No abstract

No abstract

Diabetic cardiomyopathy, which refers to the destruction of the structure and function of the heart, is the primary cause of heart failure due to diabetes. LCZ696 is the first angiotensin receptor-neprilysin inhibitor (ARNi) to be used clinically. Our study investigated the role played by LCZ696 during diabetic cardiomyopathy and explored the potential mechanisms underlying these effects. Diabetes was induced by injecting streptozotocin intraperitoneally into mice, and the mice were then divided randomly into two groups: one group was treated with LCZ696 (60 mg/kg/d) for 16 weeks, and the other received no treatment. The H9C2 cardiomyoblast cell line was treated with LCZ696 under high-glucose (HG) conditions. The levels of apoptotic (Bax, Bcl-2 and cleaved caspase-3) and pro-inflammatory factors [nuclear factor (NF)-κB, c-Jun N-terminal kinase (JNK) and p38 mitogen-activated kinase (MAPK)] were assessed in heart tissues from diabetic and normal mice and in H9C2 cells. The heart tissue structures and cardiac functions of diabetic mice were compared with those of normal mice, using histological and echocardiographic analyses. The results showed that LCZ696 inhibits the nuclear transfer of NF-κB and JNK/p38MAPK phosphorylation, and mitigates inflammation and apoptosis in diabetic mice and H9C2 cardiomyocytes under HG conditions. The histological and echocardiographic data showed that compared with untreated diabetic mice, diabetic mice treated with LCZ696 exhibited improved ventricular remodeling and cardiac function. LCZ696 also ameliorated oxidative stress in both vivo and vitro. In conclusion, LCZ696 improved diabetic cardiomyopathy by reducing cardiac inflammation, oxidative stress, and apoptosis. Impact statement Diabetic cardiomyopathy (DCM) is an important cause of heart failure in patients with diabetes, resulting in increased morbidity and mortality. LCZ696, which was studied here, is a novel drug for the treatment of heart failure. The latest research reports that LCZ696 is more effective for preventing heart failure than valsartan alone. However, little research has been performed examining the effects of LCZ696 on DCM. This study was designed to examine the role played by LCZ696 during DCM and the potential mechanisms underlying these effects, which may provide the basis for a new therapeutic strategy for DCM.

BackgroundPulmonary arterial hypertension (PAH) is commonly accompanied with the activation of the renin-angiotensin-aldosterone system (RAAS). Renal sympathetic denervation (RSD) reduces PAH partly through the inhibition of RAAS. Analogically, we hypothesized that pulmonary artery denervation (PADN) could reverse PAH and PAH-induced right ventricular (RV) dysfunction by downregulating the local RAAS activity.MethodsTwenty-five beagle dogs were randomized into two groups: control group (intra-atrial injection of N-dimethylacetamide, 3 mg/kg, n = 6) and test group (intra-atrial injection of dehydrogenized-monocrotaline, 3 mg/kg, n = 19). Eight weeks later, dogs in the test group with mean pulmonary arterial pressure (mPAP) ≥25 mmHg (n = 16) were reassigned into the sham (n = 8) and PADN groups (n = 8) by chance. After another 6 weeks, the hemodynamics, pulmonary tissue morphology and the local RAAS expression in lung and right heart tissue were measured.ResultsPADN reduced the mPAP (25.94 ± 3.67 mmHg vs 33.72 ± 5.76 mmHg, P < 0.05) and the percentage of medial wall thickness (%MWT) (31.0 ± 2.6 % vs 37.9 ± 2.8 %, P < 0.05) compared with the sham group. PADN attenuated RV dysfunction, marked with reduced atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and ratio of right ventricular to left ventricular plus septum weight [RV/(LV + S)]. Moreover, the local RAAS expression was activated in PAH dogs while inhibited after PADN.ConclusionsPADN improves hemodynamics and relieves RV dysfunction in dogs with PAH, which can be associated with the downregulating RAAS activity in local tissue.

Cardiac hypertrophy and ventricular remodeling following heart failure are important causes of high mortality in heart disease patients. The cardiac lymphatic system has been associated with limited research, but it plays an important role in the improvement of myocardial edema and the promotion of fluid balance. LCZ696 is a novel combination of angiotensin and neprilysin inhibitors. Here, we studied the role played by LCZ696 during transverse aortic constriction (TAC) induced cardiac hypertrophy and changes in the lymphatic system. Mice undergoing aortic coarctation were constructed to represent a cardiac hypertrophy model and then divided into random groups that either received treatment with LCZ696 (60 mg/kg/d) or no treatment. Cardiac ultrasonography was used to detect cardiac function, and hematoxylin and eosin (H&E) and Masson staining were used to detect myocardial hypertrophy and fibrosis. The proinflammatory factors interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α) were detected in the blood and heart tissues of mice. The protein expression levels of lymphatic-specific markers, such as vascular endothelial growth factor C (VEGF-C), VEGF receptor 3 (VEGFR3), and lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1) were detected in mouse heart tissues. We also examined the colocalization of lymphatic vessels and macrophages by immunofluorescence. The results showed that LCZ696 significantly improved heart dysfunction, cardiac hypertrophy, and fibrosis and inhibited the expression of proinflammatory factors IL-6, IL-1β, and TNF-α in the circulating blood and heart tissues of mice. LCZ696 also decreased the protein expression levels of VEGF-C, VEGFR3, and LYVE-1 in mouse heart tissues, ameliorated the transport load of lymphatic vessels to macrophages, and improved the remodeling of the lymphatic system in the hypertrophic cardiomyopathy model induced by TAC.

BackgroundIvabradine (IVBD), a novel I(f)-channel inhibitor and specific heart rate-lowering agent, is known to have anti-oxidative activity that promotes endothelial function. However, the molecular mechanism through which IVBD acts on cardiac function has yet to be elucidated, especially in experimental diabetic animals.MethodsFor this reason, twenty diabetic mice were randomly assigned to IVBD-treated (10 mg/kg/day) and control (saline) groups. After a 3-month treatment, microarray assay was performed to identify differentia expressed genes, and cardiac function was measured by echocardiography, with subsequent immunohistochemistry analysis and western blotting.ResultsOur results showed that ivabradine treatment attenuated the expression and staining score of matrix metalloproteinase (MMP)-2, induced the dephosphorylation of caspase 3, BAX and MMP-2, and enhanced the phosphorylation of NF-κB. Ivabradine treatment led to a significant improvement in cardiac function.ConclusionIvabradine significantly improved cardiac function by attenuating apoptosis and inhibiting the expression and activity of MMP-2 in diabetic mice, which underscored the novel clinical implications of ivabradine for diabetic patients.

This study aimed to investigate the effects and molecular mechanisms of ivabradine in preventing cardiac hypertrophy in an established transverse aortic constriction (TAC) mouse model. A total of 56 male C57BL/6 mice were randomly assigned into the following seven groups (8 mice per group): sham, TAC model, Iva-10 (10 mg/kg/day ivabradine), Iva-20 (20 mg/kg/day ivabradine), Iva-40 (40 mg/kg/day ivabradine), Iva-80 (80 mg/kg/day ivabradine), and Rap (rapamycin, a positive control). Echocardiography and left ventricular hemodynamics were performed. Hematoxylin-eosin (H&E), Masson's trichome staining, and TUNEL assays were conducted to evaluate cardiac hypertrophy, fibrosis, and apoptosis, respectively. Western blotting was performed to detect the expression of proteins related to the PI3K/Akt/mTOR/p70S6K pathway. Ivabradine could effectively improve left ventricular dysfunction and hypertrophy induced by TAC in a dose-independent manner. Moreover, no obvious change in heart rate (HR) was observed in the TAC and Rap groups, whereas a significant decrease in HR was found after ivabradine treatment (P < 0.05). Cardiac hypertrophy, fibrosis, and apoptosis induced by TAC were notably suppressed after either rapamycin or ivabradine treatment (P < 0.05). Ivabradine and rapamycin also decreased the expression of PI3K/Akt and mTOR induced by TAC. Ivabradine improved cardiac hypertrophy and fibrosis as well as reduced cardiomyocyte apoptosis via the PI3K/Akt/mTOR/p70S6K pathway in TAC model mice.

Recent studies reported that atorvastatin (ATOR) alleviated progression of experimental diabetic cardiomyopathy (DCM), possibly by protecting against apoptosis. However, the underlying mechanisms of this protective effect remain unclear. Therefore, our study investigated the role of the glycogen synthase kinase (GSK)-3β-protein phosphatase 2A(PP2A)-NF-κB signaling pathway in the anti-apoptotic and cardioprotective effects of ATOR on cardiomyocytes cultured in high glucose (HG) and in DCM. Our results showed that, in HG-cultured cardiomyocytes, phosphorylation of GSK-3β was decreased, while that of the PP2A catalytic subunit C (PP2Ac) and IKK/IкBα was increased, followed by NF-кB nuclear translocation and apoptosis. IKK/IкBα phosphorylation and NF-кB nuclear translocation were also increased by treatment of cells with okadaic acid (OA), a selective PP2A inhibitor, or by silencing PP2Ac expression. The opposite results were obtained by silencing GSK-3β expression, which resulted in PP2Ac activation. Furthermore, IKK/IкBα phosphorylation and NF-кB nuclear translocation were markedly inhibited and apoptosis attenuated in cells treated with ATOR. These effects occurred through inactivation of GSK-3β and subsequent activation of PP2Ac. They were abolished by treatment of cells with OA or PP2Ac siRNA. In mice with type 1 diabetes mellitus, treatment with ATOR, at 10 mg-kg−1-d−1, significantly suppressed GSK-3β activation, IKK/IкBα phosphorylation, NF-кB nuclear translocation and caspase-3 activation, while also activating PP2Ac. Finally, improvements in histological abnormalities, fibrosis, apoptosis and cardiac dysfunction were observed in diabetic mice treated with ATOR. These findings demonstrated that ATOR protected against HG-induced apoptosis in cardiomyocytes and alleviated experimental DCM by regulating the GSK-3β-PP2A-NF-κB signaling pathway.