Mitochondria as a primary determinant of angiogenic modality in pulmonary arterial hypertension.

Impaired pulmonary angiogenesis plays a pivotal role in the progression of pulmonary arterial hypertension (PAH) and patient mortality, yet the molecular mechanisms driving this process remain enigmatic. Our study uncovered a striking connection between mitochondrial dysfunction (MD), caused by a humanized mutation in the NFU1 gene, and severely disrupted pulmonary angiogenesis in adult lungs. Restoring the bioavailability of the NFU1 downstream target, lipoic acid (LA), alleviated MD and angiogenic deficiency and rescued the progressive PAH phenotype in the NFU1G206C model.

Skeletal Muscle SIRT3 Deficiency Contributes to Pulmonary Vascular Remodeling in Pulmonary Hypertension Due to Heart Failure With Preserved Ejection Fraction.

Background: Pulmonary hypertension (PH) is a major complication linked to adverse outcomes in heart failure with preserved ejection fraction (HFpEF), yet no specific therapies exist for PH associated with HFpEF (PH-HFpEF). We have recently reported on the role of skeletal muscle SIRT3 (sirtuin-3) in modulation of PH-HFpEF, suggesting a novel endocrine signaling pathway for skeletal muscle modulation of pulmonary vascular remodeling.

Methods: Using skeletal muscle-specific knockout mice () and mass spectrometry-based comparative secretome analysis, we attempted to define the processes by which skeletal muscle SIRT3 defects affect pulmonary vascular health in PH-HFpEF.

Cross-talk between TSC2 and the extracellular matrix controls pulmonary vascular proliferation and pulmonary hypertension.

Increased proliferation and survival of cells in small pulmonary arteries (PAs) drive pulmonary arterial hypertension (PAH). Because cell growth mediated by the mTOR-containing mTORC1 complex is inhibited by tuberous sclerosis complex 2 (TSC2), we investigated the role of this GTPase-activating protein in PAH pathology. TSC2 abundance was decreased in remodeled small PAs and PA vascular smooth muscle cells (PAVSMCs) from patients with PAH or from rodent pulmonary hypertension (PH) models, as well as PAVSMCs maintained on substrates that reproduced pathology-induced stiffness.

Akt-Dependent Glycolysis-Driven Lipogenesis Supports Proliferation and Survival of Human Pulmonary Arterial Smooth Muscle Cells in Pulmonary Hypertension.

Hyper-proliferation of pulmonary arterial vascular smooth muscle cells (PAVSMC) is an important pathological component of pulmonary vascular remodeling in pulmonary arterial hypertension (PAH). Lipogenesis is linked to numerous proliferative diseases, but its role in PAVSMC proliferation in PAH remains to be elucidated. We found that early-passage human PAH PAVSMC had significant up-regulation of key fatty acids synthesis enzymes ATP-citrate lyase (ACLY), acetyl-CoA carboxylase (ACC), and fatty acid synthase (FASN), and increased unstimulated proliferation compared to control human PAVSMC.

Noncanonical HIPPO/MST Signaling via BUB3 and FOXO Drives Pulmonary Vascular Cell Growth and Survival.

Rationale: The MSTs (mammalian Ste20-like kinases) 1/2 are members of the HIPPO pathway that act as growth suppressors in adult proliferative diseases. Pulmonary arterial hypertension (PAH) manifests by increased proliferation and survival of pulmonary vascular cells in small PAs, pulmonary vascular remodeling, and the rise of pulmonary arterial pressure. The role of MST1/2 in PAH is currently unknown.

Metabolic Syndrome Mediates ROS-miR-193b-NFYA-Dependent Downregulation of Soluble Guanylate Cyclase and Contributes to Exercise-Induced Pulmonary Hypertension in Heart Failure With Preserved Ejection Fraction.

Background: Many patients with heart failure with preserved ejection fraction have metabolic syndrome and develop exercise-induced pulmonary hypertension (EIPH). Increases in pulmonary vascular resistance in patients with heart failure with preserved ejection fraction portend a poor prognosis; this phenotype is referred to as combined precapillary and postcapillary pulmonary hypertension (CpcPH). Therapeutic trials for EIPH and CpcPH have been disappointing, suggesting the need for strategies that target upstream mechanisms of disease.

Wilson Disease: Intersecting DNA Methylation and Histone Acetylation Regulation of Gene Expression in a Mouse Model of Hepatic Copper Accumulation.

Background & Aims: The pathogenesis of Wilson disease (WD) involves hepatic and brain copper accumulation resulting from pathogenic variants affecting the ATP7B gene and downstream epigenetic and metabolic mechanisms. Prior methylome investigations in human WD liver and blood and in the Jackson Laboratory (Bar Harbor, ME) C3He-Atp7b/J (tx-j) WD mouse model revealed an epigenetic signature of WD, including changes in histone deacetylase (HDAC) 5. We tested the hypothesis that histone acetylation is altered with respect to copper overload and aberrant DNA methylation in WD.

Functional NMDA receptors are expressed by human pulmonary artery smooth muscle cells.

N-methyl-D-aspartate (NMDA) receptors are widely expressed in the central nervous system. However, their presence and function at extraneuronal sites is less well characterized. In the present study, we examined the expression of NMDA receptor subunit mRNA and protein in human pulmonary artery (HPA) by quantitative polymerase chain reaction (PCR), immunohistochemistry and immunoblotting.

Treatment With Treprostinil and Metformin Normalizes Hyperglycemia and Improves Cardiac Function in Pulmonary Hypertension Associated With Heart Failure With Preserved Ejection Fraction.

Objective: Pulmonary hypertension (PH) due to left heart disease (group 2), especially in the setting of heart failure with preserved ejection fraction (HFpEF), is the most common cause of PH worldwide; however, at present, there is no proven effective therapy available for its treatment. PH-HFpEF is associated with insulin resistance and features of metabolic syndrome. The stable prostacyclin analog, treprostinil, is an effective and widely used Food and Drug Administration-approved drug for the treatment of pulmonary arterial hypertension.

Differential effects of integrin-linked kinase inhibitor Cpd22 on severe pulmonary hypertension in male and female rats.

Pulmonary arterial hypertension (PAH) is a progressive fatal disease with no cure. Inhibition of integrin-linked kinase (ILK) reverses experimental pulmonary hypertension (PH) in male mice, but its effect on severe experimental PH in either male or female animals is unknown. We examined effects of ILK inhibitor Cpd22 on rats with SU5416/hypoxia-induced PH; treatment was performed at six to eight weeks after PH initiation.

Distinct plasma gradients of microRNA-204 in the pulmonary circulation of patients suffering from WHO Groups I and II pulmonary hypertension.

Pulmonary hypertension (PH), a heterogeneous vascular disease, consists of subtypes with overlapping clinical phenotypes. MicroRNAs, small non-coding RNAs that negatively regulate gene expression, have emerged as regulators of PH pathogenesis. The muscle-specific micro RNA (miR)-204 is known to be depleted in diseased pulmonary artery smooth muscle cells (PASMCs), furthering proliferation and promoting PH.

Inhibitory Antibodies against Activin A and TGF-β Reduce Self-Supported, but Not Soluble Factors-Induced Growth of Human Pulmonary Arterial Vascular Smooth Muscle Cells in Pulmonary Arterial Hypertension.

Increased growth and proliferation of distal pulmonary artery vascular smooth muscle cells (PAVSMC) is an important pathological component of pulmonary arterial hypertension (PAH). Transforming Growth Factor-β (TGF-β) superfamily plays a critical role in PAH, but relative impacts of self-secreted Activin A, Gremlin1, and TGF-β on PAH PAVSMC growth and proliferation are not studied. Here we report that hyper-proliferative human PAH PAVSMC have elevated secretion of TGF-β1 and, to a lesser extent, Activin A, but not Gremlin 1, and significantly reduced Ser-Smad2 and Ser-Smad3 phosphorylation compared to controls.

Endothelial Nox1 oxidase assembly in human pulmonary arterial hypertension; driver of Gremlin1-mediated proliferation.

Pulmonary arterial hypertension (PAH) is a rapidly degenerating and devastating disease of increased pulmonary vessel resistance leading to right heart failure. Palliative modalities remain limited despite recent endeavors to investigate the mechanisms underlying increased pulmonary vascular resistance (PVR), i.e.

Automated Measurement of Blood Vessels in Tissues from Microscopy Images.

The quantification of tunica media thickness in histological cross sections is a ubiquitous exercise in cardiopulmonary research, yet the methods for quantifying medial wall thickness have never been rigorously examined with modern image analysis tools. As a result, inaccurate and cumbersome manual measurements of discrete wall regions along the vessel periphery have become common practice for wall thickness quantification. The aim of this study is to introduce, validate, and facilitate the use of an improved method for medial wall thickness quantification.

HIPPO-Integrin-linked Kinase Cross-Talk Controls Self-Sustaining Proliferation and Survival in Pulmonary Hypertension.

Rationale: Enhanced proliferation and impaired apoptosis of pulmonary arterial vascular smooth muscle cells (PAVSMCs) are key pathophysiologic components of pulmonary vascular remodeling in pulmonary arterial hypertension (PAH).

Objectives: To determine the role and therapeutic relevance of HIPPO signaling in PAVSMC proliferation/apoptosis imbalance in PAH.

Methods: Primary distal PAVSMCs, lung tissue sections from unused donor (control) and idiopathic PAH lungs, and rat and mouse models of SU5416/hypoxia-induced pulmonary hypertension (PH) were used.

SIRT3-AMP-Activated Protein Kinase Activation by Nitrite and Metformin Improves Hyperglycemia and Normalizes Pulmonary Hypertension Associated With Heart Failure With Preserved Ejection Fraction.

Background: Pulmonary hypertension associated with heart failure with preserved ejection fraction (PH-HFpEF) is an increasingly recognized clinical complication of metabolic syndrome. No adequate animal model of PH-HFpEF is available, and no effective therapies have been identified to date. A recent study suggested that dietary nitrate improves insulin resistance in endothelial nitric oxide synthase null mice, and multiple studies have reported that both nitrate and its active metabolite, nitrite, have therapeutic activity in preclinical models of pulmonary hypertension.

Profiling the role of mammalian target of rapamycin in the vascular smooth muscle metabolome in pulmonary arterial hypertension.

Increased proliferation and resistance to apoptosis of pulmonary arterial vascular smooth muscle cells (PAVSMCs), coupled with metabolic reprogramming, are key components of pulmonary vascular remodeling, a major and currently irreversible pathophysiological feature of pulmonary arterial hypertension (PAH). We recently reported that activation of mammalian target of rapamycin (mTOR) plays a key role in increased energy generation and maintenance of the proliferative, apoptosis-resistant PAVSMC phenotype in human PAH, but the downstream effects of mTOR activation on PAH PAVSMC metabolism are not clear. Using liquid and gas chromatography-based mass spectrometry, we performed pilot metabolomic profiling of human microvascular PAVSMCs from idiopathic-PAH subjects before and after treatment with the selective adenosine triphosphate-competitive mTOR inhibitor PP242 and from nondiseased lungs.

Tumor suppressors TSC1 and TSC2 differentially modulate actin cytoskeleton and motility of mouse embryonic fibroblasts.

TSC1 and TSC2 mutations cause neoplasms in rare disease pulmonary LAM and neuronal pathfinding in hamartoma syndrome TSC. The specific roles of TSC1 and TSC2 in actin remodeling and the modulation of cell motility, however, are not well understood. Previously, we demonstrated that TSC1 and TSC2 regulate the activity of small GTPases RhoA and Rac1, stress fiber formation and cell adhesion in a reciprocal manner.

Folliculin controls lung alveolar enlargement and epithelial cell survival through E-cadherin, LKB1, and AMPK.

Spontaneous pneumothoraces due to lung cyst rupture afflict patients with the rare disease Birt-Hogg-Dubé (BHD) syndrome, which is caused by mutations of the tumor suppressor gene folliculin (FLCN). The underlying mechanism of the lung manifestations in BHD is unclear. We show that BHD lungs exhibit increased alveolar epithelial cell apoptosis and that Flcn deletion in mouse lung epithelium leads to cell apoptosis, alveolar enlargement, and an impairment of both epithelial barrier and overall lung function.

Mammalian target of rapamycin complex 2 (mTORC2) coordinates pulmonary artery smooth muscle cell metabolism, proliferation, and survival in pulmonary arterial hypertension.

Background: Enhanced proliferation, resistance to apoptosis, and metabolic shift to glycolysis of pulmonary arterial vascular smooth muscle cells (PAVSMCs) are key pathophysiological components of pulmonary vascular remodeling in idiopathic pulmonary arterial hypertension (PAH). The role of the distinct mammalian target of rapamycin (mTOR) complexes mTORC1 (mTOR-Raptor) and mTORC2 (mTOR-Rictor) in PAVSMC proliferation and survival in PAH and their therapeutic relevance are unknown.

Methods And Results: Immunohistochemical and immunoblot analyses revealed that mTORC1 and mTORC2 pathways are markedly upregulated in small remodeled pulmonary arteries and isolated distal PAVSMCs from subjects with idiopathic PAH that have increased ATP levels, proliferation, and survival that depend on glycolytic metabolism.

Statins in lymphangioleiomyomatosis. Simvastatin and atorvastatin induce differential effects on tuberous sclerosis complex 2-null cell growth and signaling.

Mutations of the tumor suppressor genes tuberous sclerosis complex (TSC)1 and TSC2 cause pulmonary lymphangioleiomyomatosis (LAM) and tuberous sclerosis (TS). Current rapamycin-based therapies for TS and LAM have a predominantly cytostatic effect, and disease progression resumes with therapy cessation. Evidence of RhoA GTPase activation in LAM-derived and human TSC2-null cells suggests that 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor statins can be used as potential adjuvant agents.

Rapamycin prevents seizures after depletion of STRADA in a rare neurodevelopmental disorder.

A rare neurodevelopmental disorder in the Old Order Mennonite population called PMSE (polyhydramnios, megalencephaly, and symptomatic epilepsy syndrome; also called Pretzel syndrome) is characterized by infantile-onset epilepsy, neurocognitive delay, craniofacial dysmorphism, and histopathological evidence of heterotopic neurons in subcortical white matter and subependymal regions. PMSE is caused by a homozygous deletion of exons 9 to 13 of the LYK5/STRADA gene, which encodes the pseudokinase STRADA, an upstream inhibitor of mammalian target of rapamycin complex 1 (mTORC1). We show that disrupted pathfinding in migrating mouse neural progenitor cells in vitro caused by STRADA depletion is prevented by mTORC1 inhibition with rapamycin or inhibition of its downstream effector p70 S6 kinase (p70S6K) with the drug PF-4708671 (p70S6Ki).

Differential effects of formoterol on thrombin- and PDGF-induced proliferation of human pulmonary arterial vascular smooth muscle cells.

Background: Increased pulmonary arterial vascular smooth muscle (PAVSM) cell proliferation is a key pathophysiological component of pulmonary vascular remodeling in pulmonary arterial hypertension (PH). The long-acting β2-adrenergic receptor (β2AR) agonist formoterol, a racemate comprised of (R,R)- and (S,S)-enantiomers, is commonly used as a vasodilator in chronic obstructive pulmonary disease (COPD). PH, a common complication of COPD, increases patients' morbidity and reduces survival.

Prevention of alveolar destruction and airspace enlargement in a mouse model of pulmonary lymphangioleiomyomatosis (LAM).

Pulmonary lymphangioleiomyomatosis (LAM) is a rare genetic disease characterized by neoplastic growth of atypical smooth muscle-like LAM cells, destruction of lung parenchyma, obstruction of lymphatics, and formation of lung cysts, leading to spontaneous pneumothoraces (lung rupture and collapse) and progressive loss of pulmonary function. The disease is caused by mutational inactivation of the tumor suppressor gene tuberous sclerosis complex 1 (TSC1) or TSC2. By injecting TSC2-null cells into nude mice, we have developed a mouse model of LAM that is characterized by multiple random TSC2-null lung lesions, vascular endothelial growth factor-D expression, lymphangiogenesis, destruction of lung parenchyma, and decreased survival, similar to human LAM.