Zhinong Wang

MiR-204 regulates cardiomyocyte autophagy induced by ischemia-reperfusion through LC3-II.

BackgroundAutophagy plays a significant role in myocardial ischemia-reperfusion (IR) injury. So it is important to inhibit autophagy to protect cardiomyocytes besides anti-apoptosis. MiRNA has been demonstrated to protect cardiomyocytes against apoptosis during IR, while whether it has anti-autophagy effect has not been known. The aim of this study was to investigate whether miR-204 regulated autophagy by regulating LC3-II protein, which is the marker of autophagosome during myocardial IR injury.MethodsAdult SD rats were randomized to Control and IR groups. IR group was treated with 30 min ischemia by ligating the left anterior descending coronary artery, followed by 2 h reperfusion by loosing the ligation. The expression of miR-204 was measured by RT-PCR, and LC3 protein was measured by western-blot.ResultsWe found that IR induced cardiomyocytes autophagy, together with down-regulation of miR-204 and up-regulation of LC3-II protein. And, we have found that LC3-II protein was regulated by miR-204, using the method of transferring miR-204 mimic or AMO-204 into the cardiomyocytes, before.ConclusionsThese studies provided evidence that miR-204 played an important role in regulating autophagy through LC3-IIprotein during IR.

Anti-inflammatory effect of hydrogen-rich saline in a rat model of regional myocardial ischemia and reperfusion

INTRODUCTION To study the possible anti-inflammatory effect of hydrogen-rich saline (H(2) saline) on rat hearts with regional myocardial ischemia and reperfusion (I/R). METHODS Sixty-six rats were equally randomized to three groups: sham-operated group, I/R group (control group) and I/R plus H(2) saline treatment group. Myocardial I/R was established by occlusion of the left anterior descending (LAD) coronary artery for 30 min and reperfusion for 24 h. RESULTS H(2) saline treatment attenuated I/R-induced cardiac cell apoptosis, presenting as significant improvement of heart function parameters 24h after reperfusion, including left ventricular systolic pressure (LVSP), left ventricular diastolic pressure (LVEDP), +(dP/dt)max and -(dP/dt)max. It also decreased neutrophil infiltration, 3-nitrotyrosine level, expression of intercellular adhesion molecule 1(ICAM-1) and myeloperoxidase (MPO) activity in the area at risk zones (AAR) of rat hearts subjected to regional myocardial I/R, and attenuated the increase of I/R induced proinflammatory cytokine tumor necrosis factor-α (TNF-a) and interleukin-1β (IL-1b) levels in the AAR. CONCLUSION H(2) saline has an anti-inflammatory effect on rat hearts with regional myocardial I/R.

Hydrogen Sulfide Attenuates Myocardial Hypoxia-Reoxygenation Injury by Inhibiting Autophagy via mTOR Activation.

Background: Autophagy plays a significant role in myocardial ischemia reperfusion (IR) injury. Hydrogen sulfide (H2S) has been demonstrated to protect cardiomyocytes against IR injury, while whether it has anti-autophagy effect has not been known. The aim of this study was to investigate whether H2S regulates autophagy during IR injury and its possible mechanism. Methods and Results: The cardiomyocytes of neonatal rats were randomized into Con, hypoxia-reoxygenation (HR) and H2S protection groups. The severity of cell injury was evaluated by cell vitality (MTT) and lactate dehydrogenase (LDH) release assays, and autophagy level was evaluated by flow cytometry and the assessment of autophagy-related gene (Atg) expression, such as that of Beclin1 and LC3-II. In response to H2S, Beclin1 and LC3-II protein were found to be down-regulated and p-mTOR protein was found to be up-regulated, together with an increase in cell vitality and a decrease in LDH. Furthermore, to find out whether mTOR was involved in the protective effect of H2S, rapamycin, inhibiter of mTOR, was used with or without applying NaHS and HR. It was found that rapamycin attenuated the myocardiocyte protective effect of H2S. To demonstrate the effect of autophagy during HR injury, the cardiomyocytes were pre-treated with 3-MA, which is an autophagy inhibitor, cell injury was attenuated by 3-MA. Conclusions: H2S plays a myocardial protective role against IR injury by regulating autophagy via mTOR activation.

Involvement of miR-1 in the protective effect of hydrogen sulfide against cardiomyocyte apoptosis induced by ischemia/reperfusion

The protective effect of hydrogen sulfide (H2S) against myocardial ischemia/reperfusion (IR) injury via anti-apoptotic signaling is well established, but the underlying mechanism remains unclear. Recently, miRNAs have been identified as important mediators of myocardial injury by regulating apoptosis-related genes. It was found in our previous preliminary study that microRNA-1 (miR-1) expression underwent a significant change in IR group compared to H2S preconditioned group, indicating that miR-1 possessed myocyte-specific properties. In the present study, we intended to see whether miR-1 participated in H2S protection of cardiomyocytes against IR-induced apoptosis by regulating apoptosis-related genes. Cardiomyocytes of neonatal rats were subjected to hypoxia/reoxygenation (HR) injury with or without H2S preconditioning, while the myocardium of adult SD rats was subjected to IR with or without H2S preconditioning. It was found that HR injury increased apoptosis of cardiac myocytes, up-regulated the expression of miR-1, and down-regulated the expression of Bcl-2. H2S preconditioning attenuated cardiomyocyte apoptosis and LDH release, as well as enhanced cell viability following HR injury. MiR-1 was up-regulated by HR and down-regulated by H2S preconditioning. In contrast, Bcl-2 was down-regulated by HR and up-regulated by H2S preconditioning. In addition, Bcl-2 protein was down-regulated by the miR-1 mimic in a dose-dependent manner. H2S also attenuated IR-induced cardiomyocyte apoptosis in vivo. MiR-1 regulated H2S protection of cardiomyocytes against IR-induced apoptosis by stimulating Bcl-2. These results implicate miR-1 as an important regulator of H2S on the IR myocardium.

PI3K/SGK1/GSK3β signaling pathway is involved in inhibition of autophagy in neonatal rat cardiomyocytes exposed to hypoxia/reoxygenation by hydrogen sulfide.

Excessive autophagy aggravates myocardial ischemia/reperfusion (IR) injury. Hydrogen sulfide (H2S) has been shown to possess a strong cardioprotective effect due to its anti-necrosis, anti-apoptosis, anti-oxidant and anti-inflammatory properties. Our previous study showed that H2S could also protect the myocardium against IR injury through its anti-autophagy effect in vivo, but the underlying mechanism remains unclear. The aim of the present study was to determine whether PI3K/SGK1/GSK3β signaling pathway was involved in the anti-autophagy effect of H2S against myocardial hypoxia/reoxygenation (HR) injury in vitro. Autophagy was significantly increased in cardiomyocytes subjected to HR, but it was down-regulated by H2S (NaHS donor). Blocking PI3K by LY294002 (a PI3K inhibitor) or knocking down SGK1 by SGK1 siRNA augmented autophagy and attenuated the anti-autophagy effect of H2S. However, blocking GSK3β by tws119 (a GSK3β inhibitor) produced an opposite effect. In addition, while treatment of neonatal rat cardiomyocytes with HR reduced cell viability and augmented cell injury, H2S significantly reversed it. Blocking PI3K or knocking down SGK1 aggravated HR injury and weakened the protective effect of H2S, while blocking GSK3β produced an opposite effect. In conclusion, H2S can inhibit autophagy in neonatal rat cardiomyocytes exposed to H/R and exert a cardioprotective effect at least partly by regulating PI3K/SGK1/GSK3β signaling pathway.

Indexed effective orifice area is a significant predictor of higher mid- and long-term mortality rates following aortic valve replacement in patients with prosthesis-patient mismatch

Prosthesis-patient mismatch (PPM) is defined as a too-small effective orifice area (EOA) of an inserted prosthetic relative to body size, resulting in an abnormally high postoperative gradient. It is unclear, however, whether residual stenosis after aortic valve replacement (AVR) has a negative impact on mid- and long-term survivals. We searched electronic databases, including PubMed, Embase, Medline and the Cochrane controlled trials register, through October 2012, to identify published full-text English studies on the association between PPM and mortality rates. A significant PPM was defined as an indexed EOA (iEOA)<0.85 cm2/m2, and severe PPM as an iEOA<0.65 cm2/m2. Two reviewers independently assessed the studies for inclusion and extracted data. Fourteen observational studies, involving 14 874 patients, met our final inclusion criteria. Meta-analysis demonstrated that PPM significantly increased mid-term (odds ratio [OR] 1.42, 95% confidence interval [CI] 1.19-1.69) and long-term (OR 1.52, 95% CI 1.26-1.84) all-cause mortalities. Subgroup analysis showed that PPM was associated with higher mid- and long-term mortality rates only in younger and predominantly female populations. Risk-adjusted sensitivity analysis showed that severe PPM was associated with reduced survival (adjusted hazard ratio [HR] 1.50, 95% CI 1.24-1.80), whereas moderate PPM was not (adjusted HR 0.96, 95% CI 0.86-1.07). Regardless of severity, however, PPM had a negative effect on survival in patients with impaired ejection fraction (adjusted HR 1.26, 95% CI 1.09-1.47). PPM (iEOA<0.85 cm2/m2) after AVR tended to be associated with increased long-term all-cause mortality in younger patients, females and patients with preoperative left ventricular dysfunction. Severe PPM (iEOA<0.65 cm2/m2) was a significant predictor of reduced long-term survival in all populations undergoing AVR.

Estrogens protect myocardium against ischemia/reperfusion insult by up-regulation of CRH receptor type 2 in female rats

BACKGROUND The mechanism underlying estrogen cardioprotection remains largely unknown. Urocortin (UCN), a member of corticotropin-releasing hormone (CRH) family, is one of endogenous cardioprotective factors. The goal of present study is to investigate whether estrogens regulate UCN and its receptor CRH receptor type 2 (CRHR2) in female rat heart. METHODS 17β-estradiol (E2) was subcutaneously administrated to ovariectomized (OVX) rats for eight weeks. UCN was administrated before simulated myocardial ischemia/reperfusion (I/R). Cell damage was assessed by measurement of infarct size, activity of serum creatine kinase (CK) and lactate dehydrogenase (LDH) and percentage of TUNEL staining in myocardium. The mRNA and protein levels of UCN and CRHR2 were determined in sham operated and OVX rats with or without E2 replacement. DNA methylation frequency of CRHR2 gene promoter was determined by bisulfite-sequencing. RESULTS UCN administration reduced infarct size, LDH and CK level and percentage of TUNEL staining upon I/R injury. The cardioprotective effects of UCN were abrogated in OVX rats and E2 replacement restored UCN-induced cardioprotection.CRHR2 mRNA and protein expression were down-regulated more than 40% in OVX rats, both of which were restored by E2 replacement. UCN mRNA and protein levels were not affected by ovariectomy and E2 replacement. Hypermethylation in CRHR2 promoter was found in OVX rats, and two of the methylated CpG sites were seated at cis-acting elements. Hypermethylation induced by OVX could also be ameliorated by E2 replacement. CONCLUSION Estrogens maintain CRHR2 expression in myocardium, which may through an epigenetic mechanism, and enhance UCN-induced cardioprotective effects against I/R injury.

Risk Factors for Embolism in Cardiac Myxoma: A Retrospective Analysis

Background Myxomas are the most common primary heart tumors and are closely associated with embolic events. Cardiac myxomas typically arise from the interatrial septum at the border of the fossa ovalis in the left atrium. Any other location is considered atypical. Embolism, one of the complications of myxoma, is associated with high morbidity and mortality. The aim of this study was to investigate the risk factors for embolism in patients with cardiac myxoma. Material/Methods In this retrospective study, a cohort of 162 patients with cardiac myxomas was surgically treated between January 1998 and June 2014 at 3 cardiac centers in China. Preoperative data, including platelet count, sex, age, and the tumor (size, location, surface, and attachment), were compared between embolic and non-embolic groups of patients. Results No significant differences in vascular risk factors were seen between the 2 groups. However, the percentage of higher platelet count (>300×109/L) and mean platelet volume in the embolic group were significantly higher than in the non-embolic group (P=0.0356, and 0.0113, respectively). Irregular surface and atypical location of the myxomas were also independently associated with increased risk of embolic complications. Conclusions Tumor location, macroscopic appearance, mean platelet volume, and high platelet count are strong risk factors for embolic events in patients with cardiac myxomas.

Hydrogen Sulfide Protects Cardiomyocytes against Apoptosis in Ischemia/Reperfusion through MiR-1-Regulated Histone Deacetylase 4 Pathway

Background/Aims: Hydrogen sulfide (H2S) is a powerful inhibitor of cardiomyocytes apoptosis following ischemia/reperfusion (IR) injury, but the underlying mechanism remains unclear. Our previous study showed that microRNA-1 (miR-1) was upregulated by 2.21 fold in the IR group compared with that in the H2S preconditioned group. MiR-206 affected the process of cardiomyocytes hypertrophy by regulating histone deacetylase 4 (HDAC4). HDAC4 is also known to play an anti-apoptotic role in tumor cells, but its role in the myocardium has not been reported. The aim of this study was to test whether H2S could inhibit apoptosis of cardiomyocytes through HDAC4 regulation by miR-1 in IR. Methods: Cardiomyocytes of neonatal rats were subjected to hypoxia/reoxygenation (HR) injury with or without H2S pretreatment to simulate IR injury Cardiomyocytes were transfected with miR-1 mimic or HDAC4 siRNA to evaluate whether the miR-1-HDAC4 signaling pathway was involved in the protective effect of H2S. Results: HR increased cell apoptosis and caspase-3 cleavage, upregulated miR-1, and downregulated HDAC4. H2S preconditioning attenuated the apoptosis of cardiomyocytes, caspase-3 cleavage and LDH release, and enhanced cell viability In addition, H2S downregulated miR-1, and preserved HDAC4 expression. HDAC4 protein was down-regulated by miR-1 mimic. Transfection of cardiomyocytes with miR-1 mimic partially reduced the protective effect of H2S. Meanwhile, transfection of cardiomyocytes with siRNA to HDAC4 partially abrogated the protective effect of H2S. Conclusions: The miR-1-HDAC4 signaling pathway is involved in the protective effect of H2S against the apoptosis of cardiomyocytes during the IR injury process.

Treating cardiac myxomas: a 16-year Chinese single-center study.

Aims Currently, myxoma is the most common type of primary cardiac tumor diagnosed. This article describes the experience over the past 16 years with cases of cardiac myxoma in Chinese patients and elucidated the differences between solid and papillary myxomas. Methods The clinical details of 68 patients with cardiac myxomas who underwent surgery between January 1996 and January 2012 at our center were retrospectively analyzed. Results The left atrium was the primary tumor site in 88% of the patients included in this study. The most common implant site was the interatrial septum (69%), especially for patients with solid tumors. Common clinical symptoms included dyspnea and palpitation, whereas embolic events occurred in 12 patients. Myxoma resection involved a midline sternotomy utilizing cardiopulmonary bypass. According to pathological classification, solid myxomas were present in 28 patients (47%), whereas papillary myxomas were detected in 40 patients (53%). In the solid group, arrhythmias and a larger tumor volume were more common. Correspondingly, in 97.4 ± 2.5% of cases, secondary surgery was not needed after 10 years. Overall, the actuarial survival for patients undergoing surgical excision of myxoma was 98.4 ± 1.6% at 5 years and 96.0 ± 2.8% at 10 years. Conclusion Solid myxomas were associated with more arrhythmias, a larger tumor volume, implantation in the interatrial septum, and a need for concomitant surgery compared with papillary myxomas. Further studies should determine whether serum or histological markers could be routinely used in combination with echocardiograms, MRI and computed tomography for the predictions of recurrent myxomas during annual follow-up examinations.