167 - Mitochondrial damage causes hyperoxia-induced endothelial cell dysfunction and lung injury in neonatal mice
Monday, May 1, 2023
9:30 AM – 11:30 AM ET
Poster Number: 167 Publication Number: 167.438
Zihang Feng, Brown University, Dallas, TX, United States; Katy B. Hegarty, Brown University, Providence, RI, United States; Jared Hunter, Brown University, Cohoes, NY, United States; Phyllis A.. Dennery, The Warren Alpert Medical School of Brown University/Hasbro Children's Hospital, Providence, RI, United States; Hongwei Yao, Brown University, Providence, RI, United States
Associate Professor (Research) Brown University Providence, Rhode Island, United States
Background: Ventilatory support, such as supplemental oxygen used to save these premature infants, may cause bronchopulmonary dysplasia (BPD). This is characterized by vascular and alveolar simplification in the lung. Although human umbilical vein endothelial cells (ECs) from BPD-susceptible infants have increased mitochondrial DNA damage and reduced oxidative phosphorylation (Oxphos), whether damaged mitochondria contribute to lung EC dysfunction and vascular simplification in BPD is unclear. Objective: We hypothesized that hyperoxia damages lung endothelial mitochondria, resulting in impaired EC function and lung injury. Design/Methods: We exposed primary human fetal lung ECs, a mouse fetal lung EC line, and newborn mice to hyperoxia, and determined mitochondrial biogenesis, mitochondrial reactive oxygen species (mitROS), mitochondrial membrane potential (ΔΨm), Oxphos and mitochondrial morphology. We treated hyperoxia-exposed cells and neonatal mice with a newly developed mitophagy activator SPB08007 (without triggering loss of ΔΨm), and evaluated migration and tube formation in vitro, as well as mean linear intercept, radial alveolar count, and vessel numbers in the lung. Results: Hyperoxia (95% O2/5% CO2) reduced mitochondrial biogenesis, ΔΨm, and Oxphos, but increased mitROS in cultured lung ECs. Morphologically, hyperoxia caused mitochondrial fusion as indicated by mitochondrial elongation and increased Mfn1 and Mfn2 levels. Knockdown of Mfn1 further increased mitROS, and reduced ΔΨm and Oxphos in these cells exposed to hyperoxia. Western blot and electronic microscopy revealed that hyperoxia caused mitophagy in vitro, as reflected by increased LC3BII, SQSTM1/p62, Lamp1, Pink1 and Parkin expression as well as the remnant of cristae structure inside autolysosome. Likewise, lung LC3BII expression and co-localization of LC3B and Vdac1 in the endothelium were increased in mice exposed to hyperoxia ( >95% O2) as neonates. Knockdown of Parkin using siRNA further increased mitROS but decreased Oxphos and impaired tube formation in hyperoxia-exposed lung ECs Conversely, treatment with SPB08007 reduced mitROS and increased Oxphos in hyperoxia-exposed ECs. Additionally, SPB08007 inhibited hyperoxia-induced impairment of migration and angiogenesis in vitro, as well as vascular and alveolar simplification in the lung.
Conclusion(s): Hyperoxia damages mitochondria, whereas activating mitophagy attenuates hyperoxia-induced EC dysfunction and lung injury. This has implications in preventing lung injury in BPD by activating mitophagy.
