Diminished alveolar complexity and vascular development of the lung is a constant feature of bronchopulmonary dysplasia (BPD). It persists even now that oxygen therapy is used at much lower levels than 1-2 decades ago. The lung develops at low, fetal oxygen concentrations (3-5%), and, in vitro, it develops much better at these levels than in 21%. Endothelial and vascular growth is impaired at these higher oxygen levels. Epithelial and alveolar development, in turn, depend on critical interactions with the developing vasculature. Thus, the distal airways of fetal lung in 21% show much less branching. Angiogenesis is proceeding rapidly in the third trimester of gestation. Hypoxia-inducible factors HIF- 1 and -2 (HIFs) regulate critical growth factors, receptors, kinases, and other proteins in angiogenesis. Oxygen tension is the primary regulator of HIF- 1alpha and -2alpha, the key components of these transcription factors. Knocking down HIF-2 in lung throughout gestation, or in distal lung epithelium during the third trimester, results in oversimplified lung development and respiratory distress in newborn mice. Recently HIF prolyl-4- hydroxylases (P4Hs or PHDs) were found to catalyze O2-dependent degradation of HIFs. Inhibiting P4Hs with oxoglutarate analogs or iron chelators stabilize HIFs, increase VEGF, and cause angiogenesis. HIFspecific P4H inhibitors are being rapidly developed. In trials in cardiovascular medicine, angiogenic therapy with single growth factors has caused formation of dysmorphic or leaky vessels. """"""""Flipping the switch"""""""" of HIFs in the normoxic lung can cause more balanced angiogenesis. We hypothesize that loss of HIFs promotes lung hypoplasia in BPD, and that stabilizing HIFs will promote more normal lung development in the premature neonate with evolving BPD. This proposal is for translational research to test the effect of new HIF-specific P4H inhibitors on lung in vitro and in vivo using the primate model of BPD. In vitro, P4H inhibition causes HIF-1alpha stability, VEGF expression, angiogenesis, and increased activity of kinases important in vascular growth. In lung explants, new HIF P4H inhibitors will be tested for their ability to stabilize HIFs and increase HIF-related proteins and kinase activities. In addition, HIF P4H inhibitor will be administered intravenously, intratracheally, and by both routes combined. Gas exchange, pulmonary mechanics and function, various clinical parameters, and HIF P4H inhibitor levels will be measured in vivo, and alveolar and vascular development, lung HIF proteins and HIF-related proteins and kinase activities, and tissue HIF P4H inhibitor levels will be quantitated ex vivo. Therapy at the level of HIF transcription factors to improve angiogenesis and alveolar development offers promise to prevent BPD.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project--Cooperative Agreements (U01)
Project #
5U01HL056263-12
Application #
7114953
Study Section
Special Emphasis Panel (ZHL1-CSR-P (S2))
Program Officer
Denholm, Elizabeth M
Project Start
1995-09-30
Project End
2009-08-31
Budget Start
2006-09-01
Budget End
2009-08-31
Support Year
12
Fiscal Year
2006
Total Cost
$238,068
Indirect Cost
Name
National Jewish Health
Department
Type
DUNS #
076443019
City
Denver
State
CO
Country
United States
Zip Code
80206
Vähätalo, Riika; Asikainen, Tiina M; Karikoski, Riitta et al. (2011) Expression of Transcription Factor GATA-6 in Alveolar Epithelial Cells Is Linked to Neonatal Lung Disease. Neonatology 99:231-40
Panayiotidis, Mihalis I; Stabler, Sally P; Allen, Robert H et al. (2009) Oxidative stress-induced regulation of the methionine metabolic pathway in human lung epithelial-like (A549) cells. Mutat Res 674:23-30
Ahmad, Aftab; Ahmad, Shama; Glover, Louise et al. (2009) Adenosine A2A receptor is a unique angiogenic target of HIF-2alpha in pulmonary endothelial cells. Proc Natl Acad Sci U S A 106:10684-9
Asikainen, Tiina M; White, Carl W (2007) HIF stabilizing agents: shotgun or scalpel? Am J Physiol Lung Cell Mol Physiol 293:L555-6
Asikainen, Tiina M; Waleh, Nahid S; Schneider, Barbara K et al. (2006) Enhancement of angiogenic effectors through hypoxia-inducible factor in preterm primate lung in vivo. Am J Physiol Lung Cell Mol Physiol 291:L588-95
White, Carl W (2006) Commentary on ""Hypoxia, hypoxic signaling, tissue damage, and detection of reactive oxygen species (ROS)"". Free Radic Biol Med 40:923-7
Asikainen, Tiina M; Chang, Ling-Yi; Coalson, Jacqueline J et al. (2006) Improved lung growth and function through hypoxia-inducible factor in primate chronic lung disease of prematurity. FASEB J 20:1698-700
Asikainen, Tiina M; White, Carl W (2005) Antioxidant defenses in the preterm lung: role for hypoxia-inducible factors in BPD? Toxicol Appl Pharmacol 203:177-88
Asikainen, Tiina M; Ahmad, Aftab; Schneider, Barbara K et al. (2005) Stimulation of HIF-1alpha, HIF-2alpha, and VEGF by prolyl 4-hydroxylase inhibition in human lung endothelial and epithelial cells. Free Radic Biol Med 38:1002-13
Asikainen, Tiina M; Ahmad, Aftab; Schneider, Barbara K et al. (2005) Effect of preterm birth on hypoxia-inducible factors and vascular endothelial growth factor in primate lungs. Pediatr Pulmonol 40:538-46

Showing the most recent 10 out of 11 publications