MiR-808 inhibits cardiomyocyte apoptosis and expressions of caspase-3 and caspase-9 in rats with myocardial infarction by regulating TGF-β1 signaling pathway

OBJECTIVE

To investigate the effects of micro ribonucleic acid (miR)-808 on cardiomyocyte apoptosis and expressions of caspase-3 and caspase-9 in rats with myocardial infarction (MI) by regulating the transforming growth factor-β1 (TGF-β1) signaling pathway.

MATERIALS AND METHODS

A total of 24 specific pathogen-free female Sprague-Dawley rats were enrolled and randomly divided into normal group, model group, and miR-808 group, 8 rats in each group. In the model group and miR-808 group, MI model was prepared by ligation of the left anterior descending coronary artery in the rats. The miR-808 group was transfected with miR-808 lentivirus after the model was established. After one week of intervention, the expression of TGF-β1 was detected by reverse transcription-polymerase chain reaction (RT-PCR). The cardiac function of rats was determined by echocardiography. The myocardium of rats was observed by Masson staining. The cardiomyocyte apoptosis of rats was examined by TdT-mediated dUTP-biotin nick end labeling (TUNEL) method. The expression levels of caspase-3 and caspase-9 were detected by Western blotting.

RESULTS

The expression of TGF-β1 mRNA was higher in the model group than that in the normal group (p<0.05), but compared with that in the model group, it was lower in the miR-808 group. The myocardial function and cardiomyocyte survival rate in the miR-808 group was better and higher than those in the model group (p<0.05). The expression levels of caspase-3 and caspase-9 in the miR-808 group were lower than those in the model group (p<0.05).

CONCLUSIONS

MiR-808 can inhibit cardiomyocyte apoptosis in rats with MI by down-regulating TGF-β1 expression and inhibiting the expressions of caspase-3 and caspase-9.

IL-6 knockout ameliorates myocardial remodeling after myocardial infarction by regulating activation of M2 macrophages and fibroblast cells

OBJECTIVE

To investigate the effects of interleukin-6 (IL-6) gene knockout on myocardial remodeling after myocardial infarction (MI) in mice and the potential mechanism, to provide certain references for the prevention and treatment of MI in clinic.

MATERIALS AND METHODS

A total of 40 male C57 mice were divided into two groups, namely Sham group (n=20) and MI group (n=20), using a random number table. Another 20 mice with IL-6 gene knockout were enrolled into the MI + IL-6 KO group. The MI model was established by means of ligating the left anterior descending coronary artery of the mice. 28 d later, the survival status of the three groups of mice was recorded. In addition, the cardiac functions of each group of mice, including two-dimensional echocardiography, ejection fraction (EF%) and fractional shortening (FS%), were measured. The cross-sectional area and pathological change of the myocardial cells in cardiac tissues of each group of mice were detected via hematoxylin and eosin (H&E) staining. Immunohistochemistry was applied to determine the expression of tumor necrosis factor-alpha (TNF-α) in each group of mouse cardiac tissues. Moreover, immunofluorescent staining was utilized to measure the content of M2 macrophages in each group of mouse cardiac tissues.

RESULTS

The 28-d survival rate of the mice with IL-6 gene knockout was remarkably higher than that of the wild-type mice (p<0.05). Furthermore, the cardiac functions of the mice in the MI + IL-6 KO group were superior to those in the MI group, with markedly improved FS% and EF% (p<0.05). According to the H&E staining results, the cross-sectional areas of the heart and myocardial cells were decreased notably in MI + IL-6 KO group compared with those in the MI group (p<0.05). The immunohistochemical staining results showed that IL-6 knockout could lower the MI-induced high expression of TNF-α (p<0.05), and Masson's trichrome staining indicated that IL-6 knockout could also repress the degree of cardiac fibrosis. Moreover, it was discovered through immunofluorescent staining that the mice in the MI + IL-6 KO group had markedly elevated content of M2 macrophages in cardiac tissues than those in the MI group (p<0.05).

CONCLUSIONS

Inhibiting IL-6 gene expression can prominently ameliorate the MI-induced myocardial remodeling, whose mechanism is possibly associated with the activation of M2 macrophages and reduced collagen production in fibroblast cells.

Downregulated miRNA-26a-5p induces the apoptosis of endothelial cells in coronary heart disease by inhibiting PI3K/AKT pathway

OBJECTIVE

Multiple microRNAs (miRNAs) are abnormally expressed in endothelial cells during the occurrence of coronary artery disease (CAD). Previous researches have demonstrated that miRNA-26a-5p participates in regulating the proliferation of vascular smooth muscle cells and angiogenesis. The aim of this study was to clarify the role of miRNA-26a-5p in regulating cellular performances of endothelial cells in the progression of CAD.

PATIENTS AND METHODS

In vivo CAD model was successfully established by feeding high-fat diet in 8-week-old female ApoE/LDLR-/- mice. CAD mice were administered with miRNA-26a-5p NC or miRNA-26a-5p inhibitor, respectively. Meanwhile, coronary endothelial cells were isolated from CAD mice and normal controls. Relative levels of miRNA-26a-5p, the gene of phosphate and tension homology deleted on chromosome ten (PTEN) and vascular endothelial growth factor (VEGF) in CAD patients and coronary endothelial cells isolated from CAD mice were examined. The regulatory effect of miRNA-26a-5p on atherosclerosis-related genes in primary endothelial cells and HUVECs were detected as well. Moreover, the viability and apoptosis of primary endothelial cells with miRNA-26a-5p knockdown were assessed by cell counting kit-8 (CCK-8) assay and flow cytometry, respectively. Dual-luciferase reporter gene assay was conducted to identify the relationship between miRNA-26a-5p and PTEN. Furthermore, the regulatory role of miRNA-26a-5p in phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway was examined in endothelial cells.

RESULTS

MiRNA-26a-5p and VEGF were significantly downregulated in CAD patients and primary endothelial cells isolated from CAD mice. However, PTEN was significantly upregulated. CAD mice administrated with miRNA-26a-5p inhibitor exhibited remarkably upregulated ET-1, TxA2, and ANG II, as well as downregulated eNOS and PGI2. Conversely, transfection of miRNA-26a-5p mimics in HUVECs obtained the opposite trends. PTEN was identified as the direct target gene of miRNA-26a-5p. Moreover, significantly reduced viability and enhanced apoptotic rate were observed in endothelial cells isolated from CAD mice administrated with miRNA-26a-5p inhibitor. In addition, the protein level of p-AKT in endothelial cells with miRNA-26a-5p knockdown was significantly down-regulated.

CONCLUSIONS

MiRNA-26a-5p influences the proliferative and apoptotic abilities of endothelial cells isolated from CAD mice by targeting PTEN to activate PI3K/AKT pathway.

CIRBP protects H9C2 cells against myocardial ischemia through inhibition of NF-κB pathway

Myocardial ischemia is a major cause of death and remains a disease with extremely deficient clinical therapies and a major problem worldwide. Cold inducible RNA-binding protein (CIRBP) is reported to be involved in multiple pathological processes, including myocardial ischemia. However, the molecular mechanisms of myocardial ischemia remain elusive. Here, we first overexpressed CIRBP by transfection of pc-CIRBP (pcDNA3.1 containing coding sequenced for CIRBP) and silenced CIRBP by transfection of small interfering RNA targeting CIRBP (siCIRBP). pcDNA3.1 and the negative control of siCIRBP (siNC) were transfected into H9C2 cells to act as controls. We then constructed a cell model of myocardial ischemia through culturing cells in serum-free medium with hypoxia in H9C2 cells. Subsequently, AlamarBlue assay, flow cytometry and western blot analysis were used, respectively, to assess cell viability, reactive oxygen species (ROS) level and apoptosis, and expression levels of IκBα, p65 and Bcl-3. We demonstrated that CIRBP overexpression promoted cell proliferation (P<0.001), inhibited cell apoptosis (P<0.05), reduced ROS level (P<0.001), down-regulated phosphorylated levels of IκBα and p65 (P<0.01 or P<0.001), and up-regulated expression of Bcl-3 (P<0.001) in H9C2 cells with myocardial ischemia. The influence of CIRBP knockdown yielded opposite results. Our study revealed that CIRBP could protect H9C2 cells against myocardial ischemia through inhibition of NF-κB pathway.

Controlling multiple filaments by relativistic optical vortex beams in plasmas

Filamentation dynamics of relativistic optical vortex beams (OVBs) propagating in underdense plasma is investigated. It is shown that OVBs with finite orbital angular momentum (OAM) exhibit much more robust propagation behavior than the standard Gaussian beam. In fact, the growth rate of the azimuthal modulational instability decreases rapidly with increase of the OVB topological charge. Thus, relativistic OVBs can maintain their profiles for significantly longer distances in an underdense plasma before filamentation occurs. It is also found that an OVB would then break up into regular filament patterns due to conservation of the OAM, in contrast to a Gaussian laser beam, which in general experiences random filamentation.

Analysis of pancreas-infiltrating T cells in diabetic NOD mice: fusion with BW5147 yields a high frequency of islet-reactive hybridomas

Diabetes in NOD mice is an autoimmune disease which is characterized by the infiltration of islets of Langerhans by large numbers of T cells. Some of these infiltrating T cells are clearly islet-cells-specific; however, many or most of these T cells could be attracted nonspecificity into these lesions. To study NOD pancreas-infiltrating T cells, we fused these cells with BW5147 to make T cell hybridomas. Ninety-four pancreas-derived T hybrids were analyzed of which 12 responded specifically to islet cells by secreting IL-2. Only CD3+, CD4+ hybrids responded to islet cells in our assay, and a large proportion of these hybrids were islet-cell reactive. T cell receptor (TCR) V beta element usage was heterogeneous in islet-reactive hybridomas.