MCT-induced Pulmonary Arterial Hypertension Rats Research Articles

Stabilization of RyR2 maintains right ventricular function, reduces the development of ventricular arrhythmias, and improves prognosis in pulmonary hypertension.

Right ventricular (RV) dysfunction and its associated arrhythmias are recognized as important determinants of the prognosis of pulmonary arterial hypertension (PAH). Here, we aimed to investigate whether direct pharmacological intervention in the RV muscle with dantrolene (DAN), a stabilizer of the cardiac ryanodine receptor (RyR2), has a protective effect against RV dysfunction and arrhythmia in a monocrotaline (MCT)-induced PAH rat model. Male 8-week-old Sprague-Dawley rats were injected with MCT for the induction of PAH. Induction of ventricular tachycardia (VT) by catecholamines was also evaluated in association with RyR2-mediated Ca2+ release properties in isolated cardiomyocytes. A pulmonary artery-banding model has also been established to assess the independent effects of chronic pressure overload on RV morphology and function. In the MCT-induced PAH rat model, RV hypertrophy, dilation, and functional decline were observed, with a survival rate of 0% 2 months after MCT induction. In contrast, chronic DAN treatment improved all these RV parameters and increased survival by 80%. Chronic DAN treatment also prevented the dissociation of calmodulin from RyR2, thereby inhibiting Ca2+ sparks and spontaneous Ca2+ transients in MCT-induced hypertrophied RV cardiomyocytes. Epinephrine induced VT in more than 50% of rats with MCT-induced PAH, but complete suppression of VT was achieved by chronic DAN treatment. Stabilization of RyR2 by DAN has potential as a new therapeutic agent against the development of RV dysfunction and fatal arrhythmia associated with PAH.

PDZ‐Binding Kinase Drives Pulmonary Artery Smooth Muscle Proliferation and Vascular Remodeling in Pulmonary Arterial Hypertension

Pulmonary Arterial Hypertension (PAH) is a progressive disease that is caused by high blood pressure in the lungs that originates from increased resistance of small pulmonary arteries (PA). A defining characteristic of PAH is vascular smooth muscle cell (VSMC) proliferation and remodeling of PA, that eventually results in right ventricular failure and death. The hyperproliferative nature of vascular cells in PAH shares many characteristics with cancer cells such as sustained proliferative signaling, changes in hypoxia signaling and cellular metabolism. Using microarray analysis, we discovered a novel gene, PDZ‐Binding Kinase (PBK) that is upregulated in hypertensive PA. PBK is a serine/threonine kinase that has important roles in mitosis and cell proliferation. Also, elevated expression of PBK is associated with numerous aggressive cancers suggesting that it may be an important contributor to PAH. Our hypothesis is that PBK has a functional role in the pathogenesis of PAH but the therapeutic utility of targeting PBK in PAH and the mechanisms by which PBK promotes pulmonary vascular remodeling have not been studied. To investigate the role of PBK in PAH, we performed immunostaining, and found that PBK was highly upregulated in pulmonary arterial smooth muscle in the lungs of two experimental PAH rat models (MCT; Su/H), in the Su/H mouse model, as well as in human PAs and lungs with PAH. Furthermore, human pulmonary arterial smooth cells (HPASMCs) overexpressing PBK showed increased proliferation, while silencing PBK or in vitro pharmacological inhibition significantly reduced HPASMC proliferation. To determine whether PBK plays an important role in PA remodeling and PAH in vivo, we next utilized PBK inhibitor (OTS‐514) to treat MCT‐induced PAH rats in a reversal treatment method and Su/H Rats and Mouse in a preventative treatment. In all of the PAH animal models, right ventricle (RV) thickness, velocity time integral (VTI, index of PA stiffness), right ventricular systolic pressure (RVSP), and the Fulton Index were significantly improved in the presence of the PBK inhibitor. To complement our pharmacological studies with a genetic approach, we have generated PBK KO rats to investigate whether genetic ablation of PBK protects against the development of PAH. Taken together, these data support the hypothesis, that PBK drives pulmonary artery smooth muscle proliferation leading to abnormal vascular remodeling and the development of PAH. Our findings advance the utility of novel therapeutic approaches targeting PBK to improve the morbidity and mortality associated with PAH.

High-circulating gut microbiota-dependent metabolite trimethylamine N-oxide is associated with poor prognosis in pulmonary arterial hypertension.

AimsWe aimed to examine the hypothesis that circulating trimethylamine-N-oxide (TMAO) levels serve as a biomarker in pulmonary arterial hypertension (PAH), and to determine whether 3,3-dimethyl-1-butanol (DMB), a TMAO inhibitor, exerted a protective effect in monocrotaline (MCT)-induced PAH rats.Methods and resultsIn-patients with PAH were prospectively recruited from the Fuwai Hospital. Fasting blood samples were obtained to assess the TMAO levels and other laboratory values during the initial and second hospitalization. In a MCT-induced PAH rat, a normal diet and water supplemented with or without 1% DMB were administered for 4 weeks. The TMAO levels, haemodynamic examinations, changes in organ-tissue, and molecular levels were evaluated. In total, 124 patients with PAH were enrolled in this study. High TMAO levels were correlated with increased disease severity and poor prognosis even after adjusting for confounders. The TMAO levels in the rats decreased in the MCT + DMB group, accompanied by improved haemodynamic parameters, decreased right ventricular hypertrophy, and amelioration of pulmonary vascular remodelling. The decrease in abnormal apoptosis, excessive cell proliferation, transforming growth factor-β expression, and restoration of endothelial nitric oxide synthase after DMB treatment further explained the amelioration of PAH.ConclusionIncreased TMAO levels were associated with poor prognosis in patients with PAH, and DMB played a protective effect in MCT-induced PAH rat.

The zinc transporter ZIP12 regulates monocrotaline-induced proliferation and migration of pulmonary arterial smooth muscle cells via the AKT/ERK signaling pathways

BackgroundThe zinc transporter ZIP12 is a membrane-spanning protein that transports zinc ions into the cytoplasm from the extracellular space. Recent studies demonstrated that upregulation of ZIP12 is involved in elevation of cytosolic free zinc and excessive proliferation of pulmonary arterial smooth muscle cells (PASMCs) induced by hypoxia. However, the expression of ZIP12 and its role in pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT) in rats have not been evaluated previously. The aim of this study was to investigate the effect of ZIP12 on the proliferation and migration of PASMCs and its underlying mechanisms in MCT-induced PAH.MethodsA PAH rat model was generated by intraperitoneal injection of 20 mg/kg MCT twice at one-week intervals. PASMCs were isolated from the pulmonary arteries of rats with MCT-induced PAH or control rats. The expression of ZIP12 and related molecules was detected in the lung tissues and cells. A ZIP12 knockdown lentivirus and an overexpressing lentivirus were constructed and transfected into PASMCs derived from PAH and control rats, respectively. EdU assays, wound healing assays and Western blotting were carried out to explore the function of ZIP12 in PASMCs.ResultsIncreased ZIP12 expression was observed in PASMCs derived from MCT-induced PAH rats. The proliferation and migration of PASMCs from PAH rats were significantly increased compared with those from control rats. These results were corroborated by Western blot analysis of PCNA and cyclin D1. All these effects were significantly reversed by silencing ZIP12. Comparatively, ZIP12 overexpression resulted in the opposite effects as shown in PASMCs from control rats. Furthermore, selective inhibition of AKT phosphorylation by LY294002 abolished the effect of ZIP12 overexpression on enhancing cell proliferation and migration and partially suppressed the increase in ERK1/2 phosphorylation induced by ZIP12 overexpression. However, inhibition of ERK activity by U0126 resulted in partial reversal of this effect and did not influence an increase in AKT phosphorylation induced by ZIP12 overexpression.ConclusionsZIP12 is involved in MCT-induced pulmonary vascular remodeling and enhances the proliferation and migration of PASMCs. The mechanism of these effects was partially mediated by enhancing the AKT/ERK signaling pathways.

Metabotropic glutamate receptor 5 blockade attenuates pathological cardiac remodelling in pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is characterized by cardiac remodelling. Glutaminolysis plays a crucial role in PAH-induced remodelling. The metabotropic glutamate receptor 5(mGluR5) may mediate this process. This study investigated whether or not the blockade of mGluR5may attenuate PAH-induced pathological cardiac remodelling. Pulmonary arterial hypertension was induced by intraperitoneally injecting male Sprague-Dawley (SD) rats with 60mg/kg of monocrotaline (MCT). 3-((2-Methyl-4-thiazolyl)ethynyl)pyridine (MTEP) (10 mg/kg intraperitoneally) was used as a therapeutic intervention to block mGluR5. Cardiac functions were assessed with right heart catheterization and electrocardiography. Alterations in protein expressions and inflammatory markers were investigated using western blot and enzyme-linked immunosorbent assay (ELISA), respectively. Increased right ventricular systolic pressure (RSVP), elevated protein expressions of mGluR5, collagen types I and III and cartilage intermediate layer protein 1 (CILP1), enhanced phosphorylation of phosphatidylinositol 3-kinase (PI3K), AKT and p38 mitogen-activated protein kinase (P38MAPK), increased angiopoietin 2 (Ang 2) and vascular endothelial growth factor-α (VEGF) protein expressions and elevated serum levels of interleukin 6 (IL-6) and tumour necrotic factor α (TNF-α) were observed in MCT-induced PAH rats. MTEP improved hemodynamics and right ventricular hypertrophy. MTEP also attenuated MCT-induced elevations in the protein expressions of mGluR5, collagen types I and III, CILP1, Ang 2 and VEGF and decreased PI3K, AKT and P38MAPK phosphorylations and inflammatory cytokine levels. Metabotropic glutamate receptor 5 blockade using MTEP ameliorates PAH-induced pathological right cardiac remodelling via inhibiting the signalling cascade involving PI3K/AKT, P38MAPK, Ang 2 and VEGF.

The therapeutic effect and mechanism of Rapamycin combined with HO-3867 on monocrotaline-induced pulmonary hypertension in rats

This study test was designed to investigate the possible modulatory effect of rapamycin combined with HO-3867 in monocrotaline(MCT)-induced pulmonary arterial hypertension in rats. We hypothesized that combined treatment with rapamycin and HO-3867 is superior to either alone in attenuating MCT-induced rat pulmonary arterial hypertension (PAH). Pulmonary arterial hypertension was induced by a single intraperitoneal injection of monocrotaline (60 mg/kg). 2 weeks later, rapamycin (2 mg/kg i.p.) and HO3867 (10 mg/kg i.h.) were administered daily, alone and in combination, for 2 weeks. Right ventricular systolic pressure, echocardiography were recorded and then rats were sacrificed. Histological analysis of pulmonary arteries medial wall thickness, right ventricular hypertrophy index (RVHI), the ratio of right ventricular to body weight, and collagen volume fraction (CVF) of right ventricular were performed. Moreover, the expression of t-STAT3, p-STAT3, t-Akt, p-Akt in lung and t-STAT3, p-STAT3, t-S6, p-S6 in right ventricular were examined. The result showed that combined treatment provided a considerable improvement toward maintaining hemodynamic changes, lung vascular remodeling as well as amending RV remodeling and function. Furthermore, Combined treatment can normalize the protein levels of two signal pathways in lung and heart tissue, where p-S6 or p-Akt significantly decreased compared to HO-3867 alone, or p-STAT3 significantly reduced compared to rapamycin alone. In conclusion, combined treatment with rapamycin and HO-3867 is superior to either alone in attenuating MCT-induced PAH in rats.

Effects of Crocin on CCL2/CCR2 Inflammatory Pathway in Monocrotaline-Induced Pulmonary Arterial Hypertension Rats.

Pulmonary arterial hypertension (PAH) is a malignant cardiopulmonary disease, in which pulmonary arterial remodeling is regarded as the prominent pathological feature. So far, the mechanism of PAH is still unclear, so its treatment remains a challenge. However, inflammation plays an important part in the occurrence and progression of PAH. It is well known that crocin has anti-inflammatory properties, so we investigated whether crocin could be a potential drug for the treatment of PAH rat models. Rats injected subcutaneously with monocrotaline (MCT) were treated with crocin via a gastric tube daily for four weeks. The results showed that crocin treatment significantly reduced the right ventricular systolic pressure (RVSP) and mean pulmonary artery pressure (mPAP) in the PAH rat models. Moreover, crocin treatment reduced the proliferation of pulmonary arteriole smooth muscle cells (PASMCs). In addition, crocin treatment not only relieved inflammatory cell infiltration and collagen fiber hyperplasia in the lung and right ventricle, but also decreased the expression of the CCL2/CCR2 inflammatory pathway in the lung of PAH rat models. Furthermore, crocin treatment reduced the inflammatory cytokines and oxidative stress responses. In summary, crocin may play a protective role in MCT-induced PAH rats by alleviating inflammatory response, improving pulmonary arterial remodeling, and preventing PAH. Therefore, crocin as a new treatment for PAH may be quite worthy of consideration.

Inhibition of HDAC1 alleviates monocrotaline-induced pulmonary arterial remodeling through up-regulation of miR-34a

BackgroundIt has been found that up-regulation of histone deacetylases 1 (HDAC1) is involved in the development of pulmonary arterial hypertension (PAH). However, it is still unclear whether inhibition of HDAC1 suppresses the development of PAH via restoring miR-34a level in monocrotaline (MCT)-induced PAH rats.MethodsPAH rat models were induced by intraperitoneal injection of MCT. HDAC1 was suppressed by intraperitoneal injection of the class I HDAC inhibitor MS-275, and miR-34a was over-expressed via tail vein injection of miR-34a agomiR.ResultsHDAC1 protein was significantly increased in MCT-induced PAH rats; this was accompanied with down-regulation of miR-34a and subsequent up-regulation of matrix metalloproteinase 9 (MMP-9)/tissue inhibitor of metalloproteinase 1 (TIMP-1) and MMP-2/TIMP-2. Administration of PAH rats with MS-275 or miR-34a agomiR dramatically abolished MCT-induced reduction of miR-34a and subsequent up-regulation of MMP-9/TIMP-1 and MMP-2/TIMP-2, finally reduced extracellular matrix (ECM) accumulation, pulmonary arterial remodeling, right ventricular systolic pressure (RVSP) and right ventricle hypertrophy index (RVHI) in PAH rats.ConclusionsHDAC1 contributes to the development of MCT-induced rat PAH by suppressing miR-34a level and subsequently up-regulating the ratio of MMP-9/TIMP-1 and MMP-2/TIMP-2. Inhibition of HDAC1 alleviates pulmonary arterial remodeling and PAH through up-regulation of miR-34a level and subsequent reduction of MMP-9/TIMP-1 and MMP-2/TIMP-2, suggesting that inhibition of HDAC1 might have potential value in the management of PAH.

GOLPH3 Contributes to Endothelial Cells Pyroptosis by Promoting Golgi Dispersal in Pulmonary Arterial Hypertension

Background: Increased release of inflammatory cytokines caused by NLRP3 inflammasome activation-dependent endothelial cells pyroptosis is involved in the progression of pulmonary arterial hypertension (PAH). Disassembly of the trans-Golgi network (TGN) results in NLRP3 oligomerization and inflammasome activation, and Golgi structural proteins are the key factors to maintain Golgi homeostasis. We attempted to demonstrate the impact of Golgi structural proteins on activation of NLRP3 inflammasome and endothelial cells pyroptosis under pro-pulmonary hypertensive condition. Methods: Lung homogenates isolated from MCT-induced PAH rats and TNF-α-induced pulmonary artery endothelial cells (PAECs) lysates were obtained to access mRNA levels of Golgi matrix proteins by real-time PCR. Silence or overexpression approaches were used to determine potential involvement of selected Golgi matrix protein in regulating NLRP3 inflammasome activation. We utilized confocal scanning and co-immunoprecipitation to confirm interaction of TGN and NLRP3. To determine PAECs pyroptosis, we used western blot, LDH release, flow cytometry assay and Hoechst/PI double staining analysis. Findings: We found up-regulated GOLPH3 in PAH rats and TNF-α-induced PAECs. Silencing GOLPH3 in PAECs repressed TNF-α-induced NLRP3 inflammasome activation, then ameliorated GSDMD-mediated PAECs pyroptosis. And GOLPH3 enhanced dispersed TGN and its interaction with NLRP3 inflammasome. Interpretation: Our findings revealed that up-regulated GOLPH3 contributes to NLRP3 inflammasome activation thus causing PAECs pyroptosis through promoting Golgi dispersal in PAH, which indicate a novel pathophysiology mechanism and therapeutic target for PAH. Funding Information: This study was supported in part by the National Natural Science Foundation of China Projects 81930012 and 81730013, and Hunan Provincial Natural Science Foundation project 2019JJ50908. Declaration of Interests: There is no conflict of interest in this manuscript. Ethics Approval Statement: All animal protocols are based on the experimental animal welfare ethics guide drawn up by the Chinese Society of Laboratory Animals. This study was approved by the Animal Experimental Center of Central South University and the Animal Experimental Center of Hunan Normal University.

Ligustrazine Suppresses Platelet-Derived Growth Factor-BB-Induced Pulmonary Artery Smooth Muscle Cell Proliferation and Inflammation by Regulating the PI3K/AKT Signaling Pathway.

Pulmonary arterial hypertension (PAH) is a serious pulmonary vascular disease. Excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) plays an important role in the course of this disease. Ligustrazine is an alkaloid monomer extracted from the rhizome of the herb Ligusticum chuanxiong. It is often used to treat cardiovascular diseases, but its effect on PAH has rarely been reported. This study aims to explore the protective effect and mechanism of ligustrazine on PAH. In the in vivo experiment, monocrotaline (MCT) was used to induce PAH in rats, and then ligustrazine (40, 80, 160 mg/kg/day) or sildenafil (25 mg/kg/day) was administered. Four weeks later, hemodynamic changes, right ventricular hypertrophy index, lung morphological characteristics, inflammatory factors, phosphoinositide 3-kinase (PI3K), and AKT expression were evaluated. In addition, primary rat PASMCs were extracted by the tissue adhesion method, a proliferation model was established with platelet-derived growth factor-BB (PDGF-BB), and the cells were treated with ligustrazine to investigate its effects on cell proliferation, inflammation, and cell cycle distribution. The results indicate that ligustrazine can markedly alleviate right ventricular systolic pressure, right ventricular hypertrophy, pulmonary vascular remodeling, and inflammation caused by MCT, and that it decreased PI3K and AKT phosphorylation expression. Moreover, ligustrazine can inhibit the proliferation and inflammation of PASMCs and arrest the progression of G0/G1 to S phase through the PI3K/AKT signaling pathway. Therefore, we conclude that ligustrazine may inhibit the proliferation and inflammation of PASMCs by regulating the activation of the PI3K/AKT signaling pathway, thereby attenuating MCT-induced PAH in rats. Collectively, these findings suggest that ligustrazine may be a promising therapeutic for PAH.

BKCa Channel Activation Attenuates the Pathophysiological Progression of Monocrotaline-Induced Pulmonary Arterial Hypertension in Wistar Rats.

In the present study, the therapeutic efficacy of a selective BKCa channel opener (compound X) in the treatment of monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) was investigated. PAH was induced in male Wistar rats by a single injection of MCT. After two weeks, the MCT-treated group was divided into two groups that were either treated with compound X or vehicle. Compound X was administered daily at 28mg/kg. Electrocardiographic, echocardiographic, and haemodynamic analyses were performed; ex vivo evaluations of pulmonary artery reactivity, right ventricle (RV) and lung histology as well as expression levels of α and β myosin heavy chain, brain natriuretic peptide, and cytokines (TNFα and IL10) in heart tissue were performed. Pulmonary artery rings of the PAH group showed a lower vasodilatation response to acetylcholine, suggesting endothelial dysfunction. Compound X promoted strong vasodilation in pulmonary artery rings of both control and MCT-induced PAH rats. The untreated hypertensive rats presented remodelling of pulmonary arterioles associated with increased resistance to pulmonary flow; increased systolic pressure, hypertrophy and fibrosis of the RV; prolongation of the QT and Tpeak-Tend intervals (evaluated during electrocardiogram); increased lung and liver weights; and autonomic imbalance with predominance of sympathetic activity. On the other hand, treatment with compound X reduced pulmonary vascular remodelling, pulmonary flow resistance and RV hypertrophy and afterload. The use of a selective and potent opener to activate the BKCa channels promoted improvement of haemodynamic parameters and consequent prevention of RV maladaptive remodelling in rats with MCT-induced PAH.

Abstract 13715: Pathophysiological Role of Dexmedetomidine for Monocrotaline-induced Pulmonary Arterial Hypertension in Rats

Introduction: The abnormal proliferation of pulmonary arterial smooth muscle cells (PASMCs) is one of pathological characteristics of pulmonary arterial hypertension (PAH). Inflammation is thought to play an important role for PASMCs proliferation in PAH. Dexmedetomidine (DEX) is a selective α2-adrenergic receptor agonist that is used as a sedative in clinical settings. It has been reported that DEX regulates certain inflammatory responses. Hypothesis: DEX ameliorates Monocrotaline (MCT)-induced PAH in rats through its anti-inflammatory effect. Methods: In vivo, 6-week-old male Sprague-Dawley rats were injected 60 mg/kg of MCT subcutaneously. At day 14 after MCT injection, continuous infusions of DEX (2μg/kg/hour) by osmotic pumps were started in one group (MCT + DEX group), and not in another group (MCT group). We performed cardiac catheterization to measure right ventricular systolic pressure (RVSP) and prepared rats paraffin embedded lung tissues for Immunohistochemistry at day 23. In vitro, we analyzed the effect of DEX on human PASMCs (hPASMCs) proliferation stimulated with fibroblast growth factor 2 (FGF2). In addition, we examined mRNA levels of proinflammatory cytokines in hPASMCs by FGF2 stimuation with/without DEX. Results: Both RVSP and survival rate markedly improved in MCT + DEX group compared with those in MCT group (RVSP; 34mmHg ± 4mmHg vs. 70mmHg ± 10mmHg, survival rate 42% vs. 0% at day 29). In histological analysis, medial hypertrophy of pulmonary arterioles and phosphorylated-p65 positive PASMCs significantly reduced in MCT + DEX group. DEX also inhibited hPASMCs proliferation dose dependently. Furthermore, IL-6 mRNA expression was suppressed by DEX in hPASMCs stimulated with FGF2. Conclusions: DEX improved MCT-induced PAH in rats by suppressing PASMCs proliferation through the anti-inflammatory effect, which may result from inhibition of NF-κB activation induced by IL-6. DEX can be a new therapeutic tool for PAH.

Abstract 12535: MicroRNA-663 Ameliorates Monocrotaline-induced Pulmonary Arterial Hypertension by Targeting TGFβ1/smad2/3 Signaling

Objective: Pulmonary vascular remodeling due to excessive growth factor production and pulmonary artery smooth muscle cells (PASMCs) proliferation is the hallmark feature of pulmonary arterial hypertension (PAH). Recent studies suggest that miR-663 is a potent modulator for tumorigenesis and atherosclerosis. However, whether miR-663 involves in pulmonary vascular remodeling is still unclear. Methods and Results: By using quantitative RT-PCR, we found that miR-663 was highly expressed in normal human PASMCs. In contrast, circulating level of miR-663 dramatically reduced in PAH patients. In addition, in situ hybridization showed that expression of miR-663 was decreased in PAMSCs of PAH patients. Furthermore, MTT and cell scratch-wound assay showed that transfection of miR-663 mimics significantly inhibited platelet derived growth factor (PDGF)-induced PASMC proliferation and migration, while knockdown of miR-663 expression enhanced these effects. Mechanistically, dual-luciferase reporter assay revealed that miR-663 directly targets the 3’UTR of TGF-β1. Moreover, western blots and ELISA results showed that miR-663 decreased PDGF-induced TGF-β1 expression and secretion, which in turn suppressed the downstream smad2/3 phosphorylation and collagen I expression. Finally, intratracheal instillation of adeno-miR-663 dramatically attenuated pulmonary vascular remodeling and right ventricular hypertrophy, as well as right ventricular systolic pressure and mean pulmonary arterial pressure in MCT-induced PAH rat models. Conclusion: These results indicate that miR-663 is a potential biomarker for PAH. MiR-663 decreases PDGF-BB-induced PAMSCs proliferation and ameliorates pulmonary vascular remodeling and right ventricular hypertrophy in MCT-PAH by targeting TGF-β1/smad2/3 signaling. These findings suggest that miR-663 may represent as an attractive approach for the diagnosis and treatment of PAH.

Protective effects of isorhamnetin on pulmonary arterial hypertension: in vivo and in vitro studies.

Pulmonary arterial hypertension (PAH) is a malignant disease with high mortality and closely involves the bone morphogenetic protein (BMP) pathway. Mutations in BMPR2 caused proliferation of pulmonary artery smooth muscle cells (PASMCs) leading to PAH. Isorhamnetin, one of the main naturally occurring flavonoids extracted from Hippophae rhamnoides L, shows antiinflammatory and anti-proliferative properties. Nevertheless, the effects of isorhamnetin on PAH remain unclear. This study aimed to investigate whether isorhamnetin has protective effects against PAH and explore possible mechanisms. An in vivo model of PAH induced by monocrotaline (MCT) was employed, and sildenafil and isorhamnetin were orally administered for 21 consecutive days. An in vitro model induced by TNF-α was employed, and cell proliferation of HPASMCs was detected. Results indicated that isorhamnetin significantly improved hemodynamic, histopathological, and echocardiographic changes in MCT-induced PAH in rats. In vitro, isorhamnetin suppressed TNF-α-induced HPASMCs proliferation. Furthermore, isorhamnetin improved protein expression of BMPR2 and suppressed protein expression of TNF-α and IL-6 in rat lungs. Isorhamnetin improved protein expression of BMPR2 and p-smad1/5 and mRNA expression of Id1 and Id3 in HPASMCs. Isorhamnetin ameliorated MCT-induced PAH in rats and inhibited TNF-α-induced HPASMCs proliferation by a mechanism likely involving the regulation of the BMP signaling pathway.

Early Intervention of Tongxinluo () on Right Ventricular Function Assessed by Echocardiography in Rats with Pulmonary Arterial Hypertension Induced by Monocrotaline.

To investigate the effect of early intervention of Tongxinluo (, TXL) on right ventricular function (RVF) of rats with pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT). A total of 30 adult male Sprague-Dawley rats were assigned to 5 groups with complete random experiment design: Sham group (Sham), MCT group, TXL group, sildenafil (SIL) group and combination group (TXL+SIL), 6 rats in each group. Rats were injected with 50 mg/kg MCT solution for inducing PAH model except for those in the sham group. From the day of modeling, rats of TXL, SIL and TXL+SIL groups were given TXL (1.2 g/kg), SIL (10 mg/kg) and combination solution (TXL:1.2 g/kg, SIL: 10 mg/kg) respectively, and rats in Sham and MCT groups were given normal saline (5 mL/kg). The samples were collected and tested after 21 consecutive days of intragastric administration. Echocardiography was used to measure the related indices of RVF, including pulmonary arterial flow spectrum, pulmonary artery diameter (PAD), right ventricular wall thickness (RVWT), right ventricular diameter (RVD), tricuspidannular plane systolic excursion (TAPSE), right atrium transverse diameter (RAT), and inferior vena cava diameter (IVCD). Elastic Verhoeff-Van Gieson staining was adopted to measure the percentage of wall thickness (WT%) of pulmonary arteriols. Hematoxylin-eosin staining was used to measure the cross-sectional area (CSA) of right ventricular cardiomyocytes. MCT-induced PAH rat model was successfully established. In MCT group the wall of pulmonary arterioles exhibited a prominent-increase thickness, PAD, RVWT, RVD, RAT, IVCD, WT%, right ventricular hypertrophy index (RVHI) as well as CSA of RV cardiomyocyte significantly increased (all P<0.01), and TAPSE markedly decreased (P<0.01). At the same time, TXL prominently improved all of the above indices (all P<0.01). In comparison with SIL, TXL significantly reduced RVD (P<0.05) and decreased CAS of RV cardiomyocytes (P<0.01), but TAPSE in SIL group was much larger than in TXL group (P<0.01). Moreover, TAPSE in TXL+SIL group was larger than that in TXL group (P<0.01), while the two groups performed equally well in terms of the other indices. Early intervention of TXL could inhibit pulmonary arterioles remodeling, and improve RVF by attenuating right ventricular hypertrophy, and TXL has a stronger effect on inhibiting right ventricular remodeling than SIL.

MiR-182-3p/Myadm contribute to pulmonary artery hypertension vascular remodeling via a KLF4/p21-dependent mechanism.

Rationale: There is a continued need for investigating the roles of microRNAs and their targets on the pathogenesis of pulmonary arterial hypertension (PAH) vascular remodeling. We recently identified the association of myeloid miR-182-3p and its new target, Myeloid-Associated Differentiation Marker (Myadm), with vascular remodeling. Here, we aimed to determine the role of miR-182-3p/Myadm on PAH vascular remodeling and the underlying molecular mechanism.Methods: The miR-182-3p/Myadm expression profiles were detected in PAH patients and experimental rodent models. Loss-of-function and gain-of-function studies using gene knock-in or gene knock-out and the combinations of the proteomic technology and genome-wide ChIP-Seq were employed to determine the downstream targets of miR-182-3p/Myadm in response to monocrotaline (MCT)-induced PAH.Results: The miR-182-3p/Myadm expression was altered in PAH patients and experimental rodent models. Both miR-182-3p inhibitor and overexpression of Myadm augmented the pathological progression in rats in response to MCT-induced PAH. In contrast, miR-182-3p mimic and Myadm gene knockout attenuated the changes in the hemodynamics and structure of the cardio-pulmonary system in MCT-induced PAH in rats. Myadm mediated the proliferation of pulmonary artery smooth muscle cells (PASMCs) by altering the cell cycle kinase inhibitor (p21/Cip1) expression through the transcription factor Krüppel-like factor 4 (KLF4) translocation into the cytoplasm.Conclusion: Our findings indicate the prognostic and therapeutic significance of miR-182-3p in PAH and provide a new regulatory model of the myeloid-derived miR-182-3p/Myadm/KLF4/p21 axis in PAH vascular remodeling.

Preventive treatment with ginsenoside Rb1 ameliorates monocrotaline-induced pulmonary arterial hypertension in rats and involves store-operated calcium entry inhibition

Context Ginsenoside Rb1, the main active ingredient of ginseng, exhibits ex vivo depression of store-operated calcium entry (SOCE) and related vasoconstriction in pulmonary arteries derived from pulmonary hypertension (PH) rats. However, the in vivo effects of ginsenoside Rb1 on PH remain unclear. Objective This study explored the possibility of using ginsenoside Rb1 as an in vivo preventive medication for type I PH, i.e., pulmonary arterial hypertension (PAH), and potential mechanisms involving SOCE. Materials and methods Male Sprague-Dawley rats (170–180 g) were randomly divided into Control, MCT, and MCT + Rb1 groups (n = 20). Control rats received only saline injection. Rats in the MCT + Rb1 and MCT groups were intraperitoneally administered single doses of 50 mg/kg monocrotaline (MCT) combined with 30 mg/kg/day ginsenoside Rb1 or equivalent volumes of saline for 21 consecutive days. Subsequently, comprehensive parameters related to SOCE, vascular tone, histological changes and hemodynamics were measured. Results Ginsenoside Rb1 reduced MCT-induced STIM1, TRPC1, and TRPC4 expression by 35.00, 31.96, and 32.24%, respectively, at the protein level. SOCE-related calcium entry and pulmonary artery contraction decreased by 162.6 nM and 71.72%. The mean pulmonary artery pressure, right ventricle systolic pressure, and right ventricular mass index decreased by 19.5 mmHg, 21.6 mmHg, and 39.50%. The wall thickness/radius ratios decreased by 14.67 and 17.65%, and the lumen area/total area ratios increased by 18.55 and 15.60% in intrapulmonary vessels with 51–100 and 101–150 μm o.d. Conclusion Ginsenoside Rb1, a promising candidate for PH prevention, inhibited SOCE and related pulmonary vasoconstriction, and relieved MCT-induced PAH in rats.

Inhibition of Siah2 ubiquitin ligase ameliorates monocrotaline-induced pulmonary arterial remodeling through inactivation of YAP

AimsIt has been shown that up-regulation of E3 ubiquitin ligase seven-in-absentia-homolog 2 (Siah2) and activation of Hippo signaling pathway effector yes-associated protein (YAP) are involved in the development of pulmonary arterial hypertension (PAH). However, it is still unclear whether Siah2 activates YAP in monocrotaline (MCT)-induced PAH rat models. Main methodsIntraperitoneal injection of MCT was used to induce PAH rat models. The right ventricular systolic pressure (RVSP), right ventricle hypertrophy index (RVHI), percentage of medial wall thickness (%MT), α-SMA, Ki-67 and TUNEL staining were performed to evaluate the development of PAH. Protein levels of Siah2, Lats1/2, YAP phosphorylation and total YAP, and the subcellular localization of YAP were examined using immunoblotting. Proteasome activity was measured by an assay kit. Key findingsThe protein level of Siah2 was significantly increased in MCT-induced PAH rats, this was accompanied with the proteasome-dependent degradation of Lats1/2 and subsequent up-regulation and dephosphorylation of YAP and its nuclear localization. Administration of PAH rats with Siah2 inhibitor Vitamin K3 or proteasome inhibitor MG-132 dramatically suppressed MCT-induced down-regulation of Lats1/2 and activation of YAP, finally reduced RVSP, RVHI, %MT, pulmonary arterial muscularization, pulmonary arterial smooth muscle cells (PASMCs) proliferation and enhanced PASMCs apoptosis in PAH rats. SignificanceSiah2 contributes to the development of MCT-induced PAH by destabilizing Lats1/2 and subsequently stimulating YAP activation. Inhibition of Siah2 or proteasome alleviates pulmonary arterial remodeling through inactivation of YAP, indicating Siah2 ubiquitin ligase as a novel target might have potential value in the management of PAH.

MiR-181b-5p inhibits endothelial-mesenchymal transition in monocrotaline-induced pulmonary arterial hypertension by targeting endocan and TGFBR1

Endothelial-mesenchymal transition (EndMT) is a frequent event in endothelial dysfunction, which is associated with pulmonary arterial hypertension (PAH). MiR-181 family members exert diverse effects in multiple biological processes. However, the relationships between miR-181b-5p (miR-181b) and EndMT in PAH are not well understood. In this study, Sprague-Dawley (SD) rats were injected with monocrotaline (MCT) to establish PAH model, and primary rat pulmonary arterial endothelial cells (rPAECs) were treated with TNF-α, TGFβ1 and IL-1β in combination to induce EndMT (I-EndMT). Then we explored miR-181b expression and examined its functional role in PAH. Our data showed that miR-181b was down-expressed in PAH, and its overexpression attenuated the hemodynamics, pulmonary vascular hypertrophy, right ventricular remodeling and EndMT process in MCT-induced PAH rats. In I-EndMT rPAECs, we observed that inducing miR-181b reversed the decrease of endothelial markers and increase of mesenchymal markers. However, knockdown of miR-181b induced similar effects to EndMT. In addition, endocan and TGFBR1 levels were also increased in EndMT, which were negatively regulated by miR-181b. Luciferase activity results indicated that endocan and TGFBR1 were direct target genes of miR-181b. In summary, our findings firstly demonstrate that the beneficial effect of miR-181b on PAH may be associated with endocan/TGFBR1-mediated EndMT, providing a new insight into the diagnosis and treatment of PAH.

RBMSC/Cav-1F92A Mediates Oxidative Stress in PAH Rat by Regulating SelW/14-3-3η and CA1/Kininogen Signal Transduction.

Background/Objectives Carbonic anhydrase 1 (CA1)/kininogen and selenoprotein W (SelW)/14-3-3η signal transduction orchestrate oxidative stress, which can also be regulated by nitric oxide (NO). The mutated caveolin-1 (Cav-1F92A) gene may enhance NO production. This study explored the effect of Cav-1F92A-modified rat bone marrow mesenchymal stem cells (rBMSC/Cav-1F92A) on oxidative stress regulation through CA1/kininogen and SelW/14-3-3η signal transduction in a rat model of monocrotaline- (MCT-) induced pulmonary arterial hypertension (PAH). Method PAH was induced in rats through the subcutaneous injection of MCT. Next, rBMSC/Vector (negative control), rBMSC/Cav-1, rBMSC/Cav-1F92A, or rBMSC/Cav-1F92A+L-NAME were administered to the rats. Changes in pulmonary hemodynamic and vascular morphometry and oxidative stress levels were evaluated. CA1/kininogen and SelW/14-3-3η signal transduction, endothelial nitric oxide synthase (eNOS) dimerization, and eNOS/NO/sGC/cGMP pathway changes were determined through real-time polymerase chain reaction, Western blot, or immunohistochemical analyses. Results In MCT-induced PAH rats, rBMSC/Cav-1F92A treatment reduced right ventricular systolic pressure, vascular stenosis, and oxidative stress; downregulated CA1/kininogen signal transduction; upregulated SelW/14-3-3η signal transduction; and reactivated the NO pathway. Conclusions In a rat model of MCT-induced PAH, rBMSC/Cav-1F92A reduced oxidative stress by regulating CA1/kininogen and SelW/14-3-3η signal transduction.