β3 adrenergic receptor antagonist SR59230A exerts beneficial effects on right ventricular performance in monocrotaline-induced pulmonary arterial hypertension

Vaccarin Ameliorates Doxorubicin-Induced Cardiotoxicity via Inhibition of p38 MAPK Mediated Mitochondrial Dysfunction

Doxorubicin is a frequently used chemotherapeutic agent for treating various malignancies. However, it leads to severe cardiotoxic side effects, such as heart failure, and elevates the risk of sudden cardiac death among cancer patients. While oxidative stress has been identified as the primary cause of doxorubicin-induced cardiotoxicity, therapeutic antioxidant approaches have yielded unsatisfactory outcomes. The aim of this study is to explore the therapeutic potential of vaccarin, an active flavonoid glycoside extracted from traditional Chinese herbal agent Semen Vaccariae, in doxorubicin-induced cardiotoxicity. We observed that vaccarin significantly ameliorates doxorubicin-induced heart dysfunction in mouse model and suppresses oxidative stress mediated cell apoptosis via specifically inhibiting the activation of p38 MAPK pathway. In vitro, we observed that vaccarin alleviates doxorubicin-induced mitochondrial membrane depolarization and ROS generation in H9c2 cell, but the p38 MAPK agonist anisomycin reverses these effects. Our findings provide a promising natural antioxidant to protect against DOX-induced cardiotoxicity.

β3 adrenoceptor agonist mirabegron protects against right ventricular remodeling and drives Drp1 inhibition

Background

The right ventricular (RV) function determines the prognosis of patients with pulmonary hypertension (PH). Metabolic disorders have been observed in the RV myocardium in PH. Activation of the β3 adrenoceptor improves cardiac function and restores cardiac metabolic efficiency in rodents with heart failure; however, its role in the RV remains uncertain.

Methods

Experimental PH was induced by monocrotaline (MCT) in rats. Mirabegron, a selective β3 adrenoceptor agonist, was given to MCT rats daily from the day after MCT injection at the dose of 10 mg/kg. In vivo echocardiography and RV catheterization were performed to assess RV hemodynamics, structure, and function. RV fibrosis and hypertrophy were assessed by Sirius Red (SR) and wheat germ agglutinin (WGA) staining respectively. Western blotting was performed to examine the markers of RV fibrosis and hypertrophy, as well as the levels of the key molecules and their phosphorylated forms. The molecular changes were confirmed in the cardiac hypertrophy model of angiotensin II (Ang II) treated H9c2 cardiomyocytes using western blotting.

Results

The overloaded RV had increased β3 adrenoceptor expression, which was further increased by mirabegron. Mirabegron reduced RV pressure and reduced RV structural and functional deterioration in MCT rats. Mirabegron decreased cardiac fibrosis and hypertrophy in the overloaded RV. Mirabegron suppressed dynaminrelated protein 1 (Drp1) and promoted AMP-activated protein kinase (AMPK) signaling in the overloaded RV and Ang II treated cardiomyocytes.

Conclusions

The β3 adrenoceptor agonist mirabegron reduced RV hypertrophy and fibrosis in PH rats. The treatment effect involved Drp1 inhibition and AMPK activation.

β3 adrenergic receptor as potential therapeutic target in ADPKD

Autosomal dominant polycystic kidney disease (ADPKD) disrupts renal parenchyma through progressive expansion of fluid-filled cysts. The only approved pharmacotherapy for ADKPD involves the blockade of the vasopressin type 2 receptor (V2R). V2R is a GPCR expressed by a subset of renal tubular cells and whose activation stimulates cyclic AMP (cAMP) accumulation, which is a major driver of cyst growth. The β3-adrenergic receptor (β3-AR) is a GPCR expressed in most segments of the murine nephron, where it modulates cAMP production. Since sympathetic nerve activity, which leads to activation of the β3-AR, is elevated in patients affected by ADPKD, we hypothesize that β3-AR might constitute a novel therapeutic target. We find that administration of the selective β3-AR antagonist SR59230A to an ADPKD mouse model (Pkd1fl/fl ;Pax8rtTA ;TetO-Cre) decreases cAMP levels, producing a significant reduction in kidney/body weight ratio and a partial improvement in kidney function. Furthermore, cystic mice show significantly higher β3-AR levels than healthy controls, suggesting a correlation between receptor expression and disease development. Finally, β3-AR is expressed in human renal tissue and localizes to cyst-lining epithelial cells in patients. Thus, β3-AR is a potentially interesting target for the development of new treatments for ADPKD.

SOX17 Loss-of-Function Mutation Underlying Familial Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) refers to a rare, progressive disorder that is characterized by occlusive pulmonary vascular remodeling, resulting in increased pulmonary arterial pressure, right-sided heart failure, and eventual death. Emerging evidence from genetic investigations of pediatric-onset PAH highlights the strong genetic basis underpinning PAH, and deleterious variants in multiple genes have been found to cause PAH. Nevertheless, PAH is of substantial genetic heterogeneity, and the genetic defects underlying PAH in the overwhelming majority of cases remain elusive. In this investigation, a consanguineous family suffering from PAH transmitted as an autosomal-dominant trait was identified. Through whole-exome sequencing and bioinformatic analyses as well as Sanger sequencing analyses of the PAH family, a novel heterozygous SOX17 mutation, NM_022454.4: c.379C>T; p. (Gln127*), was found to co-segregate with the disease in the family, with complete penetrance. The nonsense mutation was neither observed in 612 unrelated healthy volunteers nor retrieved in the population genetic databases encompassing the Genome Aggregation Database, the Exome Aggregation Consortium database, and the Single Nucleotide Polymorphism database. Biological analyses using a dual-luciferase reporter assay system revealed that the Gln127*-mutant SOX17 protein lost the ability to transcriptionally activate its target gene NOTCH1. Moreover, the Gln127*-mutant SOX17 protein exhibited no inhibitory effect on the function of CTNNB1-encode β-catenin, which is a key player in vascular morphogenesis. This research firstly links SOX17 loss-of-function mutation to familial PAH, which provides novel insight into the molecular pathogenesis of PAH, suggesting potential implications for genetic and prognostic risk evaluation as well as personalized prophylaxis of the family members affected with PAH.

Neurohormonal Modulation as a Therapeutic Target in Pulmonary Hypertension

The autonomic nervous system (ANS) and renin-angiotensin-aldosterone system (RAAS) are involved in many cardiovascular disorders, including pulmonary hypertension (PH). The current review focuses on the role of the ANS and RAAS activation in PH and updated evidence of potential therapies targeting both systems in this condition, particularly in Groups 1 and 2. State of the art knowledge in preclinical and clinical use of pharmacologic drugs (beta-blockers, beta-three adrenoceptor agonists, or renin-angiotensin-aldosterone signaling drugs) and invasive procedures, such as pulmonary artery denervation, is provided.