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% FiO2, 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.

Role of Growth Differentiation Factor 15 in Lung Disease and Senescence: Potential Role Across the Lifespan

Growth Differentiation Factor 15 (GDF15) is a divergent member of transforming growth factor-beta (TGF-β) superfamily and is ubiquitously expressed, under normal physiological conditions. GDF15 expression increases during many pathological states and serves a marker of cellular stress. GDF15 has multiple and even paradoxical roles within a pathological condition, as its effects can be dose- and time-dependent and vary based on the targeted tissues and downstream pathways. GDF15 has emerged as one of the most recognized proteins as part of the senescence associated secretory phenotype. Cellular senescence plays a major role in many lung diseases across the life-span from bronchopulmonary dysplasia in the premature neonate to COPD and idiopathic pulmonary fibrosis in aged adults. GDF15 levels have been reported to be as a useful biomarker in chronic obstructive pulmonary disease, lung fibrosis and pulmonary arterial hypertension and predict disease severity, decline in lung function and mortality. Glial-cell-line-derived neurotrophic factor family receptor alpha-like (GFRAL) in the brain stem has been identified as the only validated GDF15 receptor and mediates GDF15-mediated anorexia and wasting. The mechanisms and pathways by which GDF15 exerts its pulmonary effects are being elucidated. GDF15 may also have an impact on the lung based on the changes in circulating levels or through the central action of GDF15 activating peripheral metabolic changes. This review focuses on the role of GDF15 in different lung diseases across the lifespan and its role in cellular senescence.