The Metabolic Theory of Pulmonary Arterial Hypertension

Inhibition of PIKfyve Ameliorates the Proliferation and Migration of Vascular Smooth Muscle Cells and Vascular Intima Hyperplasia By Reducing mTORC1 Activity

ABSTRACT

This study was designed to investigate the role and mechanism of PIKfyve in the proliferation and migration of vascular smooth muscle cells (VSMCs) and vascular intima hyperplasia. We first observed increased protein levels of PIKfyve, phospho (p)-S6 Ribosomal Protein (S6)Ser235/236, p-4EBP1Thr37/46 in VSMCs after 24 hours of platelet-derived growth factor (PDGF)-BB treatment. By using cell counting kit-8 assay, Ki-67 immunofluorescence staining and wound healing assay, we found that PIKfyve inhibition ameliorated the enhanced activity of VSMC proliferation and migration induced by PDGF-BB. Silencing PIKfyve also suppressed the phosphorylation of S6 and 4EBP1 (2 major effectors of mammalian target of rapamycin complex 1), glucose consumption, activity of hexokinase, and LDH in PDGF-BB-challenged VSMCs. After rescuing the phosphorylation of S6 and 4EBP1 by silencing Tsc1, the suppressive effects of PIKfyve inhibition on glucose utilization, proliferation, and migration in VSMCs were abolished. The animal model of vascular restenosis was established in C57BL/6J mice by wire injury. We found the expression of PIKfyve was increased in carotid artery at day 28 after injury. Reducing the activity of PIKfyve alleviated vascular neointima hyperplasia after injury. In conclusion, targeting PIKfyve might be a novel effective method to reduce the proliferation and migration of VSMCs and vascular restenosis by affecting mammalian target of rapamycin complex 1-mediated glucose utilization.

The Glycobiology of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive pulmonary vascular disease of complex etiology. Cases of PAH that do not receive therapy after diagnosis have a low survival rate. Multiple reports have shown that idiopathic PAH, or IPAH, is associated with metabolic dysregulation including altered bioavailability of nitric oxide (NO) and dysregulated glucose metabolism. Multiple processes such as increased proliferation of pulmonary vascular cells, angiogenesis, apoptotic resistance, and vasoconstriction may be regulated by the metabolic changes demonstrated in PAH. Recent reports have underscored similarities between metabolic abnormalities in cancer and IPAH. In particular, increased glucose uptake and altered glucose utilization have been documented and have been linked to the aforementioned processes. We were the first to report a link between altered glucose metabolism and changes in glycosylation. Subsequent reports have highlighted similar findings, including a potential role for altered metabolism and aberrant glycosylation in IPAH pathogenesis. This review will detail research findings that demonstrate metabolic dysregulation in PAH with an emphasis on glycobiology. Furthermore, this report will illustrate the similarities in the pathobiology of PAH and cancer and highlight the novel findings that researchers have explored in the field.

Adventitial Fibroblasts in Aortic Aneurysm: Unraveling Pathogenic Contributions to Vascular Disease

Aortic aneurysm (AA) is a degenerative vascular disease that involves aortic dilatation, and, if untreated, it can lead to rupture. Despite its significant impact on the healthcare system, its multifactorial nature and elusive pathophysiology contribute to limited therapeutic interventions that prevent the progression of AA. Thus, further research into the mechanisms underlying AA is paramount. Adventitial fibroblasts are one of the key constituents of the aortic wall, and they play an essential role in maintaining vessel structure and function. However, adventitial fibroblasts remain understudied when compared with endothelial cells and smooth muscle cells. Adventitial fibroblasts facilitate the production of extracellular matrix (ECM), providing structural integrity. However, during biomechanical stress and/or injury, adventitial fibroblasts can be activated into myofibroblasts, which move to the site of injury and secrete collagen and cytokines, thereby enhancing the inflammatory response. The overactivation or persistence of myofibroblasts has been shown to initiate pathological vascular remodeling. Therefore, understanding the underlying mechanisms involved in the activation of fibroblasts and in regulating myofibroblast activation may provide a potential therapeutic target to prevent or delay the progression of AA. This review discusses mechanistic insights into myofibroblast activation and associated vascular remodeling, thus illustrating the contribution of fibroblasts to the pathogenesis of AA.

Platelet-Derived TGF (Transforming Growth Factor)-β1 Enhances the Aerobic Glycolysis of Pulmonary Arterial Smooth Muscle Cells by PKM2 Upregulation

BACKGROUND

Metabolic reprogramming is a hallmark of pulmonary arterial hypertension. Platelet activation has been implicated in pulmonary arterial hypertension (PAH), whereas the role of platelet in the pathogenesis of PAH remains unclear.

METHODS

First, we explored the platelet function of SU5416/hypoxia mice and monocrotaline-injected rats PAH model. Then we investigated pulmonary arterial smooth muscle cell aerobic glycolysis after being treated with platelet supernatant. TGF (transforming growth factor)-βRI, PKM2, and other antagonists were applied to identify the underlying mechanism. In addition, platelet-specific deletion TGF-β1 mice were exposed to chronic hypoxia and SU5416. Cardiopulmonary hemodynamics, vascular remodeling, and aerobic glycolysis of pulmonary arterial smooth muscle cell were determined.

RESULTS

Here, we demonstrate that platelet-released TGF-β1 enhances the aerobic glycolysis of pulmonary arterial smooth muscle cells after platelet activation via increasing PKM2 expression. Mechanistically, platelet-derived TGF-β1 regulates PKM2 expression through mTOR (mammalian target of rapamycin)/c-Myc/PTBP1-hnRNPA1 pathway. Platelet TGF-β1 deficiency mice are significantly protected from SU5416 plus chronic hypoxia-induced PAH, including attenuated increases in right ventricular systolic pressure and less pulmonary vascular remodeling. Also, in Pf4cre⁺ Tgfb1^fl/fl mice, pulmonary arterial smooth muscle cells showed lower glycolysis capacity and their PKM2 expression decreased.

CONCLUSIONS

Our data demonstrate that TGF-β1 released by platelet contributes to the pathogenesis of PAH and further highlights the role of platelet in PAH.

Myeloid ecotropic viral integration site-1 inhibition promotes apoptosis, suppresses proliferation of acute myeloid leukemia cells, accentuates the effects of anticancer drugs

To investigate the effects of myeloid ecotropic viral integration site-1 (MEIS1) on the proliferation and apoptosis of acute myeloid leukemia (AML) cells and the anticancer effects of the drug, we screened Kasumi-6, KG-1, and Kasumi-1 cells using quantitative reverse transcription polymerase chain reaction. Kasumi-6 and Kasumi-1 cells were subjected to human antigen R (HuR)-mediated interference (IV). Hexokinase 2 (HK2) expression and phosphorylation of protein kinase B (p-AKT) and mammalian target of rapamycin (p-mTOR) were observed with Western blotting. Cell proliferation was assessed using Cell Counting Kit-8, apoptosis was examined using Hoechst 33,258 staining, and glucose uptake was detected with a colorimetric biochemical assay kit. We found that, among the three cell lines tested, MEIS1 expression was highest in Kasumi-1 cells, which were therefore selected for subsequent experiments. Kasumi-1 cells receiving IV showed significantly decreased proliferation (p < 0.05) and increased apoptosis compared to the control group. Compared with the controls, IV significantly increased the expression of HK2, p-AKT, p-mTOR, multidrug resistance-associated protein 1 and P-glycoprotein (P < 0.05), but decreased glucose uptake. Treatment with adriamycin, daunorubicin and imatinib resulted in a progressive increase in inhibition of cell proliferation, with the IV group showing the highest inhibition rate among the three groups (P < 0.05). Thus, inhibition of MEIS1 activity promoted apoptosis, inhibited the proliferation of Kasumi-1 and Kasumi-6 cells, and increaseed the anticancer effect of the drugs, suggesting that inhibition of MEIS1 may be a potential strategy for the treatment of AML.

Metabolic profile in endothelial cells of chronic thromboembolic pulmonary hypertension and pulmonary arterial hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary arterial hypertension (PAH) are two forms of pulmonary hypertension (PH) characterized by obstructive vasculopathy. Endothelial dysfunction along with metabolic changes towards increased glycolysis are important in PAH pathophysiology. Less is known about such abnormalities in endothelial cells (ECs) from CTEPH patients. This study provides a systematic metabolic comparison of ECs derived from CTEPH and PAH patients. Metabolic gene expression was studied using qPCR in cultured CTEPH-EC and PAH-EC. Western blot analyses were done for HK2, LDHA, PDHA1, PDK and G6PD. Basal viability of CTEPH-EC and PAH-EC with the incubation with metabolic inhibitors was measured using colorimetric viability assays. Human pulmonary artery endothelial cells (HPAEC) were used as healthy controls. Whereas PAH-EC showed significant higher mRNA levels of GLUT1, HK2, LDHA, PDHA1 and GLUD1 metabolic enzymes compared to HPAEC, CTEPH-EC did not. Oxidative phosphorylation associated proteins had an increased expression in PAH-EC compared to CTEPH-EC and HPAEC. PAH-EC, CTEPH-EC and HPAEC presented similar HOXD macrovascular gene expression. Metabolic inhibitors showed a dose-dependent reduction in viability in all three groups, predominantly in PAH-EC. A different metabolic profile is present in CTEPH-EC compared to PAH-EC and suggests differences in molecular mechanisms important in the disease pathology and treatment.

Metabolic Reprogramming of the Right Ventricle and Pulmonary Arteries in a Flow-Associated Pulmonary Arterial Hypertension Rat Model

Pulmonary arterial hypertension (PAH) is a complex devastating disease relevant to remarkable metabolic dysregulation. Although various research studies on PAH from a metabolic perspective have been emerging, pathogenesis of PAH varies in different categories. Research on metabolic reprogramming in flow-associated PAH remains insufficient. An untargeted metabolomic profiling platform was used to evaluate the metabolic profile of pulmonary arteries (PAs) as well as the right ventricle (RV) in a flow-associated PAH rat model in the present work. A total of 79 PAs and 128 RV metabolites were significantly altered in PAH rats, among which 39 metabolites were assessed as shared dysregulated metabolites in PAs and the RV. Pathway analysis elucidated that, in PAs of PAH rats, pathways of phenylalanine, tyrosine, and tryptophan biosynthesis and linoleic acid metabolism were significantly altered, while in the RV, arginine biosynthesis and linoleic acid metabolism were altered dramatically. Further integrated analysis of shared dysregulated PA and RV metabolites demonstrated that the linoleic acid metabolism and the arachidonic acid (AA) metabolism were the key pathways involved in the pathogenesis of flow-associated PAH. Results obtained from the present work indicate that the PAH pathogenesis could be mediated by widespread metabolic reprogramming. In particular, the dysregulation of AA metabolism may considerably contribute to the development of high blood flow-associated PAH.

Potential biomarkers and therapeutic targets of idiopathic pulmonary arterial hypertension

BACKGROUND

Peripheral blood mononuclear cells (PBMCs) play an important role in the pathogenesis of pulmonary arterial hypertension (PAH). However, the specific roles of PBMCs in the development and progression of idiopathic PAH (IPAH) have not been fully understood.

METHODS

Here, differentially expressed genes (DEGs) of PBMCs or lung tissues between IPAH patients and healthy controls were identified via bioinformatics analysis of Gene Expression Omnibus (GEO) datasets GSE33463 and GSE48149, respectively. Subsequently, extensive target prediction and network analysis were performed to assess protein-protein interaction (PPI) networks, Gene Ontology (GO) terms, and pathway enrichment for DEGs. Co-expressed DEGs between PBMCs and lung tissues coupled with corresponding predicted miRNAs involved in PAH were also assessed. We identified 251 DEGs in PBMCs and 151 DEGs in lung tissue samples from IPAH. PDK4, RBPMS2, and PDE5A expression were altered in both PBMCs and lung tissues from IPAH patients compared to healthy control.

RESULTS

CXCL8, JUN, TLR8, IL1B, and TLR7 could be implicated as the hub genes in PBMCs, whereas ENO1, STAT1, CXCL10, GPI, and IRF1 in lung tissues. Finally, co-expressed DEGs of PDK4, RBPMS2, and PDE5A coupled with corresponding predicted miRNAs, especially miR-103a-3p, miR-185-5p, and miR-515-5p, are significantly associated with IPAH.

CONCLUSION

Our findings collectively suggest that the expression levels of PDK4, RBPMS2, and PDE5A in PBMCs are associated with the expression of these genes in lung tissues. Thus, these molecules may serve as potential circulating biomarkers and/or possible therapeutic targets for IPAH.

Proteomic analysis reveals that Xbp1s promotes hypoxic pulmonary hypertension through the p-JNK MAPK pathway

Hypoxic pulmonary hypertension (HPH) is characterized by elevated pulmonary artery resistance and vascular remodeling. Endoplasmic reticulum stress (ERS) is reported to be involved in HPH, but the underlying mechanisms remain uncertain. We found that Xbp1s, a potent transcription factor during ERS, was elevated in hypoxic-cultured rat PASMCs and lung tissues from HPH rats. Our in vitro experiments demonstrated that overexpressing Xbp1s can promote proliferation, cell viability, and migration and inhibit the apoptosis of PASMCs, while silencing Xbp1s led to the opposite. Through data-independent acquisition (DIA) mass spectrometry, we identified extensive proteomic alterations regulated by hypoxia and Xbp1s. Further validation revealed that p-JNK, rather than p-ERK or p-p38, was the downstream effector of Xbp1s. p-JNK inhibition reversed the biological effects of Xbp1s overexpression in vitro. In the animal HPH model, rats were randomly assigned to five groups: normoxia, hypoxia, hypoxia+AAV-CTL (control), hypoxia+AAV-Xbp1s (prevention), and hypoxia+AAV-Xbp1s (therapy). Adeno-associated virus (AAV) serotype 1-mediated Xbp1s knockdown in the prevention and therapy groups significantly reduced right ventricular systolic pressure, total pulmonary resistance, right ventricular hypertrophy, and the medial wall thickness of muscularized distal pulmonary arterioles; AAV-Xbp1s also decreased proliferating cell nuclear antigen expression and increased apoptosis in pulmonary arterioles. Collectively, our findings demonstrated that the Xbp1s-p-JNK pathway is important in hypoxic vascular remodeling and that targeting this pathway could be an effective strategy to prevent and alleviate HPH development.

SNPs for Genes Encoding the Mitochondrial Proteins Sirtuin3 and Uncoupling Protein 2 Are Associated With Disease Severity, Type 2 Diabetes, and Outcomes in Patients With Pulmonary Arterial Hypertension and This Is Recapitulated in a New Mouse Model Lacking Both Genes

Background

Isolated loss‐of‐function single nucleotide polymorphisms (SNPs) for SIRT3 (a mitochondrial deacetylase) and UCP2 (an atypical uncoupling protein enabling mitochondrial calcium entry) have been associated with both pulmonary arterial hypertension (PAH) and insulin resistance, but their collective role in animal models and patients is unknown.

Methods and Results

In a prospective cohort of patients with PAH (n=60), we measured SNPs for both SIRT3 and UCP2, along with several clinical features (including invasive hemodynamic data) and outcomes. We found SIRT3 and UCP2 SNPs often both in the same patient in a homozygous or heterozygous manner, correlating positively with PAH severity and associated with the presence of type 2 diabetes and 10‐year outcomes (death and transplantation). To explore this mechanistically, we generated double knockout mice for Sirt3 and Ucp2 and found increasing severity of PAH (mean pulmonary artery pressure, right ventricular hypertrophy/dilatation and extensive vascular remodeling, including inflammatory plexogenic lesions, in a gene dose‐dependent manner), along with insulin resistance, compared with wild‐type mice. The suppressed mitochondrial function (decreased respiration, increased mitochondrial membrane potential) in the double knockout pulmonary artery smooth muscle cells was associated with apoptosis resistance and increased proliferation, compared with wild‐type mice.

Conclusions

Our work supports the metabolic theory of PAH and shows that these mice exhibit spontaneous severe PAH (without environmental or chemical triggers) that mimics human PAH and may explain the findings in our patient cohort. Our study offers a new mouse model of PAH, with several features of human disease that are typically absent in other PAH mouse models.

The Pathobiology of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension is characterized by obliteration and obstruction of the pulmonary arterioles that in turn results in high right ventricular afterload and right heart failure. The pathobiology of pulmonary arterial hypertension is complex, with contributions from multiple pathophysiologic processes that are regulated by a variety of molecular mechanisms. This nature likely explains the limited efficacy of our current therapies, which only target a small portion of the pathobiological mechanisms that underlie advanced disease. Here we review the pathobiology of pulmonary arterial hypertension, focusing on the systemic, cellular, and molecular mechanisms that underlie the disease.

The angiostatic peptide endostatin enhances mortality risk prediction in pulmonary arterial hypertension

Currently available noninvasive markers for assessing disease severity and mortality risk in pulmonary arterial hypertension (PAH) are unrelated to fundamental disease biology. Endostatin, an angiostatic peptide known to inhibit pulmonary artery endothelial cell migration, proliferation and survival in vitro, has been linked to adverse haemodynamics and shortened survival in small PAH cohorts. This observational cohort study sought to assess: 1) the prognostic performance of circulating endostatin levels in a large, multicentre PAH cohort; and 2) the added value gained by incorporating endostatin into existing PAH risk prediction models.

Endostatin ELISAs were performed on enrolment samples collected from 2017 PAH subjects with detailed clinical data, including survival times. Endostatin associations with clinical variables, including survival, were examined using multivariable regression and Cox proportional hazards models. Extended survival models including endostatin were compared to null models based on the REVEAL risk prediction tool and European Society of Cardiology/European Respiratory Society (ESC/ERS) low-risk criteria using likelihood ratio tests, Akaike and Bayesian information criteria and C-statistics.

Higher endostatin was associated with higher right atrial pressure, mean pulmonary arterial pressure and pulmonary vascular resistance, and with shorter 6-min walk distance (p<0.01). Mortality risk doubled for each log higher endostatin (hazard ratio 2.3, 95% CI 1.6–3.4, p<0.001). Endostatin remained an independent predictor of survival when incorporated into existing risk prediction models. Adding endostatin to REVEAL-based and ESC/ERS criteria-based risk assessment strategies improved mortality risk prediction.

Endostatin is a robust, independent predictor of mortality in PAH. Adding endostatin to existing PAH risk prediction strategies improves PAH risk assessment.

Endostatin is a robust, easily accessible biomarker of PAH severity and mortality that is mechanistically related to PAH pathogenesis. Incorporating endostatin into commonly used risk prediction strategies for PAH improves prediction of mortality.https://bit.ly/3kzGT0w

The Emerging Role of Fatty Acid Synthase in Hypoxia-Induced Pulmonary Hypertensive Mouse Energy Metabolism

Aims

This study is aimed at examining whether fatty acid synthase (FAS) can regulate mitochondrial function in hypoxia-induced pulmonary arterial hypertension (PAH) and its related mechanism.

Results

The expression of FAS significantly increased in the lung tissue of mice with hypoxia-induced PAH, and its pharmacological inhibition by C75 ameliorated right ventricle cardiac function as revealed by echocardiographic analysis. Based on transmission electron microscopy and Seahorse assays, the mitochondrial function of mice with hypoxia was abnormal but was partially reversed after C75 injection. In vitro studies also showed an increase in the expression of FAS in hypoxia-induced human pulmonary artery smooth muscle cells (HPASMCs), which could be attenuated by FAS shRNA as well as C75 treatment. Meanwhile, C75 treatment reversed hypoxia-induced oxidative stress and activated PI3K/AKT signaling. shRNA-mediated inhibition of FAS reduced its expression and oxidative stress levels and improved mitochondrial respiratory capacity and ATP levels of hypoxia-induced HPASMCs.

Conclusions

Inhibition of FAS plays a crucial role in shielding mice from hypoxia-induced PAH, which was partially achieved through the activation of PI3K/AKT signaling, indicating that the inhibition of FAS may provide a potential future direction for reversing PAH in humans.

Novel Experimental Therapies for Treatment of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive and devastating disease characterized by pulmonary artery vasoconstriction and vascular remodeling leading to vascular rarefaction with elevation of pulmonary arterial pressures and pulmonary vascular resistance. Often PAH will cause death from right heart failure. Current PAH-targeted therapies improve functional capacity, pulmonary hemodynamics and reduce hospitalization. Nevertheless, today PAH still remains incurable and is often refractory to medical therapy, underscoring the need for further research. Over the last three decades, PAH has evolved from a disease of unknown pathogenesis devoid of effective therapy to a condition whose cellular, genetic and molecular underpinnings are unfolding. This article provides an update on current knowledge and summarizes the progression in recent advances in pharmacological therapy in PAH.

Pulmonary arterial hypertension induces the release of circulating extracellular vesicles with oxidative content and alters redox and mitochondrial homeostasis in the brains of rats

Pulmonary arterial hypertension (PAH) is characterized by increased resistance of the pulmonary vasculature and afterload imposed on the right ventricle (RV). Two major contributors to the worsening of this disease are oxidative stress and mitochondrial impairment. This study aimed to explore the effects of monocrotaline (MCT)-induced PAH on redox and mitochondrial homeostasis in the RV and brain and how circulating extracellular vesicle (EV) signaling is related to these phenomena. Wistar rats were divided into control and MCT groups (60 mg/kg, intraperitoneal), and EVs were isolated from blood on the day of euthanasia (21 days after MCT injections). There was an oxidative imbalance in the RV, brain, and EVs of MCT rats. PAH impaired mitochondrial function in the RV, as seen by a decrease in the activities of mitochondrial complex II and citrate synthase and manganese superoxide dismutase (MnSOD) protein expression, but this function was preserved in the brain. The key regulators of mitochondrial biogenesis, namely, proliferator-activated receptor gamma coactivator 1-alpha and sirtuin 1, were poorly expressed in the EVs of MCT rats, and this result was positively correlated with MnSOD expression in the RV and negatively correlated with MnSOD expression in the brain. Based on these findings, we can conclude that the RV is severely impacted by the development of PAH, but this pathological injury may signal the release of circulating EVs that communicate with different organs, such as the brain, helping to prevent further damage through the upregulation of proteins involved in redox and mitochondrial function.

Resveratrol Prevents Right Ventricle Dysfunction, Calcium Mishandling, and Energetic Failure via SIRT3 Stimulation in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is characterized by pulmonary vessel remodeling; however, its severity and impact on survival depend on right ventricular (RV) failure. Resveratrol (RES), a polyphenol found in red wine, exhibits cardioprotective effects on RV dysfunction in PAH. However, most literature has focused on RES protective effect on lung vasculature; recent finding indicates that RES has a cardioprotective effect independent of pulmonary arterial pressure on RV dysfunction, although the underlying mechanism in RV has not been determined. Therefore, this study is aimed at evaluating sirtuin-3 (SIRT3) modulation by RES in RV using a monocrotaline- (MC-) induced PAH rat model. Myocyte function was evaluated by confocal microscopy as cell contractility, calcium signaling, and mitochondrial membrane potential (ΔΨm); cell energetics was assessed by high-resolution respirometry, and western blot and immunoprecipitation evaluated posttranslational modifications. PAH significantly affects mitochondrial function in RV; PAH is prone to mitochondrial permeability transition pore (mPTP) opening, thus decreasing the mitochondrial membrane potential. The compromised cellular energetics affects cardiomyocyte function by decreasing sarco-endoplasmic reticulum Ca²⁺-ATPase (SERCA) activity and delaying myofilament unbinding, disrupting cell relaxation. RES partially protects mitochondrial integrity by deacetylating cyclophilin-D, a critical component of the mPTP, increasing SIRT3 expression and activity and preventing mPTP opening. The preserved energetic capability rescues cell relaxation by maintaining SERCA activity. Avoiding Ca²⁺ transient and cell contractility mismatch by preserving mitochondrial function describes, for the first time, impairment in excitation-contraction-energetics coupling in RV failure. These results highlight the importance of mitochondrial energetics and mPTP in PAH.

Acetazolamide Improves Right Ventricular Function and Metabolic Gene Dysregulation in Experimental Pulmonary Arterial Hypertension

Background: Right ventricular (RV) performance is a key determinant of mortality in pulmonary arterial hypertension (PAH). RV failure is characterized by metabolic dysregulation with unbalanced anaerobic glycolysis, oxidative phosphorylation, and fatty acid oxidation (FAO). We previously found that acetazolamide (ACTZ) treatment modulates the pulmonary inflammatory response and ameliorates experimental PAH.

Objective: To evaluate the effect of ACTZ treatment on RV function and metabolic profile in experimental PAH.

Design/Methods: In the Sugen 5416/hypoxia (SuHx) rat model of severe PAH, RV transcriptomic analysis was performed by RNA-seq, and top metabolic targets were validated by RT-PCR. We assessed the effect of therapeutic administration of ACTZ in the drinking water on hemodynamics by catheterization [right and left ventricular systolic pressure (RVSP and LVSP, respectively)] and echocardiography [pulmonary artery acceleration time (PAAT), RV wall thickness in diastole (RVWT), RV end-diastolic diameter (RVEDD), tricuspid annular plane systolic excursion (TAPSE)] and on RV hypertrophy (RVH) by Fulton's index (FI) and RV-to-body weight (BW) ratio (RV/BW). We also examined myocardial histopathology and expression of metabolic markers in RV tissues.

Results: There was a distinct transcriptomic signature of RVH in the SuHx model of PAH, with significant downregulation of metabolic enzymes involved in fatty acid transport, beta oxidation, and glucose oxidation compared to controls. Treatment with ACTZ led to a pattern of gene expression suggestive of restored metabolic balance in the RV with significantly increased beta oxidation transcripts. In addition, the FAO transcription factor peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Pgc-1α) was significantly downregulated in untreated SuHx rats compared to controls, and ACTZ treatment restored its expression levels. These metabolic changes were associated with amelioration of the hemodynamic and echocardiographic markers of RVH in the ACTZ-treated SuHx animals and attenuation of cardiomyocyte hypertrophy and RV fibrosis.

Conclusion: Acetazolamide treatment prevents the development of PAH, RVH, and fibrosis in the SuHx rat model of severe PAH, improves RV function, and restores the RV metabolic profile.

Novel molecular insights and public omics data in pulmonary hypertension

Pulmonary hypertension is a rare disease with high morbidity and mortality which mainly affects women of reproductive age. Despite recent advances in understanding the pathogenesis of pulmonary hypertension, the high heterogeneity in the presentation of the disease among different patients makes it difficult to make an accurate diagnosis and to apply this knowledge to effective treatments. Therefore, new studies are required to focus on translational and personalized medicine to overcome the lack of specificity and efficacy of current management. Here, we review the majority of public databases storing 'omics' data of pulmonary hypertension studies, from animal models to human patients. Moreover, we review some of the new molecular mechanisms involved in the pathogenesis of pulmonary hypertension, including non-coding RNAs and the application of 'omics' data to understand this pathology, hoping that these new approaches will provide insights to guide the way to personalized diagnosis and treatment.

Glutaminolysis: A Driver of Vascular and Cardiac Remodeling in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a decimating ailment described by chronic precapillary pulmonary hypertension, an elevated mean pulmonary arterial pressure with a normal pulmonary capillary wedge pressure, and a raised pulmonary vascular resistance resulting in increased right ventricular afterload culminating in heart failure and death. Current PAH treatments regulate the vasodilatory/vasoconstrictory balance of pulmonary vessels. However, these treatment options are unable to stop the progression of, or reverse, an already established disease. Recent studies have advanced a metabolic dysregulation, featuring increased glutamine metabolism, as a mechanism driving PAH progression. Metabolic dysregulation in PAH leads to increased glutaminolysis to produce substrate to meet the high-energy requirement by hyperproliferative and apoptosis-resistant pulmonary vascular cells. This article explores the role of glutamate metabolism in PAH and how it could be targeted as an anti-remodeling therapeutic strategy.

Chronic Obstructive Pulmonary Disease and the Cardiovascular System: Vascular Repair and Regeneration as a Therapeutic Target

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide and encompasses chronic bronchitis and emphysema. It has been shown that vascular wall remodeling and pulmonary hypertension (PH) can occur not only in patients with COPD but also in smokers with normal lung function, suggesting a causal role for vascular alterations in the development of emphysema. Mechanistically, abnormalities in the vasculature, such as inflammation, endothelial dysfunction, imbalances in cellular apoptosis/proliferation, and increased oxidative/nitrosative stress promote development of PH, cor pulmonale, and most probably pulmonary emphysema. Hypoxemia in the pulmonary chamber modulates the activation of key transcription factors and signaling cascades, which propagates inflammation and infiltration of neutrophils, resulting in vascular remodeling. Endothelial progenitor cells have angiogenesis capabilities, resulting in transdifferentiation of the smooth muscle cells via aberrant activation of several cytokines, growth factors, and chemokines. The vascular endothelium influences the balance between vaso-constriction and -dilation in the heart. Targeting key players affecting the vasculature might help in the development of new treatment strategies for both PH and COPD. The present review aims to summarize current knowledge about vascular alterations and production of reactive oxygen species in COPD. The present review emphasizes on the importance of the vasculature for the usually parenchyma-focused view of the pathobiology of COPD.

Dynamic characterization of intestinal metaplasia in the gastric corpus mucosa of Atp4a-deficient mice

Parietal cells of the gastric mucosa contain a complex and extensive secretory membrane system that harbors gastric H⁺, K⁺-adenosine triphosphatase (ATPase), the enzyme primarily responsible for gastric lumen acidification. Here, we describe the characterization of mice deficient in the H⁺, K⁺-ATPase α subunit (Atp4a^−/−) to determine the role of this protein in the biosynthesis of this membrane system and the biology of the gastric mucosa. Atp4a^−/− mice were produced by gene targeting. Wild-type (WT) and Atp4a^−/− mice, paired for age, were examined at 10, 12, 14 and 16 weeks for histopathology, and the expression of mucin 2 (MUC2), α-methylacyl-CoA racemase (AMACR), Ki-67 and p53 proteins was analyzed by immunohistochemistry. For further information, phosphoinositide 3-kinase (PI3K), phosphorylated-protein kinase B (p-AKT), mechanistic target of rapamycin (mTOR), hypoxia-inducible factor 1α (HIF-1α), lactate dehydrogenase A (LDHA) and sirtuin 6 (SIRT6) were detected by Western blotting. Compared with the WT mice, hypochlorhydric Atp4a^−/− mice developed parietal cell atrophy and significant antral inflammation (lymphocyte infiltration) and intestinal metaplasia (IM) with elevated MUC2 expression. Areas of dysplasia in the Atp4a^−/− mouse stomach showed increased AMACR and Ki-67 expression. Consistent with elevated antral proliferation, tissue isolated from Atp4a^−/− mice showed elevated p53 expression. Next, we examined the mechanism by which the deficiency of the H⁺, K⁺-ATPase α subunit has an effect on the gastric mucosa. We found that the expression of phosphorylated-PI3K, p-AKT, phosphorylated-mTOR, HIF-1α, LDHA and SIRT6 was significantly higher in tissue from the Atp4a^−/− mice compared with the WT mice (P<0.05). The H⁺, K⁺-ATPase α subunit is required for acid-secretory activity of parietal cells in vivo, the normal development and cellular homeostasis of the gastric mucosa, and attainment of the normal structure of the secretory membranes. Chronic achlorhydria and hypergastrinemia in aged Atp4a^−/− mice produced progressive hyperplasia and mucolytic and IM, and activated the Warburg effect via PI3K/AKT/mTOR signaling.

Cannabidiol attenuates pulmonary arterial hypertension by improving vascular smooth muscle cells mitochondrial function

Rationale: Pulmonary arterial hypertension (PAH) is a chronic disease associated with enhanced proliferation of pulmonary artery smooth muscle cells (PASMCs) and dysfunctional mitochondria, and the clinical therapeutic option for PAH is very limited. Recent studies showed that cannabidiol (CBD), a non-psychoactive constituent of cannabinoids, possessed antioxidant effect towards several cardiovascular diseases, whereas the mechanistic effect of CBD in PAH is unknown.

Methods: In this study, the effects of CBD in PAH were determined by analyzing its preventive and therapeutic actions in PAH rodent models in vivo and PASMCs' proliferation test in vitro. Additionally, CBD's roles in mitochondrial function and oxidant stress were also assessed in PASMCs.

Results: We found that CBD reversed the pathological changes observed in both Sugen-hypoxia and monocrotaline-induced PAH rodent models in a cannabinoid receptors-independent manner. Our results also demonstrated that CBD significantly inhibited the PASMCs' proliferation in PAH mice with less inflammation and reactive oxygen species levels. Moreover, CBD alleviated rodent PAH by recovering mitochondrial energy metabolism, normalizing the hypoxia-induced oxidant stress, reducing the lactate overaccumulation and abnormal glycolysis.

Conclusions: Taken together, these findings confirm an important role for CBD in PAH pathobiology.

Mice with a specific deficiency of Pfkfb3 in myeloid cells are protected from hypoxia-induced pulmonary hypertension

BACKGROUND AND PURPOSE

Macrophage infiltration into the lungs is a characteristic of pulmonary hypertension (PH). Glycolysis is the main metabolic pathway for macrophage activation. However, the effect of macrophage glycolysis on the development of PH remains unknown. We investigated the effect of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKBF3), a critical enzyme of macrophage glycolysis, on PH development.

EXPERIMENTAL APPROACH

Lung tissues from PH patients were examined by immunostaining with macrophage markers. PH was induced in Wistar rats with SU5416/hypoxia and in mice with hypoxia. Lungs and macrophages were isolated for analysis by RT-PCR, western blot, flow cytometry, and immunostaining.

KEY RESULTS

Expression of glycolytic molecules was increased in circulating peripheral blood mononuclear cells (PBMCs) and lung macrophages of PH patients. These results were also found in lung macrophages of SU5416/hypoxia (Su/Hx)-induced PH rats and hypoxia-induced PH mice. PH was ameliorated in myeloid-specific Pfkfb3-deficient mice (Pfkfb3ΔMϕ ) or mice treated with the PFKFB3 inhibitor 3PO, compared with their controls. Alveolar macrophages of PH Pfkfb3ΔMϕ mice produced lower levels of growth factors and pro-inflammatory cytokines than those of control mice. Circulating myeloid cells and lung myeloid cells were much fewer in PH Pfkfb3ΔMϕ mice than controls. Mechanistically, overexpression of Hif1a or Hif2a in bone marrow-derived macrophages (BMDMs) cultured with bone marrow of Pfkfb3ΔMϕ mice restored the decreased expression of pro-inflammatory cytokines and growth factors.

CONCLUSIONS AND IMPLICATIONS

Myeloid Pfkfb3 deficiency protects mice from PH, thereby suggesting that myeloid PFKFB3 is one of the important targets in the therapeutic effect of PFKFB3 inhibition in PH treatment.

Iron Deficiency in Pulmonary Arterial Hypertension: A Deep Dive into the Mechanisms

Pulmonary arterial hypertension (PAH) is a severe cardiovascular disease that is caused by the progressive occlusion of the distal pulmonary arteries, eventually leading to right heart failure and death. Almost 40% of patients with PAH are iron deficient. Although widely studied, the mechanisms linking between PAH and iron deficiency remain unclear. Here we review the mechanisms regulating iron homeostasis and the preclinical and clinical data available on iron deficiency in PAH. Then we discuss the potential implications of iron deficiency on the development and management of PAH.

Adipokines and Metabolic Regulators in Human and Experimental Pulmonary Arterial Hypertension

Pulmonary hypertension (PH) is associated with meta-inflammation related to obesity but the role of adipose tissue in PH pathogenesis is unknown. We hypothesized that adipose tissue-derived metabolic regulators are altered in human and experimental PH. We measured circulating levels of fatty acid binding protein 4 (FABP-4), fibroblast growth factor -21 (FGF-21), adiponectin, and the mRNA levels of FABP-4, FGF-21, and peroxisome proliferator-activated receptor γ (PPARγ) in lung tissue of patients with idiopathic PH and healthy controls. We also evaluated lung and adipose tissue expression of these mediators in the three most commonly used experimental rodent models of pulmonary hypertension. Circulating levels of FABP-4, FGF-21, and adiponectin were significantly elevated in PH patients compared to controls and the mRNA levels of these regulators and PPARγ were also significantly increased in human PH lungs and in the lungs of rats with experimental PH compared to controls. These findings were coupled with increased levels of adipose tissue mRNA of genes related to glucose uptake, glycolysis, tricarboxylic acid cycle, and fatty acid oxidation in experimental PH. Our results support that metabolic alterations in human PH are recapitulated in rodent models of the disease and suggest that adipose tissue may contribute to PH pathogenesis.

Adaptation and Maladaptation of the Right Ventricle in Pulmonary Vascular Diseases

The right ventricle is coupled to the low-pressure pulmonary circulation. In pulmonary vascular diseases, right ventricular (RV) adaptation is key to maintain ventriculoarterial coupling. RV hypertrophy is the first adaptation to diminish RV wall tension, increase contractility, and protect cardiac output. Unfortunately, RV hypertrophy cannot be sustained and progresses toward a maladaptive phenotype, characterized by dilation and ventriculoarterial uncoupling. The mechanisms behind the transition from RV adaptation to RV maladaptation and right heart failure are unraveled. Therefore, in this article, we explain the main traits of each phenotype, and how some early beneficial adaptations become prejudicial in the long-term.

Lack of Contribution of p66shc to Pressure Overload-Induced Right Heart Hypertrophy

The leading cause of death in pulmonary arterial hypertension (PAH) is right ventricular (RV) failure (RVF). Reactive oxygen species (ROS) have been suggested to play a role in the development of RV hypertrophy (RVH) and the transition to RVF. The hydrogen peroxide-generating protein p66shc has been associated with left ventricular (LV) hypertrophy but its role in RVH is unclear. The purpose of this study was to determine whether genetic deletion of p66shc affects the development and/or progression of RVH and RVF in the pulmonary artery banding (PAB) model of RV pressure overload. The impact of p66shc on mitochondrial ROS formation, RV cardiomyocyte function, as well as on RV morphology and function were studied three weeks after PAB or sham operation. PAB in wild type mice did not affect mitochondrial ROS production or RV cardiomyocyte function, but induced RVH and impaired cardiac function. Genetic deletion of p66shc did also not alter basal mitochondrial ROS production or RV cardiomyocyte function, but impaired RV cardiomyocyte shortening was observed following PAB. The development of RVH and RVF following PAB was not affected by p66shc deletion. Thus, our data suggest that p66shc-derived ROS are not involved in the development and progression of RVH or RVF in PAH.

Astragaloside IV blocks monocrotaline‑induced pulmonary arterial hypertension by improving inflammation and pulmonary artery remodeling

Pulmonary arterial hypertension (PAH) is associated with increased inflammation and abnormal vascular remodeling. Astragaloside IV (ASIV), a purified small molecular saponin contained in the well-know herb, Astragalus membranaceus, is known to exert anti-inflammatory and anti-proliferation effects. Thus, the present study investigated the possible therapeutic effects of ASIV on monocrotaline (MCT)-induced PAH. Rats were administered a single intraperitoneal injection of MCT (60 mg/kg), followed by treatment with ASIV at doses of 10 and 30 mg/kg once daily for 21 days. Subsequently, right ventricle systolic pressure, right ventricular hypertrophy and serum inflammatory cytokines, as well as pathological changes of the pulmonary arteries, were examined. The effects of ASIV on the hypoxia-induced proliferation and apoptotic resistance of human pulmonary artery smooth muscle cells (HPASMCs) and the dysfunction of human pulmonary artery endothelial cells (HPAECs) were evaluated. MCT elevated pulmonary artery pressure and promoted pulmonary artery structural remodeling and right ventricular hypertrophy in the rats, which were all attenuated by both doses of ASIV used. Additionally, ASIV prevented the increase in the TNF-α and IL-1β concentrations in serum, as well as their gene expression in lung tissues induced by MCT. In in vitro experiments, ASIV attenuated the hypoxia-induced proliferation and apoptotic resistance of HPASMCs. In addition, ASIV upregulated the protein expression of p27, p21, Bax, caspase-9 and caspase-3, whereas it downregulated HIF-1α, phospho-ERK and Bcl-2 protein expression in HPASMCs. Furthermore, in HPAECs, ASIV normalized the increased release of inflammatory cytokines and the increased protein levels of HIF-1α and VEGF induced by hypoxia. On the whole, these results indicate that ASIV attenuates MCT-induced PAH by improving inflammation, pulmonary artery endothelial cell dysfunction, pulmonary artery smooth muscle cell proliferation and resistance to apoptosis.

Micro-RNA Analysis in Pulmonary Arterial Hypertension: Current Knowledge and Challenges

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The role of miRNAs in PAH is fast expanding, and it is increasingly difficult to identify which molecules have the highest translational potential.

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This review discusses the challenges in miRNA analysis and interpretation in PAH and highlights 4 promising miRNAs in this field.

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Additional pre-clinical studies and clinical trials are urgently needed to bring miRNAs from the bench to the bedside soon.

Pulmonary arterial hypertension (PAH) is a rare, chronic disease of the pulmonary vasculature that is associated with poor outcomes. Its pathogenesis is multifactorial and includes micro-RNA (miRNA) deregulation. The understanding of the role of miRNAs in PAH is expanding quickly, and it is increasingly difficult to identify which miRNAs have the highest translational potential. This review summarizes the current knowledge of miRNA expression in PAH, discusses the challenges in miRNA analysis and interpretation, and highlights 4 promising miRNAs in this field (miR-29, miR-124, miR-140, and miR-204).

Mitochondria-Associated Endoplasmic Reticulum Membranes in Cardiovascular Diseases

The endoplasmic reticulum (ER) and mitochondria are physically connected to form dedicated structural domains known as mitochondria-associated ER membranes (MAMs), which participate in fundamental biological processes, including lipid and calcium (Ca²⁺) homeostasis, mitochondrial dynamics and other related cellular behaviors such as autophagy, ER stress, inflammation and apoptosis. Many studies have proved the importance of MAMs in maintaining the normal function of both organelles, and the abnormal amount, structure or function of MAMs is related to the occurrence of cardiovascular diseases. Here, we review the knowledge regarding the components of MAMs according to their different functions and the specific roles of MAMs in cardiovascular physiology and pathophysiology, focusing on some highly prevalent cardiovascular diseases, including ischemia-reperfusion, diabetic cardiomyopathy, heart failure, pulmonary arterial hypertension and systemic vascular diseases. Finally, we summarize the possible mechanisms of MAM in cardiovascular diseases and put forward some obstacles in the understanding of MAM function we may encounter.

miR-150-PTPMT1-cardiolipin signaling in pulmonary arterial hypertension

Circulating levels of endothelial miR-150 are reduced in pulmonary arterial hypertension (PAH) and act as an independent predictor of patient survival, but links between endothelial miR-150 and vascular dysfunction are not well understood. We studied the effects of endothelial miR-150 supplementation and inhibition in PAH mice and cells from patients with idiopathic PAH. The role of selected mediators of miR-150 identified by RNA sequencing was evaluated in vitro and in vivo. Endothelium-targeted miR-150 delivery prevented the disease in Sugen/hypoxia mice, while endothelial knockdown of miR-150 had adverse effects. miR-150 target genes revealed significant associations with PAH pathways, including proliferation, inflammation, and phospholipid signaling, with PTEN-like mitochondrial phosphatase (PTPMT1) most markedly altered. PTPMT1 reduced inflammation and apoptosis and improved mitochondrial function in human pulmonary endothelial cells and blood-derived endothelial colony-forming cells from idiopathic PAH. Beneficial effects of miR-150 in vitro and in vivo were linked with PTPMT1-dependent biosynthesis of mitochondrial phospholipid cardiolipin and reduced expression of pro-apoptotic, pro-inflammatory, and pro-fibrotic genes, including c-MYB, NOTCH3, transforming growth factor β (TGF-β), and Col1a1. In conclusion, we are the first to show that miR-150 supplementation attenuates pulmonary endothelial damage induced by vascular stresses and may be considered as a potential therapeutic strategy in PAH.

Perivascular Inflammation in Pulmonary Arterial Hypertension

Perivascular inflammation is a prominent pathologic feature in most animal models of pulmonary hypertension (PH) as well as in pulmonary arterial hypertension (PAH) patients. Accumulating evidence suggests a functional role of perivascular inflammation in the initiation and/or progression of PAH and pulmonary vascular remodeling. High levels of cytokines, chemokines, and inflammatory mediators can be detected in PAH patients and correlate with clinical outcome. Similarly, multiple immune cells, including neutrophils, macrophages, dendritic cells, mast cells, T lymphocytes, and B lymphocytes characteristically accumulate around pulmonary vessels in PAH. Concomitantly, vascular and parenchymal cells including endothelial cells, smooth muscle cells, and fibroblasts change their phenotype, resulting in altered sensitivity to inflammatory triggers and their enhanced capacity to stage inflammatory responses themselves, as well as the active secretion of cytokines and chemokines. The growing recognition of the interaction between inflammatory cells, vascular cells, and inflammatory mediators may provide important clues for the development of novel, safe, and effective immunotargeted therapies in PAH.

Plasma metabolomics exhibit response to therapy in chronic thromboembolic pulmonary hypertension

Pulmonary hypertension is a condition with limited effective treatment options. Chronic thromboembolic pulmonary hypertension (CTEPH) is a notable exception, with pulmonary endarterectomy (PEA) often proving curative. This study investigated the plasma metabolome of CTEPH patients, estimated reversibility to an effective treatment and explored the source of metabolic perturbations.We performed untargeted analysis of plasma metabolites in CTEPH patients compared to healthy controls and disease comparators. Changes in metabolic profile were evaluated in response to PEA. A subset of patients were sampled at three anatomical locations and plasma metabolite gradients calculated.We defined and validated altered plasma metabolite profiles in patients with CTEPH. 12 metabolites were confirmed by receiver operating characteristic analysis to distinguish CTEPH and both healthy (area under the curve (AUC) 0.64-0.94, all p<2×10^-5) and disease controls (AUC 0.58-0.77, all p<0.05). Many of the metabolic changes were notably similar to those observed in idiopathic pulmonary arterial hypertension (IPAH). Only five metabolites (5-methylthioadenosine, N1-methyladenosine, N1-methylinosine, 7-methylguanine, N-formylmethionine) distinguished CTEPH from chronic thromboembolic disease or IPAH. Significant corrections (15-100% of perturbation) in response to PEA were observed in some, but not all metabolites. Anatomical sampling identified 188 plasma metabolites, with significant gradients in tryptophan, sphingomyelin, methionine and Krebs cycle metabolites. In addition, metabolites associated with CTEPH and gradients showed significant associations with clinical measures of disease severity.We identified a specific metabolic profile that distinguishes CTEPH from controls and disease comparators, despite the observation that most metabolic changes were common to both CTEPH and IPAH patients. Plasma metabolite gradients implicate cardiopulmonary tissue metabolism of metabolites associated with pulmonary hypertension and metabolites that respond to PEA surgery could be a suitable noninvasive marker for evaluating future targeted therapeutic interventions.

Lipocalin-2-induced proliferative endoplasmic reticulum stress participates in Kawasaki disease-related pulmonary arterial abnormalities

Clinical cases have reported pulmonary arterial structural and functional abnormalities in patients with Kawasaki disease (KD); however, the underlying mechanisms are unclear. In this study, a KD rat model was established via the intraperitoneal injection of Lactobacillus casei cell wall extract (LCWE). The results showed that pulmonary arterial functional and structural abnormalities were observed in KD rats. Furthermore, proliferative endoplasmic reticulum stress (ER stress) was observed in the pulmonary arteries of KD rats. Notably, the level of lipocalin-2 (Lcn 2), a trigger factor of inflammation, was remarkably elevated in the plasma and lung tissues of KD rats; increased Lcn 2 levels following LCWE stimulation may result from polymorphonuclear neutrophils (PMNs). Correspondingly, in cultured pulmonary artery smooth muscle cells (PASMCs), Lcn 2 markedly augmented the cleavage and nuclear localization of activating transcription factor-6 (ATF6), upregulated the transcription of glucose regulated protein 78 (GRP78) and neurite outgrowth inhibitor (NOGO), and promoted PASMCs proliferation. However, proapoptotic C/EBP homologous protein (CHOP) and caspase 12 levels were not elevated. Treatment with 4-phenyl butyric acid (4-PBA, a specific inhibitor of ER stress) inhibited PASMCs proliferation induced by Lcn 2 and attenuated pulmonary arterial abnormalities and right ventricular hypertrophy and reduced right ventricular systolic pressure in KD rats. In conclusion, Lcn 2 remarkably facilitates proliferative ER stress in PASMCs, which probably accounts for KD-related pulmonary arterial abnormalities.

Elevated Pulmonary Artery Systolic Pressure is Associated with Poor Survival of Patients with Non-Small Cell Lung Cancer

Purpose

Pulmonary hypertension (PH) is an important comorbidity of lung cancer, PH in lung cancer patients is gradually gaining interest because of its apparent high prevalence, but the impact of PH on the outcomes of lung cancer remains uncertain and had rarely been discussed. We aimed to evaluate the prevalence, determinants and prognosis value of elevated pulmonary artery systolic pressure (PASP) in non-small cell lung cancer patients.

Patients and Methods

In this retrospective study, subjects with a new and pathological confirmed diagnosis of lung cancer were enrolled. All patients underwent transthoracic echocardiography before received treatment. Pulmonary artery systolic pressure was measured by transthoracic echocardiography. Lung cancer subtypes were categorized by WHO classification of lung tumors. Hazard ratios (HR) were estimated by using Cox regression models.

Results

Among 612 non-small cell lung cancer (NSCLC) patients, 19.8% coexisted with PH. After adjustment for age, symptom, coagulation disorders, lymph node metastasis, distant metastasis, histological type, clinical stage, PASP ≥35mmHg was significantly associated with the decreased overall survival (OS) of NSCLC (P= 0.028). Moreover, PASP ≥45mmHg was an independent predictor for perioperative death. Independent factors of comorbid elevated PASP were age, the presence of intrapulmonary metastasis and coagulation disorders.

Conclusion

These findings suggest that PASP is an independent prognostic risk factor for NSCLC patients. Main determinants of elevated PASP are age, the presence of intrapulmonary metastasis and coagulation disorders.

The Role and Regulation of Pulmonary Artery Smooth Muscle Cells in Pulmonary Hypertension

Pulmonary hypertension (PH) is one of the most devastating cardiovascular diseases worldwide and it draws much attention from numerous scientists. As an indispensable part of pulmonary artery, smooth muscle cells are worthy of being carefully investigated. To elucidate the pathogenesis of PH, several theories focusing on pulmonary artery smooth muscle cells (PASMC), such as hyperproliferation, resistance to apoptosis, and cancer theory, have been proposed and widely studied. Here, we tried to summarize the studies, concentrating on the role of PASMC in the development of PH, feasible molecular basis to intervene, and potential treatment to PH.

Expression of ApoA5 and its function in the right ventricular failing and remodeling secondary to pulmonary hypertension

Right heart failure and right ventricular (RV) remodeling were the main reason for mortality of pulmonary hypertension (PH) patients. Apolipoprotein AV (ApoA5) is a key regulator of plasma triglyceride and have multifunction in several target organs. We detected decreased ApoA5 in serum of patients with PH and both in serum and RV of monocrotaline-induced PH model. Exogenously, overexpression ApoA5 by adenovirus showed protective effects on RV failure and RV fibrosis secondary to PH. In addition, in vitro experiments showed ApoA5 attenuated the activation of fibroblast induced by transforming growth factor β1 and synthesis and secretion of extracellular matrix by inhibiting focal adhesion kinase-c-Jun N-terminal kinase-Smad3 pathway. Finally, we suggest that ApoA5 may potentially be a pivotal target for RV failure and fibrosis secondary of PH.

Sodium Tanshinone II Sulfonate A Ameliorates Hypoxia-Induced Pulmonary Hypertension

Background

Pulmonary hypertension (PH) remains a prevalent disease globally. Sodium tanshinone II sulfonate A (STS) has been used in clinical treatment of PH.

Aims

The aim of the present study was to investigate the effect of sodium STS treatment on hypoxia-induced PH and related mechanisms.

Methods

Male Sprague-Dawley rats were housed in a hypoxic chamber with an oxygen concentration of 10 ± 1% for 8 h a day over 21 days. Rats were treated with either STS (low-dose: 10 mg/kg or high-dose: 30 mg/kg) or LY294002 (which is an inhibitor of PI3K). Pulmonary arterial pressure (PAP) was measured, right ventricular hypertrophy parameters were monitored, lung edema parameters were measured, and pathological changes were observed by hematoxylin-eosin (HE) staining. Protein expressions of apoptosis, and PI3K/AKT/mTOR/autophagy pathways in rat lung tissue were examined by western blot. Levels of the pro-inflammatory factors IL-6, IL-8, TNF-α in lung tissues of rats were measured using an enzyme linked immunosorbent assay (ELISA).

Results

Results of our study demonstrate that persistent exposure to hypoxic conditions increased PAP, right ventricular hypertrophy, lung edema, parameters of lung vascular proliferation and decreased the ratio of Bax/Bcl-2. Furthermore, hypoxic conditions activated the PI3K/Akt/mTOR pathway, inhibited autophagy, and elevated abundance of inflammatory factors in rat lung tissue. Treatment with STS resulted in a dose-dependent decrease in PAP, right ventricular hypertrophy, lung edema, lung vascular proliferation and reversed hypoxia induced lung tissue protein expression and pro-inflammatory factors in rat lung tissue. In addition, hypoxia-induced increases in PAP, cardiac hypertrophy, and lung expression of the proteins PI3K/Akt/mTOR/autophagy pathway were partially reversed by treatment with LY294002.

Conclusions

STS alleviates hypoxia-induced PH by promoting apoptosis, inhibiting PI3K/AKT/mTOR pathway, up-regulating autophagy, and inhibiting inflammatory responses.

Pulmonary arterial hypertension: Cellular and molecular changes in the lung

The range of cell types identified in the pathogenesis of pulmonary arterial hypertension (PAH) has expanded substantially since the first pathological descriptions of this disease. This, in turn, has provided needed clarity on the gamut of molecular mechanisms that regulate vascular remodeling and promote characteristic cardiopulmonary hemodynamic changes that define PAH clinically. Insight derived from these scientific advances suggest that the PAH arteriopathy is due to the convergence of numerous molecular mechanisms driving cornerstone endophenotypes, such as plexigenic, hypertrophic, and fibrotic histopathological changes. Interestingly, while some endophenotypes are observed commonly in multiple cell types, such as dysregulated metabolism, other events such as endothelial-mesenchymal transition are cell type-specific. Integrating data from classical PAH vascular cell types with fresh information in pericytes, adventitial fibroblasts, and other PAH contributors recognized more recently has enriched the field with deeper understanding on the molecular basis of this disease. This added complexity, however, also serves as the basis for utilizing novel analytical strategies that emphasize functional signaling pathways when extracting information from big datasets. With these concepts as the backdrop, the current work offers a concise summary of cellular and molecular changes in the lung that drive PAH and may, thus, be important for discovering novel therapeutic targets or applications to clarify PAH onset and disease trajectory.

Identification of Key Players Involved in CoCl2 Hypoxia Induced Pulmonary Artery Hypertension in vitro

Background

The proliferation of human pulmonary artery smooth muscle cells (HPASMCs) induced by hypoxia was considered as the main cause of pulmonary arterial hypertension (PAH). This study aimed to explore potential genes and long non-coding RNAs (lncRNAs) involved in the mechanism of hypoxia-induced PAH.

Methods

CoCl₂ was utilized to induce hypoxia in HPASMCs, and then cell proliferation, apoptosis, and expression of hypoxia-inducible factors (HIF)-1α were determined. Meanwhile, the RNA isolated from CoCl₂-treated cells and control cells were sequenced and differentially expressed genes/lncRNA (DEGs/DELs) were screened, followed by protein-protein interaction (PPI) construction, functional enrichment analyses, and lncRNA-target prediction. Finally, the expression of key genes and lncRNAs were validated using quantitative real-time PCR and western blotting.

Results

CoCl₂ treatment could significantly increase the expression of HIF-1α and the proliferation of HPASMCs. A total of 360 DEGs and 57 DELs were identified between CoCl₂ treated and control cells. Functional enrichment analysis showed that up-regulated DEGs and DELs’ targets, including LDHA, PFKP, and VEGFA, were significantly enriched in biological processes related to hypoxia or oxygen levels, and the downregulated DEGs and DELs’ targets were significantly enriched in extracellular-matrix-related biological processes. In addition, LDHA, PFKP, and VEGFA exhibited a strong relationship with miR-100HG and TSPEAR-AS2 in lncRNA-target network. The protein level of LDHA, PFKP, and VEGFA were all increased.

Conclusion

LDHA, PFKP, VEGFA, and lncRNA miR-100HG and TSPEAR-AS2 probably played crucial roles in the pathogenesis of CoCl₂ hypoxia-induced-HAP, which might serve as promising therapeutic targets for PAH.

Epigenetic Metabolic Reprogramming of Right Ventricular Fibroblasts in Pulmonary Arterial Hypertension: A Pyruvate Dehydrogenase Kinase-Dependent Shift in Mitochondrial Metabolism Promotes Right Ventricular Fibrosis

RATIONALE

Right ventricular (RV) fibrosis in pulmonary arterial hypertension contributes to RV failure. While RV fibrosis reflects changes in the function of resident RV fibroblasts (RVfib), these cells are understudied.

OBJECTIVE

Examine the role of mitochondrial metabolism of RVfib in RV fibrosis in human and experimental pulmonary arterial hypertension.

METHODS AND RESULTS

Male Sprague-Dawley rats received monocrotaline (MCT; 60 mg/kg) or saline. Drinking water containing no supplement or the PDK (pyruvate dehydrogenase kinase) inhibitor dichloroacetate was started 7 days post-MCT. At week 4, treadmill testing, echocardiography, and right heart catheterization were performed. The effects of PDK activation on mitochondrial dynamics and metabolism, RVfib proliferation, and collagen production were studied in RVfib in cell culture. Epigenetic mechanisms for persistence of the profibrotic RVfib phenotype in culture were evaluated. PDK expression was also studied in the RVfib of patients with decompensated RV failure (n=11) versus control (n=7). MCT rats developed pulmonary arterial hypertension, RV fibrosis, and RV failure. MCT-RVfib (but not left ventricular fibroblasts) displayed excess mitochondrial fission and had increased expression of PDK isoforms 1 and 3 that persisted for >5 passages in culture. PDK-mediated decreases in pyruvate dehydrogenase activity and oxygen consumption rate were reversed by dichloroacetate (in RVfib and in vivo) or siRNA targeting PDK 1 and 3 (in RVfib). These interventions restored mitochondrial superoxide and hydrogen peroxide production and inactivated HIF (hypoxia-inducible factor)-1α, which was pathologically activated in normoxic MCT-RVfib. Redox-mediated HIF-1α inactivation also decreased the expression of TGF-β1 (transforming growth factor-beta-1) and CTGF (connective tissue growth factor), reduced fibroblast proliferation, and decreased collagen production. HIF-1α activation in MCT-RVfib reflected increased DNMT (DNA methyltransferase) 1 expression, which was associated with a decrease in its regulatory microRNA, miR-148b-3p. In MCT rats, dichloroacetate, at therapeutic levels in the RV, reduced phospho-pyruvate dehydrogenase expression, RV fibrosis, and hypertrophy and improved RV function. In patients with pulmonary arterial hypertension and RV failure, RVfib had increased PDK1 expression.

CONCLUSIONS

MCT-RVfib manifest a DNMT1-HIF-1α-PDK-mediated, chamber-specific, metabolic memory that promotes collagen production and RV fibrosis. This epigenetic mitochondrial-metabolic pathway is a potential antifibrotic therapeutic target.

Inhibition of Anaplerosis Attenuated Vascular Proliferation in Pulmonary Arterial Hypertension

Vascular remodeling is considered a key event in the pathogenesis of pulmonary arterial hypertension (PAH). However, mechanisms of gaining the proliferative phenotype by pulmonary vascular cells are still unresolved. Due to well-established pyruvate dehydrogenase (PDH) deficiency in PAH pathogenesis, we hypothesized that the activation of another branch of pyruvate metabolism, anaplerosis, via pyruvate carboxylase (PC) could be a key contributor to the metabolic reprogramming of the vasculature. In sugen/hypoxic PAH rats, vascular proliferation was found to be accompanied by increased activation of Akt signaling, which upregulated membrane Glut4 translocation and caused upregulation of hexokinase and pyruvate kinase-2, and an overall increase in the glycolytic flux. Decreased PDH activity and upregulation of PC shuttled more pyruvate to oxaloacetate. This results in the anaplerotic reprogramming of lung vascular cells and their subsequent proliferation. Treatment of sugen/hypoxia rats with the PC inhibitor, phenylacetic acid 20 mg/kg, starting after one week from disease induction, significantly attenuated right ventricular systolic pressure, Fulton index, and pulmonary vascular cell proliferation. PC inhibition reduced the glycolytic shift by attenuating Akt-signaling, glycolysis, and restored mitochondrial pyruvate oxidation. Our findings suggest that targeting PC mediated anaplerosis is a potential therapeutic intervention for the resolution of vascular remodeling in PAH.

Platelet glycolytic metabolism correlates with hemodynamic severity in pulmonary arterial hypertension

Group 1 pulmonary hypertension (PH), i.e., pulmonary arterial hypertension (PAH), is associated with a metabolic shift favoring glycolysis in cells comprising the lung vasculature as well as skeletal muscle and right heart. We sought to determine whether this metabolic switch is also detectable in circulating platelets from PAH patients. We used Seahorse Extracellular Flux to measure bioenergetics in platelets isolated from group 1 PH (PAH), group 2 PH, patients with dyspnea and normal pulmonary artery pressures, and healthy controls. We show that platelets from group 1 PH patients exhibit enhanced basal glycolysis and lower glycolytic reserve compared with platelets from healthy controls but do not differ from platelets of group 2 PH or dyspnea patients without PH. Although we were unable to identify a glycolytic phenotype unique to platelets from PAH patients, we found that platelet glycolytic metabolism correlated with hemodynamic severity only in group 1 PH patients, supporting the known link between PAH pathology and altered glycolytic metabolism and extending this association to ex vivo platelets. Pulmonary artery pressure and pulmonary vascular resistance in patients with group 1 PH were directly associated with basal platelet glycolysis and inversely associated with maximal and reserve glycolysis, suggesting that PAH progression reduces the capacity for glycolysis even while demanding an increase in glycolytic metabolism. Therefore, platelets may provide an easy-to-harvest, real-time window into the metabolic shift occurring in the lung vasculature and represent a useful surrogate for interrogating the glycolytic shift central to PAH pathology.

Plasma metabolomic profile in chronic thromboembolic pulmonary hypertension

We aimed to characterize the plasma metabolome of chronic thromboembolic pulmonary hypertension patients using a high-throughput unbiased omics approach. We collected fasting plasma from a peripheral vein in 33 operable chronic thromboembolic pulmonary hypertension patients, 31 healthy controls, and 21 idiopathic pulmonary arterial hypertension patients matched for age, gender, and body mass index. Metabolomic analysis was performed using an untargeted approach (Metabolon Inc. Durham, NC). Of the total of 862 metabolites identified, 362 were different in chronic thromboembolic pulmonary hypertension compared to controls: 178 were higher and 184 were lower. Compared to idiopathic pulmonary arterial hypertension, 147 metabolites were different in chronic thromboembolic pulmonary hypertension: 45 were higher and 102 were lower. The plasma metabolome allowed us to distinguish subjects with chronic thromboembolic pulmonary hypertension and healthy controls with a predictive accuracy of 89%, and chronic thromboembolic pulmonary hypertension versus idiopathic pulmonary arterial hypertension with 80% accuracy. Compared to idiopathic pulmonary arterial hypertension and healthy controls, chronic thromboembolic pulmonary hypertension patients had higher fatty acids and glycerol; while acyl cholines and lysophospholipids were lower. Compared to healthy controls, both idiopathic pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension patients had increased acyl carnitines, beta-hydroxybutyrate, amino sugars and modified amino acids and nucleosides. The plasma global metabolomic profile of chronic thromboembolic pulmonary hypertension suggests aberrant lipid metabolism characterized by increased lipolysis, fatty acid oxidation, and ketogenesis, concomitant with reduced acyl choline and phospholipid moieties. Future research should investigate the pathogenetic and therapeutic potential of modulating lipid metabolism in chronic thromboembolic pulmonary hypertension.

Blood-based bioenergetics: An emerging translational and clinical tool

Accumulating studies demonstrate that mitochondrial genetics and function are central to determining the susceptibility to, and prognosis of numerous diseases across all organ systems. Despite this recognition, mitochondrial function remains poorly characterized in humans primarily due to the invasiveness of obtaining viable tissue for mitochondrial studies. Recent studies have begun to test the hypothesis that circulating blood cells, which can be obtained by minimally invasive methodology, can be utilized as a biomarker of systemic bioenergetic function in human populations. Here we present the available methodologies for assessing blood cell bioenergetics and review studies that have applied these techniques to healthy and disease populations. We focus on the validation of this methodology in healthy subjects, as well as studies testing whether blood cell bioenergetics are altered in disease, correlate with clinical parameters, and compare with other methodology for assessing human mitochondrial function. Finally, we present the challenges and goals for the development of this emerging approach into a tool for translational research and personalized medicine.

Metabolomics reveals metabolite changes of patients with pulmonary arterial hypertension in China

The specific mechanism of pulmonary arterial hypertension (PAH) remains elusive. The present study aimed to explore the underlying mechanism of PAH through the identity of novel biomarkers for PAH using metabolomics approach. Serum samples from 40 patients with idiopathic PAH (IPAH), 20 patients with congenital heart disease-associated PAH (CHD-PAH) and 20 healthy controls were collected and analysed by ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UPLC-HRMS). Orthogonal partial least square-discriminate analysis (OPLS-DA) was applied to screen potential biomarkers. These results were validated in monocrotaline (MCT)-induced PAH rat model. The OPLS-DA model was successful in screening distinct metabolite signatures which distinguished IPAH and CHD-PAH patients from healthy controls, respectively (26 and 15 metabolites). Unbiased analysis from OPLS-DA identified 31 metabolites from PAH patients which were differentially regulated compared to the healthy controls. Our analysis showed dysregulation of the different metabolic pathways, including lipid metabolism, glucose metabolism, amino acid metabolism and phospholipid metabolism pathways in PAH patients compared to their healthy counterpart. Among these metabolites from dysregulated metabolic pathways, a panel of metabolites from lipid metabolism and fatty acid oxidation (lysophosphatidylcholine, phosphatidylcholine, perillic acid, palmitoleic acid, N-acetylcholine-d-sphingomyelin, oleic acid, palmitic acid and 2-Octenoylcarnitine metabolites) were found to have a close association with PAH. The results from the analysis of both real-time quantitative PCR and Western blot showed that expression of LDHA, CD36, FASN, PDK1 GLUT1 and CPT-1 in right heart/lung were significantly up-regulated in MCT group than the control group.

Panax ginseng C.A. Meyer (Rg3) Ameliorates Gastric Precancerous Lesions in Atp4a-/- Mice via Inhibition of Glycolysis through PI3K/AKT/miRNA-21 Pathway

Gastric cancer, one of the most common types of cancers, develops over a series of consecutive histopathological stages. As such, the analysis and research of the gastric precancerous lesions (GPLs) play an important role in preventing the occurrence of gastric cancer. Ginsenoside Rg3 (Rg3), an herbal medicine, plays an important role in the prevention and treatment of various cancers. Studies have demonstrated a correlation between glycolysis and gastric cancer progression. Herein, the aim of the present study was to clarify the potential role for glycolysis pathogenesis in Rg3-treated GPL in Atp4a^−/− mice. The GPL mice model showed chronic gastritis, intestinal metaplasia, and more atypical hyperplasia in gastric mucosa. According to the results of HE and AB-PAS staining, it could be confirmed that GPL mice were obviously reversed by Rg3. Additionally, the increased protein levels of PI3K, AKT, mTOR, HIF-1α, LDHA, and HK-II, which are crucial factors for evaluating GPL in the aspect of glycolysis pathogenesis in the model group, were downregulated by Rg3. Meanwhile, the miRNA-21 expression was decreased and upregulated by Rg3. Furthermore, the increased gene levels of Bcl-2 and caspase-3 were attenuated in Rg3-treated GPL mice. In conclusion, the findings of this study imply that abnormal glycolysis in GPL mice was relieved by Rg3 via regulation of the expressions of PI3K, AKT, mTOR, HIF-1α, LDHA, HK-II, and miRNA-21. Rg3 is an effective supplement for GPL treatment and can be harnessed to inhibit proliferation and induce apoptosis of GPL cells.