C107-22 Upregulating Mitophagy Inhibits Lung Injury of Bronchopulmonary Dysplasia by Repressing Cytoplasmic MtDNA Release

Abstract Background Premature infants are at high risk of developing bronchopulmonary dysplasia (BPD), a chronic lung disease with limited therapeutic options. Although mitochondrial injury has been documented in BPD and its experimental models, whether impaired mitophagy contributes to the accumulation of damaged mitochondria and subsequent lung injury remains unknown. We hypothesized that insufficient mitophagy leads to the release of mitochondrial DNA (mtDNA) from damaged mitochondria, which triggers lung injury in BPD. Methods The scRNA-seq datasets (GSE275938) from term infants (7-20 days old) and BPD (born at 25-27 weeks of gestation and analyzed at 7 months of age) were reanalyzed to assess cell type-specific alterations in mitophagy pathway enrichment. MitoQC mitophagy reporter and C57BL/6J mice (12 h old) were exposed to hyperoxia (95% O2) for 3 days followed by recovery in room air until postnatal day (pnd) 14. Primary human fetal lung endothelial cells (ECs) were exposed to hyperoxia (95% O2/5% CO2) for 24 h followed by 24 h recovery in air. Mitophagy activators (SPB08007 and urolithin A at 1 and 5 mg/kg, i.p.) were administered from pnd4 to pnd13. EndoNP1 nanoparticles carrying the parkin gene under the control of the human CDH5 promoter were delivered via retro-orbital injection to enhance endothelial mitophagy. Results scRNA-seq analysis revealed that the mitophagy pathway was abundant in epithelial, endothelial, mesenchymal, and immune cells, but its enrichment was reduced in infants with BPD compared with term infants. Specifically, endothelial cells from infants with BPD exhibited decreased mitophagy along with enrichment of the cGAS-STING, TLR9, and inflammasome pathways. Consistently, mitophagy was decreased in the lung of mice exposed to hyperoxia as neonates and in primary human fetal lung ECs. Treatment with SPB08007 or urolithin A enhanced mitophagy and mitigated hyperoxia-induced alveolar and vascular simplification in mice. Furthermore, nanoparticle-mediated endothelial parkin overexpression increased mitophagy and inhibited hyperoxic lung injury. These beneficial effects were associated with reduced cytosolic mtDNA release. Conclusion Lung mitophagy is impaired in infants with BPD and a mouse model of neonatal hyperoxia. This leads to cytosolic mtDNA release and activation of innate immune pathways. Enhancing mitophagy represents a promising therapeutic strategy to prevent hyperoxic lung injury in BPD. This abstract is funded by: R01HL166327