杨梅素对小鼠梗死后心肌重塑和心力衰竭的影响及机制

目的:探讨杨梅素对小鼠梗死后心肌重塑和心力衰竭的影响及调控机制。方法:结扎左冠状动脉前降支建立心肌梗死的模型,将雄性C57/BL6J小鼠随机分为3组(每组20只):假手术组、心肌梗死组、心肌梗死+杨梅素组。心肌梗死+杨梅素组给予杨梅素250 mg/kg/d灌胃,假手术组和心肌梗死组给予同体积5%羧甲基纤维素钠灌胃。药物治疗1月后,小鼠心脏超声检测心功能;Masson染色评估胶原容积分数(collagen volume fraction,CVF);电镜检测心肌线粒体损伤;Western blot检测p-Mst1、LC3和p62的表达。结果:与假手术组相比,心肌梗死组心功能显著降低(P0.05),心肌ANP和BNP mRNA水平显著增高(P0.05),CVF显著增高(P0.05),线粒体明显肿胀,p-Mst1表达和LC3Ⅱ/LC3Ⅰ比率显著增高(P0.05),p62表达显著降低(P0.05);与心肌梗死组相比,心功能显著增加(P0.05),心肌ANP和BNP mRNA水平显著降低(P0.05),CVF显著降低(P0.05),线粒体超微结构有显著改善,p-Mst1、p62表达显著降低(P0.05),LC3Ⅱ/LC3Ⅰ比率显著增高(P0.05)。结论:杨梅素可能通过抑制Mst1减轻小鼠梗死后心肌重塑和心力衰竭。     

Luteolin alleviates post‐infarction cardiac dysfunction by up‐regulating autophagy through Mst1 inhibition

Myocardial infarction (MI), which is characterized by chamber dilation and LV dysfunction, is associated with substantially higher mortality. We investigated the effects and underlying mechanisms of Luteolin on post‐infarction cardiac dysfunction. Myocardial infarction was constructed by left anterior descending coronary artery ligation. In vitro, cultured neonatal cardiomyocytes subjected to simulated MI were used to probe mechanism. Luteolin significantly improved cardiac function, decreased cardiac enzyme and inflammatory cytokines release after MI. Enhanced autophagic flux as indicated by more autophagosomes puncta, less accumulation of aggresomes and P62 in the neonatal cardiomyocytes after hypoxia was observed in the Luteolin pre‐treatment group. Western blot analysis also demonstrated that Luteolin up‐regulated autophagy in the cardiomyocytes subjected to simulated MI injury. Furthermore, Luteolin increased mitochondrial membrane potential, adenosine triphosphate content, citrate synthase activity and complexes I/II/III/IV/V activities in the cardiomyocytes subjected to simulated MI injury. Interestingly, mammalian sterile 20‐like kinase 1 (Mst1) knockout abolished the protective effects of Luteolin administration. Luteolin enhances cardiac function, reduces cardiac enzyme and inflammatory markers release after MI. The protective effects of Luteolin are associated with up‐regulation of autophagy and improvement of mitochondrial biogenesis through Mst1 inhibition.     

Melatonin activates Parkin translocation and rescues the impaired mitophagy activity of diabetic cardiomyopathy through Mst1 inhibition

Mitophagy eliminates dysfunctional mitochondria and thus plays a cardinal role in diabetic cardiomyopathy (DCM). We observed the favourable effects of melatonin on cardiomyocyte mitophagy in mice with DCM and elucidated their underlying mechanisms. Electron microscopy and flow cytometric analysis revealed that melatonin reduced the number of impaired mitochondria in the diabetic heart. Other than decreasing mitochondrial biogenesis, melatonin increased the clearance of dysfunctional mitochondria in mice with DCM. Melatonin increased LC3 II expression as well as the colocalization of mitochondria and lysosomes in HG‐treated cardiomyocytes and the number of typical autophagosomes engulfing mitochondria in the DCM heart. These results indicated that melatonin promoted mitophagy. When probing the mechanism, increased Parkin translocation to the mitochondria may be responsible for the up‐regulated mitophagy exerted by melatonin. Parkin knockout counteracted the beneficial effects of melatonin on the cardiac mitochondrial morphology and bioenergetic disorders, thus abolishing the substantial effects of melatonin on cardiac remodelling with DCM. Furthermore, melatonin inhibited Mammalian sterile 20‐like kinase 1 (Mst1) phosphorylation, thus enhancing Parkin‐mediated mitophagy, which contributed to mitochondrial quality control. In summary, this study confirms that melatonin rescues the impaired mitophagy activity of DCM. The underlying mechanism may be attributed to activation of Parkin translocation via inhibition of Mst1.     

Exosomal Mst1 transfer from cardiac microvascular endothelial cells to cardiomyocytes deteriorates diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is characterized by cardiac microvascular endothelial cells (CMECs) injury and cardiomyocyte (CM) dysfunction. Exosomes mediated cellular communication between CMECs and CM has emerging roles in the pathogenesis of DCM, but the underlining mechanisms are unclear. Mammalian sterile 20-like kinase 1 (Mst1), a key component in Hippo pathway which participates in regulating organ size, apoptosis and autophagy, is involved in the development of DCM. We generated the endothelial-specific Mst1 transgenic mice (Tg-Mst1^EC) and constructed diabetic model with streptozotocin (STZ). Interestingly, Tg-Mst1^EC mice suffered from worse cardiac function and aggravated insulin resistance compared with non-transgenic (NTg) diabetic mice. The content of Mst1 protein was increased, while Mst1 mRNA had no significant change in CM isolated from diabetic Tg-Mst1^EC mice. In vitro, CMECs-derived exosomes were taken up by CM and increased Mst1 protein content which inhibited autophagy, as well as enhanced apoptosis in high glucose (HG) cultured CM as evidenced by immunofluorescence and western blot analysis. In addition, Mst1 inhibited glucose uptake under diabetic condition by disrupting the glucose transporter type 4 (GLUT4) membrane translocation through decreasing the interaction between Daxx and GLUT4, as well as enhancing the association of Mst1 and Daxx. Our study exemplifies pleiotropic effects of Mst1-enriched exosomes released from CMECs on inhibiting autophagy, promoting apoptosis and suppressing the glucose metabolism in CM.     

Downregulation of SOK1 promotes the migration of MCF-7 cells

SOK1 is a member of the germinal center kinase (GCK-III) subfamily but little is known about it, particularly with respect to its role in signal transduction pathways relative to tumor metastasis. By stably transfecting SOK1 siRNA into the MCF-7 breast cancer cell line we found that SOK1 promotes the migration of MCF-7 cells, as determined using wound-healing and Boyden chamber assays. However, cell proliferation assays revealed that silencing SOK1 had no effect on cell growth relative to the normal cells. Silencing SOK1 also had an effect on the expression and phosphorylation status of a number of proteins in MCF-7 cells, including FAK and GM130, whereby a decrease in SOK1 led to an increase in the expression of these proteins.     

Mammalian Ste20-like kinase 1 inhibition as a cellular mediator of anoikis in mouse bone marrow mesenchymal stem cells

BACKGROUND The low survival rate of mesenchymal stem cells(MSCs) caused by anoikis, a form of apoptosis, limits the therapeutic efficacy of MSCs. As a proapoptotic molecule, mammalian Ste20-like kinase 1(Mst1) can increase the production of reactive oxygen species(ROS), thereby promoting anoikis. Recently, we found that Mst1 inhibition could protect mouse bone marrow MSCs(mBMSCs) from H2O2-induced cell apoptosis by inducing autophagy and reducing ROS production. However, the influence of Mst1 in...     

Effects of G-CSF on cardiac remodeling after acute myocardial infarction in swine

We examined whether granulocyte colony-stimulating factor (G-CSF) prevents cardiac dysfunction and remodeling after myocardial infarction (MI) in large animals. MI was produced by ligation of left anterior descending coronary artery in swine. G-CSF (10 microg/kg/day, once a day) was injected subcutaneously from 24h after ligation for 7 days. Echocardiographic examination revealed that the G-CSF treatment induced improvement of cardiac function and attenuation of cardiac remodeling at 4 weeks after MI. In the ischemic region, the number of apoptotic endothelial cells was smaller and the number of vessels was larger in the G-CSF treatment group than in control group. Moreover, vascular endothelial growth factor was more abundantly expressed and Akt was more strongly activated in the ischemic region of the G-CSF treatment group than of control group. These findings suggest that G-CSF prevents cardiac dysfunction and remodeling after MI in large animals.     

Hydrogen sulfide mitigates cardiac remodeling during myocardial infarction via improvement of angiogenesis

Exogenous hydrogen sulfide (H2S) leads to down-regulation of inflammatory responses and provides myocardial protection during acute ischemia/reperfusion injury; however its role during chronic heart failure (CHF) due to myocardial infarction (MI) is yet to be unveiled. We previously reported that H2S inhibits antiangiogenic factors such, as endostatin and angiostatin, but a little is known about its effect on parstatin (a fragment of proteinase-activated receptor-1, PAR-1). We hypothesize that H2S inhibits parstatin formation and promotes VEGF activation, thus promoting angiogenesis and significantly limiting the extent of MI injury. To verify this hypothesis MI was created in 12 week-old male mice by ligation of left anterior descending artery (LAD). Sham surgery was performed except LAD ligation. After the surgery mice were treated with sodium hydrogen sulfide (30 μmol/l NaHS, a donor for H2S, in drinking water) for 4 weeks. The LV tissue was analyzed for VEGF, flk-1 and flt-1, endostatin, angiostatin and parstatin. The expression of VEGF, flk-1 and flt-1 were significantly increased in treated mice while the level of endostatin, angiostatin and parstatin were decreased compared to in untreated mice. The echocardiography in mice treated with H2S showed the improvement of heart function compared to in untreated mice. The X-ray and Doppler blood flow measurements showed enhancement of cardiac-angiogenesis in mice treated with H2S. This observed cytoprotection was associated with an inhibition of anti-angiogenic proteins and stimulation of angiogenic factors. We established that administration of H2S at the time of MI ameliorated infarct size and preserved LV function during development of MI in mice. These results suggest that H2S is cytoprotective and angioprotective during evolution of MI.     

LOX-1 pathway affects the extent of myocardial ischemia-reperfusion injury

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) was originally identified as a receptor for oxidized low-density lipoprotein predominantly expressed in endothelial cells. LOX-1 expression can be induced in cardiomyocytes and that activation of LOX-1 is involved in apoptosis. To investigate possible roles of LOX-1 in myocardial ischemia-reperfusion injury, rats were subjected to coronary artery ligation for 1h followed by reperfusion for 2h. Immunohistochemistry revealed that expression of LOX-1 in cardiac myocytes was induced following ischemia-reperfusion but not ischemia alone. Administration of anti-LOX-1 monoclonal antibody resulted in a nearly 50% reduction in myocardial infarction size compared with that of normal IgG or saline (P<0.05). These findings suggest that activation of the LOX-1 pathway is involved in determining the extent of myocardial ischemia-reperfusion injury and that inhibition of the LOX-1 pathway may provide a novel strategy for treatment of acute myocardial infarction in humans.     

Insulin inhibits myocardial ischemia-induced apoptosis and alleviates chronic adverse changes in post-ischemic cardiac structure and function

Insulin has been shown to possess significant anti-apoptotic effect in myocardial ischemia/reperfusion (MI/R). However, the contribution by this protection of insulin to the prolonged cardiac function in rats subjected to ischemia remains unclear. The present study attempted to test whether early insulin treatment influences adverse prolonged post-ischemic cardiac structural and functional changes. Adult male rats were subjected to left anterior descending coronary artery occlusion and were randomized to receive one of the following treatments: saline (4 ml/kg/h i.v. injection beginning 10 min before the ischemia and continuing for 2 h), insulin (60 U/l, i.v. injection following the same routine, and hypodermic injection of insulin (0.5 U/ml, 1 ml/kg/d) for 3 days after the ischemia surgery) or insulin plus wortmannin (15 μg/kg i.v. injection 15 min before each insulin administration). Treatment with insulin significantly reduced infarct size, decreased plasma creatine kinase and lactate dehydrogenase activities, decreased apoptosis index and caspase-3 activity (all P < 0.01 vs. saline), and improved cardiac function 24 h after ischemia. Importantly, at the end of 4 weeks after the ischemia surgery, MI rats receiving insulin treatment showed smaller left ventricle (LV) cavity and thicker systolic interventricular septum, and increased cardiac ejection fraction and LV fractional shortening (all P < 0.05 vs. saline). Inhibition of insulin signaling with wortmannin not only blocked insulin’s anti-apoptotic effect, but also almost completely abolished effects of insulin on cardiac structure and function. These data indicate that inhibition of apoptosis by early insulin treatment alleviates chronic adverse changes in post-ischemic cardiac structure and function. Wenjuan Xing and Wenjun Yan contributed equally to this study.     

Distinct lipidomic profiles in models of physiological and pathological cardiac remodeling,and potential therapeutic strategies

Cardiac myocyte membranes contain lipids which remodel dramatically in response to heart growth and remodeling. Lipid species have both structural and functional roles. Physiological and pathological cardiac remodeling have very distinct phenotypes, and the identification of molecular differences represent avenues for therapeutic interventions. Whether the abundance of specific lipid classes is different in physiological and pathological models was largely unknown. The aim of this study was to determine whether distinct lipids are regulated in settings of physiological and pathological remodeling, and if so, whether modulation of differentially regulated lipids could modulate heart size and function. Lipidomic profiling was performed on cardiac-specific transgenic mice with 1) physiological cardiac hypertrophy due to increased Insulin-like Growth Factor 1 (IGF1) receptor or Phosphoinositide 3-Kinase (PI3K) signaling, 2) small hearts due to depressed PI3K signaling (dnPI3K), and 3) failing hearts due to dilated cardiomyopathy (DCM). In hearts of dnPI3K and DCM mice, several phospholipids (plasmalogens) were decreased and sphingolipids increased compared to mice with physiological hypertrophy. To assess whether restoration of plasmalogens could restore heart size or cardiac function, dnPI3K and DCM mice were administered batyl alcohol (BA; precursor to plasmalogen biosynthesis) in the diet for 16 weeks. BA supplementation increased a major plasmalogen species (p18:0) in the heart but had no effect on heart size or function. This may be due to the concurrent reduction in other plasmalogen species (p16:0 and p18:1) with BA. Here we show that lipid species are differentially regulated in settings of physiological and pathological remodeling. Restoration of lipid species in the failing heart warrants further examination.     

去势对离体大鼠心脏缺血/再灌注心功能及心肌凋亡的影响

目的:观察去势对离体大鼠心脏缺血／再灌注心脏功能和心肌凋亡的影响。方法:SD大鼠28只,随机分为去势组、对照组,每组14只。制备大鼠离体缺血／再灌注模型(缺血30min,再灌注2h),观察左室压力,再灌注结束后检测心肌梗死率和细胞凋亡指数,免疫组化技术检测心肌组织的Bcl-2、Bax水平。结果:(1)与对照组相比,去势组再灌注后的心脏左室收缩及舒张功能无显著变化(P>0．05);(2)去势组心肌梗死范围(43．68±6．89％)较对照组(39．33±7．85％)增加,但无统计学差异;(3)对照组和去势组间心肌细胞凋亡指数无统计学差异(P>0．05),心肌组织中Bcl-2、Bax含量未见显著变化。结论:去势对心脏缺血／再灌注心脏功能没有保护作用,而且不影响心肌细胞凋亡过程,生理剂量的雄激素对缺血再灌注后的心脏功能不产生损害作用。     

Sfrp1通过阻断Wnt信号通路减轻血管紧张素Ⅱ诱导的心脏损伤并促进自噬的研究

摘要 目的：本研究旨在评估Sfrp1在血管紧张素II诱导的心肌肥厚中的心脏保护作用，并探讨其与自噬和Wnt信号通路相关的可能机制。方法：利用重组AAV9载体将Sfrp1导入Ang II诱导的肥厚型H9C2心肌细胞。用CCK8测定细胞活力。流式细胞仪检测细胞凋亡率。用显微照片记录肥厚细胞大小的变化。western blot检测Sfrp1、Bcl-2、Bax、CytC、Caspase-3、P62、ATG5、Beclin、LC3、β-catenin和DVL1的蛋白表达。通过qRT-PCR检测β-连环蛋白和DVL1的mRNA表达。自噬抑制剂3-MA也用于验证治疗过程中自噬的参与。结果：（1）Sfrp1成功转染H9C2细胞，其过度表达减轻了心肌肥厚。（2）经过AAV9-Sfrp1预处理可减少肥厚心肌的细胞凋亡，可逆转Ang II组自噬相关蛋白（p62、ATG5、Beclin、LC3）的表达；（3）自噬在治疗心肌肥厚过程中的作用通过可自噬抑制剂3-MA来证实。（4）激活的Wnt信号（β-连环蛋白，DVL1）也被AAV9-Sfrp1抑制。结论：Sfrp1通过Wnt信号通路促进细胞自噬，从而保护心肌细胞免受肥厚性损伤和凋亡，这为Sfrp1对心肌肥厚的心肌保护作用机制提供了一个重要的视角。     

LncRNA SNHG1 promotes sepsis‐induced myocardial injury by inhibiting Bcl‐2 expression via DNMT1

Myocardial injury is a frequently occurring complication of sepsis. This study aims to investigate the molecular mechanism of long noncoding RNA (lncRNA) small nucleolar RNA host gene 1 (SNHG1)‐mediated DNA methyltransferase 1/B‐cell lymphoma‐2 (DNMT1/Bcl‐2) axis in sepsis‐induced myocardial injury. Mice and HL‐1 cells were treated with lipopolysaccharide (LPS) to establish animal and cellular models simulating sepsis and inflammation. LncRNA SNHG1 was screened out as a differentially expressed lncRNA in sepsis samples through microarray profiling, and the upregulated expression of lncRNA SNHG1 was confirmed in myocardial tissues of LPS‐induced septic mice and HL‐1 cells. Further experiments suggested that silencing of lncRNA SNHG1 reduced the inflammation and apoptotic rate of LPS‐induced HL‐1 cells. LncRNA SNHG1 inhibited Bcl‐2 expression by recruiting DNMT1 to Bcl‐2 promoter region to cause methylation. Inhibition of Bcl‐2 promoter methylation reduced the inflammation and apoptotic rate of LPS‐induced HL‐1 cells. In vivo experiments substantiated that lncRNA SNHG1 silencing alleviated sepsis‐induced myocardial injury in mice. Taken together, lncRNA SNHG1 promotes LPS‐induced myocardial injury in septic mice by downregulating Bcl‐2 through DNMT1‐mediated Bcl‐2 methylation.     

BI1 alleviates cardiac microvascular ischemia-reperfusion injury via modifying mitochondrial fission and inhibiting XO/ROS/F-actin pathways

Pathogenesis of cardiac microvascular ischemia-reperfusion (IR) injury is associated with excessive mitochondrial fission. However, the upstream mediator of mitochondrial fission remains obscure. Bax inhibitor 1 (BI1) is linked to multiple mitochondrial functions, and there have been no studies investigating the contribution of BI1 on mitochondrial fission in the setting of cardiac microvascular IR injury. This study was undertaken to establish the action of BI1 on the cardiac microvascular reperfusion injury and figure out whether BI1 sustained endothelial viability via inhibiting mitochondrial fission. Our observation indicated that BI1 was downregulated in reperfused hearts and overexpression of BI1 attenuated microvascular IR injury. Mechanistically, reperfusion injury elevated the levels of xanthine oxidase (XO), an effect that was followed by increased reactive oxygen species (ROS) production. Subsequently, oxidative stress mediated F-actin depolymerization and the latter promoted mitochondrial fission. Aberrant fission caused mitochondrial dysfunction and ultimately activated mitochondrial apoptosis in cardiac microvascular endothelial cells. By comparison, BI1 overexpression repressed XO expression and thus neutralized ROS, interrupting F-actin-mediated mitochondrial fission. The inhibitory effect of BI1 on mitochondrial fission sustained endothelial viability, reversed endothelial barrier integrity, attenuated the microvascular inflammation response, and maintained microcirculation patency. Altogether, we conclude that BI1 is essential in maintaining mitochondrial homeostasis and alleviating cardiac microvascular IR injury. Deregulated BI1 via the XO/ROS/F-actin pathways plays a causative role in the development of cardiac microvascular reperfusion injury.     

Propionate alleviates myocardial ischemia-reperfusion injury aggravated by Angiotensin II dependent on caveolin-1/ACE2 axis through GPR41

Myocardial ischemia/reperfusion (I/R) injury is still a lack of effective therapeutic drugs, and its molecular mechanism is urgently needed. Studies have shown that the intestinal flora plays an important regulatory role in cardiovascular injury, but the specific mechanism has not been fully elucidated. In this study, we found that an increase in Ang II in plasma was accompanied by an increase in the levels of myocardial injury during myocardial reperfusion in patients with cardiopulmonary bypass. Furthermore, Ang II treatment enhanced mice myocardial I/R injury, which was reversed by caveolin-1 (CAV-1)-shRNA or strengthened by angiotensin-converting enzyme 2 (ACE2)-shRNA. The results showed that CAV-1 and ACE2 have protein interactions and inhibit each other''s expression. In addition, propionate, a bacterial metabolite, inhibited the elevation of Ang II and myocardial injury, while GPR41-shRNA abolished the protective effects of propionate on myocardial I/R injury. Clinically, the propionate content in the patient''s preoperative stool was related to Ang II levels and myocardial I/R injury levels during myocardial reperfusion. Taken together, propionate alleviates myocardial I/R injury aggravated by Ang II dependent on CAV-1/ACE2 axis through GPR41, which provides a new direction that diet to regulate the intestinal flora for treatment of myocardial I/R injury.     

Pirfenidone alleviates cardiac fibrosis induced by pressure overload via inhibiting TGF‐β1/Smad3 signalling pathway

Cardiac fibrosis critically injured the cardiac structure and function of the hypertensive patients. However, the anti‐fibrotic strategy is still far from satisfaction. This study aims to determine the effect and mechanism of Pirfenidone (PFD), an anti‐lung fibrosis medicine, in the treatment of cardiac fibrosis and heart failure induced by pressure overload. Male C57BL/6 mice were subjected to thoracic aorta constriction (TAC) or sham surgery with the vehicle, PFD (300 mg/kg/day) or Captopril (CAP, 20 mg/kg/day). After 8 weeks of surgery, mice were tested by echocardiography, and then sacrificed followed by morphological and molecular biological analysis. Compared to the sham mice, TAC mice showed a remarkable cardiac hypertrophy, interstitial and perivascular fibrosis and resultant heart failure, which were reversed by PFD and CAP significantly. The enhanced cardiac expression of TGF‐β1 and phosphorylation of Smad3 in TAC mice were both restrained by PFD. Cardiac fibroblasts isolated from adult C57BL/6 mice were treated by Angiotensin II, which led to significant increases in cellular proliferation and levels of α‐SMA, vimentin, TGF‐β1 and phosphorylated TGF‐β receptor and Smad3. These changes were markedly inhibited by pre‐treatment of PFD. Collectively, PFD attenuates myocardial fibrosis and dysfunction induced by pressure overload via inhibiting the activation of TGF‐β1/Smad3 signalling pathway.