Endothelial Adenosine Monophosphate-Activated Protein Kinase-Alpha1 Deficiency Potentiates Hyperoxia-Induced Experimental Bronchopulmonary Dysplasia and Pulmonary Hypertension

Abstract

Bronchopulmonary dysplasia and pulmonary hypertension, or BPD-PH, are serious chronic lung disorders of prematurity, without curative therapies. Hyperoxia, a known causative factor of BPD-PH, activates adenosine monophosphate-activated protein kinase (AMPK) α1 in neonatal murine lungs; however, whether this phenomenon potentiates or mitigates lung injury is unclear. Thus, we hypothesized that (1) endothelial <i>AMPKα1</i> is necessary to protect neonatal mice against hyperoxia-induced BPD-PH, and (2) <i>AMPKα1</i> knockdown decreases angiogenesis in hyperoxia-exposed neonatal human pulmonary microvascular endothelial cells (HPMECs). We performed lung morphometric and echocardiographic studies on postnatal day (P) 28 on endothelial <i>AMPKα1</i>-sufficient and -deficient mice exposed to 21% O₂ (normoxia) or 70% O₂ (hyperoxia) from P1-P14. We also performed tubule formation assays on control- or <i>AMPKα1</i>-siRNA transfected HPMECs, exposed to 21% O₂ or 70% O₂ for 48 h. Hyperoxia-mediated alveolar and pulmonary vascular simplification, pulmonary vascular remodeling, and PH were significantly amplified in endothelial <i>AMPKα1</i>-deficient mice. <i>AMPKα1</i> siRNA knocked down <i>AMPKα1</i> expression in HPMECs, and decreased their ability to form tubules in normoxia and hyperoxia. Furthermore, <i>AMPKα1</i> knockdown decreased proliferating cell nuclear antigen expression in hyperoxic conditions. Our results indicate that <i>AMPKα1</i> is required to reduce hyperoxia-induced BPD-PH burden in neonatal mice, and promotes angiogenesis in HPMECs to limit lung injury.