Search

Ensuring the homeostatic integrity of pulmonary artery endothelial cells (PAECs) is essential for combatting pulmonary arterial hypertension (PAH), as it equips the cells to withstand microenvironmental challenges. Spermidine (SPD), a potent facilitator of autophagy, has been identified as a significant contributor to PAECs function and survival. Despite SPD's observed benefits, a comprehensive understanding of its protective mechanisms has remained elusive. Through an integrated approach combining metabolomics and molecular biology, this study uncovers the molecular pathways employed by SPD in mitigating PAH induced by monocrotaline (MCT) in a Sprague-Dawley rat model. The study demonstrates that SPD administration (5 mg/kg/day) significantly corrects right ventricular impairment and pathological changes in pulmonary tissues following MCT exposure (60 mg/kg). Metabolomic profiling identified a purine metabolism disorder in MCT-treated rats, which SPD effectively normalized, conferring a protective effect against PAH progression. Subsequent in vitro analysis showed that SPD (0.8 mM) reduces oxidative stress and apoptosis in PAECs challenged with Dehydromonocrotaline (MCTP, 50 μM), likely by downregulating purine nucleoside phosphorylase (PNP) and modulating polyamine biosynthesis through alterations in S-adenosylmethionine decarboxylase (AMD1) expression and the subsequent production of decarboxylated S-adenosylmethionine (dcSAM). These findings advocate SPD's dual inhibitory effect on PNP and AMD1 as a novel strategy to conserve cellular ATP and alleviate oxidative injuries, thus providing a foundation for SPD's potential therapeutic application in PAH treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Pulmonary vascular remodeling (PVR) is the pathological basis of pulmonary hypertension (PH). Incomplete understanding of PVR etiology has hindered drug development for this devastating disease, which exhibits poor prognosis despite the currently available therapies. Endothelial-to-mesenchymal transition (EndMT), a process of cell transdifferentiation, has been recently implicated in cardiovascular diseases, including PH. But the questions of how EndMT occurs and how to pharmacologically target EndMT in vivo have yet to be further answered. Herein, by performing hematoxylin-eosin and immunofluorescence staining, transmission electron microscopy and Western blotting, we found that EndMT plays a key role in the pathogenesis of PH, and importantly that aspirin, a FDA-approved widely used drug, was capable of ameliorating PVR in a preclinical rat model of hypoxia-induced PH. Moreover, aspirin exerted its inhibitory effects on EndMT in vitro and in vivo by suppressing HIF-1α/TGF-β1/Smads/Snail signaling pathway. Our data suggest that EndMT represents an intriguing drug target for the prevention and treatment of hypoxic PH and that aspirin may be repurposed to meet the urgent therapeutic needs of hypoxic PH patients., (Copyright © 2021. Published by Elsevier B.V.)

Pulmonary hypertension (PH) mainly results from excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) and displays mitochondrial abnormalities such as mitochondrial fragmentation. Epigallocatechin-3-gallate (EGCG), an efficient antiproliferative compound in green tea, has recently been demonstrated to inhibit PASMCs proliferation. However, the pre-clinical issues as to whether EGCG attenuates PH and the underlying mechanisms have yet to be addressed. The present study was undertaken to investigate the therapeutic effects of EGCG on PH and its effects on mitochondrial fragmentation in PASMCs. Rats exposed to hypoxia (10% O 2 , 3 weeks) developed PH. EGCG (50, 100 or 200mg/kg/d, i.g.) dose-dependently attenuated right ventricular systolic pressure, pulmonary vascular remodeling and right ventricular hypertrophy, increased expression of mitochondrial fusion protein - mitofusin-2 (MFN-2), and promoted mitochondrial fusion as evidenced by decreased number and volume of mitochondria in PASMCs of pulmonary arteries. Notably, EGCG (50μM) downregulated hypoxia-induced (3% O 2 , 48h) PASMCs mitochondrial fragmentation and inhibited PASMCs proliferation via KLF-4/MFN-2/p-Erk signaling pathway. Collectively, our data demonstrated that EGCG exerts antiproliferative effects via regulating mitochondrial fragmentation of PASMCs and EGCG holds the promise as a drug against PH., (Copyright © 2017. Published by Elsevier B.V.)

The proliferation of pulmonary artery smooth muscle cells (PASMCs) is an important cause of pulmonary vascular remodeling in pulmonary hypertension (PH). It has been reported that miR-137 inhibits the proliferation of tumor cells. However, whether miR-137 is involved in PH remains unclear. In this study, male Sprague-Dawley rats were subjected to 10% O2 for 3 weeks to establish PH, and rat primary PASMCs were treated with hypoxia (3% O2) for 48 h to induce cell proliferation. The effect of miR-137 on PASMC proliferation and calpain-2 expression was assessed by transfecting miR-137 mimic and inhibitor. The effect of calpain-2 on PASMC proliferation was assessed by transfecting calpain-2 siRNA. The present study found for the first time that miR-137 was downregulated in pulmonary arteries of hypoxic PH rats and in hypoxia-treated PASMCs. miR-137 mimic inhibited hypoxia-induced PASMC proliferation and upregulation of calpain-2 expression in PASMCs. Furthermore, miR-137 inhibitor induced the proliferation of PASMCs under normoxia, and knockdown of calpain-2 mRNA by siRNA significantly inhibited hypoxia-induced proliferation of PASMCs. Our study demonstrated that hypoxia-induced downregulation of miR-137 expression promoted the proliferation of PASMCs by targeting calpain-2, thereby potentially resulting in pulmonary vascular remodeling in hypoxic PH. [ABSTRACT FROM AUTHOR]

Aims Pulmonary hypertension (PH) is a proliferative disorder characterized by enhanced proliferation and suppressed apoptosis of intrapulmonary vascular smooth muscle cells. Recently, network-based bioinformatics have identified let-7 family, a tumor suppressive microRNA, regulate multiple interacting targets relevant to PH. However, the role of let-7 in vascular homeostasis in PH remains unknown. Thus, we wanted to investigate the role of let-7 in hypoxia-induced PASMCs proliferation and the underlying mechanism in hypoxic pulmonary hypertension (HPH). Main methods The male Sprague–Dawley (SD) rats were exposed to hypoxia (10% O 2 ) for 21 days to induce HPH. The expression of let-7 was determined by quantitative real-time polymerase chain reaction (qRT-PCR) and in situ hybridization. Primary rat PASMCs were exposed to hypoxia (3% O 2 ). MTS and EDU were performed to evaluate PASMCs proliferation. The mRNA and protein expression of c-myc, Bmi-1 and p16 were determined by qRT-PCR and Western blotting, respectively. The functions of let-7g on PASMCs proliferation, c-myc, Bmi-1 and p16 expression were assessed by let-7g mimic and inhibitor transfection. Key findings Among let-7 family members, only let-7b and let-7g were significantly down-regulated in remodeled pulmonary artery in HPH rats. Furthermore, only let-7g level was decreased in hypoxic PASMCs. Either hypoxia or let-7g inhibitor stimulated proliferation of PASMCs, let-7g mimic inhibited hypoxia-induced PASMCs proliferation. C-myc was the target of let-7g in PASMCs. Transfect of let-7g mimic inhibited hypoxia-induced c-myc, Bmi-1 up-regulation and p16 down-regulation, which ultimately controls cell cycle progression. Significance Loss of inhibition on c-myc-Bmi-1-p16 signaling pathway by let-7g may lead to PASMCs proliferation and vascular remodeling in HPH. [ABSTRACT FROM AUTHOR]

Pulmonary artery smooth muscle cells (PASMCs) phenotypic switching and pulmonary artery endothelial cells (PAECs) endothelial-mesenchymal transition (EndMT) are important in promoting pulmonary hypertension (PH)-pulmonary vascular remodeling (PVR). Resveratrol can efficiently inhibit the proliferation of PASMCs, but its application is limited due to its low bioavailability and solubility. In this study, we modified resveratrol to assess the role of A ring N(CH 3) 2 -based derivatives of resveratrol (Res4) in PVR-PASMCs phenotypic switching and PVR-PAECs EndMT. Chemical methods were used for the preparation of Res4; NMRS and HPLC were used to authenticate Res4. Mice developed PVR after 4 weeks of hypoxia (10% O 2). Res4 (50 mg/kg/d) attenuated right ventricular systolic pressure, right ventricular hypertrophy, and PVR. PASMCs developed phenotypic switching and PAECs developed EndMT after 2 days of hypoxia (3% O 2). Res4 (10 μM) could inhibit PASMCs and PAECs viability. Res4 could decrease proliferating cell nuclear antigen (PCNA) and osteopontin (OPN) expression, and increase α-smooth muscle actin (α-SMA) and vimentin expression in PASMCs. It could also decrease PCNA, α-SMA, vimentin expression and increase platelet endothelial cell adhesion molecule (CD31) expression in PAECs. Notably, Res4 inhibited the phosphorylation levels of mitogen-activated protein kinase kinase (MEK), extracellular signal-regulated protein kinase (ERK), Jun-N-terminal kinase (JNK), and p38 kinase in hypoxia-treated PASMCs and PAECs, indicating MAPK pathway may be involved in Res4-induced inhibition of PASMCs phenotypic switching and PAECs EndMT. Our data demonstrated that Res4 exerts antiproliferative effects by regulating PASMCs phenotypic switching and PAECs EndMT. Res4 may be potentially used as a drug against PH-PVR. [ABSTRACT FROM AUTHOR]