microRNA-665 silencing improves cardiac function in rats with heart failure through activation of the cAMP signaling pathway.

Heart failure (HF) is a disease with high mortality and morbidity rate. Previous studies have shown that microRNAs (miRNAs) may be implicated in the pathogenesis of HF, potentially being able to improve the cardiac function in an HF rat model. The present study was designed to define the role of miR-665 in the cardiac function of the HF rats. Following the establishm;ent of the rat models of HF, the functional role miR-665 in HF was determined using an ectopic expression and knockdown experiments. The cardiac function was evaluated with the determination of ventricular mass index and hemodynamic parameters. Terminal deoxynucleotidyl transferase dUTP nick end labeling staining was performed, with the apoptosis of cardiac cells detected in the process. The expression of miR-665, glucagon-like peptide 1 receptor (GLP1R), cyclic adenosine monophosphate (cAMP) signaling pathway-related, and apoptosis-related genes was examined. Enzyme-linked immunosorbent assay was conducted to determine the levels of inflammation-related genes. Initially, the upregulation of miR-665, downregulation of GLP1R, and inactivation of cAMP signaling pathway were observed in HF rats. GLP1R was a target of miR-665. Forced expression of miR-665 promoted cell apoptosis and inhibited GLP1R and the cAMP signaling pathway. In addition, miR-665 overexpression has been known to impair cardiac function, promote inflammatory response while elevating malondialdehyde and superoxide dismutase levels, and decreasing mitochondrial respiratory chain enzyme activities. Furthermore, we also observed that the effects of miR-665 inhibition had been reversed when the cAMP signaling pathway was also inhibited. This study demonstrates that miR-665 inhibition can stabilize the cardiac function of HF rats via the cAMP signaling pathway via upregulation of the GLP1R.

DUSP14 knockout accelerates cardiac ischemia reperfusion (IR) injury through activating NF-κB and MAPKs signaling pathways modulated by ROS generation.

Inflammation and oxidative stress are significantly involved in the progression of a variety of diseases, including myocardial ischemia/reperfusion (IR). In the present study, we hypothesized a protective role of dual-specificity phosphatase 14 (DUSP14) in myocardial IR, as well as the underlying molecular mechanism. The results indicated that DUSP14 was down-regulated following cardiac IR injury. Subsequently, the wild type (WT) and DUSP14-knockout (KO) mice were included to further reveal the potential role of DUSP14 in cardiac IR injury progression. DUSP14-KO mice exhibited increased infarction area and elevated apoptosis, as evidenced by the increased TUNEL-positive cells in ischemia heart following reperfusion compared to WT mice. Further, DUSP14-KO significantly aggregated cardiac dysfunction of mice after IR injury. Cardiac IR injury to DUSP14-KO mice led to markedly increased expression of pro-inflammatory cytokines and activated nuclear factor-κB (NF-κB) pathway in the heart in comparison to WT mice. Meanwhile, mitogen-activated protein kinases (MAPKs), including p38, ERK1/2 and JNK, were significantly activated by DUSO14-KO in mice after IR injury. Compared to WT mice, DUSP14-KO mice showed markedly increased oxidative stress markers in cardiac tissues, including malondialdehyde (MDA), NADPH oxidase-4 (NOX4) and p47, while decreased activities or expressions of anti-oxidants, such as glutathione (GSH), glutathione peroxidase (GPx), glutathion reductases (GR), superoxide dismutase (SOD) and hemeoxygenase-1 (HO-1). DUSP14-knockdown (KD) in primary cardiomyocytes using its specific siRNA sequence elevated hypoxia and reoxygenation (HR)-induced activation of NF-κB and MAPKs signaling pathways, and reactive oxygen species (ROS) generation. Intriguingly, pre-treatment of ROS scavenger, N-acetylcysteine (NAC), markedly abolished DUSP14-KD-augmented NF-κB and MAPKs activation in HR-stimulated primary cardiomyocytes. Together, the results above indicated that DUSP14 might be served as a positive regulator to attenuate cardiac IR injury. Suppressing DUSP14 exacerbated cardiac injury through activating NF-κB and MAPKs signaling pathways regulated by ROS production. Thus, DUSP14 could be a valuable target for developing treatments for myocardial IR injury.

[Analysis of death characteristics and its potential mechanisms in rats with endotoxin- induced cardiomyopathy].

OBJECTIVE: To approach the changes in heart failure and dying regularity of rats with endotoxin-induced cardiomyopathy, and to offer some help for clinical diagnosing and further investigation. METHODS: Injecting refined endotoxin (10 mg/kg) via vein of Wistar rats. The first experiment: antidromic observing the endotoxic rats from death to the beginning to discover the performance of clinic heart function which could forecast death. The second experiment: setting 6 rats per group, respectively killing the rats at 4, 8, 16, 24, 32, 40, 48 and 72 hours after endotoxin injection, and killing 6 normal rats as control group, getting the tissue of left ventricle for biochemistry test, routine pathological examination, transmission electron microscope examination, expression level of α(1)-actin gene with reverse transcription-polymerase chain reaction (RT-PCR), and serum creatine kinase (CK) was test within 24 hours. RESULTS: The first experiment: heart rate (HR) and left ventricular end-systolic pressure (LVESP) of endotoxic rats began significant lower than normal at 4 hours before death (F(1)=22.032, P(1)=0.000; F(2)=29.420, P(2)=0.000), maximum rate of rise/drop of left ventricular pressure (±dp/dt max) began significant lower than normal at 8 hours before death (F(1)=17.272, P(1)=0.000; F(2)=19.685, P(2)=0.000), left ventricular end-diastolic pressure (LVEDP) showed no significant during the whole time (F=0.265, P=0.988). The heart function of all the rats showed no significant changes in the first 4 hours after injection. Mortality was 73.9% from injection to 24 hours later. Most of them died in 8-16 hours after injection. The one who had survived over 24 hours could have 2/3 probability to survive to 48 hours. The second experiment: CK in serum of different groups showed no significant difference (F=0.402, P=0.805), but showed obvious discreteness in each group except normal group. Electron microscopy and pathological examination showed obvious intracellular and intercellular damage since 8 hours later from injection. Pathology displayed that cells range disorder, mitochondria swelling, capillary hemorrhage, transverse striation disappearing, construction of myocardial cell loosing, and lateral dissociation phenomena. Electron microscopy discovered that the fiber direction and transverse striation became vague and disappeared, mitochondria got injury, the fiber became disordered, cell-cell junction were damaged seriously. Compared with the control group (0.637±0.160), the gene expression level of α(1)-actin decreased after endotoxin injection. The value dropped to the bottom at 8 hours (0.493±0.067) after injection and then rised slowly but dropped to the second wave trough again at 32 hours (0.875±0.128), but had no statistic significance; the expression of α(1)-actin gene eventually rised significantly at 40, 48, 72 hours after injection (2.231±0.545, 1.850±0.436, 2.062±0.340, all P<0.01). CONCLUSIONS: Endotoxic myocardiopathy does not result from plasmalemma destroy. Damage of α(1)-actin is a significantly important factor for endotoxic myocardiopathy.

[Changes of thyroxin and monocyte human leukocyte antigen-DR expression in senior patients with sepsis].

OBJECTIVE: To investigate the changes of thyroxin and monocyte human leukocyte antigen-DR expression in senior patients with sepsis and explore their clinical significance. METHODS: According to the 2001 SCCM/ESICM/ACCP/ATS/SIS international sepsis definitions, 125 senior patients with sepsis free of thyroid conditions were divided into non-severe sepsis group (n=86) and severe sepsis group (n=39), with another 30 healthy subjects as the control. Thyroid function was assayed by chemoluminescence method in these patients and monocyte HLA-DR expression was determined by flow cytometry. RESULTS: Compared with the control group and non-severe sepsis cases, the levels of free T3 (FT3), free T4 (FT4), T3, T4 and monocyte HLA-DR expression were significantly lower in severe sepsis cases (P<0.05), but the levels of thyroid stimulating hormone (TSH) were comparable between the 3 groups (P>0.05). The non-severe sepsis cases showed significantly lower levels of FT3, FT4, T3, T4, TSH and monocyte HLA-DR expression than the control group (P<0.05). In severe sepsis group, the levels of FT3, FT4, T3, T4 and monocyte HLA-DR expression showed significant differences between the fatal cases and surviving cases (P<0.05). CONCLUSION: The levels of thyroxin and monocyte human leukocyte antigen-DR expression are obviously lower in senior patients with severe sepsis, and their detection may well indicate the severity of the condition and help make prognostic judgment.

[Changes in the mRNA expressions of myocardial cytoskeletal proteins in endotoxemic rats].

OBJECTIVE: To investigate the changes of the mRNA expressions of myocardial cytoskeletal proteins in endotoxemic rats. METHODS: Thirty-seven Wistar rats were randomized into two groups with injection of 10 mg/kg lipopolysaccharide (LPS) or normal saline through the femoral vein. The cardiac function of the rats was monitored continuously for 24 h, and the morphological changes of the cardiac myocytes were observed with HE staining and electron microscope. The mRNA levels of myocardial cytoskeletal proteins including actin, tubulin and desmin were determined by RT-PCR. RESULTS: No significant difference was found in the number of CD3(+)T lymphocytes in the TILs between different groups. After the immunotherapy, the peLPS injection resulted in significant impairment of the cardiac function and myocardial microstructure of the rats with reduced heart rate and left ventricular systolic pressure (LVSP). The mRNA expression of actin in the cardiac myocytes measured by fluorescence optical density was reduced significantly 8 h after LPS injection, and that of tubulin was decreased significantly 24 h after LPS treatment; desmin mRNA expression showed no significant variation after LPS injection. CONCLUSION: LPS can significantly impair the cardiac function of the rats possibly by inducing damages of the myocardial cytoarchitecture and causing changes in the mRNA expressions of such cytoskeletal proteins as actin and tubulin.

[Therapeutic effect of low-dose thyroxin in elderly patients with refractory heart failure and euthyroid sick syndrome].

OBJECTIVE: To investigate the therapeutic effect of low-dose thyroxin in elderly patients with refractory heart failure (RHF) and euthyroid sick syndrome (ESS). METHODS: Fifty-four elderly patients with RHF and ESS were randomized into conventional treatment group (n=32) and L-thyroxine group with additional oral L-thyroxine at the daily dose of 6.25-25 microg (n=22). The changes in the plasma levels of brain natriuretic peptides (BNP), left ventricular ejection fraction (LVEF), and cardiac function (NYHA level) of the two groups were compared after 1 month of treatment. RESULTS: Five patients receiving conventional treatment died due to severe arrhythmia during the treatment, and in the other 27 patients, the levels of plasma BNP, LVEF, and cardiac function showed no significant improvements after 1 month of treatment (P>0.01). In L-thyroxine group, no death or severe arrhythmia occurred, and the levels of plasma BNP, LVEF, and cardiac function were significantly improved after the treatment (P<0.01). No thyrotoxicosis occurred during the administration of L-thyroxine in the latter group. CONCLUSION: Low-dose L-thyroxine in addition to the conventional treatments may enhance the therapeutic effect in elderly patients with RHF and ESS.