NPS2143 Modulates the Phenotypic Switching of PASMCs by Inhibiting Autophagy in Hypoxia-Induced Pulmonary Hypertension

Background and Objectives: Pulmonary Artery Hypertension (PAH) is considered as a malignant tumor in cardiovascular disease. Our previous study found that Calcium-Sensing Receptor (CaSR) is involved in pulmonary vascular remodeling in hypoxic pulmonary hypertension (HPH). However, the relationship of Pulmonary Artery Smooth Muscle Cell (PASMC) phenotypic switching, proliferation, and autophagy in CaSR-related HPH remain unclear. The purpose of this study was to detect the role of a CaSR antagonist, NPS2143, on the vascular remodeling by autophagy modulation under hypoxia. Methods: Hypoxic rat PAH model were simulated in vivo. Meanwhile, mean Pulmonary Artery Pressure (mPAP) was measured while RVI, WT%, and WA% indices were calculated. Immunohistochemistry and Western blot were used to detect phenotypic switching and cell proliferation in pulmonary arteriole. Cell viability was determined in vitro by CCK8 and cell cycle. Cell proliferation, phenotypic switching, autophagy level and PI3K/Akt/mTOR pathways were investigated in human PASMCs through mRNA or Western blot methods. Results: Rats with hypoxic-induced PAH had an increased mPAP, RVI, WT% and WA%. Moreover, expression of CaSR was significantly increased, followed by activation of autophagy (increased LC3b and decreased p62), phenotypic switching of PASMCs (reduced calponin, SMA-a and increased OPN) and pulmonary vascular remodeling. However, NPS2143 weakened these hypoxic effects. The results using hypoxic-induced human PASMCs confirmed that NPS2143 suppressed autophagy and reversed phenotypic switching in vitro by inhibiting PI3K/Akt/mTOR pathways. Conclusions: Our study demonstrates that NPS2143 was conducive to inhibit the proliferation and reverse phenotypic switching of PASMCs by regulating autophagy levels in HPH and vascular remodeling.