prolongs Cardiac Allograft Survival

Immunological rejection is an important factor resulting in allograft dysfunction, and more valid therapeutic methods need to be explored to improve allograft outcomes. Many researches have indicated that artemisinin and its derivative exhibits immunosuppressive functions, apart from serving as a traditional anti-malarial drug. In this assay, we further explored the therapeutic effects of artemisinin for transplant rejection in a rat cardiac transplantation model. We found that it markedly attenuated allograft rejection and histological injury and significantly prolonged the survival of allograft. Upon further exploring the mechanism, we demonstrated that artemisinin not only attenuated T cell-mediated rejection (TCMR) by reducing effector T cell infiltration and inflammatory cytokine secretion and increasing regulatory T cell infiltration and immunoregulatory cytokine levels, but also attenuated antibody-mediated rejection (ABMR) through inhibition of B cells activation and antibody production. Furthermore, artemisinin also reduced macrophage infiltration in allografts, which was determined to be important for TCMR and ABMR. Moreover, we demonstrated that artemisinin significantly inhibited the function of pure T cells, B cells, and macrophages in vitro. All in all, this study provide evidence that artemisinin significantly attenuates TCMR and ABMR by targeting multiple effectors. Therefore, this agent might have potential for use in clinical settings to protect against transplant rejection.

Cell type-specific microRNA therapies for myocardial infarction

Current interventions fail to recover injured myocardium after infarction and prompt the need for development of cardioprotective strategies. Of increasing interest is the therapeutic use of microRNAs to control gene expression through specific targeting of mRNAs. In this Review, we discuss current microRNA-based therapeutic strategies, describing the outcomes and limitations of key microRNAs with a focus on target cell types and molecular pathways. Last, we offer a perspective on the outlook of microRNA therapies for myocardial infarction, highlighting the outstanding challenges and emerging strategies.

Combined high-throughput library screening and next generation RNA sequencing uncover microRNAs controlling human cardiac fibroblast biology

BACKGROUND

Myocardial fibrosis is a hallmark of the failing heart, contributing to the most common causes of deaths worldwide. Several microRNAs (miRNAs, miRs) controlling cardiac fibrosis were identified in recent years; however, a more global approach to identify miRNAs involved in fibrosis is missing.

METHODS AND RESULTS

Functional miRNA mimic library screens were applied in human cardiac fibroblasts (HCFs) to identify annotated miRNAs inducing proliferation. In parallel, miRNA deep sequencing was performed after subjecting HCFs to proliferating and resting stimuli, additionally enabling discovery of novel miRNAs. In-depth in vitro analysis confirmed the pro-fibrotic nature of selected, highly conserved miRNAs miR-20a-5p and miR-132-3p. To determine downstream cellular pathways and their role in the fibrotic response, targets of the annotated miRNA candidates were modulated by synthetic siRNA. We here provide evidence that repression of autophagy and detoxification of reactive oxygen species by miR-20a-5p and miR-132-3p explain some of their pro-fibrotic nature on a mechanistic level.

CONCLUSION

We here identified both miR-20a-5p and miR-132-3p as crucial regulators of fibrotic pathways in an in vitro model of human cardiac fibroblast biology.

Role of IgE-FcεR1 in Pathological Cardiac Remodeling and Dysfunction

BACKGROUND

Immunoglobulin E (IgE) belongs to a class of immunoglobulins involved in immune response to specific allergens. However, the roles of IgE and IgE receptor (FcεR1) in pathological cardiac remodeling and heart failure are unknown.

METHODS

Serum IgE levels and cardiac FcεR1 expression were assessed in diseased hearts from human and mouse. The role of FcεR1 signaling in pathological cardiac remodeling was explored in vivo by FcεR1 genetic depletion, anti-IgE antibodies, and bone marrow transplantation. The roles of the IgE-FcεR1 pathway were further evaluated in vitro in primary cultured rat cardiomyocytes and cardiac fibroblasts (CFs). RNA sequencing and bioinformatic analyses were used to identify biochemical changes and signaling pathways that are regulated by IgE/FcεR1.

RESULTS

Serum IgE levels were significantly elevated in patients with heart failure as well as in 2 mouse cardiac disease models induced by chronic pressure overload via transverse aortic constriction and chronic angiotensin II infusion. Interestingly, FcεR1 expression levels were also significantly upregulated in failing hearts from human and mouse. Blockade of the IgE-FcεR1 pathway by FcεR1 knockout alleviated transverse aortic constriction- or angiotensin II-induced pathological cardiac remodeling or dysfunction. Anti-IgE antibodies (including the clinical drug omalizumab) also significantly alleviated angiotensin II-induced cardiac remodeling. Bone marrow transplantation experiments indicated that IgE-induced cardiac remodeling was mediated through non-bone marrow-derived cells. FcεR1 was found to be expressed in both cardiomyocytes and CFs. In cultured rat cardiomyocytes, IgE-induced cardiomyocyte hypertrophy and hypertrophic marker expression were abolished by depleting FcεR1. In cultured rat CFs, IgE-induced CF activation and matrix protein production were also blocked by FcεR1 deficiency. RNA sequencing and signaling pathway analyses revealed that transforming growth factor-β may be a critical mediator, and blocking transforming growth factor-β indeed alleviated IgE-induced cardiomyocyte hypertrophy and cardiac fibroblast activation in vitro.

CONCLUSIONS

Our findings suggest that IgE induction plays a causative role in pathological cardiac remodeling, at least partially via the activation of IgE-FcεR1 signaling in cardiomyocytes and CFs. Therapeutic strategies targeting the IgE-FcεR1 axis may be effective for managing IgE-mediated cardiac remodeling.

Aging, MicroRNAs, and Heart Failure

Aging is a major risk factor for heart failure, one of the leading causes of death in Western society. The mechanisms that underlie the different forms of heart failure have been elucidated only in part and the role of noncoding RNAs is still poorly characterized. Specifically, microRNAs (miRNAs), a class of small noncoding RNAs that can modulate gene expression at the posttranscriptional level in all cells, including myocardial and vascular cells, have been shown to play a role in heart failure with reduced ejection fraction. In contrast, miRNAs role in heart failure with preserved ejection fraction, the predominant form of heart failure in the elderly, is still unknown. In this review, we will focus on age-dependent miRNAs in heart failure and on some other conditions that are prevalent in the elderly and are frequently associated with heart failure with preserved ejection fraction.

Roles of Biomarkers in Myocardial Fibrosis

Myocardial fibrosis is observed in various cardiovascular diseases and plays a key role in the impairment of cardiac function. Endomyocardial biopsy, as the gold standard for the diagnosis of myocardial fibrosis, has limitations in terms of clinical application. Therefore, biomarkers have been recommended for noninvasive assessment of myocardial fibrosis. This review discusses the role of biomarkers in myocardial fibrosis from the perspective of collagen.

Function analysis of differentially expressed microRNAs in TGF-β1-induced cardiac fibroblasts differentiation

BACKGROUND

Cardiac fibroblasts differentiation plays a critical role in cardiac remodeling and failure, but the underlying molecular mechanisms are still poorly understood. MicroRNAs (miRNAs) had been identified as important regulators during cell differentiation. The aim of the present study was to screen the miRNAs involved in regulation of cardiac fibroblasts differentiation.

METHODS

The differentiation of rat cardiac fibroblasts into myofibroblasts was induced by transforming growth factor-β1 (TGF-β1). Small RNA sequencing was then applied to detect the differentially expressed miRNAs.

RESULTS

A total of 450 known miRNAs were detected, and 127 putative novel miRNAs were predicted by miRDeep2 analysis. DEGseq analysis and qRT-PCR confirmed that 24 known miRNAs were differentially expressed in TGF-β1-induced cardiac fibroblasts, including three up-regulated miRNAs and 21 down-regulated miRNAs. After miRNAs target genes prediction by miRanda algorithm, pathway analysis showed that these potential target genes were involved in Calcium signaling pathway, Type II diabetes mellitus, and Glutamatergic synapse pathway, etc. Meanwhile, seven putative miRNAs were also detected differentially expressed during TGF-β1-induced cardiac fibroblasts differentiation.

CONCLUSIONS

These differentially expressed miRNAs might play critical roles in cardiac fibroblasts differentiation. Altered expression of miRNAs may yield new insights into the underlying mechanisms of cardiac fibrosis and provide novel mechanism-based therapeutic strategies for cardiac fibrosis.

Ultrasonic cardiogram and MiRNA-21 analysis of cardiac dysfunction in patients with cardiac arrest following cardiopulmonary resuscitation

PURPOSE

To explore correlations between the serum level of miRNA-21 expression and cardiac dysfunction severity after cardiopulmonary resuscitation (CPR) using ultrasonic cardiogram.

METHODS

Thirty-nine patients with cardiopulmonary arrest receiving successful CPR and forty-one healthy participants were recruited in the study. Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and immunochemiluminometric assays was used to examine the serum miRNA-21 level and the concentration of cardiac troponins T and I, respectively. Indices of Electrocardiogram (ECG) and cardiac dysfunction measured by ultrasound of patients in the case group were used to assess cardiac function after CPR. Furthermore, the correlation between the serum level of miRNA-21 expression and severity of cardiac dysfunction was analyzed by Spearman correlation analysis.

RESULTS

As compared to the control group, the serum level of miRNA-21 expression, as well as cardiac troponin T and I levels in the case group were significantly higher (p = 0.000). The miRNA-21 expression level in the patients at IV grade of cardiac function were substantially higher than patients at III grade (p = 0.015). There was no significant difference in level of cardiac troponins T and I between patients at III grade and patients at IV grade (p > 0.05). Further, Spearman correlation analysis revealed that the level of miRNA-21 expression was negatively correlated with cardiac function index in the ultrasound imaging: E peak, E/A value, LVEF and LVEDD (r = 0.617, 0.535, 0.612, 0.573, P = 0.012, 0.009, 0.008, 0.011), but was positively correlated with the level of cardiac troponins T and I (r = 0.546,0.582, P = 0.006,0.007) and the severity of cardiac dysfunction (r = 0.859, p < 0.05).

CONCLUSION

The level of miRNA-21 is higher after CPR is closely related to the severity of cardiac dysfunction that is measured by ultrasound, suggesting that it may serve as a potential biomarker.

An Overview of Non-coding RNAs and Cardiovascular System

Cardiovascular disease management and timely diagnosis remain a major dilemma. Delineating molecular mechanisms of cardiovascular diseases is opening horizon in the field of molecular medicines and in the development of early diagnostic markers. Non-coding RNAs are the highly functional and vibrant nucleic acids and are known to be involved in the regulation of endothelial cells, vascular and smooth muscles cells, cardiac metabolism, ischemia, inflammation and many processes in cardiovascular system. This chapter is comprehensively focusing on the overview of the non-coding RNAs including their discovery, generation, classification and functional regulation. In addition, overview regarding different non-coding RNAs as long non-coding, siRNAs and miRNAs involvement in the cardiovascular diseases is also addressed. Detailed functional analysis of this vast group of highly regulatory molecules will be promising for shaping future drug discoveries.

MicroRNA-142-5p is Up-regulated on Allogeneic Immune Responses and Up-regulates MHC Class II Expression in Human Umbilical Vein Endothelial Cells

PURPOSE

MicroRNA could be biomarker and therapeutic target for rejection. The aim of this study was to investigate the role of miR-142-5p in allogeneic immune responses using in vitro and in vivo models.

MATERIALS AND METHODS

Primary and immortalized human umbilical vein endothelial cells (HUVECs) were cultured with unrelated blood mononuclear cells to induce allogeneic immune responses. Syngeneic and allogeneic skin graft was performed in mice. Flow cytometry, quantitative reverse transcription-polymerase chain reaction, and Western blotting was performed to understand the underlying mechanisms.

RESULTS

miR-142-5p was up-regulated in primary HUVEC and a HUVEC line when allogeneic immune responses were elicited. miR-142-5p was also up-regulated in the murine allogeneic skin graft. Overexpression of miR-142-5p in HUVEC increased the expression of HLA-ABC and HLA-DR additively to allogeneic immune responses, suggesting a possible increase in alloantigen presentation. Inhibition of miR-142-5p reduced the expression of HLA-DR. ZEB1, a putative target gene of miR-142-5p, was down-regulated in HUVEC on allogeneic immune response as well as in murine allogeneic skin graft.

CONCLUSION

These results suggest that the up-regulation of miR-142-5p on allogeneic immune response might facilitate endothelial activation to exacerbate rejection.

Long non-coding RNA X-inactive specific transcript silencing ameliorates primary graft dysfunction following lung transplantation through microRNA-21-dependent mechanism

Background

Primary graft dysfunction (PGD) is a known acute lung injury (ALI) and a major cause of fatality post-lung transplantation. Though some long non-coding RNAs (lncRNAs) have been studied in ALI through regulation of microRNAs (miRNAs), their effects on PGD remain undefined. The present study aims to explore the underlying mechanism of lncRNA X-inactive specific transcript (XIST) in PGD after lung transplantation.

Methods

Initially, the expression of miR-21, IL-12A and XIST was determined by RT-qPCR and western blot analysis. The dual luciferase reporter assay, RNA pull-down and RIP assay were performed to identify the targeting relationship between miR-21 and IL-12A and the binding relationship between miR-21 and XIST. Loss- and gain-of-function investigations were conducted in rats treated with prolonged cold ischemia and polymorphonuclear neutrophils (PMNs).

Findings

miR-21 was decreased, whilst XIST and IL-12A were increased in the bronchoalveolar lavage fluid of PGD patients after lung transplantation. Enhanced miR-21 expression in rats and PMNs resulted in downregulated expression of pro-inflammatory factors and chemokines, and enhanced the apoptosis of PMNs. XIST was found to upregulate IL-12A expression in a miR-21-dependent manner. Additionally, XIST silencing enhanced the apoptosis of PMNs and inhibited the neutrophil extracellular trap (NET) formation through upregulation of miR-21 but downregulation of IL-12A in vivo.

Interpretation

In summary, lncRNA XIST upregulates IL-12A by binding to miR-21, thereby inducing NET formation and accelerating PGD after lung transplantation. This suggests that inhibition of XIST and NET may be beneficial for the treatment of PGD.

Deficiency of MicroRNA miR-1954 Promotes Cardiac Remodeling and Fibrosis

Background Cardiac fibrosis occurs because of disruption of the extracellular matrix network leading to myocardial dysfunction. Angiotensin II (AngII) has been implicated in the development of cardiac fibrosis. Recently, microRNAs have been identified as an attractive target for therapeutic intervention in cardiac pathologies; however, the underlying mechanism of microRNAs in cardiac fibrosis remains unclear. Next-generation sequencing analysis identified a novel characterized microRNA, miR-1954, that was significantly reduced in AngII-infused mice. The finding led us to hypothesize that deficiency of miR-1954 triggers cardiac fibrosis. Methods and Results A transgenic mouse was created using α-MHC (α-myosin heavy chain) promoter and was challenged with AngII infusion. AngII induced cardiac hypertrophy and remodeling. The in vivo overexpression of miR-1954 showed significant reduction in cardiac mass and blood pressure in AngII-infused mice. Further analysis showed significant reduction in cardiac fibrotic genes, hypertrophy marker genes, and an inflammatory gene and restoration of a calcium-regulated gene (Atp2a2 [ATPase sarcoplasmic/endoplasmic reticulum Ca2+ transporting 2]; also known as SERCA2), but no changes were observed in apoptotic genes. THBS1 (thrombospondin 1) is indicated as a target gene for miR-1954. Conclusions Our findings provide evidence, for the first time, that miR-1954 plays a critical role in cardiac fibrosis by targeting THBS1. We conclude that promoting the level of miR-1954 would be a promising strategy for the treatment of cardiac fibrosis.

IL-6 trans-signalling contributes to aldosterone-induced cardiac fibrosis

Aims

An excess of aldosterone results in cardiac remodelling and fibrosis. Interleukin-6 (IL-6) is a key mediator in the fibrotic process; however, the effect of aldosterone on the expression of IL-6 remains unclear. We investigated whether aldosterone induces the expression of IL-6 and thereby contributes to the fibrotic process.

Methods and results

In this clinical study, we prospectively enrolled 25 patients with primary aldosteronism (PA) and 26 patients with essential hypertension (EH). The PA patients had higher plasma IL-6 levels, left ventricular mass index, degree of myocardial fibrosis, and more impaired diastolic function than the EH patients. In addition, plasma IL-6 levels were positively correlated with 24-h urinary aldosterone and echocardiographic parameters. In cell studies, we investigated the possible molecular mechanism how aldosterone-induced IL-6 secretion and the further effects of collagen production. Aldosterone significantly induced IL-6 protein and mRNA production in human umbilical vein endothelial cells. Intracellular signalling occurred through the mineralocorticoid receptor/PI3K/Akt/NF-kB pathway. In cardiac fibroblasts, IL-6 trans-signalling played a critical role in aldosterone-induced IL-6-enhanced fibrosis-related factor expression. To further investigate the role of IL-6 trans-signalling in aldosterone-induced cardiac fibrosis, we measured the severity of myocardial fibrosis in aldosterone infusion mice models including an IL-6 chemical inhibitor and Sgp130 Knockin Transgenic Mice. Mice receiving recombinant soluble gp130 and Sgp130 Knockin Transgenic Mice prevented myocardial fibrosis and cardiac hypertrophy by aldosterone infusion.

Conclusions

IL-6 trans-signalling contributes to aldosterone-induced cardiac fibrosis.

The extracellular matrix proteoglycan lumican improves survival and counteracts cardiac dilatation and failure in mice subjected to pressure overload

Left ventricular (LV) dilatation is a key step in transition to heart failure (HF) in response to pressure overload. Cardiac extracellular matrix (ECM) contains fibrillar collagens and proteoglycans, important for maintaining tissue integrity. Alterations in collagen production and cross-linking are associated with cardiac LV dilatation and HF. Lumican (LUM) is a collagen binding proteoglycan with increased expression in hearts of patients and mice with HF, however, its role in cardiac function remains poorly understood. To examine the role of LUM in pressure overload induced cardiac remodeling, we subjected LUM knock-out (LUMKO) mice to aortic banding (AB) and treated cultured cardiac fibroblasts (CFB) with LUM. LUMKO mice exhibited increased mortality 1-14 days post-AB. Echocardiography revealed increased LV dilatation, altered hypertrophic remodeling and exacerbated contractile dysfunction in surviving LUMKO 1-10w post-AB. LUMKO hearts showed reduced collagen expression and cross-linking post-AB. Transcriptional profiling of LUMKO hearts by RNA sequencing revealed 714 differentially expressed transcripts, with enrichment of cardiotoxicity, ECM and inflammatory pathways. CFB treated with LUM showed increased mRNAs for markers of myofibroblast differentiation, proliferation and expression of ECM molecules important for fibrosis, including collagens and collagen cross-linking enzyme lysyl oxidase. In conclusion, we report the novel finding that lack of LUM attenuates collagen cross-linking in the pressure-overloaded heart, leading to increased mortality, dilatation and contractile dysfunction in mice.

The Winding Road of Cardiac Regeneration-Stem Cell Omics in the Spotlight

Despite significant progress in treating ischemic cardiac disease and succeeding heart failure, there is still an unmet need to develop effective therapeutic strategies given the persistent high-mortality rate. Advances in stem cell biology hold great promise for regenerative medicine, particularly for cardiac regeneration. Various cell types have been used both in preclinical and clinical studies to repair the injured heart, either directly or indirectly. Transplanted cells may act in an autocrine and/or paracrine manner to improve the myocyte survival and migration of remote and/or resident stem cells to the site of injury. Still, the molecular mechanisms regulating cardiac protection and repair are poorly understood. Stem cell fate is directed by multifaceted interactions between genetic, epigenetic, transcriptional, and post-transcriptional mechanisms. Decoding stem cells’ “panomic” data would provide a comprehensive picture of the underlying mechanisms, resulting in patient-tailored therapy. This review offers a critical analysis of omics data in relation to stem cell survival and differentiation. Additionally, the emerging role of stem cell-derived exosomes as “cell-free” therapy is debated. Last but not least, we discuss the challenges to retrieve and analyze the huge amount of publicly available omics data.

MicroRNA-21 contributes to high glucose-induced fibrosis in peritoneal mesothelial cells in rat models by activation of the Ras-MAPK signaling pathway via Sprouty-1

Peritoneal fibrosis remains to be one of the most severe causes of failure in continuous peritoneal dialysis. The current study cultured peritoneal mesothelial cells in high glucose to stimulate the environment of peritoneal fibrosis model in rats, and investigate whether microRNA-21 (miR-21) targeting Sprouty-1 affects high glucose-induced fibrosis in peritoneal mesothelial cells via the rennin angiotensin system (Ras)-mitogen-activated protein kinase (MAPK) signaling pathway, as well as potential mechanisms. Peritoneal tissues in fibrosis rats were collected to extract peritoneal mesothelial cells, which, after in vitro culture, were transfected with a series of mimic or inhibitor of miR-21, or the small interfering RNA (siRNA) against Sprouty-1. Reverse-transcription quantitative polymerase chain reaction and western blot analyses were performed to determine the levels of related genes or proteins. MTT assay and flow cytometry were conducted to observe the cell viability and cell apoptosis of peritoneal mesothelial cells. Dual-luciferase reporter gene assay revealed that Sprouty-1 is the target gene of miR-21. Peritoneal fibrosis manifested with elevated miR-21, extracellular-signal-regulated kinase (ERK), c-Jun NH2-terminal protein kinase (JNK), RAS and p38MAPK but reduced Sprouty-1. Cells transfected with miR-21 mimic exhibited decreased Sprouty-1 expressions, but increased levels of ERK, JNK, RAS, and p38MAPK. As for cellular process, miR-21 mimic or siRNA against Sprouty-1 exposure reduced cell viability, which resulted in more cells arrested at the G1 stage, and induced apoptosis. In contrast, miR-21 inhibitor exposure was observed to have induced effects on peritoneal mesothelial cells. These key findings provide evidence that miR-21 inhibits Sprouty-1 to promote the progression of fibrosis in peritoneal mesothelial cells by activating the Ras-MAPK signaling pathway.

MicroRNA-21 ablation exacerbates aldosterone-mediated cardiac injury, remodeling, and dysfunction

Primary aldosteronism is characterized by excess aldosterone secretion by the adrenal gland independent of the renin-angiotensin system and accounts for ~10% of hypertensive patients. Excess aldosterone causes cardiac hypertrophy, fibrosis, inflammation, and hypertension. The molecular mechanisms that trigger the onset and progression of aldosterone-mediated cardiac injury remain incompletely understood. MicroRNAs (miRNAs) are endogenous, small, noncoding RNAs that have been implicated in multiple cardiac pathologies; however, their regulation and role in aldosterone-mediated cardiac injury and dysfunction remains mostly unknown. We previously reported that microRNA-21 (miR-21) is the most upregulated miRNA by excess aldosterone in the left ventricle in a rat experimental model of primary aldosteronism. To elucidate the role of miR-21 in aldosterone-mediated cardiac injury and dysfunction, miR-21 knockout mice and their wild-type littermates were treated with aldosterone infusion and salt in the drinking water for 2 or 8 wk. miR-21 genetic ablation exacerbated aldosterone/salt-mediated cardiac hypertrophy and cardiomyocyte cross-sectional area. Furthermore, miR-21 genetic ablation increased the cardiac expression of fibrosis and inflammation markers and fetal gene program. miR-21 genetic ablation increased aldosterone/salt-mediated cardiac dysfunction but did not affect aldosterone/salt-mediated hypertension. miR-21 target gene Sprouty 2 may be implicated in the cardiac effects of miR-21 genetic ablation. Our study shows that miR-21 genetic ablation exacerbates aldosterone/salt-mediated cardiac hypertrophy, injury, and dysfunction blood pressure independently. These results suggest that miR-21 plays a protective role in the cardiac pathology triggered by excess aldosterone. Furthermore, miR-21 supplementation may be a novel therapeutic approach to abolish or mitigate excess aldosterone-mediated cardiovascular deleterious effects in primary aldosteronism.

Angiotensin II receptor blocker valsartan ameliorates cardiac fibrosis partly by inhibiting miR-21 expression in diabetic nephropathy mice

Cardiac fibrosis with diabetic nephropathy (DN) is one of major diabetic complications. miR-21 and MMP-9 were closely associated with fibrosis diseases. Angiotensin II receptor blockers (ARB) have cardioprotective effects. However, it remains unclear whether miR-21 was involved in the mechanism of cardiac fibrosis with DN by target MMP-9 and ARB ameliorates cardiac fibrosis partly by inhibiting miR-21 expression. In this study, In Situ Hybridization(ISH), RT-PCR, cell transfection, western blotting and laser confocal telescope were used, respectively. ISH showed that miR-21, concentrated in cytoplasmic foci in the proximity of the nucleus, was mainly localized in cardiac fibroblasts and at relatively low levels in cardiomyocytes within cardiac tissue with DN. RT-PCR showed that miR-21 expression was significantly enhanced in cardiac tissue with DN, accompanied by the increase of col-IV, FN, CVF, PVCA, LVMI, HWI and NT-pro-BNP (p < 0.05). Bioinformatics analysis and Luciferase reporter gene assays showed that MMP-9 was a validated target of miR-21. Furthermore, cell transfection experiments showed that miR-21 overexpression directly decreased MMP-9 expression. Interestingly, miR-21 levels in cardiac tissue was positively correlated with ACR (r = -0.870, P = 0.003), whereas, uncorrelated with SBP, HbA1C and T-Cho (p > 0.05). More importantly, ARB can significantly decrease miR-21 expression in cardiac tissue, cardiac fibroblasts and serum. Overall, our results suggested that miR-21 may contribute to the pathogenesis of cardiac fibrosis with DN by target MMP-9, and that miR-21 may be a new possible therapeutic target for ARB in cardiac fibrosis with DN.

Epigenetics and Immunometabolism in Diabetes and Aging

SIGNIFICANCE

A strong relationship between hyperglycemia, impaired insulin pathway, and cardiovascular disease in type 2 diabetes (T2D) is linked to oxidative stress and inflammation. Immunometabolic pathways link these pathogenic processes and pose important potential therapeutic targets. Recent Advances: The link between immunity and metabolism is bidirectional and includes the role of inflammation in the pathogenesis of metabolic disorders such as T2D, obesity, metabolic syndrome, and hypertension and the role of metabolic factors in regulation of immune cell functions. Low-grade inflammation, oxidative stress, balance between superoxide and nitric oxide, and the infiltration of macrophages, T cells, and B cells in insulin-sensitive tissues lead to metabolic impairment and accelerated aging.

CRITICAL ISSUES

Inflammatory infiltrate and altered immune cell phenotype precede development of metabolic disorders. Inflammatory changes are tightly linked to alterations in metabolic status and energy expenditure and are controlled by epigenetic mechanisms.

FUTURE DIRECTIONS

A better comprehension of these mechanistic insights is of utmost importance to identify novel molecular targets. In this study, we describe a complex scenario of epigenetic changes and immunometabolism linking to diabetes and aging-associated vascular disease. Antioxid. Redox Signal. 29, 257-274.

MicroRNA signatures in cardiac biopsies and detection of allograft rejection

BACKGROUND

Identification of heart transplant (HTx) rejection currently relies on immunohistology and immunohistochemistry. We aimed to identify specific sets of microRNAs (miRNAs) to characterize acute cellular rejection (ACR), antibody-mediated rejection (pAMR), and mixed rejection (MR) in monitoring formalin-fixed paraffin-embedded (FFPE) endomyocardial biopsies (EMBs) in HTx patients.

METHODS

In this study we selected 33 adult HTx patients. For each, we chose the first positive EMB for study of each type of rejection. The next-generation sequencing (NGS) IonProton technique and reverse transcript quantitative polymerase chain reaction (RT-qPCR) analysis were performed on FFPE EMBs. Using logistic regression analysis we created unique miRNA signatures as predictive models of each rejection. In situ PCR was carried out on the same EMBs.

RESULTS

We obtained >2,257 mature miRNAs from all the EMBs. The 3 types of rejection showed a different miRNA profile for each group. The logistic regression model formed by miRNAs 208a, 126-5p, and 135a-5p identified MR; that formed by miRNAs 27b-3p, 29b-3p, and 199a-3p identified ACR; and that formed by miRNAs 208a, 29b-3p, 135a-5p, and 144-3p identified pAMR. The expression of miRNAs on tissue, through in situ PCR, showed different expressions of the same miRNA in different rejections. miRNA 126-5p was expressed in endothelial cells in ACR but in cardiomyocytes in pAMR. In ACR, miRNA 29b-3p was significantly overexpressed and detected in fibroblasts, whereas in pAMR it was underexpressed and detected only in cardiomyocytes.

CONCLUSIONS

miRNA profiling on FFPE EMBs differentiates the 3 types of rejection. Localization of expression of miRNAs on tissue showed different expression of the same miRNA for different cells, suggesting different roles of the same miRNA in different rejections.

Serum MicroRNA Levels as a Noninvasive Diagnostic Biomarker for the Early Diagnosis of Hepatitis B Virus-Related Liver Fibrosis

Background/Aims

To investigate the role of selected serum microRNA (miRNA) levels as potential noninvasive biomarkers for differentiating S0-S2 (early fibrosis) from S3-S4 (late fibrosis) in patients with a chronic hepatitis B virus (HBV) infection.

Methods

One hundred twenty-three treatment-naive patients with a chronic HBV infection who underwent a liver biopsy were enrolled in this study. The levels of selected miRNAs were measured using a real-time quantitative polymerase chain reaction assay. A logistic regression analysis was performed to assess factors associated with fibrosis progression. Receiver operating characteristic (ROC) curve and discriminant analyses validated these the ability of these predicted variables to discriminate S0-S2 from S3-S4.

Results

Serum miR-29, miR-143, miR-223, miR-21, and miR-374 levels were significantly downregulated as fibrosis progressed from S0-S2 to S3-S4 (p<0.05), but not miR-16. The multivariate logistic regression analysis identified a panel of three miRNAs and platelets that were associated with a high diagnostic accuracy in discriminating S0-S2 from S3-S4, with an area under the curve of 0.936.

Conclusions

The levels of the studied miRNAs, with the exception of miR-16, varied with fibrosis progression. A panel was identified that was capable of discriminating S0-S2 from S3-S4, indicating that serum miRNA levels could serve as a potential noninvasive biomarker of fibrosis progression.

Circulating MicroRNAs: a Potential Biomarker for Cardiac Damage, Inflammatory Response, and Left Ventricular Function Recovery in Pediatric Viral Myocarditis

Viral myocarditis (VM) can be a life-threatening event resulting in cardiac failure, chronic cardiomyopathy, and death. VM typically includes three phases, i.e., acute, subacute, and resolution/chronic. We prospectively investigated cardiac- and inflammatory-associated plasma-circulating miRNA levels in eight pediatric patients with VM during the three stages of the disease. The level of cardiac-associated miR-208a was significantly elevated during the acute phase compared with the subacute and resolution/chronic phases. The level of cardiac- and inflammatory-associated miR-21 was significantly elevated during the acute phase compared to the resolution/chronic phase. Moreover, cardiac-associated miR-208b levels during the subacute phase correlated with systolic left ventricular function recovery as measured during the resolution/chronic phase. The findings of our study demonstrate an association between cardiac damage and the inflammatory response and the expression of miR-208a and miR-21 during the pathological progression of myocarditis. We also found that miR-208b levels exhibit a prognostic significance for left ventricular functional recovery.

MicroRNA-21a-5p promotes fibrosis in spinal fibroblasts after mechanical trauma

Traumatic spinal cord injury (SCI) causes permanent disability to at least 180,000 people per year worldwide. Early regulation of spinal fibroblast proliferation may inhibit fibrotic scar formation, allowing the creation of a favorable environment for neuronal regeneration and thereby enhancing recovery from traumatic SCIs. In this study, we aimed to identify the role of microRNA-21a-5p (miR-21a-5p) in regulating spinal fibroblasts after mechanical trauma and to investigate the dysregulation of miR-21a-5p in the pathological process of spinal SCI. We investigated the differential expression of microRNAs in primary spinal fibroblasts after mechanical trauma and found that the expression of miR-21a-5p was higher in spinal fibroblasts after scratch damage (SD). In addition, mouse spinal fibroblasts were transfected with miR-21a-5p mimics/inhibitor, and the role of miR-21a-5p in spinal fibrogenic activation was analyzed. These experiments demonstrated that miR-21a-5p overexpression promoted fibrogenic activity in spinal fibroblasts after mechanical trauma, as well as enhancing proliferation and attenuating apoptosis in spinal fibroblasts. Finally, the potential role of miR-21a-5p in regulating the Smad signaling pathway was examined. MiR-21a-5p activated the Smad signaling pathway by enhancing Smad2/3 phosphorylation. These results suggest that miR-21a-5p promotes spinal fibrosis after mechanical trauma. Based on these findings, we propose a close relationship between miR-21a-5p and spinal fibrosis, providing a new potential therapeutic target for SCI.

Applying genomics in heart transplantation

While advances in patient care and immunosuppressive pharmacotherapies have increased the lifespan of heart allograft recipients, there are still significant comorbidities post-transplantation and 5-year survival rates are still significant, at approximately 70%. The last decade has seen massive strides in genomics and other omics fields, including transcriptomics, with many of these advances now starting to impact heart transplant clinical care. This review summarizes a number of the key advances in genomics which are relevant for heart transplant outcomes, and we highlight the translational potential that such knowledge may bring to patient care within the next decade.

miR-21 suppression prevents cardiac alterations induced by d-galactose and doxorubicin

d-galactose (d-gal)-induced cardiac alterations and Doxorubicin (Dox)-induced cardiomyocyte senescence are commonly used models to study cardiac aging. Accumulating evidence has suggested that microRNAs (miRNAs, miRs) are critically involved in the regulation of cellular and organismal aging and age-related diseases. However, little has been revealed about the roles of miRNAs in cardiac alterations induced by d-gal and Dox. In this study, we used miRNA arrays to investigate the dysregulated miRNAs in heart samples from 15month-old versus 2month-old male C57BL/6 mice and further validated them in d-gal-induced pseudo-aging mouse model and Dox-induced cardiomyocyte senescence in vitro model. We confirmed a significant increase of miR-21 in all these models by quantitative reverse transcription polymerase chain reactions. We further demonstrated that miR-21 was able to promote Dox-induced cardiomyocyte senescence whereas suppression of miR-21 could prevent that, as determined by percentage of β-gal-positive cells and gene markers of aging. Phosphatase and tensin homolog (PTEN) was identified as a target gene of miR-21, mediating its effect in increasing cardiomyocyte senescence. Finally, we found that miR-21 knockout mice were resistant to d-gal-induced alterations in aging-markers and cardiac function. Collectively, this study provides direct evidence that inhibition of miR-21 is protective against d-gal-induced cardiac alterations and Dox-induced cardiomyocyte senescence via targeting PTEN. Inhibition of miR-21 might be a novel strategy to combat cardiac aging.

LncRNA COL1A2-AS1 inhibits the scar fibroblasts proliferation via regulating miR-21/Smad7 pathway

lncRNA COL1A2-AS1 (COL1A2 antisense RNA 1), a lncRNA overexpressed in hypertrophic scar, has been demonstrated to be involved in the hypertrophic scar formation. However, the mechanisms of lncRNA COL1A2-AS1 inhibiting the scar fibroblasts proliferation remains not well understood. In this study, we demonstrated that lncRNA COL1A2-AS1 was upregulated in hypertrophic scar tissue and fibroblasts, and suppressed fibroblasts proliferation by promoting Smad7 expression. Furthermore, we found that miR-21 was involved in lncRNA COL1A2-AS1-induced expression of Smad7, by which COL1A2-AS1 acted as endogenous sponge to adsorb miR-21 and in turn regulated Smad7 and a cascade of molecular to play a protective role in hypertrophic scar. In addition, overexpression of miR-21 attenuated COL1A2-AS1-mediated proliferation suppression of hypertrophic scar fibroblasts. In conclusion, our study demonstrated that COL1A2-AS1/miR-21/Smad pathway plays an important role in inhibiting hypertrophic scar formation, and suggested this novel pathway may be a new target for hypertrophic scar treatment.

Biomarkers in patients with myocardial fibrosis

Myocardial fibrosis is observed in many cardiovascular diseases including hypertension, heart failure and cardiomyopathy. Myocardial fibrosis has been proved to be reversible and treatable only under timely intervention, which makes early detection and assessment of fibrosis crucial. Aside from tissue biopsy as the gold standard for the diagnosis of myocardial fibrosis, circulating biomarkers have been adopted as noninvasive assessment of this lesion. Dysregulated collagen deposition is thought to be the major cause of myocardial fibrosis. Collagens, procollagens, TGF-β, TIMP, galectin-3, and microRNAs are thought to be indicators of myocardial fibrosis. In this review, we summarize the molecules that are frequently used as biomarkers in diagnosis of cardiac fibrosis. Mechanisms of fibrosis that they take part in are also introduced.

The epigenetic promise to improve prognosis of heart failure and heart transplantation

Heart transplantation is still the only possible life-saving treatment for end-stage heart failure, the critical epilogue of several cardiac diseases. Epigenetic mechanisms are being intensively investigated because they could contribute to establishing innovative diagnostic and predictive biomarkers, as well as ground-breaking therapies both for heart failure and heart transplantation rejection. DNA methylation and histone modifications can modulate the innate and adaptive immune response by acting on the expression of immune-related genes that, in turn, are crucial determinants of transplantation outcome. Epigenetic drugs acting on methylation and histone-modification pathways may modulate Treg activity by acting as immunosuppressive agents. Moreover, the identification of non-invasive and reliable epigenetic biomarkers for the prediction of allograft rejection and for monitoring immunosuppressive therapies represents an attractive perspective in the management of transplanted patients. MiRNAs seem to fit particularly well to this purpose because they are differently expressed in patients at high and low risk of rejection and are detectable in biological fluids besides biopsies. Although increasing evidence supports the involvement of epigenetic tags in heart failure and transplantation, further short and long-term clinical studies are needed to translate the possible available findings into clinical setting.

Tacrolimus induces fibroblasts apoptosis and reduces epidural fibrosis by regulating miR-429 and its target of RhoE

Tacrolimus (FK506) has been demonstrated to reduce epidural fibrosis. However, the detailed mechanism of action has not been elucidated. Aberrant miR-429 is involved in many diseases. The aim of this study was to describe the exact mechanism of FK506 induced apoptosis in fibroblasts and the prevention of epidural fibrosis. FK506 induced fibroblast apoptosis was evaluated using CCK-8 assays, flow cytometry, and western blotting. The expression of miR-429 in fibroblasts treated with FK506 was determined by RT-qPCR. Additionally, luciferase activity assays were used to determine the target relationship between miR-429 and RhoE. Flow cytometry and western blot analysis were used to determine the effects of FK506 and miR-429 on fibroblast apoptosis. The effects of FK506 and RhoE on fibroblast apoptosis were determined by CCK-8 assay, flow cytometry, and western blotting. We also evaluate the effects of FK506 and miR-429 on epidural fibrosis in rats by using histological analysis and TUNEL-staining. The results revealed FK506 induces fibroblast apoptosis and significantly downregulates miR-429 expression in fibroblasts. Additionally, miR-429 downregulation caused the apoptosis of fibroblasts. The luciferase activity assay confirmed that RhoE is a direct target of miR-429 and RhoE promotes fibroblast apoptosis. The rat model demonstrated miR-429 inhibition promotes fibroblast apoptosis and epidural fibrosis, which is consistent with the results of FK506 treatment. Our study demonstrates that FK506 induces fibroblast apoptosis and reduces epidural fibrosis by regulating miR-429 expression and its target of RhoE.

More than Just a Simple Cardiac Envelope; Cellular Contributions of the Epicardium

The adult pumping heart is formed by distinct tissue layers. From inside to outside, the heart is composed by an internal endothelial layer, dubbed the endocardium, a thick myocardial component which supports the pumping capacity of the heart and exteriorly covered by a thin mesothelial layer named the epicardium. Cardiac insults such as coronary artery obstruction lead to ischemia and thus to an irreversible damage of the myocardial layer, provoking in many cases heart failure and death. Thus, searching for new pathways to regenerate the myocardium is an urgent biomedical need. Interestingly, the capacity of heart regeneration is present in other species, ranging from fishes to neonatal mammals. In this context, several lines of evidences demonstrated a key regulatory role for the epicardial layer. In this manuscript, we provide a state-of-the-art review on the developmental process leading to the formation of the epicardium, the distinct pathways controlling epicardial precursor cell specification and determination and current evidences on the regenerative potential of the epicardium to heal the injured heart.

Intense light-elicited upregulation of miR-21 facilitates glycolysis and cardioprotection through Per2-dependent mechanisms

A wide search for ischemic preconditioning (IPC) mechanisms of cardioprotection identified the light elicited circadian rhythm protein Period 2 (Per2) to be cardioprotective. Studies on cardiac metabolism found a key role for light elicited Per2 in mediating metabolic dependence on carbohydrate metabolism. To profile Per2 mediated pathways following IPC of the mouse heart, we performed a genome array and identified 352 abundantly expressed and well-characterized Per2 dependent micro RNAs. One prominent result of our in silico analysis for cardiac Per2 dependent micro RNAs revealed a selective role for miR-21 in the regulation of hypoxia and metabolic pathways. Based on this Per2 dependency, we subsequently found a diurnal expression pattern for miR-21 with higher miR-21 expression levels at Zeitgeber time (ZT) 15 compared to ZT3. Gain or loss of function studies for miR-21 using miRNA mimics or miRNA inhibitors and a Seahorse Bioanalyzer uncovered a critical role of miR-21 for cellular glycolysis, glycolytic capacity, and glycolytic reserve. Exposing mice to intense light, a strategy to induce Per2, led to a robust induction of cardiac miR-21 tissue levels and decreased infarct sizes, which was abolished in miR-21-/- mice. Similarly, first translational studies in humans using intense blue light exposure for 5 days in healthy volunteers resulted in increased plasma miR-21 levels which was associated with increased phosphofructokinase activity, the rate-limiting enzyme in glycolysis. Together, we identified miR-21 as cardioprotective downstream target of Per2 and suggest intense light therapy as a potential strategy to enhance miR-21 activity and subsequent carbohydrate metabolism in humans.

MiR-21 is required for anti-tumor immune response in mice: an implication for its bi-directional roles

Here we show that miR-21, a microRNA known for its oncogenic activity, is also essential for mediating immune responses against tumor. Knockout of miR-21 in mice slowed the proliferation of both CD4⁺ and CD8⁺ cells, reduced their cytokine production and accelerated the grafted tumor growth. Further investigations indicated that miR-21 could activate CD4⁺ and CD8⁺ T cells via the PTEN/Akt pathway in response to stimulations. Taken together, these data suggest the key functions of miR-21 in mediating anti-tumor immune response and thereby uncover a bi-directional role of this traditionally known 'oncomiR' in tumorigenesis. Our study may provide new insights for the design of cancer therapies targeting microRNAs, with an emphasis on the dynamic and possibly unexpected role of these molecules.