This is a competitive renewal of our R37 MERIT (2009-2019), which aims to define mechanisms of Pulmonary Arterial Hypertension (PAH). Our work led to new knowledge, shared resources and methods, including a critical advance in harvest and culture of human pulmonary artery endothelial cells (PAEC). We identified loss of nitric oxide (NO) production, and mechanisms: (i) phosphorylation inactivation of endothelial NO synthase (eNOS), and (ii) decreased eNOS substrate arginine (arg) availability related to increased mitochondrial arginase 2 (ARG2). We discovered that high-altitude natives, who avoid high-altitude hypoxic pulmonary hypertension (HAPH), have adaptations that increase arg, NO, and decrease ARG2. In parallel, we found that PAH PAEC have less mitochondrial respiration than control cells, and a shift to aerobic glycolysis. In vivo, lung and cardiac glucose uptake in PAH patients measured by 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) was higher than controls. In preliminary data, patients with the highest FDG uptake have the lowest arg levels and most severe disease, suggesting that arg metabolic fate impacts PAH beyond just the loss of vasodilator NO. We show that mitochondrial arg metabolism is interconnected to bioenergetics, including fuel dependency of tricarboxylic acid cycle (TCA) and mitochondrial respiration. In murine studies, Arg2 knockout (Arg2KO) have greater capacity for mitochondrial respiration and less cardiac glucose uptake than wildtype (WT), and lack the hypoxia-induced increases of pulmonary pressures and erythropoietin (Epo) found in WT. Thus, we hypothesize that mitochondrial arg metabolism via ARG2 is interconnected to abnormalities of TCA cycle and bioenergetics, and promotes pathologic proliferation of PAEC, development of PAH and right ventricular (RV) dysfunction.
Aim 1 identifies disease metabolic mechanisms and pathways that participate in pathologic endothelial functions and PAH pathophysiology. To find pathways associated with PAH, we perform differential expression (RNA, protein, metabolites) and integrative network analyses of PAH and control PAEC, then measure cell bioenergetics and functions after blocking pathways enriched in PAH (Aim1A). PAH patients, dichotomized into low or high cardiac FDG uptake groups, are compared with controls using metabolomic and transcriptomic analyses to uncover pathways in vivo, then followed longitudinally to determine if death, transplant, and/or worsening RV systolic pressure (RVSP) is greater in the high uptake group (Aim1B).
Aim 2 determines if decreasing mitochondrial arg metabolism is protective against hypoxia-associated PH. Metabolomic profiles of high-altitude Amhara, who have high NO, low arginase, and resist HAPH, are compared to their low-altitude counterparts and PAH patients, to identify protective pathways in relation to quantitative traits, such as Epo and RVSP (Aim 2A). In mechanistic studies, we determine if Arg2KO have bioenergetic changes as compared to WT, and if Arg2KO are protected from hypoxia-induced elevations in Epo and pulmonary pressures (Aim 2B). These studies will provide new metabolic understanding of PAH, and offer new potential therapeutic targets.

Public Health Relevance

Pulmonary arterial hypertension (PAH) is a progressive and often lethal disease that disproportionately affects women. In this project, our goal is to discover the cellular metabolic mechanisms underlying the development and progression of PAH so that we can develop new strategies for treatment of patients.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
Project #
Application #
Study Section
Respiratory Integrative Biology and Translational Research Study Section (RIBT)
Program Officer
Xiao, Lei
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Cleveland Clinic Lerner
Other Basic Sciences
Schools of Medicine
United States
Zip Code
Allawzi, Ayed M; Vang, Alexander; Clements, Richard T et al. (2018) Activation of Anoctamin-1 Limits Pulmonary Endothelial Cell Proliferation via p38-Mitogen-activated Protein Kinase-Dependent Apoptosis. Am J Respir Cell Mol Biol 58:658-667
Janocha, Allison J; Comhair, Suzy A A; Basnyat, Buddha et al. (2017) Antioxidant defense and oxidative damage vary widely among high-altitude residents. Am J Hum Biol 29:
Asosingh, Kewal; Wanner, Nicholas; Weiss, Kelly et al. (2017) Bone marrow transplantation prevents right ventricle disease in the caveolin-1-deficient mouse model of pulmonary hypertension. Blood Adv 1:526-534
Hwangbo, Cheol; Lee, Heon-Woo; Kang, Hyeseon et al. (2017) Modulation of Endothelial Bone Morphogenetic Protein Receptor Type 2 Activity by Vascular Endothelial Growth Factor Receptor 3 in Pulmonary Arterial Hypertension. Circulation 135:2288-2298
Cheong, Hoi I; Asosingh, Kewal; Stephens, Olivia R et al. (2016) Hypoxia sensing through ?-adrenergic receptors. JCI Insight 1:e90240
Yuan, Yiyuan; Hakimi, Parvin; Kao, Clara et al. (2016) Reciprocal Changes in Phosphoenolpyruvate Carboxykinase and Pyruvate Kinase with Age Are a Determinant of Aging in Caenorhabditis elegans. J Biol Chem 291:1307-19
Farha, Samar; Hu, Bo; Comhair, Suzy et al. (2016) Mitochondrial Haplogroups and Risk of Pulmonary Arterial Hypertension. PLoS One 11:e0156042
Rose, Jonathan A; Wanner, Nicholas; Cheong, Hoi I et al. (2016) Flow Cytometric Quantification of Peripheral Blood Cell ?-Adrenergic Receptor Density and Urinary Endothelial Cell-Derived Microparticles in Pulmonary Arterial Hypertension. PLoS One 11:e0156940
Roach, Emir C; Park, Margaret M; Tang, W H Wilson et al. (2015) Impaired right ventricular-pulmonary vascular function in myeloproliferative neoplasms. J Heart Lung Transplant 34:390-4
Yu, Jun; Wilson, Jamie; Taylor, Linda et al. (2015) DNA microarray and signal transduction analysis in pulmonary artery smooth muscle cells from heritable and idiopathic pulmonary arterial hypertension subjects. J Cell Biochem 116:386-97

Showing the most recent 10 out of 84 publications