Persistent pulmonary hypertension of the newborn (PPHN) is a condition that results from failure of pulmonary vasodilation to occur at birth. The affected infants are hypoxemic and have increased risks of mortality and long-term disabilities. Studies in a fetal lamb model of PPHN, induced by prenatal ductal constriction demonstrated a decrease in NO release and increase in oxidative stress in pulmonary arteries. Activation of NADPH oxidase and uncoupled activity of endothelial nitric oxide synthase (eNOS) are sources of superoxide (O2?-) in the pulmonary arteries in PPHN. Mitochondrial oxygen consumption is an important source of O2?- generation in vascular cells. Increase in O2 availability and oxidative phosphorylation at birth may lead to increased reactive oxygen species (ROS) in mitochondria. However, the contribution of mitochondrial ROS to oxidative stress in PPHN is unknown. Exposure to ATP, a NOS agonist, and postnatal oxygen tension stimulate the association of eNOS with the mitochondrial outer membrane protein, porin in normal fetal lamb pulmonary artery endothelial cells (PAEC). Targeted NO release in this location regulates the rate of oxidative phosphorylation to decrease O2?- production in normal fetal PAEC. The expression of manganese superoxide dismutase (MnSOD) is also decreased in PPHN. We propose to investigate the novel hypothesis that decreased targeting of eNOS to mitochondrial outer membrane and decreased expression of MnSOD lead to excess generation and decreased quenching of mitochondrial O2?-. The mitochondrial O2?- in turn impairs pulmonary vasodilation at birth. The broad specific aims of the proposed studies are to (1) Investigate the alterations in eNOS-mitochondrial interactions and MnSOD expression in PPHN and its effect on O2 consumption, NO and O2?- levels during postnatal transition of PAEC, (2) Investigate the mechanism of altered eNOS targeting to mitochondria in PPHN and (3) investigate the role of mitochondrial oxidative stress in the impaired pulmonary vasodilation and oxygenation during birth-related transition in PPHN. Studies will be done in PAEC and pulmonary arteries harvested from lambs with prenatal ligation of ductus arteriosus (PPHN) and in sham ligation controls. Studies will be also done in intact fetal lambs with or without PPHN delivered at term to investigate the role of mitochondrial O2?- in the transition of pulmonary circulation and oxygenation at birth. These studies will identify an important new source of oxidative stress in PPHN. These observation may lead to new targeted therapies to improve vasodilation and oxygenation in PPHN.

Public Health Relevance

An increase in blood flow to the lung occurs at birth to help establish gas exchange by the lung during postnatal life. Failure of this adaptation results in persistent pulmonary pulmonary hypertension in the newborn infant (PPHN), associated with severe hypoxemia and increased risk of death and disability. The proposed studies will investigate the mechanisms and potential new therapies for this disease.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL057268-11
Application #
8449312
Study Section
Respiratory Integrative Biology and Translational Research Study Section (RIBT)
Program Officer
Lin, Sara
Project Start
1998-05-01
Project End
2014-03-31
Budget Start
2013-04-01
Budget End
2014-03-31
Support Year
11
Fiscal Year
2013
Total Cost
$250,201
Indirect Cost
$80,576
Name
Medical College of Wisconsin
Department
Pediatrics
Type
Schools of Medicine
DUNS #
937639060
City
Milwaukee
State
WI
Country
United States
Zip Code
53226
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Konduri, Girija G; Afolayan, Adeleye J; Eis, Annie et al. (2015) Interaction of endothelial nitric oxide synthase with mitochondria regulates oxidative stress and function in fetal pulmonary artery endothelial cells. Am J Physiol Lung Cell Mol Physiol 309:L1009-17
Afolayan, Adeleye J; Teng, Ru-Jeng; Eis, Annie et al. (2014) Inducible HSP70 regulates superoxide dismutase-2 and mitochondrial oxidative stress in the endothelial cells from developing lungs. Am J Physiol Lung Cell Mol Physiol 306:L351-60
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