Role In Pulmonary Hypertension Research Articles

Endonuclear Circ-calm4 regulates ferroptosis via a circR-Loop of the COMP gene in pulmonary artery smooth muscle cells

Pulmonary hypertension (PH) is a serious pulmonary vascular disease characterized by vascular remodeling. Circular RNAs (CircRNAs) play important roles in pulmonary hypertension, but the mechanism of PH is not fully understood, particularly the roles of circRNAs located in the nucleus. Circ-calmodulin 4 (circ-calm4) is expressed in both the cytoplasm and the nucleus of pulmonary arterial smooth muscle cells (PASMCs). This study aimed to investigate the role of endonuclear circ-calm4 in PH and elucidate its underlying signaling pathway in ferroptosis. Immunoblotting, quantitative real-time polymerase chain reaction (PCR), malondialdehyde (MDA) assay, immunofluorescence, iron assay, dot blot, and chromatin immunoprecipitation (ChIP) were performed to investigate the role of endonuclear circ-calm4 in PASMC ferroptosis. Increased endonuclear circ-calm4 facilitated ferroptosis in PASMCs under hypoxic conditions. We further identified the cartilage oligomeric matrix protein (COMP) as a downstream effector of circ-calm4 that contributed to the occurrence of hypoxia-induced ferroptosis in PASMCs. Importantly, we confirmed that endonuclear circ-calm4 formed circR-loops with the promoter region of the COMP gene and negatively regulated its expression. Inhibition of COMP restored the phenotypes related to ferroptosis under hypoxia stimulation combined with antisense oligonucleotide (ASO)-circ-calm4 treatment. We conclude that the circ-calm4/COMP axis contributed to hypoxia-induced ferroptosis in PASMCs and that circ-calm4 formed circR-loops with the COMP promoter in the nucleus and negatively regulated its expression. The circ-calm4/COMP axis may be useful for the design of therapeutic strategies for protecting cellular functionality against ferroptosis and pulmonary hypertension.

Alveolar hypoxia induces organ-specific inflammasome-related inflammation in male mouse lungs.

Inflammation through activation of caspase-1, seems to play a role in pulmonary hypertension induced by alveolar hypoxia. Whether alveolar hypoxia induces caspase-1-mediated inflammation and influx of leukocytes in other organs than the lungs, is not known. Our aim was to explore sites of caspase-1-related inflammation in alveolar hypoxia. Wild type (WT) mice were exposed to environmental hypoxia or room-air, and organs were analyzed. Right heart catheterization was performed after 14 days of alveolar hypoxia in WT mice and mice transplanted with WT or caspase-1-/- bone marrow. Hypoxia induced leukocyte accumulation and increased caspase-1 protein in the lungs, not in other organs. WT mice transplanted with WT or caspase-1-/- bone marrow showed no difference in pulmonary leukocyte accumulation or development of pulmonary hypertension after alveolar hypoxia. Caspase-1 and IL-18 were detected in bronchial epithelium in WT mice, and hypoxia induced IL-18 secretion from bronchial epithelial cells. IL-18 stimulation generated IL-6 mRNA in monocytes. Phosphorylated STAT3 was increased in hypoxic lungs, not in other organs. Alveolar hypoxia induces caspase-1 activation and leukocyte accumulation specific to the lungs, not in other organs. Caspase-1 activation and IL-18 secretion from bronchial epithelial cells might initiate hypoxia-induced inflammation, leading to pulmonary hypertension.

MiR-210-5p Promotes Pulmonary Hypertension by Blocking ATP2A2.

Aberrant expression of ATPase sarcoplasmic/endoplasmic retic Ca2+ transporting 2 (ATP2A2) has attracted attention for its pathophysiologic role in pulmonary hypertension (PH). Several miRNAs, including miR-210-5p, have also been reported to be pathogenic factors in PH, but their exact mechanisms remain unknown. This study aimed to elucidate the potential mechanisms of miR-210-5p and ATP2A2 in MCT-induced PH. Eighteen Sprague-Dawley rats were randomly divided into two groups-monoclonal (MCT) group and control group-and then administered MCT (60mg/kg) and saline, respectively. mPAP, PVR, RVHI, WT%, and WA% were significantly increased in PH rats after 3weeks, confirming that the modeling of PH rats was successful. Subsequently, we determined the expression of ATP2A2 and miR-210-5p in lung tissues using WB and qRT-PCR methods. We established an in vitro model using BMP4 and TGF-β1 treatment of pulmonary artery smooth muscle cells (PASMCs) and examined the expression of ATP2A2 and miR-210-5p using the same method. To further elucidate the regulatory relationship between ATP2A2 and miR-210-5p, we altered the expression level of miR-210-5p and detected the corresponding changes in ATP2A2 levels. In addition, we demonstrated the relationship by dual luciferase experiments. Finally, the effect of silencing ATP2A2 could be confirmed by the level of cell membrane Ca2+ in PAMSCs. Up-regulation of miR-210-5p and down-regulation of ATP2A2 were observed in the MCT group compared with the control group, which was confirmed in the in vitro model. In addition, elevated miR-210-5p expression decreased the level of ATP2A2 while increasing the proliferation of PASMCs, and the results of the dual luciferase assay further confirmed that ATP2A2 is a downstream target of miR-210-5p. Additionally, silencing ATP2A2 resulted in increased cytoplasmic Ca2+ levels in PAMSCs. In MCT-induced PH, miR-210-5p promotes pulmonary vascular remodeling by inhibiting ATP2A2.

Nupr1-mediated vascular smooth muscle cell phenotype transformation involved in methamphetamine induces pulmonary hypertension

AimsNuclear protein 1 (Nupr1) is a multifunctional stress-induced protein involved in the regulation of tumorigenesis, apoptosis, and autophagy. However, its role in pulmonary hypertension (PH) after METH exposure remains unexplored. In this study, we aimed to investigate whether METH can induce PH and describe the role and mechanism of Nupr1 in the development of PH.Methods and resultsMice were made to induce pulmonary hypertension (PH) upon chronic intermittent treatment with METH. Their right ventricular systolic pressure (RVSP) was measured to assess pulmonary artery pressure. Pulmonary artery morphometry was determined by H&E staining and Masson staining. Nupr1 expression and function were detected in human lungs, mice lungs exposed to METH, and cultured pulmonary arterial smooth muscle cells (PASMCs) with METH treatment. Our results showed that chronic intermittent METH treatment successfully induced PH in mice. Nupr1 expression was increased in the cultured PASMCs, pulmonary arterial media from METH-exposed mice, and METH-ingested human specimens compared with control. Elevated Nupr1 expression promoted PASMC phenotype change from contractile to synthetic, which triggered pulmonary artery remodeling and resulted in PH formation. Mechanistically, Nupr1 mediated the opening of store-operated calcium entry (SOCE) by activating the expression of STIM1, thereby promoting Ca2+ influx and inducing phenotypic conversion of PASMCs.ConclusionsNupr1 activation could promote Ca2+ influx through STIM1-mediated SOCE opening, which promoted METH-induced pulmonary artery remodeling and led to PH formation. These results suggested that Nupr1 played an important role in METH-induced PH and might be a potential target for METH-related PH therapy.Graphical 1. Chronic intermittent methamphetamine exposure can induce the development of pulmonary arterial hypertension.2. Nupr1 plays a key role in the development of methamphetamine-related pulmonary arterial hypertension.3. Nupr1 mediates PASMCs phenotypic transformation via STIM1signal axis, which results in the development of methamphetamine-related pulmonary arterial hypertension.

SOCS5, targeted by miR-155-5p, plays a negative regulatory role in pulmonary hypertension through inhibiting JAK2/STAT3 signaling pathway

Pulmonary hypertension (PH) is a chronic pulmonary vascular disease and causes massive deaths. Here, we intended to investigate the function and mechanism of SOCS5 in PH. We engineered a hypoxia-induced PH model in mice. HE staining were implemented to evaluate pathological alterations in the lung tissues. The potential mechanism of SOCS5 in regulating hypoxia-induced pulmonary artery smooth muscle cell (PASMC) function was explored in vitro. RT-qPCR and western blot revealed that the level of SOCS5 was decreased both in PH mice and hypoxia-induced HPASMCs. Functional assays were performed for confirming the role of SOCS5 in modulating the cell phenotype and JAK2/STAT3 pathway in HPASMCs. Results revealed that overexpression of SOCS5 suppressed proliferation, migration and contraction of HPASMCs and negatively regulated the JAK2/STAT3 signaling pathway in HPASMCs under hypoxia in vitro, while knockdown of SOCS5 accelerated it. As evidenced by mechanism studies, SOCS5 was targeted and regulated by miR-155-5p, hence affecting on HPASMC proliferation, migration and contraction. These outcomes indicated that the decreased level of SOCS5 in hypoxia-induced HPASMCs promoted the cell proliferation, cell migration, and cell contraction through activating JAK2/STAT3 signaling pathway. Moreover, SOCS5 was targeted by miR-155-5p. All in all, our work hinted that miR-155-5p/SOCS5/JAK2/STAT3 axis played a crucial part in PH.

Circulating acetylcholine serves as a potential biomarker role in pulmonary hypertension

BackgroundAn increased acetylcholine (ACh) level in the right ventricle tissue of pulmonary hypertension (PH) was revealed, which indicated the important role of ACh in disease pathogenesis. However, the relationship between plasma ACh levels and disease conditions and patients’ prognosis has not been investigated. We aimed to explore the association between plasma ACh levels and the prognosis of patients with PH. We also discussed the feasibility of plasma ACh as a biomarker, which may contribute to the management of PH patients in the future.MethodsPatients with confirmed PH in Fuwai Hospital from April 2019 to August 2020 were enrolled. The primary clinical outcome in this study was defined as a composite outcome, including death/lung transplantation, heart failure, and worsening of symptoms. Fasting plasma was collected to detect the ACh levels. The association between ACh levels and patients’ prognosis was explored.ResultsFinally, four hundred and eight patients with PH were enrolled and followed for a mean period of 2.5 years. Patients in the high ACh group had worse World Health Organization Functional Class (WHO-FC), lower 6-minute walk distance (6 MWD), and higher N-terminal pro-brain natriuretic peptide (NT-proBNP). Notably, echocardiographic and hemodynamic parameters in the high metabolite group also suggested a worse disease condition compared with the low ACh group. After adjusting for confounders, compared with low ACh patients, those with high metabolite levels still have worse prognoses characterized as elevated risk of mortality, heart failure, and symptoms worsening.ConclusionHigh circulating ACh levels were associated with severe PH conditions and poor prognosis, which might serve as a potential biomarker in PH.

Right ventricular fibrosis in adults with uncorrected secundum atrial septal defect and pulmonary hypertension: a cardiovascular magnetic resonance study with late gadolinium enhancement, native T1 and extracellular volume.

Right ventricular (RV) fibrosis represents both adaptive and maladaptive responses to the overloaded RV condition. Its role in pulmonary hypertension (PH) associated with secundum atrial septal defect (ASD), which is the most common adult congenital heart disease (CHD), remains poorly understood. We enrolled 65 participants aged ≥18 years old with uncorrected secundum ASD who had undergone clinically indicated right heart catheterization (RHC), divided into the non-PH group (n = 7), PH group (n = 42), and Eisenmenger syndrome (ES) group (n = 16). We conducted cardiovascular magnetic resonance (CMR) studies with late gadolinium enhancement (LGE) imaging, native T1 mapping, and extracellular volume (ECV) measurement to evaluate the extent and clinical correlates of RV fibrosis. LGE was present in 94% of the population and 86% of the non-PH group, mostly located at the right ventricular insertion point (RVIP) regions. LGE in the septal and inferior RV region was predominantly observed in the ES group compared to the other groups (p = 0.031 and p < 0.001, respectively). The mean LGE scores in the ES and PH groups were significantly higher than those in the non-PH group (3.38 ± 0.96 vs. 2.74 ± 1.04 vs. 1.57 ± 0.79; p = 0.001). The ES and PH groups had significantly higher degrees of interstitial RV fibrosis compared to those in the non-PH group, indicated by native T1 (1,199.9 ± 68.9 ms vs. 1,131.4 ± 47.8 ms vs. 1,105.4 ± 44.0 ms; p < 0.001) and ECV (43.6 ± 6.6% vs. 39.5 ± 4.9% vs. 39.4 ± 5.8%; p = 0.037). Additionally, native T1 significantly correlated with pulmonary vascular resistance (r = 0.708, p < 0.001), RV ejection fraction (r = -0.468, p < 0.001) and peripheral oxygen saturation (r = -0.410, p = 0.001). In patients with uncorrected secundum ASD, RV fibrosis may occur before the development of PH and progressively intensify alongside the progression of PH severity. A higher degree of RV fibrosis, derived from CMR imaging, correlates with worse hemodynamics, RV dysfunction, and poorer clinical conditions.

Abstract 15964: Ferroptosis Integrates Mitochondrial Dysfunction and Pathological Inflammation to Promote Pulmonary Hypertension

Introduction: Ferroptosis is an iron-dependent, mitochondrial-mediated, non-apoptotic, highly inflammatory form of cell death. Ferroptosis plays important roles in numerous disease states via activation of complement and NLRP3 inflammasome, but its role in pulmonary hypertension (PH) is less well defined. Methods: Male Sprague Dawley rats were randomized into 3 groups: control, monocrotaline-vehicle (MCT-V), and MCT rats treated with ferrostatin-1 (MCT-FI). Pulmonary vascular disease severity and right ventricular function were assessed with histology, echocardiography, and pressure-volume loop analysis. Mitochondrial enrichments from lung tissue were subjected to quantitative proteomics. RNAseq evaluated global lung expression changes. KEGG analysis was performed on proteomics and RNAseq datasets to delineate which pathways were most associated with PH severity and modulated by ferrostatin-1 treatment. The hemodynamic effects of single-nucleotide polymorphisms in GPX4 were evaluated in the BioVU dataset. Results: Ferroptosis inhibition reduced right ventricular systolic pressure and improved RV function in MCT rats. Proteomics analysis identified a link between ferroptosis and multiple metabolic pathways that were associated with PH severity. RNAseq demonstrated ferroptosis inhibition partially suppressed complement and inflammatory signaling. Finally, patients with SNP rs1444732 in GPX4 had a higher pulmonary vascular resistance and mean pulmonary arterial pressure. Conclusions: Ferroptosis may integrate disrupted metabolism and inflammation to promote pulmonary vascular disease.

Targeting IL-11 system as a treatment of pulmonary arterial hypertension

IL-11 is linked to fibrotic diseases, but its role in pulmonary hypertension is unclear. We examined IL-11's involvement in idiopathic pulmonary arterial hypertension (iPAH). Using samples from control (n = 20) and iPAH (n = 6) subjects, we assessed IL-11 and IL-11Rα expression and localization through RT-qPCR, ELISA, immunohistochemistry, and immunofluorescence. A monocrotaline-induced PAH model helped evaluate the impact of siRNA-IL-11 on pulmonary artery remodeling and PH. The effects of recombinant human IL-11 and IL-11Rα on human pulmonary artery smooth muscle cell (HPASMC) proliferation, pulmonary artery endothelial cell (HPAEC) mesenchymal transition, monocyte interactions, endothelial tube formation, and precision cut lung slice (PCLS) pulmonary artery remodeling and contraction were evaluated. IL-11 and IL-11Rα were over-expressed in pulmonary arteries (3.2-fold and 75-fold respectively) and serum (1.5-fold and 2-fold respectively) of patients with iPAH. Therapeutic transient transfection with siRNA targeting IL-11 resulted in a significant reduction in pulmonary artery remodeling (by 98%), right heart hypertrophy (by 66%), and pulmonary hypertension (by 58%) in rats exposed to monocrotaline treatment. rhIL-11 and soluble rhIL-11Rα induce HPASMC proliferation and HPAEC to monocyte interactions, mesenchymal transition, and tube formation. Neutralizing monoclonal IL-11 and IL-11Rα antibodies inhibited TGFβ1 and EDN-1 induced HPAEC to mesenchymal transition and HPASMC proliferation. In 3D PCLS, rhIL-11 and soluble rhIL-11Rα do not promote pulmonary artery contraction but sensitize PCLS pulmonary artery contraction induced by EDN-1.In summary, IL-11 and IL-11Rα are more highly expressed in the pulmonary arteries of iPAH patients and contribute to pulmonary artery remodeling and the development of PH.

Serum Metabolomic Profile in Hypoxia-Induced Pulmonary Hypertension Mice after C75 Treatment.

Inhibition of fatty acid synthase (FAS) plays a crucial protective role in pulmonary hypertension (PH). Our aim was to identify novel metabolites in mice with hypoxia-induced PH after treatment with C75 (FAS inhibitor) and to confirm the presence of these metabolites in paediatric patients with PH. The PH mouse model was built by chronic hypoxia and ovalbumin (OVA) assistance. Untargeted metabolomics was used to analyse mouse serum. Six children with PH and six relative controls (patients without lung and heart disease) were selected in Shanghai Children's Hospital and they all performed blood tandem mass spectrometry during hospitalization. First, a total of 29 differential metabolites, including lipid metabolites, polyamine, and glutamine were identified as differential metabolites in the hypoxia group compared with the control group. After C75 treatment, symptoms were partially relieved in the PH mouse, and 15 differential metabolites, including lipid metabolites, polyamine, and glutamine were identified in the hypoxia + C75 group compared with the hypoxia group. These differential metabolites were enriched in arginine and glycerolipid metabolism through metabolite set enrichment analyses and were involved in excessive cell proliferation, which was a characteristic of PH. Second, glutamine and caproyl carnitine levels were increased in paediatric patients with PH. FAS may be a potential PH therapeutic target. Lipid metabolites, polyamine, and glutamine, are closely related to PH. Putrescine and glutamine might be biomarkers for PH.

Endothelial cell senescence exacerbates pulmonary hypertension by inducing juxtacrine Notch signaling in smooth muscle cells

Pulmonary arterial hypertension (PAH) is a fatal disease characterized by a progressive increase in pulmonary artery pressure caused by pathological pulmonary artery remodeling. Here, we demonstrate that endothelial cell (EC) senescence plays a negative role in pulmonary hypertension via juxtacrine interaction with smooth muscle cells (SMCs). By using EC-specific progeroid mice, we discovered that EC progeria deteriorated vascular remodeling in the lungs, and exacerbated pulmonary hypertension in mice. Mechanistically, senescent ECs overexpressed Notch ligands, which resulted in increased Notch signaling and activated proliferation and migration capacities in neighboring SMCs. Pharmacological inhibition of Notch signaling reduced the effects of senescent ECs on SMCs functions invitro, and improved the worsened pulmonary hypertension in EC-specific progeroid mice invivo. Our findings show that EC senescence is a critical disease-modifying factor in PAH and that EC-mediated Notch signaling is a pharmacotherapeutic target for the treatment of PAH, particularly in the elderly.

The role of pulmonary hypertension in the postoperative evolution of lung cancer patients

The role of pulmonary hypertension in the postoperative evolution of lung cancer patients

Updated perspective of EPAS1 and the role in pulmonary hypertension.

Pulmonary hypertension (PH) is a group of syndromes characterized by irreversible vascular remodeling and persistent elevation of pulmonary vascular resistance and pressure, leading to ultimately right heart failure and even death. Current therapeutic strategies mainly focus on symptoms alleviation by stimulating pulmonary vessel dilation. Unfortunately, the mechanism and interventional management of vascular remodeling are still yet unrevealed. Hypoxia plays a central role in the pathogenesis of PH and numerous studies have shown the relationship between PH and hypoxia-inducible factors family. EPAS1, known as hypoxia-inducible factor-2 alpha (HIF-2α), functions as a transcription factor participating in various cellular pathways. However, the detailed mechanism of EPAS1 has not been fully and systematically described. This article exhibited a comprehensive summary of EPAS1 including the molecular structure, biological function and regulatory network in PH and other relevant cardiovascular diseases, and furthermore, provided theoretical reference for the potential novel target for future PH intervention.

Galectin-3 Expression Promotes Pulmonary Hypertension Through Multiple Mechanisms

Pulmonary Hypertension is a progressive vascular disease resulting from the tapering of pulmonary arteries causing high pulmonary arterial blood pressure and ultimately right ventricular failure. A defining characteristic of Pulmonary Hypertension is the excessive remodeling of pulmonary arteries that includes increased proliferation, vascular fibrosis and inflammation. There is no outward cure for Pulmonary Hypertension nor are there interventions that effectively impede or reverse pulmonary arterial remodeling, and pulmonary vascular research over the past several decades has sought to identify novel molecular mechanisms to target for therapeutic benefit. Galectin-3 is a carbohydrate binding lectin that is unique for its chimeric structure, comprised of an N-terminal oligomerization domain and a C-terminal carbohydrate-recognition domain. Galectin-3 is a regulator of modifications in cell behavior that contribute to aberrant pulmonary arterial remodeling including cell proliferation, inflammation, and fibrosis, but its role in Pulmonary Hypertension is poorly understood. In this review, we define Galectin-3 and summarize specific topics regarding the role of Galectin-3 expression in the development of Pulmonary Hypertension by providing evidence which supports the ability of Galectin-3 to influence reactive oxygen species production, NADPH enzyme expression, vascular inflammation and vascular fibrosis, all phenomena which contribute to pulmonary arterial remodeling and the development of Pulmonary Hypertension.

Eliminating Senescent Cells Can Promote Pulmonary Hypertension Development and Progression.

Senescent cells (SCs) are involved in proliferative disorders, but their role in pulmonary hypertension remains undefined. We investigated SCs in patients with pulmonary arterial hypertension and the role of SCs in animal pulmonary hypertension models. We investigated senescence (p16, p21) and DNA damage (γ-H2AX, 53BP1) markers in patients with pulmonary arterial hypertension and murine models. We monitored p16 activation by luminescence imaging in p16-luciferase (p16LUC/+) knock-in mice. SC clearance was obtained by a suicide gene (p16 promoter-driven killer gene construct in p16-ATTAC mice), senolytic drugs (ABT263 and cell-permeable FOXO4-p53 interfering peptide [FOXO4-DRI]), and p16 inactivation in p16LUC/LUC mice. We investigated pulmonary hypertension in mice exposed to normoxia, chronic hypoxia, or hypoxia+Sugen, mice overexpressing the serotonin transporter (SM22-5-HTT+), and rats given monocrotaline. Patients with pulmonary arterial hypertension compared with controls exhibited high lung p16, p21, and γ-H2AX protein levels, with abundant vascular cells costained for p16, γ-H2AX, and 53BP1. Hypoxia increased thoracic bioluminescence in p16LUC/+ mice. In wild-type mice, hypoxia increased lung levels of senescence and DNA-damage markers, senescence-associated secretory phenotype components, and p16 staining of pulmonary endothelial cells (P-ECs, 30% of lung SCs in normoxia), and pulmonary artery smooth muscle cells. SC elimination by suicide gene or ABT263 increased the right ventricular systolic pressure and hypertrophy index, increased vessel remodeling (higher dividing proliferating cell nuclear antigen-stained vascular cell counts during both normoxia and hypoxia), and markedly decreased lung P-ECs. Pulmonary hemodynamic alterations and lung P-EC loss occurred in older p16LUC/LUC mice, wild-type mice exposed to Sugen or hypoxia+Sugen, and SM22-5-HTT+ mice given either ABT263 or FOXO4-DRI, compared with relevant controls. The severity of monocrotaline-induced pulmonary hypertension in rats was decreased slightly by ABT263 for 1 week but was aggravated at 3 weeks, with loss of P-ECs. Elimination of senescent P-ECs by senolytic interventions may worsen pulmonary hemodynamics. These results invite consideration of the potential impact on pulmonary vessels of strategies aimed at controlling cell senescence in various contexts.

Dysfunctional Mitochondria and Hemolysis are Linked by Impaired Maturation of Reticulocytes: Possible Role in Pulmonary Hypertension

IntroductionWe previously demonstrated that significantly elevated levels of circulating free heme (CFH) is associated with preclinical (Sugen/Hypoxia in rats) pulmonary hypertension (PH) and clinical pulmonary arterial hypertension (PAH). However, the pathogenic mechanisms of free heme release in PAH patients and animal models in the absence of hemolytic disease are yet to be elucidated.HypothesisThe mitochondria play a crucial role in reticulocyte maturation (precursors to red blood cells). Our hypothesis tests if mitochondrial dysfunction (MD) impaired reticulocyte maturation increases its fragility and causes rupture, elevating CFH levels that promote PAH.MethodsRecently reported genetic PH rat models carrying the NFU1G206C mutation spontaneously develop PH with severe MD. Erythropoiesis activation, reticulocyte counts, and CFH levels were monitored in this model. ChemiDoc imaging system was used to visualize FITC‐dextran extravasation in fresh transversely cut pulmonary slices 24 hours after FITC‐dextran injection (60 mg/kg. i.v.). Changes in right ventricle (RV) hemodynamics were used to determine the level of disease severity. Pulmonary artery smooth muscle cells (PASMCs) isolated from wild‐type (WT) and NFU1G206C rats were used to evaluate effects of free heme in vitro. Matrigel assay was used to evaluate the tube formation potential of endothelial cells (EC’s).ResultsThe NFU1G206C rats showed significantly higher erythropoietin levels and immature reticulocyte counts compared to WTs. Correspondingly, significantly elevated plasma free heme and extravasation of FITC‐dextran into lung parenchyma were observed, indicating pulmonary endothelial barrier dysfunction, previously demonstrated as an essential contributor to PH pathobiology. Notably, treatment of human pulmonary artery EC’s with 50µM heme completely abolished EC tube formation, indicating that CFH could trigger a cellular environment leading to PH. Additionally, exposing isolated PASMC from NFU1G206C to 50µM heme increased the proliferation rate by ~1.5 and ~2.9 folds compared to untreated NFU1G206C or WT PASMC. Chronic lipoic acid (LA) supplementation to restore mitochondrial function (1.7mM orally), normalized total/immature reticulocyte counts in NFU1G206C rats (WT/NFU1G206C/NFU1G206C+LA for total and immature reticulocyte, p&lt;0.002 and p&lt;0.001) and fully reversed the PAH phenotype. Alternatively, the RV systolic pressure of NFU1G206C rats was significantly (p&lt;0.0001) attenuated by blocking the heme transporter (HCP1) with sulfasalazine (SL, 20mg/ml/kg, i.p.).ConclusionWe show that mitochondrial dysfunction impaired reticulocyte maturation promotes hemolysis resulting in increased CFH. Elevated CFH can trigger pathogenic pathways leading to PH/PAH via EC barrier dysfunction and increased PASMC proliferation. Treatment approaches that improve mitochondrial metabolism (LA) or inhibit free heme entrance to the cell (SL) abrogate the PH phenotype, highlighting the critical role of free heme‐induced signaling in disease pathobiology.

FGF21 alleviates pulmonary hypertension by inhibiting mTORC1/EIF4EBP1 pathway via H19.

Long non‐coding RNAs (lncRNAs) play a significant role in pulmonary hypertension (PH). Our preliminary data showed that hypoxia‐induced PH is attenuated by fibroblast growth factor 21 (FGF21) administration. Therefore, we further investigated the regulatory role of long non‐coding RNAs in PH treated with FGF21. RNA sequencing analysis and real‐time PCR identified a significantly up‐regulation of the H19 after FGF21 administration. Moreover, gain‐ and loss‐of‐function assays demonstrated that FGF21 suppressed hypoxia‐induced proliferation of pulmonary artery smooth muscle cells partially through upregulation of H19. In addition, FGF21 deficiency markedly exacerbated hypoxia‐induced increases of pulmonary artery pressure and pulmonary vascular remodelling. In addition, AAV‐mediated H19 overexpression reversed the malignant phenotype of FGF21 knockout mice under hypoxia expose. Further investigation uncovered that H19 also acted as an orchestra conductor that inhibited the function of mechanistic target of rapamycin complex 1 (mTORC1) by disrupting the interaction of mTORC1 with eukaryotic translation initiation factor 4E–binding protein 1 (EIF4EBP1). Our work highlights the important role of H19 in PH treated with FGF21 and suggests a mechanism involving mTORC1/EIF4EBP1 inhibition, which may provide a fundamental for clinical application of FGF21 in PH.

Role of Pulmonary Hypertension in Acute Exacerbation of Chronic Obstructive Pulmonary Disease; Outcomes and Healthcare Utilization

<h3>Purpose</h3> Pulmonary hypertension (PH) is a common complication of chronic obstructive pulmonary disease (COPD). Mortality in COPD and PH has significantly improved due to advances made in the field, however, the effect of PH during acute exacerbation of COPD (AECOPD) remains unknown. We aim to analyze the outcomes, 30-day readmission rates, and healthcare resource utilization associated with PH in patients with AECOPD. <h3>Methods</h3> We used the 2016 and 2017 National Readmission Database with an inclusion criterion of AECOPD as a primary and PH as a secondary diagnosis using ICD 10-CM codes. Exclusion criteria were age under 18 years, non-elective admissions to better assess readmission rates and discharges in December. The primary outcome was in-hospital mortality during the index admission. Secondary outcomes were 30-day readmission rate, Length of stay (LOS), resource utilization, and instrument utilization including intubation, prolonged invasive mechanical ventilation >96hr (PIMV), tracheostomy, chest tube placement, and bronchoscopy during the index admission. <h3>Results</h3> A total of 627,848 patients with AECOPD were included in the study, and 68,429 (10.90 %) patients had a diagnosis of PH. PH was more common among females (61.14%) with a mean age of 71 ±11.66, Medicare recipients (79.5%), higher Charlson Comorbidity Index, and treatment in an urban teaching hospital. PH was associated with greater in-hospital mortality [Adjusted odds ratio (aOR): 1.89, p<0.001], higher 30-day readmission (aOR: 1.24, p<0.001), higher LOS [adjusted mean difference (aMD): 1.09, p<0.001], higher cost (aMD: $2785, p<0.01), and higher instrument utilization including intubation (aOR: 1.99, p<0.001), PIMV (aOR: 2.12, p<0.001), tracheostomy (aOR: 2.15, p<0.001), bronchoscopy (aOR:1.46, p=0.007) and chest tube placement (aOR: 1.39 p<0.004). <h3>Conclusion</h3> Our study indicates that PH is associated with greater in-hospital mortality, LOS, and 30-day readmission among patients with AECOPD. It is also associated with increased procedure utilization and higher healthcare resource utilization leading to increased hospital expenses. These factors lead to a detrimental effect on a patient's well-being and impact their quality of life. Prompt diagnosis and appropriate treatment of PH in patients with COPD may improve outcomes in these patients.

Endothelial cell ferroptosis mediates monocrotaline-induced pulmonary hypertension in rats by modulating NLRP3 inflammasome activation

Inflammation triggers pulmonary vascular remodelling. Ferroptosis, a nonapoptotic form of cell death that is triggered by iron-dependent lipid peroxidation and contributes to the pathogenesis of several inflammation-related diseases, but its role in pulmonary hypertension (PH) has not been studied. We examined endothelial cell ferroptosis in PH and the potential mechanisms. Pulmonary artery endothelial cells (PAECs) and lung tissues from monocrotaline (MCT)-induced PH rats were analysed for ferroptosis markers, including lipid peroxidation, the labile iron pool (LIP) and the protein expression of glutathione peroxidase 4 (GPX4), ferritin heavy chain 1 (FTH1) and NADPH oxidase-4 (NOX4). The effects of the ferroptosis inhibitor ferrostatin-1 (Fer-1) on endothelial cell ferroptosis and pulmonary vascular remodelling in MCT-induced rats were studied in vitro and in vivo. Ferroptosis was observed in PAECs from MCT-induced PH rats in vitro and in vivo and was characterized by a decline in cell viability accompanied by increases in the LIP and lipid peroxidation, the downregulation of GPX4 and FTH1 expression and the upregulation of NOX4 expression. High-mobility group box 1 (HMGB1)/Toll-like receptor 4 (TLR4)/NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome signalling was measured by western blotting. These changes were significantly blocked by Fer-1 administration in vitro and in vivo. These results suggest that Fer-1 plays a role in inhibiting ferroptosis-mediated PAEC loss during the progression of PH. The ferroptosis-induced inflammatory response depended on the activation of HMGB1/TLR4 signalling, which activated the NLRP3 inflammasome in vivo. We are the first to suggest that pulmonary artery endothelial ferroptosis triggers inflammatory responses via the HMGB1/TLR4/NLRP3 inflammasome signalling pathway in MCT-induced rats. Treating PH with a ferroptosis inhibitor and exploring new treatments based on ferroptosis regulation might be promising therapeutic strategies for PH.

Association of nutritional status and mortality risk in patients with primary pulmonary hypertension.

Malnutrition plays a crucial role in pulmonary hypertension (PH). The prognostic nutritional index (PNI) is a reliable indicator for nutritional status assessment. However, its relationship with mortality risk in PH patients has not yet been investigated. This study analyzed data from the Patient Registry for Primary PH. PNI was calculated through albumin and lymphocyte counts. Subjects with missing data for PNI calculation were excluded. The primary endpoint was all‐cause mortality. Cox proportional hazard model was used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs). Of the 317 patients records available in the registry, we finally included 136 patients. The average age of the included subjects was 40.56 (14.91) years and 63.24% (86/136) were female. In our analysis of Cox regression, per 1‐point increment of PNI was associated with 4% decreased risk of mortality in PH patients (age‐ and sex‐adjusted HR: 0.96, 95% CI: 0.93–0.98, p = 0.002). We further categorized these subjects by quartiles of PNI. Compared to quartile 4, the age‐ and sex‐adjusted HRs of death for quartiles 1, 2, and 3 were 2.39 (95% CI: 1.21–4.72, p = 0.01), 2.25 (95% CI: 1.15–4.39, p = 0.02), and 1.72 (95% CI: 0.84–3.52, p = 0.14). In addition, logistic regression analyses suggested a positive correlation of PNI with total lung capacity (β = 0.98, p = 0.002) and forced expiratory volume in 1 min (β = 1.53, p = 0.03). This study demonstrates that low PNI was associated with an increased risk of death in PH patients. These findings help to enlighten our understanding of the nutritional status and adverse outcomes in PH patients.