Effects of Low-Dose Sacubitril/Valsartan on Different Stages of Cardiac Hypertrophy in Salt-Loaded Hypertensive Rats

Sacubitril/valsartan reverses cardiac structure and function in experimental model of hypertension-induced hypertrophic cardiomyopathy

This study evaluated the effect of sacubtril/valsartan on cardiac remodeling, molecular and cellular adaptations in experimental (rat) model of hypertension-induced hypertrophic cardiomyopathy. Thirty Wistar Kyoto rats, 10 healthy (control) and 20 rats with confirmed hypertension-induced hypertrophic cardiomyopathy (HpCM), were used for this study. The HpCM group was further subdivided into untreated and sacubitril/valsartan-treated groups. Myocardial structure and function were assessed using echocardiography, Langendorff's isolated heart experiment, blood sampling and qualitative polymerase chain reaction. Echocardiographic examinations revealed protective effects of sacubitril/valsartan by improving left ventricular internal diameter in systole and diastole and fractional shortening. Additionally, sacubitril/valsartan treatment decreased systolic and diastolic blood pressures in comparison with untreated hypertensive rats. Moreover, sacubitril/valsartan treatment reduced oxidative stress and apoptosis (reduced expression of Bax and Cas9 genes) compared to untreated rats. There was a regular histomorphology of cardiomyocytes, interstitium, and blood vessels in treated rats compared to untreated HpCM rats which expressed hypertrophic cardiomyocytes, with polymorphic nuclei, prominent nucleoli and moderately dilated interstitium. In experimental model of hypertension-induced hypertrophic cardiomyopathy, sacubitril/valsartan treatment led to improved cardiac structure, haemodynamic performance, and reduced oxidative stress and apoptosis. Sacubitril/valsartan thus presents as a potential therapeutic strategy resulted in hypertension-induced hypertrophic cardiomyopathy.

Preventive effect of LCZ696 on hypoxic pulmonary hypertension in rats via regulating the PI3K/AKT signaling pathway

Hypoxic pulmonary hypertension (HPH) is a devastating disease worldwide; however, effective therapeutic drugs are lacking. This study investigated the effects and underlying mechanisms of LCZ696 treatment on hypoxia-induced pulmonary hypertension. Male Sprague-Dawley (SD) rats were kept in a hypobaric chamber with an oxygen concentration of 5% for 4 weeks. Rats were treated with either LCZ696 (18 mg/kg, 36 mg/kg, and 72 mg/kg) or sildenafil. The mean pulmonary artery pressure (mPAP), right ventricle hypertrophy index (RVHI), and lung system index were measured. Hematoxylin-eosin (HE) staining, Masson staining, and immunofluorescence staining were used for histological analysis. Enzyme linked immunosorbent assay (ELISA) kits were used to determine the concentrations of inflammatory and hypoxia-related factors. Western blotting was used to examine the expression of apoptotic and PI3K/AKT signaling pathway proteins in rat lung tissue. Hypoxia increased mPAP, RVHI, and lung system index and induced pulmonary vascular remodeling, pulmonary arteriomyosis, and pulmonary artery fibrosis. LCZ696 treatment reduced the increase in mPAP, RVHI, and the lung system index and ameliorated the induced pathological changes. Hypoxia upregulated expression of NF-kB, TNF-α, IL-6, HIF-1α, and Vascular endothelial growth factor (VEGF), decreased the ratio of Bax/Bcl-2, and activated the PI3K/AKT signaling pathway in lung tissue, and these effects were partially reversed by treatment with LCZ696. These results demonstrated that LCZ696 can ameliorate hypoxia-induced HPH by suppressing apoptosis, inhibiting the inflammatory response, and inhibiting the PI3K/AKT signaling pathway. It provides a reference for clinical rational drug use and lays a foundation for the study of HPH therapeutic drugs.

Neprilysin Inhibition in the Prevention of Anthracycline-Induced Cardiotoxicity

Anthracycline-induced cardiotoxicity (AIC) poses a clinical challenge in the management of cancer patients. AIC is characterized by myocardial systolic dysfunction and remodeling, caused by cardiomyocyte DNA damage, oxidative stress, mitochondrial dysfunction, or renin-angiotensin-aldosterone system (RAAS) dysregulation. In the past decade, after positive results of a PARADIGM-HF trial, a new class of drugs, namely angiotensin receptor/neprilysin inhibitors (ARNi), was incorporated into the management of patients with heart failure with reduced ejection fraction. As demonstrated in a variety of preclinical studies of cardiovascular diseases, the cardioprotective effects of ARNi administration are associated with decreased oxidative stress levels, the inhibition of myocardial inflammatory response, protection against mitochondrial damage and endothelial dysfunction, and improvement in the RAAS imbalance. However, data on ARNi's effectiveness in the prevention of AIC remains limited. Several reports of ARNi administration in animal models of AIC have shown promising results, as ARNi prevented ventricular systolic dysfunction and electrocardiographic changes and ameliorated oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress, and the inflammatory response associated with anthracyclines. There is currently an ongoing PRADAII trial aimed to assess the efficacy of ARNi in patients receiving breast cancer treatment, which is expected to be completed by late 2025.

Molecular mechanisms of sacubitril/valsartan in cardiac remodeling

Cardiovascular diseases have become a major clinical burden globally. Heart failure is one of the diseases that commonly emanates from progressive uncontrolled hypertension. This gives rise to the need for a new treatment for the disease. Sacubitril/valsartan is a new drug combination that has been approved for patients with heart failure. This review aims to detail the mechanism of action for sacubitril/valsartan in cardiac remodeling, a cellular and molecular process that occurs during the development of heart failure. Accumulating evidence has unveiled the cardioprotective effects of sacubitril/valsartan on cellular and molecular modulation in cardiac remodeling, with recent large-scale randomized clinical trials confirming its supremacy over other traditional heart failure treatments. However, its molecular mechanism of action in cardiac remodeling remains obscure. Therefore, comprehending the molecular mechanism of action of sacubitril/valsartan could help future research to study the drug’s potential therapy to reduce the severity of heart failure.

A novel mouse model of obstructive sleep apnea by bulking agent-induced tongue enlargement results in left ventricular contractile dysfunction

AIMS

Obstructive sleep apnea (OSA) is a widespread disease with high global socio-economic impact. However, detailed pathomechanisms are still unclear, partly because current animal models of OSA do not simulate spontaneous airway obstruction. We tested whether polytetrafluoroethylene (PTFE) injection into the tongue induces spontaneous obstructive apneas.

METHODS AND RESULTS

PTFE (100 μl) was injected into the tongue of 31 male C57BL/6 mice and 28 mice were used as control. Spontaneous apneas and inspiratory flow limitations were recorded by whole-body plethysmography and mRNA expression of the hypoxia marker KDM6A was quantified by qPCR. Left ventricular function was assessed by echocardiography and ventricular CaMKII expression was measured by Western blotting. After PTFE injection, mice showed features of OSA such as significantly increased tongue diameters that were associated with significantly and sustained increased frequencies of inspiratory flow limitations and apneas. Decreased KDM6A mRNA levels indicated chronic hypoxemia. 8 weeks after surgery, PTFE-treated mice showed a significantly reduced left ventricular ejection fraction. Moreover, the severity of diastolic dysfunction (measured as E/e') correlated significantly with the frequency of apneas. Accordingly, CaMKII expression was significantly increased in PTFE mice and correlated significantly with the frequency of apneas.

CONCLUSIONS

We describe here the first mouse model of spontaneous inspiratory flow limitations, obstructive apneas, and hypoxia by tongue enlargement due to PTFE injection. These mice develop systolic and diastolic dysfunction and increased CaMKII expression. This mouse model offers great opportunities to investigate the effects of obstructive apneas.