Growth of the pulmonary capillaries by angiogenesis is essential for alveolarization, and disruption of pulmonary angiogenesis contributes to the pathogenesis of bronchopulmonary dysplasia (BPD), the most common complication of premature birth. However, the molecular pathways that orchestrate pulmonary angiogenesis during development and disease are not fully understood. This gap in knowledge continues to confound efforts to develop targeted therapies to treat lung diseases caused by impaired angiogenesis, including BPD. Nuclear factor ?-B (NF?B) is a key regulator of inflammation, and growing evidence suggests that NF?B regulates angiogenesis in wound healing in cancer. In contrast, little is known about the role of NF?B in the developing lung. We recently demonstrated that NF?B is essential for alveolarization. NF?B is constitutively active in the neonatal, but quiescent in the adult lung, and inhibiting NF?B disrupts pulmonary angiogenesis and alveolarization in neonatal mice, but has no effect in adults. Blocking NF?B in neonatal primary pulmonary endothelial cells (PEC) impairs survival, proliferation, and in vitro angiogenesis. Activation of NF?B in the PEC corresponds to the period of angiogenesis in the developing lung, peaking at the onset of alveolarization, and decreasing to low levels by mid-alveolarization. However, the capacity for NF?B to be activated in the PEC is not intrinsic to the cell's maturation, as conditioned media obtained from early alveolar lung organ culture (EA-LCM), robustly activates NF?B and enhances migration in adult PEC. Global proteomic analysis to compare the early alveolar and adult lung secretomes identified factors secreted only by the early alveolar lung (EAL). Studies to examine the effect of neutralizing each of these proteins on the ability of the EA-LCM to promote NF?B activation and migration, allowed the identification of two putative activators of NF?B in the early alveolar lung: transforming growth factor-? induced protein (TGFBI) and alpha-fetoprotein (AFP). Both factors are expressed in the EAL in vivo but minimally expressed in the adult lung, and both are suppressed by injuries that disrupt alveolarization. Therefore, our data suggest the overall working hypothesis that factors uniquely secreted by the EAL promote lung angiogenesis and alveolarization by activating NF? B in the pulmonary endothelium by addressing two inter-related specific aims.
In Aim 1, we will examine if TGFBI and AFP secretion by the EAL induces a pro-angiogenic phenotype in the PEC via an NF?B-dependent pathway, and explore if TGFBI and AFP activate common or complementary patterns of gene expression.
Aim 2 will utilize in vivo gain and loss of function strategies to determine if disrupting TGFBI- or AFP-mediated activation of NF?B impairs alveolar growth during development and injury. The successful completion of these studies will establish a novel, physiologic role for NF?B in the developing lung, and identify new angiogenic factors that can be directly translated into therapeutic strategies to promote lung growth and regeneration in diseases marked by impaired pulmonary angiogenesis.

Public Health Relevance

The formation of the distal air sacs (alveolarization) requires the development of blood vessels by the process of angiogenesis. Disruption of angiogenesis and alveolarization in infants causes bronchopulmonary dysplasia, the most common complication of premature birth. Our studies will identify new proteins that direct angiogenesis in the developing lung, and explore new therapeutic strategies to promote lung growth by enhancing angiogenesis, an approach that may be applicable to diseases affecting both infants and adults.

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
Lin, Sara
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Stanford University
Schools of Medicine
United States
Zip Code
Alvira, Cristina M; Morty, Rory E (2017) Can We Understand the Pathobiology of Bronchopulmonary Dysplasia? J Pediatr 190:27-37
Vattulainen-Collanus, Sanna; Akinrinade, Oyediran; Li, Molong et al. (2016) Loss of PPAR? in endothelial cells leads to impaired angiogenesis. J Cell Sci 129:693-705
Alvira, Cristina M (2016) Aberrant Pulmonary Vascular Growth and Remodeling in Bronchopulmonary Dysplasia. Front Med (Lausanne) 3:21
Ehrhardt, Harald; Pritzke, Tina; Oak, Prajakta et al. (2016) Absence of TNF-? enhances inflammatory response in the newborn lung undergoing mechanical ventilation. Am J Physiol Lung Cell Mol Physiol 310:L909-18
Hou, Yanli; Liu, Min; Husted, Cristiana et al. (2015) Activation of the nuclear factor-?B pathway during postnatal lung inflammation preserves alveolarization by suppressing macrophage inflammatory protein-2. Am J Physiol Lung Cell Mol Physiol 309:L593-604
Kim, Francis Y; Barnes, Elizabeth A; Ying, Lihua et al. (2015) Pulmonary artery smooth muscle cell endothelin-1 expression modulates the pulmonary vascular response to chronic hypoxia. Am J Physiol Lung Cell Mol Physiol 308:L368-77
Alvira, Cristina M (2014) Nuclear factor-kappa-B signaling in lung development and disease: one pathway, numerous functions. Birth Defects Res A Clin Mol Teratol 100:202-16
Hilgendorff, Anne; Reiss, Irwin; Ehrhardt, Harald et al. (2014) Chronic lung disease in the preterm infant. Lessons learned from animal models. Am J Respir Cell Mol Biol 50:233-45
Baker, Christopher D; Alvira, Cristina M (2014) Disrupted lung development and bronchopulmonary dysplasia: opportunities for lung repair and regeneration. Curr Opin Pediatr 26:306-14