Haiyi Yu

Two-dimensional surface enhanced Raman mapping of differently prepared gold substrates with an azobenzene self-assembled monolayer

Abstract An azobenzene self-assembled monolayer (SAM) was used to obtain the two-dimensional surface-enhanced Raman scattering (SERS) maps of gold substrates, which were prepared by electrochemical roughening and colloidal Au nanoparticle assembling, respectively. The Raman maps thus obtained showed that the lateral distribution of SERS intensity varies to a significant extent over the substrate surface. Especially, the nanoparticle substrate has a more homogeneous distribution of SERS enhancement factors than that of the electrochemically roughened one, which are believed to reflect the different morphology of these two substrates.

Macrophage Migration Inhibitory Factor for the Early Prediction of Infarct Size

Background Early diagnosis and knowledge of infarct size is critical for the management of acute myocardial infarction (MI). We evaluated whether early elevated plasma level of macrophage migration inhibitory factor (MIF) is useful for these purposes in patients with ST‐elevation MI (STEMI). Methods and Results We first studied MIF level in plasma and the myocardium in mice and determined infarct size. MI for 15 or 60 minutes resulted in 2.5‐fold increase over control values in plasma MIF levels while MIF content in the ischemic myocardium reduced by 50% and plasma MIF levels correlated with myocardium‐at‐risk and infarct size at both time‐points (P<0.01). In patients with STEMI, we obtained admission plasma samples and measured MIF, conventional troponins (TnI, TnT), high sensitive TnI (hsTnI), creatine kinase (CK), CK‐MB, and myoglobin. Infarct size was assessed by cardiac magnetic resonance (CMR) imaging. Patients with chronic stable angina and healthy volunteers were studied as controls. Of 374 STEMI patients, 68% had elevated admission MIF levels above the highest value in healthy controls (>41.6 ng/mL), a proportion similar to hsTnI (75%) and TnI (50%), but greater than other biomarkers studied (20% to 31%, all P<0.05 versus MIF). Only admission MIF levels correlated with CMR‐derived infarct size, ventricular volumes and ejection fraction (n=42, r=0.46 to 0.77, all P<0.01) at 3 day and 3 months post‐MI. Conclusion Plasma MIF levels are elevated in a high proportion of STEMI patients at the first obtainable sample and these levels are predictive of final infarct size and the extent of cardiac remodeling.

MicroRNA-214 Mediates Isoproterenol-induced Proliferation and Collagen Synthesis in Cardiac Fibroblasts

The action of β-adrenergic receptors (β-ARs) induces cardiac fibroblast (CF) proliferation and collagen synthesis and is a major source of the cardiac fibrosis caused by various diseases. Recently, microRNA-214 (miR-214) was found to play an important role in the pathogenesis of cardiac remodelling. In the present study, we examined the role and the underlying mechanism of miR-214 in isoproterenol (ISO, a β-AR agonist)-induced CF proliferation and collagen synthesis. The expression of miR-214 was increased in both ISO-mediated fibrotic heart tissue and fibroblasts. Downregulation of miR-214 by antagonists attenuated the proliferation and collagen synthesis in ISO-treated CFs. Using bioinformatics analysis and luciferase assays, mitofusin2 (Mfn2), a critical regulator of cell proliferation and tissue fibrosis, was identified as a direct target gene of miR-214; this result was confirmed by western blot analysis. Additionally, corresponding to the upregulation of miR-214, the expression of Mfn2 was downregulated in the fibrotic heart and fibroblasts. Furthermore, the downregulation of miR-214 inhibited the activation of ERK1/2 MAPK signalling induced by ISO treatment. In conclusion, our study demonstrated that miR-214 mediates CF proliferation and collagen synthesis via inhibition of Mfn2 and activation of ERK1/2 MAPK signalling, which provides a new explanation for the mechanism of β-AR activation-induced cardiac fibrosis.

Up-Regulating Relaxin Expression by G-Quadruplex Interactive Ligand to Achieve Antifibrotic Action

Myocardial fibrosis is a key pathological change in a variety of heart diseases contributing to the development of heart failure, arrhythmias, and sudden death. Recent studies have shown that relaxin prevents and reverses cardiac fibrosis. Endogenous expression of relaxin was elevated in the setting of heart disease; the extent of such up-regulation, however, is insufficient to exert compensatory actions, and the mechanism regulating relaxin expression is poorly defined. In the rat relaxin-1 (RLN1, Chr1) gene promoter region we found presence of repeated guanine (G)-rich sequences, which allowed formation and stabilization of G-quadruplexes with the addition of a G-quadruplex interactive ligand berberine. The G-rich sequences and the G-quadruplexes were localized adjacent to the binding motif of signal transducer and activator of transcription (STAT)3, which negatively regulates relaxin expression. Thus, we hypothesized that the formation and stabilization of G-quadruplexes by berberine could influence relaxin expression. We found that berberine-induced formation of G-quadruplexes did increase relaxin gene expression measured at mRNA and protein levels. Formation of G-quadruplexes significantly reduced STAT3 binding to the promoter of relaxin gene. This was associated with consequent increase in the binding of RNA polymerase II and STAT5a to relaxin gene promoter. In cardiac fibroblasts and rats treated with angiotensin II, berberine was found to suppress fibroblast activation, collagen synthesis, and extent of cardiac fibrosis through up-regulating relaxin. The antifibrotic action of berberine in vitro and in vivo was similar to that by exogenous relaxin. Our findings document a novel therapeutic strategy for fibrosis through up-regulating expression of endogenous relaxin.

IL-18 cleavage triggers cardiac inflammation and fibrosis upon β-adrenergic insult

Aims Rapid over-activation of β-adrenergic receptor (β-AR) upon stress leads to cardiac inflammation, a prevailing factor that underlies heart injury. However, mechanisms by which acute β-AR stimulation induce cardiac inflammation still remain unknown. Here, we set out to identify the crucial role of inflammasome/interleukin (IL)-18 in initiating and maintaining cardiac inflammatory cascades upon β-AR insult. Methods and results Male C57BL/6 mice were injected with a single dose of β-AR agonist, isoproterenol (ISO, 5 mg/kg body weight) or saline subcutaneously. Cytokine array profiling demonstrated that chemokines dominated the initial cytokines upregulation specifically within the heart upon β-AR insult, which promoted early macrophage infiltration. Further investigation revealed that the rapid inflammasome-dependent activation of IL-18, but not IL-1β, was the critical up-stream regulator for elevated chemokine expression in the myocardium upon ISO induced β1-AR-ROS signalling. Indeed, a positive correlation was observed between the serum levels of norepinephrine and IL-18 in patients with chest pain. Genetic deletion of IL-18 or the up-stream inflammasome component NLRP3 significantly attenuated ISO-induced chemokine expression and macrophage infiltration. In addition, IL-18 neutralizing antibodies selectively abated ISO-induced chemokines, proinflammatory cytokines and adhesion molecules but not growth factors. Moreover, blocking IL-18 early after ISO treatment effectively attenuated cardiac inflammation and fibrosis. Conclusion Inflammasome-dependent activation of IL-18 within the myocardium upon acute β-AR over-activation triggers cytokine cascades, macrophage infiltration and pathological cardiac remodelling. Blocking IL-18 at the early stage of β-AR insult can successfully prevent inflammatory responses and cardiac injuries.

Heat Shock Protein 70 Acts as a Potential Biomarker for Early Diagnosis of Heart Failure

Early identification for heart failure (HF) may be useful for disease modifying treatment in order to reduce heart disease progression or even to reverse it. In our previous studies, we have revealed a group of heat shock proteins (HSPs) which might be related to neonatal rat cardiomyocyte hypertrophy by proteomic approach. Here, we confirm that HSPs, including HSP27 and HSP70, altered in the early stage of cardiac remodeling in vivo animal model. Furthermore, plasma concentrations of those HSPs and their potential screening value were evaluated at different stages in 222 patient subjects. Plasma HSP27, HSP70 and HSP90 were measured using enzyme-linked immunosorbent assay. Results indicate that HSP70 was positively correlated to the severity (progression) of HF (r = 0.456, p<0.001). The area under the rate of change (ROC) curve was 0.601 (p = 0.017) in patients with stage B HF and 0.835 (p<0.001) in those with stage C HF. However, HSP27 and HSP90 did not display significant changes in any stage of HF in this study. Taken together, plasma concentrations of HSP70 elevated with the progression of HF and might act as a potential screening biomarker for early diagnosis of HF.

miRNA-711-SP1-collagen-I pathway is involved in the anti-fibrotic effect of pioglitazone in myocardial infarction

Although microRNAs (miRNAs) have been intensively studied in cardiac fibrosis, their roles in drug-mediated anti-fibrotic therapy are still unknown. Previously, Pioglitazone attenuated cardiac fibrosis and increased miR-711 experimentally. We aimed to explore the role and mechanism of miR-711 in pioglitazone-treated myocardial infarction in rats. Our results showed that pioglitazone significantly reduced collagen-I levels and increased miR-711 expression in myocardial infarction heart. Pioglitazone increased the expression of miR-711 in cardiac fibroblasts, and overexpression of miR-711 suppressed collagen-I levels in angiotensin II (Ang II)-treated or untreated cells. Transfection with antagomir-711 correspondingly abolished the pioglitazone-induced reduction in collagen-I levels. Bioinformatics analysis identified SP1, which directly promotes collagen-I synthesis, as the putative target of miR-711. This was confirmed by luciferase assay and western blot analysis. Additionally, increased SP1 expression was attenuated by pioglitazone in myocardial infarction heart. Furthermore, transfection of antagomir-711 attenuated pioglitazone-reduced SP1 expression in cardiac fibroblasts with or without Ang II stimulation. We conclude that pioglitazone up-regulated miR-711 to reduce collagen-I levels in rats with myocardial infarction. The miR-711-SP1-collagen-I pathway may be involved in the anti-fibrotic effects of pioglitazone. Our findings may provide new strategies for miRNA-based anti-fibrotic drug research.

Serial changes of mean platelet volume in relation to Killip Class in patients with acute myocardial infarction and primary percutaneous coronary intervention.

INTRODUCTION Mean platelet volume (MPV) is related to the reactivity of platelets. Among survivors of acute myocardial infarction (MI), greater MPV is known to be associated with impaired reperfusion and higher mortality. The aims of the study is to investigate the dynamic changes of MPV and the relation between MPV and cardiac function in patients with acute MI and received primary percutaneous coronary intervention (PCI). MATERIALS AND METHODS This retrospective cohort study included patients presented during January 2008 to March 2011 to Peking University Third Hospital with ST-segment elevation MI. All patients received successful PCI. MPV was measured serially, using a Sysmex XE2100 haematology analyser, from admission to day-7 after MI. RESULTS In 375 patients, MPV was at its highest value (10.2±1.0 fL) and correlated well with platelet distribution width (PDW, r=0.833, p<0.0001) at the admission, and then reduced by 16% within the 24 hours, together with marked weakening of its correlation with PDW. Patients with poorer ventricular function, estimated by high Killip Class (≥2, n=96), had higher MPV values at all-time points. By logistic regression model and after adjusting for related confounders, high MPV remained as an independent predictor of Killip Class ≥2 (OR 1.873, CI 95% 1.373-2.673, p=0.001). Clopidogrel pre-usage resulted in significant MPV reduction on admission. CONCLUSIONS MPV undergoes rapid and dynamic changes during the acute phase of MI, and was higher in patients with high Killip Class, suggesting a predictive value of MPV in ventricular dysfunction and clinical outcome of acute phase of MI.

Association between Peak Neutrophil Count, Clopidogrel Loading Dose, and Left Ventricular Systolic Function in Patients with Primary Percutaneous Coronary Intervention

Inflammation plays an important role in plaque development and left ventricular remodeling during acute myocardial infarction (AMI). Clopidogrel may exhibit some anti-inflammatory properties and high loading dose of clopidogrel results in improved clinical outcomes in patients with AMI. 357 patients who received successful primary percutaneous coronary intervention from January 2008 to March 2011 in Peking University Third Hospital were included in this study. Different loading dose of clopidogrel (300 mg, 450 mg, or 600 mg) was given at the discretion of the clinician. Neutrophils reached their peak values on the first day after AMI. Higher levels of peak neutrophil and lower left ventricular ejection fraction (LVEF) were found in patients of low clopidogrel loading dose group (300 mg or 450 mg). After adjusting for the related confounders, a logistic regression model showed that low clopidogrel loading dose remained an independent predictor of low LVEF (LVEF ≤ 50%) [OR: 1.97, 95% CI: 1.03–3.79, P = 0.04]. Low clopidogrel loading dose was associated with higher peak neutrophil count and poor left ventricular systolic function, suggesting an important role of clopidogrel loading dose in the improvement of left ventricular function and high loading dose may exhibit better anti-inflammatory properties.

Irreversible Adsorption and Reduction of p-Nitrothio-Phenol Monolayers on Gold: Electrochemical in Situ Surface Enhanced Raman Spectroscopy

Abstract The redox behavior of p-nitrothiophenol (p-NTP) monolayers on gold was studied by electrochemical in situ surface enhanced Raman spectroscopy (SERS). The chemical adsorption of p-NTP on gold through Au-S bonding was confirmed by the comparison between the Raman spectra of parent molecules and that of the monolayer. The irreversible reduction of p-NTP monolayers to p-aminothiophenol (p-ATP) monolayers was evidenced by the observed potential dependent spectral changes. The present results demonstrated the potential of SERS in investigating the adsorbate-substrate interaction and in monitoring surface reactions at a monolayer scale.