Pulmonary arterial hypertension (PAH) is characterized by obliterative vascular remodeling in the lungs and progressive increases of pulmonary vascular resistance that cause right heart failure and premature death. Although great strides have been made in treatment of PAH, current therapies fail to reverse the disease and only resulted in a modest improvement in the morbidity and mortality. Employing novel mouse model with Tie2Cre-mediated deletion of Egln1 [encoding hypoxia-inducible factor (HIF) prolyl hydroxylase 2, PHD2] (Egln1Tie2 mice) in endothelial cells (ECs) and hematopoietic cells, we observed severe PAH as evident by markedly elevated right ventricular systolic pressure (RVSP) and severe vascular remodeling including pulmonary vascular occlusion and plexiform-like lesions as seen in patients with idiopathic PAH (IPAH). This unprecedented pulmonary vascular remodeling and hypertensive phenotypes were inhibited in the double mutant mice with genetic deletions of both Egln1 and HIF2?. Our Supporting Data also show that pharmacological inhibition of HIF-2? attenuated the PAH phenotype in Egln1Tie2 mice. Intriguingly, WT bone marrow transplantation resulted in decreased RVSP and RV hypertrophy in Egln1Tie2 chimeric mice, indicating that the bone marrow abnormalities contribute to the severity of PAH in Egln1Tie2 mice. Thus, we hypothesize that PHD2 deficiency in ECs and hematopoietic cells plays a synergistic role in the pathogenesis of obliterative vascular remodeling and severe PAH via activation of HIF-2? signaling in ECs and HIF-1? signaling in hematopoietic cells. The proposed studies will address the following Specific Aims.
In Aim 1, we will determine whether severe PAH exhibited in Egln1Tie2 mice recapitulates the pathophysiology of PAH in IPAH patients and define the role of activated HIF-2? signaling secondary to PHD2 deficiency in mediating severe PAH.
In Aim 2, we will address the synergistic role of PHD2 deficiency-activated HIF signalings in pulmonary vascular ECs and hematopoietic cells in the mechanisms of severe PAH. Studies in Aim 3 will delineate the molecular basis of severe pulmonary vascular remodeling and resultant PAH seen in Egln1Tie2 mice and explore the translational potential of selectively targeting HIF-2? signaling for the prevention and treatment of PAH in patients. Given the marked similarity of severe PAH seen in Egln1Tie2 mice and in IPAH patients, we expect that the proposed studies have significant translational potential by identifying druggable targets and exploring novel pharmacological agents that can pharmacologically inhibit/reverse vascular remodeling for the prevention and treatment of severe PAH in patients. 1

Public Health Relevance

The overall objective of the proposed studies is to determine the role of PHD2 deficiency in the mechanisms of obliterative pulmonary vascular remodeling and severe PAH and thereby provide novel therapeutic approaches for treatment of PAH to reverse vascular remodeling and promote survival.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL133951-04
Application #
9692764
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Xiao, Lei
Project Start
2018-07-01
Project End
2020-06-30
Budget Start
2019-07-01
Budget End
2020-06-30
Support Year
4
Fiscal Year
2019
Total Cost
Indirect Cost
Name
Children's Memorial Hospital (Chicago)
Department
Type
DUNS #
074438755
City
Chicago
State
IL
Country
United States
Zip Code
60611
Singla, Sunit; Machado, Roberto F (2018) Death of the Endothelium in Sepsis: Understanding the Crime Scene. Am J Respir Cell Mol Biol 59:3-4
Dai, Zhiyu; Zhu, Maggie M; Peng, Yi et al. (2018) Endothelial and Smooth Muscle Cell Interaction via FoxM1 Signaling Mediates Vascular Remodeling and Pulmonary Hypertension. Am J Respir Crit Care Med 198:788-802
Sysol, Justin R; Chen, Jiwang; Singla, Sunit et al. (2018) Micro-RNA-1 is decreased by hypoxia and contributes to the development of pulmonary vascular remodeling via regulation of sphingosine kinase 1. Am J Physiol Lung Cell Mol Physiol 314:L461-L472
DeLalio, Leon J; Keller, Alexander S; Chen, Jiwang et al. (2018) Interaction Between Pannexin 1 and Caveolin-1 in Smooth Muscle Can Regulate Blood Pressure. Arterioscler Thromb Vasc Biol 38:2065-2078
Brittain, Evan L; Thennapan, Thennapan; Maron, Bradley A et al. (2018) Update in Pulmonary Vascular Disease 2016 and 2017. Am J Respir Crit Care Med 198:13-23
Duarte, Julio D; Kansal, Mayank; Desai, Ankit A et al. (2018) Endothelial nitric oxide synthase genotype is associated with pulmonary hypertension severity in left heart failure patients. Pulm Circ 8:2045894018773049
Du, Xueke; Jiang, Chunling; Lv, Yang et al. (2017) Isoflurane promotes phagocytosis of apoptotic neutrophils through AMPK-mediated ADAM17/Mer signaling. PLoS One 12:e0180213
Singla, Sunit; Chen, Jiwang; Sethuraman, Shruthi et al. (2017) Loss of lung WWOX expression causes neutrophilic inflammation. Am J Physiol Lung Cell Mol Physiol 312:L903-L911
Evans, Colin E; Zhao, You-Yang (2017) Impact of thrombosis on pulmonary endothelial injury and repair following sepsis. Am J Physiol Lung Cell Mol Physiol 312:L441-L451
Soni, Dheeraj; Regmi, Sushil C; Wang, Dong-Mei et al. (2017) Pyk2 phosphorylation of VE-PTP downstream of STIM1-induced Ca2+ entry regulates disassembly of adherens junctions. Am J Physiol Lung Cell Mol Physiol 312:L1003-L1017

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