MicroRNA-27a Regulates Cardiomyocytic Apoptosis During Cardioplegia-Induced Cardiac Arrest by Targeting Interleukin 10–Related Pathways

Low expression of miR-1929-3p mediates murine cytomegalovirus-induced fibrosis in cardiac fibroblasts via targeting endothelin a receptor/NLRP3 inflammasome pathway

MicroRNAs are crucial in the development of myocardial remodeling in hypertension. Low miR-1929-3p expression induced by murine cytomegalovirus (MCMV) infection is closely related to hypertensive myocardial remodeling. This study investigated the molecular mechanism of miR-1929-3p-induced myocardial remodeling after MCMV infection. We modeled MCMV-infected mouse cardiac fibroblasts (MMCFs) as the primary cell model. First, MCMV infection reduced the expression of miR-1929-3p and increased the mRNA and protein expression of its target gene endothelin receptor type A (ETAR) in mouse cardiac fibroblasts (MCFs), which demonstrated an internal relationship with myocardial fibrosis (MF) based on high proliferation, phenotypic transformation (α-SMA), and collagen expression in MMCFs. The transfection of the miR-1929-3p mimic downregulated the high expression of ETAR and alleviated these adverse effects in MMCFs. Inversely, these effects were exacerbated by the miR-1929-3p inhibitor. Second, the transfection of endothelin receptor type A over-expressed adenovirus (adETAR) reversed these positive effects of the miR-1929-3p mimic on MF improvement. Third, the transfection of adETAR exhibited a strong inflammatory response in MMCFs with increased expression of NOD-like receptors pyrin domain containing 3 (NLRP3) and increased secretion of interleukin-18. However, we found that the ETAR antagonist BQ123 and the selected NLRP3 inflammasome inhibitor MCC950 effectively eliminated the inflammatory response induced by both MCMV infection and miR-1929-3p inhibitor. Moreover, the MCF supernatant was related to cardiomyocyte hypertrophy. Our findings suggest that MCMV infection promotes MF by inducing the downregulation of miR-1929-3p and the high expression of ETAR, which activates NLRP3 inflammasomes in MCFs.

miR-302a-3p targets FMR1 to regulate pyroptosis of renal tubular epithelial cells induced by hypoxia-reoxygenation injury

NEW FINDINGS

What is the central question of this study? How does miR-302a-3p play a role in hypoxia-reoxygenation-induced pyroptosis of renal tubular epithelial cells? What is the main finding and its importance? Hypoxia-reoxygenation treatment upregulated the expression of miR-302a-3p in HK-2 cells, and then inhibited the transcription of FMRP translational regulator 1 (FMR1), so as to promote the activation of the NLRP3 inflammasome and aggravate the pyroptosis of HK-2 cells. miR-302a-3p was used as a molecular target in this study, which provides a new theoretical basis for the treatment of renal failure.

ABSTRACT

Hypoxia-reoxygenation (H/R) induction can affect miRNA expression and then control NLR family pyrin domain containing 3 (NLRP3) inflammasome-mediated pyroptosis. This study investigated the mechanism of miR-302a-3p in H/R-induced renal tubular epithelial cell (RTEC) pyroptosis. Human HK-2 RTECs were induced by H/R. Lactate dehydrogenase content, cell activity and pyroptosis, and levels of NLRP3, GSDMD-N, caspase-1, interleukin (IL)-1β, IL-18, superoxide dismutase, and malondialdehyde were detected to verify the effect of H/R on HK-2 cells. The NLRP3 inflammasome action was evaluated after H/R-induced HK-2 cells were treated with BAY11-7082, an inflammasome inhibitor. After inhibiting miR-302a-3p expression, the changes of pyroptosis were observed. The binding relation between miR-302a-3p and FMRP translational regulator 1 (FMR1) was verified. A function-rescue experiment verified the role of FMR1 in the regulation of pyroptosis. H/R-induced HK-2 cells showed significant pyroptosis injury, and the NLRP3 inflammasome was activated. After inhibiting the NLRP3 inflammasome, H/R-induced apoptosis was inhibited. After H/R treatment, miR-302a-3p in HK-2 cells was increased, and miR-302a-3p downregulation limited H/R-induced NLRP3 inflammasome-mediated pyroptosis. FMR1 is the target of miR-302a-3p. Inhibition of FMR1 alleviated the inhibition of H/R-induced HK-2 cell pyroptosis by miR-302a-3p inhibitor. Collectively, inhibiting miR-302a-3p can weaken its targeted inhibition on FMR1, thereby inhibiting the activation of NLRP3 inflammasomes and reducing caspase-1-dependent pyroptosis in HK-2 cells.

Prostaglandin E1 attenuates post‑cardiac arrest myocardial dysfunction through inhibition of mitochondria‑mediated cardiomyocyte apoptosis

Post‑cardiac arrest myocardial dysfunction (PAMD) is a leading cause of death in patients undergoing resuscitation patients following cardiac arrest (CA). Although prostaglandin E1 (PGE1) is a clinical drug used to mitigate ischemia injury, its effect on PAMD remains unknown. In the present study, the protective effects of PGE1 on PAMD were evaluated in a rat model of CA and in a hypoxia‑reoxygenation (H/R) in vitro model. Rats were randomly assigned to CA, CA+PGE1 or sham groups. Asphyxia for 8 min followed by cardiopulmonary resuscitation were performed in the CA and CA+PGE1 groups. PGE1 was intravenously administered at the onset of return of spontaneous circulation (ROSC). PGE1 treatment significantly increased the ejection fraction and cardiac output within 4 h following ROSC and improved the survival rate, compared with the CA group. Moreover, PGE1 inactivated GSK3β, prevented mitochondrial permeability transition pore (mPTP) opening, while reducing cytochrome c and cleaved caspase‑3 expression, as well as cardiomyocyte apoptosis in the rat model. To examine the underlying mechanism, H/R H9c2 cells were treated with PGE1 at the start of reoxygenation. The changes in GSK3β activity, mPTP opening, cytochrome c and cleaved caspase‑3 expression, and apoptosis of H9c2 cells were consistent with those noted in vivo. The results indicated that PGE1 attenuated PAMD by inhibiting mitochondria‑mediated cardiomyocyte apoptosis.

MiRNA-Mediated Mechanisms of Cardiac Protection in Ischemic and Remote Ischemic Preconditioning-A Qualitative Systematic Review

BACKGROUND

Ischemic preconditioning (IPC) and remote ischemic preconditioning (RIPC) protect myocardial tissue against subsequent ischemia and reperfusion injury (IRI) and have a high potential to improve patient outcome. The mediators and mechanisms of protection through IPC and RIPC remain largely unknown, but micro-RNAs (miRNAs) are promising candidates.

METHODS

Systematic review of Medline and Embase databases for biomedical scientific literature.

RESULTS

A total of 26 relevant publications (21 full-text original articles and 5 conference abstracts) were identified, 8 describing cell culture experiments, 14 animal experiments, and 4 randomized clinical trials in humans. Most commonly reported miRNAs with differential expression between preconditioned and control groups include miR-1, miR-21, and miR-144. Experimental designs and procedures differ widely, thereby limiting the potential to compare results between studies. Two of the four RCTs did not find any differentially expressed miRNAs.

CONCLUSIONS

Results from RCTs should feed back into basic research and focused studies confirming or rejecting hypotheses generated by these RCTs are needed.

Mechanism of Snhg8/miR-384/Hoxa13/FAM3A axis regulating neuronal apoptosis in ischemic mice model

Long noncoding RNAs, a subgroup of noncoding RNAs, are implicated in ischemic brain injury. The expression levels of Snhg8, miR-384, Hoxa13, and FAM3A were measured in chronic cerebral ischemia-induced HT22 cells and hippocampal tissues. The role of the Snhg8/miR-384/Hoxa13/FAM3A axis was evaluated in chronic cerebral ischemia models in vivo and in vitro. In this study, we found that Snhg8 and Hoxa13 were downregulated, while miR-384 was upregulated in chronic cerebral ischemia-induced HT22 cells and hippocampal tissues. Overexpression of Snhg8 and Hoxa13, and silencing of miR-384, all inhibited chronic cerebral ischemia-induced apoptosis of HT22 cells. Moreover, Snhg8 bound to miR-384 in a sequence-dependent manner and there was a reciprocal repression between Snhg8 and miR-384. Besides, overexpression of miR-384 impaired Hoxa13 expression by targeting its 3'UTR and regulated chronic cerebral ischemia-induced neuronal apoptosis. Hoxa13 bound to the promoter of FAM3A and enhanced its promotor activity, which regulated chronic cerebral ischemia-induced neuronal apoptosis. Remarkably, the in vivo experiments demonstrated that Snhg8 overexpression combined with miR-384 knockdown led to an anti-apoptosis effect. These results reveal that the Snhg8/miR-384/Hoxa13/FAM3A axis plays a critical role in the regulation of chronic cerebral ischemia-induced neuronal apoptosis.

miR-27a-5p Attenuates Hypoxia-induced Rat Cardiomyocyte Injury by Inhibiting Atg7

Acute myocardial infarction (AMI) is an ischemic heart disease with high mortality worldwide. AMI triggers a hypoxic microenvironment and induces extensive myocardial injury, including autophagy and apoptosis. MiRNAs, which are a class of posttranscriptional regulators, have been shown to be involved in the development of ischemic heart diseases. We have previously reported that hypoxia significantly alters the miRNA transcriptome in rat cardiomyoblast cells (H9c2), including miR-27a-5p. In the present study, we further investigated the potential function of miR-27a-5p in the cardiomyocyte response to hypoxia, and showed that miR-27a-5p expression was downregulated in the H9c2 cells at different hypoxia-exposed timepoints and the myocardium of a rat AMI model. Follow-up experiments revealed that miR-27a-5p attenuated hypoxia-induced cardiomyocyte injury by regulating autophagy and apoptosis via Atg7, which partly elucidated the anti-hypoxic injury effects of miR-27a-5p. Taken together, this study shows that miR-27a-5p has a cardioprotective effect on hypoxia-induced H9c2 cell injury, suggesting it may be a novel target for the treatment of hypoxia-related heart diseases.

Circulating miR-26a-1, miR-146a and miR-199a-1 are potential candidate biomarkers for acute myocardial infarction

BACKGROUND

Acute myocardial infarction (AMI) was considered to be one of the major causes of morbidity and mortality worldwide. In order to manage the acute myocardial infarction outbreaks, accurate biomarkers for risk prediction are needed. Circulating microRNAs (miRNAs) may act as diagnostic and prognostic biomarkers for cardiovascular events.

METHODS

This study aimed to determine the possibility of circulating miRNAs used as biomarkers for AMI and their dynamic expression levels before and after percutaneous coronary intervention (PCI) in patients. Circulating miR-26a-1, miR-27a, miR-30d, miR-146a, miR-199a-1 and miR-423 were selected and validated in 31 AMI patients and 27 matched controls by quantitative real-time PCR (qPCR).

RESULTS

The expression levels of plasma miR-26a-1, miR-146a and miR-199a-1 were significantly increased in AMI patients. Receiver operating characteristic (ROC) analysis indicated that miR-26a-1, miR-146a and miR-199a-1 showed considerable diagnostic efficiency for predicting AMI. Furthermore, we demonstrated that the combination of miR-26a-1, miR-146a and miR-199a-1 facilitated AMI diagnosis.

CONCLUSIONS

Our findings suggest that circulating miR-26a-1, miR-146a and miR-199a-1 have the potential to be used as biomarkers for AMI diagnosis.

RETRACTED: Protective effect of down-regulated microRNA-27a mediating high thoracic epidural block on myocardial ischemia-reperfusion injury in mice through regulating ABCA1 and NF-κB signaling pathway

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. An Expression of Concern for this article was previously published while an investigation was conducted (see related editorial: https://doi.org/10.1016/j.biopha.2022.113812). This retraction notice supersedes the Expression of Concern published earlier. Concern was raised about the reliability of the heart images shown in Figure 1A, which appear to contain similar features to those found in other publications, as detailed here: https://pubpeer.com/publications/108A0BE9F52724D6879E23FAE7F361; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. Concerns over the provenance of the flow cytometry data in Figure 7A were also raised. The journal requested the corresponding author comment on these concerns and provide the associated raw data. The authors did not respond to this request and therefore the Editor-in-Chief decided to retract the article.

Ambiguous Effects of Autophagy Activation Following Hypoperfusion/Ischemia

Autophagy primarily works to counteract nutrient deprivation that is strongly engaged during starvation and hypoxia, which happens in hypoperfusion. Nonetheless, autophagy is slightly active even in baseline conditions, when it is useful to remove aged proteins and organelles. This is critical when the mitochondria and/or proteins are damaged by toxic stimuli. In the present review, we discuss to that extent the recruitment of autophagy is beneficial in counteracting brain hypoperfusion or, vice-versa, its overactivity may per se be detrimental for cell survival. While analyzing these opposite effects, it turns out that the autophagy activity is likely not to be simply good or bad for cell survival, but its role varies depending on the timing and amount of autophagy activation. This calls for the need for an appropriate autophagy tuning to guarantee a beneficial effect on cell survival. Therefore, the present article draws a theoretical pattern of autophagy activation, which is hypothesized to define the appropriate timing and intensity, which should mirrors the duration and severity of brain hypoperfusion. The need for a fine tuning of the autophagy activation may explain why confounding outcomes occur when autophagy is studied using a rather simplistic approach.

MicroRNA 27a-3p Regulates Antimicrobial Responses of Murine Macrophages Infected by Mycobacterium avium subspecies paratuberculosis by Targeting Interleukin-10 and TGF-β-Activated Protein Kinase 1 Binding Protein 2

Mycobacterium avium subspecies paratuberculosis (MAP) persistently survive and replicate in mononuclear phagocytic cells by adopting various strategies to subvert host immune response. Interleukin-10 (IL-10) upregulation via inhibition of macrophage bactericidal activity is a critical step for MAP survival and pathogenesis within the host cell. Mitogen-activated protein kinase p38 signaling cascade plays a crucial role in the elevation of IL-10 and progression of MAP pathogenesis. The contribution of microRNAs (miRNAs) and their influence on the activation of macrophages during MAP pathogenesis are still unclear. In the current study, we found that miRNA-27a-3p (miR-27a) expression is downregulated during MAP infection both in vivo and in vitro. Moreover, miR-27a is also downregulated in toll-like receptor 2 (TLR2)-stimulated murine macrophages (RAW264.7 and bone marrow-derived macrophage). ELISA and real-time qRT-PCR results confirm that overexpression of miR-27a inhibited MAP-induced IL-10 production in macrophages and upregulated pro-inflammatory cytokines, while miR-27a inhibitor counteracted these effects. Luciferase reporter assay results revealed that IL-10 and TGF-β-activated protein kinase 1 binding protein 2 (TAB 2) are potential targets of miR-27a. In addition, we demonstrated that miR-27a negatively regulates TAB 2 expression and diminishes TAB 2-dependent p38/JNK phosphorylation, ultimately downregulating IL-10 expression in MAP-infected macrophages. Furthermore, overexpression of miR-27a significantly inhibited the intracellular survival of MAP in infected macrophages. Our data show that miR-27a augments antimicrobial activities of macrophages and inhibits the expression of IL-10, demonstrating that miR-27a regulates protective innate immune responses during MAP infection and can be exploited as a novel therapeutic target in the control of intracellular pathogens, including paratuberculosis.

The association between pre-miR-27a rs895819 polymorphism and myocardial infarction risk in a Chinese Han population

Background

Accumulating evidences have shown that miRNAs are directly or indirectly involved in a variety of biological processes, and closely associated with diverse human diseases, including cardiovascular diseases. SNPs locating within pri/pre-miRNA can affect miRNA processing and binding ability of target genes. MiR-27a, miR-26a-1 miR-100, miR-126 and miR-218 were reported to be associated with pathogenesis of myocardial infarction (MI). Here we aimed to evaluate the potential association of five polymorphisms in these pri/pre-miRNAs with individual susceptibility to MI in a Chinese Han population.

Methods

Genotyping was performed in 287 MI cases and 646 control subjects using polymerase chain reaction-ligase detection reaction (PCR-LDR) method. The association of these SNPs with MI risk was performed with SPSS software.

Results

In a logistic regression analysis, we found that AG heterozygote (OR = 0.40, 95% CI = 0.21-0.76, Pa = 0.005) or AA homozygote (OR = 0.40, 95% CI = 0.22-0.75, Pa = 0.004) of pre-miR-27a rs895819 had a reduced susceptibility to MI in comparison with GG homozygote. Similarly, a reduced risk of MI was detected when the AG and AA genotypes were combined (OR = 0.40, 95% CI = 0.22-0.74, Pa = 0.003). However, no significant association between pri-miR-26a-1 pri-miR-100, pri-miR-126 and pri-miR-218 polymorphisms and MI risk was observed under the allelic and established genetic models. Further stratified analysis of pre-miR-27a rs895819 revealed a more significant association of AG + AA genotypes with MI risk among younger, male and smoking subjects. Interestingly, AG and AA genotypes of the rs895819 polymorphism conferred about 0.17 mmol/L and 0.18 mmol/L increase in HDL-C levels compared to GG genotype.

Conclusions

Our findings suggest that the pre-miR-27a rs895819 polymorphism is associated with MI susceptibility in the Chinese Han population, which probably due to influence the HDL-C levels.

Electronic supplementary material

The online version of this article (10.1186/s12944-017-0652-x) contains supplementary material, which is available to authorized users.

MicroRNA as a Therapeutic Target in Cardiac Remodeling

MicroRNAs (miRNAs) are small RNA molecules that contain 18–25 nucleotides. The alterations in their expression level play crucial role in the development of many disorders including heart diseases. Myocardial remodeling is the final pathological consequence of a variety of myocardial diseases. miRNAs have central role in regulating pathogenesis of myocardial remodeling by modulating cardiac hypertrophy, cardiomyocytes injury, cardiac fibrosis, angiogenesis, and inflammatory response through multiple mechanisms. The balancing and tight regulation of different miRNAs is a key to drive the cellular events towards functional recovery and any fall in this leads to detrimental effect on cardiac function following various insults. In this review, we discuss the impact of alterations of miRNAs expression on cardiac hypertrophy, cardiomyocytes injury, cardiac fibrosis, angiogenesis, and inflammatory response. We have also described the targets (receptors, signaling molecules, transcription factors, etc.) of miRNAs on which they act to promote or attenuate cardiac remodeling processes in different type cells of cardiac tissues.

Cardiac mitochondrial dynamics: miR-mediated regulation during cardiac injury

Mitochondrial integrity is indispensable for cardiac health. With the advent of modern imaging technologies, mitochondrial motility and dynamics within the cell are extensively studied. Terminally differentiated and well-structured cardiomyocytes depict little mitochondrial division and fusion, questioning the contribution of mitochondrial fusion proteins (Mitofusin 1/2 and Optic Atrophy 1 protein) and fission factors (Dynamin-like protein 1 and mitochondrial fission 1 protein) in cardiomyocyte homeostasis. Emerging evidences suggest that alterations in mitochondrial morphology from globular, elongated network to punctate fragmented disconnected structures are a pathological response to ensuing cardiac stress and cardiomyocyte cell death, bringing forth the following question, "what maintains this balance between fusion and fission?" The answer hinges upon the classical "junk" DNA: microRNAs, the endogenous non-coding RNAs. Because of their essential role in numerous signaling pathways, microRNAs are considered to play major roles in the pathogenesis of various diseases. Mitochondria are not exempted from microRNA-mediated regulation. This review defines the importance of mitochondrial structural integrity and the microRNA-mitochondrial dynamics tandem, an imminent dimension of the cardiac homeostasis network. Elucidating their coordinated interaction could spur RNA-based therapeutics for resuscitating functional mitochondrial population during cardiovascular disorders.

Inhibition of miR-302 Suppresses Hypoxia-Reoxygenation-Induced H9c2 Cardiomyocyte Death by Regulating Mcl-1 Expression

MicroRNAs play important roles in cell proliferation, differentiation, and apoptosis, and their expression influences cardiomyocyte apoptosis resulting from ischemia-induced myocardial infarction. Here, we determined the role of miR expression in cardiomyocyte apoptosis during hypoxia and reoxygenation. The rat cardiomyocyte cell line H9c2 was incubated for 3 h in normal or hypoxia medium, followed by reoxygenation for 24 h and transfection with a miR-302 mimic or antagomir. The effect of miR-302 on myeloid leukemia cell-differentiation protein-1 (Mcl-1) expression was determined by western blot, real-time polymerase chain reaction, and luciferase reporter assays, with cell viability assays. We observed that miR-302 expression was elevated by hypoxia/reoxygenation injury and increased further or decreased by transfection of the miR-302 mimic or miR-302 antagomir, respectively. Additionally, elevated miR-302 levels increased apoptosis-related protein levels and cardiomyocyte apoptosis, and luciferase reporter assays revealed miR-302 binding to the Mcl-1 mRNA 3' untranslated region. Our findings suggested that miR-302 overexpression aggravated hypoxia/reoxygenation-mediated cardiomyocyte apoptosis by inhibiting antiapoptotic Mcl-1 expression, thereby activating proapoptotic molecules. Furthermore, results indicating cardiomyocyte rescue from hypoxia/reoxygenation injury following treatment with miR-302 antagomir suggested that miR-302 inhibition might constitute a therapeutic strategy for protection against cardiomyocyte apoptosis during hypoxia/reoxygenation injury.

Effect of miRNA-27a and Leptin Polymorphisms on Risk of Recurrent Spontaneous Abortion

Background

The aim of this study was to investigate the possible associations of miRNA-27a and Leptin polymorphisms with the risk of recurrent spontaneous abortion (RSA).

Material/Methods

Between May 2013 and April 2015 at Shenzhen Longhua New District Central Hospital, we randomly recruited 138 RSA patients as the case group and another 142 normal pregnancy women as the control group. We used denaturing high-performance liquid chromatography (DHPLC) to determine the genotypes and allele frequencies of miRNA-27a rs895819 A/G and Leptin rs7799039 G/A.

Results

The GG genotype and G allele frequencies of miRNA-27a rs895819 A/G were higher in the case group than in the control group, and the AA genotype and A allele frequencies of Leptin rs7799039 G/A were also higher in the case group than in the control group (all P<0.05). MiRNA-27a rs895819 A/G and Leptin rs7799039 G/A polymorphisms increased the risk of RSA (Exp (B)=2.732, 95% CI=1.625~4.596, P=0.000; Exp (B)=4.081, 95% CI=1.817~9.164, P=0.001). GG-AA or AG-AA carriers had a higher risk of RSA. The miRNA-27a expression of AA carriers of miRNA-27a rs895819 was lower than that of AG+GG carriers both in the case and control groups (all P=0.024). The plasma leptin concentration of GG carriers was lower than that of GA+AA carriers in the case group (P=0.026).

Conclusions

The polymorphisms of miRNA-27a rs895819 A/G and Leptin rs7799039 G/A may contribute to an increased risk of RSA.

The role of microRNAs in the control and mechanism of action of IL-10

Recent studies have shown an important interplay between Interleukin 10 (IL-10) and microRNAs. IL-10 can be directly post-transcriptionally regulated by several microRNA, including miR-106a, miR-4661, miR-98, miR-27, let7 and miR-1423p/5p. miRNA targeting of IL-10 has been suggested to play a role in autoimmune and inflammatory diseases such as SLE, reperfusion injury and asthma. Another miRNA, miR-21, has been shown to indirectly regulate IL-10 via downregulation of the IL-10 inhibitor PDCD4. The targeting of IL-10 in this way has been linked to host defence modulation by Mycobacterium leprae. Viral miRNAs, such as miR-K12-3 from Kaposi's sarcoma-associated herpesvirus (KSHV), can also decrease IL-10 to promote tumour development. Finally this interplay can operate in a feedback loop, with IL-10 capable of regulating microRNAs, upregulating those that can contribute to exerting the anti-inflammatory response, such as miR-187, and downregulating those that are highly pro-inflammatory, such as miR-155. Understanding the two-way regulation between miRNA and IL-10 is giving rise to new insights into this important cytokine.

Regulatory RNAs and paracrine networks in the heart

Cardiac hypertrophy and fibrosis are two closely related adaptive response mechanisms of the myocardium to mechanical, metabolic, and genetic stress that finally contribute to the development of heart failure (HF). This relation is based on a dynamic interplay between many cell types including cardiomyocytes and fibroblasts during disease progression. Both cell types secrete a variety of growth factors, cytokines, and hormones that influence hypertrophic cardiomyocyte growth and fibrotic fibroblast activation in a paracrine and autocrine manner. It has become evident that, aside proteinous signals, microRNAs (miRNAs) and possible other RNA species such as long non-coding RNAs are potential players in such a cell-to-cell communication. By directly acting as paracrine signals or by modulating downstream intercellular signalling mediators, miRNAs can act as moderators of the intercellular crosstalk. These small regulators can potentially be secreted in a 'mircrine' fashion, so that miRNAs can be assumed as the message itself. This review will summarize the recent findings about the paracrine crosstalk between cardiac fibroblasts and cardiomyocytes and addresses how miRNAs may be involved in this interplay. It also highlights therapeutic strategies targeting factors of pathological communication for the treatment of HF.