Modulation of Recovery from Neonatal Hyperoxic Lung Injury by Sex as a Biological Variable
Recovery from lung injury during the neonatal period requires the orchestration of many biological pathways. Modulation of biological pathways can drive the developing lung towards proper repair or persistent maldevelopment after injury that can lead to a disease phenotype. Sex as a biological variable can modulate these pathways differently in the male and female lung exposed to neonatal hyperoxia. In this study, we assessed the contribution of cellular diversity in the male and female neonatal lung following injury. Our objective was to investigate sex and cell-type specific transcriptional changes that drive repair or persistent injury in the neonatal lung at single-cell resolution and delineate the alterations in the immune-endothelial cell communication networks in the developing lung using single cell RNA sequencing (sc-RNAseq) in a murine model of hyperoxic lung injury. We generated transcriptional profiles of >55,000 cells isolated from the lungs of postnatal day 1 (PND 1) andpostnatal day 21 (PND 21) neonatal male and female C57BL/6 mice exposed to 95% FiO2between PND 1-5 (saccular stage of lung development).We show the presence of sex-based differences in the transcriptional states of lung endothelial and immune cells at PND 1 and PND 21. Furthermore, we demonstrate that biological sex significantly influences the response to injury, with a greater number of differentially expressed genes showing sex-specific patterns than those shared between male and female lungs. Pseudotime trajectory analysis highlighted genes needed for lung development that were altered by hyperoxia. Finally, we show intercellular communication between endothelial and immune cells at saccular and alveolar stages of lung development with sex-based biases in the cross-talk and identify novel ligand-receptor pairs. Our findings provide valuable insights into the cell diversity, transcriptional state, developmental trajectory, and cell-cell communication underlying neonatal lung injury, with implications for understanding lung development and therapeutic interventions while highlighting the crucial role of sex as a biological variable. Overall design: C57BL/6N neonatal mice were exposed to room air (21% O2) or hyperoxia (95% FiO2) from PND 1-5 and then moved to room air. Mice were euthanized at PND 1 or PND 21. Single cell suspension was prepared for each of the four groups: male room air, female room air at PND 1 and male room air, female room air, male hyperoxia and female hyperoxia at the PND 21. Each sample was comprised of pooled lung tissue from three mice.