Knockdown of LncRNA Lcn2-204 alleviates sepsis-induced myocardial injury by regulation of iron overload and ferroptosis.

Ferroptosis is an iron-dependent programmed cell death form resulting from lipid peroxidation damage, it plays a key role in organ damage and tumor development from various causes. Sepsis leads to severe host response after infection with high mortality. The long non-coding RNAs (LncRNAs) are involved in different pathophysiological mechanisms of multiple diseases. Here, we used cecal ligation and puncture (CLP) operation to mimic sepsis induced myocardial injury (SIMI) in mouse model, and LncRNAs and mRNAs were profiled by Arraystar mouse LncRNA Array V3.0. Based on the microarray results, 552 LncRNAs and 520 mRNAs were differentially expressed in the sham and CLP groups, among them, LncRNA Lcn2-204 was the highest differentially expressed up-regulated LncRNA. Iron metabolism disorder was involved in SIMI by bioinformatics analysis, meanwhile, myocardial iron content and lipocalin-2 (Lcn2) protein expressions were increased. The CNC network comprised 137 positive interactions and 138 negative interactions. Bioinformatics analysis showed several iron-related terms were enriched and six genes (Scara5, Tfrc, Lcn2, Cp, Clic5, Ank1) were closely associated with iron metabolism. Then, we constructed knockdown LncRNA Lcn2-204 targeting myocardium and found that it ameliorated cardiac injury in mouse sepsis model through modulating iron overload and ferroptosis. In addition, we found that LncRNA Lcn2-204 was involved in the regulation of Lcn2 expression in septic myocardial injury. Based on these findings, we conclude that iron overload and ferroptosis are the key mechanisms leading to myocardial injury in sepsis, knockdown of LncRNA Lcn2-204 plays the cardioprotective effect through inhibition of iron overload, ferroptosis and Lcn2 expression. It may provide a novel therapeutic approach to ameliorate sepsis-induced myocardial injury.

Malat1 deficiency prevents neonatal heart regeneration by inducing cardiomyocyte binucleation.

The adult mammalian heart has limited regenerative capacity, while the neonatal heart fully regenerates during the first week of life. Postnatal regeneration is mainly driven by proliferation of preexisting cardiomyocytes and supported by proregenerative macrophages and angiogenesis. Although the process of regeneration has been well studied in the neonatal mouse, the molecular mechanisms that define the switch between regenerative and nonregenerative cardiomyocytes are not well understood. Here, using in vivo and in vitro approaches, we identified the lncRNA Malat1 as a key player in postnatal cardiac regeneration. Malat1 deletion prevented heart regeneration in mice after myocardial infarction on postnatal day 3 associated with a decline in cardiomyocyte proliferation and reparative angiogenesis. Interestingly, Malat1 deficiency increased cardiomyocyte binucleation even in the absence of cardiac injury. Cardiomyocyte-specific deletion of Malat1 was sufficient to block regeneration, supporting a critical role of Malat1 in regulating cardiomyocyte proliferation and binucleation, a landmark of mature nonregenerative cardiomyocytes. In vitro, Malat1 deficiency induced binucleation and the expression of a maturation gene program. Finally, the loss of hnRNP U, an interaction partner of Malat1, induced similar features in vitro, suggesting that Malat1 regulates cardiomyocyte proliferation and binucleation by hnRNP U to control the regenerative window in the heart.

Inflammatory Glycoprotein YKL-40 Is Elevated after Coronary Artery Bypass Surgery and Correlates with Leukocyte Chemotaxis and Myocardial Injury, a Pilot Study.

The aim of the present study was to investigate the levels of YKL-40 during and after coronary artery bypass grafting surgery (CABG) and to establish possible connections between YKL-40 and markers of oxidative stress, inflammation, and myocardial injury. Patients undergoing elective CABG utilizing cardiopulmonary bypass (CPB) were recruited into the study. Blood samples were collected at the onset of anesthesia, during surgery and post-operatively. Levels of YKL-40, 8-isoprostane, interleukin-8 (IL-8), monocyte chemotactic protein-1 (MCP-1) and troponin T (TnT) were measured by immunoassay. YKL-40 levels increased significantly 24 h after CPB. Positive correlation was seen between post-operative TnT and YKL-40 levels (r = 0.457, p = 0.016) and, interestingly, baseline YKL-40 predicted post-operative TnT increase (r = 0.374, p = 0.050). There was also a clear association between YKL-40 and the chemotactic factors MCP-1 (r = 0.440, p = 0.028) and IL-8 (r = 0.484, p = 0.011) linking YKL-40 to cardiac inflammation and fibrosis following CABG. The present results show, for the first time, that YKL-40 is associated with myocardial injury and leukocyte-activating factors following coronary artery bypass surgery. YKL-40 may be a factor and/or biomarker of myocardial inflammation and injury and subsequent fibrosis following heart surgery.

UTP14A, DKC1, DDX10, PinX1, and ESF1 Modulate Cardiac Angiogenesis Leading to Obesity-Induced Cardiac Injury.

Background: This study is aimed at exploring the key genes and the possible mechanism of heart damage caused by obesity. Methods: We analyzed the GSE98226 dataset. Firstly, differentially expressed genes (DEGs) were identified in heart tissues of obese and normal mice. Then, we analyzed DEGs using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Thirdly, we constructed a protein-protein interaction (PPI) network and key modules and searched hub genes. Finally, we observed the pathological changes associated with obesity through histopathology. Results: A total of 763 DEGs were discovered, including 629 upregulated and 134 downregulated genes. GO enrichment analysis showed that these DEGs were mainly related to the regulation of transcription, DNA-templated, nucleic acid binding, and metal ion binding. KEGG pathway analysis revealed that the DEGs were enriched in long-term depression, gap junction, and sphingolipid signaling pathways. Finally, we identified UTP14A, DKC1, DDX10, PinX1, and ESF1 as the hub genes. Histopathologic analysis showed that obesity increased the number of collagen fibers and decreased the number of microvessels and proliferation of the endothelium and increased endothelial cell damage which further leads to dysfunction of cardiac microcirculation. Conclusion: UTP14A, DKC1, DDX10, PinX1, and ESF1 have been identified as hub genes in obesity-induced pathological changes in the heart and may be involved in obesity-induced cardiac injury by affecting cardiac microcirculatory function.

Exosomes derived from the blood of patients with sepsis regulate apoptosis and aerobic glycolysis in human myocardial cells via the hsa­miR­1262/SLC2A1 signaling pathway.

Myocardial injury occurs in the majority of patients with sepsis and is associated with early mortality. MicroRNAs (miRs) transported by exosomes have been implicated in numerous diseases, such as tumors, acute myocardial infarction and cardiovascular disease. Human serum albumin (hsa)­miR­1262 has been shown to serve a role in sepsis; however, its role in exosomes isolated from patients with sepsis and septic myocardial injury remains unclear. In the present study, serum exosomes were isolated via ultracentrifugation. Solute carrier family 2 member 1 (SLC2A1), an essential mediator in energy metabolism, was silenced and overexpressed in the human myocardial AC16 cell line using lentiviral plasmids containing either SLC2A1­targeting short interfering RNAs or SLC2A1 cDNA, respectively. Cell apoptosis was analyzed using flow cytometry, and the extracellular acidification rate and oxygen consumption rate of AC16 cells were determined using an XFe24 Extracellular Flux Analyzer. Furthermore, the dual­luciferase reporter assay was used to evaluate the interaction between hsa­miR­1262 and SLC2A1. Finally, reverse transcription­quantitative PCR and western blotting were used to evaluate gene and protein expression levels, respectively. Exosomes isolated from the blood of patients with sepsis (Sepsis­exo) markedly reduced aerobic glycolysis activity, but significantly promoted the apoptosis of human AC16 cells in a time­dependent manner. Moreover, Sepsis­exo significantly increased hsa­miR­1262 expression levels, but significantly decreased SLC2A1 mRNA expression levels in a time­dependent manner. Bioinformatics analysis indicated that hsa­miR­1262 bound to the 3' untranslated region of SLC2A1 to negatively regulate its expression. The silencing of SLC2A1 promoted apoptosis and suppressed glycolysis in AC16 cells, whereas SLC2A1 overexpression resulted in the opposite effects. Therefore, the present study demonstrated that exosomes derived from patients with sepsis may inhibit glycolysis and promote the apoptosis of human myocardial cells through exosomal hsa­miR­1262 via its target SLC2A1. These findings highlighted the importance of the hsa­miR­1262/SLC2A1 signaling pathway in septic myocardial injury and provided novel insights into therapeutic strategies for septic myocardial depression.

Cardiomyocytes disrupt pyrimidine biosynthesis in nonmyocytes to regulate heart repair.

Various populations of cells are recruited to the heart after cardiac injury, but little is known about whether cardiomyocytes directly regulate heart repair. Using a murine model of ischemic cardiac injury, we demonstrate that cardiomyocytes play a pivotal role in heart repair by regulating nucleotide metabolism and fates of nonmyocytes. Cardiac injury induced the expression of the ectonucleotidase ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), which hydrolyzes extracellular ATP to form AMP. In response to AMP, cardiomyocytes released adenine and specific ribonucleosides that disrupted pyrimidine biosynthesis at the orotidine monophosphate (OMP) synthesis step and induced genotoxic stress and p53-mediated cell death of cycling nonmyocytes. As nonmyocytes are critical for heart repair, we showed that rescue of pyrimidine biosynthesis by administration of uridine or by genetic targeting of the ENPP1/AMP pathway enhanced repair after cardiac injury. We identified ENPP1 inhibitors using small molecule screening and showed that systemic administration of an ENPP1 inhibitor after heart injury rescued pyrimidine biosynthesis in nonmyocyte cells and augmented cardiac repair and postinfarct heart function. These observations demonstrate that the cardiac muscle cell regulates pyrimidine metabolism in nonmuscle cells by releasing adenine and specific nucleosides after heart injury and provide insight into how intercellular regulation of pyrimidine biosynthesis can be targeted and monitored for augmenting tissue repair.

Effects of platelet rich plasma on experimentally induced diabetic heart injury.

Diabetic heart is one of the common complications of diabetes mellitus. Platelet-rich plasma (PRP) is an autologous product rich in growth factors that can enhance tissue regeneration. This work was conducted to study the PRP ability to improve diabetes-inducing cardiac changes. Also, it sheds more light on the possible mechanisms through which PRP induces its effects. Rats were divided into; control, PRP, diabetic, and PRP-diabetic groups. Cardiac specimens were obtained and processed for biochemical, histological, and immunohistochemical study. The diabetic group exhibited a significant increase in cardiac oxidative stress, inflammation, and cardiac injury markers if compared with the control group. Additionally, the cardiac tissue showed variable morphological changes in the form of focal distortion and loss of cardiac myocytes. Distorted mitochondria and heterochromatic nuclei were observed in the cardiac muscle fibers. The mean number of charcoal-stained macrophages, and mean area fraction for collagen fibers, mean number of PCNA-immune positive cardiac muscle were significantly decrease in PRP- diabetic group. Collectively, the results showed that PRP treatment ameliorated most of all these previous changes. CONCLUSION: PRP ameliorated the diabetic cardiac injury via inhibition of oxidative stress and inflammation. It was confirmed by biochemical, histological, and immunohistochemical study. It could be concluded that PRP could be used as a potential therapy for diabetic heart.

Long Non-Coding RNA Small Nucleolar RNA Host Gene 1 Alleviates Sepsis-Associated Myocardial Injury by Modulating the miR-181a-5p/XIAP Axis in vitro.

OBJECTIVE: Sepsis is a systemic inflammatory response syndrome that results in severe myocardial injury. This study aimed to explore the role and mechanism of long non-coding RNA (lncRNA) small nucleolar RNA host gene 1 (SNHG1) in sepsis-induced myocardial injury in vitro. METHODS: Embryonic rat ventricular myocardial cell line (H9c2) was treated with lipopolysaccharide (LPS) to simulate sepsis-induced myocardial injury in vitro. A quantitative real-time polymerase chain reaction was executed to determine the expression of SNHG1 and microRNA (miR)-181a-5p. 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-h-tetrazolium bromide assay was employed to measure cell viability. The levels of inflammatory factors (tumor necrosis factor alpha [TNF-α], interleukin 6 [IL-6], and IL-1ß) were measured by enzyme-linked immunosorbent assay. Oxidative stress was assessed by measuring malondialdehyde, superoxide dismutase, and lactate dehydrogenase. The targeted interrelations among SNHG1, miR-181a-5p, and X-linked inhibitor of apoptosis protein (XIAP) were verified by dual-luciferase reporter assay. Relative protein expression of XIAP was detected by western blot. RESULTS: SNHG1 and XIAP were down-regulated, and miR-181a-5p was up-regulated in LPS-induced H9c2 cells. Overexpression of SNHG1 or inhibition of miR-181a-5p facilitated cell viability and repressed inflammation and oxidative stress in LPS-treated H9c2 cells. MiR-181a-5p was a target of and negatively regulated by SNHG1. At the same time, XIAP was a target gene of and inversely modulated by miR-181a-5p. In addition, XIAP was positively regulated by SNHG1. Up-regulation of miR-181a-5p or silencing of XIAP reversed the inhibitory effects of SNHG1 on inflammation and oxidative stress, as well as the promoting effects on cell viability in LPS-induced H9c2 cells. CONCLUSION: SNHG1 protected H9c2 cells against LPS-induced injury through modulating the miR-181a-5p/XIAP axis.

Melatonin alleviates sepsis-induced heart injury through activating the Nrf2 pathway and inhibiting the NLRP3 inflammasome.

Melatonin improved the outcome of septic cardiomyopathy by inhibiting NLRP3 priming induced by reactive oxygen species. To get insights into these events, we studied the melatonin/Nrf2 antioxidant pathways during sepsis in the heart of NLRP3-deficient mice. Sepsis was induced by cecal ligation and puncture and melatonin was given at a dose of 30 mg/kg. Nuclear turnover of Nrf2 and p-Ser40 Nrf2 and expression of ho-1 were enhanced in nlrp3+/+ and nlrp3-/- mice during sepsis. Sepsis caused higher mitochondria impairment, apoptotic and autophagic events in nlrp3+/+ mice than in nlrp3-/- animals. These findings were accompanied by greater levels of Parkin and PINK-1, and lower Mfn2/Drp-1 ratio in nlrp3+/+ than in nlrp3-/- mice during sepsis, supporting less mitophagy in the latter. Ultrastructural analysis of myocardial tissue further confirmed these observations. The activation of NLRP3 inflammasome accounted for most of the deleterious effects of sepsis, whereas the Nrf2-dependent antioxidative response activation in response to sepsis was unable to neutralize these events. In turn, melatonin further enhanced the Nrf2 response in both mice strains and reduced the NLRP3 inflammasome activation in nlrp3+/+ mice, restoring myocardial homeostasis. The data support that the anti-inflammatory efficacy of melatonin against sepsis depends, at least in part, on Nrf2 activation.

iASPP protects the heart from ischemia injury by inhibiting p53 expression and cardiomyocyte apoptosis.

Currently, there remains a great need to elucidate the molecular mechanism of acute myocardial infarction in order to facilitate the development of novel therapy. Inhibitor of apoptosis-stimulating protein of p53 (iASPP) is a member of the ASPP family proteins and an evolutionarily preserved inhibitor of p53 that is involved in many cellular processes, including apoptosis of cancer cells. The purpose of this study was to investigate the possible role of iASPP in acute myocardial infarction. The protein level of iASPP was markedly reduced in the ischemic hearts in vivo and hydrogen peroxide-exposed cardiomyocytes in vitro. Overexpression of iASPP reduced the infarct size and cardiomyocyte apoptosis of mice subjected to 24 h of coronary artery ligation. Echocardiography showed that cardiac function was improved as indicated by the increase in ejection fraction and fractional shortening. In contrast, knockdown of iASPP exacerbated cardiac injury as manifested by impaired cardiac function, increased infarct size, and apoptosis rate. Mechanistically, overexpression of iASPP inhibited, while knockdown of iASPP increased the expressions of p53 and Bax, the key regulators of apoptosis. Taken together, our results suggested that iASPP is an important regulator of cardiomyocyte apoptosis, which represents a potential target in the therapy of myocardial infarction.

Exosomal LncRNA-NEAT1 derived from MIF-treated mesenchymal stem cells protected against doxorubicin-induced cardiac senescence through sponging miR-221-3p.

BACKGROUND: The chemotherapy drug doxorubicin (Dox) is widely used for treating a variety of cancers. However, its high cardiotoxicity hampered its clinical use. Exosomes derived from stem cells showed a therapeutic effect against Dox-induced cardiomyopathy (DIC). Previous studies reported that exosomes derived from mesenchymal stem cells (MSCs) pretreated with macrophage migration inhibitory factor (MIF) (exosomeMIF) showed a cardioprotective effect through modulating long noncoding RNAs/microRNAs (lncRNAs/miRs). This study aimed to investigate the role of exosomeMIF in the treatment of DIC. RESULTS: Exosomes were isolated from control MSCs (exosome) and MIF-pretreated MSCs (exosomeMIF). Regulatory lncRNAs activated by MIF pretreatment were explored using genomics approaches. Fluorescence-labeled exosomes were tracked in vitro by fluorescence imaging. In vivo and in vitro, miR-221-3p mimic transfection enforced miR-221-3p overexpression, and senescence-associated ß-galactosidase assay was applied to test cellular senescence. Exosomal delivering LncRNA-NEAT1 induced therapeutic effect in vivo was confirmed by echocardiography. It demonstrated that exosomesMIF recovered the cardiac function and exerted the anti-senescent effect through LncRNA-NEAT1 transfer against Dox. TargetScan and luciferase assay showed that miR-221-3p targeted the Sirt2 3'-untranslated region. Silencing LncRNA-NEAT1 in MSCs, miR-221-3p overexpression or Sirt2 silencing in cardiomyocytes decreased the exosomeMIF-induced anti-senescent effect against Dox. CONCLUSIONS: The results indicated exosomeMIF serving as a promising anti-senescent effector against Dox-induced cardiotoxicity through LncRNA-NEAT1 transfer, thus inhibiting miR-221-3p and leading to Sirt2 activation. The study proposed that exosomeMIF might have the potential to serve as a cardioprotective therapeutic agent during cancer chemotherapy.

MicroRNA signatures of perioperative myocardial injury after elective noncardiac surgery: a prospective observational mechanistic cohort study.

BACKGROUND: Elevated plasma or serum troponin, indicating perioperative myocardial injury (PMI), is common after noncardiac surgery. However, underlying mechanisms remain unclear. Acute coronary syndrome (ACS) is associated with the early appearance of circulating microRNAs, which regulate post-translational gene expression. We hypothesised that if PMI and ACS share pathophysiological mechanisms, common microRNA signatures should be evident. METHODS: We performed a nested case control study of samples obtained before and after noncardiac surgery from patients enrolled in two prospective observational studies of PMI (postoperative troponin I/T>99th centile). In cohort one, serum microRNAs were compared between patients with or without PMI, matched for age, gender, and comorbidity. Real-time polymerase chain reaction quantified (qRT-PCR) relative microRNA expression (cycle quantification [Cq] threshold <37) before and after surgery for microRNA signatures associated with ACS, blinded to PMI. In cohort two, we analysed (EdgeR) microRNA from plasma extracellular vesicles using next-generation sequencing (Illumina HiSeq 500). microRNA-messenger RNA-function pathway analysis was performed (DIANA miRPath v3.0/TopGO). RESULTS: MicroRNAs were detectable in all 59 patients (median age 67 yr [61-75]; 42% male), who had similar clinical characteristics independent of developing PMI. In cohort one, serum microRNA expression increased after surgery (mean fold-change) hsa-miR-1-3p: 3.99 (95% confidence interval [CI: 1.95-8.19]; hsa-miR-133-3p: 5.67 [95% CI: 2.94-10.91]; P<0.001). These changes were not associated with PMI. Bioinformatic analysis of differentially expressed microRNAs from cohorts one (n=48) and two (n=11) identified pathways associated with adrenergic stress and calcium dysregulation, rather than ischaemia. CONCLUSIONS: Circulating microRNAs associated with cardiac ischaemia were universally elevated in patients after surgery, independent of development of myocardial injury.

Resolvin D1 protects against sepsis-induced cardiac injury in mice.

Increased inflammation is the key mechanism that mediates sepsis induced cardiac injury. Resolvin D1 (RvD1), a bioactive lipid mediator synthesized from docosahexaenoic acid, can attenuate the severity of many inflammation-related diseases through anti-inflammatory and pro-resolving properties. However, the protective role of RvD1 in sepsis induced cardiac injury remains unclear. Mice were randomly divided into three groups: the control group, LPS group and RvD1 + LPS group. LPS (10 mg/kg, i.p.) was used to establish a sepsis-induced cardiac injury model. RvD1 (5 ug/kg, i.p.) was injected 30 min before LPS injection. RvD1 treatment significantly attenuated the deteriorated cardiac function and cardiac injury induced by LPS, as evidenced by the improved left ventricular ejection fraction, serum levels of cardiac injury markers and severity of cardiomyocyte apoptosis. In addition, RvD1 treatment significantly attenuated the infiltration of pro-inflammatory M1 macrophages and expression of inflammatory cytokines in the heart. Mechanistically, the attenuated activation of NK-κB and MAPK signaling mediated the anti-inflammatory and antiapoptotic effects of RvD1. In addition, LPS-induced infiltration of neutrophils and M1 macrophages in the spleen was significantly attenuated by the RvD1 treatment. Results of the present study suggest that RvD1 protects the heart against LPS-induced injuries by attenuating the local and systemic inflammatory response, highlighting the therapeutic effects of RvD1 in sepsis-induced cardiac injury.

TRPV1 activation mitigates hypoxic injury in mouse cardiomyocytes by inducing autophagy through the AMPK signaling pathway.

Autophagy is a highly conserved self-protection mechanism that plays a crucial role in cardiovascular diseases. Cardiomyocyte hypoxic injury promotes oxidative stress and pathological alterations in the heart, although the interplay between these effects remains elusive. The transient receptor potential vanilloid 1 (TRPV1) ion channel is a nonselective cation channel that is activated in response to a variety of exogenous and endogenous physical and chemical stimuli. Here, we investigated the effects and mechanisms of action of TRPV1 on autophagy in hypoxic cardiomyocytes. In this study, primary cardiomyocytes isolated from C57 mice were subjected to hypoxic stress, and their expression of TRPV1 and adenosine 5'-monophosphate-activated protein kinase (AMPK) was regulated. The autophagy flux was assessed by Western blotting and immunofluorescence staining, and the cell viability was determined through Cell counting kit-8 assay and Lactate dehydrogenase assays. In addition, the calcium influx after the upregulation of TRPV1 expression in cardiomyocytes was examined. The results showed that the number of autophagosomes in cardiomyocytes was higher under hypoxic stress and that the blockade of autophagy flux aggravated hypoxic damage to cardiomyocytes. Moreover, the expression of TRPV1 was induced under hypoxic stress, and its upregulation by capsaicin improved the autophagy flux and protected cardiomyocytes from hypoxic damage, whereas the silencing of TRPV1 significantly attenuated autophagy. Our observations also revealed that AMPK signaling was activated and involved in TRPV1-induced autophagy in cardiomyocytes under hypoxic stress. Overall, this study demonstrates that TRPV1 activation mitigates hypoxic injury in cardiomyocytes by improving autophagy flux through the AMPK signaling pathway and highlights TRPV1 as a novel therapeutic target for the treatment of hypoxic cardiac disease.

Adenoviral ßARKct Cardiac Gene Transfer Ameliorates Postresuscitation Myocardial Injury in a Porcine Model of Cardiac Arrest.

OBJECTIVE: The aim of the study was to determine whether the inhibition of the G-protein-coupled receptor kinase 2 by adenoviral ßARKct cardiac gene transfer can ameliorate postresuscitation myocardial injury in pigs with cardiac arrest (CA) and explore the mechanism of myocardial protection. METHODS: Male landrace domestic pigs were randomized into the sham group (anesthetized and instrumented, but ventricular fibrillation was not induced) (n = 4), control group (ventricular fibrillation 8 min, n = 8), and ßARKct group (ventricular fibrillation 8 min, n = 8). Hemodynamic parameters were monitored continuously. Blood samples were collected at baseline, 30 min, 2 h, 4 h, and 6 h after the return of spontaneous circulation (ROSC). Left ventricular ejection fraction was assessed by echocardiography at baseline and 6 h after ROSC. These animals were euthanized, and the cardiac tissue was removed for analysis at 6 h after ROSC. RESULTS: Compared with those in the sham group, left ventricular +dp/dtmax, -dp/dtmax, cardiac output (CO), and ejection fraction (EF) in the control group and the ßARKct group were significantly decreased at 6 h after the restoration of spontaneous circulation. However, the ßARKct treatment produced better left ventricular +dp/dtmax, -dp/dtmax, CO, and EF after ROSC. The ßARKct treatment also produced lower serum cardiac troponin I, CK-MB, and lactate after ROSC. Furthermore, the adenoviral ßARKct gene transfer significantly increased ß1 adrenergic receptors, SERCA2a, RyR2 levels, and decreased GRK2 levels compared to control. CONCLUSIONS: The inhibition of GRK2 by adenoviral ßARKct cardiac gene transfer can ameliorate postresuscitation myocardial injury through beneficial effects on restoring the sarcoplasmic reticulum Ca-handling proteins expression and upregulating the ß1-adrenergic receptor level after cardiac arrest.

miR-34b/c regulates doxorubicin-induced myocardial cell injury through ITCH.

Objective: To determine the underlying mechanism of miR-34b/c in regulating doxorubicin (Dox)-induced myocardial cell injury.Methods: The viability of mouse myocardial cells HL-1 was detected by MTT assay. The apoptosis of HL-1 cells was detected by TUNEL assay. mRNA expressions of ITCH, TNF-α and IL-6 were measured by qRT-PCR. Protein levels of ITCH, NF-κB, TNF-α and IL-6 were measured by western blot. Dual luciferase assay was performed to detect the regulation of miR-34b/c on ITCH. Mouse model of cardiomyopathy was induced by intraperitoneal injection of Dox.Results: Dox reduced HL-1 cell viability and activated NF-κB pathway in HL-1 cells. miR-34b/c expressions were gradually up-regulated and ITCH expression was gradually down-regulated in Dox-treated HL-1 cells. miR-34b/c expression had negative correlation with the mRNA expression of ITCH. Besides, ITCH was a target of miR-34b/c. miR-34b/c mimic reduced cell viability, suppressed ITCH expression, increased TNF-α and IL-6 level, and promoted NF-κB expression in nucleus and cytoplasm of HL-1 cells. Whereas silencing miR-34 protected HL-1 cells through regulating ITCH. Finally, we demonstrated miR-34 antagomir-protected myocardial cells in mouse model of cardiomyopathy.Conclusion: miR-34b/c decreased HL-1 cell viability and promoted the secretion of proinflammatory cytokines in Dox-induced myocardial cells through ITCH/NF-κB pathway.

Resveratrol attenuates pulmonary embolism associated cardiac injury by suppressing activation of the inflammasome via the MALAT1­miR­22­3p signaling pathway.

Resveratrol (RS) has been reported to prevent the development of cardiac injury induced by pulmonary embolism (PE). The present study aimed to explore the potential mechanism of RS involved in cardiac injury induced by PE. A luciferase assay was conducted to detect the effect of RS on promoter efficiency of metastasis associated lung adenocarcinoma transcript 1 (MALAT1), in­silico analysis and luciferase assays were performed to explore the regulatory relationship between MALAT1, microRNA (miR)­22­3p and NLRP3. Reverse transcription PCR, western blot analysis and ELISA were carried out to examine MALAT1, miR­22­3p, NLRP3, ASC, Caspase­1, interleukin (IL)­1ß and IL­18 among different animal model groups, including the sham group, PE associated cardiac injury group and PE associated cardiac injury plus RS group. The results revealed that RS downregulated promoter efficiency of MALAT1 and MALAT1 directly targeted miR­22­3p, and luciferase activity of MALAT1 was inhibited by miR­22­3p, and furthermore miR­22­3p inhibited the expression of NLRP3 by binding to complementary sequences in the 3' untranslated region of NLRP3. MALAT1, NLRP3, ASC, Caspase­1, IL­1ß and IL­18 levels were much increased, while miR­22­3p level was much decreased in PE associated cardiac injury group compared with the sham group, while the RS upon the PE associated cardiac injury group slightly reduced the upregulated MALAT1/NLRP3 level and elevated the downregulated miR­22­3p level. In conclusion, it was demonstrated that RS has been demonstrated to prevent the development of cardiac injury induced by PE via modulating the expression of MALAT1 and further affect miR­22­3p and NLRP3.

Changes of Metabolic Phenotype of Cardiac Progenitor Cells During Differentiation: Neutral Effect of Stimulation of AMP-Activated Protein Kinase.

Cardiac progenitor cells (CPCs) in the adult mammalian heart, as well as exogenous CPCs injected at the border zone of infarcted tissue, display very low differentiation rate into cardiac myocytes and marginal repair capacity in the injured heart. Emerging evidence supports an obligatory metabolic shift from glycolysis to oxidative phosphorylation (OXPHOS) during stem cells differentiation, suggesting that pharmacological modulation of metabolism may improve CPC differentiation and, potentially, healing properties. In this study, we investigated the metabolic transition underlying CPC differentiation toward cardiac myocytes. In addition, we tested whether activators of adenosine monophosphate-activated protein kinase (AMPK), known to promote mitochondrial biogenesis in other cell types would also improve CPC differentiation. Stem cell antigen 1 (Sca1+) CPCs were isolated from adult mouse hearts and their phenotype compared with more mature neonatal rat cardiac myocytes (NRCMs). Under normoxia, glucose consumption and lactate release were significantly higher in CPCs than in NRCMs. Both parameters were increased in hypoxia together with increased abundance of Glut1 (glucose transporter), of the monocarboxylic transporter Mct4 (lactate efflux mediator) and of Pfkfb3 (key regulator of glycolytic rate). CPC proliferation was critically dependent on glucose and glutamine availability in the media. Oxygen consumption analysis indicates that, compared with NRCMs, CPCs exhibited lower basal and maximal respirations with lower Tomm20 protein expression and mitochondrial DNA content. This CPC metabolic phenotype profoundly changed upon in vitro differentiation, with a decrease of glucose consumption and lactate release together with increased abundance of Tnnt2, Pgc-1α, Tomm20, and mitochondrial DNA content. Proliferative CPCs express both alpha1 and -2 catalytic subunits of AMPK that is activated by A769662. However, A769662 or resveratrol (an activator of Pgc-1α and AMPK) did not promote either mitochondrial biogenesis or CPC maturation during their differentiation. We conclude that although CPC differentiation is accompanied with an increase of mitochondrial oxidative metabolism, this is not potentiated by activation of AMPK in these cells.

miR-146a attenuates apoptosis and modulates autophagy by targeting TAF9b/P53 pathway in doxorubicin-induced cardiotoxicity.

Clinical therapy of doxorubicin (DOX) is limited due to its cardiotoxicity. miR-146a was proved as a protective factor in many cardiovascular diseases, but its role in chronic DOX-induced cardiotoxicity is unclear. The objective of this study was to demonstrate the role of miR-146a in low-dose long-term DOX-induced cardiotoxicity. Experiments have shown that DOX intervention caused a dose-dependent and time-dependent cardiotoxicity involving the increased of apoptosis and dysregulation of autophagy. The cardiotoxicity was inhibited by overexpressed miR-146a and was more severe when miR-146a was downgraded. Further research proved that miR-146a targeted TATA-binding protein (TBP) associated factor 9b (TAF9b), a coactivator and stabilizer of P53, indirectly destroyed the stability of P53, thereby inhibiting apoptosis and improving autophagy in cardiomyocytes. Besides, miR-146a knockout mice were used for in vivo validation. In the DOX-induced model, miR-146a deficiency made it worse whether in cardiac function, cardiomyocyte apoptosis or basal level of autophagy, than wild-type. In conclusion, miR-146a partially reversed the DOX-induced cardiotoxicity by targeting TAF9b/P53 pathway to attenuate apoptosis and adjust autophagy levels.

Effect of miR-26a on diabetic rats with myocardial injury by targeting PTEN.

OBJECTIVE: To investigate the effect of micro ribonucleic acid (miR)-26a on diabetes-induced myocardial injury in rats by targeting the gene of phosphate and tension homology detected on chromosome ten (PTEN). MATERIALS AND METHODS: Male Wistar rats aged 8-9 weeks old were divided into the control group (n=10), GK group (n=10), and miR-26a agomir group (n=10) according to the body weight. MiRanda and TargetScan target gene prediction software were used to predict and analyze the target gene of miR-26a-5p. The expressions of miR-26a and PTEN in the myocardial tissues of the diabetic rats were detected by quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR). Hematoxylin-eosin (HE) staining was adopted to observe the pathological changes in the myocardial tissues. In addition, the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was conducted to detect myocardial apoptosis, while the expression of PTEN protein was detected via immunohistochemistry, and the protein expressions of PTEN, b-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), and cysteinyl aspartate specific proteinase-3 (Caspase-3) were tested by Western blotting. RESULTS: TargetScan database analysis results showed that miR-26a-5p and PTEN 3'UTR had 6 pairs of complementary bases with the same sequence. Compared with those in the control group, the messenger RNA (mRNA) expression of PTEN in the GK group was notably increased (p<0.05), while that of miR-26a was substantially reduced (p<0.05). In comparison with those in the GK group, the mRNA expression of PTEN was significantly decreased, but that of miR-26a was significantly raised in miR-26a agomir group (p<0.05). Through observation under an optical microscope, it was manifested that in the control group, the myocardial fibers were intact with clear texture but no fracture, and the solid necrosis did not appear in myocardial cells. In the GK group, the myocardial fibers were disorderedly arranged and incomplete with an unclear edge and burrs. The myocardial fibers in the miR-26a agomir group were more regular, with less breakage and solid necrosis. According to TUNEL staining results, the TUNEL-stained brown granules in rats in the GK group were remarkably increased, relative to the control group (p<0.05). Compared with the GK group, miR-26a agomir group had markedly decreased the TUNEL-stained brown particles (p<0.05). It was found in immunohistochemical results that PTEN protein was in lighter color after staining in the control group, with a clear myocardial cell stripe structure. Compared with that in control group, PTEN protein in the GK group was in deeper color after staining, and in comparison with that in the GK group, the color of PTEN protein in miR-26a agomir group became significantly lighter. Moreover, the Western blotting results demonstrated that, compared with those in the control group, the Caspase-3 and Bax protein expressions in the GK group were significantly raised, while Bcl-2 protein expression was notably reduced (p<0.05). Besides, in comparison with the GK group, miR-26a agomir group evidently elevated Caspase-3 and Bax protein expressions and a notably increased Bcl-2 protein expression (p<0.05). CONCLUSIONS: We showed that miR-26a can protect against myocardial injury in diabetic rats by regulating PTEN.