The role of sex chromosomes in neonatal hyperoxic lung injury

Bronchopulmonary dysplasia (BPD) is the most common complication affecting preterm neonates and is defined by supplemental oxygen dependence at 36 weeks postmenstrual age. Advances in neonatal care have improved overall survival of preterm neonates though BPD prevalence continues to increase. BPD develops after early-life lung injury caused by myriad pre- and postnatal factors such as the administration of supplemental oxygen. Though a lifesaving therapeutic intervention, high concentrations of oxygen (hyperoxia) arrest alveolarization and vascularization and induce inflammation. Neonates with BPD face challenges in lung function that can persist throughout adulthood. BPD has a striking male bias for both incidence and severity, demonstrating the need to interrogate sex as a biological variable in lung development, injury, and repair processes. Previous work from our lab showed that female chromosome complement (XX) is protective against lung injury, independent of gonadal sex (ovaries and testes). It is unknown if the protective effect is due to the presence of two X chromosomes or the absence of a Y chromosome. The goal of this proposal is to interrogate dosage sensitivity of sex chromosomes and an X-linked gene, Kdm6a, in an early-life hyperoxia mouse model of BPD. I hypothesize X chromosome mechanisms and dosage contribute to female resilience against hyperoxic lung injury. This hypothesis will be tested by the following: Aim 1) Determine the role of sex chromosome dosage in neonatal hyperoxic lung injury and Aim 2) Determine the role of endothelial Kdm6a in neonatal hyperoxic lung injury. In Aim 1, I will assess lung morphometry and vascularization in room air and hyperoxia-exposed in the XY star (XY*) mouse model that has XX, XO, XY, and XXY genotypes. My preliminary data shows modulation of alveolarization after injury as a function of chromosome dosage. I will then determine cell-type specific gene signatures after hyperoxia exposure using single-cell RNA sequencing. In Aim 2, I will determine the role of endothelial Kdm6a in female neonatal mouse pups during development and after hyperoxic lung injury. X chromosome inactivation (XCI) is a dosage compensation mechanism whereby supernumerary X chromosomes are transcriptionally silenced so genes from only one X chromosome are expressed. However, some genes escape XCI. Intriguingly, preliminary data from our lab show a female- specific induction of an XCI escapee, Kdm6a, after exposure to hyperoxia. I will test the hypothesis that endothelial knockdown of Kdm6a intensifies hyperoxic lung injury in female mice. To determine the role of Kdm6a in epigenetic regulation and alterations to the chromatin landscape, I will perform bulk RNA-seq, ATAC- seq, and CUT&RUN. Completion of this proposal will advance mechanistic knowledge of sex-specific responses to respiratory insults and potentially inform the development of precision medicine approaches. Project Number: 1F31HL179994-01 | Fiscal Year: 2025 | NIH Institute/Center: National Heart Lung and Blood Institute (NHLBI) | Principal Investigator: Rose Albert | Institution: UNIVERSITY OF PENNSYLVANIA, PHILADELPHIA, PA | Award Amount: $49,538 | Activity Code: F31 | Study Section: Special Emphasis Panel[ZRG1 F10A-R (20)] View on NIH RePORTER: https://reporter.nih.gov/project-details/1F31HL17999401