Abstract 14148: Local Aldosterone Production via StAR in PAH and in Human IPS Cell-derived Cardiomyocytes: Efficacy of Spironolactone in Cardiac Remodeling and Mitochondrial Dynamics Under Hypoxic Stress

Abstract

Objective: Pulmonary arterial hypertension (PAH) is a progressive disease that frequently leads to right ventricular (RV) remodeling. Increased plasma aldosterone levels have been reported in patients with PAH. The aim of this study was to examine the expression of steroidogenic acute regulatory protein (StAR) in patients and animal model of PAH, and in the human iPS cell-derived cardiomyocytes (hiPSC-CMs). Furthermore, we evaluated therapeutic effects of mineralocorticoid receptor (MR) antagonist, spironolactone (SPL) on mitochondrial dynamics in the RV myocardium. Methods: Autopsied heart samples (n=20) were obtained from patients with or without PAH. PAH model rats (n=46) were injected with Sugen5416 (20 mg/kg) and then exposed to hypoxia and reoxygenation for 4 weeks with/without treatment with SPL (25 mg/kg/day). Human umbilical vein endothelial cells (HUVECs) and hiPSC-CMs were cultured under hypoxic conditions (37 °C, 1% O 2 , 5% CO 2 ) with/without treatment with SPL (10 μM). In addition, we applied the Clustered Regularly Interspaced Short Palindromic Repeats interference (CRISPRi) technology and repressed StAR gene expression in hiPSC-CMs under hypoxic conditions. Results: In PAH patients, the expression of StAR and MR was significantly increased in cardiomyocytes and endothelial cells in the RV myocardium. In PAH rats, RV systolic pressure elevated over 60 mm Hg with deteriorated RV function. Under electron microscopy, severe degeneration of mitochondria and capillaries with myofibrillar lysis in the RV myocardium were observed, which were compatible with those findings in PAH patients. Hypoxic stress significantly increased the StAR and phosphorylated JNK, ERK-1/2, and NF-kB proteins in hiPSC-CMs as well as in HUVECs. Furthermore, we established the CRISPRi-hiPSC cell lines where StAR gene was successfully knockdown. Treatment with SPL decreased the phosphorylation of JNK, ERK-1/2, NF-kB, and Smad3 in HUVECs and hiPSC-CMs. Strikingly, SPL attenuated mitochondrial degeneration and increased mitophagy, suppressing the RV remodeling under hypoxic stress. Conclusion: SPL might regulate mitochondrial dynamics and attenuates RV remodeling in PAH via StAR/JNK signaling pathway.