Loss of microRNA-30a and sex-specific effects on the neonatal hyperoxic lung injury

Background Bronchopulmonary dysplasia (BPD) is characterized by an arrest in lung development and is a leading cause of morbidity in premature neonates. It has been well documented that BPD disproportionally affects males compared to females, but the molecular mechanisms behind this sex-dependent bias remain unclear. Female mice show greater preservation of alveolarization and angiogenesis when exposed to hyperoxia, accompanied by increased miR-30a expression. In this investigation, we tested the hypothesis that loss of miR-30a would result in male and female mice experiencing similar impairments in alveolarization and angiogenesis under hyperoxic conditions. Methods Wild-type and miR-30a −/− neonatal mice were exposed to hyperoxia [95% FiO 2 , postnatal day [PND1-5] or room air before being euthanized on PND21. Alveolarization, pulmonary microvascular development, differences in lung transcriptome, and miR-30a expression were assessed in lungs from WT and miR-30a −/− mice of either sex. Blood transcriptomic signatures from preterm newborns (with and without BPD) were correlated with WT and miR-30a −/− male and female lung transcriptome data. Results Significantly, the sex-specific differences observed in WT mice were abrogated in the miR-30a −/− mice upon exposure to hyperoxia. The loss of miR-30a expression eliminated the protective effect in females, suggesting that miR-30a plays an essential role in regulating alveolarization and angiogenesis. Transcriptome analysis by whole lung RNA-Seq revealed a significant response in the miR-30a −/− female hyperoxia-exposed lung, with enrichment of pathways related to cell cycle and neuroactive ligand–receptor interaction. Gene expression signature in the miR-30a −/− female lung associated with human BPD blood transcriptomes. Finally, we showed the spatial localization of miR-30a transcripts in the bronchiolar epithelium. Conclusions miR-30a could be one of the biological factors mediating the resilience of the female preterm lung to neonatal hyperoxic lung injury. A better understanding of the effects of miR-30a on pulmonary angiogenesis and alveolarization may lead to novel therapeutics for treating BPD.