Effect of C reactive protein on the sodium-calcium exchanger 1 in cardiomyocytes.

Numerous previous studies have found that C-reactive protein (CRP) is associated with cardiac arrhythmia and cardiac remodeling. However, the underlying mechanisms of this association remain unclear. Sodium-calcium exchanger 1 (NCX1) serves an important role in the regulation of intracellular calcium concentration, which is closely related with cardiac arrhythmia and cardiac remodeling. The present study aimed to evaluate the effects of CRP on NCX1 and intracellular calcium concentration in cardiomyocytes. Primary neonatal mouse ventricular cardiomyocytes were cultured and treated with varying concentrations of CRP (0, 5, 10, 20 and 40 µg/ml). The cardiomyocytes were also treated with NF-κB-specific inhibitor PTDC and a specific inhibitor of the reverse NCX1 KB-R7943 before their intracellular calcium concentrations were measured. mRNA and protein expression levels of NCX1 were detected by reverse transcription-quantitative PCR and western blotting, respectively and intracellular calcium concentration was evaluated by flow cytometry. CRP treatment significantly increased mRNA and protein expression levels of NCX1 in myocytes (P=0.024), as well as intracellular calcium concentration (P=0.01). These results were significantly attenuated by the NF-κB-specific inhibitor PDTC and a specific inhibitor of the reverse NCX1, KB-R7943. CRP significantly upregulated NCX1 expression and increased intracellular calcium concentration in cardiomyocytes via the NF-κB pathway, suggesting that CRP may serve a pro-arrhythmia role via direct influence on the calcium homeostasis of cardiomyocytes.

Interleukin-33 alleviates diabetic cardiomyopathy through regulation of endoplasmic reticulum stress and autophagy via insulin-like growth factor-binding protein 3.

Prolonged endoplasmic reticulum (ER) stress is the key driving force behind diabetic cardiomyopathy (DCM). Autophagy is extensively implicated in adaptive mechanisms for cell survival. Interleukin-33 (IL-33) is known to be a potent cardiac protector, but its roles in DCM, ER stress, and autophagy are currently unknown. We aimed to explore the effects of IL-33 on DCM and characterize the roles that ER stress and autophagy play in DCM. The effects of IL-33 on DCM, ER stress, and autophagy were characterized both in db/db mice and in palmitic acid (PA)-treated cardiomyocytes. The manipulators of ER stress and autophagy were used to clarify their roles in DCM remittance conferred by IL-33. Gene expression analysis was used to identify IL-33-dependent regulators of ER stress and autophagy. Both db/db mice and PA-treated cells presented with enhanced levels of ER stress, apoptosis, and lipid deposition, as well as impaired autophagy, all of which could be reversed by IL-33. Treatment with IL-33 improved the cardiac diastolic function of diabetic mice. Nonselective autophagy inhibitors, such as 3-methyladenine (3-MA) or wortmannin, abolished the protective effects of IL-33, resulting in an increase in both ER stress and apoptosis. Strikingly, insulin-like growth factor-binding protein 3 (IGFBP3) was identified as the gene most significantly differentially expressed between IL-33 and control groups. Knockdown of IGFBP3 expression, similar to the effect of nonselective autophagy inhibitors, resulted in high levels of ER stress, impaired autophagy, and apoptosis that were not rescued upon treatment with IL-33. IL-33 abates DCM by alleviating ER stress and promoting autophagy. IGFBP3 is essential for IL-33-induced ER stress resolution and autophagic enhancement during DCM.

A Low-Normal Free Triiodothyronine Level Is Associated with Adverse Prognosis in Euthyroid Patients with Heart Failure Receiving Cardiac Resynchronization Therapy.

Thyroid dysfunction is prevalent in patients with heart failure (HF) and hypothyroidism is related to the adverse prognosis of HF subjects receiving cardiac resynchronization therapy (CRT). We aim to investigate whether low-normal free triiodothyronine (fT3) level is related to CRT response and the prognosis of euthyroid patients with HF after CRT implantation.One hundred and thirteen euthyroid patients who received CRT therapy without previous thyroid disease and any treatment affecting thyroid hormones were enrolled. All of patients were evaluated for cardiac function and thyroid hormones (serum levels of fT3, free thyroxine [fT4] and thyroid-stimulating hormone [TSH]). The end points were overall mortality and hospitalization for HF worsening. During a follow-up period of 39 ± 3 weeks, 36 patients (31.9%) died and 45 patients (39.8%) had hospitalization for HF exacerbation. A higher rate of NYHA III/IV class and a lower fT3 level were both observed in death group and HF event group. Multivariate Cox regression analyses disclosed that a lower-normal fT3 level (HR = 0.648, P = 0.009) and CRT response (HR = 0.441, P = 0.001) were both independent predictors of overall mortality. In addition, they were also both related to HF re-hospitalization event (P < 0.01 for both). Patients with fT3 < 3.00 pmol/L had a significantly higher overall mortality than those with fT3 ≥ 3.00 pmol/L (P = 0.027). Meanwhile, a higher HF hospitalization event rate was also found in patients with fT3 < 3.00 pmol/L (P < 0.001).A lower-normal fT3 level is correlated with a worse cardiac function an adverse prognosis in euthyroid patients with HF after CRT implantation.

Clinical effectiveness of telemedicine for chronic heart failure: a systematic review and meta-analysis.

Telemedicine interventions may be associated with reductions in hospital admission rate and mortality in patients with heart failure (HF). The present study is an updated analysis (as of June 30, 2016) of randomized controlled trials, where patients with HF underwent telemedicine care or the usual standard care. Data were extracted from 39 eligible studies for all-cause and HF-related hospital admission rate, length of stay, and mortality. The overall all-cause mortality (pooled OR=0.80, 95% CI 0.71 to 0.91, p<0.001), HF-related admission rate (pooled OR=0.63, 95% CI 0.53 to 0.76, p<0.001), and HF-related length of stay (pooled standardized difference in means=-0.37, 95% CI -0.72 to -0.02, p=0.041) were significantly lower in the telemedicine group (teletransmission and telephone-supported care), as compared with the control group. In subgroup analysis, all-cause mortality (pooled OR=0.69, 95% CI 0.56 to 0.86, p=0.001), HF-related admission rate (OR=0.61, 95% CI 0.42 to 0.88, p=0.008), HF-related length of stay (pooled standardized difference in means=-0.96, 95% CI -1.88 to -0.05, p=0.039) and HF-related mortality (OR=0.68, 95% CI 0.54 to 0.85, p=0.001) were significantly lower in the teletransmission group, as opposed to the standard care group, whereas only HF-related admission rate (OR=0.64, 95% CI 0.52 to 0.79, p<0.001) was lower in the telephone-supported care group. Overall, telemedicine was shown to be beneficial, with home-based teletransmission effectively reducing all-cause mortality and HF-related hospital admission, length of stay and mortality in patients with HF.

Disruption of calcium homeostasis by cardiac-specific over-expression of PPAR-γ in mice: A role in ventricular arrhythmia.

AIMS: Adverse cardiovascular effects induced by peroxisome proliferator activator receptor-γ (PPAR-γ) activation were observed in clinical setting. But the underlying mechanism is unclear. Now, transgenic mice with cardiac specific peroxisome proliferator activator receptor-γ overexpression (TG-PPAR-γ) were used to explore the possible mechanisms. MATERIALS AND METHODS: Cardiac tissues from TG-PPAR-γ mice, a PPAR-γ over-expressing human cardiomyocyte line AC16 cell, and PPAR-γ agonist-treated primary cardiomyocytes were used to evaluate the expression of cardiac calcium regulatory proteins as sarcoplasmic reticulum Ca2+ ATPase, Na+/Ca2+ exchanger 1, ryanodine receptor 2 and phospholamban. Intracellular Ca2+ levels were also examined by flow cytometry and confocal microscopy with Fluo-4/AM in these cells. KEY FINDINGS: In this study, frequent ventricular premature contraction and polymorphic ventricular tachycardia were observed in TG-PPAR-γ but not in wild-type mice. Besides, we found the calcium regulatory proteins expression were higher in the TG-PPAR-γ mice, PPAR-γ overexpressing human cardiomyocyte line AC16 cell and PPAR-γ agonist-treated primary cardiomyocytes than the control group respectively. In addition, an increase of intracellular calcium levels and CaMKII δ expression in PPAR-γ overexpression and PPAR-γ activation group. Moreover, Inhibition of CaMKII δ could improve the intracellular calcium levels and reduce the occurrence of ventricular arrhythmia. SIGNIFICANCE: PPAR-γ over-expression perturbs the intracellular calcium homeostasis in cardiomyocytes which contribute to the ventricular arrhythmias and cardiac sudden death in TG-PPAR-γ mice.

Effects of C-reactive protein on K(+) channel interaction protein 2 in cardiomyocytes.

Several studies have found that C-reactive protein (CRP) was associated with QTc interval prolongation and ventricular arrhythmia. However, little is known about the mechanisms involved. K(+) channel interaction protein 2 (KChIP2) is a necessary subunit for the formation of transient outward potassium current (Ito.f) which plays a critical role in early repolarization and QTc interval of heart. In this study, we aimed to evaluate the effects of CRP on KChIP2 and Ito.f in cardiomyocytes and to explore the potential mechanism. The neonatal mice ventricular cardiomyocytes were cultured and treated with CRP at different concentrations. The expression of KChIP2 was detected by real time quantitative PCR and Western blot. In addition, Ito.f current density was evaluated by whole cell patch clamp techniques. Our results showed that CRP significantly decreased the mRNA and protein expression of KChIP2 in time and doses dependent manners (P < 0.05), and also reduced the current density of Ito.f (P < 0.05). In addition, CRP increased the expression of NF-κB and decreased IκBα expression without significant influence on the expression of ERK1/2 and JNK. Meanwhile, the NF-κB inhibitor PDTC significantly attenuated the effects of CRP on KChIP2 and Ito.f current density. In conclusion, CRP could significantly down-regulate KChIP2 expression and reduce current density of Ito.f partly through NF-κB pathway, suggesting that CRP may directly or indirectly influence QTc interval and arrhythmia via influencing KChIP2 expression and Ito.f current density of cardiomyocytes.

Effects of cardiac resynchronization therapy on left ventricular remodeling and dyssynchrony in patients with left ventricular noncompaction and heart failure.

Left ventricular noncompaction (LVNC) is a rare cardiomyopathy with high incidence of heart failure (HF). It is unclear whether LVNC patients with desynchronized HF would benefit from cardiac resynchronization therapy (CRT). In order to evaluate the effect of CRT on LVNC, this study explored left ventricular (LV) remodeling and mechanical synchronicity before and after CRT in LVNC patients, and compare with that in idiopathic dilated cardiomyopathy (DCM) patients. We collected 15 LVNC and 30 matched DCM patients. All the patients underwent clinical evaluation,electrocardiogram and echocardiography before CRT and ≥6 months later. LV response was defined as ≥15 % decrease in LV end-systolic volume (LVESV). Longitudinal synchronicity was quantified by YU-index using tissue Doppler imaging. The time delay of peak radial strain from anteroseptal to posterior wall, which derived from speckle tracking imaging, was used to quantify radial synchronicity. In LVNC group, LV ejection fraction increased from 27.6 ± 5.5 to 39.1 ± 7.0 % (P < 0.01) during follow-up, but LV volumes did not change significantly (both P > 0.05). Five LVNC patients (33.3 %) responded to CRT, and all of them were super-responders (reduction in LVESV > 30 %). In addition, the number of noncompacted segments and the thickness ratio of noncompacted to compacted myocardium decreased (both P < 0.05). Inter-ventricular, longitudinal and radial intra-ventricular dyssynchrony also reduced significantly (all P < 0.05). Compared with DCM group, there was no significant difference in LV response rate (33.3 vs. 60.0 %, P = 0.092), improvement of LV function and dyssynchrony index (all P < 0.05). In conclusion, CRT improved heart function, morphology and mechanical dyssynchrony in LVNC patients.

Potential proarrhythmic effect of cardiac resynchronization therapy during perioperative period: data from a single cardiac center.

BACKGROUND: Cardiac resynchronization therapy (CRT) could improve heart function, symptom status, quality of life and reduce hospitalization and mortality in patients with severe heart failure (HF) with optimal medical management. However, the possible adverse effects of CRT are often ignored by clinicians. METHOD: A retrospective analysis of CRT over a 6-year period was made in a single cardiac center. RESULTS: Fifty-four patients were treated with CRT(D) device, aged (57 ± 11) years, with left ventricular ejection fraction of (32.1 ± 9.8)%, of which 4 (7%) developed ventricular tachycardia/ventricular fibrillation (VT/VF) or junctional tachycardia after operation. Except for one with frequent ventricular premature beat before operation, the others had no previous history of ventricular arrhythmia. Of the 4 patients, 3 had dilated cardiomyopathy and 1 had ischemic cardiomyopathy, and tachycardia occurred within 3 days after operation. Sustained, refractory VT and subsequent VF occurred in one patient, frequent nonsustained VT in two patients and nonparoxysmal atrioventricular junctional tachycardia in one patient. VT was managed by amiodarone in two patients, amiodarone together with beta-blocker in one patient, and junctional tachycardia was terminated by overdrive pacing. During over 12-month follow-up, except for one patient's death due to refractory heart and respiratory failure in hospital, the others remain alive and arrhythmia-free. CONCLUSIONS: New-onset VT/VF or junctional tachycardia may occur in a minority of patients with or without prior history of tachycardia after biventricular pacing. Arrhythmia can be managed by conventional therapy, but may require temporary discontinuation of pacing. More observational studies should be performed to determine the potential proarrhythmic effect of CRT.

[The expression and significance of activator protein-1 and matrix metalloproteinases in the human heart post acute myocardial infarction].

OBJECTIVE: To investigate the expression and significance of activator protein-1 (AP-1) and matrix metalloproteinases (MMPs) in acute myocardial infarction (AMI) subjects. METHODS: Immunohistochemical techniques were used to detect the subunit of AP-1 (c-Jun), MMP-2 and MMP-9 in human AMI and normal heart tissue and the expressions of c-Jun and MMPs were measured with computer image analysis system. RESULTS: (1) There were expressions of c-Jun, MMP-2 and MMP-9 in normal heart tissue, mainly in myocardial cells and cardiac fibroblasts, and their expressions in AMI myocardial tissues were all significantly higher than those in normal myocardial tissues (P < 0.05). (2) The level of MMP-9 expression was significantly and positively correlated with c-Jun in AMI heart tissue (r = 0.773, P < 0.01). CONCLUSIONS: The expressions of AP-1 and MMPs increase in human myocardial infarction. These findings suggest that AP-1 transcription activation pathway and MMPs may play an important role in ventricular remodeling of myocardial infarction.

[Clinical analysis of inappropriate shock of implantable cardioverter defibrillators].

OBJECTIVE: Implantable cardioverter defibrillator (ICD) can effectively treat life-threatening ventricular arrhythmias. The most common side effect is inappropriate discharge. This study analyzes the incidence and causes of inappropriate discharges of ICD in our hospital. METHODS: Forty-three patients implanted with ICD in our hospital from November 2001 to October 2007 were involved in our study. Patients were followed-up regularly. All episodes recorded and stored in the ICD were analyzed. RESULTS: Seven of the 43 patients underwent ninety-six inappropriate discharges. Inappropriate discharges in six patients were caused by supraventricular tachyarrhythmias (SVT). In one patient the discharge was caused by noise. Most inappropriate discharges occurred in the first year after implantation. The history of atrial fibrillation before implantation is an independent predictor of inappropriate discharges. CONCLUSIONS: The incidence of inappropriate discharge is 16.3% in our study and the most common cause is SVT. Most inappropriate discharges occur in the first year after implantation. Patients with atrial fibrillation history have a higher risk of inappropriate discharges.

R25G mutation in exon 1 of LMNA gene is associated with dilated cardiomyopathy and limb-girdle muscular dystrophy 1B.

BACKGROUND: Mutations of the LMNA gene encoding lamin A and C are associated with dilated cardiomyopathy (DCM), conduction system defects and skeletal muscle dystrophy. Here we report a family with a mutation of the LMNA gene to identify the relationship between genotype and phenotype. METHODS: All 30 members of the family underwent clinical and genetic evaluation. A mutation analysis of the LMNA gene was performed. All of the 12 exons of LMNA gene were extended with polymerase chain reaction (PCR) and the PCR products were screened for gene mutation by direct sequencing. RESULTS: Ten members of the family had limb-girdle muscular dystrophy (LGMD) and 6 are still alive. Two patients suffered from DCM. Cardiac arrhythmias included atrioventricular block and atrial fibrillation; sudden death occurred in 2 patients. The pattern of inheritance was autosomal dominant. Mutation c.73C > G (R25G) in exon 1 encoding the globular domains was confirmed in all of the affected members, resulting in the conversion of arginine (Arg) to glycine (Gly). CONCLUSIONS: The mutation R25G in exon 1 of LMNA gene we reported here in a Chinese family had a phenotype of malignant arrhythmia and mild LGMD, suggesting that patients with familial DCM, conduction system defects and skeletal muscle dystrophy should be screened by genetic testing for the LMNA gene.

[Effect of AP-1 decoy oligodeoxynucleotides on neonatal rat cardiac fibroblast proliferation and collagen synthesis].

OBJECTIVE: To investigate the inhibitory effects of AP-1 decoy oligodeoxynucleotides (ODNs) on angiotensin II (AngII)-induced proliferation and collagen synthesis in neonatal rat cardiac fibroblasts (CFs). METHODS: The CFs of neonatal SD rats were cultured in serum-free medium for 24 h and stimulated with 10(-7) mol/L AngII in the presence of AP-1 decoy ODNs or mutational AP-1 decoy ODNs at varied concentrations. MTT assay was employed for quantitative evaluation of the CF proliferation. Collagen synthesis in the CFs was assessed with hydroxyproline, and the cell cycle distribution determined with flow cytometry (FCM). RESULTS: With the increase of the concentration of AP-1 decoy ODNs, the absorbance at 490 nm (OD490) of the CFs decreased gradually as shown by MTT assay. Treatment with 100 or 200 nmol/L AP-1 decoy ODNs resulted in significantly lowered OD490 of the CFs as compared with that of AngII group. The concentration of hydroxyproline increased significantly after treatment with 10(-7) mol/L AngII in comparison with the control group (P<0.05). Hydroxyproline concentration in cells treated with 100 or 200 nmol/L AP-1 decoy ODNs was significantly lower than that in the 10(-7) mol/L AngII-treated cells. AP-1 decoy ODNs decreased the cell percentage in S phase and increased hydroxyproline concentration, but increased the percentage of cells in G0/G1 phase. AP-1 decoy ODNs at 100 and 200 nmol/L did not obviously affect AngII-induced CF proliferation and collagen synthesis (P<0.01). CONCLUSION: AP-1 decoy can inhibit AngII-induced rat CF proliferation and collagen synthesis possibly by affecting the cell cycle distribution.