[Irisin Alleviates Inflammatory Injury in Diabetic Cardiomyopathy by Regulating NF-κB Pathway].

Objective: To investigate the protective effect of irisin in diabetic cardiomyopathy (DCM) and its mechanism. Methods: A mouse model of DCM was established by high-fat diet combined with the injection of streptozotocin. The mice were assigned to a control group, a DCM group, a DCM+low-dose irisin group, a DCM+high-dose irisin group, and a DCM+pyrrolidine dithiocarbamate (PDTC) (nuclear factor [NF]-κB inhibitor) group. Then, the mice received irisin intervention for 3 weeks after successful modeling. Myocardial morphologic changes were observed by hematoxylin and eosin (HE) staining and Masson staining. The levels of serum creatine kinase (CK) and creatine kinase isoenzyme CK-MB were examined by automatic biochemical analyzer. H9c2 cells were divided into the control group, high glucose and high lipid (HG/HL) group, HG/HL+low-dose irisin group, HG/HL+high-dose irisin group, and HG/HL+PDTC group. CCK-8 assay was conducted to determine cell viability. The expression levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1ß, and IL-6 in the myocardial tissue and the cells were determined by ELISA. In addition, nuclear translocation of NF-κB p65 protein and the protein expression level of NF-κB inhibitor protein α (IκBα) in the myocardial tissue and the cells were determined by Western blot. Results: According to the results of animal experiment, low and high doses of irisin could alleviate the pathological injury and fibrosis of myocardial tissue to varying degrees. Irisin inhibited the levels of CK, CK-MB, and inflammatory factors, up-regulated IκB protein expression, and diminished NF-κB nuclear translocation. According to the results of cell experiment, low and high doses of irisin could enhance H9c2 cell viability to varying degrees, increase the level of intracellular IκB proteins, and inhibit NF-κB p65 nuclear translocation and inflammatory factor expression. The changes in these aspects in the DCM+low-dose irisin group and the DCM+high-dose irisin group were similar to those in the DCM+PDTC group. Conclusion: Through inhibiting NF-κB p65 nuclear translocation, irisin may reduce the inflammatory response in the myocardial tissue of DCM mice and H9c2 cells of myocardial injury induced by high glucose and high fat, thereby exerting a protective effect on myocardium.

Curcumin affects ox-LDL-induced IL-6, TNF-α, MCP-1 secretion and cholesterol efflux in THP-1 cells by suppressing the TLR4/NF-κB/miR33a signaling pathway.

The aim of the present study was to study the molecular mechanism of how curcumin decreases the formation of ox-LDL induced human monocyte macrophage foam cells, promotes the efflux of cholesterol and reduces the secretion of inflammatory cytokines. In vitro cultured THP-1 cells were induced to become macrophages using phorbol-12-myristate-13-acetate. The cells were then pre-treated with curcumin before inducing the foam cell model by addition of oxidized low-density lipoprotein (ox-LDL). Western blot assays were used to detect expression levels of toll-like receptor (TLR)4, nuclear factor κB (NF-κB), NF-κB inhibitor α (IκBα), phosphorylated-IκBα and ATP binding cassette transporter (ABC)A1. Reverse transcription-quantitative PCR was employed to examine mRNA levels of TLR4, microRNA (miR)33a and ABCA1. ELISAs were used to detect inflammatory factors, including tumor necrosis factor (TNF)-α, monocyte chemotactic protein (MCP)-1 and interleukin (IL)-6. ox-LDL successfully induced the foam cell model, promoted phosphorylation of IκBα, promoted nuclear translocation of NF-κB, promoted the expression of TLR4 and miR33a, and promoted the secretion of TNF-α, MCP-1 and Il-6. Additionally, ox-LDL reduced the expression of ABCA1 and cholesterol efflux. However, pretreatment with curcumin increased the expression of ABCA1 and cholesterol efflux and suppressed secretion of TNF-α, MCP-1 and Il-6. TLR4 antibodies, the NF-κB blocker, PDTC, and the miR33a inhibitor also reduced the abnormal transformations induced by ox-LDL. Curcumin promoted cholesterol efflux by suppressing the TLR4/NF-κB/miR33a signaling pathway, and reduced the formation of foam cells and the secretion of inflammatory factors.

Hyperpolarization-Activated Cyclic Nucleotide-Gated Ion (HCN) Channels Regulate PC12 Cell Differentiation Toward Sympathetic Neuron.

Hyperpolarization-activated cyclic nucleotide-gated ion channels (HCN channels) are widely expressed in the central and peripheral nervous systems and organs, while their functions are not well elucidated especially in the sympathetic nerve. The present study aimed to investigate the roles of HCN channel isoforms in the differentiation of sympathetic neurons using PC12 cell as a model. PC12 cells derived from rat pheochromocytoma were cultured and induced by nerve growth factor (NGF) (25 ng/ml) to differentiate to sympathetic neuron-like cells. Sympathetic directional differentiation of PC12 cells were evaluated by expressions of growth-associated protein 43 (GAP-43) (a growth cone marker), tyrosine hydroxylase (TH) (a sympathetic neuron marker) and neurite outgrowth. Results show that the HCN channel isoforms (HCN1-4) were all expressed in PC12 cells; blocking HCN channels with ivabradine suppressed NGF-induced GAP-43 expression and neurite outgrowth; silencing the expression of HCN2 and HCN4 using silenced using small interfering RNAs (siRNA), rather than HCN1 and HCN3, restrained GAP-43 expression and neurite outgrowth, while overexpression of HCN2 and HCN4 channels with gene transfer promoted GAP-43 expression and neurite outgrowth. Patch clamp experiments show that PC12 cells exhibited resting potentials (RP) of about -65 to -70 mV, and also presented inward HCN channel currents and outward (K+) currents, but no inward voltage-gated Na+ current was induced; NGF did not significantly affect the RP but promoted the establishment of excitability as indicated by the increased ability to depolarize and repolarize in the evoked suspicious action potentials (AP). We conclude that HCN2 and HCN4 channel isoforms, but not HCN1 and HCN3, promote the differentiation of PC12 cells toward sympathetic neurons. NGF potentiates the establishment of excitability during PC12 cell differentiation.

[Urine cardiac specific microRNA-1 level in patients with ST segment elevation acute myocardial infarction].

OBJECTIVE: To observe the change of urine level of cardiac specific microRNA-1 (miR-1) in patients with ST segment elevation acute myocardial infarction (STEAMI) and investigate its potential applications. METHODS: Urine samples were collected from 20 STEAMI patients within 12 hours after STEAMI and from 20 healthy volunteers as control. Urine miR-1 concentrations were measured with real-time quantity reverse transcription-polymerase chain reaction (qRT-PCR), at the same time serum cardiac troponin I (cTnI) and MB isoenzyme of creatine kinase (CK-MB) concentrations were measured. RESULTS: Serum level of cTnI, CK-MB and urine level of miR-1 in STEAMI patients were obviously higher than those in healthy control group [cTnI in blood: 19.27±7.53 µg/L vs. 0.02±0.01 µg/L, CK-MB in blood: 93.82±12.30 µg/L vs. 0.86±0.63 µg/L, miR-1 in urine (Ct value): 45.50±4.21 vs. 52.63±4.41, P<0.05 or P<0.01]. The urine miR-1 level in patients with STEAMI had a strong correlation with serum CK-MB or cTnI when CK-MB < 300 µg/L and cTnI <50 µg/L (Ct value of urine miR-1 with blood CK-MB: r=-0.81, P<0.01; Ct value of urine miR-1 with blood cTnI: r=-0.63, P<0.05). CONCLUSIONS: The results suggest that urine miR-1 could be a novel sensitive biomarker the early diagnosis of SETAMI.

[Changes in cardiac specific microRNA-208a level in peripheral blood in ST segment elevation acute myocardial infarction patients].

OBJECTIVE: To observe serum cardiac specific microRNA-208a (miR-208a) levels in ST segment elevation acute myocardial infarction (STEAMI) patients, and to explore the role of serum miR-208a levels in the diagnosis of STEAMI. METHODS: The serum miR-208a concentrations were assessed within 12 hours after STEAMI, while 30 healthy individuals as control. Serum miR-208a concentrations were measured with real-time quantity reverse transcription-polymerase chain reaction (qRT-PCR), and serum cardiac troponin I (cTnI) or MB isoenzyme of creatine kinase (CK-MB) concentrations were measured with enzyme linked immunosorbent assay (ELISA). RESULTS: The contents of serum cTnI or CK-MB in STEAMI patients were significantly higher than those in healthy individuals (cTnI: 17.72±8.43 µg/L vs. 0.05±0.01 µg/L, CK-MB: 250.83±177.26 µg/L vs. 71.20±20.50 µg/L, both P<0.01). Serum miR-208a concentrations were detected in all individuals with STEAMI within 60 PCR cycle (0-6 hours: 44.95±4.77, 6-12 hours: 43.98±4.68), but were beyond detection for all individuals in the healthy control group. The serum miR-208a relative levels in STEAMI patients were at least more than 215 fold than that in healthy persons, compared with qRT-PCR (Ct=60) of miR-208a in healthy control persons (P<0.01). CONCLUSION: Serum miR-208a may be a new biomarker the early diagnosis of STEAMI patients.

Effects of autologous stem cell transplantation on ventricular electrophysiology in doxorubicin-induced heart failure.

To investigate whether stem cell transplantation affects ventricular electrophysiology in vivo, either autologous bone marrow mesenchymal stem cells or skeletal myoblast cells were transplanted via a catheter into a doxorubicin-treated failing heart. Four weeks after transplantation, electrophysiological investigation showed that transplantation of either cell type prolonged the local activation time and increased the activation time dispersion. In the stem cell transplantation groups, a positive correlation was demonstrated between activation time dispersion and the number of stem cell-derived cells in the pacing site. It is concluded that transplantation of either mesenchymal stem cells or skeletal myoblast cells might exacerbate abnormalities of local ventricular conduction in the doxorubicin-treated failing heart.