232 - Apelinergic Signaling: A New Target for Pulmonary Hypertension Associated with Bronchopulmonary Dysplasia

Poster Number: 232
Publication Number: 232.222

Alice N. Hackett, Vanderbilt University School of Medicine, NASHVILLE, TN, United States; Nicholas M. Negretti, Vanderbilt University Medical Center, Nashville, TN, United States; Erin Plosa, Vanderbilt University Medical Center, Nashville, TN, United States; John Benjamin, Vanderbilt University Medical Center, Nashville, TN, United States; Christopher S. Jetter, Monroe Carell Jr. Children's Hospital at Vanderbilt, Murfreesboro, TN, United States; Jonathan A. Kropski, Vanderbilt University Medical Center, Nashville, TN, United States; Jennifer Sucre, Vanderbilt University School of Medicine, Nashville, TN, United States

Background: Bronchopulmonary dysplasia (BPD) is a leading morbidity in survivors of preterm birth; severe BPD is associated with vascular changes and pulmonary hypertension (PH). Molecular drivers of BPD and PH pathogenesis are not defined, and there is no cure. Apelin is a peptide synthesized in heart and lung endothelium implicated as protective in adult PH models. Apelin’s role in lung vascular development and neonatal injury response remains uncharacterized.

Objective: Our goal is to define apelin expression trajectory in normal lung development and characterize the effect of saccular-stage injury on the apelin pathway.

Design/Methods: We have established a mouse BPD model combining hyperoxia (70% oxygen on postnatal day (P)1-5) and inflammation (intratracheal lipopolysaccharide (LPS) on P3 and 4). To characterize the injury phenotype, we performed echocardiography and measured vascular medial wall thickness by histology. To define the trajectory of apelin expression during development and injury, we performed single-cell RNA sequencing (scRNAseq) at 9 time points from embryonic day (E)12 to postnatal (P)day 14 and 4 timepoints during injury and recovery (P3-P14). Apelin expression was spatially and temporally localized using RNA in situ hybridization (ISH). For validation, we examined human lung tissue from preterm infants with and without mechanical ventilation.

Results: Echocardiography in injured mice aged to 2 months demonstrates decreased pulmonary artery acceleration time and increased right ventricular wall thickness relative to controls. Medial wall thickness of pulmonary vasculature in injured mice at P14 (p < 0.0001) and P28 (p < 0.01) is increased. By scRNAseq, apelin and its receptor are expressed by distinct endothelial subpopulations, with apelin restricted to a subset of capillary endothelial cells. During normal development, apelin expression increases before birth at E18 and is consistent across postnatal lung development. In neonatal injury, scRNAseq and RNA ISH shows decreased apelin expression relative to controls at P5 (p < 0.001), which persists at P14 (p < 0.01) and P28 (p < 0.01). Saccular stage human lungs had decreased apelin expression after mechanical ventilation when compared with infants never ventilated (p < 0.001).Conclusion(s): Our injury model of neonatal injury results in vascular changes consistent with pulmonary hypertension. Apelinergic signaling emerges in the saccular stage of lung development. With neonatal injury and recovery, apelin expression decreases. Future work targeting the apelin pathway may identify novel therapies for BPD and PH.