The role of SEX chromosomes in neonatal hyperoxic lung injury

The National Heart, Lung, and Blood Institute awarded The Trustees of The University of Pennsylvania $248,266 on January 17, 2026, under the Cardiovascular Diseases Research program (CFDA 93.837) to investigate the role of sex chromosomes in neonatal hyperoxic lung injury as a mechanism of bronchopulmonary dysplasia.

The recipient will interrogate dosage sensitivity of sex chromosomes and the X-linked gene KDM6A in an early-life hyperoxia mouse model of bronchopulmonary dysplasia. The research comprises two aims: determining the role of sex chromosome dosage in neonatal hyperoxic lung injury through lung morphometry and vascularization assessment in the XY STAR mouse model carrying XX, XO, XY, and XXY genotypes; and determining the role of endothelial KDM6A in neonatal hyperoxic lung injury. Preliminary data indicates modulation of alveolarization after injury as a function of chromosome dosage. The work addresses the striking male bias in bronchopulmonary dysplasia incidence and severity by testing whether X chromosome mechanisms and dosage contribute to female resilience against hyperoxic lung injury.

Performance occurs in Philadelphia, Pennsylvania, with a period of performance through May 31, 2028. The funding is classified as a Project Grant, an assistance type supporting discrete, circumscribed research projects.

Abstract

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.